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+The Project Gutenberg EBook of A Distributional Study of the Amphibians of
+the Isthmus of Tehuantepec, Mexico, by William E. Duellman
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, Mexico
+
+Author: William E. Duellman
+
+Release Date: December 30, 2011 [EBook #38440]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK A DISTRIBUTIONAL STUDY OF ***
+
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+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
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+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+
+August 16, 1960
+
+A Distributional Study of the Amphibians
+of the Isthmus of Tehuantepec, México
+
+BY
+WILLIAM E. DUELLMAN
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1960
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+
+August 16, 1960
+
+A Distributional Study of the Amphibians
+of the Isthmus of Tehuantepec, México
+
+BY
+WILLIAM E. DUELLMAN
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1960
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
+Robert W. Wilson
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+Published August 16, 1960
+
+UNIVERSITY OF KANSAS
+Lawrence, Kansas
+
+PRINTED IN
+THE STATE PRINTING PLANT
+TOPEKA, KANSAS
+1960
+
+28-3859
+
+
+
+
+A Distributional Study of the Amphibians of the Isthmus of Tehuantepec,
+México
+
+BY
+
+WILLIAM E. DUELLMAN
+
+
+
+
+CONTENTS
+
+
+                                                               PAGE
+INTRODUCTION                                                     21
+  Acknowledgments                                                23
+  Field Studies in the Isthmus of Tehuantepec                    23
+  Sources of Material                                            24
+
+DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC                        25
+  Physiography                                                   25
+  Climate                                                        28
+  Vegetation                                                     29
+  The Sierra de los Tuxtlas                                      32
+
+GAZETTEER                                                        33
+
+THE AMPHIBIAN FAUNA OF THE LOWLANDS                              37
+  Composition of the Fauna                                       37
+  Ecology of the Fauna                                           38
+  Distribution of the Fauna                                      42
+
+THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS      44
+
+ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION                45
+
+ACCOUNTS OF SPECIES                                              49
+
+SUMMARY                                                          68
+
+LITERATURE CITED                                                 69
+
+
+
+
+INTRODUCTION
+
+
+Few regions in Middle America are so important zoogeographically as is
+the Isthmus of Tehuantepec, that neck of land connecting North America
+with Central America, separating the Pacific Ocean from the Gulf of
+Mexico by a distance of only about 220 kilometers (airline), and
+forming a low break between the highlands of México and those of
+Central America. Before World War II the isthmus could be reached
+readily only by railroad or by ocean vessel to Salina Cruz or
+Coatzacoalcos. With the advent of roads, principally the Trans-isthmian
+Highway, vast areas of the interior of the isthmus became accessible to
+biologists. Nevertheless, long before roads were built in the isthmian
+region collectors and biologists visited it, especially the town of
+Tehuantepec, from which collections date back to the 1870's. Therefore,
+it is rather surprising that no attempt has been made to present a
+faunal list of the amphibians or reptiles of the isthmus. Ruthven
+(1912) summarized his collections from the vicinity of Cuatotolapam,
+Veracruz, and Hartweg and Oliver (1940) presented an annotated list of
+the species collected by them in the vicinity of Tehuantepec. In recent
+years there have been only a few papers reporting species from the
+isthmus (Fugler and Webb, 1957; Langebartel and Smith, 1959). The
+zoogeographic significance of the Isthmus of Tehuantepec is exemplified
+by the works of Burt (1931), Duellman (1958), Gloyd (1940), Oliver
+(1948), and Stuart (1941), who in their discussions of evolution and
+dispersal of various genera of reptiles, pointed out that the Isthmus
+of Tehuantepec was a region of zoogeographic importance.
+
+Originally I intended to study the entire herpetofauna of the isthmus.
+But I have not had opportunity to study all of the reptiles, and I have
+not had the inclination to solve certain taxonomic problems concerning
+them. The amphibians that I collected, together with all other known
+specimens in museums, have been studied. Therefore, the present report
+is concerned only with the amphibians. Only the amphibians of the
+lowlands of the isthmus have been sampled adequately. Although I have
+commented on the highland species in the discussion of distribution,
+they are not included in the systematic section, which deals solely
+with the 36 species definitely known to occur in the lowlands of the
+isthmus.
+
+Among the species of amphibians that I would expect to occur in the
+isthmus, the only one not yet found there is _Hyla phaeota_. Sufficient
+specimens of most of the species are available to show their variation
+in the isthmus. Consequently, the systematics of these amphibians is on
+a fairly substantial basis. Probably certain species in the isthmian
+region will be found to be conspecific with others to the south, for
+example _Hyla ebraccata_ with _Hyla leucophyllata_ and _Hyla
+robertmertensi_ with _Hyla underwoodi_. Nevertheless, such taxonomic
+changes will not affect the distributional picture presented here. Our
+greatest lack of knowledge concerning the amphibians is about their
+life histories, as may be illustrated by the following questions, all
+of which now are without definite answers. Where do many of the small
+frogs conceal themselves during the dry season? What amount of, if any,
+interspecific competition exists among several species of tree frogs,
+all of which breed in the same ponds? What factors in the environment
+permit certain amphibians, but not others, to live in the humid
+rainforests, as well as in the arid tropical scrub forest? The answers
+to these questions and many others must await additional field studies.
+
+The purpose of this paper is to make known the species of amphibians
+living in the Isthmus of Tehuantepec, to describe the environments in
+which they live, and to discuss their distribution in the isthmus. With
+respect to the distribution of animals in the Isthmus of Tehuantepec I
+will attempt to explain the present patterns of distribution with
+special reference to climatic fluctuation in the Pleistocene.
+
+
+_Acknowledgments_
+
+My extensive field work in the Isthmus of Tehuantepec was made possible
+by grants from the Penrose Fund of the American Philosophical Society
+(1956) and the Bache Fund of the National Academy of Sciences (1958).
+Furthermore, my field work received the hearty support of the Museum of
+Zoology at the University of Michigan; for their cooperation I am
+indebted to Norman Hartweg, T. H. Hubbell, and Henry van der Schalie.
+In the course of my studies I received helpful suggestions from Norman
+Hartweg, L. C. Stuart, and Charles F. Walker, to whom I am grateful.
+For permission to examine specimens in their care I thank Doris M.
+Cochran, Hobart M. Smith, and Richard G. Zweifel. I am deeply indebted
+to Thomas MacDougall for many suggestions and for aid in preparing the
+gazetteer. I am most grateful for the efforts of my field companions,
+Richard E. Etheridge, Jerome B. Tulecke, John Wellman, and especially
+my wife, Ann S. Duellman, who spent many long days and nights gathering
+much of the data on which this report is based. Our work in the isthmus
+was furthered by the generous help and hospitality of many residents,
+especially the late Wilbur Barker of Tehuantepec, Fortunado Delgado of
+Rancho Las Hojitas near Acayucan, César Fárjas of Donají, and Juan
+Mayol of San Andrés Tuxtla. Profesor Jordi Juliá Z. of the Laboratorio
+de Entomología, Comisión del Papaloapan, Ciudad Alemán, Veracruz,
+helped make possible my field work in 1959; for this he has my sincere
+thanks. In conclusion I express my gratitude to Ing. Juan Lozano
+Franco, Secretaria de Agricultura y Ganadería, for providing me with
+the necessary permits.
+
+
+_Field Studies in the Isthmus of Tehuantepec_
+
+I first visited the Isthmus of Tehuantepec and collected on the Pacific
+lowlands of the isthmus in July, 1955. At that time heavy rains and
+impassable roads restricted travelling. In February and March of 1956
+my wife and I concentrated our efforts in the central region between
+the Río Jaltepec and Matías Romero, but also made several trips across
+the isthmus to gather ecological data in the dry season. In July of the
+same year, accompanied by Richard E. Etheridge, we again crossed the
+isthmus several times in order to gather ecological data in the wet
+season, and studied especially hylid frogs, most of which had not been
+seen in the dry season. Accompanied by Jerome B. Tulecke and John
+Wellman, I collected again in the isthmus in July, 1958, between Salina
+Cruz and Tehuantepec, and between Coatzacoalcos and Cosoleacaque. In
+March and April, 1959, I collected at Ciudad Alemán. Nearly 1200
+specimens of 30 species of amphibians were thus collected in the
+Isthmus of Tehuantepec; all specimens are now in the Museum of Zoology
+at the University of Michigan. Of other species known from the isthmus,
+I have had field experience with all but one (_Bolitoglossa
+veracrucis_) in other parts of México.
+
+
+_Sources of Material_
+
+There are in museum collections nearly 3000 specimens of amphibians
+with reliable data from the Isthmus of Tehuantepec. Among the first
+herpetological specimens collected in the isthmian region are those
+assembled by Francis Sumichrast in the 1870's from the vicinity of
+Santa Efigenia and Tapanatepec, Oaxaca. These specimens were sent to
+the United States National Museum and the Museum National d'Histoire
+Naturelle in Paris; many served as the types of new species: _Bufo
+canaliferus_ Cope, _Eleutherodactylus rugulosus_ Cope, _Syrrhophus
+leprus_ Cope, and _Hylella sumichrasti_ Brocchi. In 1911 Alexander G.
+Ruthven collected in the savanna country near Cuatotolapam, Veracruz;
+the report on his collections (1912) is the first dealing with the
+herpetofauna of a part of the isthmus. His specimens are in the
+collection of the University of Michigan Museum of Zoology. Norman
+Hartweg and James A. Oliver collected for the University of Michigan
+Museum of Zoology in the vicinity of Tehuantepec, Oaxaca, during the
+summer of 1936. The results of their work were published as an
+annotated list of species occurring on the Pacific slopes of the
+isthmus (1940). Hobart M. Smith collected in the vicinity of
+Tehuantepec in January, 1940; his specimens are in the United States
+National Museum. Specimens collected by Smith served as the types of
+_Eleutherodactylus avocalis_ Taylor and Smith and _Diaglena reticulata_
+Taylor. Walter W. Dalquest collected vertebrates for the University of
+Kansas in southern Veracruz in the winters of 1947 and 1948; he spent
+about six months on the Gulf lowlands of the isthmus, principally in
+the vicinity of Jesús Carranza. For the past two decades Thomas
+MacDougall, a resident of New York City, has spent his winters
+collecting biological specimens in southern México. He makes his
+headquarters at Tehuantepec, but his compulsion to see the "back
+country" has taken him to many remote parts of southern Oaxaca. His
+earlier collections are in the American Museum of Natural History; the
+later ones are in the University of Illinois Museum of Natural History.
+
+Minor collections include those made by Matthew W. Stirling at San
+Lorenzo, Veracruz, February-April, 1946 (United States National
+Museum), by Fred G. Thompson on a trip across the isthmus in December,
+1955 (University of Michigan Museum of Zoology), by the University of
+Kansas Museum of Natural History field party under the direction of
+Rollin H. Baker at Tolosita, Oaxaca, and by David A. Langebartel and
+associates from southern Oaxaca in June, 1958 (University of Illinois
+Museum of Natural History).
+
+In the collections of the United States National Museum are several
+species of amphibians sent to the museum from Tehuantepec by Francis
+Sumichrast. These include _Bolitoglossa platydactyla_ (USNM 30305,
+30344-6, 30528), _Bolitoglossa rufescens_ (10042), _Chiropterotriton
+chiropterus_ (30347), _Lineatriton lineola_ (30353), _Parvimolge
+townsendi_ (30352), _Pseudoeurycea cephalica_ (30350), _Thorius
+pennatulus_ (30348-9), _Hyla miotympanum_ (30302-3), and _Hyla picta_
+(30304). Because of the poor condition of the specimens, determinations
+of those listed as _Bolitoglossa rufescens_ and _Pseudoeurycea
+cephalica_ are uncertain. With the exception of the _Bolitoglossa
+rufescens_, which is stated to have come from Santa Efigenia, all of
+these specimens are catalogued as having come from Tehuantepec. None of
+these species has since been recorded from the Pacific slopes of the
+isthmus; however, they all occur in the vicinity of Orizaba, Veracruz.
+Probably Sumichrast carried the specimens with him from Orizaba, his
+home before moving to Santa Efigenia, and shipped them from Tehuantepec
+to the United States National Museum. These species definitely should
+not be considered as inhabitants of the Pacific slopes of the Isthmus
+of Tehuantepec.
+
+
+
+
+DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC
+
+
+The Isthmus of Tehuantepec is a strip of land forming a low pass, which
+separates the mountain masses of México proper from those of Central
+America, and at the same time provides a continuum of lowlands from the
+Gulf of Mexico to the Pacific Ocean. This topography combines with the
+climatic conditions to create extremely diverse environments, the
+distribution of which can be adequately understood only after an
+acquaintance with the topography and climate of the region.
+
+
+_Physiography_
+
+In east-central Oaxaca the mountain masses comprising the Sierra Madre
+Oriental and the Sierra del Sur terminate in a series of ranges--Sierra
+de Juárez, Sierra de los Míjes, and Sierra de Choapam. From lofty
+peaks, such as Cerro de Zempoaltepetl (3400 meters), the highlands
+diminish eastward to succeedingly lower ridges, until in the middle of
+the Isthmus of Tehuantepec the continental divide is about 250 meters
+above sea level. Eastward from this low divide the land rises to form
+the Sierra Madre de Chiapas, which is continuous with the highland
+masses of Guatemala.
+
+For the purposes of this description, the lowlands of the isthmus may
+be divided into three parts--the Gulf Coastal Plain, the central
+ridges, and the Pacific Coastal Plain, which in the isthmus is called
+the Plains of Tehuantepec (Figs. 1 and 2).
+
+The Gulf Coastal Plain is broad and fairly level near the coast, but
+rolling in the interior. The plain, throughout most of its length in
+the isthmus, is at least 75 kilometers wide. The majority of the region
+in the isthmus is drained by the Río Coatzacoalcos, which flows in a
+northerly course to the Gulf of Mexico. The western part is drained by
+the Río San Juan, the principal tributary of the Río Papaloapan. Behind
+the coastal dunes are frequent, and sometimes large, lagoons.
+Immediately inland from Coatzacoalcos and along the lower stretches of
+the Río Papaloapan are extensive marshes. Essentially the entire
+coastal plain, with the exception of the coastal dunes, consists of
+rich alluvial deposits.
+
+[Illustration: FIG. 1. Map of the Isthmus of Tehuantepec based on the
+American Geographical Society's "Map of Hispanic America on the Scale
+of 1:1,000,000."
+
+The localities shown are numbered in the gazetteer; the numerical
+sequence of localities is an arrangement whereby north takes precedence
+over south and west over east. 1. Alvarado. 2. Lerdo de Tejada. 3.
+Tlacotalpan. 4. Tula. 5. Tecolapan. 6. Amatitlán. 7. Cosamaloapan. 8.
+Chacaltianguis. 9. Novillero. 10. Ciudad Alemán. 11. Papaloapan. 12.
+Tuxtepec. 13. Cuatotolapam. 14. Hueyapan. 15. Berta. 16. Coatzacoalcos.
+17. Ayentes. 18. Río de las Playas. 19. Cosoleacaque. 20. Minatitlán.
+21. Acayucan. 22. Aquilera. 23. San Lorenzo. 24. Naranja. 25. Suchil.
+26. Jesús Carranza. 27. La Oaxaqueña. 28. Ubero. 29. Donají. 30.
+Tolosita. 31. El Modelo. 32. Sarabia, 33. Guichicovi. 34. La Princesa.
+35. Santa María Chimalapa. 36. Matías Romero. 37. Santo Domingo Petapa.
+38. El Barrio. 39. Palmar. 40. Chivela. 41. Santiago Chivela. 42.
+Nizanda. 43. Agua Caliente. 44. Portillo Los Nanches. 45. Ixtepec. 46.
+La Ventosa. 47. Zanatepec. 48. Unión Hidalgo. 49. Tres Cruces. 50.
+Juchitán. 51. Escurano. 52. Salazar. 53. Santa Efigenia. 54.
+Tequisistlán. 55. Cerro de Quiengola. 56. San Pablo. 57. Mixtequilla.
+58. Tapanatepec. 59. Zarzamora. 60. Limón. 61. Tehuantepec. 62.
+Bisilana. 63. Santa Lucía. 64. Cerro de Arenal. 65. Cerro de San Pedro.
+66. La Concepción. 67. Tenango. 68. San Antonio. 69. Huilotepec. 70.
+Salina Cruz.]
+
+[Illustration: FIG. 2. Topographic profile of the Isthmus of
+Tehuantepec showing major localities along the Trans-isthmian Highway
+and major types of vegetation. Vertical exaggeration approximately 165
+times.]
+
+The central ridges extend from the Río Jaltepec southward to within 40
+kilometers of the Pacific coast. It is in this area that the continuity
+of the high ridges and volcanic peaks, which extend nearly the entire
+length of the Americas, is interrupted at a point almost directly in
+line with the shortest distance between the two oceans. The northern
+part of this central region consists of hills dissected by tributaries
+of the Río Coatzacoalcos; the principal ones from north to south
+are--Río Jaltepec, Río Tortuguero, Río Sarabia, and Río Malatengo. The
+plains of Chivela are south of these rivers and lie at an elevation of
+about 200 meters; at the southern edge of these plains a range of hills
+rises to 250 to 400 meters above sea level. These hills drop abruptly
+to the Plains of Tehuantepec. In the northern and central parts of this
+central region the rocks are granitic; the hills to the south of the
+Plains of Chivela are limestone.
+
+The Pacific Coastal Plain or Plains of Tehuantepec have a maximum width
+of about 30 kilometers. From the base of the hills at an elevation of
+about 75 meters the plains slope gradually to the sea. To the west of
+the Río Tehuantepec and to the east of the Plains of Tehuantepec at the
+base of the Sierra Madre de Chiapas, the coastal plain becomes much
+narrower; in these places the continuity of the plain is frequently
+interrupted by low north-south ridges extending outward from the
+mountains or by isolated hills. The soil is poor, varying from volcanic
+rock to gravel and sand.
+
+
+_Climate_
+
+The prevailing winds are from the north across the Gulf of Mexico.
+These moisture-laden winds precipitate most of their moisture north of
+the central ridges. This results in high rainfall on the northern
+slopes and Gulf Coastal Plain and relatively little rainfall on the
+southern slopes and the Pacific Coastal Plain. Precipitation is cyclic;
+there is a marked wet and a dry season throughout the region, but this
+is most noticeable on the Pacific lowlands (Fig. 3). At Salina Cruz on
+the Pacific Ocean the average annual rainfall is 1040 mm. (Contreras,
+1942); of this amount, only 15 mm. falls from November through April.
+On the Gulf Coastal Plain (Minatitlán station) the average annual
+rainfall is 3085 mm. In this region the driest months are February
+through May, during which time 236 mm. of rain falls. At Salina Cruz
+the wettest month is June; at Minatitlán it is September. There is
+little variation in temperature throughout the isthmus; the average
+annual temperature at Salina Cruz is 26.6° C.; that at Minatitlán is
+26.2° C. During the winter when masses of air from the arctic move
+southward into the Great Plains of the United States, cool winds blow
+across the isthmus. These are usually accompanied by overcast sky and
+sometimes a slight amount of precipitation. These "nortes" may cause a
+drop in temperature of about six to eight degrees in a few hours.
+
+[Illustration: FIG. 3. Climatographs for Minatitlán, Veracruz, and
+Salina Cruz, Oaxaca, based on data given by Contreras (1942). Plotted
+points are for mean monthly temperatures and rainfall; months are
+indicated by numbers.]
+
+
+_Vegetation_
+
+The topography and climate combine to produce drastically different
+types of climax vegetation on the northern and southern lowlands of the
+isthmus. The picture is somewhat complicated by the savannas on the
+Gulf Coastal Plain, which, as will be shown later, are dependent upon
+edaphic features more than climatic conditions. The following brief
+account of the vegetation in the Isthmus of Tehuantepec is based on
+data provided by Williams (1939) and Goldman (1951), supplemented by
+personal observations. The purpose of this description is not to
+analyze the flora of the isthmus, but to give the reader a picture of
+this aspect of the biota of the major environments with which I shall
+be concerned in the ensuing discourse on the amphibians of the region.
+The three divisions of the isthmus recognized in the account of the
+physiography serve equally well in describing the vegetation. Those
+divisions are as follows:
+
+Gulf Lowlands
+
+On the lowlands north of the continental divide and extending to the
+Gulf of Mexico are three major types of vegetation--tropical
+rainforest, arid tropical scrub forest, and savanna. Aside from these,
+there are marshes and lagoons near the coast.
+
+On the coastal dunes there are thickets of sea grape, patches of
+_Cenchrus_, and clumps or scattered _Opuntia_. The lagoons are bordered
+by mangrove thickets made up primarily of _Lonchocarpus hondurensis_.
+In the marshes along the lower Río Coatzacoalcos and Río Papaloapan the
+tall tough grass, _Gynerium sagittatum_, is common.
+
+According to Beard (1953: 291) the development of savanna vegetation is
+dependent upon soil, topography, and drainage. Level regions having
+permeable soil horizons lying on top of an impermeable horizon provide
+poor drainage. In most savanna regions in the Americas the grasslands
+become waterlogged or even partly flooded during the rainy season and
+desiccated in the dry season. Many ecologists and phytogeographers have
+postulated that savannas are either man made or are examples of a fire
+climax. Beard (_op. cit._: 203) provided multitudinous evidence that
+the association of savanna vegetation and certain types of edaphic and
+topographic conditions was so strongly marked that grassland is the
+natural vegetation in these areas.
+
+Savannas are scattered through southern Veracruz eastward to British
+Honduras. These usually are grasslands having scattered trees or clumps
+of trees around depressions, which may contain water throughout the
+year (Pl. 1, fig. 1). According to Williams (_op. cit._), the most
+common trees in the savannas in southern Veracruz are _Ceiba
+pentandra_, _Chlorophora tinctoria_, and _Byrsonima crassifolia_.
+
+Lying in a rain shadow cast by the Tuxtlas and on sandy and
+well-drained soils is a dense xerophytic forest. The crown of this
+deciduous forest usually is little more than ten to twelve meters above
+the ground (Pl. 1, fig. 2). Conspicuous trees in this scrub forest are
+_Acacia cornigera_, _Bauhinia latifolia_, _Calliandra bijuga_, _Cassia
+laevigata_, _Guazuma ulmifolia_, and various species of _Bursera_.
+
+The most extensive type of vegetation on the Gulf Coastal Plain is a
+tall evergreen forest resembling tropical rainforest. Although this
+forest is made up of many species of trees that are characteristic of
+true rainforest, the forest on the Gulf Coastal Plain cannot be
+classified as true rainforest, neither by the climatic conditions, nor
+the structure of the forest. The seasonal variation in rainfall
+probably is the chief factor in hindering the development of a
+rainforest climax vegetation. Usually a minimum of 65 mm. of rainfall
+each month is considered essential for the development of true
+rainforest. At Minatitlán the average rainfall for March (39 mm.) and
+April (36 mm.) is far below this minimum. Structurally, this forest has
+a crown about 30-35 meters above the ground but individual trees rising
+five meters or more above the crown (Pl. 2, figs. 1-2). There is no
+clear stratification within the forest; in many parts of it there are
+dense growths of bushes, small trees, and palms. The forest on the Gulf
+Coastal Plain, therefore, most properly might be referred to as a
+quasi-rainforest, a term that has been applied to other such forests in
+tropical America.
+
+Among the abundant and dominant trees in this forest are _Swietenia
+macrophylla_, _Calophyllum brasiliense_, _Achras zapota_, _Ceiba
+pentandra_, _Castilla elastica_, _Cedrela mexicana_, _Tabebuia
+Donnell-Smithi_, _Calocarpum mammosum_, _Bombax ellipticum_, and a
+variety of _Ficus_. Epiphytes and Ilianas are abundant.
+
+Central Ridges
+
+The vegetation of the central ridges of the isthmus is, for the most
+part, transitional between the tall rainforest of the Gulf Coastal
+Plain and the low xerophytic scrub forest of the semi-arid Pacific
+Coastal Plain. On the northern slopes of the ridges the rainforest is
+more poorly developed than on the plains to the north. Many of the same
+species of trees are present, including _Ceiba pentandra_, _Cedrela
+mexicana_, _Swietenia macrophylla_, and _Ficus_ sp.; nevertheless,
+these seldom are as large as members of the same species in the forest
+on the plains. Other species present on the forested slopes include
+_Tabebuia Donnell-Smithi_, _Zanthoxylum melanostictum_, _Pithecolobium
+arboreum_, and a species of _Pterocarpus_. The structure of this forest
+differs from that on the Gulf Coastal Plain in that there is no
+continuous upper canopy and there is a dense undergrowth (Pl. 3, fig.
+1). This type of forest extends from Mogoñe southward to about Matías
+Romero.
+
+In the vicinity of Matías Romero open pine-oak forest (_Pinus caribaea_
+and _Quercus_ sp.) is found on some ridges as low as 250 meters above
+sea level.
+
+On the Plains of Chivela in the southern part of the central region
+the vegetation takes on a semi-arid appearance, especially in a savanna
+on the plains. Clumps of small trees and bushes, consisting of _Croton
+nivea_, _Cordia cana_, _Jacquinia aurantiaca_, _Calycophyllum
+candidissimum_, and _Cassia emarginata_, are scattered on a grassy
+plain, from which rise widely-spaced palms of an unknown species (Pl.
+3, fig. 2).
+
+Pacific Coastal Plain
+
+The vegetation of the Pacific lowlands definitely is semi-arid in
+character. Most of the trees are deciduous, thorny, and short. During
+the dry season the landscape presents a barren appearance, but shortly
+after the first summer rains dense green foliage appears (Pl. 4, figs.
+1 and 2). Between Juchitán and La Ventosa few trees are more than two
+meters high (Pl. 5, fig. 1). In many areas the trees and bushes form an
+almost impenetrable tangle, whereas on especially rocky soils or on
+slopes those plants are more widely spaced. Abundant and widespread
+species of trees on the Plains of Tehuantepec include _Acacia
+cymbispina_, _Prosopis chilensis_, _Caesalpinia coriaria_, _Caesalpinia
+eriostachys_, _Celtis iguanaea_, _Cordia brevispicata_, _Jatropha
+aconitifolia_, and _Crescentia alata_.
+
+Montane Vegetation
+
+In order to illustrate the interruption of subtropical and temperate
+types of vegetation by the lowlands of the Isthmus of Tehuantepec, it
+is necessary to digress for a moment from the isthmus and consider the
+types of vegetation present on the adjacent highlands. On the higher
+peaks, such as Cerro de Zempoaltepetl, above about 2500 meters is fir
+forest (_Abies religiosa_); lower on the slopes are extensive pine
+forests, which on some slopes are mixed with oak or replaced entirely
+by oaks. Subtropical cloud forest, characterized by relatively cool
+temperatures and high humidity, is found at elevations usually between
+1000 and 1800 meters on the windward slopes of the Sierra Madre
+Oriental in Veracruz and northern Oaxaca and on the northern and
+southern slopes of the Chiapan-Guatemalan Highlands. None of these
+forest types is continuous across the Isthmus of Tehuantepec.
+
+
+_The Sierra de los Tuxtlas_
+
+Although actually located in the region of the Isthmus of Tehuantepec,
+the Sierra de los Tuxtlas, because of its isolated position, need not
+be considered in great detail in analyzing the distribution of animals
+inhabiting the lowlands of the isthmus. Nevertheless because some
+species living in the highlands adjacent to the isthmus also live in
+the Tuxtlas, this range is briefly described here. The Sierra de los
+Tuxtlas is a range of volcanos lying near the Gulf Coast in southern
+Veracruz between the mouths of the Río Papaloapan and the Río
+Coatzacoalcos. Volcán San Martín, the highest peak, rises above 1800
+meters. This range of volcanos is surrounded by lowlands, which
+immediately to the south and west are covered with savanna and in
+places by scrub forest. The luxuriant nature of the vegetation on these
+volcanos indicates that this range receives much more rainfall than the
+surrounding lowlands. Especially on the northern slopes, tropical
+rainforest is well developed; this is replaced at about 1200 meters by
+cloud forest. The southern and western slopes are drier, for the lower
+slopes are covered with a scrubby, but evergreen, forest.
+
+Detailed comments on the herpetofauna of the Tuxtlas have been omitted
+purposefully, for the reptiles and amphibians of the region currently
+are being studied by Douglas Robinson.
+
+
+
+
+GAZETTEER
+
+
+The following localities are those referred to in the text. The name of
+the locality (listed alphabetically by states) is followed by latitude,
+longitude, elevation, general description (town, ranch, etc.), and
+general type of habitat. Unless otherwise noted, distances are
+straight-line (airline) distances in kilometers. The localities have
+been plotted from the American Geographical Society's "Map of Hispanic
+America on the Scale of 1:1,000,000" (Millionth Map). Numbers in
+brackets identify the position of a locality on the accompanying map
+(Fig. 1).
+
+
+_Oaxaca_
+
+     Agua Caliente.--Lat. 16° 38'; long. 94° 48'; elev. 140 m. A
+     hot spring, 6.9 km. north of La Ventosa on the
+     Trans-isthmian Highway; arid scrub forest [43].
+
+     Arenal, Cerro de.--Lat. 16° 18'; long. 95° 32'; elev. 925 m.
+     (crest). A ridge northeast of Tenango; scrub forest on
+     slopes and pine-oak forest on top [64].
+
+     Barrio, El.--Lat. 16° 38'; long. 95° 07'; elev. 314 m. A
+     village about 10 kilometers southwest of Matías Romero;
+     transition between scrub forest and broadleaf hardwood
+     forest [38].
+
+     Bisilana.--Lat. 16° 20'; long. 95° 13'; elev. 35 m. A place
+     name for a former ranch at the edge of Tehuantepec; open
+     arid scrub forest [62].
+
+     Chivela.--Lat. 16° 20'; long. 95° 01'; elev. 195 m. A
+     village on the Trans-isthmian Railroad, 26 kilometers by
+     rail south of Matías Romero and on the western edge of the
+     semi-arid Plains of Chivela [40].
+
+     Concepción.--Lat. 16° 17'; long. 95° 29'; elev. 1200 m. A
+     ranch on the slopes of Cerro Arenal, east-northeast of
+     Tenango; dry pine-oak forest [66].
+
+     Coyol.--Exact position unknown; according to Smith and
+     Taylor (1950: 10), Coyol is "between San Antonio and Las
+     Cruces."
+
+     Donají.--Lat. 17° 13'; long. 95° 02'; elev. 90 m. A village
+     at Km. 155 on the Trans-isthmian Highway; rainforest [29].
+
+     Escurano.--Lat. 16° 25'; long. 95° 27'; elev. 500 m. A ranch
+     about 25 kilometers west-northwest of Tehuantepec; arid
+     scrub forest [51].
+
+     Guichicovi, San Juan.--Lat. 16° 58'; long. 95° 06'; elev.
+     250 m. A village on the north slopes of the isthmus, 12
+     kilometers north-northwest of Matías Romero; cleared
+     hardwood forest and coffee plantations [33].
+
+     Huilotepec.--Lat. 16° 14'; long. 95° 09'; elev. 30 m. A
+     small village on the Río Tehuantepec, 13 kilometers
+     south-southeast of Tehuantepec; open arid scrub forest [69].
+
+     Ixtepec.--Lat. 16° 34'; long. 95° 06'; elev. 60 m. A town
+     and railroad junction on the northwestern edge of the Plains
+     of Tehuantepec; arid scrub forest [45].
+
+     Juchitán.--Lat. 16° 26'; long. 95° 02'; elev. 15 m. A town
+     on the Plains of Tehuantepec, 22 kilometers by road
+     east-northeast of Tehuantepec; arid scrub forest [50].
+
+     Limón.--Lat. 16° 20'; long. 95° 29'; elev. 600 m. A former
+     agrarian colony and now a small ranch about 27 kilometers
+     west of Tehuantepec; arid scrub forest [60].
+
+     Matías Romero.--Lat. 16° 53'; long. 95° 02'; elev. 200 m. A
+     town on the Trans-isthmian Highway and railroad in the hills
+     near the crest of the isthmus; broadleaf hardwood forest and
+     open pine-oak forest [36].
+
+     Mixtequilla.--Lat. 16° 24'; long. 95° 18'; elev. 40 m. A
+     village on the Río Tehuantepec, northwest of Tehuantepec;
+     dense scrub forest [57].
+
+     Modelo, El.--Lat. 17° 07'; long. 94° 43'; elev. 200 m. An
+     old rubber plantation on the Río Chalchijapa, a tributary to
+     the Río Coatzacoalcos; rainforest [31].
+
+     Nanches, Portillo Los.--Lat. 16° 35'; long. 95° 37'; elev.
+     500 m. A place name, about 4 kilometers southeast of
+     Totolapilla; scrub forest [44].
+
+     Nizanda.--Lat. 16° 42'; long. 95° 02'; elev. 150 m. A
+     village on the Trans-isthmian Railroad between Chivela and
+     Ixtepec; dense scrub forest [42].
+
+     Nueva Raza.--Exact location unknown; according to Thomas
+     MacDougall, this locality is in the lowlands of northern
+     Oaxaca; rainforest.
+
+     Palmar.--Lat. 16° 43'; long. 94° 40'; elev. 300 m. A small
+     ranch on the west base of Cerro Atravesado; scrub forest
+     [39].
+
+     Papaloapan.--Lat. 18° 11'; long. 96° 06'; elev. 25 m. A
+     small village on the Río Papaloapan in northern Oaxaca; low
+     evergreen forest and savanna [11].
+
+     Princesa, La.--Lat. 16° 56'; long. 95° 02'; elev. 150 m. A
+     ranch on the northern slopes of the isthmus, 6 kilometers by
+     road north of Matías Romero; poorly developed rainforest
+     [34].
+
+     Quiengola, Cerro de.--Lat. 16° 24'; long. 95° 22'; elev. 900
+     m. (crest). A hill 15 kilometers west-northwest of
+     Tehuantepec; dense scrub forest on slopes and scattered
+     pines on top [55].
+
+     Salazar.--Lat. 16° 25'; long. 95° 20'; elev. 45 m. A ranch
+     on the Río Tehuantepec, northwest of Tehuantepec; dense
+     scrub forest [52].
+
+     Salina Cruz.--Lat. 16° 10'; long. 95° 12'; sea level. A port
+     on the Golfo de Tehuantepec; open arid scrub forest [70].
+     Collections were made in the vicinity of the town and in the
+     open scrub forest 2.4 kilometers north at an elevation of 20
+     meters.
+
+     San Antonio.--Lat. 16° 15'; long. 95° 22'; elev. 40 m. A
+     ranch about 25 kilometers west-southwest of Tehuantepec;
+     arid scrub forest [68].
+
+     San Pablo.--Lat. 16° 24'; long. 95° 18'; elev. 40 m. A ranch
+     on the Río Tehuantepec, northwest of Tehuantepec; dense
+     scrub forest [56]. Cerro San Pablo probably is the hill
+     north of this ranch; this is shown on some maps as Cerro de
+     los Amates.
+
+     San Pedro, Cerro de.--Lat. 16° 18'; long. 95° 28'; elev.
+     about 1100 m. (crest). A ridge about 24 kilometers west of
+     Tehuantepec and east of Cerro Arenal; scrub forest on slopes
+     and pine-oak forest on top [65].
+
+     Santa Efigenia.--Lat. 16° 25'; long. 94° 13'; elev. 500 m. A
+     ranch on the southern slopes of the Sierra Madre de Chiapas,
+     8 kilometers north-northwest of Tapanatepec; scrub forest.
+     Former home of Francis Sumichrast [53].
+
+     Santa Lucía.--Lat. 16° 18'; long. 95° 28'; elev. 800 m. A
+     place name for a former ranch on the east slopes of Cerro
+     Arenal; scrub forest [63].
+
+     Santa María Chimalapa.--Lat. 16° 55'; long. 94° 42'; elev.
+     296 m. A village on the Río de los Milagros, a tributary to
+     the Río Coatzacoalcos; rainforest [35].
+
+     Santiago Chivela.--Lat. 16° 42'; long. 94° 53'; elev. 200 m.
+     A village on the Trans-isthmian Highway, 13.4 kilometers by
+     road south of Matías Romero; dry, grassy plains and
+     scattered clumps of scrubby trees and palms [41].
+     Collections were made in the vicinity of the village and at
+     a rocky stream, 11 kilometers south on the Trans-isthmian
+     Highway at an elevation of 230 m.
+
+     Santo Domingo (Petapa).--Lat. 16° 50'; long. 95° 08'; elev.
+     225 m. A village about 13 kilometers west-southwest of
+     Matías Romero; semi-arid scrub forest [37].
+
+     Sarabia.--Lat. 17° 04'; long. 95° 02'; elev. 100 m. A
+     village 25 kilometers north of Matías Romero on the
+     Trans-isthmian Highway; rainforest [32]. Collections were
+     made in the vicinity of the village and in the rainforest
+     along the Río Sarabia, 5 kilometers north of the village at
+     an elevation of 80 meters.
+
+     Tapanatepec.--Lat. 16° 32'; long. 94° 12'; elev. 90 m. A
+     town on the Pan-American Highway on the lower slopes of the
+     Sierra Madre de Chiapas; dense scrub forest [58].
+
+     Tehuantepec.--Lat. 16° 20'; long. 95° 14'; elev. 35 m. A
+     large town on the Plains of Tehuantepec; scrub forest [61].
+     Collections were made in the vicinity of the town and in the
+     dense scrub forest 8.6 kilometers west at an elevation of 85
+     meters and 14 kilometers west at an elevation of 120 meters.
+
+     Tenango.--Lat. 16° 16'; long. 95° 30'; elev. 1100 m. A town
+     in the mountains about 40 kilometers west-southwest of
+     Tehuantepec; scrub forest [67].
+
+     Tequisistlán.--Lat. 16° 24'; long. 95° 37'; elev. 190 m. A
+     village in the valley of the Río Tequisistlán, a tributary
+     to the Río Tehuantepec; dense scrub forest [54]. Most
+     collections were made about one kilometer north of the
+     village where the Pan-American Highway crosses the Río
+     Tequisistlán.
+
+     Tolosita.--Lat. 17° 12'; long. 95° 03'; elev. 80 m. A
+     village on the Río Tortuguero near the Trans-isthmian
+     Highway; rainforest [30].
+
+     Tres Cruces.--Lat. 16° 26'; long. 95° 51'; elev. 750 m. A
+     ranch near the Pan-American Highway, 70 kilometers by road
+     west-northwest of Tehuantepec; dense scrub forest [49].
+
+     Tuxtepec--Lat. 18° 06'; long. 96° 05'; elev. 80 m. A town on
+     the Río Papaloapan in northern Oaxaca; low evergreen forest
+     [12].
+
+     Ubero.--Lat. 17° 18'; long. 95° 00'; elev. 80 m. A lumber
+     camp and railroad station, 8.5 kilometers south of the Río
+     Jaltepec on the Trans-isthmian Highway; rainforest [28].
+
+     Unión Hidalgo.--Lat. 16° 27'; long. 94° 48'; elev. 7 m. A
+     village on the railroad, 20 kilometers east-northeast of
+     Juchitán; open scrub forest [48].
+
+     Ventosa, La.--Lat. 16° 30'; long. 94° 51'; elev. 25 m. A
+     village at the junction of the Pan-American and
+     Trans-isthmian highways; open scrub forest [46].
+
+     Zanatepec.--Lat. 16° 28'; long. 94° 22'; elev. 80 m. A
+     village on the Pan-American Highway at the eastern edge of
+     the Plains of Tehuantepec; dense scrub forest [47]. Most
+     collections were made in the scrub forest 5 to 8 kilometers
+     west-northwest of the village.
+
+     Zarzamora.--Lat. 16° 21'; long. 95° 48'; elev. 800 m. A
+     ranch between La Reforma (16 kilometers west of
+     Tequisistlán) and Santa María Ecatepec; scrub forest with
+     oaks on higher ridges [59].
+
+
+_Veracruz_
+
+     Acayucan.--Lat. 17° 57'; long. 94° 55'; elev. 160 m. A large
+     town on the Trans-isthmian Highway; rainforest [21].
+     Collections were made in the vicinity of the town, but
+     principally at Rancho Las Hojitas, 7 kilometers northwest of
+     town at an elevation of 150 meters.
+
+     Alvarado.--Lat. 18° 47'; long. 95° 47'; sea level. A fishing
+     village at the mouth of the Río Papaloapan; coastal dunes
+     and marshes [1]. Most collections were made 1-3 kilometers
+     southeast of the village in marshes on the leeward side of
+     the coastal dunes.
+
+     Amatitlán.--Lat. 18° 26'; long. 95° 45'; elev. 4 m. A
+     village on the bank of the Río Papaloapan; savanna and sugar
+     plantations [6].
+
+     Aquilera.--Lat. 17° 48'; long. 95° 01'; elev. 150 m. A
+     village 21 kilometers southwest of Acayucan on the
+     Trans-isthmian Highway; rainforest [22].
+
+     Ayentes.--Lat. 18° 10'; long. 94° 26'; elev. 2 m. A railroad
+     station on the east bank of the Río Coatzacoalcos, across
+     the river from the city of Coatzacoalcos; scrub forest and
+     marshes [17].
+
+     Berta.--Lat. 18° 07'; long. 94° 27'; elev. 5 m. A ranch just
+     south of Coatzacoalcos; scrub and low evergreen forest [15].
+
+     Chacaltianguis.--Lat. 18° 18'; long. 95° 52'; elev. 5 m. A
+     village on the Río Papaloapan; savanna [8].
+
+     Ciudad Alemán.--Lat. 18° 13'; long. 96° 07'; elev. 30 m. A
+     new government town, headquarters of the Comisión del
+     Papaloapan; scrub and low evergreen forest [10].
+
+     Coatzacoalcos (formerly Puerto México).--Lat. 18° 10'; long.
+     94° 27'; elev. 2 m. A seaport at the mouth of the Río
+     Coatzacoalcos; scrub on coastal dunes; marshes and low
+     evergreen forest inland [16]. Most collections are from the
+     forest-savanna ecotone, 8 kilometers southwest of town.
+
+     Cosamaloapan.--Lat. 18° 22'; long. 95° 50'; elev. 4 m. An
+     agricultural town on the Río Papaloapan; savanna and sugar
+     plantations [7].
+
+     Cosoleacaque.--Lat. 17° 59'; long. 94° 38'; elev. 55 m. A
+     village 8 kilometers by road west of Minatitlán; savanna
+     [19].
+
+     Cuatotolapam.--Lat. 18° 08'; long. 95° 16'; elev. 13 m. A
+     village on the Trans-isthmian Railroad; savanna and low
+     evergreen forest along streams [13].
+
+     Hueyapan.--Lat. 18° 08'; long. 19° 09'; elev. 85 m. A town
+     32 kilometers by road northwest of Acayucan; savanna and low
+     evergreen forest [14]. Collections were made in the vicinity
+     of the town and from forest 10 kilometers southeast of town
+     at an elevation of 135 meters.
+
+     Jesús Carranza (formerly Santa Lucrecia).--Lat. 17° 27';
+     long. 95° 02'; elev. 80 m. A town and railroad junction in
+     the middle of the isthmus; rainforest [26]. Most of
+     Dalquest's specimens came from varying distances from Jesús
+     Carranza along the Río Coatzacoalcos and its tributaries.
+
+     Minatitlán.--Lat. 17° 58'; long. 94° 32'; elev. 15 m. An oil
+     refinery center on the Río Coatzacoalcos; savanna [20].
+
+     Naranjo.--Lat. 17° 35'; long. 95° 07'; elev. 100 m. A
+     village on the Trans-isthmian Highway, 45 kilometers south
+     of Acayucan; rainforest and palm forest [24].
+
+     Novillero.--Lat. 18° 16'; long. 95° 59'; elev. 10 m. A
+     village on the Río Papaloapan; scrub forest and grassland
+     [9].
+
+     Oaxaqueña, La.--Lat. 17° 26'; long. 94° 53'; elev. 80 m. A
+     hacienda on the Río Coatzacoalcos about 12 kilometers east
+     of Jesús Carranza; rainforest [27].
+
+     Playas, Río de las.--Lat. 18° 08'; long. 94° 07'; elev. 3 m.
+     The river (sometimes known as the Río Tonolá) forming the
+     boundary between the states of Veracruz and Tabasco;
+     rainforest [18].
+
+     San Lorenzo.--Lat. 17° 44'; long. 94° 42'; elev. 25 m. A
+     village on the Río Chiquito, about 30 kilometers southeast
+     of Acayucan; rainforest [23].
+
+     Suchil.--Lat. 17° 31'; long. 95° 03'; elev. 40 m. A village
+     on the Trans-isthmian Railroad, about 10 kilometers north of
+     Jesús Carranza; rainforest [25].
+
+     Tecolapan.--Lat. 18° 24'; long. 95° 18'; elev. 275 m. A
+     village on a small river of the same name in the western
+     foothills of Los Tuxtlas; rainforest [5].
+
+     Tejada, Lerdo de.--Lat. 18° 37'; long. 95° 31'; elev. 60 m.
+     An agricultural village, 35 kilometers by road
+     east-southeast of Alvarado; scrub forest, marshes, and sugar
+     plantations [2]. Collections were made in a marsh, 5
+     kilometers west-northwest of the village.
+
+     Tlacotalpan.--Lat. 18° 37'; long. 95° 42'; elev. 3 m. A town
+     at the confluence of the Río San Juan and Río Papaloapan;
+     marshes and sugar plantations [3].
+
+     Tula.--Lat. 18° 36'; long. 95° 22'; elev. 150 m. A village
+     near the western base of Los Tuxtlas; low evergreen forest
+     and marshes [4]. Collections were made in a marsh 3
+     kilometers northwest of the village.
+
+
+
+
+THE AMPHIBIAN FAUNA OF THE LOWLANDS
+
+
+In presenting an account of the amphibian fauna of the lowlands of the
+Isthmus of Tehuantepec three items must be considered:
+
+     1. The composition of the fauna.
+
+     2. The ecology of the fauna.
+
+     3. The distribution of the fauna.
+
+These items, together with similar data concerning the amphibians of
+the adjacent highlands, will form the basis for the subsequent
+discussion of the establishment of present patterns of distribution in
+the isthmian region.
+
+
+_Composition of the Fauna_
+
+The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 36 species definitely recorded from the area. These include
+one genus and species of caecilian, one genus, including three species
+of salamanders, and 14 genera and 32 species of anurans.
+
+In comparison with the known amphibian fauna of the forested and
+savanna portions of El Petén, Guatemala (Stuart, 1935 and 1958), we
+find that there are more species recorded from the isthmus than from El
+Petén. Stuart found only 20 species of amphibians in both forest and
+savanna habitats in El Petén. Of the 36 species of amphibians known
+from the isthmus, 28 occur on the Gulf lowlands and live in forest or
+savanna habitats.
+
+The geographic position of the isthmus with regard to major faunal
+areas in Middle America, and the diversity of the environment are
+important factors in understanding the presence of a large number of
+species of amphibians in the isthmus. The large number of species
+probably is a reflection of the diversity of the environment; this
+diversity is the result of fluctuation of climate, and thus
+environments, in the not too distant past. In no individual habitat,
+such as rainforest, savanna, or scrub forest, does the number of
+species approach the total for the region.
+
+
+_Ecology of the Fauna_
+
+In the preceding section on the description of the Isthmus of
+Tehuantepec I have outlined the major environments in the region. With
+respect to the distribution of amphibians we may recognize three major
+environments in the isthmus--rainforest, semi-arid scrub forest, and
+savanna. Each of these has varying combinations of physical and biotic
+factors that are important in the ecology of amphibians. Because of the
+importance of moisture, not only for the maintenance of life in these
+animals, but in most species their dependence on water for breeding
+purposes, this environmental factor is considered the most significant
+in the ecological distribution of amphibians. A second factor is the
+availability of necessary shelter, especially aestivation sites. These
+factors will be compared in the three major environments in the region.
+
+Moisture is present in the environment in the form of free water or
+atmospheric moisture. With respect to the latter, it is well known that
+dense shaded forests have a considerably higher relative humidity than
+do open plains or areas with only scattered trees. Thus, the
+rainforests of the isthmus are characterized by a much higher relative
+humidity than are the savannas or semi-arid scrub forests. Although
+with regard to rainfall there is a pronounced dry season in the regions
+supporting rainforest, there still remains considerable atmospheric
+moisture in this environment throughout the year. The dense foliage
+provides shade and protection from desiccating effects of wind and
+sunlight; furthermore the foliage contributes moisture by
+transpiration. The deep alluvial soils mixed with large quantities of
+organic matter (decaying leaves and rotting logs) maintain considerable
+quantities of moisture.
+
+Conversely, the savannas and scrub forests have little atmospheric
+moisture during the dry season. In the former habitat there are few
+trees to provide shade or moisture through transpiration; in the latter
+most of the trees lose their leaves during the dry season. Thus, these
+environments are desiccated by the dry winds and direct sunlight.
+Furthermore, the soils in these environments become dry and caked.
+There is little or no terrestrial matter to hold moisture.
+
+Free water in these environments is present in a variety of forms at
+different times of the year. During the dry season the more extensive
+marshes in the savannas persist; many ponds and most of the streams in
+the rainforest are permanent throughout the year. In the scrub forest
+all except the largest streams become dry during the dry season, and no
+ponds exist through the dry season. With the advent of the first heavy
+summer rains the stream beds fill with water, marshes expand, and many
+depressions become ponds (Pl. 5, fig. 2). At this time the amount of
+free water in the scrub forests and savannas greatly increases, much
+more so than that in the rainforests.
+
+Environments are vertically stratified in the rainforests. There is the
+deep alluvial soil, the ground litter of leaves and decaying logs, the
+low bushes and small trees, and finally the tall trees of the forest.
+Each of these provides certain types of shelter for amphibians. The
+moist soil and litter on the forest floor is an important microhabitat
+for fossorial and strictly terrestrial species. The dense foliage of
+the trees, tree holes, and bromeliads growing on the trees provide
+shelter for arboreal species. Arboreal and terrestrial bromeliads and
+the terrestrial elephant-ear plants (_Xanthosoma_) contain water in the
+axils of their leaves throughout the year and thus provide an important
+habitat for amphibians. The low, spiny, deciduous trees of the scrub
+forest and the grasses and scattered trees in the savannas provide
+little shelter. In the savannas there are depressions, some of which
+contain water throughout the year; these are often surrounded by trees
+providing refugia for amphibians during the dry season. In the scrub
+forest many species congregate along streams and in moist stream beds
+during the dry season.
+
+Now that the important ecological factors of the major environments
+have been outlined, we may examine the local distribution of amphibians
+in each of these. Beginning with the rainforest, we find only one
+fossorial species, _Gymnopis mexicanus_. A large number of species are
+found on the forest floor; characteristic inhabitants of the leaf
+litter are: _Bufo valliceps_, _Eleutherodactylus rhodopis_,
+_Microbatrachylus pygmaeus_, and _Syrrhophus leprus_. Other terrestrial
+amphibians usually are not scattered throughout the rainforest, as are
+those named immediately above, but instead inhabit areas of forest
+adjacent to ponds or streams; these species include: _Bufo marinus_,
+_Eleutherodactylus natator_, _Eleutherodactylus rugulosus_,
+_Leptodactylus labialis_, _Leptodactylus melanonotus_, _Rana palmipes_
+and _Rana pipiens_. The most striking ecological assemblage of
+amphibians in the rainforest is the arboreal group of species,
+including:
+
+     _Bolitoglossa occidentalis_
+     _Bolitoglossa platydactyla_
+     _Eleutherodactylus alfredi_
+     _Hyla baudini_
+     _Hyla ebraccata_
+     _Hyla loquax_
+     _Hyla microcephala martini_
+     _Hyla picta_
+     _Phrynohyas modesta_
+     _Phrynohyas spilomma_
+     _Phyllomedusa callidryas taylori_
+
+In the savannas _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and
+_Gastrophryne usta_ are fossorial species. _Bufo marinus_,
+_Leptodactylus melanonotus_, _Leptodactylus labialis_, _Rana palmipes_,
+and _Rana pipiens_ are found in the vicinity of permanent water in the
+savannas. Although the savanna habitat does not provide the ecological
+conditions for the existence of an arboreal fauna, many arboreal
+species from the surrounding rainforest utilize the extensive marshes
+and ponds in the savannas for breeding purposes. Thus, _Hyla baudini_,
+_Hyla microcephala martini_, _Hyla picta_, and _Phrynohyas spilomma_
+have been found breeding in savannas. In parts of savannas where clumps
+of trees surround depressions containing water throughout the year,
+individuals of the species named above, together with _Hyla loquax_ and
+_Phyllomedusa callidryas taylori_, may not only breed, but remain
+throughout the year.
+
+In the semi-arid scrub forest the same fossorial species as exist in
+the savannas are found. Likewise, _Bufo marinus_, _Leptodactylus
+labialis_, _Leptodactylus melanonotus_, and _Rana pipiens_ are found
+near permanent water. Terrestrial species in this semi-arid environment
+include _Bufo canaliferus_, _Bufo coccifer_, _Bufo marmoreus_,
+_Syrrhophus pipilans_, and _Diaglena reticulata_. Of these, _Syrrhophus
+pipilans_ sometimes inhabits low trees and bushes; the others may be
+fossorial. The arboreal species in the scrub forest include _Hyla
+baudini_, _Hyla robertmertensi_, _Hyla staufferi_, and _Phyllomedusa
+dacnicolor_.
+
+_Eleutherodactylus rugulosus_ and _Hylella sumichrasti_ live along
+streams in the scrub forest. _Hylella sumichrasti_ lays its eggs in
+these streams.
+
+In comparing the ecological differences in the amphibian assemblages in
+the three major habitats, the most obvious difference is the great
+percentage of arboreal species in the rainforest as compared with
+savanna and scrub forest. Only four arboreal species are found in the
+scrub forest, none in the savannas, but eleven in the rainforest.
+Likewise, there is an absence of ground-dwelling forms in the arid
+habitats; in the latter the only terrestrial species are those that
+are found near water. A possible exception is _Syrrhophus pipilans_.
+
+From the above analysis of ecological distribution we may see that the
+rainforest provides a variety of habitats for amphibians and that these
+habitats are suitable for amphibian life throughout the year. On the
+other hand, the savannas and scrub forests are characterized by extreme
+conditions of desiccation, a factor of considerable importance in
+limiting the ecological distribution of amphibians. However, there
+still is a diversity of amphibians in these semi-arid environments.
+Obviously, these species are adapted in various ways for survival
+during the dry season, at which time environmental conditions are such
+that the animals cannot carry on their normal activities.
+
+Although there is not an abundance of data concerning the seasonal
+activity of the fauna, what is available shows some interesting
+correlations with the environments. During the dry season in the scrub
+forest there is essentially no amphibian activity; an occasional _Rana
+pipiens_ may be seen along a river, or a _Bufo marinus_ may be seen at
+night. In the rainforest the terrestrial-breeding amphibians are active
+during the dry season. _Eleutherodactylus rugulosus_ is found at night
+or by day along streams. _Eleutherodactylus rhodopis_,
+_Microbatrachylus pygmaeus_, and _Bufo valliceps_ are active during the
+day; these plus _Bolitoglossa occidentalis_, _Bolitoglossa
+platydactyla_, _Eleutherodactylus alfredi_, _Eleutherodactylus
+natator_, and an occasional _Hyla_ are active at night.
+
+With the onset of the heavy summer rains and the subsequent formation
+of breeding ponds, amphibian activity reaches a peak. This is
+especially noticeable in the semi-arid environments, where during the
+dry season there is little activity.
+
+Among the anurans in the isthmus the four species of
+_Eleutherodactylus_, the two species of _Syrrhophus_, and the one
+species of _Microbatrachylus_ are either known, or presumed, to lay
+eggs on the ground; these develop directly into small frogs. All of the
+other anurans deposit their eggs in water or attach them to objects
+over water (_Phyllomedusa_); these hatch into tadpoles, which later
+metamorphose into frogs. _Hylella sumichrasti_ is known to breed only
+in streams. All of the other species breed in ponds, but at times some
+species deposit their eggs in streams; in this last group are _Bufo
+valliceps_, _Bufo marmoreus_, _Phyllomedusa callidryas taylori_, and
+_Rana pipiens_.
+
+Although the ecological data are incomplete, they do show that
+ecological conditions differ greatly in the three major environments,
+different species of amphibians inhabit these environments, and that
+the fauna is ecologically diversified in each environment.
+
+
+_Distribution of the Fauna_
+
+Plotting the distributions of species of amphibians known to live in
+the lowlands of the Isthmus of Tehuantepec results in an array of
+geographic patterns. These may be analyzed with respect to those
+species that are restricted either to the Gulf lowlands or the Pacific
+lowlands, or those that occur on both the Gulf and Pacific lowlands.
+Furthermore, the distributions may be analyzed with respect to those
+species whose ranges extend from México across the Isthmus of
+Tehuantepec into Central America, those that reach the isthmus from
+Central America but do not extend into México proper, and those that
+reach the isthmus from México but do not extend into Central America.
+It should be kept in mind that the following analysis is of the lowland
+inhabitants only. Species inhabiting the foothills and mountains will
+be discussed later.
+
+1. SPECIES RESTRICTED TO THE GULF LOWLANDS. Of the 36 species of
+amphibians recorded from the Isthmus of Tehuantepec, nine (25 per cent)
+are in this group. Four of these (_Eleutherodactylus alfredi_,
+_Syrrhophus leprus_, _Hyla loquax_, and _Hyla picta_) live in the Gulf
+lowlands to the east and to the west of the isthmus. Three others
+(_Hyla ebraccata_, _Hyla microcephala martini_ and _Phyllomedusa
+callidryas taylori_) are primarily Central American in their
+distribution and reach the northwestern limits of their ranges in the
+Gulf lowlands of the isthmus, whereas _Bolitoglossa platydactyla_ and
+_Eleutherodactylus natator_ reach the southern limits of their
+distributions in the isthmus.
+
+2. SPECIES RESTRICTED TO THE PACIFIC LOWLANDS. This group includes six
+species, or 17 per cent of the amphibian fauna of the isthmus. Two of
+these (_Bufo coccifer_ and _Syrrhophus pipilans_) range to the east and
+to the west of the isthmus on the Pacific lowlands. Two others (_Bufo
+canaliferus_ and _Hyla robertmertensi_) range from the isthmus into
+Central America, and _Diaglena reticulata_ and _Phyllomedusa
+dacnicolor_ range on the Pacific lowlands of México southeastward to
+the isthmus.
+
+3. SPECIES THAT OCCUR ON THE PACIFIC AND GULF LOWLANDS. This group
+includes 19 species, or 53 per cent of the total amphibian fauna. Of
+these, nine species (25 per cent of the entire amphibian fauna) are
+widespread throughout the lowlands of México and Central America; these
+are:
+
+     _Gymnopis mexicanus_
+     _Rhinophrynus dorsalis_
+     _Bufo marinus_
+     _Engystomops pustulosus_
+     _Leptodactylus labialis_
+     _Leptodactylus melanonotus_
+     _Hyla baudini_
+     _Hyla staufferi_
+     _Rana pipiens_
+
+Four species occur on the Gulf lowlands to the east and to the west of
+the isthmus, but on the Pacific lowlands they occur only to the east;
+this group includes _Bufo valliceps_, _Eleutherodactylus rhodopis_,
+_Phrynohyas modesta_, and _Phrynohyas spilomma_. Three species live to
+the east and to the west of the isthmus on the Pacific lowlands, but
+only to the west on the Gulf lowlands; these include _Eleutherodactylus
+rugulosus_, _Microbatrachylus pygmaeus_, and _Gastrophryne usta_.
+
+Six species that cross the isthmus live on the humid Gulf lowlands and
+on the humid lowlands of Chiapas and Guatemala, but not on the
+semi-arid Plains of Tehuantepec; these include _Bolitoglossa
+occidentalis_, _Eleutherodactylus rhodopis_, _Microbatrachylus
+pygmaeus_, _Phrynohyas modesta_, _Phrynohyas spilomma_, and _Rana
+palmipes_. Of these, _Microbatrachylus pygmaeus_ also occurs in
+scattered humid environments to the west of the isthmus on the Pacific
+lowlands.
+
+Two species are endemic to the isthmian region. _Bolitoglossa
+veracrucis_ is known only from the humid northern slopes of the
+isthmus. _Hylella sumichrasti_ occurs on the Pacific slopes of the
+isthmus and extends to the east into western Chiapas.
+
+In analyzing the distribution of the amphibians with respect to those
+that are restricted to either the Pacific or Gulf lowlands or those
+that cross the continental divide in the isthmus, we find that 25 per
+cent of the species are restricted to the Gulf lowlands, 17 per cent
+are restricted to the Pacific lowlands, and 53 per cent cross the
+isthmus. In analyzing the distribution patterns with respect to those
+that extend across the isthmus of Tehuantepec from east to west, we
+find that 14 per cent of the species do not extend east of the isthmus
+into Central America and that 19 per cent do not range west of the
+isthmus into México proper; 61 per cent of the species range to the
+east and to the west of the isthmus. Of the 36 species of amphibians
+inhabiting the isthmus only nine species (25 per cent) range across the
+isthmus, that is, occur on the Gulf and Pacific lowlands, and also
+range to the east and to the west of the isthmus. To these wide-ranging
+species the diversified environments of the isthmus do not present a
+barrier to distribution. The other 27 species (75 per cent) either do
+not cross the isthmus from east to west or from north to south; thus,
+probably in one way or another the isthmus presents a barrier to their
+distribution.
+
+
+
+
+THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS
+
+
+To amphibians inhabiting the foothills and mountains of southern México
+and northern Central America, the isthmus presents a great barrier to
+dispersal. For example, salamanders of the genus _Thorius_, the
+_mexicanus_ and _augusti_ groups of the genus _Eleutherodactylus_, the
+_bistincta_ group of the genus _Hyla_, and the genus _Tomodactylus_
+occur on the Mexican Plateau and southward into the mountains of
+Oaxaca. Nevertheless, no members of these groups are present in the
+Guatemalan-Chiapan Highlands. The genera _Chiropterotriton_,
+_Magnadigita_, _Pseudoeurycea_, and _Ptychohyla_, as well as the
+_eximia_ group of _Hyla_ are represented by different species in the
+Guatemalan-Chiapan Highlands than in the mountains of México on the
+other side of the isthmus. Several species of _Plectrohyla_ occur in
+the Guatemalan-Chiapan Highlands, but none is known from the Mexican
+Highlands, although one species occurs in the Tuxtlas.
+
+Living in the humid forests of the foothills are salamanders of the
+genus _Lineatriton_, frogs of the _spatulatus_ group of
+_Eleutherodactylus_, _Anotheca coronata_, _Hyla miotympanum_, and
+_Phyllomedusa moreleti_. All of these occur in the foothills of the
+Sierra Madre Oriental in eastern México and in Los Tuxtlas.
+_Lineatriton_, _Hyla miotympanum_, and the _spatulatus_ group of
+_Eleutherodactylus_ do not occur in the foothills of the
+Guatemalan-Chiapan Highlands; those amphibians reach the end of their
+ranges at the isthmus. _Phyllomedusa moreleti_ and _Anotheca coronata_
+are found in the northern foothills of the Guatemalan-Chiapan
+Highlands, and _Phyllomedusa moreleti_ is found in the foothills on the
+Pacific slopes of the Chiapan Highlands.
+
+Although the above analysis is not so detailed as that of the lowland
+inhabitants, it does show that all of the genera and species of
+amphibians known to inhabit the foothills and highlands adjacent to the
+isthmus, only two species of amphibians cross the isthmus from one
+highland mass to the other. Thus, it is evident that the Isthmus of
+Tehuantepec presents a great barrier to dispersal of these groups of
+amphibians.
+
+
+
+
+ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION
+
+
+From the foregoing analysis of geographical and ecological distribution
+in the Isthmus of Tehuantepec we may strive for an interpretation of
+the events that led to the establishment of patterns of distribution
+displayed not only by the amphibians, but other terrestrial vertebrates
+as well. The thesis that I am proposing below is based on the premise
+that in southern México and northern Central America climatic
+fluctuation during the Pleistocene was of sufficient magnitude to cause
+vegetational shifts, both vertically and latitudinally, resulting in
+the establishment of alternating continuous and discontinuous lowland
+and highland environments, although this climatic fluctuation was not
+so great as to eliminate tropical lowland environments from the region.
+I feel that the present patterns of distribution of the amphibians in
+the Isthmus of Tehuantepec may be explained on this premise.
+
+Many authors dealing with the herpetofauna of Middle America have
+followed Schuchert's (1935) suggestion of a seaway in the isthmus
+during the Cenozoic. Thus, Burt (1931), Duellman (1956, 1958a), Gloyd
+(1940), Oliver (1948), Smith and Laufe (1946), and Stuart (1941)
+employed the presence of a seaway to explain distribution and
+speciation in various genera. Durham, Arellano, and Peck (1952), Olson
+and McGrew (1941), and Stirton (1954) have provided geological evidence
+that there probably was no Cenozoic seaway in the Isthmus of
+Tehuantepec. Even if there were a seaway in the Pliocene or Miocene
+(the dating of this possible seaway is open to question), its presence
+is not necessary to explain the present patterns of distribution in the
+isthmus.
+
+In recent years the study of natural biotic environments, palynology,
+and Pleistocene chronology in Middle America has produced a wealth of
+data, which although still fragmentary begins to form a picture of past
+climatic events in that part of the world. Sedimentary studies by
+Hutchinson, Patrick, and Deevey (1956) and Sears, Foreman, and Clisby
+(1955) have provided evidence of drastic climatic shifts in México
+during the Pleistocene. Further evidence of bioclimatic fluctuation is
+provided by Martin and Harrell (1957) and Martin (1958); the latter has
+suggested that there was a displacement of the tropical zones in
+southern México and northern Central America by as much as 3000 feet
+during the glacial maximum. Much of the evidence of such drastic
+vertical shifts in environments is based on the presence of
+Pleistocene montane glaciers on Mexican volcanoes (White, 1956) and
+Chirripo in Costa Rica (Weyl, 1955). Dorf (1959) supports this idea of
+drastic climatic change.
+
+In his studies of the avifauna of México and Guatemala Griscom (1932
+and 1950) made an important issue of the continuity of the bird fauna
+in what he called the Subtropical Life-zone, which essentially consists
+of cloud forest, a widespread, but discontinuous, habitat on the Gulf
+(windward) slopes of the Mexican and Central American highlands at
+elevations between 1000 and 2000 meters. To account for this apparent
+uniformity in the avifauna Griscom hypothesized a continuity of cloud
+forest environment in the Pleistocene; this would result in the
+depression of cloud forests to the coastal lowlands and the
+displacement of tropical lowland environments far to the south in
+Central America. Stuart (1951) objected to this displacement of lowland
+tropical rainforest; he stated that a descent to sea level of a
+subtropical zone would have brought about either widespread
+extermination of the tropical fauna or acclimatization of that fauna to
+subtropical conditions.
+
+Although palynological studies and some faunal studies of subtropical
+and temperate animals suggest a drastic climatic fluctuation that might
+have eliminated tropical environments in southern México and northern
+Central America, there is much biological evidence indicating the
+existence of tropical environments in this region even during the
+glacial maximum. Especially significant is the diversity of species
+inhabiting the present tropical environments; many of these have
+differentiated from related taxa to the south.
+
+In the Pleistocene, climate fluctuated and vegetation shifted
+correspondingly in southern México and northern Central America. Most
+of the palynological studies and many studies of Pleistocene chronology
+deal with montane regions, either the Mexican Plateau or the mountains
+rising from the plateau. No such studies have been made in lowland
+tropical environments. During glacial advances the tropical lowland
+environments in México probably were not eliminated, for the great
+diversity of animals in these environments supports the hypothesis that
+they have been in existence for some time, although periodically they
+may have been discontinuous.
+
+In order to understand the nature of bioclimatological events in the
+Pleistocene in lowland tropical environments of southern México,
+certain factors that are of little importance in the interpretation of
+Pleistocene chronology in the highlands must be considered. These
+factors are: 1) climatic moderation by oceans, 2) fluctuation in sea
+level, and 3) fluctuation in level of the water table as affected by
+sea level.
+
+It is well-known that large bodies of water moderate the temperature on
+adjacent land. Furthermore, it is known that faunas of marine
+invertebrates shifted latitudinally in the Pleistocene; Trask, Phleger,
+and Stetson (1947) recorded cold-water Foraminifera then as far south
+as the Sigsbee Deep in the middle of the Gulf of Mexico. Large bodies
+of warm water, such as the Gulf of Mexico, Caribbean Sea, and Pacific
+Ocean of today, probably were not sufficiently cooled at the time of
+glacial advance to affect greatly the temperature of the winds blowing
+across them. Even if these bodies of water were somewhat cooler than
+now, the prevailing winds blowing from them onto the lowlands of México
+and northern Central America would have aided in maintaining relatively
+high temperatures there. These warm winds probably counteracted the
+cooling effect of glaciation in the lowlands and thereby maintained
+tropical conditions near the seas.
+
+Although no adequate studies of Pleistocene beach lines have been made
+in southern México, such information is available for peninsular
+Florida on the other side of the Gulf of Mexico (Cooke, 1945).
+Fluctuation in sea level in the Pleistocene has been used by Hubbell
+(1954), Goin (1958), and Duellman and Schwartz (1958) to explain
+present patterns of distribution of animals in Florida. If Cooke's
+interpretations can be applied to the western side of the Gulf of
+Mexico, even generally, it would be supposed that sea level varied from
+about 300 feet lower than at present during the Illinoian Glacial
+Period to about 275 feet higher than at present during the Aftonian
+Interglacial Period. Lowering of sea level would expand the lowlands in
+the isthmus; rising sea level would restrict them, leaving only the
+central ridges and many islands in the isthmus, but never forming a
+seaway between the Gulf of Mexico and the Pacific Ocean.
+
+Probably the level of the water table in the coastal lowlands and the
+gradients of the streams in the lowlands and foothills was closely
+correlated with fluctuation in sea level. If sea level fluctuated as
+much as 575 feet in the Pleistocene, changes in the level of the water
+table must have been of considerable magnitude.
+
+During times of glacial advances the lowlands of the isthmus probably
+were more extensive and had more semi-arid tropical environments than
+at present, with patches of rainforest existing in sheltered valleys
+along the major streams. In the course of bio-climatic fluctuation the
+semi-arid environments (scrub forest and/or savanna) were continuous at
+times from the Pacific lowlands across the isthmus to the Gulf
+lowlands. At those times such typical inhabitants of the semi-arid
+environments as _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and
+_Hyla staufferi_ could have made their way across the isthmus. At times
+of most extensive glaciation, such as the Illinoian, temperatures in
+the isthmus probably were low enough to permit the growth of pine-oak
+forest and cloud forest continuously across the central ridges from the
+Mexican to the Chiapan-Guatemalan highlands. At those times such
+highland members of the fauna as _Chiropterotriton_, _Pseudoeurycea_,
+_Magnadigita_, and the _eximia_ group of _Hyla_ could have crossed the
+isthmus. During Wisconsin time, climate probably fluctuated less than
+during previous glaciations; probably no montane environments, except
+cloud forest, were represented in the isthmus during the Wisconsin.
+Even at this relatively late date such animals as _Lineatriton
+lineola_, _Anotheca coronata_, and _Phyllomedusa moreleti_ could have
+crossed the isthmus.
+
+During the interglacial periods, which in the isthmian region were
+characterized by warmer temperatures, higher sea level and consequently
+more restricted areas of lowlands, and possibly more rainfall than in
+the glacial periods, the continuity of pine-oak forest and cloud forest
+from east to west across the isthmus was interrupted. Probably, too,
+the semi-arid environments were restricted, and the rainforests were
+more widespread. At those times animals now inhabiting the rainforests
+of the Gulf lowlands and those inhabiting the Pacific lowlands of
+Chiapas and Guatemala could have crossed the isthmus. In this group are
+species such as _Bolitoglossa occidentalis_, _Eleutherodactylus
+rhodopis_, _Microbatrachylus pygmaeus_, and _Rana palmipes_.
+
+The amount of differentiation in isolated populations of amphibians in
+southern México and northern Central America gives some idea of
+relative lengths of time of isolation from related populations. Those
+populations inhabiting high mountain environments on either side of the
+isthmus are specifically distinct. Some populations inhabiting cloud
+forests lower on the mountains are specifically distinct from related
+populations on the other side of the isthmus; between others there is
+no recognizable differentiation. Even though many populations are
+isolated from other populations of the same species in the lowlands of
+the isthmus, there is no apparent speciation. This indicates that the
+lowland environments and their inhabitants have been isolated from one
+another for a shorter time than have the highland environments and
+their inhabitants.
+
+
+
+
+ACCOUNTS OF SPECIES
+
+
+For each species of amphibian known to occur in the lowlands of the
+Isthmus of Tehuantepec, localities where one or more specimens were
+collected are listed, and variation, ecology, and life histories are
+discussed. A total of 2833 specimens has been examined for the purposes
+of this study. Individual specimens cited in the text are listed with
+catalogue numbers and abbreviations of the name of the museum, as
+follows:
+
+     AMNH  American Museum of Natural History
+     KU    University of Kansas Museum of Natural History
+     MCZ   Museum of Comparative Zoology, Harvard College
+     UIMNH University of Illinois Museum of Natural History
+     UMMZ  University of Michigan Museum of Zoology
+     USNM  United States National Museum
+
+
+=Gymnopis mexicanus mexicanus= Duméril and Bibron
+
+     _Oaxaca_: El Barrio (3); Matías Romero; Tehuantepec (2).
+     _Veracruz_: Cosamaloapan; Cuatotolapam (2).
+
+The two specimens from Cuatotolapam were collected by Ruthven in an
+area of mixed savanna and forest. The three specimens (USNM 30535-7)
+listed above from El Barrio were collected by Sumichrast; possibly they
+came from another locality. The city of Tehuantepec is divided into
+seven districts called "barrios." The two specimens listed from
+Tehuantepec (MCZ 1604) merely bear the data "Tehuantepec, Mexico." They
+may have come from the town, the district, or from anywhere in the
+isthmus. The specimen from Matías Romero has 109 primary and 67
+secondary annuli, a length of 400 mm., and a diameter of 19 mm.; the
+one from Cosamaloapan has 106 primary and 58 secondary annuli, a length
+of 397 mm., and a diameter of 19 mm. Data on the other specimens were
+recorded by Dunn (1942:475).
+
+
+=Bolitoglossa occidentalis= Taylor
+
+     _Oaxaca_: Río Sarabia (2); Ubero. _Veracruz_: La Oaxaqueña;
+     14 km. E of Suchil.
+
+The specimens from Oaxaca are only tentatively assigned to
+_occidentalis_. All are immature and lack maxillary teeth. Taylor
+(1941:147) stated that the maxillary teeth are absent in young
+_occidentalis_. One from Río Sarabia is a male with a body-length of 29
+mm. and a tail-length of 22 mm. The dorsum is reddish brown streaked
+with dark gray; the venter is dark gray. Two small individuals (one
+from Sarabia and one from Ubero) have body-lengths of 19 and 21 mm. and
+tail-lengths of 10.5 and 11 mm. In life they were pale yellowish tan
+above with a brown triangular mark on the occiput, but with no
+middorsal stripe. Both were found in the axils of elephant ear plants
+(_Xanthosoma_).
+
+This species has been noted by Goodnight and Goodnight (1956:146) on
+the Atlantic lowlands at Palenque, Chiapas, and by Shannon and Werler
+(1955:362) at several localities in Los Tuxtlas, Veracruz. I have
+collected it at Vista Hermosa on the eastern slopes of the Sierra Madre
+Oriental above Tuxtepec in northern Oaxaca. Both _B. occidentalis_ and
+_B. rufescens_ have been reported from Palenque, Chiapas (Taylor and
+Smith, 1945:547). Reëxamination of specimens from northern Chiapas and
+Tabasco is needed to verify the sympatric occurrence of these two
+similar species.
+
+
+=Bolitoglossa platydactyla= Tschudi
+
+     _Oaxaca_: La Oaxaqueña; Tolosita (2). _Veracruz_: Acayucan;
+     Cuatotolapam; 25 km. ESE of Jesús Carranza; 14 km. E of
+     Suchil; 2.7 km. N of Tula.
+
+Known only from the Gulf lowlands in the isthmian region, this species
+has been taken in a variety of habitats within the humid forest area:
+under outer leaves of banana plants, under a rock along a stream, under
+a log in a plowed field, and on a reed in a pond at night. Three adult
+males have an average snout-vent length of 44 mm. and a tail-length of
+41 mm. In life the color of the dorsum varied from orange-yellow to
+orange-tan, usually being more orange on the tail. The iris was a
+reddish orange.
+
+
+=Bolitoglossa veracrucis= Taylor
+
+     _Veracruz_: 35 km. SE of Jesús Carranza (21).
+
+This species is known only from the type series collected at night on a
+limestone cliff by Walter W. Dalquest. If this salamander is restricted
+to this type of habitat, it should be found in the region of extensive
+limestone outcroppings in northern Chiapas and southern Tabasco.
+
+
+=Rhinophrynus dorsalis= Duméril and Bibron
+
+     _Oaxaca_: Ixtepec; Limón; Salina Cruz (18); Tehuantepec
+     (57); Tuxtepec (3). _Veracruz_: Amatitlán (3); Cosamaloapan
+     (5); Novillero (2); San Lorenzo.
+
+This species inhabits the scrub forests of the Pacific coastal plain
+and the savannas in southern Veracruz; apparently it does not occur in
+rainforest. Consequently, its distribution in the isthmus is
+discontinuous.
+
+PLATE 1
+
+[Illustration: FIG. 1. Savanna about 75 kilometers east of
+Coatzacoalcos, Veracruz. Photograph by L. C. Stuart.]
+
+[Illustration: FIG. 2. Low scrub forest near Alvarado, Veracruz.
+Photograph by L. C. Stuart.]
+
+PLATE 2
+
+[Illustration: FIG. 1. Rainforest near Tolosita, Oaxaca. March, 1956.]
+
+[Illustration: FIG. 2. Rainforest along the Río Sarabia, Oaxaca. March,
+1956.]
+
+PLATE 3
+
+[Illustration: FIG. 1. Transition forest near La Princesa, Oaxaca.
+March, 1956.]
+
+[Illustration: FIG. 2. Palm Savanna on the Plains of Chivela, Oaxaca.
+March, 1956.]
+
+PLATE 4
+
+[Illustration: FIG. 1. Scrub forest on the Plains of Tehuantepec in dry
+season. March, 1956.]
+
+[Illustration: FIG. 2. Scrub forest on the Plains of Tehuantepec in
+rainy season. View toward the north. In the distance is the Continental
+Divide in the hills of the Isthmus. July, 1958.]
+
+PLATE 5
+
+[Illustration: FIG. 1. Low, dense scrub forest near La Ventosa, Oaxaca.
+July, 1958.]
+
+[Illustration: FIG. 2. Temporary pond in scrub forest north of Salina
+Cruz, Oaxaca. July 7, 1958. _Rhinophrynus dorsalis_, _Bufo marmoreus_,
+and _Diaglena reticulata_ were breeding here the previous night.]
+
+PLATE 6
+
+[Illustration: FIG. 1. Calling male of _Rhinophrynus dorsalis_,
+photographed in a pond north of Santa Cruz, Oaxaca, on July 6, 1958.
+× 2/3.]
+
+[Illustration: FIG. 2. Color pattern variation in two adults of _Bufo
+canaliferus_ from Juchitán, Oaxaca. × 2/3.]
+
+PLATE 7
+
+[Illustration: FIG. 1. Calling male of _Engystomops pustulosus_,
+photographed in a pond west of Tehuantepec, Oaxaca, on July 5, 1956.
+× 2.]
+
+[Illustration: FIG. 2. Foamy egg mass of _Engystomops pustulosus_ at
+the edge of a pond west of Tehuantepec, Oaxaca. July 5, 1956. × 3/8.]
+
+PLATE 8
+
+[Illustration: FIG. 1. Calling male of _Diaglena reticulata_,
+photographed at a pond north of Salina Cruz, Oaxaca, on July 6, 1958.
+× 1/2.]
+
+[Illustration: FIG. 2. Clasping pair of _Diaglena reticulata_ at the
+edge of a pond north of Salina Cruz, Oaxaca, on July 6, 1958. × 1.]
+
+Breeding congregations were found after heavy rains at Tehuantepec on
+July 5, 1956, at Cosamaloapan, Novillero, and Amatitlán on July 26,
+1956, and at Salina Cruz on July 6, 1958. The call is a long "worrp"
+made while the male is floating on the surface of the pond. The small
+heads, small limbs, and greatly inflated bodies cause the calling males
+to resemble miniature caricature balloons (Pl. 6, fig. 1). Amplexus is
+inguinal. These toads are notably wary, even when calling. Often the
+beam of a flashlight or the slightest disturbance of the water will
+cause the males to stop calling. The body is deflated with one last
+nauseous note, and the frog sinks beneath the surface of the water and
+swims away with short slow kicks of the hind feet.
+
+
+=Bufo canaliferus= Cope
+
+     _Oaxaca_: Chivela; Salina Cruz; Santa Efigenia; Tapanatepec
+     (6); Tehuantepec (10); Zanatepec (4).
+
+This small toad apparently is restricted to the Pacific lowlands from
+the Isthmus of Tehuantepec eastward to Guatemala. At Zanatepec on July
+13, 1956, males were calling from a flooded field bordered by scrub
+forest. The call is a rather loud nasal racket. Living individuals vary
+greatly in coloration. Some have yellowish tan flanks and dorsum and an
+orange middorsal stripe; others have a pale red dorsum, yellow flanks,
+and a cream middorsal stripe (Pl. 6, fig. 2).
+
+
+=Bufo coccifer= Cope
+
+     _Oaxaca_: Juchitán (5); Tehuantepec.
+
+It is with some degree of hesitancy that these toads are referred to
+the species _coccifer_. Although these and other specimens from
+Guerrero and Michoacán display no striking differences from specimens
+from Costa Rica, Nicaragua, and southeastern Guatemala, the ranges of
+the populations are separated by a broad hiatus in Chiapas and
+Guatemala. Possibly this species has utilized the sub-humid corridor
+through northern Central America (Stuart, 1954) and subsequently
+disappeared from the corridor in Guatemala and Chiapas. Specimens of a
+_coccifer_-like toad collected by Stuart in the vicinity of
+Jacaltenango, Departamento Huehuetenango, Guatemala, are much larger
+than either the Central American or Mexican specimens of _coccifer_. A
+final commitment on the systematic status must await a thorough study
+of this group of toads.
+
+Males of this species were calling from a grassy rain-pool in open
+scrub forest at the edge of Juchitán on July 6, 1956. The call is a
+low "whirrr." The calling males were sitting in the shallow water at
+the edge of pond, where they were hidden by the grass. None was
+observed in open water, as is characteristic of calling males of _Bufo
+canaliferus_ and _marmoreus_.
+
+
+=Bufo marinus= Linnaeus
+
+     _Oaxaca_: Agua Caliente; Guichicovi (3); Mixtequilla;
+     Tolosita (6); Tehuantepec (37); Tuxtepec; Unión Hidalgo.
+     _Veracruz_: Ciudad Alemán (4); Cosamaloapan; Cuatotolapam
+     (19); 20 km. SE of Jesús Carranza (4); 38 km. SE of Jesús
+     Carranza (10); 20 km. NE of Jesús Carranza (4); Novillero.
+
+This large toad is abundant throughout the lowlands of the isthmus. The
+loud rattling call of males was heard on rainy nights throughout the
+summer. In March, 1956, several adults were found in a small cave back
+of a spring at Agua Caliente.
+
+
+=Bufo marmoreus= Wiegmann
+
+     _Oaxaca_: Cerro San Pedro (2); Chivela (5); Escurano (3);
+     Juchitán; Salina Cruz (101); Santa Lucía (2); 12 km. S of
+     Santiago Chivela (11); Santo Domingo; Tapanatepec;
+     Tehuantepec (100); Tequisistlán. _Veracruz_: Alvarado;
+     Coatzacoalcos.
+
+This toad is abundant on the Pacific lowlands, where it inhabits both
+open and dense scrub forest. On the Gulf lowlands its distribution
+seems to be limited to xeric coastal habitats. Aside from the specimens
+from Alvarado and Coatzacoalcos, it is known in Veracruz only from Boca
+del Río (Langebartel and Smith, 1959:27).
+
+The similarity in size of _Bufo marmoreus_ and _valliceps_ and their
+almost completely allopatric ranges suggest that the two species may be
+in competition at any one locality. Nevertheless, both were calling
+from a small rocky stream south of Santiago Chivela on July 6, 1956.
+
+On the night of July 6, 1958, an estimated 400 toads of this species
+made up a breeding congregation near Salina Cruz. The site was a
+shallow muddy pond about 20 × 40 meters located in an area cleared of
+scrub forest; the banks of the pond were devoid of vegetation (Pl. 5,
+fig. 2). Breeding in the same pond were _Rhinophrynus dorsalis_ and
+_Diaglena reticulata_. The following morning no more than a dozen
+_Bufo_ were found in the pond, but several individuals were found
+beneath debris and in small burrows near the pond. On July 7, 1958,
+large numbers of tadpoles and recently metamorphosed young were in a
+shallow grassy pool just east of Salina Cruz.
+
+Taylor (1943b:347) referred certain specimens from Tehuantepec to _Bufo
+perplexus_, a species closely related to _Bufo marmoreus_. Evidence to
+be presented elsewhere shows that _perplexus_ does not occur in the
+isthmus.
+
+
+=Bufo valliceps valliceps= Wiegmann
+
+     _Oaxaca_: Guichicovi (2); Matías Romero; 32 km. N of Matías
+     Romero (2); Nueva Raza; Río Sarabia (3); Santa María
+     Chimalapa (14); Santiago Chivela; 12 km. S of Santiago
+     Chivela (5); Santo Domingo (5); Tolosita (7). _Veracruz_:
+     Acayucan (3); Alvarado; Amatitlán; Ayentes; Cosamaloapan
+     (3); Cosoleacaque (6); Cuatotolapam (14); Hueyapan; 20 km.
+     ENE of Jesús Carranza (6); 20 km. S of Jesús Carranza; 25
+     km. SE of Jesús Carranza (23); 35 km. SE of Jesús Carranza;
+     60 km. SW of Jesús Carranza (5); La Oaxaqueña (4); Novillero
+     (4); San Lorenzo (5).
+
+Individuals were found in both wet and dry seasons. In the dry season
+they were most frequently found in rainforest, whereas in the rainy
+season breeding congregations were found in savannas as well. This toad
+occurs throughout the Gulf lowlands and on the Pacific slopes and in
+the Grijalva Valley of Chiapas and Guatemala, but not on the Pacific
+lowlands of the isthmus.
+
+I have not been able to recognize individuals referrable to the race
+_macrocristatus_. Firschein and Smith (1957:219) described
+_macrocristatus_ from the mountains of eastern Oaxaca and referred to
+it specimens from the Gulf lowlands of northern Chiapas. None of the
+present material shows the hypertrophied cranial crests supposedly
+characteristic of _macroaristatus_, nor do specimens from the isthmus
+resemble the population in the Grijalva Valley being described by L. C.
+Stuart, who will discuss the variation in, and the validity of, the
+named populations of _valliceps_.
+
+Five specimens from San Lorenzo, Veracruz (USNM 123516-20), were
+identified as _Bufo cristatus_ by Smith (1947:408). Firschein (1950:83)
+redefined the _cristatus_ group of _Bufo_ and assigned these specimens
+to _valliceps_.
+
+
+=Eleutherodactylus alfredi= Boulenger
+
+     _Oaxaca_: Tolosita (2). _Veracruz_: 35 km. SE of Jesús
+     Carranza (6).
+
+These specimens were collected in rainforest. Shreve (1957:247) pointed
+out the close resemblance between _E. alfredi_ and _E. conspicuus_ from
+Piedras Negras, Guatemala, and treated them as subspecies. Examination
+of the specimens from the isthmus, together with seven from central
+Veracruz and one from Teapa, Tabasco, suggests an even closer
+relationship. _Eleutherodactylus conspicuus_ was diagnosed by Taylor
+and Smith (1945:567) as differing from _alfredi_ "in lacking a tarsal
+fold, in having shorter hind legs with the tibiotarsal articulation
+reaching only to the nostril instead of beyond the tip of the snout;
+the vomerine teeth barely reach the posterior level of the choanae."
+The specimen from Teapa has the vomerine teeth reaching to the
+posterior edge of the choanae; in the eight specimens from the isthmus
+the teeth reach the posterior edge of the choanae in two and to the
+middle of the choanae in six; in seven specimens from central Veracruz
+the teeth reach the posterior edge of the choanae in two and to the
+middle in five. The tibiotarsal articulation extends beyond the tip of
+the snout in the specimen from Teapa and in two from central Veracruz;
+in three specimens from the isthmus and in one from central Veracruz it
+extends only to the nostril; in the others it extends to the snout. The
+tarsal fold is absent in the specimen from Teapa, in three from the
+isthmus, and in all those from central Veracruz; it is weakly present
+in the others.
+
+In the light of this evidence there seems to be little justification in
+recognizing two species or even two subspecies in this group.
+Consequently, _Eleutherodactylus conspicuus_ Taylor and Smith (1945) is
+here placed in the synonymy of _Eleutherodactylus alfredi_ Boulenger
+(1898), a species with a range extending from Cuautlapan and Potrero
+Viejo in central Veracruz southward and eastward in forested habitats
+to western El Petén, Guatemala.
+
+
+=Eleutherodactylus natator= Taylor
+
+     _Veracruz_: 35 km. SE of Jesús Carranza (3); 38 km. S of
+     Jesús Carranza; 55 km. SE of Jesús Carranza.
+
+The snout-vent length is 42.0 mm. in a male and averages 59.5 mm. in
+three adult females. The tarsal fold is low and extends about half the
+length of the tarsus; the first and second fingers are subequal in
+length; the tibiotarsal articulation extends beyond the tip of the
+snout. The patches of vomerine teeth lie between the posterior margins
+of the choanae. The throat and belly are immaculate, and the soles of
+the feet are dark. In the isthmus this species can be distinguished
+from _Eleutherodactylus rugulosus_ by less rugose skin on the dorsum
+and absence of dark ventral mottling.
+
+The specimens reported here extend the known range of _natator_
+eastward from Camotlán, Oaxaca; northward in Veracruz the species
+inhabits foothills as far north as Huatusco.
+
+
+=Eleutherodactylus rhodopis= Cope
+
+     _Oaxaca_: 30 km. N of Matías Romero; Río Sarabia (5);
+     Tapanatepec (87); Tolosita (6); between Zanatepec and
+     Tapanatepec. _Veracruz_: 25 km. SE of Jesús Carranza; 35 km.
+     SE of Jesús Carranza (2); 22 km. SSW of Jesús Carranza; 20
+     km. ENE of Jesús Carranza (7); Minatitlán; Tapalapan (5).
+
+For the purposes of the present study I am not recognizing
+_Eleutherodactylus beati_, _E. dorsoconcolor_, and _E. venustus_ as
+specifically, or even subspecifically distinct from the earlier named
+_E. rhodopis_. Probably these are mere color varieties of a single
+species.
+
+In the dry season frogs of this species were in humid forests, where
+they were most frequently found along small streams and in ravines. The
+species is widespread in the Gulf lowlands, but does not occur on the
+Plains of Tehuantepec. It does inhabit the Pacific slopes on the
+foothills of the Sierra Madre de Chiapas, the western part of which
+extends into eastern Oaxaca near Tapanatepec.
+
+
+=Eleutherodactylus rugulosus= Cope
+
+     _Oaxaca_: La Princesa (30); Modelo; Santa Lucía (10);
+     Tapanatepec (26); Tehuantepec (6); Tres Cruces (8).
+     _Veracruz_: Tapalapan (5).
+
+In addition to the specimens from the lowlands of the isthmus, for the
+purposes of the following discussion, I have included data on two
+specimens from the southern slopes of the Sierra del Sur in Oaxaca
+(Mirador and Chacalapa) and on several specimens from Los Tuxtlas in
+Veracruz (Los Chaneques, 67; Salto de Eyipantla, 35; and San Andrés
+Tuxtla, 11).
+
+Frogs of the _Eleutherodactylus rugulosus_ complex occur from southern
+Veracruz and Sinaloa southward through Central America. Taylor
+(1940:401) described _E. vocalis_ from Hacienda El Sabino, Michoacán;
+Taylor and Smith (1945:580) described _E. avocalis_ from Tres Cruces,
+Oaxaca. These have been considered as species distinct from
+_rugulosus_, which is known to occur in Veracruz, Guerrero, and Chiapas
+southward into Central America. Although the large number of specimens
+collected in the isthmus does not aid in defining the ranges of the
+taxa involved, these specimens do give some idea of the variation in
+certain characters in a given population.
+
+In specimens from Los Tuxtlas the tarsal fold is well-developed and
+extends two-thirds to three-fourths the length of the tarsus; the
+tibiotarsal articulation reaches the nostril and sometimes slightly
+beyond the tip of the snout. In males the tympanum is nearly equal to
+the diameter of the eye; in females it is about one-half the diameter
+of the eye. The posterior surfaces of the thighs are dark brown or
+black with whitish or cream-colored spots, flecks, or irregular
+mottling. The tarsal fold is dark; the throat is pale in some
+individuals, but in most is mottled with dark brown or gray flecks.
+Individuals from La Princesa near the continental divide in Oaxaca show
+the same variation in body proportions and development of the tarsal
+fold. The posterior surfaces of the thighs are dark brown indistinctly
+mottled with lighter brown. The throat is dark brown. Specimens from
+the Pacific slopes of Oaxaca, including the Plains of Tehuantepec, have
+dark brown thighs mottled with dusty cream. The tibiotarsal
+articulation extends slightly beyond the tip of the snout in all
+specimens. In males the tympanum is equal to about two-thirds the
+diameter of the eye. Duellman (1958b:6) discussed the variation in
+these characters in populations in Colima, Jalisco, and Michoacán.
+
+Until the extent of variation of these characters is known throughout
+the range of _rugulosus_, the recognition of populations either as
+species or subspecies seems superfluous. Consequently, I have used the
+oldest name; this does not necessarily imply, however, that all
+populations of _rugulosus_ (_sensu lato_) are conspecific.
+
+Of the 200 specimens examined, 15 have a middorsal stripe that is red
+or yellow. The iris varies from a copper to a dark golden color and
+shines bright red at night. Many of the specimens are juveniles; these
+were collected in the dry season, at which time they were found beneath
+rocks along streams, in road culverts where there was some water, and
+in holes in banks and cliffs.
+
+
+=Microbatrachylus pygmaeus= Taylor
+
+     _Oaxaca_: La Princesa (5); Matías Romero (9); Río Sarabia
+     (41); Tolosita (2). _Veracruz_: Jesús Carranza; 20 km. ENE
+     of Jesús Carranza.
+
+The specimens listed above vary widely in color patterns; some of the
+patterns are characteristic of certain named "species": _albolabris_,
+_imitator_, _lineatissimus_, and _minimus_. The large series from the
+Río Sarabia contains all of the color patterns; this series was
+obtained in one small ravine in the rainforest. At least in the
+isthmian region, this species does not inhabit the Pacific slopes and
+lowlands.
+
+
+=Syrrhophus leprus= Cope
+
+     _Oaxaca_: 33 km. N of Matías Romero; Santa Efigenia.
+     _Veracruz_: San Lorenzo.
+
+Although the type locality is stated to be Santa Efigenia on the
+Pacific slopes of the Sierra Madre de Chiapas in eastern Oaxaca, the
+type specimen probably came from the northern slopes of the mountains.
+All other known specimens are from the Gulf slopes and lowlands, and
+from several localities in Los Tuxtlas. Details concerning specimens
+from the isthmus and other parts of the range were given by Duellman
+(1958c:8).
+
+Smith (1947:408) reported a specimen of _Syrrhophus verruculatus_
+Peters from San Lorenzo, Veracruz; he stated that this specimen (USNM
+123530) could not be _S. leprus_, because it had a gray belly, nor _S.
+cystignathoides_, because of the dark and light dorsal coloration.
+Firschein (1954:57) in his review of the species of _Syrrhophus_ in
+eastern México referred the specimen to _S. cystignathoides_. The
+specimen is in poor condition. Nevertheless, specific determination is
+possible. Numerous specimens of _S. leprus_ from Los Tuxtlas have gray
+bellies; some have heavier pigmentation than the specimen from San
+Lorenzo. In preservative the dorsum is dark brown with lighter
+mottling. There is little doubt that the specimen from San Lorenzo is
+a _Syrrhophus leprus_, an abundant and widespread species in the
+humid Gulf lowlands of southern México, and not _verruculatus_, if
+this is a valid species (see Firschein, _op. cit._:58), and not
+_cystignathoides_, a species known from San Luis Potosí southward to
+central Veracruz.
+
+
+=Syrrhophus pipilans pipilans= Taylor
+
+     _Oaxaca_: Cerro Arenal; Cerro San Pedro; 6 km. N of Chivela;
+     14 km. W of Tehuantepec (2).
+
+In the isthmian region this frog is known only from the Pacific slopes
+and the Plains of Tehuantepec. Males call from the ground and from
+trees to heights of about four meters. The call is a single, high, long
+"peep."
+
+
+=Engystomops pustulosus= Cope
+
+     _Oaxaca_: Chivela; La Ventosa (3); Santo Domingo;
+     Tapanatepec (14); Tehuantepec (61); Unión Hidalgo (62).
+     _Veracruz_: Acayucan; Cuatotolapam (7); 10 km. SE of
+     Hueyapan (11).
+
+Large congregations were breeding at Tehuantepec on July 5, at
+Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs
+were breeding in open ponds in scrub forest and savanna; none was found
+in the rainforest. Males call while floating on the water (Pl. 7, fig.
+1); the call is a soft "do-ing, do-ing" with a rising tone on the last
+note. Numerous individual egg masses were along the bank of a pond near
+Tehuantepec; one large composite egg mass there had a surface area of
+about one square meter (Pl. 7, fig. 2). The large series from Unión
+Hidalgo was obtained by digging specimens out of a dry sandy river bank
+in the dry season. Some of the individuals were buried to a depth of 25
+centimeters.
+
+In life individuals from the Pacific lowlands were dull brown and gray;
+those from Acayucan were dark chocolate brown to black with pink or red
+blotches, forearms, and dorsal stripe. Not all specimens from the
+Atlantic lowlands are so colored; individuals from Cordoba and
+Mirador, Veracruz, are like those from Tehuantepec.
+
+
+=Leptodactylus labialis= Cope
+
+     _Oaxaca_: Agua Caliente; Chivela (2); Matías Romero (12); 33
+     km. N of Matías Romero (4); Mixtequilla; Santa Efigenia;
+     Tapanatepec; Tehuantepec (38); Tolosita (2); 33 km. W of
+     Zanatepec (49). _Veracruz_: Acayucan (3); Ciudad Alemán;
+     Cuatotolapam (10); Hueyapan; La Oaxaqueña (4); 38 km. SE of
+     Jesús Carranza; 20 km. ENE of Jesús Carranza; Novillero (3);
+     San Lorenzo (2).
+
+Although _Leptodactylus labialis_ does not appear to be so abundant as
+_Leptodactylus melanonotus_, the former was found throughout the
+lowlands of the isthmus. In the dry season individuals were found along
+streams, and in the rainy season breeding congregations were found in
+rain pools, marshes, ponds, and even small puddles. The call is a slow
+"wort, wort, wort." Males call beneath the water and from beneath rocks
+and from holes in the ground. The average snout-vent length of eight
+adult males is 37.2 mm. A completely metamorphosed juvenile obtained at
+Hueyapan on July 24, 1956, has a snout-vent length of 11 mm.
+
+
+=Leptodactylus melanonotus= Hallowell
+
+     _Oaxaca_: Agua Caliente (25); Cerro Arenal (2); Cerro
+     Quiengola (3); Cerro San Pedro (3); Chivela (2); Coyol;
+     Juchitán; Matías Romero (11); Mixtequilla (2); Papaloapan
+     (2); Salazar (9); Salina Cruz; 11 km. S of Santiago Chivela;
+     Tapanatepec (17); Tehuantepec (176); Tolosita; Unión
+     Hidalgo; 27 km. W of Zanatepec (6). _Veracruz_: Acayucan;
+     Cuatotolapam (9); Cosoleacaque; 20 km. ENE of Jesús Carranza
+     (2); 20 km. SE of Minatitlán (2); Novillero; San Lorenzo
+     (6).
+
+This frog is abundant throughout the lowlands of the isthmus, where in
+the dry season individuals were found along streams and beneath rocks
+at a spring seepage. In the rainy season males were calling from nearly
+every bit of standing water. The call is a soft clicking sound
+resembling that made by striking two small stones together. The average
+snout-vent length of ten adult males is 41.8 mm. There is considerable
+variation in the extent of the yellowish brown glandular areas on the
+belly. Some have none, whereas others have a broad area on the chest, a
+band along the flanks, and a thin band across the lower abdomen.
+Individuals collected in the dry season vary in the same fashion as do
+those collected in the rainy season, at which time they were breeding.
+The glands are equally well-developed in adults of both sexes, and were
+present in some juveniles with snout-vent lengths of less than 20 mm.
+Apparently the development of the glands is not associated with
+maturity, sex, or size.
+
+
+=Diaglena reticulata= Taylor
+
+     _Oaxaca_: Cerro Arenal; Chivela; Salina Cruz (26); San
+     Antonio (3); Tehuantepec (2); 8.6 km. W of Tehuantepec (11);
+     Zarzamora.
+
+Breeding congregations of this rare frog were found 8.6 kilometers west
+of Tehuantepec on July 5, 1956, and at Salina Cruz on July 6, 1958.
+Both choruses took place immediately after torrential rains. In both
+instances the frogs were in and about open muddy pools in the scrub
+forest (Pl. 5, fig. 2); males called from the bank near the water, and
+clasping pairs were found only on land (Pl. 8, figs. 1-2). The call is
+a loud, nasal "braaa," two to three seconds in duration. Amplexus is
+axillary.
+
+The dorsal ground color is light yellowish green tending towards olive
+on the head and fading to yellow on the flanks. The ventral surfaces,
+including the vocal sac, are white; the iris is golden and flecked with
+black. The present series agrees well with the description of
+_reticulata_ (based on two specimens) given by Taylor (1942:60). A
+detailed analysis of variation, comparison with related species, and
+descriptions of tadpoles are reserved for a future report.
+
+
+=Hyla baudini= Duméril and Bibron
+
+     _Oaxaca_: Bisilana; Cerro Quiengola (2); Cerro San Pedro;
+     Coyol; Matías Romero (12); Mixtequilla; Río Sarabia (7);
+     Salazar; San Antonio; 11 km. S of Santiago Chivela; Santo
+     Domingo (3); Tapanatepec (2); Tehuantepec (23); Tolosita.
+     _Veracruz_: Acayucan; Amatitlán; Ciudad Alemán (3);
+     Cosamaloapan (2); Cuatotolapam (15); 10 km. SE of Hueyapan;
+     20 km. S of Jesús Carranza; 38 km. S of Jesús Carranza (2);
+     20 km. ENE of Jesús Carranza (4); La Oaxaqueña (2);
+     Minatitlán (2); Naranja (3); Novillero (9); Río de las
+     Playas (2); San Lorenzo (5); Tapalapan (2).
+
+Commonly found on both sides of the isthmus, this large tree frog
+nearly always is associated with trees; it is not found in the
+savannas, although it breeds in savannas adjacent to rainforest. It
+appears to be somewhat more abundant in scrub forest than in
+rainforest. In the daytime individuals were found under the outer
+sheaths of banana plants, in the axils of leaves of elephant ears
+(_Xanthosoma_), in cavities in trees, and on shaded limbs in the
+forest. Recently metamorphosed individuals having snout-vent lengths
+slightly more than 20 mm. were found in the latter part of July.
+
+
+=Hyla ebraccata= Cope
+
+     _Oaxaca_: Donají (17); 43 km. N of Matías Romero (27);
+     Sarabia (6); Tolosita (3); Ubero (17). _Veracruz_: Aquilera.
+
+This small species was found only in forested areas, where calling
+males were on bushes and trees around rain pools. The call is a harsh
+squawk repeated at intervals of 15 to 20 seconds, followed by a minute
+or more of silence, and then repeated. Clasping pairs were found on
+bushes and in the water.
+
+The dorsum bears a dark chocolate brown hour glass-shaped mark, which
+in some individuals is broken into a large mark posteriorly and a
+smaller triangular one on the head and nape. The dorsal ground color
+varies from pale cream or ivory to yellow or tan. The intensity of the
+dorsal pigmentation is subject to rather rapid change. The flanks,
+hands, and anterior part of the venter are lemon yellow; the feet,
+thighs, and posterior part of the venter are golden yellow. The dorsal
+surface of the shank is yellow to tan with chocolate brown bars or
+spots; the heel is pale yellow. There is a dark brown bar in the loreal
+region and a dark brown bar extending posteriorly from the eye to a
+point above the insertion of the forelimb. The iris is a copper color.
+The toes are completely webbed; the fingers, one-third webbed. There is
+a small axillary web that is evident when the forelimbs are at right
+angles to the body. Twenty males have an average snout-vent length of
+28.1 mm.; three females, 35.3 mm. There are no nuptial tuberosities on
+the pollex of breeding males.
+
+This species has been collected at Coyame and Catemaco in Los Tuxtlas
+and at various localities in Tabasco; it apparently ranges eastward
+from southern Veracruz, México, in humid forests to El Petén,
+Guatemala.
+
+
+=Hyla loquax= Gaige and Stuart
+
+     _Oaxaca_: Donají (7); 43 km. N of Matías Romero (21).
+     _Veracruz_: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW
+     of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San
+     Lorenzo (8).
+
+In the isthmus this species is known only from the humid forests of the
+Gulf lowlands; it is also known from Boca del Río, Veracruz, and from
+Teapa and Villa Hermosa, Tabasco.
+
+Calling males were found on aquatic plants above the water in deep
+ponds in the forest where it was necessary for the collector to wade
+waist-deep in water to obtain them. The call is a loud "hah-onk."
+Individuals, when active at night, are yellowish tan above with light
+olive green spots. The flanks, belly, and vocal sac are yellow, and the
+anterior and posterior surfaces of the thighs and webbing of the feet
+are bright orange-red or tomato red. Individuals found during the day
+are grayish brown with olive markings or reddish brown with black
+markings. Sleeping individuals are ivory-gray with faint gray markings.
+The iris is a bright copper color. Fifteen adult males have an average
+snout-vent length of 41.7 mm.; they have no horny nuptial pads on the
+pollex.
+
+The relationships of this species are with _Hyla rickardsi_ Taylor, a
+species known only from the foothills of the Sierra Madre Oriental in
+the states of Puebla and Veracruz. The distinguishing characteristics
+of these species are given in Table 1. Living individuals may be
+distinguished immediately by the flash colors on the thighs--red in
+_loquax_ and yellow in _rickardsi_. The calls of the two species are
+distinctly different; that of _rickardsi_ is a high-pitched, loud
+rattle continued for several seconds, notably different from the
+goose-like honk of _loquax_.
+
+TABLE 1.--COMPARISON OF CERTAIN CHARACTERS IN HYLA LOQUAX
+AND HYLA RICKARDSI
+
+=================================+================+====================
+          CHARACTER              |   _loquax_     |    _rickardsi_
+---------------------------------+----------------+--------------------
+Toe webbing                      | Full           | Three-fourths
+                                 |                |
+Finger webbing                   | Three-fourths  | One-half
+                                 |                |
+Average snout-vent length (Male) | 41.7 mm.       | 37.4 mm.
+                                 |                |
+Tympanum/eye (Male)              | 63.2%          | 55.8%
+                                 |                |
+Dorsal leg pattern               | Barred         | Unmarked
+                                 |                |
+Tarsal fold                      | Tubercular     | Absent
+                                 |                |
+Tarsal stripe                    | Absent or      | Broad, indistinct,
+                                 |   indistinct   |   or absent
+                                 |                |
+Dorsolateral stripe              | Absent         | Present
+                                 |                |
+Light line over anus             | Broad          | Narrow
+                                 |                |
+Flash colors                     | Red            | Yellow
+                                 |                |
+Iris color                       | Copper         | Bronze
+---------------------------------+----------------+--------------------
+
+The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were
+identified as _Hyla rickardsi_ by Smith (1947:409). The flash colors
+have faded in preservative, and so are of no aid in identifying these
+specimens. Two are adult females with snout-vent lengths of 35 and 39
+mm. In possessing a relatively large tympanum and barred thighs, and in
+lacking a dorsolateral stripe they are typical of _loquax_, but in the
+amount of webbing on the hands and feet, broad tarsal stripe, and
+narrow anal stripe they are like _rickardsi_. The third specimen, a
+juvenile, has a snout-vent length of 25 mm. In coloration it resembles
+the adults; it has more distinct bars on the limbs. On the basis of
+geography these specimens should be _loquax_, for the closest known
+record of _rickardsi_ is more than 200 kilometers to the northwest,
+whereas _loquax_ is known from several localities around San Lorenzo.
+
+Shannon and Werler (1955:383) described _Hyla axillamembrana_ from the
+lower southern slopes of Los Tuxtlas. The unique type is a small male
+(27 mm. snout-vent). I have examined the type and find no great
+differences between it and small specimens of _loquax_. It is not
+possible to determine the color of the thighs, nor was this information
+given in the description. _Hyla axillamembrana_ is here considered to
+be a synonym of _Hyla loquax_.
+
+
+=Hyla microcephala martini= Smith
+
+     _Oaxaca_: Donají (15); 43 km. N of Matías Romero (19); Río
+     Sarabia (2); Sarabia (11); Tolosita. _Veracruz_: Acayucan
+     (17); Alvarado (41); Aquilera (21); 8 km. SW of
+     Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of
+     Hueyapan; Naranja (3); Novillero.
+
+This frog is abundant in the Gulf lowlands of the isthmus, where large
+breeding congregations were found in grassy ponds on the savannas and
+in openings in the forest. Most frequently males were calling from
+grasses and reeds in the ponds; many individuals were perched
+precariously on thin blades as high as one meter above the water. The
+call is a series of low squeaks.
+
+Individuals found at night were pale yellow above with light brown
+lines arranged in an irregular pattern on the back, but often forming a
+cross or an X-shaped mark in the scapular region. There is a brown
+stripe from the nostril to the eye and thence to the groin. Anteriorly
+this stripe is bordered above by a thin white or cream-colored line.
+Numerous small brown flecks are scattered on the back and dorsal
+surface of the shank. In most specimens there are thin transverse brown
+bars on the shank. The thighs and undersides of the limbs are golden
+yellow; the belly and vocal sac are lemon yellow. The iris is yellowish
+brown. During the day individuals assume a pale reddish tan ground
+color with darker brown markings. Twenty-five adult males from Alvarado
+have an average snout-vent length of 24.1 mm.
+
+
+=Hyla picta= Günther
+
+     _Oaxaca_: Donají (8); Sarabia (11); Tolosita (15); Ubero
+     (6). _Veracruz_: 19 km. N of Acayucan (4); Alvarado (5);
+     Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan
+     (7); Lerdo de Tejada; Tula (3).
+
+Widespread in the forests, scrub, and savannas on the Gulf lowlands of
+the isthmus, these frogs were found breeding at numerous localities.
+Males call from grasses and bushes growing in and about ponds. The
+call is a high-pitched insect-like trill. At night these frogs are pale
+yellow above; they change to light grayish tan during the day. A dark
+stripe extends from the nostril to the eye and thence posteriorly to a
+point between the axilla and groin. Above this dark stripe is a broader
+white stripe. Scattered on the dorsum are brown flecks or spots; the
+shanks are marked with poorly-defined cross-bars. The thighs are deep
+yellow below and paler above with scattered dark flecks. The belly is
+white, and the vocal sac is yellow. The iris is golden. Twenty males
+have an average snout-vent length of 21.5 mm.; three females, 24.0 mm.
+
+
+=Hyla robertmertensi= Taylor
+
+     _Oaxaca_: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38);
+     7.2 km. WNW of Zanatepec (77).
+
+This species was found in the isthmian region only on the Pacific
+lowlands at the southern base of the western part of the Sierra Madre
+de Chiapas. On July 13, 1956, many large choruses were discovered. The
+calling males were on reeds and thorn scrub in and at the edge of
+temporary ponds; the call is a cricket-like "creak-creack," quickly
+followed by a series of notes "creak-eek-eek-eek-eek."
+
+At night the dorsal ground color is pale yellow; this changes to
+pinkish buff during the day. There is a grayish or brown dark stripe
+from the nostril to the eye; the stripe continues to the groin. This
+dark stripe is bordered above by a narrow white stripe. The belly is
+white, and the vocal sac is yellow. The iris is dull reddish brown.
+Twenty-five males have an average snout-vent length of 24.7 mm.
+
+
+=Hyla staufferi= Cope
+
+     _Oaxaca_: Chivela; Huilotepec (5); Juchitán (4); Matías
+     Romero (4); 25 km. N of Matías Romero; Mixtequilla (4); Río
+     Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3);
+     Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero;
+     Unión Hidalgo; Zanatepec (6). _Veracruz_: Acayucan (7);
+     Alvarado (3); Amatitlán; Aquilera; Ciudad Alemán (3); 8 km.
+     SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8);
+     10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula
+     (2).
+
+This is the only species of small hylid that crosses the isthmus.
+Calling males were found in and about ponds on the savannas in southern
+Veracruz, in ponds in open forest in northern Oaxaca (not in forest
+pools), and in temporary pools in the scrub forest on the Pacific
+lowlands. Individuals usually called from bushes and reeds in or at the
+edge of ponds. The call is a short "braaa." Dates of breeding choruses
+indicate that by the time the other small species of hylids in the Gulf
+lowlands reach the peak of their breeding season, that of _H.
+staufferi_ is essentially over; no large breeding congregations were
+found in July. On July 8, 1956, two metamorphosing young were found
+clinging to blades of grass in a pond; they had snout-vent lengths of 8
+and 9 mm. and tail stumps less than 3 mm. in length. Others were found
+on July 13 and 26. The juveniles are nearly unicolor olive green above
+and white below.
+
+In life the adults vary greatly in color pattern. The dorsal ground
+color is yellowish tan to olive brown with olive brown or dark brown
+spots, some of which in certain individuals are connected to form
+longitudinal dark stripes. On the posterior surface of the thighs are
+small white flecks. The belly is white, and the vocal sac is a rich
+yellow. Twenty males have an average snout-vent length of 26.3 mm.;
+they have no horny nuptial pads. No noticeable differences in either
+color or body proportions were found between the populations on either
+side of the isthmus.
+
+
+=Hylella sumichrasti= Brocchi
+
+     _Oaxaca_: Cerro Arenal (5); Cerro San Pedro (2); Escurano;
+     La Concepción (41); Portillo Los Nanches (6); San Antonio
+     (16); 11 km. S of Santiago Chivela (18); Santa Lucía (7);
+     Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces
+     (19).
+
+With the exception of the series from 11 kilometers south of Santiago
+Chivela, most of these specimens were found in small arboreal
+bromeliads during the dry season. Males were found along a clear,
+shallow, rocky stream south of Santiago Chivela on July 6, 1956. The
+frogs were calling from bushes and rocks in and along the stream. When
+disturbed, they jumped into the water and floated downstream until they
+were able to hold onto a rock or other object. The call is a loud
+"bra-a-ah." In breeding individuals the dorsum is pale yellow; the
+belly is white, and the vocal sac is yellow. The iris is pale golden
+yellow. Eighteen males have an average snout-vent length of 25.2 mm.
+All have dark brown nuptial tuberosities on the pollex.
+
+Certain diagnostic characters of this species as given by Taylor
+(1943a:50) and Taylor and Smith (1945:598) are in need of revision.
+_Hylella sumichrasti_ has been characterized as having no vocal sac,
+rarely having vomerine teeth, and as having a relatively smooth throat.
+The vocal sac in breeding males is quite evident; it is single, median,
+and when expanded, spherical. The openings into the vocal sac are
+narrow slits along the inner posterior border of the jaw rami. Of 151
+specimens studied, 74 have vomerine ridges between the choanae, and 36
+of these have one to three teeth on each ridge. The belly and
+undersurfaces of the thighs are granular; the throat is only somewhat
+less so. The granular condition may be correlated with breeding, for
+specimens obtained from bromeliads in the dry season had rather smooth
+throats. It seems that the vocal sac atrophys in the non-breeding
+season. These seasonal changes may account for the diagnoses given by
+Taylor (_op. cit._) and Taylor and Smith (_op. cit._); likewise, since
+many of the specimens obtained by Smith in the dry season were
+juveniles and subadults, the development of the vomerine ridges could
+not be diagnosed properly.
+
+The range of this species encompasses the Pacific slopes of the Isthmus
+of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of
+Tonalá in western Chiapas. Priscilla Starrett collected tadpoles of _H.
+sumichrasti_ from a stream 19 km. N of Arriaga, Chiapas. These limited
+observations on the ecology of this frog suggest that it breeds in the
+fast-moving streams of the Pacific slopes, and that it seeks shelter in
+arboreal bromeliads during the dry season.
+
+
+=Phrynohyas modesta= Taylor and Smith
+
+     _Oaxaca_: Tuxtepec. _Veracruz_: 20 km. S of Jesús Carranza;
+     20 km. ENE of Jesús Carranza (2); Minatitlán.
+
+I have not collected this species in the isthmus. The locality records
+indicate that the range is discontinuous (Duellman, 1956:27). The
+species occurs on the humid Pacific slopes from south-central Chiapas
+eastward to El Salvador and on the humid Gulf lowlands from southern
+Veracruz eastward into Tabasco, but is unknown from the dry Pacific
+slopes and plains in the isthmus.
+
+The acquisition of several specimens of this species in southern
+Veracruz, Tabasco, and Oaxaca, together with a knowledge of the
+variation displayed by _Phrynohyas spilomma_, suggests that _modesta_
+may be a color variety of _spilomma_.
+
+
+=Phrynohyas spilomma= Cope
+
+     _Oaxaca_: Tapanatepec (3). _Veracruz_: Amatitlán (12);
+     Chacaltianguis (2); Ciudad Alemán (6); Cosamaloapan;
+     Novillero (3).
+
+Like the preceding species, this frog is unknown from the arid Pacific
+lowlands of the isthmus; its presence at Tapanatepec, a locality
+situated in more mesic conditions than prevail on the Plains of
+Tehuantepec, indicates that it may have a distribution on the Pacific
+slopes much like that of _P. modesta_. Furthermore, this frog was not
+detected in the rainforests of the Gulf lowlands; in that region it was
+found only in scrub forest and savanna.
+
+On July 26, 1956, numerous choruses of these frogs were heard between
+Ciudad Alemán and Tlacotalpan, Veracruz. The call is a loud, nasal
+"grawl" repeated continuously. The males call from the water. Several
+clasping pairs were found in shallow grassy ponds amidst the scrub
+forest. The ground color varies from reddish brown to tan with dark
+brown dorsal markings. The iris is golden, and the vocal sacs are dark
+olive brown. After a light shower during the dry season, six
+individuals were found on the low branches of trees at night near
+Ciudad Alemán.
+
+
+=Phyllomedusa callidryas taylori= Funkhouser
+
+     _Oaxaca_: Donají (9); Sarabia (8); Tolosita (6); Ubero (27).
+     _Veracruz_: Alvarado (7); Aquilera; Berta; Coatzacoalcos
+     (9); 10 km. SE of Hueyapan (5); Naranja (17).
+
+In life this frog presents a striking array of colors. The dorsum
+varies from pale green to dark olive green; there may be scattered
+whitish or cream-colored spots on the back. On the flanks are bright
+yellow to deep cream-colored vertical bars separated by pale blue or
+purple interspaces. The thighs and undersurfaces of the hind limbs are
+golden orange; the belly is yellow, and the throat is cream-colored.
+The iris is crimson; the transparent part of the lower eyelid has
+golden reticulations. When the frog is resting, the forefeet are folded
+beneath the throat, and the limbs are folded tightly against the body.
+In this position and with the eyes closed and head flattened, this
+gaudy frog assumes the appearance of a small elliptical green leaf.
+
+Throughout the month of July, 1956, _Phyllomedusa_ was breeding in
+ponds in or adjacent to the rainforest in northern Oaxaca and in
+southern Veracruz. Only at Alvarado was it found breeding in a grassy
+pond. Males and females alike were found on bushes and trees in and
+around the ponds. The call is a single "wank." Amplexing males continue
+to call, but the call is softer and less nasal in quality. The eggs are
+encased in pale green gelatin and attached to leaves on branches
+overhanging the water. Three egg clutches contained 38, 41, and 46
+eggs.
+
+
+=Phyllomedusa dacnicolor= Cope
+
+     _Oaxaca_: Escurano; Tehuantepec.
+
+Although it is abundant on the Pacific lowlands to the northwest in
+Guerrero, Michoacán, and Colima, this species is known only from two
+specimens from Tehuantepec. There is no apparent physical barrier to
+their distribution in the isthmus; in the Balsas Basin the species
+lives in a hotter, more arid environment than that at Tehuantepec.
+
+
+=Gastrophryne usta= Cope
+
+     _Oaxaca_: Santa Efigenia; Tehuantepec (10); 24 km. W of
+     Tehuantepec; Tolosita (2). _Veracruz_: Ayentes (6); La
+     Oaxaqueña; Novillero (2); San Lorenzo.
+
+Calling males were found in open scrub forest near Tehuantepec and in
+savannas near Novillero. The specimens from Tolosita were found under
+cover in a clearing in the forest (Fugler and Webb, 1957:106).
+
+Specimens from the Pacific lowlands are typical of _Gastrophryne usta
+gadowi_ Boulenger in possessing a thin line on the posterior surface of
+the thighs and a thin line from the snout to the vent. Of nine
+specimens from the Gulf lowlands (Ayentes, Novillero, and San Lorenzo),
+seven have a middorsal line; this is narrow in four and wide in three.
+Five have the stripes on the thighs. Two specimens from the middle of
+the isthmus (Tolosita) have no stripes on the thighs; one has a thin
+middorsal line, and the other has a broad line. The adult males have a
+black throat; females have a mottled one. The brown reticulations on
+the bellies of specimens from the Gulf lowlands is bolder than on
+specimens from the Pacific lowlands. The presence of certain characters
+supposedly diagnostic of the subspecies _gadowi_ (line on dorsum and
+thighs) in the population of _usta_ in southern Veracruz suggests that
+a redefinition of the ranges of these subspecies will be in order when
+sufficient material is available to delimit them accurately. For the
+present I prefer to consider all specimens from the isthmus solely as
+_Gastrophryne usta_ without referring them to subspecies.
+
+
+=Rana palmipes= Spix
+
+     _Oaxaca_: Matías Romero (11); 11 km. S of Santiago Chivela;
+     Santo Domingo; Sarabia. _Veracruz_: Coatzacoalcos;
+     Cuatotolapam; 25 km. SE of Jesús Carranza (4); Tlacotalpan
+     (2); Tula.
+
+Adults were found along streams and in marshes in savannas and
+rainforest. These frogs are wary and difficult to capture, even at
+night. _Rana palmipes_ is another species that has a discontinuous
+distribution in the isthmus. The species does not occur on the Pacific
+lowlands of the isthmus, but does occur on the more humid Pacific
+slopes of Chiapas and Guatemala.
+
+Tadpoles were found in a small sluggish tributary to the Río Sarabia.
+
+
+=Rana pipiens= Schreber
+
+     _Oaxaca_: Agua Caliente; Cerro Quiengola; Escurano (14); Río
+     Sarabia (2); Tapanatepec (5); Tehuantepec (24). _Veracruz_:
+     Acayucan; Cuatotolapam (15); Jesús Carranza (2); 20 km. S of
+     Jesús Carranza (11); 25 km. SE of Jesús Carranza; 20 km. ENE
+     of Jesús Carranza (10); San Lorenzo (10).
+
+As in most other places in México and northern Central America, this
+species occurs wherever there is permanent water. Males were heard
+calling from woodland ponds and from savanna ponds.
+
+
+
+
+SUMMARY
+
+
+Investigations of the amphibians and their environments in the Isthmus
+of Tehuantepec have been presented with the aim of gaining an
+understanding of the present biological and of the historical events
+responsible for the present patterns of distribution of amphibians in
+this region.
+
+The Isthmus of Tehuantepec embraces three major environments--savanna,
+semi-arid scrub forest, and quasi-rainforest. The rainforest presents
+an environment noticeably different from the other two and has a
+different amphibian fauna.
+
+Analysis of present patterns of distribution shows that certain species
+are restricted to the rainforests on the Gulf lowlands; others live
+only in the semi-arid scrub forests on the Pacific lowlands. A third
+group of species lives on both the Gulf and Pacific lowlands; most of
+these species occur only in the scrub forests or savannas on the Gulf
+lowlands, but some also inhabit the rainforest. In one way or another
+the isthmus presents a barrier to the distribution of 75 per cent of
+the species of amphibians living in the lowlands; it is a greater
+barrier still to the species inhabiting the highlands on either side.
+
+Present patterns of distribution are attributed to bioclimatic
+fluctuation in the Pleistocene. In the course of these climatic shifts,
+tropical environments and their amphibian inhabitants seem to have
+survived in the isthmian region.
+
+The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 16 genera and 36 species. Systematic studies of all
+available specimens from the region show that _Eleutherodactylus
+conspicuus_ Taylor and Smith is a synonym of _Eleutherodactylus
+alfredi_ Boulenger and that _Hyla axillamembrana_ Shannon and Werler is
+a synonym of _Hyla loquax_ Gaige and Stuart.
+
+
+
+
+LITERATURE CITED
+
+
+BEARD, J. S.
+
+     1953. The savanna vegetation of northern tropical America.
+     Ecol. Mono., vol. 23 (2):149-215.
+
+BOULENGER, G. A.
+
+     1898. Fourth report on additions to the batrachian
+     collection in the Natural History Museum. Proc. Zool. Soc.
+     London, 1898, pp. 473-482, pls. 38-39.
+
+BURT, C. E.
+
+     1931. A study of the teiid lizards of the genus
+     _Cnemidophorus_ with special reference to their phylogenetic
+     relationships. Bull. U. S. Nat. Mus., No. 154, pp. viii +
+     286.
+
+CONTRERAS A., A.
+
+     1942. Mapa de las provincias climatologias de la Republica
+     Mexicana. México, D. F., Dirección de Geografía, Meterología
+     e Hidrología, pp. i-xxviii, tables 1-54, 2 maps.
+
+COOKE, C. W.
+
+     1945. Geology of Florida. Florida Geol. Surv., Geol. Bull.,
+     No. 29:1-339.
+
+DORF, E.
+
+     1959. Climatic changes of the past and present. Contrib.
+     Mus. Paleo. Univ. Michigan, vol. 13 (8):181-210.
+
+DUELLMAN, W. E.
+
+     1956. The frogs of the hylid genus _Phrynohyas_ Fitzinger,
+     1843. Miscl. Publ. Mus. Zool. Univ. Michigan, No. 96:1-47,
+     pls. 1-6.
+
+     1958a. A monographic study of the colubrid snake genus
+     _Leptodeira_. Bull. Amer. Mus. Nat. Hist., vol. 114:1-152,
+     pls. 1-31.
+
+     1958b. A preliminary analysis of the herpetofauna of Colima,
+     Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+     589:1-22.
+
+     1958c. A review of the frogs of the genus _Syrrhophus_ in
+     western Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+     594:1-15, pls. 1-3.
+
+DUELLMAN, W. E., and SCHWARTZ, A.
+
+     1958. Amphibians and reptiles of southern Florida. Bull.
+     Florida State Mus., vol. 3 (5):181-324.
+
+DUNN, E. R.
+
+     1942. The American caecilians. Bull. Mus. Comp. Zool., vol.
+     91 (6):439-540.
+
+DURHAM, J. W., ARELLANO, A. R. V., and PECK, JR., J. H.
+
+     1952. No Cenozoic Tehuantepec seaways. Bull. Geol. Soc.
+     Amer., vol. 63:1245.
+
+FIRSCHEIN, I. L.
+
+     1950. A new toad from Mexico with a redefinition of the
+     _cristatus_ group. Copeia, 1950 (2):81-87, pl. 1.
+
+     1954. Definition of some little-understood members of the
+     leptodactylid genus _Syrrhophus_, with a description of a
+     new species. Copeia, 1954 (1):48-58.
+
+FIRSCHEIN, I. L., and SMITH, H. M.
+
+     1957. A high-crested race of toad (_Bufo valliceps_) and
+     other noteworthy reptiles and amphibians from southern
+     Mexico. Herpetologica, vol. 13 (3):219-222.
+
+FUGLER, C. M., and WEBB, R. G.
+
+     1957. Some noteworthy reptiles and amphibians from the
+     states of Oaxaca and Veracruz. Herpetologica, vol. 13
+     (2):103-108.
+
+GLOYD, H. K.
+
+     1940. The rattlesnakes, genera _Sistrurus_ and _Crotalus_.
+     Chicago Acad. Sci. Special Publ., No. 4, vii + 266 pp., pls.
+     1-31.
+
+GOIN, C. J.
+
+     1958. Comments upon the origin of the herpetofauna of
+     Florida. Quart. Jour. Florida Acad. Sci., vol. 21 (1):61-70.
+
+GOLDMAN, E. A.
+
+     1951. Biological investigations in Mexico. Smithsonian Misc.
+     Publ., vol. 115, xiii + 476 pp., pls. 1-71.
+
+GOODNIGHT, C. J., and GOODNIGHT, M. L.
+
+     1956. Some observations in a tropical rain forest in
+     Chiapas, Mexico. Ecology, vol. 37 (1):139-150.
+
+GRISCOM, L.
+
+     1932. The distribution of bird-life in Guatemala. Bull.
+     Amer. Mus. Nat. Hist., vol. 64:1-439.
+
+     1950. Distribution and origin of the birds of Mexico. Bull.
+     Mus. Comp. Zool., vol. 103:341-382.
+
+HARTWEG, N., and OLIVER, J. A.
+
+     1940. A contribution to the herpetology of the Isthmus of
+     Tehuantepec. IV. An annotated list of the amphibians and
+     reptiles collected on the Pacific slope during the summer of
+     1936. Misc. Publ. Mus. Zool. Univ. Michigan, No. 47:1-31.
+
+HUBBELL, T. H.
+
+     1954. Relationships and distribution of _Mycotrupes_. In The
+     burrowing beetles of the genus _Mycotrupes_, Olson, A. L.,
+     Hubbell, T. H., and Howden, H. F. Misc. Publ. Mus. Zool.
+     Univ. Michigan, No. 84:1-59, pls. 1-8.
+
+HUTCHINSON, G. E., PATRICK, R., and DEEVEY, E. S.
+
+     1956. Sediments of Lake Patzcuaro, Michoacán, Mexico. Bull.
+     Geol. Soc. Amer., vol. 67:1491-1504.
+
+LANGEBARTEL, D. A., and SMITH, P. W.
+
+     1959. Noteworthy records of amphibians and reptiles from
+     eastern Mexico. Herpetologica, vol. 15 (1):27-29.
+
+MARTIN, P. S.
+
+     1958. Pleistocene ecology and biogeography of North America.
+     Zoogeography. Amer. Assoc. Advanc. Sci., Publ. No.
+     51:375-420.
+
+MARTIN, P. S., and HARRELL, B. E.
+
+     1957. The Pleistocene history of temperate biotas in Mexico
+     and eastern United States. Ecology, vol. 38:468-480.
+
+OLIVER, J. A.
+
+     1948. The relationships and zoogeography of the genus
+     _Thalerophis_ Oliver. Bull. Amer. Mus. Nat. Hist., vol.
+     92:157-280, pls. 16-19.
+
+OLSON, E. C., and MCGREW, P. O.
+
+     1941. Mammalian fauna from the Pliocene of Honduras. Bull.
+     Geol. Soc. Amer., vol. 52:1219-1244.
+
+RUTHVEN, A. G.
+
+     1912. The amphibians and reptiles collected by the
+     University of Michigan--Walker Expedition in southern Vera
+     Cruz, Mexico. Zool. Jahrbuch, vol. 32 (4):295-332, pls.
+     6-11.
+
+SCHUCHERT, C.
+
+     1935. Historical geology of the Antillean-Caribbean region.
+     New York, xxvi + 811 pp.
+
+SEARS, P. B., FOREMAN, F., and CLISBY, K. H.
+
+     1955. Palynology in southern North America. Bull. Geol. Soc.
+     Amer., vol. 66:471-530.
+
+SHANNON, F. A., and WERLER, J.
+
+     1955. Notes on amphibians of the Los Tuxtlas Range of
+     Veracruz, Mexico. Trans. Kansas Acad. Sci., vol. 58
+     (3):360-386.
+
+SHREVE, B.
+
+     1957. Reptiles and amphibians from the Selva Lacandona. _In_
+     Biological Investigations in the Selva Lacandona, Chiapas,
+     Mexico. Paynter, R. A. (editor). Bull. Mus. Comp. Zool.,
+     vol. 116 (4):193-298.
+
+SMITH, H. M.
+
+     1947. Notes on Mexican amphibians and reptiles. Jour.
+     Washington Acad. Sci., vol. 37:408-412.
+
+SMITH, H. M., and LAUFE, L. E.
+
+     1946. A summary of Mexican Lizards of the genus _Ameiva_.
+     Univ. Kansas Sci. Bull., vol. 31 (2):7-73.
+
+SMITH, H. M., and TAYLOR, E. H.
+
+     1950. An annotated checklist and key to the reptiles of
+     Mexico exclusive of the snakes. Bull. U. S. Natl. Mus., No.
+     199, v + 253 pp.
+
+STIRTON, R. A.
+
+     1954. Late Miocene mammals from Oaxaca, Mexico. Amer. Jour.
+     Sci., No. 252:634-638.
+
+STUART, L. C.
+
+     1935. A contribution to a knowledge of the herpetology of a
+     portion of the savanna region of central Petén, Guatemala.
+     Misc. Publ. Mus. Zool. Univ. Michigan, No. 29:1-56, pls.
+     1-4.
+
+     1941. Studies of Neotropical Colubridae VIII. A revision of
+     the genus _Dryadophis_ Stuart, 1939. Misc. Publ. Mus. Zool.
+     Univ. Michigan, No. 49:1-106, pls. 1-4.
+
+     1951. The herpetofauna of the Guatemalan Plateau, with
+     special reference to its distribution on the southwestern
+     highlands. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+     No. 49:1-71, pls. 1-7.
+
+     1954. A description of a subhumid corridor across northern
+     Central America, with comments on its herpetofaunal
+     indicators. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+     No. 65:1-26, pls. 1-6.
+
+     1958. A study of the herpetofauna of the Uaxactun-Tikal area
+     of northern El Petén, Guatemala. Contrib. Lab. Vertebrate
+     Biol., Univ. Michigan, No. 75:1-30.
+
+TAYLOR, E. H.
+
+     1940. New species of Mexican Anura. Univ. Kansas Sci. Bull.,
+     vol. 26 (11):385-405.
+
+     1941. New amphibians from the Hobart M. Smith Mexican
+     collections. Univ. Kansas Sci. Bull., vol. 27 (8):141-167.
+
+     1942. The frog genus _Diaglena_ with a description of a new
+     species. Univ. Kansas Sci. Bull., vol. 28 (4):57-65.
+
+     1943a. A new _Hylella_ from Mexico. Proc. Biol. Soc.
+     Washington, vol. 56:49-52.
+
+     1943b. Herpetological novelties from Mexico. Univ. Kansas
+     Sci. Bull., vol. 29 (8):343-361.
+
+TAYLOR, E. H., and SMITH, H. M.
+
+     1945. Summary of the collections of amphibians made in
+     Mexico under the Walter Rathbone Bacon Traveling
+     Scholarship. Proc. U. S. Natl. Mus., vol. 95:521-613, pls.
+     18-32.
+
+TRASK, P. D., PHLEGER, F. B., and STETSON, H. C.
+
+     1947. Recent changes in sedimentation in the Gulf of Mexico.
+     Science, vol. 106:460-461.
+
+WEYL, R.
+
+     1955. Vestigios de una glaciacion del Pleistoceno en la
+     Cordillera de Talamanca, Costa Rica, A. C. Informe
+     Trimestral, Inst. Geog. de Costa Rica, pp. 9-32.
+
+WHITE, S. E.
+
+     1956. Probable substages of glaciation on Ixtaccihuatl,
+     Mexico. Jour. Geol., vol. 64:289-295.
+
+WILLIAMS, L.
+
+     1939. Arboles y arbustos del Istmos de Tehuantepec, Mexico.
+     Lilloa., vol. 4:137-171.
+
+_Transmitted May 23, 1960._
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY
+
+
+Institutional libraries interested in publications exchange may obtain
+this series by addressing the Exchange Librarian, University of Kansas
+Library, Lawrence, Kansas. Copies for individuals, persons working in a
+particular field of study, may be obtained by addressing instead the
+Museum of Natural History, University of Kansas, Lawrence, Kansas.
+There is no provision for sale of this series by the University
+Library, which meets institutional requests, or by the Museum of
+Natural History, which meets the requests of individuals. However, when
+individuals request copies from the Museum, 25 cents should be
+included, for each separate number that is 100 pages or more in length,
+for the purpose of defraying the costs of wrapping and mailing.
+
+* An asterisk designates those numbers of which the Museum's supply
+(not the Library's supply) is exhausted. Numbers published to date, in
+this series, are as follows:
+
+ Vol. 1.  Nos. 1-26 and index. Pp. 1-638, 1946-1950.
+
+*Vol. 2.  (Complete) Mammals of Washington. By Walter W. Dalquest.
+             Pp. 1-444, 140 figures in text. April 9, 1948.
+
+ Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and
+             distribution. By Rollin H. Baker. Pp. 1-359, 16 figures
+             in text. June 12, 1951.
+
+         *2. A quantitative study of the nocturnal migration of birds.
+             By George H. Lowery, Jr. Pp. 361-472, 47 figures in text.
+             June 29, 1951.
+
+          3. Phylogeny of the waxwings and allied birds. By M. Dale
+             Arvey. Pp. 473-530, 49 figures in text, 13 tables.
+             October 10, 1951.
+
+          4. Birds from the state of Veracruz, Mexico. By George H.
+             Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7
+             figures in text, 2 tables. October 10, 1951.
+
+          Index. Pp. 651-681.
+
+*Vol. 4.  (Complete) American weasels. By E. Raymond Hall. Pp. 1-466,
+             41 plates, 31 figures in text. December 27, 1951.
+
+ Vol. 5.  Nos. 1-37 and index. Pp. 1-676, 1951-1953.
+
+*Vol. 6.  (Complete) Mammals of Utah, _taxonomy and distribution_. By
+             Stephen D. Durrant. Pp. 1-549, 91 figures in text, 80
+             tables. August 10, 1952.
+
+ Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73
+             figures in text, 37 tables. August 25, 1952.
+
+          2. Ecology of the opossum on a natural area in northeastern
+             Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp.
+             305-338, 5 figures in text. August 24, 1953.
+
+          3. The silky pocket mice (Perognathus flavus) of Mexico. By
+             Rollin H. Baker. Pp. 339-347, 1 figure in text. February
+             15, 1954.
+
+          4. North American jumping mice (Genus Zapus). By Philip H.
+             Krutzsch. Pp. 349-472, 47 figures in text, 4 tables.
+             April 21, 1954.
+
+          5. Mammals from Southeastern Alaska. By Rollin H. Baker and
+             James S. Findley. Pp. 473-477. April 21, 1954.
+
+          6. Distribution of Some Nebraskan Mammals. By J. Knox Jones,
+             Jr. Pp. 479-487. April 21, 1954.
+
+          7. Subspeciation in the montane meadow mouse. Microtus
+             montanus, in Wyoming and Colorado. By Sydney Anderson.
+             Pp. 489-506, 2 figures in text. July 23, 1954.
+
+          8. A new subspecies of bat (Myotis velifer) from southeastern
+             California and Arizona. By Terry A. Vaughan. Pp. 507-512.
+             July 23, 1954.
+
+          9. Mammals of the San Gabriel mountains of California. By
+             Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12
+             tables. November 15, 1954.
+
+         10. A new bat (Genus Pipistrellus) from northeastern Mexico.
+             By Rollin H. Baker. Pp. 583-586. November 15, 1954.
+
+         11. A new subspecies of pocket mouse from Kansas. By E.
+             Raymond Hall. Pp. 587-590. November 15, 1954.
+
+         12. Geographic variation in the pocket gopher, Cratogeomys
+             castanops, in Coahuila, Mexico. By Robert J. Russell and
+             Rollin H. Baker. Pp. 591-608. March 15, 1955.
+
+         13. A new cottontail (Sylvilagus floridanus) from northeastern
+             Mexico. By Rollin H. Baker. Pp. 609-612. April 8, 1955.
+
+         14. Taxonomy and distribution of some American shrews. By
+             James S. Findley. Pp. 613-618. June 10, 1955.
+
+         15. The pigmy woodrat, Neotoma goldmani, its distribution and
+             systematic position. By Dennis G. Rainey and Rollin H.
+             Baker. Pp. 619-624. 2 figures in text. June 10, 1955.
+
+          Index. Pp. 625-651.
+
+ Vol. 8.  1. Life history and ecology of the five-lined skink, Eumeces
+             fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in
+             text. September 1, 1954.
+
+          2. Myology and serology of the Avian Family Fringillidae, a
+             taxonomic study. By William B. Stallcup. Pp. 157-211, 23
+             figures in text, 4 tables. November 15, 1954.
+
+          3. An ecological study of the collared lizard (Crotaphytus
+             collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in
+             text. February 10, 1956.
+
+          4. A field study of the Kansas ant-eating frog, Gastrophryne
+             olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in
+             text. February 10, 1956.
+
+          5. Check-list of the birds of Kansas. By Harrison B. Tordoff.
+             Pp. 307-359, 1 figure in text. March 10, 1956.
+
+          6. A population study of the prairie vole (Microtus
+             ochrogaster) in northeastern Kansas. By Edwin P. Martin.
+             Pp. 361-416, 19 figures in text. April 2, 1956.
+
+          7. Temperature responses in free-living amphibians and
+             reptiles of northeastern Kansas. By Henry S. Fitch. Pp.
+             417-476, 10 figures in text, 6 tables. June 1, 1956.
+
+          8. Food of the crow, Corvus brachyrhynchos Brehm, in
+             south-central Kansas. By Dwight Platt. Pp. 477-498, 4
+             tables. June 8, 1956.
+
+          9. Ecological observations on the woodrat, Neotoma floridana.
+             By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3
+             figures in text. June 12, 1956.
+
+         10. Eastern woodrat, Neotoma floridana: Life history and
+             ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13
+             figures in text. August 15, 1956.
+
+         Index. Pp. 647-675.
+
+ Vol. 9.  1. Speciation of the wandering shrew. By James S. Findley.
+             Pp. 1-68, 18 figures in text. December 10, 1955.
+
+          2. Additional records and extensions of ranges of mammals
+             from Utah. By Stephen D. Durrant, M. Raymond Lee, and
+             Richard M. Hansen. Pp. 69-80. December 10, 1955.
+
+          3. A new long-eared myotis (Myotis evotis) from northeastern
+             Mexico. By Rollin H. Baker and Howard J. Stains. Pp.
+             81-84. December 10, 1955.
+
+          4. Subspeciation in the meadow mouse, Microtus pennsylvanicus,
+             in Wyoming. By Sydney Anderson. Pp. 85-104, 2 figures in
+             text. May 10, 1956.
+
+          5. The condylarth genus Ellipsodon. By Robert W. Wilson.
+             Pp. 105-116, 6 figures in text. May 19, 1956.
+
+          6. Additional remains of the multituberculate genus
+             Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures
+             in text. May 19, 1956.
+
+          7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp.
+             125-335, 75 figures in text. June 15, 1956.
+
+          8. Comments on the taxonomic status of Apodemus peninsulae,
+             with description of a new subspecies from North China. By
+             J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1
+             table. August 15, 1956.
+
+          9. Extensions of known ranges of Mexican bats. By Sydney
+             Anderson. Pp. 347-351. August 15, 1956.
+
+         10. A new bat (Genus Leptonycteris) from Coahuila. By Howard
+             J. Stains. Pp. 353-356. January 21, 1957.
+
+         11. A new species of pocket gopher (Genus Pappogeomys) from
+             Jalisco, Mexico. By Robert J. Russell. Pp. 357-361.
+             January 21, 1957.
+
+         12. Geographic variation in the pocket gopher, Thomomys
+             bottae, in Colorado. By Phillip M. Youngman. Pp. 363-384,
+             7 figures in text. February 21, 1958.
+
+         13. New bog lemming (genus Synaptomys) from Nebraska. By J.
+             Knox Jones, Jr. Pp. 385-388. May 12, 1958.
+
+         14. Pleistocene bats from San Josecito Cave, Nuevo León,
+             México. By J. Knox Jones, Jr. Pp. 389-396. December 19,
+             1958.
+
+         15. New Subspecies of the rodent Baiomys from Central America.
+             By Robert L. Packard. Pp. 397-404. December 19, 1958.
+
+         16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson.
+             Pp. 405-414, 1 figure in text. May 20, 1959.
+
+         17. Distribution, variation, and relationships of the montane
+             vole, Microtus montanus. By Emil K. Urban. Pp. 415-511.
+             12 figures in text, 2 tables. August 1, 1959.
+
+         18. Conspecificity of two pocket mice, Perognathus goldmani
+             and P. artus. By E. Raymond Hall and Marilyn Bailey
+             Ogilvie. Pp. 513-518, 1 map. January 14, 1960.
+
+         19. Records of harvest mice, Reithrodontomys, from Central
+             America, with description of a new subspecies from
+             Nicaragua. By Sydney Anderson and J. Knox Jones, Jr. Pp.
+             519-529. January 14, 1960.
+
+         20. Small carnivores from San Josecito Cave (Pleistocene),
+             Nuevo León, México. By E. Raymond Hall. Pp. 531-538, 1
+             figure in text. January 14, 1960.
+
+         21. Pleistocene pocket gophers from San Josecito Cave, Nuevo
+             León, México. By Robert J. Russell. Pp. 539-548, 1 figure
+             in text. January 14, 1960.
+
+         22. Review of the insectivores of Korea. By J. Knox Jones,
+             Jr., and David H. Johnson. Pp. 549-578. February 23, 1960.
+
+         23. Speciation and evolution of the pygmy mice, genus Baiomys.
+             By Robert L. Packard. Pp. 579-670, 4 plates, 12 figures in
+             text. June 16, 1960.
+
+         Index Pp. 671-690.
+
+Vol. 10.  1. Studies of birds killed in nocturnal migration. By
+             Harrison B. Tordoff and Robert M. Mengel. Pp. 1-44, 6
+             figures in text, 2 tables. September 12, 1956.
+
+          2. Comparative breeding behavior of Ammospiza caudacuta and
+             A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates,
+             1 figure. December 20, 1956.
+
+          3. The forest habitat of the University of Kansas Natural
+             History Reservation. By Henry S. Fitch and Ronald R.
+             McGregor. Pp. 77-127, 2 plates, 7 figures in text, 4
+             tables. December 31, 1956.
+
+          4. Aspects of reproduction and development in the prairie
+             vole (Microtus ochrogaster). By Henry S. Fitch. Pp.
+             129-161, 8 figures in text, 4 tables. December 19, 1957.
+
+          5. Birds found on the Arctic slope of northern Alaska. By
+             James W. Bee. Pp. 163-211, pls. 9-10, 1 figure in text.
+             March 12, 1958.
+
+          6. The wood rats of Colorado: distribution and ecology. By
+             Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures
+             in text, 35 tables. November 7, 1958.
+
+          7. Home ranges and movements of the eastern cottontail in
+             Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3
+             figures in text. May 4, 1959.
+
+          8. Natural history of the salamander, Aneides hardyi. By
+             Richard F. Johnston and Schad Gerhard. Pp. 573-585.
+             October 8, 1959.
+
+          9. A new subspecies of lizard, Cnemidophorus sacki, from
+             Michoacán, México. By William E. Duellman. Pp. 587-598,
+             2 figures in text. May 2, 1960.
+
+         10. A taxonomic study of the Middle American Snake, Pituophis
+             deppei. By William E. Duellman. Pp. 599-610, 1 plate, 1
+             figure in text. May 2, 1960.
+
+         Index Pp. 611-626.
+
+Vol. 11.  1. The systematic status of the colubrid snake, Leptodeira
+             discolor Günther. By William E. Duellman. Pp. 1-9, 4
+             figs. July 14, 1958.
+
+          2. Natural history of the six-lined racerunner, Cnemidophorus
+             sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figs., 9
+             tables. September 19, 1958.
+
+          3. Home ranges, territories, and seasonal movements of
+             vertebrates of the Natural History Reservation. By Henry
+             S. Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3
+             tables. December 12, 1958.
+
+          4. A new snake of the genus Geophis from Chihuahua, Mexico.
+             By John M. Legler. Pp. 327-334, 2 figures in text.
+             January 28, 1959.
+
+          5. A new tortoise, genus Gopherus, from north-central
+             Mexico. By John M. Legler. Pp. 335-343. April 24, 1959.
+
+          6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By
+             Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in
+             text, 10 tables. May 6, 1959.
+
+          7. Fishes of the Big Blue River Basin, Kansas. By W. L.
+             Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5
+             tables. May 8, 1959.
+
+          8. Birds from Coahuila, México. By Emil K. Urban. Pp.
+             443-516. August 1, 1959.
+
+          9. Description of a new softshell turtle from the
+             southeastern United States. By Robert G. Webb. Pp.
+             517-525, 2 pls., 1 figure in text, August 14, 1959.
+
+         10. Natural history of the ornate box turtle, Terrapene
+             ornata ornata Agassiz. By John M. Legler. Pp. 527-669,
+             16 pls., 29 figures in text. March 7, 1960.
+
+         Index will follow.
+
+Vol. 12.  1. Functional morphology of three bats: Eumops, Myotis,
+             Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24
+             figures in text, July 8, 1959.
+
+          2. The ancestry of modern Amphibia: a review of the
+             evidence. By Theodore H. Eaton, Jr. Pp. 155-180, 10
+             figures in text. July 10, 1959.
+
+          3. The baculum in microtine rodents. By Sydney Anderson.
+             Pp. 181-216, 49 figures in text. February 19, 1960.
+
+          4. A new order of fishlike Amphibia from the Pennsylvanian
+             of Kansas. By Theodore H. Eaton, Jr., and Peggy Lou
+             Stewart. Pp. 217-240, 12 figures in text. May 2, 1960.
+
+          More numbers will appear in volume 12.
+
+Vol. 13.  1. Five natural hybrid combinations in minnows (Cyprinidae).
+             By Frank B. Cross and W. L. Minckley. Pp. 1-18. June 1,
+             1960.
+
+          2. A distributional study of the amphibians of the isthmus
+             of Tehuantepec, México. By William E. Duellman.
+             Pp. 19-72, pls. 1-8, 3 figs. August 16, 1960.
+
+          More numbers will appear in volume 13.
+
+       *       *       *       *       *
+
+
+Transcriber's Notes
+
+
+Page 26: Changed "19. Cosaleacaque" to "19. Cosoleacaque".
+
+Page 30: Changed "Brysonima crassifolia" to "Byrsonima crassifolia".
+
+Page 34: Changed "long. 95' 29°;" to "long. 95° 29';".
+
+Page 35: Changed "Matías Romera" to "Matías Romero".
+
+Page 47: Changed "kown" to "known".
+
+Pages 50 and 59: Changed "axills" to "axils".
+
+Plate 1, Fig. 2: Changed "Veracuz" to "Veracruz".
+
+Page 53: Changed "valadity" to "validity".
+
+Page 61, Table 1: Changed male symbol to "(Male)" (plain text version).
+
+Page 67: Changed "refering" to "referring".
+
+Page 68: Changed "survided" to "survived".
+
+Page 71: Changed "subhimid" to "subhumid" and "Amerca" to "America".
+
+Moved University of Kansas Publications list to end of report.
+Vol. 9, No. 12: Changed pages from "363-387" to "363-384".
+Vol. 10, No. 10: Changed pages from "599-612" to "599-610".
+
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of A Distributional Study of the
+Amphibians of the Isthmus of Tehuantepec, Mexico, by William E. Duellman
+
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+    <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1" />
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+    <title>
+      The Project Gutenberg eBook of A Distributional Study of the Amphibians
+of the Isthmus of Tehuantepec, México, by William E. Duellman.
+    </title>
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+
+
+<pre>
+
+The Project Gutenberg EBook of A Distributional Study of the Amphibians of
+the Isthmus of Tehuantepec, Mexico, by William E. Duellman
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, Mexico
+
+Author: William E. Duellman
+
+Release Date: December 30, 2011 [EBook #38440]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK A DISTRIBUTIONAL STUDY OF ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+
+
+
+
+<hr class="tb" />
+<p class="title">
+<span class="smcap">University of Kansas Publications</span><br />
+<span class="smcap">Museum of Natural History</span></p>
+<hr class="r5" />
+<p class="title">Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.<br />
+
+August 16, 1960</p>
+<hr class="tb" />
+
+<h1>A Distributional Study of the Amphibians<br />
+of the Isthmus of Tehuantepec, México</h1>
+
+<p class="title">BY<br />
+WILLIAM E. DUELLMAN<br /><br /><br />
+
+<span class="smcap">University of Kansas</span><br />
+<span class="smcap">Lawrence</span><br />
+1960
+</p>
+
+
+<p><span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span></p>
+<hr class="tb" />
+<p class="title">
+<span class="smcap">University of Kansas Publications</span><br />
+<span class="smcap">Museum of Natural History</span></p>
+<hr class="r5" />
+<p class="title">Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.<br />
+
+August 16, 1960</p>
+<hr class="tb" />
+
+<h1>A Distributional Study of the Amphibians<br />
+of the Isthmus of Tehuantepec, México</h1>
+
+<p class="title">BY<br />
+WILLIAM E. DUELLMAN<br /><br /><br />
+
+<span class="smcap">University of Kansas</span><br />
+<span class="smcap">Lawrence</span><br />
+1960
+</p>
+<hr class="chap" />
+
+
+<p><span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span></p>
+<p class="title">
+<span class="smcap">University of Kansas Publications, Museum of Natural History</span><br />
+<br />
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,<br />
+Robert W. Wilson<br />
+<br />
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.<br />
+Published August 16, 1960<br />
+<br />
+<span class="smcap">University of Kansas</span><br />
+Lawrence, Kansas<br />
+<br />
+<small>PRINTED IN</small><br />
+<small>THE STATE PRINTING PLANT</small><br />
+<small>TOPEKA, KANSAS</small><br />
+<small>1960</small><br />
+<br />
+28-3859<br />
+</p>
+
+
+
+<hr class="chap" /><p><span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span></p>
+<h2>A Distributional Study of the Amphibians<br />
+of the Isthmus of Tehuantepec, México</h2>
+
+<p class="title">BY<br /><br />
+
+WILLIAM E. DUELLMAN</p>
+
+<hr class="r5" />
+
+
+<h2><a name="CONTENTS" id="CONTENTS"></a>CONTENTS</h2>
+
+
+<div class="center">
+<table border="0" cellpadding="4" cellspacing="0" summary="toc">
+<tr><th align="left">&nbsp;</th><th align="right"><small>PAGE</small></th></tr>
+<tr><td align="left"><span class="smcap">Introduction</span></td><td align="right"><a href="#INTRODUCTION">21</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Acknowledgments</span></td><td align="right"> <a href="#Page_23">23</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Field Studies in the Isthmus of Tehuantepec</span></td><td align="right"><a href="#Page_23">23</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Sources of Material</span></td><td align="right"><a href="#Page_24">24</a></td></tr>
+<tr><td align="left"><span class="smcap">Description of the Isthmus of Tehuantepec</span></td><td align="right"><a href="#Page_25">25</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Physiography</span></td><td align="right"><a href="#Page_25">25</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Climate</span></td><td align="right"><a href="#Page_28">28</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Vegetation</span></td><td align="right"><a href="#Page_29">29</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">The Sierra de los Tuxtlas</span></td><td align="right"><a href="#Page_32">32</a></td></tr>
+<tr><td align="left"><span class="smcap">Gazetteer</span></td><td align="right"><a href="#Page_33">33</a></td></tr>
+<tr><td align="left"><span class="smcap">The Amphibian Fauna of the Lowlands</span></td><td align="right"><a href="#Page_37">37</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Composition of the Fauna</span></td><td align="right"><a href="#Page_37">37</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Ecology of the Fauna</span></td><td align="right"><a href="#Page_38">38</a></td></tr>
+<tr><td align="left"><span style="margin-left: 1em;">Distribution of the Fauna</span></td><td align="right"><a href="#Page_42">42</a></td></tr>
+<tr><td align="left"><span class="smcap">The Amphibian Fauna of the Foothills and Adjacent Highlands</span></td><td align="right"><a href="#Page_44">44</a></td></tr>
+<tr><td align="left"><span class="smcap">Establishment of Present Patterns of Distribution</span></td><td align="right"><a href="#Page_45">45</a></td></tr>
+<tr><td align="left"><span class="smcap">Accounts of Species</span></td><td align="right"><a href="#Page_49">49</a></td></tr>
+<tr><td align="left"><span class="smcap">Summary</span></td><td align="right"><a href="#Page_68">68</a></td></tr>
+<tr><td align="left"><span class="smcap">Literature Cited</span></td><td align="right"><a href="#Page_69">69</a></td></tr>
+</table></div>
+
+
+
+
+<h2><a name="INTRODUCTION" id="INTRODUCTION"></a>INTRODUCTION</h2>
+
+
+<p>Few regions in Middle America are so important zoogeographically as is
+the Isthmus of Tehuantepec, that neck of land connecting North America
+with Central America, separating the Pacific Ocean from the Gulf of
+Mexico by a distance of only about 220 kilometers (airline), and
+forming a low break between the highlands of México and those of
+Central America. Before World War II the isthmus could be reached
+readily only by railroad or by ocean vessel to Salina Cruz or
+Coatzacoalcos. With the advent of roads, principally the Trans-isthmian
+Highway, vast areas of the interior of the isthmus became accessible to
+biologists. Nevertheless, long before roads were built in the isthmian
+region collectors and biologists visited it, especially the town of
+Tehuantepec, from which collections date back to the 1870's. Therefore,
+it is rather<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span>
+surprising that no attempt has been made to present a
+faunal list of the amphibians or reptiles of the isthmus. Ruthven
+(1912) summarized his collections from the vicinity of Cuatotolapam,
+Veracruz, and Hartweg and Oliver (1940) presented an annotated list of
+the species collected by them in the vicinity of Tehuantepec. In recent
+years there have been only a few papers reporting species from the
+isthmus (Fugler and Webb, 1957; Langebartel and Smith, 1959). The
+zoogeographic significance of the Isthmus of Tehuantepec is exemplified
+by the works of Burt (1931), Duellman (1958), Gloyd (1940), Oliver
+(1948), and Stuart (1941), who in their discussions of evolution and
+dispersal of various genera of reptiles, pointed out that the Isthmus
+of Tehuantepec was a region of zoogeographic importance.</p>
+
+<p>Originally I intended to study the entire herpetofauna of the isthmus.
+But I have not had opportunity to study all of the reptiles, and I have
+not had the inclination to solve certain taxonomic problems concerning
+them. The amphibians that I collected, together with all other known
+specimens in museums, have been studied. Therefore, the present report
+is concerned only with the amphibians. Only the amphibians of the
+lowlands of the isthmus have been sampled adequately. Although I have
+commented on the highland species in the discussion of distribution,
+they are not included in the systematic section, which deals solely
+with the 36 species definitely known to occur in the lowlands of the
+isthmus.</p>
+
+<p>Among the species of amphibians that I would expect to occur in the
+isthmus, the only one not yet found there is <i>Hyla phaeota</i>. Sufficient
+specimens of most of the species are available to show their variation
+in the isthmus. Consequently, the systematics of these amphibians is on
+a fairly substantial basis. Probably certain species in the isthmian
+region will be found to be conspecific with others to the south, for
+example <i>Hyla ebraccata</i> with <i>Hyla leucophyllata</i> and <i>Hyla
+robertmertensi</i> with <i>Hyla underwoodi</i>. Nevertheless, such taxonomic
+changes will not affect the distributional picture presented here. Our
+greatest lack of knowledge concerning the amphibians is about their
+life histories, as may be illustrated by the following questions, all
+of which now are without definite answers. Where do many of the small
+frogs conceal themselves during the dry season? What amount of, if any,
+interspecific competition exists among several species of tree frogs,
+all of which breed in the same ponds? What factors in the environment
+permit certain amphibians, but not others, to live in the<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span>
+humid rainforests, as well as in the arid tropical scrub forest? The answers
+to these questions and many others must await additional field studies.</p>
+
+<p>The purpose of this paper is to make known the species of amphibians
+living in the Isthmus of Tehuantepec, to describe the environments in
+which they live, and to discuss their distribution in the isthmus. With
+respect to the distribution of animals in the Isthmus of Tehuantepec I
+will attempt to explain the present patterns of distribution with
+special reference to climatic fluctuation in the Pleistocene.</p>
+
+
+<h3><i>Acknowledgments</i></h3>
+
+<p>My extensive field work in the Isthmus of Tehuantepec was made possible
+by grants from the Penrose Fund of the American Philosophical Society
+(1956) and the Bache Fund of the National Academy of Sciences (1958).
+Furthermore, my field work received the hearty support of the Museum of
+Zoology at the University of Michigan; for their cooperation I am
+indebted to Norman Hartweg, T. H. Hubbell, and Henry van der Schalie.
+In the course of my studies I received helpful suggestions from Norman
+Hartweg, L. C. Stuart, and Charles F. Walker, to whom I am grateful.
+For permission to examine specimens in their care I thank Doris M.
+Cochran, Hobart M. Smith, and Richard G. Zweifel. I am deeply indebted
+to Thomas MacDougall for many suggestions and for aid in preparing the
+gazetteer. I am most grateful for the efforts of my field companions,
+Richard E. Etheridge, Jerome B. Tulecke, John Wellman, and especially
+my wife, Ann S. Duellman, who spent many long days and nights gathering
+much of the data on which this report is based. Our work in the isthmus
+was furthered by the generous help and hospitality of many residents,
+especially the late Wilbur Barker of Tehuantepec, Fortunado Delgado of
+Rancho Las Hojitas near Acayucan, César Fárjas of Donají, and Juan
+Mayol of San Andrés Tuxtla. Profesor Jordi Juliá Z. of the Laboratorio
+de Entomología, Comisión del Papaloapan, Ciudad Alemán, Veracruz,
+helped make possible my field work in 1959; for this he has my sincere
+thanks. In conclusion I express my gratitude to Ing. Juan Lozano
+Franco, Secretaria de Agricultura y Ganadería, for providing me with
+the necessary permits.</p>
+
+
+<h3><i>Field Studies in the Isthmus of Tehuantepec</i></h3>
+
+<p>I first visited the Isthmus of Tehuantepec and collected on the Pacific
+lowlands of the isthmus in July, 1955. At that time heavy rains and
+impassable roads restricted travelling. In February and March of 1956
+my wife and I concentrated our efforts in the central region between
+the Río Jaltepec and Matías Romero, but also made several trips across
+the isthmus to gather ecological data in the dry season. In July of the
+same year, accompanied by Richard E. Etheridge, we again crossed the
+isthmus several times in order to gather ecological data in the wet
+season, and studied especially hylid frogs, most of which had not been
+seen in the dry season. Accompanied by Jerome B. Tulecke and John
+Wellman, I collected again in the isthmus in July, 1958, between Salina
+Cruz and Tehuantepec, and between Coatzacoalcos and<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span> Cosoleacaque. In
+March and April, 1959, I collected at Ciudad Alemán. Nearly 1200
+specimens of 30 species of amphibians were thus collected in the
+Isthmus of Tehuantepec; all specimens are now in the Museum of Zoology
+at the University of Michigan. Of other species known from the isthmus,
+I have had field experience with all but one (<i>Bolitoglossa
+veracrucis</i>) in other parts of México.</p>
+
+
+<h3><i>Sources of Material</i></h3>
+
+<p>There are in museum collections nearly 3000 specimens of amphibians
+with reliable data from the Isthmus of Tehuantepec. Among the first
+herpetological specimens collected in the isthmian region are those
+assembled by Francis Sumichrast in the 1870's from the vicinity of
+Santa Efigenia and Tapanatepec, Oaxaca. These specimens were sent to
+the United States National Museum and the Museum National d'Histoire
+Naturelle in Paris; many served as the types of new species: <i>Bufo
+canaliferus</i> Cope, <i>Eleutherodactylus rugulosus</i> Cope, <i>Syrrhophus
+leprus</i> Cope, and <i>Hylella sumichrasti</i> Brocchi. In 1911 Alexander G.
+Ruthven collected in the savanna country near Cuatotolapam, Veracruz;
+the report on his collections (1912) is the first dealing with the
+herpetofauna of a part of the isthmus. His specimens are in the
+collection of the University of Michigan Museum of Zoology. Norman
+Hartweg and James A. Oliver collected for the University of Michigan
+Museum of Zoology in the vicinity of Tehuantepec, Oaxaca, during the
+summer of 1936. The results of their work were published as an
+annotated list of species occurring on the Pacific slopes of the
+isthmus (1940). Hobart M. Smith collected in the vicinity of
+Tehuantepec in January, 1940; his specimens are in the United States
+National Museum. Specimens collected by Smith served as the types of
+<i>Eleutherodactylus avocalis</i> Taylor and Smith and <i>Diaglena reticulata</i>
+Taylor. Walter W. Dalquest collected vertebrates for the University of
+Kansas in southern Veracruz in the winters of 1947 and 1948; he spent
+about six months on the Gulf lowlands of the isthmus, principally in
+the vicinity of Jesús Carranza. For the past two decades Thomas
+MacDougall, a resident of New York City, has spent his winters
+collecting biological specimens in southern México. He makes his
+headquarters at Tehuantepec, but his compulsion to see the "back
+country" has taken him to many remote parts of southern Oaxaca. His
+earlier collections are in the American Museum of Natural History; the
+later ones are in the University of Illinois Museum of Natural History.</p>
+
+<p>Minor collections include those made by Matthew W. Stirling at San
+Lorenzo, Veracruz, February-April, 1946 (United States National
+Museum), by Fred G. Thompson on a trip across the isthmus in December,
+1955 (University of Michigan Museum of Zoology), by the University of
+Kansas Museum of Natural History field party under the direction of
+Rollin H. Baker at Tolosita, Oaxaca, and by David A. Langebartel and
+associates from southern Oaxaca in June, 1958 (University of Illinois
+Museum of Natural History).</p>
+
+<p>In the collections of the United States National Museum are several
+species of amphibians sent to the museum from Tehuantepec by Francis
+Sumichrast. These include <i>Bolitoglossa platydactyla</i> (USNM 30305,
+30344-6, 30528), <i>Bolitoglossa rufescens</i> (10042), <i>Chiropterotriton
+chiropterus</i> (30347), <i>Lineatriton lineola</i> (30353), <i>Parvimolge
+townsendi</i> (30352), <i>Pseudoeurycea cephalica</i> (30350), <i>Thorius
+pennatulus</i> (30348-9), <i>Hyla miotympanum</i> (30302-3),<span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span> and <i>Hyla picta</i>
+(30304). Because of the poor condition of the specimens, determinations
+of those listed as <i>Bolitoglossa rufescens</i> and <i>Pseudoeurycea
+cephalica</i> are uncertain. With the exception of the <i>Bolitoglossa
+rufescens</i>, which is stated to have come from Santa Efigenia, all of
+these specimens are catalogued as having come from Tehuantepec. None of
+these species has since been recorded from the Pacific slopes of the
+isthmus; however, they all occur in the vicinity of Orizaba, Veracruz.
+Probably Sumichrast carried the specimens with him from Orizaba, his
+home before moving to Santa Efigenia, and shipped them from Tehuantepec
+to the United States National Museum. These species definitely should
+not be considered as inhabitants of the Pacific slopes of the Isthmus
+of Tehuantepec.</p>
+
+
+
+
+<h2><a name="DESCRIPTION_OF_THE_ISTHMUS_OF_TEHUANTEPEC" id="DESCRIPTION_OF_THE_ISTHMUS_OF_TEHUANTEPEC"></a>DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC</h2>
+
+
+<p>The Isthmus of Tehuantepec is a strip of land forming a low pass, which
+separates the mountain masses of México proper from those of Central
+America, and at the same time provides a continuum of lowlands from the
+Gulf of Mexico to the Pacific Ocean. This topography combines with the
+climatic conditions to create extremely diverse environments, the
+distribution of which can be adequately understood only after an
+acquaintance with the topography and climate of the region.</p>
+
+
+<h3><i>Physiography</i></h3>
+
+<p>In east-central Oaxaca the mountain masses comprising the Sierra Madre
+Oriental and the Sierra del Sur terminate in a series of ranges&mdash;Sierra
+de Juárez, Sierra de los Míjes, and Sierra de Choapam. From lofty
+peaks, such as Cerro de Zempoaltepetl (3400 meters), the highlands
+diminish eastward to succeedingly lower ridges, until in the middle of
+the Isthmus of Tehuantepec the continental divide is about 250 meters
+above sea level. Eastward from this low divide the land rises to form
+the Sierra Madre de Chiapas, which is continuous with the highland
+masses of Guatemala.</p>
+
+<p>For the purposes of this description, the lowlands of the isthmus may
+be divided into three parts&mdash;the Gulf Coastal Plain, the central
+ridges, and the Pacific Coastal Plain, which in the isthmus is called
+the Plains of Tehuantepec (<a href="#fig1">Figs. 1</a> and <a href="#fig2">2</a>).</p>
+
+<p>The Gulf Coastal Plain is broad and fairly level near the coast, but
+rolling in the interior. The plain, throughout most of its length in
+the isthmus, is at least 75 kilometers wide. The majority of the region
+in the isthmus is drained by the Río Coatzacoalcos, which flows in a
+northerly course to the Gulf of Mexico. The western part is drained by
+the Río San Juan, the principal tributary of the Río Papaloapan. Behind
+the coastal dunes are frequent, and sometimes<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span> large, lagoons.
+Immediately inland from Coatzacoalcos and along the lower stretches of
+the Río Papaloapan are extensive marshes. Essentially the entire
+coastal plain, with the exception of the coastal dunes, consists of
+rich alluvial deposits.</p>
+
+<div class="figcenter" style="width: 416px;">
+<a name="fig1" id="fig1"></a>
+<a href="images/i_010g.jpg">
+<img src="images/i_010.jpg" width="416" height="600" alt="Fig. 1. Map of the Isthmus of Tehuantepec based on the
+American Geographical Society's Map of Hispanic America on the Scale
+of 1:1,000,000.
+
+The localities shown are numbered in the gazetteer; the numerical
+sequence of localities is an arrangement whereby north takes precedence
+over south and west over east. 1. Alvarado. 2. Lerdo de Tejada. 3.
+Tlacotalpan. 4. Tula. 5. Tecolapan. 6. Amatitlán. 7. Cosamaloapan. 8.
+Chacaltianguis. 9. Novillero. 10. Ciudad Alemán. 11. Papaloapan. 12.
+Tuxtepec. 13. Cuatotolapam. 14. Hueyapan. 15. Berta. 16. Coatzacoalcos.
+17. Ayentes. 18. Río de las Playas. 19. Cosoleacaque. 20. Minatitlán.
+21. Acayucan. 22. Aquilera. 23. San Lorenzo. 24. Naranja. 25. Suchil.
+26. Jesús Carranza. 27. La Oaxaqueña. 28. Ubero. 29. Donají. 30.
+Tolosita. 31. El Modelo. 32. Sarabia, 33. Guichicovi. 34. La Princesa.
+35. Santa María Chimalapa. 36. Matías Romero. 37. Santo Domingo Petapa.
+38. El Barrio. 39. Palmar. 40. Chivela. 41. Santiago Chivela. 42.
+Nizanda. 43. Agua Caliente. 44. Portillo Los Nanches. 45. Ixtepec. 46.
+La Ventosa. 47. Zanatepec. 48. Unión Hidalgo. 49. Tres Cruces. 50.
+Juchitán. 51. Escurano. 52. Salazar. 53. Santa Efigenia. 54.
+Tequisistlán. 55. Cerro de Quiengola. 56. San Pablo. 57. Mixtequilla.
+58. Tapanatepec. 59. Zarzamora. 60. Limón. 61. Tehuantepec. 62.
+Bisilana. 63. Santa Lucía. 64. Cerro de Arenal. 65. Cerro de San Pedro.
+66. La Concepción. 67. Tenango. 68. San Antonio. 69. Huilotepec. 70.
+Salina Cruz." /></a>
+<span class="caption"><span class="smcap">Fig. 1.</span> Map of the Isthmus of Tehuantepec based on the
+American Geographical Society&#39;s &quot;Map of Hispanic America on the Scale
+of 1:1,000,000.&quot;<br /><small>(Click image for larger view.)</small><br /><br />
+
+The localities shown are numbered in the gazetteer; the numerical
+sequence of localities is an arrangement whereby north takes precedence
+over south and west over east. 1. Alvarado. 2. Lerdo de Tejada. 3.
+Tlacotalpan. 4. Tula. 5. Tecolapan. 6. Amatitlán. 7. Cosamaloapan. 8.
+Chacaltianguis. 9. Novillero. 10. Ciudad Alemán. 11. Papaloapan. 12.
+Tuxtepec. 13. Cuatotolapam. 14. Hueyapan. 15. Berta. 16. Coatzacoalcos.
+17. Ayentes. 18. Río de las Playas. 19. Cosoleacaque. 20. Minatitlán.
+21. Acayucan. 22. Aquilera. 23. San Lorenzo. 24. Naranja. 25. Suchil.
+26. Jesús Carranza. 27. La Oaxaqueña. 28. Ubero. 29. Donají. 30.
+Tolosita. 31. El Modelo. 32. Sarabia, 33. Guichicovi. 34. La Princesa.
+35. Santa María Chimalapa. 36. Matías Romero. 37. Santo Domingo Petapa.
+38. El Barrio. 39. Palmar. 40. Chivela. 41. Santiago Chivela. 42.
+Nizanda. 43. Agua Caliente. 44. Portillo Los Nanches. 45. Ixtepec. 46.
+La Ventosa. 47. Zanatepec. 48. Unión Hidalgo. 49. Tres Cruces. 50.
+Juchitán. 51. Escurano. 52. Salazar. 53. Santa Efigenia. 54.
+Tequisistlán. 55. Cerro de Quiengola. 56. San Pablo. 57. Mixtequilla.
+58. Tapanatepec. 59. Zarzamora. 60. Limón. 61. Tehuantepec. 62.
+Bisilana. 63. Santa Lucía. 64. Cerro de Arenal. 65. Cerro de San Pedro.
+66. La Concepción. 67. Tenango. 68. San Antonio. 69. Huilotepec. 70.
+Salina Cruz.</span>
+</div>
+
+<hr class="tb" /><p><span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span></p>
+
+<div class="figcenter" style="width: 800px;">
+<a name="fig2" id="fig2"></a>
+<img src="images/i_011.png" width="800" height="342" alt="Fig. 2. Topographic profile of the Isthmus of
+Tehuantepec showing major localities along the Trans-isthmian Highway
+and major types of vegetation. Vertical exaggeration approximately 165
+times."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Topographic profile of the Isthmus of
+Tehuantepec showing major localities along the Trans-isthmian Highway
+and major types of vegetation. Vertical exaggeration approximately 165
+times.</span>
+</div>
+<p><span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span></p>
+
+<p>The central ridges extend from the Río Jaltepec southward to within 40
+kilometers of the Pacific coast. It is in this area that the continuity
+of the high ridges and volcanic peaks, which extend nearly the entire
+length of the Americas, is interrupted at a point almost directly in
+line with the shortest distance between the two oceans. The northern
+part of this central region consists of hills dissected by tributaries
+of the Río Coatzacoalcos; the principal ones from north to south
+are&mdash;Río Jaltepec, Río Tortuguero, Río Sarabia, and Río Malatengo. The
+plains of Chivela are south of these rivers and lie at an elevation of
+about 200 meters; at the southern edge of these plains a range of hills
+rises to 250 to 400 meters above sea level. These hills drop abruptly
+to the Plains of Tehuantepec. In the northern and central parts of this
+central region the rocks are granitic; the hills to the south of the
+Plains of Chivela are limestone.</p>
+
+<p>The Pacific Coastal Plain or Plains of Tehuantepec have a maximum width
+of about 30 kilometers. From the base of the hills at an elevation of
+about 75 meters the plains slope gradually to the sea. To the west of
+the Río Tehuantepec and to the east of the Plains of Tehuantepec at the
+base of the Sierra Madre de Chiapas, the coastal plain becomes much
+narrower; in these places the continuity of the plain is frequently
+interrupted by low north-south ridges extending outward from the
+mountains or by isolated hills. The soil is poor, varying from volcanic
+rock to gravel and sand.</p>
+
+
+<h3><i>Climate</i></h3>
+
+<p>The prevailing winds are from the north across the Gulf of Mexico.
+These moisture-laden winds precipitate most of their moisture north of
+the central ridges. This results in high rainfall on the northern
+slopes and Gulf Coastal Plain and relatively little rainfall on the
+southern slopes and the Pacific Coastal Plain. Precipitation is cyclic;
+there is a marked wet and a dry season throughout the region, but this
+is most noticeable on the Pacific lowlands (<a href="#fig3">Fig. 3</a>). At Salina Cruz on
+the Pacific Ocean the average annual rainfall is 1040 mm. (Contreras,
+1942); of this amount, only 15 mm. falls from November through April.
+On the Gulf Coastal Plain (Minatitlán station) the average annual<span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span>
+rainfall is 3085 mm. In this region the driest months are February
+through May, during which time 236 mm. of rain falls. At Salina Cruz
+the wettest month is June; at Minatitlán it is September. There is
+little variation in temperature throughout the isthmus; the average
+annual temperature at Salina Cruz is 26.6° C.; that at Minatitlán is
+26.2° C. During the winter when masses of air from the arctic move
+southward into the Great Plains of the United States, cool winds blow
+across the isthmus. These are usually accompanied by overcast sky and
+sometimes a slight amount of precipitation. These "nortes" may cause a
+drop in temperature of about six to eight degrees in a few hours.</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="fig3" id="fig3"></a>
+<img src="images/i_013.png" width="600" height="314" alt="Fig. 3. Climatographs for Minatitlán, Veracruz, and
+Salina Cruz, Oaxaca, based on data given by Contreras (1942). Plotted
+points are for mean monthly temperatures and rainfall; months are
+indicated by numbers."/>
+<span class="caption"><span class="smcap">Fig. 3.</span> Climatographs for Minatitlán, Veracruz, and
+Salina Cruz, Oaxaca, based on data given by Contreras (1942). Plotted
+points are for mean monthly temperatures and rainfall; months are
+indicated by numbers.</span>
+</div>
+
+
+<h3><i>Vegetation</i></h3>
+
+<p>The topography and climate combine to produce drastically different
+types of climax vegetation on the northern and southern lowlands of the
+isthmus. The picture is somewhat complicated by the savannas on the
+Gulf Coastal Plain, which, as will be shown later, are dependent upon
+edaphic features more than climatic conditions. The following brief
+account of the vegetation in the Isthmus of Tehuantepec is based on
+data provided by Williams (1939) and Goldman (1951), supplemented by
+personal observations. The purpose of this description is not to
+analyze the flora of the isthmus, but to give the reader a picture of
+this aspect of the biota of the major environments with which I shall
+be concerned in the ensuing discourse on the amphibians of the region.<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span>
+The three divisions of the isthmus recognized in the account of the
+physiography serve equally well in describing the vegetation. Those
+divisions are as follows:</p>
+
+<h4>Gulf Lowlands</h4>
+
+<p>On the lowlands north of the continental divide and extending to the
+Gulf of Mexico are three major types of vegetation&mdash;tropical
+rainforest, arid tropical scrub forest, and savanna. Aside from these,
+there are marshes and lagoons near the coast.</p>
+
+<p>On the coastal dunes there are thickets of sea grape, patches of
+<i>Cenchrus</i>, and clumps or scattered <i>Opuntia</i>. The lagoons are bordered
+by mangrove thickets made up primarily of <i>Lonchocarpus hondurensis</i>.
+In the marshes along the lower Río Coatzacoalcos and Río Papaloapan the
+tall tough grass, <i>Gynerium sagittatum</i>, is common.</p>
+
+<p>According to Beard (1953: 291) the development of savanna vegetation is
+dependent upon soil, topography, and drainage. Level regions having
+permeable soil horizons lying on top of an impermeable horizon provide
+poor drainage. In most savanna regions in the Americas the grasslands
+become waterlogged or even partly flooded during the rainy season and
+desiccated in the dry season. Many ecologists and phytogeographers have
+postulated that savannas are either man made or are examples of a fire
+climax. Beard (<i>op. cit.</i>: 203) provided multitudinous evidence that
+the association of savanna vegetation and certain types of edaphic and
+topographic conditions was so strongly marked that grassland is the
+natural vegetation in these areas.</p>
+
+<p>Savannas are scattered through southern Veracruz eastward to British
+Honduras. These usually are grasslands having scattered trees or clumps
+of trees around depressions, which may contain water throughout the
+year (<a href="#pl1-fig1">Pl. 1, fig. 1</a>). According to Williams (<i>op. cit.</i>), the most
+common trees in the savannas in southern Veracruz are <i>Ceiba
+pentandra</i>, <i>Chlorophora tinctoria</i>, and <i>Byrsonima crassifolia</i>.</p>
+
+<p>Lying in a rain shadow cast by the Tuxtlas and on sandy and
+well-drained soils is a dense xerophytic forest. The crown of this
+deciduous forest usually is little more than ten to twelve meters above
+the ground (<a href="#pl1-fig2">Pl. 1, fig. 2</a>). Conspicuous trees in this scrub forest are
+<i>Acacia cornigera</i>, <i>Bauhinia latifolia</i>, <i>Calliandra bijuga</i>, <i>Cassia
+laevigata</i>, <i>Guazuma ulmifolia</i>, and various species of <i>Bursera</i>.</p>
+
+<p>The most extensive type of vegetation on the Gulf Coastal Plain is a
+tall evergreen forest resembling tropical rainforest. Although<span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span> this
+forest is made up of many species of trees that are characteristic of
+true rainforest, the forest on the Gulf Coastal Plain cannot be
+classified as true rainforest, neither by the climatic conditions, nor
+the structure of the forest. The seasonal variation in rainfall
+probably is the chief factor in hindering the development of a
+rainforest climax vegetation. Usually a minimum of 65 mm. of rainfall
+each month is considered essential for the development of true
+rainforest. At Minatitlán the average rainfall for March (39 mm.) and
+April (36 mm.) is far below this minimum. Structurally, this forest has
+a crown about 30-35 meters above the ground but individual trees rising
+five meters or more above the crown (<a href="#pl2-fig1">Pl. 2, figs. 1</a>-<a href="#pl2-fig2">2</a>). There is no
+clear stratification within the forest; in many parts of it there are
+dense growths of bushes, small trees, and palms. The forest on the Gulf
+Coastal Plain, therefore, most properly might be referred to as a
+quasi-rainforest, a term that has been applied to other such forests in
+tropical America.</p>
+
+<p>Among the abundant and dominant trees in this forest are <i>Swietenia
+macrophylla</i>, <i>Calophyllum brasiliense</i>, <i>Achras zapota</i>, <i>Ceiba
+pentandra</i>, <i>Castilla elastica</i>, <i>Cedrela mexicana</i>, <i>Tabebuia
+Donnell-Smithi</i>, <i>Calocarpum mammosum</i>, <i>Bombax ellipticum</i>, and a
+variety of <i>Ficus</i>. Epiphytes and Ilianas are abundant.</p>
+
+<h4>Central Ridges</h4>
+
+<p>The vegetation of the central ridges of the isthmus is, for the most
+part, transitional between the tall rainforest of the Gulf Coastal
+Plain and the low xerophytic scrub forest of the semi-arid Pacific
+Coastal Plain. On the northern slopes of the ridges the rainforest is
+more poorly developed than on the plains to the north. Many of the same
+species of trees are present, including <i>Ceiba pentandra</i>, <i>Cedrela
+mexicana</i>, <i>Swietenia macrophylla</i>, and <i>Ficus</i> sp.; nevertheless,
+these seldom are as large as members of the same species in the forest
+on the plains. Other species present on the forested slopes include
+<i>Tabebuia Donnell-Smithi</i>, <i>Zanthoxylum melanostictum</i>, <i>Pithecolobium
+arboreum</i>, and a species of <i>Pterocarpus</i>. The structure of this forest
+differs from that on the Gulf Coastal Plain in that there is no
+continuous upper canopy and there is a dense undergrowth (<a href="#pl3-fig1">Pl. 3, fig.1</a>).
+This type of forest extends from Mogoñe southward to about Matías
+Romero.</p>
+
+<p>In the vicinity of Matías Romero open pine-oak forest (<i>Pinus caribaea</i>
+and <i>Quercus</i> sp.) is found on some ridges as low as 250 meters above
+sea level.</p>
+
+<p>On the Plains of Chivela in the southern part of the central region<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span>
+the vegetation takes on a semi-arid appearance, especially in a savanna
+on the plains. Clumps of small trees and bushes, consisting of <i>Croton
+nivea</i>, <i>Cordia cana</i>, <i>Jacquinia aurantiaca</i>, <i>Calycophyllum
+candidissimum</i>, and <i>Cassia emarginata</i>, are scattered on a grassy
+plain, from which rise widely-spaced palms of an unknown species (<a href="#pl3-fig2">Pl. 3, fig. 2</a>).</p>
+
+<h4>Pacific Coastal Plain</h4>
+
+<p>The vegetation of the Pacific lowlands definitely is semi-arid in
+character. Most of the trees are deciduous, thorny, and short. During
+the dry season the landscape presents a barren appearance, but shortly
+after the first summer rains dense green foliage appears (<a href="#pl4-fig1">Pl. 4, figs. 1</a> and <a href="#pl4-fig2">2</a>).
+Between Juchitán and La Ventosa few trees are more than two
+meters high (<a href="#pl5-fig1">Pl. 5, fig. 1</a>). In many areas the trees and bushes form an
+almost impenetrable tangle, whereas on especially rocky soils or on
+slopes those plants are more widely spaced. Abundant and widespread
+species of trees on the Plains of Tehuantepec include <i>Acacia
+cymbispina</i>, <i>Prosopis chilensis</i>, <i>Caesalpinia coriaria</i>, <i>Caesalpinia
+eriostachys</i>, <i>Celtis iguanaea</i>, <i>Cordia brevispicata</i>, <i>Jatropha
+aconitifolia</i>, and <i>Crescentia alata</i>.</p>
+
+<h4>Montane Vegetation</h4>
+
+<p>In order to illustrate the interruption of subtropical and temperate
+types of vegetation by the lowlands of the Isthmus of Tehuantepec, it
+is necessary to digress for a moment from the isthmus and consider the
+types of vegetation present on the adjacent highlands. On the higher
+peaks, such as Cerro de Zempoaltepetl, above about 2500 meters is fir
+forest (<i>Abies religiosa</i>); lower on the slopes are extensive pine
+forests, which on some slopes are mixed with oak or replaced entirely
+by oaks. Subtropical cloud forest, characterized by relatively cool
+temperatures and high humidity, is found at elevations usually between
+1000 and 1800 meters on the windward slopes of the Sierra Madre
+Oriental in Veracruz and northern Oaxaca and on the northern and
+southern slopes of the Chiapan-Guatemalan Highlands. None of these
+forest types is continuous across the Isthmus of Tehuantepec.</p>
+
+
+<h3><i>The Sierra de los Tuxtlas</i></h3>
+
+<p>Although actually located in the region of the Isthmus of Tehuantepec,
+the Sierra de los Tuxtlas, because of its isolated position, need not
+be considered in great detail in analyzing the distribution of animals
+inhabiting the lowlands of the isthmus. Nevertheless<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span> because some
+species living in the highlands adjacent to the isthmus also live in
+the Tuxtlas, this range is briefly described here. The Sierra de los
+Tuxtlas is a range of volcanos lying near the Gulf Coast in southern
+Veracruz between the mouths of the Río Papaloapan and the Río
+Coatzacoalcos. Volcán San Martín, the highest peak, rises above 1800
+meters. This range of volcanos is surrounded by lowlands, which
+immediately to the south and west are covered with savanna and in
+places by scrub forest. The luxuriant nature of the vegetation on these
+volcanos indicates that this range receives much more rainfall than the
+surrounding lowlands. Especially on the northern slopes, tropical
+rainforest is well developed; this is replaced at about 1200 meters by
+cloud forest. The southern and western slopes are drier, for the lower
+slopes are covered with a scrubby, but evergreen, forest.</p>
+
+<p>Detailed comments on the herpetofauna of the Tuxtlas have been omitted
+purposefully, for the reptiles and amphibians of the region currently
+are being studied by Douglas Robinson.</p>
+
+
+
+
+<h2><a name="GAZETTEER" id="GAZETTEER"></a>GAZETTEER</h2>
+
+
+<p>The following localities are those referred to in the text. The name of
+the locality (listed alphabetically by states) is followed by latitude,
+longitude, elevation, general description (town, ranch, etc.), and
+general type of habitat. Unless otherwise noted, distances are
+straight-line (airline) distances in kilometers. The localities have
+been plotted from the American Geographical Society's "Map of Hispanic
+America on the Scale of 1:1,000,000" (Millionth Map). Numbers in
+brackets identify the position of a locality on the accompanying map
+(<a href="#fig1">Fig. 1</a>).</p>
+
+
+<h3><i>Oaxaca</i></h3>
+
+<div class="blockquot"><p>Agua Caliente.&mdash;Lat. 16° 38'; long. 94° 48'; elev. 140 m. A
+hot spring, 6.9 km. north of La Ventosa on the
+Trans-isthmian Highway; arid scrub forest [43].</p>
+
+<p>Arenal, Cerro de.&mdash;Lat. 16° 18'; long. 95° 32'; elev. 925 m.
+(crest). A ridge northeast of Tenango; scrub forest on
+slopes and pine-oak forest on top [64].</p>
+
+<p>Barrio, El.&mdash;Lat. 16° 38'; long. 95° 07'; elev. 314 m. A
+village about 10 kilometers southwest of Matías Romero;
+transition between scrub forest and broadleaf hardwood
+forest [38].</p>
+
+<p>Bisilana.&mdash;Lat. 16° 20'; long. 95° 13'; elev. 35 m. A place
+name for a former ranch at the edge of Tehuantepec; open
+arid scrub forest [62].</p>
+
+<p>Chivela.&mdash;Lat. 16° 20'; long. 95° 01'; elev. 195 m. A
+village on the Trans-isthmian Railroad, 26 kilometers by
+rail south of Matías Romero and on the western edge of the
+semi-arid Plains of Chivela [40].</p>
+
+<p>Concepción.&mdash;Lat. 16° 17'; long. 95° 29'; elev. 1200 m. A
+ranch on the slopes of Cerro Arenal, east-northeast of
+Tenango; dry pine-oak forest [66].</p><p><span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span></p>
+
+<p>Coyol.&mdash;Exact position unknown; according to Smith and
+Taylor (1950: 10), Coyol is "between San Antonio and Las
+Cruces."</p>
+
+<p>Donají.&mdash;Lat. 17° 13'; long. 95° 02'; elev. 90 m. A village
+at Km. 155 on the Trans-isthmian Highway; rainforest [29].</p>
+
+<p>Escurano.&mdash;Lat. 16° 25'; long. 95° 27'; elev. 500 m. A ranch
+about 25 kilometers west-northwest of Tehuantepec; arid
+scrub forest [51].</p>
+
+<p>Guichicovi, San Juan.&mdash;Lat. 16° 58'; long. 95° 06'; elev.
+250 m. A village on the north slopes of the isthmus, 12
+kilometers north-northwest of Matías Romero; cleared
+hardwood forest and coffee plantations [33].</p>
+
+<p>Huilotepec.&mdash;Lat. 16° 14'; long. 95° 09'; elev. 30 m. A
+small village on the Río Tehuantepec, 13 kilometers
+south-southeast of Tehuantepec; open arid scrub forest [69].</p>
+
+<p>Ixtepec.&mdash;Lat. 16° 34'; long. 95° 06'; elev. 60 m. A town
+and railroad junction on the northwestern edge of the Plains
+of Tehuantepec; arid scrub forest [45].</p>
+
+<p>Juchitán.&mdash;Lat. 16° 26'; long. 95° 02'; elev. 15 m. A town
+on the Plains of Tehuantepec, 22 kilometers by road
+east-northeast of Tehuantepec; arid scrub forest [50].</p>
+
+<p>Limón.&mdash;Lat. 16° 20'; long. 95° 29'; elev. 600 m. A former
+agrarian colony and now a small ranch about 27 kilometers
+west of Tehuantepec; arid scrub forest [60].</p>
+
+<p>Matías Romero.&mdash;Lat. 16° 53'; long. 95° 02'; elev. 200 m. A
+town on the Trans-isthmian Highway and railroad in the hills
+near the crest of the isthmus; broadleaf hardwood forest and
+open pine-oak forest [36].</p>
+
+<p>Mixtequilla.&mdash;Lat. 16° 24'; long. 95° 18'; elev. 40 m. A
+village on the Río Tehuantepec, northwest of Tehuantepec;
+dense scrub forest [57].</p>
+
+<p>Modelo, El.&mdash;Lat. 17° 07'; long. 94° 43'; elev. 200 m. An
+old rubber plantation on the Río Chalchijapa, a tributary to
+the Río Coatzacoalcos; rainforest [31].</p>
+
+<p>Nanches, Portillo Los.&mdash;Lat. 16° 35'; long. 95° 37'; elev.
+500 m. A place name, about 4 kilometers southeast of
+Totolapilla; scrub forest [44].</p>
+
+<p>Nizanda.&mdash;Lat. 16° 42'; long. 95° 02'; elev. 150 m. A
+village on the Trans-isthmian Railroad between Chivela and
+Ixtepec; dense scrub forest [42].</p>
+
+<p>Nueva Raza.&mdash;Exact location unknown; according to Thomas
+MacDougall, this locality is in the lowlands of northern
+Oaxaca; rainforest.</p>
+
+<p>Palmar.&mdash;Lat. 16° 43'; long. 94° 40'; elev. 300 m. A small
+ranch on the west base of Cerro Atravesado; scrub forest
+[39].</p>
+
+<p>Papaloapan.&mdash;Lat. 18° 11'; long. 96° 06'; elev. 25 m. A
+small village on the Río Papaloapan in northern Oaxaca; low
+evergreen forest and savanna [11].</p>
+
+<p>Princesa, La.&mdash;Lat. 16° 56'; long. 95° 02'; elev. 150 m. A
+ranch on the northern slopes of the isthmus, 6 kilometers by
+road north of Matías Romero; poorly developed rainforest
+[34].</p>
+
+<p>Quiengola, Cerro de.&mdash;Lat. 16° 24'; long. 95° 22'; elev. 900
+m. (crest). A hill 15 kilometers west-northwest of
+Tehuantepec; dense scrub forest on slopes and scattered
+pines on top [55].</p>
+
+<p>Salazar.&mdash;Lat. 16° 25'; long. 95° 20'; elev. 45 m. A ranch
+on the Río Tehuantepec, northwest of Tehuantepec; dense
+scrub forest [52].</p>
+
+<p>Salina Cruz.&mdash;Lat. 16° 10'; long. 95° 12'; sea level. A port
+on the Golfo de Tehuantepec; open arid scrub forest [70].
+Collections were made in the vicinity of the town and in the
+open scrub forest 2.4 kilometers north at an elevation of 20
+meters.</p>
+
+<p>San Antonio.&mdash;Lat. 16° 15'; long. 95° 22'; elev. 40 m. A
+ranch about 25 kilometers west-southwest of Tehuantepec;
+arid scrub forest [68].</p>
+
+<p>San Pablo.&mdash;Lat. 16° 24'; long. 95° 18'; elev. 40 m. A ranch
+on the Río Tehuantepec, northwest of Tehuantepec; dense
+scrub forest [56]. Cerro San Pablo probably is the hill
+north of this ranch; this is shown on some maps as Cerro de
+los Amates.</p><p><span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span></p>
+
+<p>San Pedro, Cerro de.&mdash;Lat. 16° 18'; long. 95° 28'; elev.
+about 1100 m. (crest). A ridge about 24 kilometers west of
+Tehuantepec and east of Cerro Arenal; scrub forest on slopes
+and pine-oak forest on top [65].</p>
+
+<p>Santa Efigenia.&mdash;Lat. 16° 25'; long. 94° 13'; elev. 500 m. A
+ranch on the southern slopes of the Sierra Madre de Chiapas,
+8 kilometers north-northwest of Tapanatepec; scrub forest.
+Former home of Francis Sumichrast [53].</p>
+
+<p>Santa Lucía.&mdash;Lat. 16° 18'; long. 95° 28'; elev. 800 m. A
+place name for a former ranch on the east slopes of Cerro
+Arenal; scrub forest [63].</p>
+
+<p>Santa María Chimalapa.&mdash;Lat. 16° 55'; long. 94° 42'; elev.
+296 m. A village on the Río de los Milagros, a tributary to
+the Río Coatzacoalcos; rainforest [35].</p>
+
+<p>Santiago Chivela.&mdash;Lat. 16° 42'; long. 94° 53'; elev. 200 m.
+A village on the Trans-isthmian Highway, 13.4 kilometers by
+road south of Matías Romero; dry, grassy plains and
+scattered clumps of scrubby trees and palms [41].
+Collections were made in the vicinity of the village and at
+a rocky stream, 11 kilometers south on the Trans-isthmian
+Highway at an elevation of 230 m.</p>
+
+<p>Santo Domingo (Petapa).&mdash;Lat. 16° 50'; long. 95° 08'; elev.
+225 m. A village about 13 kilometers west-southwest of
+Matías Romero; semi-arid scrub forest [37].</p>
+
+<p>Sarabia.&mdash;Lat. 17° 04'; long. 95° 02'; elev. 100 m. A
+village 25 kilometers north of Matías Romero on the
+Trans-isthmian Highway; rainforest [32]. Collections were
+made in the vicinity of the village and in the rainforest
+along the Río Sarabia, 5 kilometers north of the village at
+an elevation of 80 meters.</p>
+
+<p>Tapanatepec.&mdash;Lat. 16° 32'; long. 94° 12'; elev. 90 m. A
+town on the Pan-American Highway on the lower slopes of the
+Sierra Madre de Chiapas; dense scrub forest [58].</p>
+
+<p>Tehuantepec.&mdash;Lat. 16° 20'; long. 95° 14'; elev. 35 m. A
+large town on the Plains of Tehuantepec; scrub forest [61].
+Collections were made in the vicinity of the town and in the
+dense scrub forest 8.6 kilometers west at an elevation of 85
+meters and 14 kilometers west at an elevation of 120 meters.</p>
+
+<p>Tenango.&mdash;Lat. 16° 16'; long. 95° 30'; elev. 1100 m. A town
+in the mountains about 40 kilometers west-southwest of
+Tehuantepec; scrub forest [67].</p>
+
+<p>Tequisistlán.&mdash;Lat. 16° 24'; long. 95° 37'; elev. 190 m. A
+village in the valley of the Río Tequisistlán, a tributary
+to the Río Tehuantepec; dense scrub forest [54]. Most
+collections were made about one kilometer north of the
+village where the Pan-American Highway crosses the Río
+Tequisistlán.</p>
+
+<p>Tolosita.&mdash;Lat. 17° 12'; long. 95° 03'; elev. 80 m. A
+village on the Río Tortuguero near the Trans-isthmian
+Highway; rainforest [30].</p>
+
+<p>Tres Cruces.&mdash;Lat. 16° 26'; long. 95° 51'; elev. 750 m. A
+ranch near the Pan-American Highway, 70 kilometers by road
+west-northwest of Tehuantepec; dense scrub forest [49].</p>
+
+<p>Tuxtepec&mdash;Lat. 18° 06'; long. 96° 05'; elev. 80 m. A town on
+the Río Papaloapan in northern Oaxaca; low evergreen forest
+[12].</p>
+
+<p>Ubero.&mdash;Lat. 17° 18'; long. 95° 00'; elev. 80 m. A lumber
+camp and railroad station, 8.5 kilometers south of the Río
+Jaltepec on the Trans-isthmian Highway; rainforest [28].</p>
+
+<p>Unión Hidalgo.&mdash;Lat. 16° 27'; long. 94° 48'; elev. 7 m. A
+village on the railroad, 20 kilometers east-northeast of
+Juchitán; open scrub forest [48].</p>
+
+<p>Ventosa, La.&mdash;Lat. 16° 30'; long. 94° 51'; elev. 25 m. A
+village at the junction of the Pan-American and
+Trans-isthmian highways; open scrub forest [46].</p>
+
+<p>Zanatepec.&mdash;Lat. 16° 28'; long. 94° 22'; elev. 80 m. A
+village on the Pan-American Highway at the eastern edge of
+the Plains of Tehuantepec; dense scrub forest [47]. Most
+collections were made in the scrub forest 5 to 8 kilometers
+west-northwest of the village.</p>
+
+<p>Zarzamora.&mdash;Lat. 16° 21'; long. 95° 48'; elev. 800 m. A
+ranch between La Reforma (16 kilometers west of
+Tequisistlán) and Santa María Ecatepec; scrub forest with
+oaks on higher ridges [59].</p></div><p><span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span></p>
+
+
+<h3><i>Veracruz</i></h3>
+
+<div class="blockquot"><p>Acayucan.&mdash;Lat. 17° 57'; long. 94° 55'; elev. 160 m. A large
+town on the Trans-isthmian Highway; rainforest [21].
+Collections were made in the vicinity of the town, but
+principally at Rancho Las Hojitas, 7 kilometers northwest of
+town at an elevation of 150 meters.</p>
+
+<p>Alvarado.&mdash;Lat. 18° 47'; long. 95° 47'; sea level. A fishing
+village at the mouth of the Río Papaloapan; coastal dunes
+and marshes [1]. Most collections were made 1-3 kilometers
+southeast of the village in marshes on the leeward side of
+the coastal dunes.</p>
+
+<p>Amatitlán.&mdash;Lat. 18° 26'; long. 95° 45'; elev. 4 m. A
+village on the bank of the Río Papaloapan; savanna and sugar
+plantations [6].</p>
+
+<p>Aquilera.&mdash;Lat. 17° 48'; long. 95° 01'; elev. 150 m. A
+village 21 kilometers southwest of Acayucan on the
+Trans-isthmian Highway; rainforest [22].</p>
+
+<p>Ayentes.&mdash;Lat. 18° 10'; long. 94° 26'; elev. 2 m. A railroad
+station on the east bank of the Río Coatzacoalcos, across
+the river from the city of Coatzacoalcos; scrub forest and
+marshes [17].</p>
+
+<p>Berta.&mdash;Lat. 18° 07'; long. 94° 27'; elev. 5 m. A ranch just
+south of Coatzacoalcos; scrub and low evergreen forest [15].</p>
+
+<p>Chacaltianguis.&mdash;Lat. 18° 18'; long. 95° 52'; elev. 5 m. A
+village on the Río Papaloapan; savanna [8].</p>
+
+<p>Ciudad Alemán.&mdash;Lat. 18° 13'; long. 96° 07'; elev. 30 m. A
+new government town, headquarters of the Comisión del
+Papaloapan; scrub and low evergreen forest [10].</p>
+
+<p>Coatzacoalcos (formerly Puerto México).&mdash;Lat. 18° 10'; long.
+94° 27'; elev. 2 m. A seaport at the mouth of the Río
+Coatzacoalcos; scrub on coastal dunes; marshes and low
+evergreen forest inland [16]. Most collections are from the
+forest-savanna ecotone, 8 kilometers southwest of town.</p>
+
+<p>Cosamaloapan.&mdash;Lat. 18° 22'; long. 95° 50'; elev. 4 m. An
+agricultural town on the Río Papaloapan; savanna and sugar
+plantations [7].</p>
+
+<p>Cosoleacaque.&mdash;Lat. 17° 59'; long. 94° 38'; elev. 55 m. A
+village 8 kilometers by road west of Minatitlán; savanna
+[19].</p>
+
+<p>Cuatotolapam.&mdash;Lat. 18° 08'; long. 95° 16'; elev. 13 m. A
+village on the Trans-isthmian Railroad; savanna and low
+evergreen forest along streams [13].</p>
+
+<p>Hueyapan.&mdash;Lat. 18° 08'; long. 19° 09'; elev. 85 m. A town
+32 kilometers by road northwest of Acayucan; savanna and low
+evergreen forest [14]. Collections were made in the vicinity
+of the town and from forest 10 kilometers southeast of town
+at an elevation of 135 meters.</p>
+
+<p>Jesús Carranza (formerly Santa Lucrecia).&mdash;Lat. 17° 27';
+long. 95° 02'; elev. 80 m. A town and railroad junction in
+the middle of the isthmus; rainforest [26]. Most of
+Dalquest's specimens came from varying distances from Jesús
+Carranza along the Río Coatzacoalcos and its tributaries.</p>
+
+<p>Minatitlán.&mdash;Lat. 17° 58'; long. 94° 32'; elev. 15 m. An oil
+refinery center on the Río Coatzacoalcos; savanna [20].</p>
+
+<p>Naranjo.&mdash;Lat. 17° 35'; long. 95° 07'; elev. 100 m. A
+village on the Trans-isthmian Highway, 45 kilometers south
+of Acayucan; rainforest and palm forest [24].</p>
+
+<p>Novillero.&mdash;Lat. 18° 16'; long. 95° 59'; elev. 10 m. A
+village on the Río Papaloapan; scrub forest and grassland
+[9].</p>
+
+<p>Oaxaqueña, La.&mdash;Lat. 17° 26'; long. 94° 53'; elev. 80 m. A
+hacienda on the Río Coatzacoalcos about 12 kilometers east
+of Jesús Carranza; rainforest [27].</p>
+
+<p>Playas, Río de las.&mdash;Lat. 18° 08'; long. 94° 07'; elev. 3 m.
+The river (sometimes known as the Río Tonolá) forming the
+boundary between the states of Veracruz and Tabasco;
+rainforest [18].</p>
+
+<p>San Lorenzo.&mdash;Lat. 17° 44'; long. 94° 42'; elev. 25 m. A
+village on the Río Chiquito, about 30 kilometers southeast
+of Acayucan; rainforest [23].</p><p><span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span></p>
+
+<p>Suchil.&mdash;Lat. 17° 31'; long. 95° 03'; elev. 40 m. A village
+on the Trans-isthmian Railroad, about 10 kilometers north of
+Jesús Carranza; rainforest [25].</p>
+
+<p>Tecolapan.&mdash;Lat. 18° 24'; long. 95° 18'; elev. 275 m. A
+village on a small river of the same name in the western
+foothills of Los Tuxtlas; rainforest [5].</p>
+
+<p>Tejada, Lerdo de.&mdash;Lat. 18° 37'; long. 95° 31'; elev. 60 m.
+An agricultural village, 35 kilometers by road
+east-southeast of Alvarado; scrub forest, marshes, and sugar
+plantations [2]. Collections were made in a marsh, 5
+kilometers west-northwest of the village.</p>
+
+<p>Tlacotalpan.&mdash;Lat. 18° 37'; long. 95° 42'; elev. 3 m. A town
+at the confluence of the Río San Juan and Río Papaloapan;
+marshes and sugar plantations [3].</p>
+
+<p>Tula.&mdash;Lat. 18° 36'; long. 95° 22'; elev. 150 m. A village
+near the western base of Los Tuxtlas; low evergreen forest
+and marshes [4]. Collections were made in a marsh 3
+kilometers northwest of the village.</p></div>
+
+
+
+
+<h2><a name="THE_AMPHIBIAN_FAUNA_OF_THE_LOWLANDS" id="THE_AMPHIBIAN_FAUNA_OF_THE_LOWLANDS"></a>THE AMPHIBIAN FAUNA OF THE LOWLANDS</h2>
+
+
+<p>In presenting an account of the amphibian fauna of the lowlands of the
+Isthmus of Tehuantepec three items must be considered:</p>
+
+<p><span style="margin-left: 2.5em;">1. The composition of the fauna.</span><br />
+
+<span style="margin-left: 2.5em;">2. The ecology of the fauna.</span><br />
+
+<span style="margin-left: 2.5em;">3. The distribution of the fauna.</span><br /></p>
+
+<p>These items, together with similar data concerning the amphibians of
+the adjacent highlands, will form the basis for the subsequent
+discussion of the establishment of present patterns of distribution in
+the isthmian region.</p>
+
+
+<h3><i>Composition of the Fauna</i></h3>
+
+<p>The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 36 species definitely recorded from the area. These include
+one genus and species of caecilian, one genus, including three species
+of salamanders, and 14 genera and 32 species of anurans.</p>
+
+<p>In comparison with the known amphibian fauna of the forested and
+savanna portions of El Petén, Guatemala (Stuart, 1935 and 1958), we
+find that there are more species recorded from the isthmus than from El
+Petén. Stuart found only 20 species of amphibians in both forest and
+savanna habitats in El Petén. Of the 36 species of amphibians known
+from the isthmus, 28 occur on the Gulf lowlands and live in forest or
+savanna habitats.</p>
+
+<p>The geographic position of the isthmus with regard to major faunal
+areas in Middle America, and the diversity of the environment are
+important factors in understanding the presence of a large number of
+species of amphibians in the isthmus. The large number of species
+probably is a reflection of the diversity of the environment; this
+diversity is the result of fluctuation of climate, and thus<span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span>
+environments, in the not too distant past. In no individual habitat,
+such as rainforest, savanna, or scrub forest, does the number of
+species approach the total for the region.</p>
+
+
+<h3><i>Ecology of the Fauna</i></h3>
+
+<p>In the preceding section on the description of the Isthmus of
+Tehuantepec I have outlined the major environments in the region. With
+respect to the distribution of amphibians we may recognize three major
+environments in the isthmus&mdash;rainforest, semi-arid scrub forest, and
+savanna. Each of these has varying combinations of physical and biotic
+factors that are important in the ecology of amphibians. Because of the
+importance of moisture, not only for the maintenance of life in these
+animals, but in most species their dependence on water for breeding
+purposes, this environmental factor is considered the most significant
+in the ecological distribution of amphibians. A second factor is the
+availability of necessary shelter, especially aestivation sites. These
+factors will be compared in the three major environments in the region.</p>
+
+<p>Moisture is present in the environment in the form of free water or
+atmospheric moisture. With respect to the latter, it is well known that
+dense shaded forests have a considerably higher relative humidity than
+do open plains or areas with only scattered trees. Thus, the
+rainforests of the isthmus are characterized by a much higher relative
+humidity than are the savannas or semi-arid scrub forests. Although
+with regard to rainfall there is a pronounced dry season in the regions
+supporting rainforest, there still remains considerable atmospheric
+moisture in this environment throughout the year. The dense foliage
+provides shade and protection from desiccating effects of wind and
+sunlight; furthermore the foliage contributes moisture by
+transpiration. The deep alluvial soils mixed with large quantities of
+organic matter (decaying leaves and rotting logs) maintain considerable
+quantities of moisture.</p>
+
+<p>Conversely, the savannas and scrub forests have little atmospheric
+moisture during the dry season. In the former habitat there are few
+trees to provide shade or moisture through transpiration; in the latter
+most of the trees lose their leaves during the dry season. Thus, these
+environments are desiccated by the dry winds and direct sunlight.
+Furthermore, the soils in these environments become dry and caked.
+There is little or no terrestrial matter to hold moisture.</p>
+
+<p>Free water in these environments is present in a variety of forms<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span> at
+different times of the year. During the dry season the more extensive
+marshes in the savannas persist; many ponds and most of the streams in
+the rainforest are permanent throughout the year. In the scrub forest
+all except the largest streams become dry during the dry season, and no
+ponds exist through the dry season. With the advent of the first heavy
+summer rains the stream beds fill with water, marshes expand, and many
+depressions become ponds (<a href="#pl5-fig2">Pl. 5, fig. 2</a>). At this time the amount of
+free water in the scrub forests and savannas greatly increases, much
+more so than that in the rainforests.</p>
+
+<p>Environments are vertically stratified in the rainforests. There is the
+deep alluvial soil, the ground litter of leaves and decaying logs, the
+low bushes and small trees, and finally the tall trees of the forest.
+Each of these provides certain types of shelter for amphibians. The
+moist soil and litter on the forest floor is an important microhabitat
+for fossorial and strictly terrestrial species. The dense foliage of
+the trees, tree holes, and bromeliads growing on the trees provide
+shelter for arboreal species. Arboreal and terrestrial bromeliads and
+the terrestrial elephant-ear plants (<i>Xanthosoma</i>) contain water in the
+axils of their leaves throughout the year and thus provide an important
+habitat for amphibians. The low, spiny, deciduous trees of the scrub
+forest and the grasses and scattered trees in the savannas provide
+little shelter. In the savannas there are depressions, some of which
+contain water throughout the year; these are often surrounded by trees
+providing refugia for amphibians during the dry season. In the scrub
+forest many species congregate along streams and in moist stream beds
+during the dry season.</p>
+
+<p>Now that the important ecological factors of the major environments
+have been outlined, we may examine the local distribution of amphibians
+in each of these. Beginning with the rainforest, we find only one
+fossorial species, <i>Gymnopis mexicanus</i>. A large number of species are
+found on the forest floor; characteristic inhabitants of the leaf
+litter are: <i>Bufo valliceps</i>, <i>Eleutherodactylus rhodopis</i>,
+<i>Microbatrachylus pygmaeus</i>, and <i>Syrrhophus leprus</i>. Other terrestrial
+amphibians usually are not scattered throughout the rainforest, as are
+those named immediately above, but instead inhabit areas of forest
+adjacent to ponds or streams; these species include: <i>Bufo marinus</i>,
+<i>Eleutherodactylus natator</i>, <i>Eleutherodactylus rugulosus</i>,
+<i>Leptodactylus labialis</i>, <i>Leptodactylus melanonotus</i>, <i>Rana palmipes</i>
+and <i>Rana pipiens</i>. The most striking ecological assemblage<span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span> of
+amphibians in the rainforest is the arboreal group of species,
+including:</p>
+
+<p>
+<span style="margin-left: 2.5em;"><i>Bolitoglossa occidentalis</i></span><br />
+<span style="margin-left: 2.5em;"><i>Bolitoglossa platydactyla</i></span><br />
+<span style="margin-left: 2.5em;"><i>Eleutherodactylus alfredi</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla baudini</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla ebraccata</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla loquax</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla microcephala martini</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla picta</i></span><br />
+<span style="margin-left: 2.5em;"><i>Phrynohyas modesta</i></span><br />
+<span style="margin-left: 2.5em;"><i>Phrynohyas spilomma</i></span><br />
+<span style="margin-left: 2.5em;"><i>Phyllomedusa callidryas taylori</i></span><br />
+</p>
+
+<p>In the savannas <i>Rhinophrynus dorsalis</i>, <i>Engystomops pustulosus</i>, and
+<i>Gastrophryne usta</i> are fossorial species. <i>Bufo marinus</i>,
+<i>Leptodactylus melanonotus</i>, <i>Leptodactylus labialis</i>, <i>Rana palmipes</i>,
+and <i>Rana pipiens</i> are found in the vicinity of permanent water in the
+savannas. Although the savanna habitat does not provide the ecological
+conditions for the existence of an arboreal fauna, many arboreal
+species from the surrounding rainforest utilize the extensive marshes
+and ponds in the savannas for breeding purposes. Thus, <i>Hyla baudini</i>,
+<i>Hyla microcephala martini</i>, <i>Hyla picta</i>, and <i>Phrynohyas spilomma</i>
+have been found breeding in savannas. In parts of savannas where clumps
+of trees surround depressions containing water throughout the year,
+individuals of the species named above, together with <i>Hyla loquax</i> and
+<i>Phyllomedusa callidryas taylori</i>, may not only breed, but remain
+throughout the year.</p>
+
+<p>In the semi-arid scrub forest the same fossorial species as exist in
+the savannas are found. Likewise, <i>Bufo marinus</i>, <i>Leptodactylus
+labialis</i>, <i>Leptodactylus melanonotus</i>, and <i>Rana pipiens</i> are found
+near permanent water. Terrestrial species in this semi-arid environment
+include <i>Bufo canaliferus</i>, <i>Bufo coccifer</i>, <i>Bufo marmoreus</i>,
+<i>Syrrhophus pipilans</i>, and <i>Diaglena reticulata</i>. Of these, <i>Syrrhophus
+pipilans</i> sometimes inhabits low trees and bushes; the others may be
+fossorial. The arboreal species in the scrub forest include <i>Hyla
+baudini</i>, <i>Hyla robertmertensi</i>, <i>Hyla staufferi</i>, and <i>Phyllomedusa
+dacnicolor</i>.</p>
+
+<p><i>Eleutherodactylus rugulosus</i> and <i>Hylella sumichrasti</i> live along
+streams in the scrub forest. <i>Hylella sumichrasti</i> lays its eggs in
+these streams.</p>
+
+<p>In comparing the ecological differences in the amphibian assemblages in
+the three major habitats, the most obvious difference is the great
+percentage of arboreal species in the rainforest as compared with
+savanna and scrub forest. Only four arboreal species are found in the
+scrub forest, none in the savannas, but eleven in the rainforest.
+Likewise, there is an absence of ground-dwelling forms in the arid
+habitats; in the latter the only terrestrial<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span> species are those that
+are found near water. A possible exception is <i>Syrrhophus pipilans</i>.</p>
+
+<p>From the above analysis of ecological distribution we may see that the
+rainforest provides a variety of habitats for amphibians and that these
+habitats are suitable for amphibian life throughout the year. On the
+other hand, the savannas and scrub forests are characterized by extreme
+conditions of desiccation, a factor of considerable importance in
+limiting the ecological distribution of amphibians. However, there
+still is a diversity of amphibians in these semi-arid environments.
+Obviously, these species are adapted in various ways for survival
+during the dry season, at which time environmental conditions are such
+that the animals cannot carry on their normal activities.</p>
+
+<p>Although there is not an abundance of data concerning the seasonal
+activity of the fauna, what is available shows some interesting
+correlations with the environments. During the dry season in the scrub
+forest there is essentially no amphibian activity; an occasional <i>Rana
+pipiens</i> may be seen along a river, or a <i>Bufo marinus</i> may be seen at
+night. In the rainforest the terrestrial-breeding amphibians are active
+during the dry season. <i>Eleutherodactylus rugulosus</i> is found at night
+or by day along streams. <i>Eleutherodactylus rhodopis</i>,
+<i>Microbatrachylus pygmaeus</i>, and <i>Bufo valliceps</i> are active during the
+day; these plus <i>Bolitoglossa occidentalis</i>, <i>Bolitoglossa
+platydactyla</i>, <i>Eleutherodactylus alfredi</i>, <i>Eleutherodactylus
+natator</i>, and an occasional <i>Hyla</i> are active at night.</p>
+
+<p>With the onset of the heavy summer rains and the subsequent formation
+of breeding ponds, amphibian activity reaches a peak. This is
+especially noticeable in the semi-arid environments, where during the
+dry season there is little activity.</p>
+
+<p>Among the anurans in the isthmus the four species of
+<i>Eleutherodactylus</i>, the two species of <i>Syrrhophus</i>, and the one
+species of <i>Microbatrachylus</i> are either known, or presumed, to lay
+eggs on the ground; these develop directly into small frogs. All of the
+other anurans deposit their eggs in water or attach them to objects
+over water (<i>Phyllomedusa</i>); these hatch into tadpoles, which later
+metamorphose into frogs. <i>Hylella sumichrasti</i> is known to breed only
+in streams. All of the other species breed in ponds, but at times some
+species deposit their eggs in streams; in this last group are <i>Bufo
+valliceps</i>, <i>Bufo marmoreus</i>, <i>Phyllomedusa callidryas taylori</i>, and
+<i>Rana pipiens</i>.</p>
+
+<p>Although the ecological data are incomplete, they do show that<span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span>
+ecological conditions differ greatly in the three major environments,
+different species of amphibians inhabit these environments, and that
+the fauna is ecologically diversified in each environment.</p>
+
+
+<h3><i>Distribution of the Fauna</i></h3>
+
+<p>Plotting the distributions of species of amphibians known to live in
+the lowlands of the Isthmus of Tehuantepec results in an array of
+geographic patterns. These may be analyzed with respect to those
+species that are restricted either to the Gulf lowlands or the Pacific
+lowlands, or those that occur on both the Gulf and Pacific lowlands.
+Furthermore, the distributions may be analyzed with respect to those
+species whose ranges extend from México across the Isthmus of
+Tehuantepec into Central America, those that reach the isthmus from
+Central America but do not extend into México proper, and those that
+reach the isthmus from México but do not extend into Central America.
+It should be kept in mind that the following analysis is of the lowland
+inhabitants only. Species inhabiting the foothills and mountains will
+be discussed later.</p>
+
+<p>1. <span class="smcap">Species Restricted to the Gulf Lowlands.</span> Of the 36 species of
+amphibians recorded from the Isthmus of Tehuantepec, nine (25 per cent)
+are in this group. Four of these (<i>Eleutherodactylus alfredi</i>,
+<i>Syrrhophus leprus</i>, <i>Hyla loquax</i>, and <i>Hyla picta</i>) live in the Gulf
+lowlands to the east and to the west of the isthmus. Three others
+(<i>Hyla ebraccata</i>, <i>Hyla microcephala martini</i> and <i>Phyllomedusa
+callidryas taylori</i>) are primarily Central American in their
+distribution and reach the northwestern limits of their ranges in the
+Gulf lowlands of the isthmus, whereas <i>Bolitoglossa platydactyla</i> and
+<i>Eleutherodactylus natator</i> reach the southern limits of their
+distributions in the isthmus.</p>
+
+<p>2. <span class="smcap">Species Restricted to the Pacific Lowlands.</span> This group includes six
+species, or 17 per cent of the amphibian fauna of the isthmus. Two of
+these (<i>Bufo coccifer</i> and <i>Syrrhophus pipilans</i>) range to the east and
+to the west of the isthmus on the Pacific lowlands. Two others (<i>Bufo
+canaliferus</i> and <i>Hyla robertmertensi</i>) range from the isthmus into
+Central America, and <i>Diaglena reticulata</i> and <i>Phyllomedusa
+dacnicolor</i> range on the Pacific lowlands of México southeastward to
+the isthmus.</p>
+
+<p>3. <span class="smcap">Species That Occur on the Pacific and Gulf Lowlands.</span> This group
+includes 19 species, or 53 per cent of the total amphibian fauna. Of
+these, nine species (25 per cent of the entire amphibian<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span> fauna) are
+widespread throughout the lowlands of México and Central America; these
+are:</p>
+
+<p>
+<span style="margin-left: 2.5em;"><i>Gymnopis mexicanus</i></span><br />
+<span style="margin-left: 2.5em;"><i>Rhinophrynus dorsalis</i></span><br />
+<span style="margin-left: 2.5em;"><i>Bufo marinus</i></span><br />
+<span style="margin-left: 2.5em;"><i>Engystomops pustulosus</i></span><br />
+<span style="margin-left: 2.5em;"><i>Leptodactylus labialis</i></span><br />
+<span style="margin-left: 2.5em;"><i>Leptodactylus melanonotus</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla baudini</i></span><br />
+<span style="margin-left: 2.5em;"><i>Hyla staufferi</i></span><br />
+<span style="margin-left: 2.5em;"><i>Rana pipiens</i></span><br />
+</p>
+
+<p>Four species occur on the Gulf lowlands to the east and to the west of
+the isthmus, but on the Pacific lowlands they occur only to the east;
+this group includes <i>Bufo valliceps</i>, <i>Eleutherodactylus rhodopis</i>,
+<i>Phrynohyas modesta</i>, and <i>Phrynohyas spilomma</i>. Three species live to
+the east and to the west of the isthmus on the Pacific lowlands, but
+only to the west on the Gulf lowlands; these include <i>Eleutherodactylus
+rugulosus</i>, <i>Microbatrachylus pygmaeus</i>, and <i>Gastrophryne usta</i>.</p>
+
+<p>Six species that cross the isthmus live on the humid Gulf lowlands and
+on the humid lowlands of Chiapas and Guatemala, but not on the
+semi-arid Plains of Tehuantepec; these include <i>Bolitoglossa
+occidentalis</i>, <i>Eleutherodactylus rhodopis</i>, <i>Microbatrachylus
+pygmaeus</i>, <i>Phrynohyas modesta</i>, <i>Phrynohyas spilomma</i>, and <i>Rana
+palmipes</i>. Of these, <i>Microbatrachylus pygmaeus</i> also occurs in
+scattered humid environments to the west of the isthmus on the Pacific
+lowlands.</p>
+
+<p>Two species are endemic to the isthmian region. <i>Bolitoglossa
+veracrucis</i> is known only from the humid northern slopes of the
+isthmus. <i>Hylella sumichrasti</i> occurs on the Pacific slopes of the
+isthmus and extends to the east into western Chiapas.</p>
+
+<p>In analyzing the distribution of the amphibians with respect to those
+that are restricted to either the Pacific or Gulf lowlands or those
+that cross the continental divide in the isthmus, we find that 25 per
+cent of the species are restricted to the Gulf lowlands, 17 per cent
+are restricted to the Pacific lowlands, and 53 per cent cross the
+isthmus. In analyzing the distribution patterns with respect to those
+that extend across the isthmus of Tehuantepec from east to west, we
+find that 14 per cent of the species do not extend east of the isthmus
+into Central America and that 19 per cent do not range west of the
+isthmus into México proper; 61 per cent of the species range to the
+east and to the west of the isthmus. Of the 36 species of amphibians
+inhabiting the isthmus only nine species (25 per cent) range across the
+isthmus, that is, occur on the Gulf and Pacific lowlands, and also
+range to the east and to the west of the isthmus. To these wide-ranging
+species the diversified environments of the<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span> isthmus do not present a
+barrier to distribution. The other 27 species (75 per cent) either do
+not cross the isthmus from east to west or from north to south; thus,
+probably in one way or another the isthmus presents a barrier to their
+distribution.</p>
+
+
+
+
+<h2><a name="THE_AMPHIBIAN_FAUNA_OF_THE_FOOTHILLS_AND_ADJACENT_HIGHLANDS" id="THE_AMPHIBIAN_FAUNA_OF_THE_FOOTHILLS_AND_ADJACENT_HIGHLANDS"></a>THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS</h2>
+
+
+<p>To amphibians inhabiting the foothills and mountains of southern México
+and northern Central America, the isthmus presents a great barrier to
+dispersal. For example, salamanders of the genus <i>Thorius</i>, the
+<i>mexicanus</i> and <i>augusti</i> groups of the genus <i>Eleutherodactylus</i>, the
+<i>bistincta</i> group of the genus <i>Hyla</i>, and the genus <i>Tomodactylus</i>
+occur on the Mexican Plateau and southward into the mountains of
+Oaxaca. Nevertheless, no members of these groups are present in the
+Guatemalan-Chiapan Highlands. The genera <i>Chiropterotriton</i>,
+<i>Magnadigita</i>, <i>Pseudoeurycea</i>, and <i>Ptychohyla</i>, as well as the
+<i>eximia</i> group of <i>Hyla</i> are represented by different species in the
+Guatemalan-Chiapan Highlands than in the mountains of México on the
+other side of the isthmus. Several species of <i>Plectrohyla</i> occur in
+the Guatemalan-Chiapan Highlands, but none is known from the Mexican
+Highlands, although one species occurs in the Tuxtlas.</p>
+
+<p>Living in the humid forests of the foothills are salamanders of the
+genus <i>Lineatriton</i>, frogs of the <i>spatulatus</i> group of
+<i>Eleutherodactylus</i>, <i>Anotheca coronata</i>, <i>Hyla miotympanum</i>, and
+<i>Phyllomedusa moreleti</i>. All of these occur in the foothills of the
+Sierra Madre Oriental in eastern México and in Los Tuxtlas.
+<i>Lineatriton</i>, <i>Hyla miotympanum</i>, and the <i>spatulatus</i> group of
+<i>Eleutherodactylus</i> do not occur in the foothills of the
+Guatemalan-Chiapan Highlands; those amphibians reach the end of their
+ranges at the isthmus. <i>Phyllomedusa moreleti</i> and <i>Anotheca coronata</i>
+are found in the northern foothills of the Guatemalan-Chiapan
+Highlands, and <i>Phyllomedusa moreleti</i> is found in the foothills on the
+Pacific slopes of the Chiapan Highlands.</p>
+
+<p>Although the above analysis is not so detailed as that of the lowland
+inhabitants, it does show that all of the genera and species of
+amphibians known to inhabit the foothills and highlands adjacent to the
+isthmus, only two species of amphibians cross the isthmus from one
+highland mass to the other. Thus, it is evident that the Isthmus of
+Tehuantepec presents a great barrier to dispersal of these groups of
+amphibians.</p>
+
+
+
+<p><span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span></p>
+<h2><a name="ESTABLISHMENT_OF_PRESENT_PATTERNS_OF_DISTRIBUTION" id="ESTABLISHMENT_OF_PRESENT_PATTERNS_OF_DISTRIBUTION"></a>ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION</h2>
+
+
+<p>From the foregoing analysis of geographical and ecological distribution
+in the Isthmus of Tehuantepec we may strive for an interpretation of
+the events that led to the establishment of patterns of distribution
+displayed not only by the amphibians, but other terrestrial vertebrates
+as well. The thesis that I am proposing below is based on the premise
+that in southern México and northern Central America climatic
+fluctuation during the Pleistocene was of sufficient magnitude to cause
+vegetational shifts, both vertically and latitudinally, resulting in
+the establishment of alternating continuous and discontinuous lowland
+and highland environments, although this climatic fluctuation was not
+so great as to eliminate tropical lowland environments from the region.
+I feel that the present patterns of distribution of the amphibians in
+the Isthmus of Tehuantepec may be explained on this premise.</p>
+
+<p>Many authors dealing with the herpetofauna of Middle America have
+followed Schuchert's (1935) suggestion of a seaway in the isthmus
+during the Cenozoic. Thus, Burt (1931), Duellman (1956, 1958a), Gloyd
+(1940), Oliver (1948), Smith and Laufe (1946), and Stuart (1941)
+employed the presence of a seaway to explain distribution and
+speciation in various genera. Durham, Arellano, and Peck (1952), Olson
+and McGrew (1941), and Stirton (1954) have provided geological evidence
+that there probably was no Cenozoic seaway in the Isthmus of
+Tehuantepec. Even if there were a seaway in the Pliocene or Miocene
+(the dating of this possible seaway is open to question), its presence
+is not necessary to explain the present patterns of distribution in the
+isthmus.</p>
+
+<p>In recent years the study of natural biotic environments, palynology,
+and Pleistocene chronology in Middle America has produced a wealth of
+data, which although still fragmentary begins to form a picture of past
+climatic events in that part of the world. Sedimentary studies by
+Hutchinson, Patrick, and Deevey (1956) and Sears, Foreman, and Clisby
+(1955) have provided evidence of drastic climatic shifts in México
+during the Pleistocene. Further evidence of bioclimatic fluctuation is
+provided by Martin and Harrell (1957) and Martin (1958); the latter has
+suggested that there was a displacement of the tropical zones in
+southern México and northern Central America by as much as 3000 feet
+during the glacial maximum. Much of the evidence of such drastic
+vertical<span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span> shifts in environments is based on the presence of
+Pleistocene montane glaciers on Mexican volcanoes (White, 1956) and
+Chirripo in Costa Rica (Weyl, 1955). Dorf (1959) supports this idea of
+drastic climatic change.</p>
+
+<p>In his studies of the avifauna of México and Guatemala Griscom (1932
+and 1950) made an important issue of the continuity of the bird fauna
+in what he called the Subtropical Life-zone, which essentially consists
+of cloud forest, a widespread, but discontinuous, habitat on the Gulf
+(windward) slopes of the Mexican and Central American highlands at
+elevations between 1000 and 2000 meters. To account for this apparent
+uniformity in the avifauna Griscom hypothesized a continuity of cloud
+forest environment in the Pleistocene; this would result in the
+depression of cloud forests to the coastal lowlands and the
+displacement of tropical lowland environments far to the south in
+Central America. Stuart (1951) objected to this displacement of lowland
+tropical rainforest; he stated that a descent to sea level of a
+subtropical zone would have brought about either widespread
+extermination of the tropical fauna or acclimatization of that fauna to
+subtropical conditions.</p>
+
+<p>Although palynological studies and some faunal studies of subtropical
+and temperate animals suggest a drastic climatic fluctuation that might
+have eliminated tropical environments in southern México and northern
+Central America, there is much biological evidence indicating the
+existence of tropical environments in this region even during the
+glacial maximum. Especially significant is the diversity of species
+inhabiting the present tropical environments; many of these have
+differentiated from related taxa to the south.</p>
+
+<p>In the Pleistocene, climate fluctuated and vegetation shifted
+correspondingly in southern México and northern Central America. Most
+of the palynological studies and many studies of Pleistocene chronology
+deal with montane regions, either the Mexican Plateau or the mountains
+rising from the plateau. No such studies have been made in lowland
+tropical environments. During glacial advances the tropical lowland
+environments in México probably were not eliminated, for the great
+diversity of animals in these environments supports the hypothesis that
+they have been in existence for some time, although periodically they
+may have been discontinuous.</p>
+
+<p>In order to understand the nature of bioclimatological events in the
+Pleistocene in lowland tropical environments of southern México,
+certain factors that are of little importance in the interpretation<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> of
+Pleistocene chronology in the highlands must be considered. These
+factors are: 1) climatic moderation by oceans, 2) fluctuation in sea
+level, and 3) fluctuation in level of the water table as affected by
+sea level.</p>
+
+<p>It is well-known that large bodies of water moderate the temperature on
+adjacent land. Furthermore, it is known that faunas of marine
+invertebrates shifted latitudinally in the Pleistocene; Trask, Phleger,
+and Stetson (1947) recorded cold-water Foraminifera then as far south
+as the Sigsbee Deep in the middle of the Gulf of Mexico. Large bodies
+of warm water, such as the Gulf of Mexico, Caribbean Sea, and Pacific
+Ocean of today, probably were not sufficiently cooled at the time of
+glacial advance to affect greatly the temperature of the winds blowing
+across them. Even if these bodies of water were somewhat cooler than
+now, the prevailing winds blowing from them onto the lowlands of México
+and northern Central America would have aided in maintaining relatively
+high temperatures there. These warm winds probably counteracted the
+cooling effect of glaciation in the lowlands and thereby maintained
+tropical conditions near the seas.</p>
+
+<p>Although no adequate studies of Pleistocene beach lines have been made
+in southern México, such information is available for peninsular
+Florida on the other side of the Gulf of Mexico (Cooke, 1945).
+Fluctuation in sea level in the Pleistocene has been used by Hubbell
+(1954), Goin (1958), and Duellman and Schwartz (1958) to explain
+present patterns of distribution of animals in Florida. If Cooke's
+interpretations can be applied to the western side of the Gulf of
+Mexico, even generally, it would be supposed that sea level varied from
+about 300 feet lower than at present during the Illinoian Glacial
+Period to about 275 feet higher than at present during the Aftonian
+Interglacial Period. Lowering of sea level would expand the lowlands in
+the isthmus; rising sea level would restrict them, leaving only the
+central ridges and many islands in the isthmus, but never forming a
+seaway between the Gulf of Mexico and the Pacific Ocean.</p>
+
+<p>Probably the level of the water table in the coastal lowlands and the
+gradients of the streams in the lowlands and foothills was closely
+correlated with fluctuation in sea level. If sea level fluctuated as
+much as 575 feet in the Pleistocene, changes in the level of the water
+table must have been of considerable magnitude.</p>
+
+<p>During times of glacial advances the lowlands of the isthmus probably
+were more extensive and had more semi-arid tropical<span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span> environments than
+at present, with patches of rainforest existing in sheltered valleys
+along the major streams. In the course of bio-climatic fluctuation the
+semi-arid environments (scrub forest and/or savanna) were continuous at
+times from the Pacific lowlands across the isthmus to the Gulf
+lowlands. At those times such typical inhabitants of the semi-arid
+environments as <i>Rhinophrynus dorsalis</i>, <i>Engystomops pustulosus</i>, and
+<i>Hyla staufferi</i> could have made their way across the isthmus. At times
+of most extensive glaciation, such as the Illinoian, temperatures in
+the isthmus probably were low enough to permit the growth of pine-oak
+forest and cloud forest continuously across the central ridges from the
+Mexican to the Chiapan-Guatemalan highlands. At those times such
+highland members of the fauna as <i>Chiropterotriton</i>, <i>Pseudoeurycea</i>,
+<i>Magnadigita</i>, and the <i>eximia</i> group of <i>Hyla</i> could have crossed the
+isthmus. During Wisconsin time, climate probably fluctuated less than
+during previous glaciations; probably no montane environments, except
+cloud forest, were represented in the isthmus during the Wisconsin.
+Even at this relatively late date such animals as <i>Lineatriton
+lineola</i>, <i>Anotheca coronata</i>, and <i>Phyllomedusa moreleti</i> could have
+crossed the isthmus.</p>
+
+<p>During the interglacial periods, which in the isthmian region were
+characterized by warmer temperatures, higher sea level and consequently
+more restricted areas of lowlands, and possibly more rainfall than in
+the glacial periods, the continuity of pine-oak forest and cloud forest
+from east to west across the isthmus was interrupted. Probably, too,
+the semi-arid environments were restricted, and the rainforests were
+more widespread. At those times animals now inhabiting the rainforests
+of the Gulf lowlands and those inhabiting the Pacific lowlands of
+Chiapas and Guatemala could have crossed the isthmus. In this group are
+species such as <i>Bolitoglossa occidentalis</i>, <i>Eleutherodactylus
+rhodopis</i>, <i>Microbatrachylus pygmaeus</i>, and <i>Rana palmipes</i>.</p>
+
+<p>The amount of differentiation in isolated populations of amphibians in
+southern México and northern Central America gives some idea of
+relative lengths of time of isolation from related populations. Those
+populations inhabiting high mountain environments on either side of the
+isthmus are specifically distinct. Some populations inhabiting cloud
+forests lower on the mountains are specifically distinct from related
+populations on the other side of the isthmus; between others there is
+no recognizable differentiation. Even though many populations are
+isolated from other populations of the same species in the lowlands of
+the isthmus, there is<span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span> no apparent speciation. This indicates that the
+lowland environments and their inhabitants have been isolated from one
+another for a shorter time than have the highland environments and
+their inhabitants.</p>
+
+
+
+
+<h2><a name="ACCOUNTS_OF_SPECIES" id="ACCOUNTS_OF_SPECIES"></a>ACCOUNTS OF SPECIES</h2>
+
+
+<p>For each species of amphibian known to occur in the lowlands of the
+Isthmus of Tehuantepec, localities where one or more specimens were
+collected are listed, and variation, ecology, and life histories are
+discussed. A total of 2833 specimens has been examined for the purposes
+of this study. Individual specimens cited in the text are listed with
+catalogue numbers and abbreviations of the name of the museum, as
+follows:</p>
+
+<p>
+<span style="margin-left: 2.5em;">AMNH&nbsp; American Museum of Natural History</span><br />
+<span style="margin-left: 2.5em;">KU&nbsp; &nbsp; University of Kansas Museum of Natural History</span><br />
+<span style="margin-left: 2.5em;">MCZ&nbsp;  Museum of Comparative Zoology, Harvard College</span><br />
+<span style="margin-left: 2.5em;">UIMNH University of Illinois Museum of Natural History</span><br />
+<span style="margin-left: 2.5em;">UMMZ&nbsp; University of Michigan Museum of Zoology</span><br />
+<span style="margin-left: 2.5em;">USNM&nbsp; United States National Museum</span><br />
+</p>
+
+
+<p class="center"><b>Gymnopis mexicanus mexicanus</b> Duméril and Bibron</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: El Barrio (3); Matías Romero; Tehuantepec (2).
+<i>Veracruz</i>: Cosamaloapan; Cuatotolapam (2).</p></div>
+
+<p>The two specimens from Cuatotolapam were collected by Ruthven in an
+area of mixed savanna and forest. The three specimens (USNM 30535-7)
+listed above from El Barrio were collected by Sumichrast; possibly they
+came from another locality. The city of Tehuantepec is divided into
+seven districts called "barrios." The two specimens listed from
+Tehuantepec (MCZ 1604) merely bear the data "Tehuantepec, Mexico." They
+may have come from the town, the district, or from anywhere in the
+isthmus. The specimen from Matías Romero has 109 primary and 67
+secondary annuli, a length of 400 mm., and a diameter of 19 mm.; the
+one from Cosamaloapan has 106 primary and 58 secondary annuli, a length
+of 397 mm., and a diameter of 19 mm. Data on the other specimens were
+recorded by Dunn (1942:475).</p>
+
+
+<p class="center"><b>Bolitoglossa occidentalis</b> Taylor</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Río Sarabia (2); Ubero. <i>Veracruz</i>: La Oaxaqueña;
+14 km. E of Suchil.</p></div>
+
+<p>The specimens from Oaxaca are only tentatively assigned to
+<i>occidentalis</i>. All are immature and lack maxillary teeth. Taylor
+(1941:147) stated that the maxillary teeth are absent in young
+<i>occidentalis</i>. One from Río Sarabia is a male with a body-length of 29
+mm. and a tail-length of 22 mm. The dorsum is reddish brown<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span> streaked
+with dark gray; the venter is dark gray. Two small individuals (one
+from Sarabia and one from Ubero) have body-lengths of 19 and 21 mm. and
+tail-lengths of 10.5 and 11 mm. In life they were pale yellowish tan
+above with a brown triangular mark on the occiput, but with no
+middorsal stripe. Both were found in the axils of elephant ear plants
+(<i>Xanthosoma</i>).</p>
+
+<p>This species has been noted by Goodnight and Goodnight (1956:146) on
+the Atlantic lowlands at Palenque, Chiapas, and by Shannon and Werler
+(1955:362) at several localities in Los Tuxtlas, Veracruz. I have
+collected it at Vista Hermosa on the eastern slopes of the Sierra Madre
+Oriental above Tuxtepec in northern Oaxaca. Both <i>B. occidentalis</i> and
+<i>B. rufescens</i> have been reported from Palenque, Chiapas (Taylor and
+Smith, 1945:547). Reëxamination of specimens from northern Chiapas and
+Tabasco is needed to verify the sympatric occurrence of these two
+similar species.</p>
+
+
+<p class="center"><b>Bolitoglossa platydactyla</b> Tschudi</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: La Oaxaqueña; Tolosita (2). <i>Veracruz</i>: Acayucan;
+Cuatotolapam; 25 km. ESE of Jesús Carranza; 14 km. E of
+Suchil; 2.7 km. N of Tula.</p></div>
+
+<p>Known only from the Gulf lowlands in the isthmian region, this species
+has been taken in a variety of habitats within the humid forest area:
+under outer leaves of banana plants, under a rock along a stream, under
+a log in a plowed field, and on a reed in a pond at night. Three adult
+males have an average snout-vent length of 44 mm. and a tail-length of
+41 mm. In life the color of the dorsum varied from orange-yellow to
+orange-tan, usually being more orange on the tail. The iris was a
+reddish orange.</p>
+
+
+<p class="center"><b>Bolitoglossa veracrucis</b> Taylor</p>
+
+<div class="blockquot"><p><i>Veracruz</i>: 35 km. SE of Jesús Carranza (21).</p></div>
+
+<p>This species is known only from the type series collected at night on a
+limestone cliff by Walter W. Dalquest. If this salamander is restricted
+to this type of habitat, it should be found in the region of extensive
+limestone outcroppings in northern Chiapas and southern Tabasco.</p>
+
+
+<p class="center"><b>Rhinophrynus dorsalis</b> Duméril and Bibron</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Ixtepec; Limón; Salina Cruz (18); Tehuantepec
+(57); Tuxtepec (3). <i>Veracruz</i>: Amatitlán (3); Cosamaloapan
+(5); Novillero (2); San Lorenzo.</p></div>
+
+<p>This species inhabits the scrub forests of the Pacific coastal plain
+and the savannas in southern Veracruz; apparently it does not occur in
+rainforest. Consequently, its distribution in the isthmus is
+discontinuous.</p>
+
+<p class="center">PLATE 1</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl1-fig1" id="pl1-fig1"></a>
+<img src="images/i_035a.jpg" width="600" height="412" alt="Fig. 1. Savanna about 75 kilometers east of
+Coatzacoalcos, Veracruz. Photograph by L. C. Stuart."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Savanna about 75 kilometers east of
+Coatzacoalcos, Veracruz. Photograph by L. C. Stuart.</span>
+</div>
+<hr class="tb" />
+<div class="figcenter" style="width: 600px;">
+<a name="pl1-fig2" id="pl1-fig2"></a>
+<img src="images/i_035b.jpg" width="600" height="408" alt="Fig. 2. Low scrub forest near Alvarado, Veracruz.
+Photograph by L. C. Stuart."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Low scrub forest near Alvarado, Veracruz.
+Photograph by L. C. Stuart.</span>
+</div>
+<hr class="tb" />
+
+<p class="center">PLATE 2</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl2-fig1" id="pl2-fig1"></a>
+<img src="images/i_036a.jpg" width="600" height="392" alt="Fig. 1. Rainforest near Tolosita, Oaxaca. March, 1956."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Rainforest near Tolosita, Oaxaca. March, 1956.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl2-fig2" id="pl2-fig2"></a>
+<img src="images/i_036b.jpg" width="600" height="396" alt="Fig. 2. Rainforest along the Río Sarabia, Oaxaca. March,
+1956."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Rainforest along the Río Sarabia, Oaxaca. March,
+1956.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 3</p>
+
+<div class="figcenter" style="width: 598px;">
+<a name="pl3-fig1" id="pl3-fig1"></a>
+<img src="images/i_037a.jpg" width="598" height="418" alt="Fig. 1. Transition forest near La Princesa, Oaxaca.
+March, 1956."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Transition forest near La Princesa, Oaxaca.
+March, 1956.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl3-fig2" id="pl3-fig2"></a>
+<img src="images/i_037b.jpg" width="600" height="385" alt="Fig. 2. Palm Savanna on the Plains of Chivela, Oaxaca.
+March, 1956."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Palm Savanna on the Plains of Chivela, Oaxaca.
+March, 1956.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 4</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl4-fig1" id="pl4-fig1"></a>
+<img src="images/i_038a.jpg" width="600" height="392" alt="Fig. 1. Scrub forest on the Plains of Tehuantepec in dry
+season. March, 1956."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Scrub forest on the Plains of Tehuantepec in dry
+season. March, 1956.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl4-fig2" id="pl4-fig2"></a>
+<img src="images/i_038b.jpg" width="600" height="404" alt="Fig. 2. Scrub forest on the Plains of Tehuantepec in
+rainy season. View toward the north. In the distance is the Continental
+Divide in the hills of the Isthmus. July, 1958."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Scrub forest on the Plains of Tehuantepec in
+rainy season. View toward the north. In the distance is the Continental
+Divide in the hills of the Isthmus. July, 1958.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 5</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl5-fig1" id="pl5-fig1"></a>
+<img src="images/i_039a.jpg" width="600" height="411" alt="Fig. 1. Low, dense scrub forest near La Ventosa, Oaxaca.
+July, 1958."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Low, dense scrub forest near La Ventosa, Oaxaca.
+July, 1958.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl5-fig2" id="pl5-fig2"></a>
+<img src="images/i_039b.jpg" width="600" height="424" alt="Fig. 2. Temporary pond in scrub forest north of Salina
+Cruz, Oaxaca. July 7, 1958. Rhinophrynus dorsalis, Bufo marmoreus,
+and Diaglena reticulata were breeding here the previous night."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Temporary pond in scrub forest north of Salina
+Cruz, Oaxaca. July 7, 1958. <i>Rhinophrynus dorsalis</i>, <i>Bufo marmoreus</i>,
+and <i>Diaglena reticulata</i> were breeding here the previous night.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 6</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl6-fig1" id="pl6-fig1"></a>
+<img src="images/i_040a.jpg" width="600" height="392" alt="Fig. 1. Calling male of Rhinophrynus dorsalis,
+photographed in a pond north of Santa Cruz, Oaxaca, on July 6, 1958. ×
+2/3."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Calling male of <i>Rhinophrynus dorsalis</i>,
+photographed in a pond north of Santa Cruz, Oaxaca, on July 6, 1958. ×
+2/3.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl6-fig2" id="pl6-fig2"></a>
+<img src="images/i_040b.jpg" width="600" height="414" alt="Fig. 2. Color pattern variation in two adults of Bufo
+canaliferus from Juchitán, Oaxaca. × 2/3."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Color pattern variation in two adults of <i>Bufo
+canaliferus</i> from Juchitán, Oaxaca. × 2/3.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 7</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl7-fig1" id="pl7-fig1"></a>
+<img src="images/i_041a.jpg" width="600" height="432" alt="Fig. 1. Calling male of Engystomops pustulosus,
+photographed in a pond west of Tehuantepec, Oaxaca, on July 5, 1956. ×
+2."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Calling male of <i>Engystomops pustulosus</i>,
+photographed in a pond west of Tehuantepec, Oaxaca, on July 5, 1956. ×
+2.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl7-fig2" id="pl7-fig2"></a>
+<img src="images/i_041b.jpg" width="600" height="422" alt="Fig. 2. Foamy egg mass of Engystomops pustulosus at
+the edge of a pond west of Tehuantepec, Oaxaca. July 5, 1956. × 3/8."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Foamy egg mass of <i>Engystomops pustulosus</i> at
+the edge of a pond west of Tehuantepec, Oaxaca. July 5, 1956. × 3/8.</span>
+</div>
+
+<hr class="tb" />
+
+<p class="center">PLATE 8</p>
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl8-fig1" id="pl8-fig1"></a>
+<img src="images/i_042a.jpg" width="600" height="417" alt="Fig. 1. Calling male of Diaglena reticulata,
+photographed at a pond north of Salina Cruz, Oaxaca, on July 6, 1958. ×
+1/2."/>
+<span class="caption"><span class="smcap">Fig. 1.</span> Calling male of <i>Diaglena reticulata</i>,
+photographed at a pond north of Salina Cruz, Oaxaca, on July 6, 1958. ×
+1/2.</span>
+</div>
+
+<hr class="tb" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="pl8-fig2" id="pl8-fig2"></a>
+<img src="images/i_042b.jpg" width="600" height="386" alt="Fig. 2. Clasping pair of Diaglena reticulata at the
+edge of a pond north of Salina Cruz, Oaxaca, on July 6, 1958. × 1."/>
+<span class="caption"><span class="smcap">Fig. 2.</span> Clasping pair of <i>Diaglena reticulata</i> at the
+edge of a pond north of Salina Cruz, Oaxaca, on July 6, 1958. × 1.</span>
+</div>
+
+<p><span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span></p>
+
+<hr class="tb" />
+
+<p>Breeding congregations were found after heavy rains at Tehuantepec on
+July 5, 1956, at Cosamaloapan, Novillero, and Amatitlán on July 26,
+1956, and at Salina Cruz on July 6, 1958. The call is a long "worrp"
+made while the male is floating on the surface of the pond. The small
+heads, small limbs, and greatly inflated bodies cause the calling males
+to resemble miniature caricature balloons (<a href="#pl6-fig1">Pl. 6, fig. 1</a>). Amplexus is
+inguinal. These toads are notably wary, even when calling. Often the
+beam of a flashlight or the slightest disturbance of the water will
+cause the males to stop calling. The body is deflated with one last
+nauseous note, and the frog sinks beneath the surface of the water and
+swims away with short slow kicks of the hind feet.</p>
+
+
+<p class="center"><b>Bufo canaliferus</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Chivela; Salina Cruz; Santa Efigenia; Tapanatepec
+(6); Tehuantepec (10); Zanatepec (4).</p></div>
+
+<p>This small toad apparently is restricted to the Pacific lowlands from
+the Isthmus of Tehuantepec eastward to Guatemala. At Zanatepec on July
+13, 1956, males were calling from a flooded field bordered by scrub
+forest. The call is a rather loud nasal racket. Living individuals vary
+greatly in coloration. Some have yellowish tan flanks and dorsum and an
+orange middorsal stripe; others have a pale red dorsum, yellow flanks,
+and a cream middorsal stripe (<a href="#pl6-fig2">Pl. 6, fig. 2</a>).</p>
+
+
+<p class="center"><b>Bufo coccifer</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Juchitán (5); Tehuantepec.</p></div>
+
+<p>It is with some degree of hesitancy that these toads are referred to
+the species <i>coccifer</i>. Although these and other specimens from
+Guerrero and Michoacán display no striking differences from specimens
+from Costa Rica, Nicaragua, and southeastern Guatemala, the ranges of
+the populations are separated by a broad hiatus in Chiapas and
+Guatemala. Possibly this species has utilized the sub-humid corridor
+through northern Central America (Stuart, 1954) and subsequently
+disappeared from the corridor in Guatemala and Chiapas. Specimens of a
+<i>coccifer</i>-like toad collected by Stuart in the vicinity of
+Jacaltenango, Departamento Huehuetenango, Guatemala, are much larger
+than either the Central American or Mexican specimens of <i>coccifer</i>. A
+final commitment on the systematic status must await a thorough study
+of this group of toads.</p>
+
+<p>Males of this species were calling from a grassy rain-pool in open
+scrub forest at the edge of Juchitán on July 6, 1956. The call is a
+low<span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span> "whirrr." The calling males were sitting in the shallow water at
+the edge of pond, where they were hidden by the grass. None was
+observed in open water, as is characteristic of calling males of <i>Bufo
+canaliferus</i> and <i>marmoreus</i>.</p>
+
+
+<p class="center"><b>Bufo marinus</b> Linnaeus</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Agua Caliente; Guichicovi (3); Mixtequilla;
+Tolosita (6); Tehuantepec (37); Tuxtepec; Unión Hidalgo.
+<i>Veracruz</i>: Ciudad Alemán (4); Cosamaloapan; Cuatotolapam
+(19); 20 km. SE of Jesús Carranza (4); 38 km. SE of Jesús
+Carranza (10); 20 km. NE of Jesús Carranza (4); Novillero.</p></div>
+
+<p>This large toad is abundant throughout the lowlands of the isthmus. The
+loud rattling call of males was heard on rainy nights throughout the
+summer. In March, 1956, several adults were found in a small cave back
+of a spring at Agua Caliente.</p>
+
+
+<p class="center"><b>Bufo marmoreus</b> Wiegmann</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Cerro San Pedro (2); Chivela (5); Escurano (3);
+Juchitán; Salina Cruz (101); Santa Lucía (2); 12 km. S of
+Santiago Chivela (11); Santo Domingo; Tapanatepec;
+Tehuantepec (100); Tequisistlán. <i>Veracruz</i>: Alvarado;
+Coatzacoalcos.</p></div>
+
+<p>This toad is abundant on the Pacific lowlands, where it inhabits both
+open and dense scrub forest. On the Gulf lowlands its distribution
+seems to be limited to xeric coastal habitats. Aside from the specimens
+from Alvarado and Coatzacoalcos, it is known in Veracruz only from Boca
+del Río (Langebartel and Smith, 1959:27).</p>
+
+<p>The similarity in size of <i>Bufo marmoreus</i> and <i>valliceps</i> and their
+almost completely allopatric ranges suggest that the two species may be
+in competition at any one locality. Nevertheless, both were calling
+from a small rocky stream south of Santiago Chivela on July 6, 1956.</p>
+
+<p>On the night of July 6, 1958, an estimated 400 toads of this species
+made up a breeding congregation near Salina Cruz. The site was a
+shallow muddy pond about 20 × 40 meters located in an area cleared of
+scrub forest; the banks of the pond were devoid of vegetation (<a href="#pl5-fig2">Pl. 5, fig. 2</a>).
+Breeding in the same pond were <i>Rhinophrynus dorsalis</i> and
+<i>Diaglena reticulata</i>. The following morning no more than a dozen
+<i>Bufo</i> were found in the pond, but several individuals were found
+beneath debris and in small burrows near the pond. On July 7, 1958,
+large numbers of tadpoles and recently metamorphosed young were in a
+shallow grassy pool just east of Salina Cruz.</p>
+
+<p>Taylor (1943b:347) referred certain specimens from Tehuantepec to <i>Bufo
+perplexus</i>, a species closely related to <i>Bufo marmoreus</i>.<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span> Evidence to
+be presented elsewhere shows that <i>perplexus</i> does not occur in the
+isthmus.</p>
+
+
+<p class="center"><b>Bufo valliceps valliceps</b> Wiegmann</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Guichicovi (2); Matías Romero; 32 km. N of Matías
+Romero (2); Nueva Raza; Río Sarabia (3); Santa María
+Chimalapa (14); Santiago Chivela; 12 km. S of Santiago
+Chivela (5); Santo Domingo (5); Tolosita (7). <i>Veracruz</i>:
+Acayucan (3); Alvarado; Amatitlán; Ayentes; Cosamaloapan
+(3); Cosoleacaque (6); Cuatotolapam (14); Hueyapan; 20 km.
+ENE of Jesús Carranza (6); 20 km. S of Jesús Carranza; 25
+km. SE of Jesús Carranza (23); 35 km. SE of Jesús Carranza;
+60 km. SW of Jesús Carranza (5); La Oaxaqueña (4); Novillero
+(4); San Lorenzo (5).</p></div>
+
+<p>Individuals were found in both wet and dry seasons. In the dry season
+they were most frequently found in rainforest, whereas in the rainy
+season breeding congregations were found in savannas as well. This toad
+occurs throughout the Gulf lowlands and on the Pacific slopes and in
+the Grijalva Valley of Chiapas and Guatemala, but not on the Pacific
+lowlands of the isthmus.</p>
+
+<p>I have not been able to recognize individuals referrable to the race
+<i>macrocristatus</i>. Firschein and Smith (1957:219) described
+<i>macrocristatus</i> from the mountains of eastern Oaxaca and referred to
+it specimens from the Gulf lowlands of northern Chiapas. None of the
+present material shows the hypertrophied cranial crests supposedly
+characteristic of <i>macroaristatus</i>, nor do specimens from the isthmus
+resemble the population in the Grijalva Valley being described by L. C.
+Stuart, who will discuss the variation in, and the validity of, the
+named populations of <i>valliceps</i>.</p>
+
+<p>Five specimens from San Lorenzo, Veracruz (USNM 123516-20), were
+identified as <i>Bufo cristatus</i> by Smith (1947:408). Firschein (1950:83)
+redefined the <i>cristatus</i> group of <i>Bufo</i> and assigned these specimens
+to <i>valliceps</i>.</p>
+
+
+<p class="center"><b>Eleutherodactylus alfredi</b> Boulenger</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Tolosita (2). <i>Veracruz</i>: 35 km. SE of Jesús
+Carranza (6).</p></div>
+
+<p>These specimens were collected in rainforest. Shreve (1957:247) pointed
+out the close resemblance between <i>E. alfredi</i> and <i>E. conspicuus</i> from
+Piedras Negras, Guatemala, and treated them as subspecies. Examination
+of the specimens from the isthmus, together with seven from central
+Veracruz and one from Teapa, Tabasco, suggests an even closer
+relationship. <i>Eleutherodactylus conspicuus</i> was diagnosed by Taylor
+and Smith (1945:567) as differing from <i>alfredi</i> "in lacking a tarsal
+fold, in having shorter hind legs with the tibiotarsal articulation
+reaching only to the nostril instead of beyond the tip of the snout;
+the vomerine teeth barely reach the posterior level of the choanae."
+The specimen from<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span> Teapa has the vomerine teeth reaching to the
+posterior edge of the choanae; in the eight specimens from the isthmus
+the teeth reach the posterior edge of the choanae in two and to the
+middle of the choanae in six; in seven specimens from central Veracruz
+the teeth reach the posterior edge of the choanae in two and to the
+middle in five. The tibiotarsal articulation extends beyond the tip of
+the snout in the specimen from Teapa and in two from central Veracruz;
+in three specimens from the isthmus and in one from central Veracruz it
+extends only to the nostril; in the others it extends to the snout. The
+tarsal fold is absent in the specimen from Teapa, in three from the
+isthmus, and in all those from central Veracruz; it is weakly present
+in the others.</p>
+
+<p>In the light of this evidence there seems to be little justification in
+recognizing two species or even two subspecies in this group.
+Consequently, <i>Eleutherodactylus conspicuus</i> Taylor and Smith (1945) is
+here placed in the synonymy of <i>Eleutherodactylus alfredi</i> Boulenger
+(1898), a species with a range extending from Cuautlapan and Potrero
+Viejo in central Veracruz southward and eastward in forested habitats
+to western El Petén, Guatemala.</p>
+
+
+<p class="center"><b>Eleutherodactylus natator</b> Taylor</p>
+
+<div class="blockquot"><p><i>Veracruz</i>: 35 km. SE of Jesús Carranza (3); 38 km. S of
+Jesús Carranza; 55 km. SE of Jesús Carranza.</p></div>
+
+<p>The snout-vent length is 42.0 mm. in a male and averages 59.5 mm. in
+three adult females. The tarsal fold is low and extends about half the
+length of the tarsus; the first and second fingers are subequal in
+length; the tibiotarsal articulation extends beyond the tip of the
+snout. The patches of vomerine teeth lie between the posterior margins
+of the choanae. The throat and belly are immaculate, and the soles of
+the feet are dark. In the isthmus this species can be distinguished
+from <i>Eleutherodactylus rugulosus</i> by less rugose skin on the dorsum
+and absence of dark ventral mottling.</p>
+
+<p>The specimens reported here extend the known range of <i>natator</i>
+eastward from Camotlán, Oaxaca; northward in Veracruz the species
+inhabits foothills as far north as Huatusco.</p>
+
+
+<p class="center"><b>Eleutherodactylus rhodopis</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: 30 km. N of Matías Romero; Río Sarabia (5);
+Tapanatepec (87); Tolosita (6); between Zanatepec and
+Tapanatepec. <i>Veracruz</i>: 25 km. SE of Jesús Carranza; 35 km.
+SE of Jesús Carranza (2); 22 km. SSW of Jesús Carranza; 20
+km. ENE of Jesús Carranza (7); Minatitlán; Tapalapan (5).</p></div>
+
+<p>For the purposes of the present study I am not recognizing
+<i>Eleutherodactylus beati</i>, <i>E. dorsoconcolor</i>, and <i>E. venustus</i> as
+specifically,<span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span> or even subspecifically distinct from the earlier named
+<i>E. rhodopis</i>. Probably these are mere color varieties of a single
+species.</p>
+
+<p>In the dry season frogs of this species were in humid forests, where
+they were most frequently found along small streams and in ravines. The
+species is widespread in the Gulf lowlands, but does not occur on the
+Plains of Tehuantepec. It does inhabit the Pacific slopes on the
+foothills of the Sierra Madre de Chiapas, the western part of which
+extends into eastern Oaxaca near Tapanatepec.</p>
+
+
+<p class="center"><b>Eleutherodactylus rugulosus</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: La Princesa (30); Modelo; Santa Lucía (10);
+Tapanatepec (26); Tehuantepec (6); Tres Cruces (8).
+<i>Veracruz</i>: Tapalapan (5).</p></div>
+
+<p>In addition to the specimens from the lowlands of the isthmus, for the
+purposes of the following discussion, I have included data on two
+specimens from the southern slopes of the Sierra del Sur in Oaxaca
+(Mirador and Chacalapa) and on several specimens from Los Tuxtlas in
+Veracruz (Los Chaneques, 67; Salto de Eyipantla, 35; and San Andrés
+Tuxtla, 11).</p>
+
+<p>Frogs of the <i>Eleutherodactylus rugulosus</i> complex occur from southern
+Veracruz and Sinaloa southward through Central America. Taylor
+(1940:401) described <i>E. vocalis</i> from Hacienda El Sabino, Michoacán;
+Taylor and Smith (1945:580) described <i>E. avocalis</i> from Tres Cruces,
+Oaxaca. These have been considered as species distinct from
+<i>rugulosus</i>, which is known to occur in Veracruz, Guerrero, and Chiapas
+southward into Central America. Although the large number of specimens
+collected in the isthmus does not aid in defining the ranges of the
+taxa involved, these specimens do give some idea of the variation in
+certain characters in a given population.</p>
+
+<p>In specimens from Los Tuxtlas the tarsal fold is well-developed and
+extends two-thirds to three-fourths the length of the tarsus; the
+tibiotarsal articulation reaches the nostril and sometimes slightly
+beyond the tip of the snout. In males the tympanum is nearly equal to
+the diameter of the eye; in females it is about one-half the diameter
+of the eye. The posterior surfaces of the thighs are dark brown or
+black with whitish or cream-colored spots, flecks, or irregular
+mottling. The tarsal fold is dark; the throat is pale in some
+individuals, but in most is mottled with dark brown or gray flecks.
+Individuals from La Princesa near the continental divide in Oaxaca show
+the same variation in body proportions and development of the tarsal
+fold. The posterior surfaces of the thighs are dark brown<span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span> indistinctly
+mottled with lighter brown. The throat is dark brown. Specimens from
+the Pacific slopes of Oaxaca, including the Plains of Tehuantepec, have
+dark brown thighs mottled with dusty cream. The tibiotarsal
+articulation extends slightly beyond the tip of the snout in all
+specimens. In males the tympanum is equal to about two-thirds the
+diameter of the eye. Duellman (1958b:6) discussed the variation in
+these characters in populations in Colima, Jalisco, and Michoacán.</p>
+
+<p>Until the extent of variation of these characters is known throughout
+the range of <i>rugulosus</i>, the recognition of populations either as
+species or subspecies seems superfluous. Consequently, I have used the
+oldest name; this does not necessarily imply, however, that all
+populations of <i>rugulosus</i> (<i>sensu lato</i>) are conspecific.</p>
+
+<p>Of the 200 specimens examined, 15 have a middorsal stripe that is red
+or yellow. The iris varies from a copper to a dark golden color and
+shines bright red at night. Many of the specimens are juveniles; these
+were collected in the dry season, at which time they were found beneath
+rocks along streams, in road culverts where there was some water, and
+in holes in banks and cliffs.</p>
+
+
+<p class="center"><b>Microbatrachylus pygmaeus</b> Taylor</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: La Princesa (5); Matías Romero (9); Río Sarabia
+(41); Tolosita (2). <i>Veracruz</i>: Jesús Carranza; 20 km. ENE
+of Jesús Carranza.</p></div>
+
+<p>The specimens listed above vary widely in color patterns; some of the
+patterns are characteristic of certain named "species": <i>albolabris</i>,
+<i>imitator</i>, <i>lineatissimus</i>, and <i>minimus</i>. The large series from the
+Río Sarabia contains all of the color patterns; this series was
+obtained in one small ravine in the rainforest. At least in the
+isthmian region, this species does not inhabit the Pacific slopes and
+lowlands.</p>
+
+
+<p class="center"><b>Syrrhophus leprus</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: 33 km. N of Matías Romero; Santa Efigenia.
+<i>Veracruz</i>: San Lorenzo.</p></div>
+
+<p>Although the type locality is stated to be Santa Efigenia on the
+Pacific slopes of the Sierra Madre de Chiapas in eastern Oaxaca, the
+type specimen probably came from the northern slopes of the mountains.
+All other known specimens are from the Gulf slopes and lowlands, and
+from several localities in Los Tuxtlas. Details concerning specimens
+from the isthmus and other parts of the range were given by Duellman
+(1958c:8).</p>
+
+<p>Smith (1947:408) reported a specimen of <i>Syrrhophus verruculatus</i>
+Peters from San Lorenzo, Veracruz; he stated that this specimen<span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span> (USNM
+123530) could not be <i>S. leprus</i>, because it had a gray belly, nor <i>S.
+cystignathoides</i>, because of the dark and light dorsal coloration.
+Firschein (1954:57) in his review of the species of <i>Syrrhophus</i> in
+eastern México referred the specimen to <i>S. cystignathoides</i>. The
+specimen is in poor condition. Nevertheless, specific determination is
+possible. Numerous specimens of <i>S. leprus</i> from Los Tuxtlas have gray
+bellies; some have heavier pigmentation than the specimen from San
+Lorenzo. In preservative the dorsum is dark brown with lighter
+mottling. There is little doubt that the specimen from San Lorenzo is a
+<i>Syrrhophus leprus</i>, an abundant and widespread species in the humid
+Gulf lowlands of southern México, and not <i>verruculatus</i>, if this is a
+valid species (see Firschein, <i>op. cit.</i>:58), and not
+<i>cystignathoides</i>, a species known from San Luis Potosí southward to
+central Veracruz.</p>
+
+
+<p class="center"><b>Syrrhophus pipilans pipilans</b> Taylor</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Cerro Arenal; Cerro San Pedro; 6 km. N of Chivela;
+14 km. W of Tehuantepec (2).</p></div>
+
+<p>In the isthmian region this frog is known only from the Pacific slopes
+and the Plains of Tehuantepec. Males call from the ground and from
+trees to heights of about four meters. The call is a single, high, long
+"peep."</p>
+
+
+<p class="center"><b>Engystomops pustulosus</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Chivela; La Ventosa (3); Santo Domingo;
+Tapanatepec (14); Tehuantepec (61); Unión Hidalgo (62).
+<i>Veracruz</i>: Acayucan; Cuatotolapam (7); 10 km. SE of
+Hueyapan (11).</p></div>
+
+<p>Large congregations were breeding at Tehuantepec on July 5, at
+Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs
+were breeding in open ponds in scrub forest and savanna; none was found
+in the rainforest. Males call while floating on the water (<a href="#pl7-fig1">Pl. 7, fig. 1</a>);
+the call is a soft "do-ing, do-ing" with a rising tone on the last
+note. Numerous individual egg masses were along the bank of a pond near
+Tehuantepec; one large composite egg mass there had a surface area of
+about one square meter (<a href="#pl7-fig2">Pl. 7, fig. 2</a>). The large series from Unión
+Hidalgo was obtained by digging specimens out of a dry sandy river bank
+in the dry season. Some of the individuals were buried to a depth of 25
+centimeters.</p>
+
+<p>In life individuals from the Pacific lowlands were dull brown and gray;
+those from Acayucan were dark chocolate brown to black with pink or red
+blotches, forearms, and dorsal stripe. Not all specimens from the
+Atlantic lowlands are so colored; individuals<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span> from Cordoba and
+Mirador, Veracruz, are like those from Tehuantepec.</p>
+
+
+<p class="center"><b>Leptodactylus labialis</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Agua Caliente; Chivela (2); Matías Romero (12); 33
+km. N of Matías Romero (4); Mixtequilla; Santa Efigenia;
+Tapanatepec; Tehuantepec (38); Tolosita (2); 33 km. W of
+Zanatepec (49). <i>Veracruz</i>: Acayucan (3); Ciudad Alemán;
+Cuatotolapam (10); Hueyapan; La Oaxaqueña (4); 38 km. SE of
+Jesús Carranza; 20 km. ENE of Jesús Carranza; Novillero (3);
+San Lorenzo (2).</p></div>
+
+<p>Although <i>Leptodactylus labialis</i> does not appear to be so abundant as
+<i>Leptodactylus melanonotus</i>, the former was found throughout the
+lowlands of the isthmus. In the dry season individuals were found along
+streams, and in the rainy season breeding congregations were found in
+rain pools, marshes, ponds, and even small puddles. The call is a slow
+"wort, wort, wort." Males call beneath the water and from beneath rocks
+and from holes in the ground. The average snout-vent length of eight
+adult males is 37.2 mm. A completely metamorphosed juvenile obtained at
+Hueyapan on July 24, 1956, has a snout-vent length of 11 mm.</p>
+
+
+<p class="center"><b>Leptodactylus melanonotus</b> Hallowell</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Agua Caliente (25); Cerro Arenal (2); Cerro
+Quiengola (3); Cerro San Pedro (3); Chivela (2); Coyol;
+Juchitán; Matías Romero (11); Mixtequilla (2); Papaloapan
+(2); Salazar (9); Salina Cruz; 11 km. S of Santiago Chivela;
+Tapanatepec (17); Tehuantepec (176); Tolosita; Unión
+Hidalgo; 27 km. W of Zanatepec (6). <i>Veracruz</i>: Acayucan;
+Cuatotolapam (9); Cosoleacaque; 20 km. ENE of Jesús Carranza
+(2); 20 km. SE of Minatitlán (2); Novillero; San Lorenzo
+(6).</p></div>
+
+<p>This frog is abundant throughout the lowlands of the isthmus, where in
+the dry season individuals were found along streams and beneath rocks
+at a spring seepage. In the rainy season males were calling from nearly
+every bit of standing water. The call is a soft clicking sound
+resembling that made by striking two small stones together. The average
+snout-vent length of ten adult males is 41.8 mm. There is considerable
+variation in the extent of the yellowish brown glandular areas on the
+belly. Some have none, whereas others have a broad area on the chest, a
+band along the flanks, and a thin band across the lower abdomen.
+Individuals collected in the dry season vary in the same fashion as do
+those collected in the rainy season, at which time they were breeding.
+The glands are equally well-developed in adults of both sexes, and were
+present in some juveniles with snout-vent lengths of less than 20 mm.
+Apparently the development of the glands is not associated with
+maturity, sex, or size.</p><p><span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span></p>
+
+
+<p class="center"><b>Diaglena reticulata</b> Taylor</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Cerro Arenal; Chivela; Salina Cruz (26); San
+Antonio (3); Tehuantepec (2); 8.6 km. W of Tehuantepec (11);
+Zarzamora.</p></div>
+
+<p>Breeding congregations of this rare frog were found 8.6 kilometers west
+of Tehuantepec on July 5, 1956, and at Salina Cruz on July 6, 1958.
+Both choruses took place immediately after torrential rains. In both
+instances the frogs were in and about open muddy pools in the scrub
+forest (<a href="#pl5-fig2">Pl. 5, fig. 2</a>); males called from the bank near the water, and
+clasping pairs were found only on land (<a href="#pl8-fig1">Pl. 8, figs. 1</a>-<a href="#pl8-fig2">2</a>). The call is
+a loud, nasal "braaa," two to three seconds in duration. Amplexus is
+axillary.</p>
+
+<p>The dorsal ground color is light yellowish green tending towards olive
+on the head and fading to yellow on the flanks. The ventral surfaces,
+including the vocal sac, are white; the iris is golden and flecked with
+black. The present series agrees well with the description of
+<i>reticulata</i> (based on two specimens) given by Taylor (1942:60). A
+detailed analysis of variation, comparison with related species, and
+descriptions of tadpoles are reserved for a future report.</p>
+
+
+<p class="center"><b>Hyla baudini</b> Duméril and Bibron</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Bisilana; Cerro Quiengola (2); Cerro San Pedro;
+Coyol; Matías Romero (12); Mixtequilla; Río Sarabia (7);
+Salazar; San Antonio; 11 km. S of Santiago Chivela; Santo
+Domingo (3); Tapanatepec (2); Tehuantepec (23); Tolosita.
+<i>Veracruz</i>: Acayucan; Amatitlán; Ciudad Alemán (3);
+Cosamaloapan (2); Cuatotolapam (15); 10 km. SE of Hueyapan;
+20 km. S of Jesús Carranza; 38 km. S of Jesús Carranza (2);
+20 km. ENE of Jesús Carranza (4); La Oaxaqueña (2);
+Minatitlán (2); Naranja (3); Novillero (9); Río de las
+Playas (2); San Lorenzo (5); Tapalapan (2).</p></div>
+
+<p>Commonly found on both sides of the isthmus, this large tree frog
+nearly always is associated with trees; it is not found in the
+savannas, although it breeds in savannas adjacent to rainforest. It
+appears to be somewhat more abundant in scrub forest than in
+rainforest. In the daytime individuals were found under the outer
+sheaths of banana plants, in the axils of leaves of elephant ears
+(<i>Xanthosoma</i>), in cavities in trees, and on shaded limbs in the
+forest. Recently metamorphosed individuals having snout-vent lengths
+slightly more than 20 mm. were found in the latter part of July.</p>
+
+
+<p class="center"><b>Hyla ebraccata</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Donají (17); 43 km. N of Matías Romero (27);
+Sarabia (6); Tolosita (3); Ubero (17). <i>Veracruz</i>: Aquilera.</p></div>
+
+<p>This small species was found only in forested areas, where calling
+males were on bushes and trees around rain pools. The call<span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span> is a harsh
+squawk repeated at intervals of 15 to 20 seconds, followed by a minute
+or more of silence, and then repeated. Clasping pairs were found on
+bushes and in the water.</p>
+
+<p>The dorsum bears a dark chocolate brown hour glass-shaped mark, which
+in some individuals is broken into a large mark posteriorly and a
+smaller triangular one on the head and nape. The dorsal ground color
+varies from pale cream or ivory to yellow or tan. The intensity of the
+dorsal pigmentation is subject to rather rapid change. The flanks,
+hands, and anterior part of the venter are lemon yellow; the feet,
+thighs, and posterior part of the venter are golden yellow. The dorsal
+surface of the shank is yellow to tan with chocolate brown bars or
+spots; the heel is pale yellow. There is a dark brown bar in the loreal
+region and a dark brown bar extending posteriorly from the eye to a
+point above the insertion of the forelimb. The iris is a copper color.
+The toes are completely webbed; the fingers, one-third webbed. There is
+a small axillary web that is evident when the forelimbs are at right
+angles to the body. Twenty males have an average snout-vent length of
+28.1 mm.; three females, 35.3 mm. There are no nuptial tuberosities on
+the pollex of breeding males.</p>
+
+<p>This species has been collected at Coyame and Catemaco in Los Tuxtlas
+and at various localities in Tabasco; it apparently ranges eastward
+from southern Veracruz, México, in humid forests to El Petén,
+Guatemala.</p>
+
+
+<p class="center"><b>Hyla loquax</b> Gaige and Stuart</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Donají (7); 43 km. N of Matías Romero (21).
+<i>Veracruz</i>: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW
+of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San
+Lorenzo (8).</p></div>
+
+<p>In the isthmus this species is known only from the humid forests of the
+Gulf lowlands; it is also known from Boca del Río, Veracruz, and from
+Teapa and Villa Hermosa, Tabasco.</p>
+
+<p>Calling males were found on aquatic plants above the water in deep
+ponds in the forest where it was necessary for the collector to wade
+waist-deep in water to obtain them. The call is a loud "hah-onk."
+Individuals, when active at night, are yellowish tan above with light
+olive green spots. The flanks, belly, and vocal sac are yellow, and the
+anterior and posterior surfaces of the thighs and webbing of the feet
+are bright orange-red or tomato red. Individuals found during the day
+are grayish brown with olive markings or reddish brown with black
+markings. Sleeping individuals are ivory-gray with faint gray markings.
+The iris is a bright copper color. Fifteen adult males have an average
+snout-vent length of<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> 41.7 mm.; they have no horny nuptial pads on the
+pollex.</p>
+
+<p>The relationships of this species are with <i>Hyla rickardsi</i> Taylor, a
+species known only from the foothills of the Sierra Madre Oriental in
+the states of Puebla and Veracruz. The distinguishing characteristics
+of these species are given in Table 1. Living individuals may be
+distinguished immediately by the flash colors on the thighs&mdash;red in
+<i>loquax</i> and yellow in <i>rickardsi</i>. The calls of the two species are
+distinctly different; that of <i>rickardsi</i> is a high-pitched, loud
+rattle continued for several seconds, notably different from the
+goose-like honk of <i>loquax</i>.</p>
+
+<p class="center"><span class="smcap">Table 1.&mdash;Comparison of Certain Characters in Hyla loquax and Hyla rickardsi</span></p>
+
+
+<div class="center">
+<table border="1" cellpadding="6" cellspacing="0" summary="table1">
+<tr><th align="center"><span class="smcap">Character</span></th><th align="center"><i>loquax</i></th><th align="center"><i>rickardsi</i></th></tr>
+<tr><td align="left">Toe webbing</td><td align="left">Full</td><td align="left">Three-fourths</td></tr>
+<tr><td align="left">Finger webbing</td><td align="left">Three-fourths</td><td align="left">One-half</td></tr>
+<tr><td align="left">Average snout-vent length (&#9794;)</td><td align="left">41.7 mm.</td><td align="left">37.4 mm.</td></tr>
+<tr><td align="left">Tympanum/eye (&#9794;)</td><td align="left">63.2%</td><td align="left">55.8%</td></tr>
+<tr><td align="left">Dorsal leg pattern</td><td align="left">Barred</td><td align="left">Unmarked</td></tr>
+<tr><td align="left">Tarsal fold</td><td align="left">Tubercular</td><td align="left">Absent</td></tr>
+<tr><td align="left">Tarsal stripe</td><td align="left">Absent or indistinct</td><td align="left">Broad, indistinct, or absent</td></tr>
+<tr><td align="left">Dorsolateral stripe</td><td align="left">Absent</td><td align="left">Present</td></tr>
+<tr><td align="left">Light line over anus</td><td align="left">Broad</td><td align="left">Narrow</td></tr>
+<tr><td align="left">Flash colors</td><td align="left">Red</td><td align="left">Yellow</td></tr>
+<tr><td align="left">Iris color</td><td align="left">Copper</td><td align="left">Bronze</td></tr>
+</table></div>
+
+<p>The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were
+identified as <i>Hyla rickardsi</i> by Smith (1947:409). The flash colors
+have faded in preservative, and so are of no aid in identifying these
+specimens. Two are adult females with snout-vent lengths of 35 and 39
+mm. In possessing a relatively large tympanum and barred thighs, and in
+lacking a dorsolateral stripe they are typical of <i>loquax</i>, but in the
+amount of webbing on the hands and feet, broad tarsal stripe, and
+narrow anal stripe they are like <i>rickardsi</i>. The third specimen, a
+juvenile, has a snout-vent length of 25 mm. In coloration it resembles
+the adults; it has more distinct<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span> bars on the limbs. On the basis of
+geography these specimens should be <i>loquax</i>, for the closest known
+record of <i>rickardsi</i> is more than 200 kilometers to the northwest,
+whereas <i>loquax</i> is known from several localities around San Lorenzo.</p>
+
+<p>Shannon and Werler (1955:383) described <i>Hyla axillamembrana</i> from the
+lower southern slopes of Los Tuxtlas. The unique type is a small male
+(27 mm. snout-vent). I have examined the type and find no great
+differences between it and small specimens of <i>loquax</i>. It is not
+possible to determine the color of the thighs, nor was this information
+given in the description. <i>Hyla axillamembrana</i> is here considered to
+be a synonym of <i>Hyla loquax</i>.</p>
+
+
+<p class="center"><b>Hyla microcephala martini</b> Smith</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Donají (15); 43 km. N of Matías Romero (19); Río
+Sarabia (2); Sarabia (11); Tolosita. <i>Veracruz</i>: Acayucan
+(17); Alvarado (41); Aquilera (21); 8 km. SW of
+Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of
+Hueyapan; Naranja (3); Novillero.</p></div>
+
+<p>This frog is abundant in the Gulf lowlands of the isthmus, where large
+breeding congregations were found in grassy ponds on the savannas and
+in openings in the forest. Most frequently males were calling from
+grasses and reeds in the ponds; many individuals were perched
+precariously on thin blades as high as one meter above the water. The
+call is a series of low squeaks.</p>
+
+<p>Individuals found at night were pale yellow above with light brown
+lines arranged in an irregular pattern on the back, but often forming a
+cross or an X-shaped mark in the scapular region. There is a brown
+stripe from the nostril to the eye and thence to the groin. Anteriorly
+this stripe is bordered above by a thin white or cream-colored line.
+Numerous small brown flecks are scattered on the back and dorsal
+surface of the shank. In most specimens there are thin transverse brown
+bars on the shank. The thighs and undersides of the limbs are golden
+yellow; the belly and vocal sac are lemon yellow. The iris is yellowish
+brown. During the day individuals assume a pale reddish tan ground
+color with darker brown markings. Twenty-five adult males from Alvarado
+have an average snout-vent length of 24.1 mm.</p>
+
+
+<p class="center"><b>Hyla picta</b> Günther</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Donají (8); Sarabia (11); Tolosita (15); Ubero
+(6). <i>Veracruz</i>: 19 km. N of Acayucan (4); Alvarado (5);
+Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan
+(7); Lerdo de Tejada; Tula (3).</p></div>
+
+<p>Widespread in the forests, scrub, and savannas on the Gulf lowlands of
+the isthmus, these frogs were found breeding at numerous localities.
+Males call from grasses and bushes growing in and<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span> about ponds. The
+call is a high-pitched insect-like trill. At night these frogs are pale
+yellow above; they change to light grayish tan during the day. A dark
+stripe extends from the nostril to the eye and thence posteriorly to a
+point between the axilla and groin. Above this dark stripe is a broader
+white stripe. Scattered on the dorsum are brown flecks or spots; the
+shanks are marked with poorly-defined cross-bars. The thighs are deep
+yellow below and paler above with scattered dark flecks. The belly is
+white, and the vocal sac is yellow. The iris is golden. Twenty males
+have an average snout-vent length of 21.5 mm.; three females, 24.0 mm.</p>
+
+
+<p class="center"><b>Hyla robertmertensi</b> Taylor</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38);
+7.2 km. WNW of Zanatepec (77).</p></div>
+
+<p>This species was found in the isthmian region only on the Pacific
+lowlands at the southern base of the western part of the Sierra Madre
+de Chiapas. On July 13, 1956, many large choruses were discovered. The
+calling males were on reeds and thorn scrub in and at the edge of
+temporary ponds; the call is a cricket-like "creak-creack," quickly
+followed by a series of notes "creak-eek-eek-eek-eek."</p>
+
+<p>At night the dorsal ground color is pale yellow; this changes to
+pinkish buff during the day. There is a grayish or brown dark stripe
+from the nostril to the eye; the stripe continues to the groin. This
+dark stripe is bordered above by a narrow white stripe. The belly is
+white, and the vocal sac is yellow. The iris is dull reddish brown.
+Twenty-five males have an average snout-vent length of 24.7 mm.</p>
+
+
+<p class="center"><b>Hyla staufferi</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Chivela; Huilotepec (5); Juchitán (4); Matías
+Romero (4); 25 km. N of Matías Romero; Mixtequilla (4); Río
+Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3);
+Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero;
+Unión Hidalgo; Zanatepec (6). <i>Veracruz</i>: Acayucan (7);
+Alvarado (3); Amatitlán; Aquilera; Ciudad Alemán (3); 8 km.
+SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8);
+10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula
+(2).</p></div>
+
+<p>This is the only species of small hylid that crosses the isthmus.
+Calling males were found in and about ponds on the savannas in southern
+Veracruz, in ponds in open forest in northern Oaxaca (not in forest
+pools), and in temporary pools in the scrub forest on the Pacific
+lowlands. Individuals usually called from bushes and reeds in or at the
+edge of ponds. The call is a short "braaa." Dates of breeding choruses
+indicate that by the time the other small species of hylids in the Gulf
+lowlands reach the peak of their<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span> breeding season, that of <i>H.
+staufferi</i> is essentially over; no large breeding congregations were
+found in July. On July 8, 1956, two metamorphosing young were found
+clinging to blades of grass in a pond; they had snout-vent lengths of 8
+and 9 mm. and tail stumps less than 3 mm. in length. Others were found
+on July 13 and 26. The juveniles are nearly unicolor olive green above
+and white below.</p>
+
+<p>In life the adults vary greatly in color pattern. The dorsal ground
+color is yellowish tan to olive brown with olive brown or dark brown
+spots, some of which in certain individuals are connected to form
+longitudinal dark stripes. On the posterior surface of the thighs are
+small white flecks. The belly is white, and the vocal sac is a rich
+yellow. Twenty males have an average snout-vent length of 26.3 mm.;
+they have no horny nuptial pads. No noticeable differences in either
+color or body proportions were found between the populations on either
+side of the isthmus.</p>
+
+
+<p class="center"><b>Hylella sumichrasti</b> Brocchi</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Cerro Arenal (5); Cerro San Pedro (2); Escurano;
+La Concepción (41); Portillo Los Nanches (6); San Antonio
+(16); 11 km. S of Santiago Chivela (18); Santa Lucía (7);
+Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces
+(19).</p></div>
+
+<p>With the exception of the series from 11 kilometers south of Santiago
+Chivela, most of these specimens were found in small arboreal
+bromeliads during the dry season. Males were found along a clear,
+shallow, rocky stream south of Santiago Chivela on July 6, 1956. The
+frogs were calling from bushes and rocks in and along the stream. When
+disturbed, they jumped into the water and floated downstream until they
+were able to hold onto a rock or other object. The call is a loud
+"bra-a-ah." In breeding individuals the dorsum is pale yellow; the
+belly is white, and the vocal sac is yellow. The iris is pale golden
+yellow. Eighteen males have an average snout-vent length of 25.2 mm.
+All have dark brown nuptial tuberosities on the pollex.</p>
+
+<p>Certain diagnostic characters of this species as given by Taylor
+(1943a:50) and Taylor and Smith (1945:598) are in need of revision.
+<i>Hylella sumichrasti</i> has been characterized as having no vocal sac,
+rarely having vomerine teeth, and as having a relatively smooth throat.
+The vocal sac in breeding males is quite evident; it is single, median,
+and when expanded, spherical. The openings into the vocal sac are
+narrow slits along the inner posterior border of the jaw rami. Of 151
+specimens studied, 74 have vomerine<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span> ridges between the choanae, and 36
+of these have one to three teeth on each ridge. The belly and
+undersurfaces of the thighs are granular; the throat is only somewhat
+less so. The granular condition may be correlated with breeding, for
+specimens obtained from bromeliads in the dry season had rather smooth
+throats. It seems that the vocal sac atrophys in the non-breeding
+season. These seasonal changes may account for the diagnoses given by
+Taylor (<i>op. cit.</i>) and Taylor and Smith (<i>op. cit.</i>); likewise, since
+many of the specimens obtained by Smith in the dry season were
+juveniles and subadults, the development of the vomerine ridges could
+not be diagnosed properly.</p>
+
+<p>The range of this species encompasses the Pacific slopes of the Isthmus
+of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of
+Tonalá in western Chiapas. Priscilla Starrett collected tadpoles of <i>H.
+sumichrasti</i> from a stream 19 km. N of Arriaga, Chiapas. These limited
+observations on the ecology of this frog suggest that it breeds in the
+fast-moving streams of the Pacific slopes, and that it seeks shelter in
+arboreal bromeliads during the dry season.</p>
+
+
+<p class="center"><b>Phrynohyas modesta</b> Taylor and Smith</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Tuxtepec. <i>Veracruz</i>: 20 km. S of Jesús Carranza;
+20 km. ENE of Jesús Carranza (2); Minatitlán.</p></div>
+
+<p>I have not collected this species in the isthmus. The locality records
+indicate that the range is discontinuous (Duellman, 1956:27). The
+species occurs on the humid Pacific slopes from south-central Chiapas
+eastward to El Salvador and on the humid Gulf lowlands from southern
+Veracruz eastward into Tabasco, but is unknown from the dry Pacific
+slopes and plains in the isthmus.</p>
+
+<p>The acquisition of several specimens of this species in southern
+Veracruz, Tabasco, and Oaxaca, together with a knowledge of the
+variation displayed by <i>Phrynohyas spilomma</i>, suggests that <i>modesta</i>
+may be a color variety of <i>spilomma</i>.</p>
+
+
+<p class="center"><b>Phrynohyas spilomma</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Tapanatepec (3). <i>Veracruz</i>: Amatitlán (12);
+Chacaltianguis (2); Ciudad Alemán (6); Cosamaloapan;
+Novillero (3).</p></div>
+
+<p>Like the preceding species, this frog is unknown from the arid Pacific
+lowlands of the isthmus; its presence at Tapanatepec, a locality
+situated in more mesic conditions than prevail on the Plains of
+Tehuantepec, indicates that it may have a distribution on the Pacific
+slopes much like that of <i>P. modesta</i>. Furthermore, this frog<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span> was not
+detected in the rainforests of the Gulf lowlands; in that region it was
+found only in scrub forest and savanna.</p>
+
+<p>On July 26, 1956, numerous choruses of these frogs were heard between
+Ciudad Alemán and Tlacotalpan, Veracruz. The call is a loud, nasal
+"grawl" repeated continuously. The males call from the water. Several
+clasping pairs were found in shallow grassy ponds amidst the scrub
+forest. The ground color varies from reddish brown to tan with dark
+brown dorsal markings. The iris is golden, and the vocal sacs are dark
+olive brown. After a light shower during the dry season, six
+individuals were found on the low branches of trees at night near
+Ciudad Alemán.</p>
+
+
+<p class="center"><b>Phyllomedusa callidryas taylori</b> Funkhouser</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Donají (9); Sarabia (8); Tolosita (6); Ubero (27).
+<i>Veracruz</i>: Alvarado (7); Aquilera; Berta; Coatzacoalcos
+(9); 10 km. SE of Hueyapan (5); Naranja (17).</p></div>
+
+<p>In life this frog presents a striking array of colors. The dorsum
+varies from pale green to dark olive green; there may be scattered
+whitish or cream-colored spots on the back. On the flanks are bright
+yellow to deep cream-colored vertical bars separated by pale blue or
+purple interspaces. The thighs and undersurfaces of the hind limbs are
+golden orange; the belly is yellow, and the throat is cream-colored.
+The iris is crimson; the transparent part of the lower eyelid has
+golden reticulations. When the frog is resting, the forefeet are folded
+beneath the throat, and the limbs are folded tightly against the body.
+In this position and with the eyes closed and head flattened, this
+gaudy frog assumes the appearance of a small elliptical green leaf.</p>
+
+<p>Throughout the month of July, 1956, <i>Phyllomedusa</i> was breeding in
+ponds in or adjacent to the rainforest in northern Oaxaca and in
+southern Veracruz. Only at Alvarado was it found breeding in a grassy
+pond. Males and females alike were found on bushes and trees in and
+around the ponds. The call is a single "wank." Amplexing males continue
+to call, but the call is softer and less nasal in quality. The eggs are
+encased in pale green gelatin and attached to leaves on branches
+overhanging the water. Three egg clutches contained 38, 41, and 46
+eggs.</p>
+
+
+<p class="center"><b>Phyllomedusa dacnicolor</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Escurano; Tehuantepec.</p></div>
+
+<p>Although it is abundant on the Pacific lowlands to the northwest in
+Guerrero, Michoacán, and Colima, this species is known only from two
+specimens from Tehuantepec. There is no apparent<span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span> physical barrier to
+their distribution in the isthmus; in the Balsas Basin the species
+lives in a hotter, more arid environment than that at Tehuantepec.</p>
+
+
+<p class="center"><b>Gastrophryne usta</b> Cope</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Santa Efigenia; Tehuantepec (10); 24 km. W of
+Tehuantepec; Tolosita (2). <i>Veracruz</i>: Ayentes (6); La
+Oaxaqueña; Novillero (2); San Lorenzo.</p></div>
+
+<p>Calling males were found in open scrub forest near Tehuantepec and in
+savannas near Novillero. The specimens from Tolosita were found under
+cover in a clearing in the forest (Fugler and Webb, 1957:106).</p>
+
+<p>Specimens from the Pacific lowlands are typical of <i>Gastrophryne usta
+gadowi</i> Boulenger in possessing a thin line on the posterior surface of
+the thighs and a thin line from the snout to the vent. Of nine
+specimens from the Gulf lowlands (Ayentes, Novillero, and San Lorenzo),
+seven have a middorsal line; this is narrow in four and wide in three.
+Five have the stripes on the thighs. Two specimens from the middle of
+the isthmus (Tolosita) have no stripes on the thighs; one has a thin
+middorsal line, and the other has a broad line. The adult males have a
+black throat; females have a mottled one. The brown reticulations on
+the bellies of specimens from the Gulf lowlands is bolder than on
+specimens from the Pacific lowlands. The presence of certain characters
+supposedly diagnostic of the subspecies <i>gadowi</i> (line on dorsum and
+thighs) in the population of <i>usta</i> in southern Veracruz suggests that
+a redefinition of the ranges of these subspecies will be in order when
+sufficient material is available to delimit them accurately. For the
+present I prefer to consider all specimens from the isthmus solely as
+<i>Gastrophryne usta</i> without referring them to subspecies.</p>
+
+
+<p class="center"><b>Rana palmipes</b> Spix</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Matías Romero (11); 11 km. S of Santiago Chivela;
+Santo Domingo; Sarabia. <i>Veracruz</i>: Coatzacoalcos;
+Cuatotolapam; 25 km. SE of Jesús Carranza (4); Tlacotalpan
+(2); Tula.</p></div>
+
+<p>Adults were found along streams and in marshes in savannas and
+rainforest. These frogs are wary and difficult to capture, even at
+night. <i>Rana palmipes</i> is another species that has a discontinuous
+distribution in the isthmus. The species does not occur on the Pacific
+lowlands of the isthmus, but does occur on the more humid Pacific
+slopes of Chiapas and Guatemala.</p>
+
+<p>Tadpoles were found in a small sluggish tributary to the Río Sarabia.</p><p><span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span></p>
+
+
+<p class="center"><b>Rana pipiens</b> Schreber</p>
+
+<div class="blockquot"><p><i>Oaxaca</i>: Agua Caliente; Cerro Quiengola; Escurano (14); Río
+Sarabia (2); Tapanatepec (5); Tehuantepec (24). <i>Veracruz</i>:
+Acayucan; Cuatotolapam (15); Jesús Carranza (2); 20 km. S of
+Jesús Carranza (11); 25 km. SE of Jesús Carranza; 20 km. ENE
+of Jesús Carranza (10); San Lorenzo (10).</p></div>
+
+<p>As in most other places in México and northern Central America, this
+species occurs wherever there is permanent water. Males were heard
+calling from woodland ponds and from savanna ponds.</p>
+
+
+
+
+<h2><a name="SUMMARY" id="SUMMARY"></a>SUMMARY</h2>
+
+
+<p>Investigations of the amphibians and their environments in the Isthmus
+of Tehuantepec have been presented with the aim of gaining an
+understanding of the present biological and of the historical events
+responsible for the present patterns of distribution of amphibians in
+this region.</p>
+
+<p>The Isthmus of Tehuantepec embraces three major environments&mdash;savanna,
+semi-arid scrub forest, and quasi-rainforest. The rainforest presents
+an environment noticeably different from the other two and has a
+different amphibian fauna.</p>
+
+<p>Analysis of present patterns of distribution shows that certain species
+are restricted to the rainforests on the Gulf lowlands; others live
+only in the semi-arid scrub forests on the Pacific lowlands. A third
+group of species lives on both the Gulf and Pacific lowlands; most of
+these species occur only in the scrub forests or savannas on the Gulf
+lowlands, but some also inhabit the rainforest. In one way or another
+the isthmus presents a barrier to the distribution of 75 per cent of
+the species of amphibians living in the lowlands; it is a greater
+barrier still to the species inhabiting the highlands on either side.</p>
+
+<p>Present patterns of distribution are attributed to bioclimatic
+fluctuation in the Pleistocene. In the course of these climatic shifts,
+tropical environments and their amphibian inhabitants seem to have
+survived in the isthmian region.</p>
+
+<p>The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 16 genera and 36 species. Systematic studies of all
+available specimens from the region show that <i>Eleutherodactylus
+conspicuus</i> Taylor and Smith is a synonym of <i>Eleutherodactylus
+alfredi</i> Boulenger and that <i>Hyla axillamembrana</i> Shannon and Werler is
+a synonym of <i>Hyla loquax</i> Gaige and Stuart.</p><hr class="chap" /><p><span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span></p>
+
+
+
+
+<h2><a name="LITERATURE_CITED" id="LITERATURE_CITED"></a>LITERATURE CITED</h2>
+
+
+<p><span class="smcap">Beard, J. S.</span></p>
+
+<p class="i2">1953. The savanna vegetation of northern tropical America.
+Ecol. Mono., vol. 23 (2):149-215.</p>
+
+<p><span class="smcap">Boulenger, G. A.</span></p>
+
+<p class="i2">1898. Fourth report on additions to the batrachian
+collection in the Natural History Museum. Proc. Zool. Soc.
+London, 1898, pp. 473-482, pls. 38-39.</p>
+
+<p><span class="smcap">Burt, C. E.</span></p>
+
+<p class="i2">1931. A study of the teiid lizards of the genus
+<i>Cnemidophorus</i> with special reference to their phylogenetic
+relationships. Bull. U. S. Nat. Mus., No. 154, pp. viii +
+286.</p>
+
+<p><span class="smcap">Contreras A., A.</span></p>
+
+<p class="i2">1942. Mapa de las provincias climatologias de la Republica
+Mexicana. México, D. F., Dirección de Geografía, Meterología
+e Hidrología, pp. i-xxviii, tables 1-54, 2 maps.</p>
+
+<p><span class="smcap">Cooke, C. W.</span></p>
+
+<p class="i2">1945. Geology of Florida. Florida Geol. Surv., Geol. Bull.,
+No. 29:1-339.</p>
+
+<p><span class="smcap">Dorf, E.</span></p>
+
+<p class="i2">1959. Climatic changes of the past and present. Contrib.
+Mus. Paleo. Univ. Michigan, vol. 13 (8):181-210.</p>
+
+<p><span class="smcap">Duellman, W. E.</span></p>
+
+<p class="i2">1956. The frogs of the hylid genus <i>Phrynohyas</i> Fitzinger,
+1843. Miscl. Publ. Mus. Zool. Univ. Michigan, No. 96:1-47,
+pls. 1-6.</p>
+
+<p class="i2">1958a. A monographic study of the colubrid snake genus
+<i>Leptodeira</i>. Bull. Amer. Mus. Nat. Hist., vol. 114:1-152,
+pls. 1-31.</p>
+
+<p class="i2">1958b. A preliminary analysis of the herpetofauna of Colima,
+Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+589:1-22.</p>
+
+<p class="i2">1958c. A review of the frogs of the genus <i>Syrrhophus</i> in
+western Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+594:1-15, pls. 1-3.</p>
+
+<p><span class="smcap">Duellman, W. E.</span>, and <span class="smcap">Schwartz, A.</span></p>
+
+<p class="i2">1958. Amphibians and reptiles of southern Florida. Bull.
+Florida State Mus., vol. 3 (5):181-324.</p>
+
+<p><span class="smcap">Dunn, E. R.</span></p>
+
+<p class="i2">1942. The American caecilians. Bull. Mus. Comp. Zool., vol.
+91 (6):439-540.</p>
+
+<p><span class="smcap">Durham, J. W.</span>, <span class="smcap">Arellano, A. R. V.</span>, and <span class="smcap">Peck, Jr., J. H.</span></p>
+
+<p class="i2">1952. No Cenozoic Tehuantepec seaways. Bull. Geol. Soc.
+Amer., vol. 63:1245.</p>
+
+<p><span class="smcap">Firschein, I. L.</span></p>
+
+<p class="i2">1950. A new toad from Mexico with a redefinition of the
+<i>cristatus</i> group. Copeia, 1950 (2):81-87, pl. 1.</p>
+
+<p class="i2">1954. Definition of some little-understood members of the
+leptodactylid genus <i>Syrrhophus</i>, with a description of a
+new species. Copeia, 1954 (1):48-58.</p>
+
+<p><span class="smcap">Firschein, I. L.</span>, and <span class="smcap">Smith, H. M.</span></p>
+
+<p class="i2">1957. A high-crested race of toad (<i>Bufo valliceps</i>) and
+other noteworthy reptiles and amphibians from southern
+Mexico. Herpetologica, vol. 13 (3):219-222.</p>
+
+<p><span class="smcap">Fugler, C. M.</span>, and <span class="smcap">Webb, R. G.</span></p>
+
+<p class="i2">1957. Some noteworthy reptiles and amphibians from the
+states of Oaxaca and Veracruz. Herpetologica, vol. 13
+(2):103-108.</p>
+
+<p><span class="smcap">Gloyd, H. K.</span></p>
+
+<p class="i2">1940. The rattlesnakes, genera <i>Sistrurus</i> and <i>Crotalus</i>.
+Chicago Acad. Sci. Special Publ., No. 4, vii + 266 pp., pls.
+1-31.</p><p><span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span></p>
+
+<p><span class="smcap">Goin, C. J.</span></p>
+
+<p class="i2">1958. Comments upon the origin of the herpetofauna of
+Florida. Quart. Jour. Florida Acad. Sci., vol. 21 (1):61-70.</p>
+
+<p><span class="smcap">Goldman, E. A.</span></p>
+
+<p class="i2">1951. Biological investigations in Mexico. Smithsonian Misc.
+Publ., vol. 115, xiii + 476 pp., pls. 1-71.</p>
+
+<p><span class="smcap">Goodnight, C. J.</span>, and <span class="smcap">Goodnight, M. L.</span></p>
+
+<p class="i2">1956. Some observations in a tropical rain forest in
+Chiapas, Mexico. Ecology, vol. 37 (1):139-150.</p>
+
+<p><span class="smcap">Griscom, L.</span></p>
+
+<p class="i2">1932. The distribution of bird-life in Guatemala. Bull.
+Amer. Mus. Nat. Hist., vol. 64:1-439.</p>
+
+<p class="i2">1950. Distribution and origin of the birds of Mexico. Bull.
+Mus. Comp. Zool., vol. 103:341-382.</p>
+
+<p><span class="smcap">Hartweg, N.</span>, and <span class="smcap">Oliver, J. A.</span></p>
+
+<p class="i2">1940. A contribution to the herpetology of the Isthmus of
+Tehuantepec. IV. An annotated list of the amphibians and
+reptiles collected on the Pacific slope during the summer of
+1936. Misc. Publ. Mus. Zool. Univ. Michigan, No. 47:1-31.</p>
+
+<p><span class="smcap">Hubbell, T. H.</span></p>
+
+<p class="i2">1954. Relationships and distribution of <i>Mycotrupes</i>. In The
+burrowing beetles of the genus <i>Mycotrupes</i>, Olson, A. L.,
+Hubbell, T. H., and Howden, H. F. Misc. Publ. Mus. Zool.
+Univ. Michigan, No. 84:1-59, pls. 1-8.</p>
+
+<p><span class="smcap">Hutchinson, G. E.</span>, <span class="smcap">Patrick, R.</span>, and <span class="smcap">Deevey, E. S.</span></p>
+
+<p class="i2">1956. Sediments of Lake Patzcuaro, Michoacán, Mexico. Bull.
+Geol. Soc. Amer., vol. 67:1491-1504.</p>
+
+<p><span class="smcap">Langebartel, D. A.</span>, and <span class="smcap">Smith, P. W.</span></p>
+
+<p class="i2">1959. Noteworthy records of amphibians and reptiles from
+eastern Mexico. Herpetologica, vol. 15 (1):27-29.</p>
+
+<p><span class="smcap">Martin, P. S.</span></p>
+
+<p class="i2">1958. Pleistocene ecology and biogeography of North America.
+Zoogeography. Amer. Assoc. Advanc. Sci., Publ. No.
+51:375-420.</p>
+
+<p><span class="smcap">Martin, P. S.</span>, and <span class="smcap">Harrell, B. E.</span></p>
+
+<p class="i2">1957. The Pleistocene history of temperate biotas in Mexico
+and eastern United States. Ecology, vol. 38:468-480.</p>
+
+<p><span class="smcap">Oliver, J. A.</span></p>
+
+<p class="i2">1948. The relationships and zoogeography of the genus
+<i>Thalerophis</i> Oliver. Bull. Amer. Mus. Nat. Hist., vol.
+92:157-280, pls. 16-19.</p>
+
+<p><span class="smcap">Olson, E. C.</span>, and <span class="smcap">McGrew, P. O.</span></p>
+
+<p class="i2">1941. Mammalian fauna from the Pliocene of Honduras. Bull.
+Geol. Soc. Amer., vol. 52:1219-1244.</p>
+
+<p><span class="smcap">Ruthven, A. G.</span></p>
+
+<p class="i2">1912. The amphibians and reptiles collected by the
+University of Michigan&mdash;Walker Expedition in southern Vera
+Cruz, Mexico. Zool. Jahrbuch, vol. 32 (4):295-332, pls.
+6-11.</p>
+
+<p><span class="smcap">Schuchert, C.</span></p>
+
+<p class="i2">1935. Historical geology of the Antillean-Caribbean region.
+New York, xxvi + 811 pp.</p>
+
+<p><span class="smcap">Sears, P. B.</span>, <span class="smcap">Foreman, F.</span>, and <span class="smcap">Clisby, K. H.</span></p>
+
+<p class="i2">1955. Palynology in southern North America. Bull. Geol. Soc.
+Amer., vol. 66:471-530.</p>
+
+<p><span class="smcap">Shannon, F. A.</span>, and <span class="smcap">Werler, J.</span></p>
+
+<p class="i2">1955. Notes on amphibians of the Los Tuxtlas Range of
+Veracruz, Mexico. Trans. Kansas Acad. Sci., vol. 58
+(3):360-386.</p>
+
+<p><span class="smcap">Shreve, B.</span></p>
+
+<p class="i2">1957. Reptiles and amphibians from the Selva Lacandona. <i>In</i>
+Biological Investigations in the Selva Lacandona, Chiapas,
+Mexico. Paynter, R. A. (editor). Bull. Mus. Comp. Zool.,
+vol. 116 (4):193-298.</p><p><span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span></p>
+
+<p><span class="smcap">Smith, H. M.</span></p>
+
+<p class="i2">1947. Notes on Mexican amphibians and reptiles. Jour.
+Washington Acad. Sci., vol. 37:408-412.</p>
+
+<p><span class="smcap">Smith, H. M.</span>, and <span class="smcap">Laufe, L. E.</span></p>
+
+<p class="i2">1946. A summary of Mexican Lizards of the genus <i>Ameiva</i>.
+Univ. Kansas Sci. Bull., vol. 31 (2):7-73.</p>
+
+<p><span class="smcap">Smith, H. M.</span>, and <span class="smcap">Taylor, E. H.</span></p>
+
+<p class="i2">1950. An annotated checklist and key to the reptiles of
+Mexico exclusive of the snakes. Bull. U. S. Natl. Mus., No.
+199, v + 253 pp.</p>
+
+<p><span class="smcap">Stirton, R. A.</span></p>
+
+<p class="i2">1954. Late Miocene mammals from Oaxaca, Mexico. Amer. Jour.
+Sci., No. 252:634-638.</p>
+
+<p><span class="smcap">Stuart, L. C.</span></p>
+
+<p class="i2">1935. A contribution to a knowledge of the herpetology of a
+portion of the savanna region of central Petén, Guatemala.
+Misc. Publ. Mus. Zool. Univ. Michigan, No. 29:1-56, pls.
+1-4.</p>
+
+<p class="i2">1941. Studies of Neotropical Colubridae VIII. A revision of
+the genus <i>Dryadophis</i> Stuart, 1939. Misc. Publ. Mus. Zool.
+Univ. Michigan, No. 49:1-106, pls. 1-4.</p>
+
+<p class="i2">1951. The herpetofauna of the Guatemalan Plateau, with
+special reference to its distribution on the southwestern
+highlands. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+No. 49:1-71, pls. 1-7.</p>
+
+<p class="i2">1954. A description of a subhumid corridor across northern
+Central America, with comments on its herpetofaunal
+indicators. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+No. 65:1-26, pls. 1-6.</p>
+
+<p class="i2">1958. A study of the herpetofauna of the Uaxactun-Tikal area
+of northern El Petén, Guatemala. Contrib. Lab. Vertebrate
+Biol., Univ. Michigan, No. 75:1-30.</p>
+
+<p><span class="smcap">Taylor, E. H.</span></p>
+
+<p class="i2">1940. New species of Mexican Anura. Univ. Kansas Sci. Bull.,
+vol. 26 (11):385-405.</p>
+
+<p class="i2">1941. New amphibians from the Hobart M. Smith Mexican
+collections. Univ. Kansas Sci. Bull., vol. 27 (8):141-167.</p>
+
+<p class="i2">1942. The frog genus <i>Diaglena</i> with a description of a new
+species. Univ. Kansas Sci. Bull., vol. 28 (4):57-65.</p>
+
+<p class="i2">1943a. A new <i>Hylella</i> from Mexico. Proc. Biol. Soc.
+Washington, vol. 56:49-52.</p>
+
+<p class="i2">1943b. Herpetological novelties from Mexico. Univ. Kansas
+Sci. Bull., vol. 29 (8):343-361.</p>
+
+<p><span class="smcap">Taylor, E. H.</span>, and <span class="smcap">Smith, H. M.</span></p>
+
+<p class="i2">1945. Summary of the collections of amphibians made in
+Mexico under the Walter Rathbone Bacon Traveling
+Scholarship. Proc. U. S. Natl. Mus., vol. 95:521-613, pls.
+18-32.</p>
+
+<p><span class="smcap">Trask, P. D.</span>, <span class="smcap">Phleger, F. B.</span>, and <span class="smcap">Stetson, H. C.</span></p>
+
+<p class="i2">1947. Recent changes in sedimentation in the Gulf of Mexico.
+Science, vol. 106:460-461.</p>
+
+<p><span class="smcap">Weyl, R.</span></p>
+
+<p class="i2">1955. Vestigios de una glaciacion del Pleistoceno en la
+Cordillera de Talamanca, Costa Rica, A. C. Informe
+Trimestral, Inst. Geog. de Costa Rica, pp. 9-32.</p>
+
+<p><span class="smcap">White, S. E.</span></p>
+
+<p class="i2">1956. Probable substages of glaciation on Ixtaccihuatl,
+Mexico. Jour. Geol., vol. 64:289-295.</p>
+
+<p><span class="smcap">Williams, L.</span></p>
+
+<p class="i2">1939. Arboles y arbustos del Istmos de Tehuantepec, Mexico.
+Lilloa., vol. 4:137-171.</p>
+
+<p>
+<span style="margin-left: 1em;"><i>Transmitted May 23, 1960.</i></span>
+</p>
+<hr class="full" />
+
+
+<p><span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span></p>
+<h2><a name="UNIVERSITY_OF_KANSAS_PUBLICATIONS_MUSEUM_OF_NATURAL_HISTORY" id="UNIVERSITY_OF_KANSAS_PUBLICATIONS_MUSEUM_OF_NATURAL_HISTORY"></a>UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY</h2>
+
+
+<p>Institutional libraries interested in publications exchange may obtain
+this series by addressing the Exchange Librarian, University of Kansas
+Library, Lawrence, Kansas. Copies for individuals, persons working in a
+particular field of study, may be obtained by addressing instead the
+Museum of Natural History, University of Kansas, Lawrence, Kansas.
+There is no provision for sale of this series by the University
+Library, which meets institutional requests, or by the Museum of
+Natural History, which meets the requests of individuals. However, when
+individuals request copies from the Museum, 25 cents should be
+included, for each separate number that is 100 pages or more in length,
+for the purpose of defraying the costs of wrapping and mailing.</p>
+
+<p>* An asterisk designates those numbers of which the Museum's supply
+(not the Library's supply) is exhausted. Numbers published to date, in
+this series, are as follows:</p>
+
+<p>
+<span style="margin-left: 0.5em;">Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950.</span><br />
+<br />
+*Vol. 2.  (Complete) Mammals of Washington. By Walter W. Dalquest.<br />
+<span style="margin-left: 6.5em;">Pp. 1-444, 140 figures in text. April 9, 1948.</span><br />
+<br />
+<span style="margin-left: 0.5em;">Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and</span><br />
+<span style="margin-left: 6.5em;">distribution. By Rollin H. Baker. Pp. 1-359, 16 figures</span><br />
+<span style="margin-left: 6.5em;">in text. June 12, 1951.</span><br />
+<br />
+<span style="margin-left: 4.5em;">*2. A quantitative study of the nocturnal migration of birds.</span><br />
+<span style="margin-left: 6.5em;">By George H. Lowery, Jr. Pp. 361-472, 47 figures in text.</span><br />
+<span style="margin-left: 6.5em;">June 29, 1951.</span><br />
+<br />
+<span style="margin-left: 5em;">3. Phylogeny of the waxwings and allied birds. By M. Dale</span><br />
+<span style="margin-left: 6.5em;">Arvey. Pp. 473-530, 49 figures in text, 13 tables.</span><br />
+<span style="margin-left: 6.5em;">October 10, 1951.</span><br />
+<br />
+<span style="margin-left: 5em;">4. Birds from the state of Veracruz, Mexico. By George H.</span><br />
+<span style="margin-left: 6.5em;">Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7</span><br />
+<span style="margin-left: 6.5em;">figures in text, 2 tables. October 10, 1951.</span><br />
+<br />
+<span style="margin-left: 5em;">Index. Pp. 651-681.</span><br />
+<br />
+*Vol. 4.  (Complete) American weasels. By E. Raymond Hall. Pp. 1-466,<br />
+<span style="margin-left: 6.5em;">41 plates, 31 figures in text. December 27, 1951.</span><br />
+<br />
+<span style="margin-left: 0.5em;">Vol. 5.&nbsp; Nos. 1-37 and index. Pp. 1-676, 1951-1953.</span><br />
+<br />
+*Vol. 6.  (Complete) Mammals of Utah, <i>taxonomy and distribution</i>. By<br />
+<span style="margin-left: 6.5em;">Stephen D. Durrant. Pp. 1-549, 91 figures in text, 80</span><br />
+<span style="margin-left: 6.5em;">tables. August 10, 1952.</span><br />
+<br />
+<span style="margin-left: 0.5em;">Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73</span><br />
+<span style="margin-left: 6.5em;">figures in text, 37 tables. August 25, 1952.</span><br />
+<br />
+<span style="margin-left: 5em;">2. Ecology of the opossum on a natural area in northeastern</span><br />
+<span style="margin-left: 6.5em;">Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp.</span><br />
+<span style="margin-left: 6.5em;">305-338, 5 figures in text. August 24, 1953.</span><br />
+<br />
+<span style="margin-left: 5em;">3. The silky pocket mice (Perognathus flavus) of Mexico. By</span><br />
+<span style="margin-left: 6.5em;">Rollin H. Baker. Pp. 339-347, 1 figure in text. February</span><br />
+<span style="margin-left: 6.5em;">15, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">4. North American jumping mice (Genus Zapus). By Philip H.</span><br />
+<span style="margin-left: 6.5em;">Krutzsch. Pp. 349-472, 47 figures in text, 4 tables.</span><br />
+<span style="margin-left: 6.5em;">April 21, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">5. Mammals from Southeastern Alaska. By Rollin H. Baker and</span><br />
+<span style="margin-left: 6.5em;">James S. Findley. Pp. 473-477. April 21, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">6. Distribution of Some Nebraskan Mammals. By J. Knox Jones,</span><br />
+<span style="margin-left: 6.5em;">Jr. Pp. 479-487. April 21, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">7. Subspeciation in the montane meadow mouse. Microtus</span><br />
+<span style="margin-left: 6.5em;">montanus, in Wyoming and Colorado. By Sydney Anderson.</span><br />
+<span style="margin-left: 6.5em;">Pp. 489-506, 2 figures in text. July 23, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">8. A new subspecies of bat (Myotis velifer) from southeastern</span><br />
+<span style="margin-left: 6.5em;">California and Arizona. By Terry A. Vaughan. Pp. 507-512.</span><br />
+<span style="margin-left: 6.5em;">July 23, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">9. Mammals of the San Gabriel mountains of California. By</span><br />
+<span style="margin-left: 6.5em;">Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12</span><br />
+<span style="margin-left: 6.5em;">tables. November 15, 1954.</span><br />
+<br />
+<span style="margin-left: 4.5em;">10. A new bat (Genus Pipistrellus) from northeastern Mexico.</span><br />
+<span style="margin-left: 6.5em;">By Rollin H. Baker. Pp. 583-586. November 15, 1954.</span><br />
+<br />
+<span style="margin-left: 4.5em;">11. A new subspecies of pocket mouse from Kansas. By E.</span><br />
+<span style="margin-left: 6.5em;">Raymond Hall. Pp. 587-590. November 15, 1954.</span><br />
+<br />
+<span style="margin-left: 4.5em;">12. Geographic variation in the pocket gopher, Cratogeomys</span><br />
+<span style="margin-left: 6.5em;">castanops, in Coahuila, Mexico. By Robert J. Russell and</span><br />
+<span style="margin-left: 6.5em;">Rollin H. Baker. Pp. 591-608. March 15, 1955.</span><br />
+<br />
+<span style="margin-left: 4.5em;">13. A new cottontail (Sylvilagus floridanus) from northeastern</span><br />
+<span style="margin-left: 6.5em;">Mexico. By Rollin H. Baker. Pp. 609-612. April 8, 1955.</span><br />
+<br />
+<span style="margin-left: 4.5em;">14. Taxonomy and distribution of some American shrews. By</span><br />
+<span style="margin-left: 6.5em;">James S. Findley. Pp. 613-618. June 10, 1955.</span><br />
+<br />
+<span style="margin-left: 4.5em;">15. The pigmy woodrat, Neotoma goldmani, its distribution and</span><br />
+<span style="margin-left: 6.5em;">systematic position. By Dennis G. Rainey and Rollin H.</span><br />
+<span style="margin-left: 6.5em;">Baker. Pp. 619-624. 2 figures in text. June 10, 1955.</span><br />
+<br />
+<span style="margin-left: 5em;">Index. Pp. 625-651.</span><br />
+<br />
+<span style="margin-left: 0.5em;">Vol. 8.&nbsp; 1. Life history and ecology of the five-lined skink, Eumeces</span><br />
+<span style="margin-left: 6.5em;">fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in</span><br />
+<span style="margin-left: 6.5em;">text. September 1, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">2. Myology and serology of the Avian Family Fringillidae, a</span><br />
+<span style="margin-left: 6.5em;">taxonomic study. By William B. Stallcup. Pp. 157-211, 23</span><br />
+<span style="margin-left: 6.5em;">figures in text, 4 tables. November 15, 1954.</span><br />
+<br />
+<span style="margin-left: 5em;">3. An ecological study of the collared lizard (Crotaphytus</span><br />
+<span style="margin-left: 6.5em;">collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in</span><br />
+<span style="margin-left: 6.5em;">text. February 10, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">4. A field study of the Kansas ant-eating frog, Gastrophryne</span><br />
+<span style="margin-left: 6.5em;">olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in</span><br />
+<span style="margin-left: 6.5em;">text. February 10, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">5. Check-list of the birds of Kansas. By Harrison B. Tordoff.</span><br />
+<span style="margin-left: 6.5em;">Pp. 307-359, 1 figure in text. March 10, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">6. A population study of the prairie vole (Microtus</span><br />
+<span style="margin-left: 6.5em;">ochrogaster) in northeastern Kansas. By Edwin P. Martin.</span><br />
+<span style="margin-left: 6.5em;">Pp. 361-416, 19 figures in text. April 2, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">7. Temperature responses in free-living amphibians and</span><br />
+<span style="margin-left: 6.5em;">reptiles of northeastern Kansas. By Henry S. Fitch. Pp.</span><br />
+<span style="margin-left: 6.5em;">417-476, 10 figures in text, 6 tables. June 1, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">8. Food of the crow, Corvus brachyrhynchos Brehm, in</span><br />
+<span style="margin-left: 6.5em;">south-central Kansas. By Dwight Platt. Pp. 477-498, 4</span><br />
+<span style="margin-left: 6.5em;">tables. June 8, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">9. Ecological observations on the woodrat, Neotoma floridana.</span><br />
+<span style="margin-left: 6.5em;">By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3</span><br />
+<span style="margin-left: 6.5em;">figures in text. June 12, 1956.</span><br />
+<br />
+<span style="margin-left: 4.5em;">10. Eastern woodrat, Neotoma floridana: Life history and</span><br />
+<span style="margin-left: 6.5em;">ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13</span><br />
+<span style="margin-left: 6.5em;">figures in text. August 15, 1956.</span><br />
+<br />
+<span style="margin-left: 4.5em;">Index. Pp. 647-675.</span><br />
+<br />
+<span style="margin-left: 0.5em;">Vol. 9.&nbsp; 1. Speciation of the wandering shrew. By James S. Findley.</span><br />
+<span style="margin-left: 6.5em;">Pp. 1-68, 18 figures in text. December 10, 1955.</span><br />
+<br />
+<span style="margin-left: 5em;">2. Additional records and extensions of ranges of mammals</span><br />
+<span style="margin-left: 6.5em;">from Utah. By Stephen D. Durrant, M. Raymond Lee, and</span><br />
+<span style="margin-left: 6.5em;">Richard M. Hansen. Pp. 69-80. December 10, 1955.</span><br />
+<br />
+<span style="margin-left: 5em;">3. A new long-eared myotis (Myotis evotis) from northeastern</span><br />
+<span style="margin-left: 6.5em;">Mexico. By Rollin H. Baker and Howard J. Stains. Pp.</span><br />
+<span style="margin-left: 6.5em;">81-84. December 10, 1955.</span><br />
+<br />
+<span style="margin-left: 5em;">4. Subspeciation in the meadow mouse, Microtus pennsylvanicus,</span><br />
+<span style="margin-left: 6.5em;">in Wyoming. By Sydney Anderson. Pp. 85-104, 2 figures in</span><br />
+<span style="margin-left: 6.5em;">text. May 10, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">5. The condylarth genus Ellipsodon. By Robert W. Wilson.</span><br />
+<span style="margin-left: 6.5em;">Pp. 105-116, 6 figures in text. May 19, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">6. Additional remains of the multituberculate genus</span><br />
+<span style="margin-left: 6.5em;">Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures</span><br />
+<span style="margin-left: 6.5em;">in text. May 19, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp.</span><br />
+<span style="margin-left: 6.5em;">125-335, 75 figures in text. June 15, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">8. Comments on the taxonomic status of Apodemus peninsulae,</span><br />
+<span style="margin-left: 6.5em;">with description of a new subspecies from North China. By</span><br />
+<span style="margin-left: 6.5em;">J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1</span><br />
+<span style="margin-left: 6.5em;">table. August 15, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">9. Extensions of known ranges of Mexican bats. By Sydney</span><br />
+<span style="margin-left: 6.5em;">Anderson. Pp. 347-351. August 15, 1956.</span><br />
+<br />
+<span style="margin-left: 4.5em;">10. A new bat (Genus Leptonycteris) from Coahuila. By Howard</span><br />
+<span style="margin-left: 6.5em;">J. Stains. Pp. 353-356. January 21, 1957.</span><br />
+<br />
+<span style="margin-left: 4.5em;">11. A new species of pocket gopher (Genus Pappogeomys) from</span><br />
+<span style="margin-left: 6.5em;">Jalisco, Mexico. By Robert J. Russell. Pp. 357-361.</span><br />
+<span style="margin-left: 6.5em;">January 21, 1957.</span><br />
+<br />
+<span style="margin-left: 4.5em;">12. Geographic variation in the pocket gopher, Thomomys</span><br />
+<span style="margin-left: 6.5em;">bottae, in Colorado. By Phillip M. Youngman. Pp. 363-384,</span><br />
+<span style="margin-left: 6.5em;">7 figures in text. February 21, 1958.</span><br />
+<br />
+<span style="margin-left: 4.5em;">13. New bog lemming (genus Synaptomys) from Nebraska. By J.</span><br />
+<span style="margin-left: 6.5em;">Knox Jones, Jr. Pp. 385-388. May 12, 1958.</span><br />
+<br />
+<span style="margin-left: 4.5em;">14. Pleistocene bats from San Josecito Cave, Nuevo León,</span><br />
+<span style="margin-left: 6.5em;">México. By J. Knox Jones, Jr. Pp. 389-396. December 19,</span><br />
+<span style="margin-left: 6.5em;">1958.</span><br />
+<br />
+<span style="margin-left: 4.5em;">15. New Subspecies of the rodent Baiomys from Central America.</span><br />
+<span style="margin-left: 6.5em;">By Robert L. Packard. Pp. 397-404. December 19, 1958.</span><br />
+<br />
+<span style="margin-left: 4.5em;">16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson.</span><br />
+<span style="margin-left: 6.5em;">Pp. 405-414, 1 figure in text. May 20, 1959.</span><br />
+<br />
+<span style="margin-left: 4.5em;">17. Distribution, variation, and relationships of the montane</span><br />
+<span style="margin-left: 6.5em;">vole, Microtus montanus. By Emil K. Urban. Pp. 415-511.</span><br />
+<span style="margin-left: 6.5em;">12 figures in text, 2 tables. August 1, 1959.</span><br />
+<br />
+<span style="margin-left: 4.5em;">18. Conspecificity of two pocket mice, Perognathus goldmani</span><br />
+<span style="margin-left: 6.5em;">and P. artus. By E. Raymond Hall and Marilyn Bailey</span><br />
+<span style="margin-left: 6.5em;">Ogilvie. Pp. 513-518, 1 map. January 14, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">19. Records of harvest mice, Reithrodontomys, from Central</span><br />
+<span style="margin-left: 6.5em;">America, with description of a new subspecies from</span><br />
+<span style="margin-left: 6.5em;">Nicaragua. By Sydney Anderson and J. Knox Jones, Jr. Pp.</span><br />
+<span style="margin-left: 6.5em;">519-529. January 14, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">20. Small carnivores from San Josecito Cave (Pleistocene),</span><br />
+<span style="margin-left: 6.5em;">Nuevo León, México. By E. Raymond Hall. Pp. 531-538, 1</span><br />
+<span style="margin-left: 6.5em;">figure in text. January 14, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">21. Pleistocene pocket gophers from San Josecito Cave, Nuevo</span><br />
+<span style="margin-left: 6.5em;">León, México. By Robert J. Russell. Pp. 539-548, 1 figure</span><br />
+<span style="margin-left: 6.5em;">in text. January 14, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">22. Review of the insectivores of Korea. By J. Knox Jones,</span><br />
+<span style="margin-left: 6.5em;">Jr., and David H. Johnson. Pp. 549-578. February 23, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">23. Speciation and evolution of the pygmy mice, genus Baiomys.</span><br />
+<span style="margin-left: 6.5em;">By Robert L. Packard. Pp. 579-670, 4 plates, 12 figures in</span><br />
+<span style="margin-left: 6.5em;">text. June 16, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">Index Pp. 671-690.</span><br />
+<br />
+Vol. 10.  1. Studies of birds killed in nocturnal migration. By<br />
+<span style="margin-left: 6.5em;">Harrison B. Tordoff and Robert M. Mengel. Pp. 1-44, 6</span><br />
+<span style="margin-left: 6.5em;">figures in text, 2 tables. September 12, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">2. Comparative breeding behavior of Ammospiza caudacuta and</span><br />
+<span style="margin-left: 6.5em;">A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates,</span><br />
+<span style="margin-left: 6.5em;">1 figure. December 20, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">3. The forest habitat of the University of Kansas Natural</span><br />
+<span style="margin-left: 6.5em;">History Reservation. By Henry S. Fitch and Ronald R.</span><br />
+<span style="margin-left: 6.5em;">McGregor. Pp. 77-127, 2 plates, 7 figures in text, 4</span><br />
+<span style="margin-left: 6.5em;">tables. December 31, 1956.</span><br />
+<br />
+<span style="margin-left: 5em;">4. Aspects of reproduction and development in the prairie</span><br />
+<span style="margin-left: 6.5em;">vole (Microtus ochrogaster). By Henry S. Fitch. Pp.</span><br />
+<span style="margin-left: 6.5em;">129-161, 8 figures in text, 4 tables. December 19, 1957.</span><br />
+<br />
+<span style="margin-left: 5em;">5. Birds found on the Arctic slope of northern Alaska. By</span><br />
+<span style="margin-left: 6.5em;">James W. Bee. Pp. 163-211, pls. 9-10, 1 figure in text.</span><br />
+<span style="margin-left: 6.5em;">March 12, 1958.</span><br />
+<br />
+<span style="margin-left: 5em;">6. The wood rats of Colorado: distribution and ecology. By</span><br />
+<span style="margin-left: 6.5em;">Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures</span><br />
+<span style="margin-left: 6.5em;">in text, 35 tables. November 7, 1958.</span><br />
+<br />
+<span style="margin-left: 5em;">7. Home ranges and movements of the eastern cottontail in</span><br />
+<span style="margin-left: 6.5em;">Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3</span><br />
+<span style="margin-left: 6.5em;">figures in text. May 4, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">8. Natural history of the salamander, Aneides hardyi. By</span><br />
+<span style="margin-left: 6.5em;">Richard F. Johnston and Schad Gerhard. Pp. 573-585.</span><br />
+<span style="margin-left: 6.5em;">October 8, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">9. A new subspecies of lizard, Cnemidophorus sacki, from</span><br />
+<span style="margin-left: 6.5em;">Michoacán, México. By William E. Duellman. Pp. 587-598,</span><br />
+<span style="margin-left: 6.5em;">2 figures in text. May 2, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">10. A taxonomic study of the Middle American Snake, Pituophis</span><br />
+<span style="margin-left: 6.5em;">deppei. By William E. Duellman. Pp. 599-610, 1 plate, 1</span><br />
+<span style="margin-left: 6.5em;">figure in text. May 2, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">Index Pp. 611-626.</span><br />
+<br />
+Vol. 11.  1. The systematic status of the colubrid snake, Leptodeira<br />
+<span style="margin-left: 6.5em;">discolor Günther. By William E. Duellman. Pp. 1-9, 4</span><br />
+<span style="margin-left: 6.5em;">figs. July 14, 1958.</span><br />
+<br />
+<span style="margin-left: 5em;">2. Natural history of the six-lined racerunner, Cnemidophorus</span><br />
+<span style="margin-left: 6.5em;">sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figs., 9</span><br />
+<span style="margin-left: 6.5em;">tables. September 19, 1958.</span><br />
+<br />
+<span style="margin-left: 5em;">3. Home ranges, territories, and seasonal movements of</span><br />
+<span style="margin-left: 6.5em;">vertebrates of the Natural History Reservation. By Henry</span><br />
+<span style="margin-left: 6.5em;">S. Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3</span><br />
+<span style="margin-left: 6.5em;">tables. December 12, 1958.</span><br />
+<br />
+<span style="margin-left: 5em;">4. A new snake of the genus Geophis from Chihuahua, Mexico.</span><br />
+<span style="margin-left: 6.5em;">By John M. Legler. Pp. 327-334, 2 figures in text.</span><br />
+<span style="margin-left: 6.5em;">January 28, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">5. A new tortoise, genus Gopherus, from north-central</span><br />
+<span style="margin-left: 6.5em;">Mexico. By John M. Legler. Pp. 335-343. April 24, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By</span><br />
+<span style="margin-left: 6.5em;">Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in</span><br />
+<span style="margin-left: 6.5em;">text, 10 tables. May 6, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">7. Fishes of the Big Blue River Basin, Kansas. By W. L.</span><br />
+<span style="margin-left: 6.5em;">Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5</span><br />
+<span style="margin-left: 6.5em;">tables. May 8, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">8. Birds from Coahuila, México. By Emil K. Urban. Pp.</span><br />
+<span style="margin-left: 6.5em;">443-516. August 1, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">9. Description of a new softshell turtle from the</span><br />
+<span style="margin-left: 6.5em;">southeastern United States. By Robert G. Webb. Pp.</span><br />
+<span style="margin-left: 6.5em;">517-525, 2 pls., 1 figure in text, August 14, 1959.</span><br />
+<br />
+<span style="margin-left: 4.5em;">10. Natural history of the ornate box turtle, Terrapene</span><br />
+<span style="margin-left: 6.5em;">ornata ornata Agassiz. By John M. Legler. Pp. 527-669,</span><br />
+<span style="margin-left: 6.5em;">16 pls., 29 figures in text. March 7, 1960.</span><br />
+<br />
+<span style="margin-left: 4.5em;">Index will follow.</span><br />
+<br />
+Vol. 12.  1. Functional morphology of three bats: Eumops, Myotis,<br />
+<span style="margin-left: 6.5em;">Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24</span><br />
+<span style="margin-left: 6.5em;">figures in text, July 8, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">2. The ancestry of modern Amphibia: a review of the</span><br />
+<span style="margin-left: 6.5em;">evidence. By Theodore H. Eaton, Jr. Pp. 155-180, 10</span><br />
+<span style="margin-left: 6.5em;">figures in text. July 10, 1959.</span><br />
+<br />
+<span style="margin-left: 5em;">3. The baculum in microtine rodents. By Sydney Anderson.</span><br />
+<span style="margin-left: 6.5em;">Pp. 181-216, 49 figures in text. February 19, 1960.</span><br />
+<br />
+<span style="margin-left: 5em;">4. A new order of fishlike Amphibia from the Pennsylvanian</span><br />
+<span style="margin-left: 6.5em;">of Kansas. By Theodore H. Eaton, Jr., and Peggy Lou</span><br />
+<span style="margin-left: 6.5em;">Stewart. Pp. 217-240, 12 figures in text. May 2, 1960.</span><br />
+<br />
+<span style="margin-left: 5em;">More numbers will appear in volume 12.</span><br />
+<br />
+Vol. 13.  1. Five natural hybrid combinations in minnows (Cyprinidae).<br />
+<span style="margin-left: 6.5em;">By Frank B. Cross and W. L. Minckley. Pp. 1-18. June 1,</span><br />
+<span style="margin-left: 6.5em;">1960.</span><br />
+<br />
+<span style="margin-left: 5em;">2. A distributional study of the amphibians of the isthmus</span><br />
+<span style="margin-left: 6.5em;">of Tehuantepec, México. By William E. Duellman.</span><br />
+<span style="margin-left: 6.5em;">Pp. 19-72, pls. 1-8, 3 figs. August 16, 1960.</span><br />
+<br />
+<span style="margin-left: 5em;">More numbers will appear in volume 13.</span><br />
+</p>
+
+<hr class="full" />
+
+
+<p class="transnote">Transcriber's Notes<br /><br />
+
+
+
+Page <a href="#Page_26">26</a>: Changed "19. Cosaleacaque" to "19. Cosoleacaque".<br />
+<br />
+Page <a href="#Page_30">30</a>: Changed "Brysonima crassifolia" to "Byrsonima crassifolia".<br />
+<br />
+Page <a href="#Page_34">34</a>: Changed "long. 95' 29°;" to "long. 95° 29';".<br />
+<br />
+Page <a href="#Page_35">35</a>: Changed "Matías Romera" to "Matías Romero".<br />
+<br />
+Page <a href="#Page_47">47</a>: Changed "kown" to "known".<br />
+<br />
+Pages <a href="#Page_50">50</a> and <a href="#Page_59">59</a>: Changed "axills" to "axils".<br />
+<br />
+<a href="#pl1-fig2">Plate 1, Fig. 2</a>: Changed "Veracuz" to "Veracruz".<br />
+<br />
+Page <a href="#Page_53">53</a>: Changed "valadity" to "validity".<br />
+<br />
+Page <a href="#Page_67">67</a>: Changed "refering" to "referring".<br />
+<br />
+Page <a href="#Page_68">68</a>: Changed "survided" to "survived".<br />
+<br />
+Page <a href="#Page_71">71</a>: Changed "subhimid" to "subhumid" and "Amerca" to "America".<br />
+<br />
+Moved University of Kansas <a href="#UNIVERSITY_OF_KANSAS_PUBLICATIONS_MUSEUM_OF_NATURAL_HISTORY">Publications list</a> to end of report.<br />
+Vol. 9, No. 12: Changed pages from "363-387" to "363-384".<br />
+Vol. 10, No. 10: Changed pages from "599-612" to "599-610".<br />
+</p>
+
+
+
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of A Distributional Study of the
+Amphibians of the Isthmus of Tehuantepec, Mexico, by William E. Duellman
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+</body>
+</html>
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@@ -0,0 +1,3641 @@
+The Project Gutenberg EBook of A Distributional Study of the Amphibians of
+the Isthmus of Tehuantepec, Mexico, by William E. Duellman
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: A Distributional Study of the Amphibians of the Isthmus of Tehuantepec, Mexico
+
+Author: William E. Duellman
+
+Release Date: December 30, 2011 [EBook #38440]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK A DISTRIBUTIONAL STUDY OF ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+
+August 16, 1960
+
+A Distributional Study of the Amphibians
+of the Isthmus of Tehuantepec, Mexico
+
+BY
+WILLIAM E. DUELLMAN
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1960
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+
+August 16, 1960
+
+A Distributional Study of the Amphibians
+of the Isthmus of Tehuantepec, Mexico
+
+BY
+WILLIAM E. DUELLMAN
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1960
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
+Robert W. Wilson
+
+Volume 13, No. 2, pp. 19-72, pls. 1-8, 3 figs.
+Published August 16, 1960
+
+UNIVERSITY OF KANSAS
+Lawrence, Kansas
+
+PRINTED IN
+THE STATE PRINTING PLANT
+TOPEKA, KANSAS
+1960
+
+28-3859
+
+
+
+
+A Distributional Study of the Amphibians of the Isthmus of Tehuantepec,
+Mexico
+
+BY
+
+WILLIAM E. DUELLMAN
+
+
+
+
+CONTENTS
+
+
+                                                               PAGE
+INTRODUCTION                                                     21
+  Acknowledgments                                                23
+  Field Studies in the Isthmus of Tehuantepec                    23
+  Sources of Material                                            24
+
+DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC                        25
+  Physiography                                                   25
+  Climate                                                        28
+  Vegetation                                                     29
+  The Sierra de los Tuxtlas                                      32
+
+GAZETTEER                                                        33
+
+THE AMPHIBIAN FAUNA OF THE LOWLANDS                              37
+  Composition of the Fauna                                       37
+  Ecology of the Fauna                                           38
+  Distribution of the Fauna                                      42
+
+THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS      44
+
+ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION                45
+
+ACCOUNTS OF SPECIES                                              49
+
+SUMMARY                                                          68
+
+LITERATURE CITED                                                 69
+
+
+
+
+INTRODUCTION
+
+
+Few regions in Middle America are so important zoogeographically as is
+the Isthmus of Tehuantepec, that neck of land connecting North America
+with Central America, separating the Pacific Ocean from the Gulf of
+Mexico by a distance of only about 220 kilometers (airline), and
+forming a low break between the highlands of Mexico and those of
+Central America. Before World War II the isthmus could be reached
+readily only by railroad or by ocean vessel to Salina Cruz or
+Coatzacoalcos. With the advent of roads, principally the Trans-isthmian
+Highway, vast areas of the interior of the isthmus became accessible to
+biologists. Nevertheless, long before roads were built in the isthmian
+region collectors and biologists visited it, especially the town of
+Tehuantepec, from which collections date back to the 1870's. Therefore,
+it is rather surprising that no attempt has been made to present a
+faunal list of the amphibians or reptiles of the isthmus. Ruthven
+(1912) summarized his collections from the vicinity of Cuatotolapam,
+Veracruz, and Hartweg and Oliver (1940) presented an annotated list of
+the species collected by them in the vicinity of Tehuantepec. In recent
+years there have been only a few papers reporting species from the
+isthmus (Fugler and Webb, 1957; Langebartel and Smith, 1959). The
+zoogeographic significance of the Isthmus of Tehuantepec is exemplified
+by the works of Burt (1931), Duellman (1958), Gloyd (1940), Oliver
+(1948), and Stuart (1941), who in their discussions of evolution and
+dispersal of various genera of reptiles, pointed out that the Isthmus
+of Tehuantepec was a region of zoogeographic importance.
+
+Originally I intended to study the entire herpetofauna of the isthmus.
+But I have not had opportunity to study all of the reptiles, and I have
+not had the inclination to solve certain taxonomic problems concerning
+them. The amphibians that I collected, together with all other known
+specimens in museums, have been studied. Therefore, the present report
+is concerned only with the amphibians. Only the amphibians of the
+lowlands of the isthmus have been sampled adequately. Although I have
+commented on the highland species in the discussion of distribution,
+they are not included in the systematic section, which deals solely
+with the 36 species definitely known to occur in the lowlands of the
+isthmus.
+
+Among the species of amphibians that I would expect to occur in the
+isthmus, the only one not yet found there is _Hyla phaeota_. Sufficient
+specimens of most of the species are available to show their variation
+in the isthmus. Consequently, the systematics of these amphibians is on
+a fairly substantial basis. Probably certain species in the isthmian
+region will be found to be conspecific with others to the south, for
+example _Hyla ebraccata_ with _Hyla leucophyllata_ and _Hyla
+robertmertensi_ with _Hyla underwoodi_. Nevertheless, such taxonomic
+changes will not affect the distributional picture presented here. Our
+greatest lack of knowledge concerning the amphibians is about their
+life histories, as may be illustrated by the following questions, all
+of which now are without definite answers. Where do many of the small
+frogs conceal themselves during the dry season? What amount of, if any,
+interspecific competition exists among several species of tree frogs,
+all of which breed in the same ponds? What factors in the environment
+permit certain amphibians, but not others, to live in the humid
+rainforests, as well as in the arid tropical scrub forest? The answers
+to these questions and many others must await additional field studies.
+
+The purpose of this paper is to make known the species of amphibians
+living in the Isthmus of Tehuantepec, to describe the environments in
+which they live, and to discuss their distribution in the isthmus. With
+respect to the distribution of animals in the Isthmus of Tehuantepec I
+will attempt to explain the present patterns of distribution with
+special reference to climatic fluctuation in the Pleistocene.
+
+
+_Acknowledgments_
+
+My extensive field work in the Isthmus of Tehuantepec was made possible
+by grants from the Penrose Fund of the American Philosophical Society
+(1956) and the Bache Fund of the National Academy of Sciences (1958).
+Furthermore, my field work received the hearty support of the Museum of
+Zoology at the University of Michigan; for their cooperation I am
+indebted to Norman Hartweg, T. H. Hubbell, and Henry van der Schalie.
+In the course of my studies I received helpful suggestions from Norman
+Hartweg, L. C. Stuart, and Charles F. Walker, to whom I am grateful.
+For permission to examine specimens in their care I thank Doris M.
+Cochran, Hobart M. Smith, and Richard G. Zweifel. I am deeply indebted
+to Thomas MacDougall for many suggestions and for aid in preparing the
+gazetteer. I am most grateful for the efforts of my field companions,
+Richard E. Etheridge, Jerome B. Tulecke, John Wellman, and especially
+my wife, Ann S. Duellman, who spent many long days and nights gathering
+much of the data on which this report is based. Our work in the isthmus
+was furthered by the generous help and hospitality of many residents,
+especially the late Wilbur Barker of Tehuantepec, Fortunado Delgado of
+Rancho Las Hojitas near Acayucan, Cesar Farjas of Donaji, and Juan
+Mayol of San Andres Tuxtla. Profesor Jordi Julia Z. of the Laboratorio
+de Entomologia, Comision del Papaloapan, Ciudad Aleman, Veracruz,
+helped make possible my field work in 1959; for this he has my sincere
+thanks. In conclusion I express my gratitude to Ing. Juan Lozano
+Franco, Secretaria de Agricultura y Ganaderia, for providing me with
+the necessary permits.
+
+
+_Field Studies in the Isthmus of Tehuantepec_
+
+I first visited the Isthmus of Tehuantepec and collected on the Pacific
+lowlands of the isthmus in July, 1955. At that time heavy rains and
+impassable roads restricted travelling. In February and March of 1956
+my wife and I concentrated our efforts in the central region between
+the Rio Jaltepec and Matias Romero, but also made several trips across
+the isthmus to gather ecological data in the dry season. In July of the
+same year, accompanied by Richard E. Etheridge, we again crossed the
+isthmus several times in order to gather ecological data in the wet
+season, and studied especially hylid frogs, most of which had not been
+seen in the dry season. Accompanied by Jerome B. Tulecke and John
+Wellman, I collected again in the isthmus in July, 1958, between Salina
+Cruz and Tehuantepec, and between Coatzacoalcos and Cosoleacaque. In
+March and April, 1959, I collected at Ciudad Aleman. Nearly 1200
+specimens of 30 species of amphibians were thus collected in the
+Isthmus of Tehuantepec; all specimens are now in the Museum of Zoology
+at the University of Michigan. Of other species known from the isthmus,
+I have had field experience with all but one (_Bolitoglossa
+veracrucis_) in other parts of Mexico.
+
+
+_Sources of Material_
+
+There are in museum collections nearly 3000 specimens of amphibians
+with reliable data from the Isthmus of Tehuantepec. Among the first
+herpetological specimens collected in the isthmian region are those
+assembled by Francis Sumichrast in the 1870's from the vicinity of
+Santa Efigenia and Tapanatepec, Oaxaca. These specimens were sent to
+the United States National Museum and the Museum National d'Histoire
+Naturelle in Paris; many served as the types of new species: _Bufo
+canaliferus_ Cope, _Eleutherodactylus rugulosus_ Cope, _Syrrhophus
+leprus_ Cope, and _Hylella sumichrasti_ Brocchi. In 1911 Alexander G.
+Ruthven collected in the savanna country near Cuatotolapam, Veracruz;
+the report on his collections (1912) is the first dealing with the
+herpetofauna of a part of the isthmus. His specimens are in the
+collection of the University of Michigan Museum of Zoology. Norman
+Hartweg and James A. Oliver collected for the University of Michigan
+Museum of Zoology in the vicinity of Tehuantepec, Oaxaca, during the
+summer of 1936. The results of their work were published as an
+annotated list of species occurring on the Pacific slopes of the
+isthmus (1940). Hobart M. Smith collected in the vicinity of
+Tehuantepec in January, 1940; his specimens are in the United States
+National Museum. Specimens collected by Smith served as the types of
+_Eleutherodactylus avocalis_ Taylor and Smith and _Diaglena reticulata_
+Taylor. Walter W. Dalquest collected vertebrates for the University of
+Kansas in southern Veracruz in the winters of 1947 and 1948; he spent
+about six months on the Gulf lowlands of the isthmus, principally in
+the vicinity of Jesus Carranza. For the past two decades Thomas
+MacDougall, a resident of New York City, has spent his winters
+collecting biological specimens in southern Mexico. He makes his
+headquarters at Tehuantepec, but his compulsion to see the "back
+country" has taken him to many remote parts of southern Oaxaca. His
+earlier collections are in the American Museum of Natural History; the
+later ones are in the University of Illinois Museum of Natural History.
+
+Minor collections include those made by Matthew W. Stirling at San
+Lorenzo, Veracruz, February-April, 1946 (United States National
+Museum), by Fred G. Thompson on a trip across the isthmus in December,
+1955 (University of Michigan Museum of Zoology), by the University of
+Kansas Museum of Natural History field party under the direction of
+Rollin H. Baker at Tolosita, Oaxaca, and by David A. Langebartel and
+associates from southern Oaxaca in June, 1958 (University of Illinois
+Museum of Natural History).
+
+In the collections of the United States National Museum are several
+species of amphibians sent to the museum from Tehuantepec by Francis
+Sumichrast. These include _Bolitoglossa platydactyla_ (USNM 30305,
+30344-6, 30528), _Bolitoglossa rufescens_ (10042), _Chiropterotriton
+chiropterus_ (30347), _Lineatriton lineola_ (30353), _Parvimolge
+townsendi_ (30352), _Pseudoeurycea cephalica_ (30350), _Thorius
+pennatulus_ (30348-9), _Hyla miotympanum_ (30302-3), and _Hyla picta_
+(30304). Because of the poor condition of the specimens, determinations
+of those listed as _Bolitoglossa rufescens_ and _Pseudoeurycea
+cephalica_ are uncertain. With the exception of the _Bolitoglossa
+rufescens_, which is stated to have come from Santa Efigenia, all of
+these specimens are catalogued as having come from Tehuantepec. None of
+these species has since been recorded from the Pacific slopes of the
+isthmus; however, they all occur in the vicinity of Orizaba, Veracruz.
+Probably Sumichrast carried the specimens with him from Orizaba, his
+home before moving to Santa Efigenia, and shipped them from Tehuantepec
+to the United States National Museum. These species definitely should
+not be considered as inhabitants of the Pacific slopes of the Isthmus
+of Tehuantepec.
+
+
+
+
+DESCRIPTION OF THE ISTHMUS OF TEHUANTEPEC
+
+
+The Isthmus of Tehuantepec is a strip of land forming a low pass, which
+separates the mountain masses of Mexico proper from those of Central
+America, and at the same time provides a continuum of lowlands from the
+Gulf of Mexico to the Pacific Ocean. This topography combines with the
+climatic conditions to create extremely diverse environments, the
+distribution of which can be adequately understood only after an
+acquaintance with the topography and climate of the region.
+
+
+_Physiography_
+
+In east-central Oaxaca the mountain masses comprising the Sierra Madre
+Oriental and the Sierra del Sur terminate in a series of ranges--Sierra
+de Juarez, Sierra de los Mijes, and Sierra de Choapam. From lofty
+peaks, such as Cerro de Zempoaltepetl (3400 meters), the highlands
+diminish eastward to succeedingly lower ridges, until in the middle of
+the Isthmus of Tehuantepec the continental divide is about 250 meters
+above sea level. Eastward from this low divide the land rises to form
+the Sierra Madre de Chiapas, which is continuous with the highland
+masses of Guatemala.
+
+For the purposes of this description, the lowlands of the isthmus may
+be divided into three parts--the Gulf Coastal Plain, the central
+ridges, and the Pacific Coastal Plain, which in the isthmus is called
+the Plains of Tehuantepec (Figs. 1 and 2).
+
+The Gulf Coastal Plain is broad and fairly level near the coast, but
+rolling in the interior. The plain, throughout most of its length in
+the isthmus, is at least 75 kilometers wide. The majority of the region
+in the isthmus is drained by the Rio Coatzacoalcos, which flows in a
+northerly course to the Gulf of Mexico. The western part is drained by
+the Rio San Juan, the principal tributary of the Rio Papaloapan. Behind
+the coastal dunes are frequent, and sometimes large, lagoons.
+Immediately inland from Coatzacoalcos and along the lower stretches of
+the Rio Papaloapan are extensive marshes. Essentially the entire
+coastal plain, with the exception of the coastal dunes, consists of
+rich alluvial deposits.
+
+[Illustration: FIG. 1. Map of the Isthmus of Tehuantepec based on the
+American Geographical Society's "Map of Hispanic America on the Scale
+of 1:1,000,000."
+
+The localities shown are numbered in the gazetteer; the numerical
+sequence of localities is an arrangement whereby north takes precedence
+over south and west over east. 1. Alvarado. 2. Lerdo de Tejada. 3.
+Tlacotalpan. 4. Tula. 5. Tecolapan. 6. Amatitlan. 7. Cosamaloapan. 8.
+Chacaltianguis. 9. Novillero. 10. Ciudad Aleman. 11. Papaloapan. 12.
+Tuxtepec. 13. Cuatotolapam. 14. Hueyapan. 15. Berta. 16. Coatzacoalcos.
+17. Ayentes. 18. Rio de las Playas. 19. Cosoleacaque. 20. Minatitlan.
+21. Acayucan. 22. Aquilera. 23. San Lorenzo. 24. Naranja. 25. Suchil.
+26. Jesus Carranza. 27. La Oaxaquena. 28. Ubero. 29. Donaji. 30.
+Tolosita. 31. El Modelo. 32. Sarabia, 33. Guichicovi. 34. La Princesa.
+35. Santa Maria Chimalapa. 36. Matias Romero. 37. Santo Domingo Petapa.
+38. El Barrio. 39. Palmar. 40. Chivela. 41. Santiago Chivela. 42.
+Nizanda. 43. Agua Caliente. 44. Portillo Los Nanches. 45. Ixtepec. 46.
+La Ventosa. 47. Zanatepec. 48. Union Hidalgo. 49. Tres Cruces. 50.
+Juchitan. 51. Escurano. 52. Salazar. 53. Santa Efigenia. 54.
+Tequisistlan. 55. Cerro de Quiengola. 56. San Pablo. 57. Mixtequilla.
+58. Tapanatepec. 59. Zarzamora. 60. Limon. 61. Tehuantepec. 62.
+Bisilana. 63. Santa Lucia. 64. Cerro de Arenal. 65. Cerro de San Pedro.
+66. La Concepcion. 67. Tenango. 68. San Antonio. 69. Huilotepec. 70.
+Salina Cruz.]
+
+[Illustration: FIG. 2. Topographic profile of the Isthmus of
+Tehuantepec showing major localities along the Trans-isthmian Highway
+and major types of vegetation. Vertical exaggeration approximately 165
+times.]
+
+The central ridges extend from the Rio Jaltepec southward to within 40
+kilometers of the Pacific coast. It is in this area that the continuity
+of the high ridges and volcanic peaks, which extend nearly the entire
+length of the Americas, is interrupted at a point almost directly in
+line with the shortest distance between the two oceans. The northern
+part of this central region consists of hills dissected by tributaries
+of the Rio Coatzacoalcos; the principal ones from north to south
+are--Rio Jaltepec, Rio Tortuguero, Rio Sarabia, and Rio Malatengo. The
+plains of Chivela are south of these rivers and lie at an elevation of
+about 200 meters; at the southern edge of these plains a range of hills
+rises to 250 to 400 meters above sea level. These hills drop abruptly
+to the Plains of Tehuantepec. In the northern and central parts of this
+central region the rocks are granitic; the hills to the south of the
+Plains of Chivela are limestone.
+
+The Pacific Coastal Plain or Plains of Tehuantepec have a maximum width
+of about 30 kilometers. From the base of the hills at an elevation of
+about 75 meters the plains slope gradually to the sea. To the west of
+the Rio Tehuantepec and to the east of the Plains of Tehuantepec at the
+base of the Sierra Madre de Chiapas, the coastal plain becomes much
+narrower; in these places the continuity of the plain is frequently
+interrupted by low north-south ridges extending outward from the
+mountains or by isolated hills. The soil is poor, varying from volcanic
+rock to gravel and sand.
+
+
+_Climate_
+
+The prevailing winds are from the north across the Gulf of Mexico.
+These moisture-laden winds precipitate most of their moisture north of
+the central ridges. This results in high rainfall on the northern
+slopes and Gulf Coastal Plain and relatively little rainfall on the
+southern slopes and the Pacific Coastal Plain. Precipitation is cyclic;
+there is a marked wet and a dry season throughout the region, but this
+is most noticeable on the Pacific lowlands (Fig. 3). At Salina Cruz on
+the Pacific Ocean the average annual rainfall is 1040 mm. (Contreras,
+1942); of this amount, only 15 mm. falls from November through April.
+On the Gulf Coastal Plain (Minatitlan station) the average annual
+rainfall is 3085 mm. In this region the driest months are February
+through May, during which time 236 mm. of rain falls. At Salina Cruz
+the wettest month is June; at Minatitlan it is September. There is
+little variation in temperature throughout the isthmus; the average
+annual temperature at Salina Cruz is 26.6 deg. C.; that at Minatitlan is
+26.2 deg. C. During the winter when masses of air from the arctic move
+southward into the Great Plains of the United States, cool winds blow
+across the isthmus. These are usually accompanied by overcast sky and
+sometimes a slight amount of precipitation. These "nortes" may cause a
+drop in temperature of about six to eight degrees in a few hours.
+
+[Illustration: FIG. 3. Climatographs for Minatitlan, Veracruz, and
+Salina Cruz, Oaxaca, based on data given by Contreras (1942). Plotted
+points are for mean monthly temperatures and rainfall; months are
+indicated by numbers.]
+
+
+_Vegetation_
+
+The topography and climate combine to produce drastically different
+types of climax vegetation on the northern and southern lowlands of the
+isthmus. The picture is somewhat complicated by the savannas on the
+Gulf Coastal Plain, which, as will be shown later, are dependent upon
+edaphic features more than climatic conditions. The following brief
+account of the vegetation in the Isthmus of Tehuantepec is based on
+data provided by Williams (1939) and Goldman (1951), supplemented by
+personal observations. The purpose of this description is not to
+analyze the flora of the isthmus, but to give the reader a picture of
+this aspect of the biota of the major environments with which I shall
+be concerned in the ensuing discourse on the amphibians of the region.
+The three divisions of the isthmus recognized in the account of the
+physiography serve equally well in describing the vegetation. Those
+divisions are as follows:
+
+Gulf Lowlands
+
+On the lowlands north of the continental divide and extending to the
+Gulf of Mexico are three major types of vegetation--tropical
+rainforest, arid tropical scrub forest, and savanna. Aside from these,
+there are marshes and lagoons near the coast.
+
+On the coastal dunes there are thickets of sea grape, patches of
+_Cenchrus_, and clumps or scattered _Opuntia_. The lagoons are bordered
+by mangrove thickets made up primarily of _Lonchocarpus hondurensis_.
+In the marshes along the lower Rio Coatzacoalcos and Rio Papaloapan the
+tall tough grass, _Gynerium sagittatum_, is common.
+
+According to Beard (1953: 291) the development of savanna vegetation is
+dependent upon soil, topography, and drainage. Level regions having
+permeable soil horizons lying on top of an impermeable horizon provide
+poor drainage. In most savanna regions in the Americas the grasslands
+become waterlogged or even partly flooded during the rainy season and
+desiccated in the dry season. Many ecologists and phytogeographers have
+postulated that savannas are either man made or are examples of a fire
+climax. Beard (_op. cit._: 203) provided multitudinous evidence that
+the association of savanna vegetation and certain types of edaphic and
+topographic conditions was so strongly marked that grassland is the
+natural vegetation in these areas.
+
+Savannas are scattered through southern Veracruz eastward to British
+Honduras. These usually are grasslands having scattered trees or clumps
+of trees around depressions, which may contain water throughout the
+year (Pl. 1, fig. 1). According to Williams (_op. cit._), the most
+common trees in the savannas in southern Veracruz are _Ceiba
+pentandra_, _Chlorophora tinctoria_, and _Byrsonima crassifolia_.
+
+Lying in a rain shadow cast by the Tuxtlas and on sandy and
+well-drained soils is a dense xerophytic forest. The crown of this
+deciduous forest usually is little more than ten to twelve meters above
+the ground (Pl. 1, fig. 2). Conspicuous trees in this scrub forest are
+_Acacia cornigera_, _Bauhinia latifolia_, _Calliandra bijuga_, _Cassia
+laevigata_, _Guazuma ulmifolia_, and various species of _Bursera_.
+
+The most extensive type of vegetation on the Gulf Coastal Plain is a
+tall evergreen forest resembling tropical rainforest. Although this
+forest is made up of many species of trees that are characteristic of
+true rainforest, the forest on the Gulf Coastal Plain cannot be
+classified as true rainforest, neither by the climatic conditions, nor
+the structure of the forest. The seasonal variation in rainfall
+probably is the chief factor in hindering the development of a
+rainforest climax vegetation. Usually a minimum of 65 mm. of rainfall
+each month is considered essential for the development of true
+rainforest. At Minatitlan the average rainfall for March (39 mm.) and
+April (36 mm.) is far below this minimum. Structurally, this forest has
+a crown about 30-35 meters above the ground but individual trees rising
+five meters or more above the crown (Pl. 2, figs. 1-2). There is no
+clear stratification within the forest; in many parts of it there are
+dense growths of bushes, small trees, and palms. The forest on the Gulf
+Coastal Plain, therefore, most properly might be referred to as a
+quasi-rainforest, a term that has been applied to other such forests in
+tropical America.
+
+Among the abundant and dominant trees in this forest are _Swietenia
+macrophylla_, _Calophyllum brasiliense_, _Achras zapota_, _Ceiba
+pentandra_, _Castilla elastica_, _Cedrela mexicana_, _Tabebuia
+Donnell-Smithi_, _Calocarpum mammosum_, _Bombax ellipticum_, and a
+variety of _Ficus_. Epiphytes and Ilianas are abundant.
+
+Central Ridges
+
+The vegetation of the central ridges of the isthmus is, for the most
+part, transitional between the tall rainforest of the Gulf Coastal
+Plain and the low xerophytic scrub forest of the semi-arid Pacific
+Coastal Plain. On the northern slopes of the ridges the rainforest is
+more poorly developed than on the plains to the north. Many of the same
+species of trees are present, including _Ceiba pentandra_, _Cedrela
+mexicana_, _Swietenia macrophylla_, and _Ficus_ sp.; nevertheless,
+these seldom are as large as members of the same species in the forest
+on the plains. Other species present on the forested slopes include
+_Tabebuia Donnell-Smithi_, _Zanthoxylum melanostictum_, _Pithecolobium
+arboreum_, and a species of _Pterocarpus_. The structure of this forest
+differs from that on the Gulf Coastal Plain in that there is no
+continuous upper canopy and there is a dense undergrowth (Pl. 3, fig.
+1). This type of forest extends from Mogone southward to about Matias
+Romero.
+
+In the vicinity of Matias Romero open pine-oak forest (_Pinus caribaea_
+and _Quercus_ sp.) is found on some ridges as low as 250 meters above
+sea level.
+
+On the Plains of Chivela in the southern part of the central region
+the vegetation takes on a semi-arid appearance, especially in a savanna
+on the plains. Clumps of small trees and bushes, consisting of _Croton
+nivea_, _Cordia cana_, _Jacquinia aurantiaca_, _Calycophyllum
+candidissimum_, and _Cassia emarginata_, are scattered on a grassy
+plain, from which rise widely-spaced palms of an unknown species (Pl.
+3, fig. 2).
+
+Pacific Coastal Plain
+
+The vegetation of the Pacific lowlands definitely is semi-arid in
+character. Most of the trees are deciduous, thorny, and short. During
+the dry season the landscape presents a barren appearance, but shortly
+after the first summer rains dense green foliage appears (Pl. 4, figs.
+1 and 2). Between Juchitan and La Ventosa few trees are more than two
+meters high (Pl. 5, fig. 1). In many areas the trees and bushes form an
+almost impenetrable tangle, whereas on especially rocky soils or on
+slopes those plants are more widely spaced. Abundant and widespread
+species of trees on the Plains of Tehuantepec include _Acacia
+cymbispina_, _Prosopis chilensis_, _Caesalpinia coriaria_, _Caesalpinia
+eriostachys_, _Celtis iguanaea_, _Cordia brevispicata_, _Jatropha
+aconitifolia_, and _Crescentia alata_.
+
+Montane Vegetation
+
+In order to illustrate the interruption of subtropical and temperate
+types of vegetation by the lowlands of the Isthmus of Tehuantepec, it
+is necessary to digress for a moment from the isthmus and consider the
+types of vegetation present on the adjacent highlands. On the higher
+peaks, such as Cerro de Zempoaltepetl, above about 2500 meters is fir
+forest (_Abies religiosa_); lower on the slopes are extensive pine
+forests, which on some slopes are mixed with oak or replaced entirely
+by oaks. Subtropical cloud forest, characterized by relatively cool
+temperatures and high humidity, is found at elevations usually between
+1000 and 1800 meters on the windward slopes of the Sierra Madre
+Oriental in Veracruz and northern Oaxaca and on the northern and
+southern slopes of the Chiapan-Guatemalan Highlands. None of these
+forest types is continuous across the Isthmus of Tehuantepec.
+
+
+_The Sierra de los Tuxtlas_
+
+Although actually located in the region of the Isthmus of Tehuantepec,
+the Sierra de los Tuxtlas, because of its isolated position, need not
+be considered in great detail in analyzing the distribution of animals
+inhabiting the lowlands of the isthmus. Nevertheless because some
+species living in the highlands adjacent to the isthmus also live in
+the Tuxtlas, this range is briefly described here. The Sierra de los
+Tuxtlas is a range of volcanos lying near the Gulf Coast in southern
+Veracruz between the mouths of the Rio Papaloapan and the Rio
+Coatzacoalcos. Volcan San Martin, the highest peak, rises above 1800
+meters. This range of volcanos is surrounded by lowlands, which
+immediately to the south and west are covered with savanna and in
+places by scrub forest. The luxuriant nature of the vegetation on these
+volcanos indicates that this range receives much more rainfall than the
+surrounding lowlands. Especially on the northern slopes, tropical
+rainforest is well developed; this is replaced at about 1200 meters by
+cloud forest. The southern and western slopes are drier, for the lower
+slopes are covered with a scrubby, but evergreen, forest.
+
+Detailed comments on the herpetofauna of the Tuxtlas have been omitted
+purposefully, for the reptiles and amphibians of the region currently
+are being studied by Douglas Robinson.
+
+
+
+
+GAZETTEER
+
+
+The following localities are those referred to in the text. The name of
+the locality (listed alphabetically by states) is followed by latitude,
+longitude, elevation, general description (town, ranch, etc.), and
+general type of habitat. Unless otherwise noted, distances are
+straight-line (airline) distances in kilometers. The localities have
+been plotted from the American Geographical Society's "Map of Hispanic
+America on the Scale of 1:1,000,000" (Millionth Map). Numbers in
+brackets identify the position of a locality on the accompanying map
+(Fig. 1).
+
+
+_Oaxaca_
+
+     Agua Caliente.--Lat. 16 deg. 38'; long. 94 deg. 48'; elev. 140 m. A
+     hot spring, 6.9 km. north of La Ventosa on the
+     Trans-isthmian Highway; arid scrub forest [43].
+
+     Arenal, Cerro de.--Lat. 16 deg. 18'; long. 95 deg. 32'; elev. 925 m.
+     (crest). A ridge northeast of Tenango; scrub forest on
+     slopes and pine-oak forest on top [64].
+
+     Barrio, El.--Lat. 16 deg. 38'; long. 95 deg. 07'; elev. 314 m. A
+     village about 10 kilometers southwest of Matias Romero;
+     transition between scrub forest and broadleaf hardwood
+     forest [38].
+
+     Bisilana.--Lat. 16 deg. 20'; long. 95 deg. 13'; elev. 35 m. A place
+     name for a former ranch at the edge of Tehuantepec; open
+     arid scrub forest [62].
+
+     Chivela.--Lat. 16 deg. 20'; long. 95 deg. 01'; elev. 195 m. A
+     village on the Trans-isthmian Railroad, 26 kilometers by
+     rail south of Matias Romero and on the western edge of the
+     semi-arid Plains of Chivela [40].
+
+     Concepcion.--Lat. 16 deg. 17'; long. 95 deg. 29'; elev. 1200 m. A
+     ranch on the slopes of Cerro Arenal, east-northeast of
+     Tenango; dry pine-oak forest [66].
+
+     Coyol.--Exact position unknown; according to Smith and
+     Taylor (1950: 10), Coyol is "between San Antonio and Las
+     Cruces."
+
+     Donaji.--Lat. 17 deg. 13'; long. 95 deg. 02'; elev. 90 m. A village
+     at Km. 155 on the Trans-isthmian Highway; rainforest [29].
+
+     Escurano.--Lat. 16 deg. 25'; long. 95 deg. 27'; elev. 500 m. A ranch
+     about 25 kilometers west-northwest of Tehuantepec; arid
+     scrub forest [51].
+
+     Guichicovi, San Juan.--Lat. 16 deg. 58'; long. 95 deg. 06'; elev.
+     250 m. A village on the north slopes of the isthmus, 12
+     kilometers north-northwest of Matias Romero; cleared
+     hardwood forest and coffee plantations [33].
+
+     Huilotepec.--Lat. 16 deg. 14'; long. 95 deg. 09'; elev. 30 m. A
+     small village on the Rio Tehuantepec, 13 kilometers
+     south-southeast of Tehuantepec; open arid scrub forest [69].
+
+     Ixtepec.--Lat. 16 deg. 34'; long. 95 deg. 06'; elev. 60 m. A town
+     and railroad junction on the northwestern edge of the Plains
+     of Tehuantepec; arid scrub forest [45].
+
+     Juchitan.--Lat. 16 deg. 26'; long. 95 deg. 02'; elev. 15 m. A town
+     on the Plains of Tehuantepec, 22 kilometers by road
+     east-northeast of Tehuantepec; arid scrub forest [50].
+
+     Limon.--Lat. 16 deg. 20'; long. 95 deg. 29'; elev. 600 m. A former
+     agrarian colony and now a small ranch about 27 kilometers
+     west of Tehuantepec; arid scrub forest [60].
+
+     Matias Romero.--Lat. 16 deg. 53'; long. 95 deg. 02'; elev. 200 m. A
+     town on the Trans-isthmian Highway and railroad in the hills
+     near the crest of the isthmus; broadleaf hardwood forest and
+     open pine-oak forest [36].
+
+     Mixtequilla.--Lat. 16 deg. 24'; long. 95 deg. 18'; elev. 40 m. A
+     village on the Rio Tehuantepec, northwest of Tehuantepec;
+     dense scrub forest [57].
+
+     Modelo, El.--Lat. 17 deg. 07'; long. 94 deg. 43'; elev. 200 m. An
+     old rubber plantation on the Rio Chalchijapa, a tributary to
+     the Rio Coatzacoalcos; rainforest [31].
+
+     Nanches, Portillo Los.--Lat. 16 deg. 35'; long. 95 deg. 37'; elev.
+     500 m. A place name, about 4 kilometers southeast of
+     Totolapilla; scrub forest [44].
+
+     Nizanda.--Lat. 16 deg. 42'; long. 95 deg. 02'; elev. 150 m. A
+     village on the Trans-isthmian Railroad between Chivela and
+     Ixtepec; dense scrub forest [42].
+
+     Nueva Raza.--Exact location unknown; according to Thomas
+     MacDougall, this locality is in the lowlands of northern
+     Oaxaca; rainforest.
+
+     Palmar.--Lat. 16 deg. 43'; long. 94 deg. 40'; elev. 300 m. A small
+     ranch on the west base of Cerro Atravesado; scrub forest
+     [39].
+
+     Papaloapan.--Lat. 18 deg. 11'; long. 96 deg. 06'; elev. 25 m. A
+     small village on the Rio Papaloapan in northern Oaxaca; low
+     evergreen forest and savanna [11].
+
+     Princesa, La.--Lat. 16 deg. 56'; long. 95 deg. 02'; elev. 150 m. A
+     ranch on the northern slopes of the isthmus, 6 kilometers by
+     road north of Matias Romero; poorly developed rainforest
+     [34].
+
+     Quiengola, Cerro de.--Lat. 16 deg. 24'; long. 95 deg. 22'; elev. 900
+     m. (crest). A hill 15 kilometers west-northwest of
+     Tehuantepec; dense scrub forest on slopes and scattered
+     pines on top [55].
+
+     Salazar.--Lat. 16 deg. 25'; long. 95 deg. 20'; elev. 45 m. A ranch
+     on the Rio Tehuantepec, northwest of Tehuantepec; dense
+     scrub forest [52].
+
+     Salina Cruz.--Lat. 16 deg. 10'; long. 95 deg. 12'; sea level. A port
+     on the Golfo de Tehuantepec; open arid scrub forest [70].
+     Collections were made in the vicinity of the town and in the
+     open scrub forest 2.4 kilometers north at an elevation of 20
+     meters.
+
+     San Antonio.--Lat. 16 deg. 15'; long. 95 deg. 22'; elev. 40 m. A
+     ranch about 25 kilometers west-southwest of Tehuantepec;
+     arid scrub forest [68].
+
+     San Pablo.--Lat. 16 deg. 24'; long. 95 deg. 18'; elev. 40 m. A ranch
+     on the Rio Tehuantepec, northwest of Tehuantepec; dense
+     scrub forest [56]. Cerro San Pablo probably is the hill
+     north of this ranch; this is shown on some maps as Cerro de
+     los Amates.
+
+     San Pedro, Cerro de.--Lat. 16 deg. 18'; long. 95 deg. 28'; elev.
+     about 1100 m. (crest). A ridge about 24 kilometers west of
+     Tehuantepec and east of Cerro Arenal; scrub forest on slopes
+     and pine-oak forest on top [65].
+
+     Santa Efigenia.--Lat. 16 deg. 25'; long. 94 deg. 13'; elev. 500 m. A
+     ranch on the southern slopes of the Sierra Madre de Chiapas,
+     8 kilometers north-northwest of Tapanatepec; scrub forest.
+     Former home of Francis Sumichrast [53].
+
+     Santa Lucia.--Lat. 16 deg. 18'; long. 95 deg. 28'; elev. 800 m. A
+     place name for a former ranch on the east slopes of Cerro
+     Arenal; scrub forest [63].
+
+     Santa Maria Chimalapa.--Lat. 16 deg. 55'; long. 94 deg. 42'; elev.
+     296 m. A village on the Rio de los Milagros, a tributary to
+     the Rio Coatzacoalcos; rainforest [35].
+
+     Santiago Chivela.--Lat. 16 deg. 42'; long. 94 deg. 53'; elev. 200 m.
+     A village on the Trans-isthmian Highway, 13.4 kilometers by
+     road south of Matias Romero; dry, grassy plains and
+     scattered clumps of scrubby trees and palms [41].
+     Collections were made in the vicinity of the village and at
+     a rocky stream, 11 kilometers south on the Trans-isthmian
+     Highway at an elevation of 230 m.
+
+     Santo Domingo (Petapa).--Lat. 16 deg. 50'; long. 95 deg. 08'; elev.
+     225 m. A village about 13 kilometers west-southwest of
+     Matias Romero; semi-arid scrub forest [37].
+
+     Sarabia.--Lat. 17 deg. 04'; long. 95 deg. 02'; elev. 100 m. A
+     village 25 kilometers north of Matias Romero on the
+     Trans-isthmian Highway; rainforest [32]. Collections were
+     made in the vicinity of the village and in the rainforest
+     along the Rio Sarabia, 5 kilometers north of the village at
+     an elevation of 80 meters.
+
+     Tapanatepec.--Lat. 16 deg. 32'; long. 94 deg. 12'; elev. 90 m. A
+     town on the Pan-American Highway on the lower slopes of the
+     Sierra Madre de Chiapas; dense scrub forest [58].
+
+     Tehuantepec.--Lat. 16 deg. 20'; long. 95 deg. 14'; elev. 35 m. A
+     large town on the Plains of Tehuantepec; scrub forest [61].
+     Collections were made in the vicinity of the town and in the
+     dense scrub forest 8.6 kilometers west at an elevation of 85
+     meters and 14 kilometers west at an elevation of 120 meters.
+
+     Tenango.--Lat. 16 deg. 16'; long. 95 deg. 30'; elev. 1100 m. A town
+     in the mountains about 40 kilometers west-southwest of
+     Tehuantepec; scrub forest [67].
+
+     Tequisistlan.--Lat. 16 deg. 24'; long. 95 deg. 37'; elev. 190 m. A
+     village in the valley of the Rio Tequisistlan, a tributary
+     to the Rio Tehuantepec; dense scrub forest [54]. Most
+     collections were made about one kilometer north of the
+     village where the Pan-American Highway crosses the Rio
+     Tequisistlan.
+
+     Tolosita.--Lat. 17 deg. 12'; long. 95 deg. 03'; elev. 80 m. A
+     village on the Rio Tortuguero near the Trans-isthmian
+     Highway; rainforest [30].
+
+     Tres Cruces.--Lat. 16 deg. 26'; long. 95 deg. 51'; elev. 750 m. A
+     ranch near the Pan-American Highway, 70 kilometers by road
+     west-northwest of Tehuantepec; dense scrub forest [49].
+
+     Tuxtepec--Lat. 18 deg. 06'; long. 96 deg. 05'; elev. 80 m. A town on
+     the Rio Papaloapan in northern Oaxaca; low evergreen forest
+     [12].
+
+     Ubero.--Lat. 17 deg. 18'; long. 95 deg. 00'; elev. 80 m. A lumber
+     camp and railroad station, 8.5 kilometers south of the Rio
+     Jaltepec on the Trans-isthmian Highway; rainforest [28].
+
+     Union Hidalgo.--Lat. 16 deg. 27'; long. 94 deg. 48'; elev. 7 m. A
+     village on the railroad, 20 kilometers east-northeast of
+     Juchitan; open scrub forest [48].
+
+     Ventosa, La.--Lat. 16 deg. 30'; long. 94 deg. 51'; elev. 25 m. A
+     village at the junction of the Pan-American and
+     Trans-isthmian highways; open scrub forest [46].
+
+     Zanatepec.--Lat. 16 deg. 28'; long. 94 deg. 22'; elev. 80 m. A
+     village on the Pan-American Highway at the eastern edge of
+     the Plains of Tehuantepec; dense scrub forest [47]. Most
+     collections were made in the scrub forest 5 to 8 kilometers
+     west-northwest of the village.
+
+     Zarzamora.--Lat. 16 deg. 21'; long. 95 deg. 48'; elev. 800 m. A
+     ranch between La Reforma (16 kilometers west of
+     Tequisistlan) and Santa Maria Ecatepec; scrub forest with
+     oaks on higher ridges [59].
+
+
+_Veracruz_
+
+     Acayucan.--Lat. 17 deg. 57'; long. 94 deg. 55'; elev. 160 m. A large
+     town on the Trans-isthmian Highway; rainforest [21].
+     Collections were made in the vicinity of the town, but
+     principally at Rancho Las Hojitas, 7 kilometers northwest of
+     town at an elevation of 150 meters.
+
+     Alvarado.--Lat. 18 deg. 47'; long. 95 deg. 47'; sea level. A fishing
+     village at the mouth of the Rio Papaloapan; coastal dunes
+     and marshes [1]. Most collections were made 1-3 kilometers
+     southeast of the village in marshes on the leeward side of
+     the coastal dunes.
+
+     Amatitlan.--Lat. 18 deg. 26'; long. 95 deg. 45'; elev. 4 m. A
+     village on the bank of the Rio Papaloapan; savanna and sugar
+     plantations [6].
+
+     Aquilera.--Lat. 17 deg. 48'; long. 95 deg. 01'; elev. 150 m. A
+     village 21 kilometers southwest of Acayucan on the
+     Trans-isthmian Highway; rainforest [22].
+
+     Ayentes.--Lat. 18 deg. 10'; long. 94 deg. 26'; elev. 2 m. A railroad
+     station on the east bank of the Rio Coatzacoalcos, across
+     the river from the city of Coatzacoalcos; scrub forest and
+     marshes [17].
+
+     Berta.--Lat. 18 deg. 07'; long. 94 deg. 27'; elev. 5 m. A ranch just
+     south of Coatzacoalcos; scrub and low evergreen forest [15].
+
+     Chacaltianguis.--Lat. 18 deg. 18'; long. 95 deg. 52'; elev. 5 m. A
+     village on the Rio Papaloapan; savanna [8].
+
+     Ciudad Aleman.--Lat. 18 deg. 13'; long. 96 deg. 07'; elev. 30 m. A
+     new government town, headquarters of the Comision del
+     Papaloapan; scrub and low evergreen forest [10].
+
+     Coatzacoalcos (formerly Puerto Mexico).--Lat. 18 deg. 10'; long.
+     94 deg. 27'; elev. 2 m. A seaport at the mouth of the Rio
+     Coatzacoalcos; scrub on coastal dunes; marshes and low
+     evergreen forest inland [16]. Most collections are from the
+     forest-savanna ecotone, 8 kilometers southwest of town.
+
+     Cosamaloapan.--Lat. 18 deg. 22'; long. 95 deg. 50'; elev. 4 m. An
+     agricultural town on the Rio Papaloapan; savanna and sugar
+     plantations [7].
+
+     Cosoleacaque.--Lat. 17 deg. 59'; long. 94 deg. 38'; elev. 55 m. A
+     village 8 kilometers by road west of Minatitlan; savanna
+     [19].
+
+     Cuatotolapam.--Lat. 18 deg. 08'; long. 95 deg. 16'; elev. 13 m. A
+     village on the Trans-isthmian Railroad; savanna and low
+     evergreen forest along streams [13].
+
+     Hueyapan.--Lat. 18 deg. 08'; long. 19 deg. 09'; elev. 85 m. A town
+     32 kilometers by road northwest of Acayucan; savanna and low
+     evergreen forest [14]. Collections were made in the vicinity
+     of the town and from forest 10 kilometers southeast of town
+     at an elevation of 135 meters.
+
+     Jesus Carranza (formerly Santa Lucrecia).--Lat. 17 deg. 27';
+     long. 95 deg. 02'; elev. 80 m. A town and railroad junction in
+     the middle of the isthmus; rainforest [26]. Most of
+     Dalquest's specimens came from varying distances from Jesus
+     Carranza along the Rio Coatzacoalcos and its tributaries.
+
+     Minatitlan.--Lat. 17 deg. 58'; long. 94 deg. 32'; elev. 15 m. An oil
+     refinery center on the Rio Coatzacoalcos; savanna [20].
+
+     Naranjo.--Lat. 17 deg. 35'; long. 95 deg. 07'; elev. 100 m. A
+     village on the Trans-isthmian Highway, 45 kilometers south
+     of Acayucan; rainforest and palm forest [24].
+
+     Novillero.--Lat. 18 deg. 16'; long. 95 deg. 59'; elev. 10 m. A
+     village on the Rio Papaloapan; scrub forest and grassland
+     [9].
+
+     Oaxaquena, La.--Lat. 17 deg. 26'; long. 94 deg. 53'; elev. 80 m. A
+     hacienda on the Rio Coatzacoalcos about 12 kilometers east
+     of Jesus Carranza; rainforest [27].
+
+     Playas, Rio de las.--Lat. 18 deg. 08'; long. 94 deg. 07'; elev. 3 m.
+     The river (sometimes known as the Rio Tonola) forming the
+     boundary between the states of Veracruz and Tabasco;
+     rainforest [18].
+
+     San Lorenzo.--Lat. 17 deg. 44'; long. 94 deg. 42'; elev. 25 m. A
+     village on the Rio Chiquito, about 30 kilometers southeast
+     of Acayucan; rainforest [23].
+
+     Suchil.--Lat. 17 deg. 31'; long. 95 deg. 03'; elev. 40 m. A village
+     on the Trans-isthmian Railroad, about 10 kilometers north of
+     Jesus Carranza; rainforest [25].
+
+     Tecolapan.--Lat. 18 deg. 24'; long. 95 deg. 18'; elev. 275 m. A
+     village on a small river of the same name in the western
+     foothills of Los Tuxtlas; rainforest [5].
+
+     Tejada, Lerdo de.--Lat. 18 deg. 37'; long. 95 deg. 31'; elev. 60 m.
+     An agricultural village, 35 kilometers by road
+     east-southeast of Alvarado; scrub forest, marshes, and sugar
+     plantations [2]. Collections were made in a marsh, 5
+     kilometers west-northwest of the village.
+
+     Tlacotalpan.--Lat. 18 deg. 37'; long. 95 deg. 42'; elev. 3 m. A town
+     at the confluence of the Rio San Juan and Rio Papaloapan;
+     marshes and sugar plantations [3].
+
+     Tula.--Lat. 18 deg. 36'; long. 95 deg. 22'; elev. 150 m. A village
+     near the western base of Los Tuxtlas; low evergreen forest
+     and marshes [4]. Collections were made in a marsh 3
+     kilometers northwest of the village.
+
+
+
+
+THE AMPHIBIAN FAUNA OF THE LOWLANDS
+
+
+In presenting an account of the amphibian fauna of the lowlands of the
+Isthmus of Tehuantepec three items must be considered:
+
+     1. The composition of the fauna.
+
+     2. The ecology of the fauna.
+
+     3. The distribution of the fauna.
+
+These items, together with similar data concerning the amphibians of
+the adjacent highlands, will form the basis for the subsequent
+discussion of the establishment of present patterns of distribution in
+the isthmian region.
+
+
+_Composition of the Fauna_
+
+The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 36 species definitely recorded from the area. These include
+one genus and species of caecilian, one genus, including three species
+of salamanders, and 14 genera and 32 species of anurans.
+
+In comparison with the known amphibian fauna of the forested and
+savanna portions of El Peten, Guatemala (Stuart, 1935 and 1958), we
+find that there are more species recorded from the isthmus than from El
+Peten. Stuart found only 20 species of amphibians in both forest and
+savanna habitats in El Peten. Of the 36 species of amphibians known
+from the isthmus, 28 occur on the Gulf lowlands and live in forest or
+savanna habitats.
+
+The geographic position of the isthmus with regard to major faunal
+areas in Middle America, and the diversity of the environment are
+important factors in understanding the presence of a large number of
+species of amphibians in the isthmus. The large number of species
+probably is a reflection of the diversity of the environment; this
+diversity is the result of fluctuation of climate, and thus
+environments, in the not too distant past. In no individual habitat,
+such as rainforest, savanna, or scrub forest, does the number of
+species approach the total for the region.
+
+
+_Ecology of the Fauna_
+
+In the preceding section on the description of the Isthmus of
+Tehuantepec I have outlined the major environments in the region. With
+respect to the distribution of amphibians we may recognize three major
+environments in the isthmus--rainforest, semi-arid scrub forest, and
+savanna. Each of these has varying combinations of physical and biotic
+factors that are important in the ecology of amphibians. Because of the
+importance of moisture, not only for the maintenance of life in these
+animals, but in most species their dependence on water for breeding
+purposes, this environmental factor is considered the most significant
+in the ecological distribution of amphibians. A second factor is the
+availability of necessary shelter, especially aestivation sites. These
+factors will be compared in the three major environments in the region.
+
+Moisture is present in the environment in the form of free water or
+atmospheric moisture. With respect to the latter, it is well known that
+dense shaded forests have a considerably higher relative humidity than
+do open plains or areas with only scattered trees. Thus, the
+rainforests of the isthmus are characterized by a much higher relative
+humidity than are the savannas or semi-arid scrub forests. Although
+with regard to rainfall there is a pronounced dry season in the regions
+supporting rainforest, there still remains considerable atmospheric
+moisture in this environment throughout the year. The dense foliage
+provides shade and protection from desiccating effects of wind and
+sunlight; furthermore the foliage contributes moisture by
+transpiration. The deep alluvial soils mixed with large quantities of
+organic matter (decaying leaves and rotting logs) maintain considerable
+quantities of moisture.
+
+Conversely, the savannas and scrub forests have little atmospheric
+moisture during the dry season. In the former habitat there are few
+trees to provide shade or moisture through transpiration; in the latter
+most of the trees lose their leaves during the dry season. Thus, these
+environments are desiccated by the dry winds and direct sunlight.
+Furthermore, the soils in these environments become dry and caked.
+There is little or no terrestrial matter to hold moisture.
+
+Free water in these environments is present in a variety of forms at
+different times of the year. During the dry season the more extensive
+marshes in the savannas persist; many ponds and most of the streams in
+the rainforest are permanent throughout the year. In the scrub forest
+all except the largest streams become dry during the dry season, and no
+ponds exist through the dry season. With the advent of the first heavy
+summer rains the stream beds fill with water, marshes expand, and many
+depressions become ponds (Pl. 5, fig. 2). At this time the amount of
+free water in the scrub forests and savannas greatly increases, much
+more so than that in the rainforests.
+
+Environments are vertically stratified in the rainforests. There is the
+deep alluvial soil, the ground litter of leaves and decaying logs, the
+low bushes and small trees, and finally the tall trees of the forest.
+Each of these provides certain types of shelter for amphibians. The
+moist soil and litter on the forest floor is an important microhabitat
+for fossorial and strictly terrestrial species. The dense foliage of
+the trees, tree holes, and bromeliads growing on the trees provide
+shelter for arboreal species. Arboreal and terrestrial bromeliads and
+the terrestrial elephant-ear plants (_Xanthosoma_) contain water in the
+axils of their leaves throughout the year and thus provide an important
+habitat for amphibians. The low, spiny, deciduous trees of the scrub
+forest and the grasses and scattered trees in the savannas provide
+little shelter. In the savannas there are depressions, some of which
+contain water throughout the year; these are often surrounded by trees
+providing refugia for amphibians during the dry season. In the scrub
+forest many species congregate along streams and in moist stream beds
+during the dry season.
+
+Now that the important ecological factors of the major environments
+have been outlined, we may examine the local distribution of amphibians
+in each of these. Beginning with the rainforest, we find only one
+fossorial species, _Gymnopis mexicanus_. A large number of species are
+found on the forest floor; characteristic inhabitants of the leaf
+litter are: _Bufo valliceps_, _Eleutherodactylus rhodopis_,
+_Microbatrachylus pygmaeus_, and _Syrrhophus leprus_. Other terrestrial
+amphibians usually are not scattered throughout the rainforest, as are
+those named immediately above, but instead inhabit areas of forest
+adjacent to ponds or streams; these species include: _Bufo marinus_,
+_Eleutherodactylus natator_, _Eleutherodactylus rugulosus_,
+_Leptodactylus labialis_, _Leptodactylus melanonotus_, _Rana palmipes_
+and _Rana pipiens_. The most striking ecological assemblage of
+amphibians in the rainforest is the arboreal group of species,
+including:
+
+     _Bolitoglossa occidentalis_
+     _Bolitoglossa platydactyla_
+     _Eleutherodactylus alfredi_
+     _Hyla baudini_
+     _Hyla ebraccata_
+     _Hyla loquax_
+     _Hyla microcephala martini_
+     _Hyla picta_
+     _Phrynohyas modesta_
+     _Phrynohyas spilomma_
+     _Phyllomedusa callidryas taylori_
+
+In the savannas _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and
+_Gastrophryne usta_ are fossorial species. _Bufo marinus_,
+_Leptodactylus melanonotus_, _Leptodactylus labialis_, _Rana palmipes_,
+and _Rana pipiens_ are found in the vicinity of permanent water in the
+savannas. Although the savanna habitat does not provide the ecological
+conditions for the existence of an arboreal fauna, many arboreal
+species from the surrounding rainforest utilize the extensive marshes
+and ponds in the savannas for breeding purposes. Thus, _Hyla baudini_,
+_Hyla microcephala martini_, _Hyla picta_, and _Phrynohyas spilomma_
+have been found breeding in savannas. In parts of savannas where clumps
+of trees surround depressions containing water throughout the year,
+individuals of the species named above, together with _Hyla loquax_ and
+_Phyllomedusa callidryas taylori_, may not only breed, but remain
+throughout the year.
+
+In the semi-arid scrub forest the same fossorial species as exist in
+the savannas are found. Likewise, _Bufo marinus_, _Leptodactylus
+labialis_, _Leptodactylus melanonotus_, and _Rana pipiens_ are found
+near permanent water. Terrestrial species in this semi-arid environment
+include _Bufo canaliferus_, _Bufo coccifer_, _Bufo marmoreus_,
+_Syrrhophus pipilans_, and _Diaglena reticulata_. Of these, _Syrrhophus
+pipilans_ sometimes inhabits low trees and bushes; the others may be
+fossorial. The arboreal species in the scrub forest include _Hyla
+baudini_, _Hyla robertmertensi_, _Hyla staufferi_, and _Phyllomedusa
+dacnicolor_.
+
+_Eleutherodactylus rugulosus_ and _Hylella sumichrasti_ live along
+streams in the scrub forest. _Hylella sumichrasti_ lays its eggs in
+these streams.
+
+In comparing the ecological differences in the amphibian assemblages in
+the three major habitats, the most obvious difference is the great
+percentage of arboreal species in the rainforest as compared with
+savanna and scrub forest. Only four arboreal species are found in the
+scrub forest, none in the savannas, but eleven in the rainforest.
+Likewise, there is an absence of ground-dwelling forms in the arid
+habitats; in the latter the only terrestrial species are those that
+are found near water. A possible exception is _Syrrhophus pipilans_.
+
+From the above analysis of ecological distribution we may see that the
+rainforest provides a variety of habitats for amphibians and that these
+habitats are suitable for amphibian life throughout the year. On the
+other hand, the savannas and scrub forests are characterized by extreme
+conditions of desiccation, a factor of considerable importance in
+limiting the ecological distribution of amphibians. However, there
+still is a diversity of amphibians in these semi-arid environments.
+Obviously, these species are adapted in various ways for survival
+during the dry season, at which time environmental conditions are such
+that the animals cannot carry on their normal activities.
+
+Although there is not an abundance of data concerning the seasonal
+activity of the fauna, what is available shows some interesting
+correlations with the environments. During the dry season in the scrub
+forest there is essentially no amphibian activity; an occasional _Rana
+pipiens_ may be seen along a river, or a _Bufo marinus_ may be seen at
+night. In the rainforest the terrestrial-breeding amphibians are active
+during the dry season. _Eleutherodactylus rugulosus_ is found at night
+or by day along streams. _Eleutherodactylus rhodopis_,
+_Microbatrachylus pygmaeus_, and _Bufo valliceps_ are active during the
+day; these plus _Bolitoglossa occidentalis_, _Bolitoglossa
+platydactyla_, _Eleutherodactylus alfredi_, _Eleutherodactylus
+natator_, and an occasional _Hyla_ are active at night.
+
+With the onset of the heavy summer rains and the subsequent formation
+of breeding ponds, amphibian activity reaches a peak. This is
+especially noticeable in the semi-arid environments, where during the
+dry season there is little activity.
+
+Among the anurans in the isthmus the four species of
+_Eleutherodactylus_, the two species of _Syrrhophus_, and the one
+species of _Microbatrachylus_ are either known, or presumed, to lay
+eggs on the ground; these develop directly into small frogs. All of the
+other anurans deposit their eggs in water or attach them to objects
+over water (_Phyllomedusa_); these hatch into tadpoles, which later
+metamorphose into frogs. _Hylella sumichrasti_ is known to breed only
+in streams. All of the other species breed in ponds, but at times some
+species deposit their eggs in streams; in this last group are _Bufo
+valliceps_, _Bufo marmoreus_, _Phyllomedusa callidryas taylori_, and
+_Rana pipiens_.
+
+Although the ecological data are incomplete, they do show that
+ecological conditions differ greatly in the three major environments,
+different species of amphibians inhabit these environments, and that
+the fauna is ecologically diversified in each environment.
+
+
+_Distribution of the Fauna_
+
+Plotting the distributions of species of amphibians known to live in
+the lowlands of the Isthmus of Tehuantepec results in an array of
+geographic patterns. These may be analyzed with respect to those
+species that are restricted either to the Gulf lowlands or the Pacific
+lowlands, or those that occur on both the Gulf and Pacific lowlands.
+Furthermore, the distributions may be analyzed with respect to those
+species whose ranges extend from Mexico across the Isthmus of
+Tehuantepec into Central America, those that reach the isthmus from
+Central America but do not extend into Mexico proper, and those that
+reach the isthmus from Mexico but do not extend into Central America.
+It should be kept in mind that the following analysis is of the lowland
+inhabitants only. Species inhabiting the foothills and mountains will
+be discussed later.
+
+1. SPECIES RESTRICTED TO THE GULF LOWLANDS. Of the 36 species of
+amphibians recorded from the Isthmus of Tehuantepec, nine (25 per cent)
+are in this group. Four of these (_Eleutherodactylus alfredi_,
+_Syrrhophus leprus_, _Hyla loquax_, and _Hyla picta_) live in the Gulf
+lowlands to the east and to the west of the isthmus. Three others
+(_Hyla ebraccata_, _Hyla microcephala martini_ and _Phyllomedusa
+callidryas taylori_) are primarily Central American in their
+distribution and reach the northwestern limits of their ranges in the
+Gulf lowlands of the isthmus, whereas _Bolitoglossa platydactyla_ and
+_Eleutherodactylus natator_ reach the southern limits of their
+distributions in the isthmus.
+
+2. SPECIES RESTRICTED TO THE PACIFIC LOWLANDS. This group includes six
+species, or 17 per cent of the amphibian fauna of the isthmus. Two of
+these (_Bufo coccifer_ and _Syrrhophus pipilans_) range to the east and
+to the west of the isthmus on the Pacific lowlands. Two others (_Bufo
+canaliferus_ and _Hyla robertmertensi_) range from the isthmus into
+Central America, and _Diaglena reticulata_ and _Phyllomedusa
+dacnicolor_ range on the Pacific lowlands of Mexico southeastward to
+the isthmus.
+
+3. SPECIES THAT OCCUR ON THE PACIFIC AND GULF LOWLANDS. This group
+includes 19 species, or 53 per cent of the total amphibian fauna. Of
+these, nine species (25 per cent of the entire amphibian fauna) are
+widespread throughout the lowlands of Mexico and Central America; these
+are:
+
+     _Gymnopis mexicanus_
+     _Rhinophrynus dorsalis_
+     _Bufo marinus_
+     _Engystomops pustulosus_
+     _Leptodactylus labialis_
+     _Leptodactylus melanonotus_
+     _Hyla baudini_
+     _Hyla staufferi_
+     _Rana pipiens_
+
+Four species occur on the Gulf lowlands to the east and to the west of
+the isthmus, but on the Pacific lowlands they occur only to the east;
+this group includes _Bufo valliceps_, _Eleutherodactylus rhodopis_,
+_Phrynohyas modesta_, and _Phrynohyas spilomma_. Three species live to
+the east and to the west of the isthmus on the Pacific lowlands, but
+only to the west on the Gulf lowlands; these include _Eleutherodactylus
+rugulosus_, _Microbatrachylus pygmaeus_, and _Gastrophryne usta_.
+
+Six species that cross the isthmus live on the humid Gulf lowlands and
+on the humid lowlands of Chiapas and Guatemala, but not on the
+semi-arid Plains of Tehuantepec; these include _Bolitoglossa
+occidentalis_, _Eleutherodactylus rhodopis_, _Microbatrachylus
+pygmaeus_, _Phrynohyas modesta_, _Phrynohyas spilomma_, and _Rana
+palmipes_. Of these, _Microbatrachylus pygmaeus_ also occurs in
+scattered humid environments to the west of the isthmus on the Pacific
+lowlands.
+
+Two species are endemic to the isthmian region. _Bolitoglossa
+veracrucis_ is known only from the humid northern slopes of the
+isthmus. _Hylella sumichrasti_ occurs on the Pacific slopes of the
+isthmus and extends to the east into western Chiapas.
+
+In analyzing the distribution of the amphibians with respect to those
+that are restricted to either the Pacific or Gulf lowlands or those
+that cross the continental divide in the isthmus, we find that 25 per
+cent of the species are restricted to the Gulf lowlands, 17 per cent
+are restricted to the Pacific lowlands, and 53 per cent cross the
+isthmus. In analyzing the distribution patterns with respect to those
+that extend across the isthmus of Tehuantepec from east to west, we
+find that 14 per cent of the species do not extend east of the isthmus
+into Central America and that 19 per cent do not range west of the
+isthmus into Mexico proper; 61 per cent of the species range to the
+east and to the west of the isthmus. Of the 36 species of amphibians
+inhabiting the isthmus only nine species (25 per cent) range across the
+isthmus, that is, occur on the Gulf and Pacific lowlands, and also
+range to the east and to the west of the isthmus. To these wide-ranging
+species the diversified environments of the isthmus do not present a
+barrier to distribution. The other 27 species (75 per cent) either do
+not cross the isthmus from east to west or from north to south; thus,
+probably in one way or another the isthmus presents a barrier to their
+distribution.
+
+
+
+
+THE AMPHIBIAN FAUNA OF THE FOOTHILLS AND ADJACENT HIGHLANDS
+
+
+To amphibians inhabiting the foothills and mountains of southern Mexico
+and northern Central America, the isthmus presents a great barrier to
+dispersal. For example, salamanders of the genus _Thorius_, the
+_mexicanus_ and _augusti_ groups of the genus _Eleutherodactylus_, the
+_bistincta_ group of the genus _Hyla_, and the genus _Tomodactylus_
+occur on the Mexican Plateau and southward into the mountains of
+Oaxaca. Nevertheless, no members of these groups are present in the
+Guatemalan-Chiapan Highlands. The genera _Chiropterotriton_,
+_Magnadigita_, _Pseudoeurycea_, and _Ptychohyla_, as well as the
+_eximia_ group of _Hyla_ are represented by different species in the
+Guatemalan-Chiapan Highlands than in the mountains of Mexico on the
+other side of the isthmus. Several species of _Plectrohyla_ occur in
+the Guatemalan-Chiapan Highlands, but none is known from the Mexican
+Highlands, although one species occurs in the Tuxtlas.
+
+Living in the humid forests of the foothills are salamanders of the
+genus _Lineatriton_, frogs of the _spatulatus_ group of
+_Eleutherodactylus_, _Anotheca coronata_, _Hyla miotympanum_, and
+_Phyllomedusa moreleti_. All of these occur in the foothills of the
+Sierra Madre Oriental in eastern Mexico and in Los Tuxtlas.
+_Lineatriton_, _Hyla miotympanum_, and the _spatulatus_ group of
+_Eleutherodactylus_ do not occur in the foothills of the
+Guatemalan-Chiapan Highlands; those amphibians reach the end of their
+ranges at the isthmus. _Phyllomedusa moreleti_ and _Anotheca coronata_
+are found in the northern foothills of the Guatemalan-Chiapan
+Highlands, and _Phyllomedusa moreleti_ is found in the foothills on the
+Pacific slopes of the Chiapan Highlands.
+
+Although the above analysis is not so detailed as that of the lowland
+inhabitants, it does show that all of the genera and species of
+amphibians known to inhabit the foothills and highlands adjacent to the
+isthmus, only two species of amphibians cross the isthmus from one
+highland mass to the other. Thus, it is evident that the Isthmus of
+Tehuantepec presents a great barrier to dispersal of these groups of
+amphibians.
+
+
+
+
+ESTABLISHMENT OF PRESENT PATTERNS OF DISTRIBUTION
+
+
+From the foregoing analysis of geographical and ecological distribution
+in the Isthmus of Tehuantepec we may strive for an interpretation of
+the events that led to the establishment of patterns of distribution
+displayed not only by the amphibians, but other terrestrial vertebrates
+as well. The thesis that I am proposing below is based on the premise
+that in southern Mexico and northern Central America climatic
+fluctuation during the Pleistocene was of sufficient magnitude to cause
+vegetational shifts, both vertically and latitudinally, resulting in
+the establishment of alternating continuous and discontinuous lowland
+and highland environments, although this climatic fluctuation was not
+so great as to eliminate tropical lowland environments from the region.
+I feel that the present patterns of distribution of the amphibians in
+the Isthmus of Tehuantepec may be explained on this premise.
+
+Many authors dealing with the herpetofauna of Middle America have
+followed Schuchert's (1935) suggestion of a seaway in the isthmus
+during the Cenozoic. Thus, Burt (1931), Duellman (1956, 1958a), Gloyd
+(1940), Oliver (1948), Smith and Laufe (1946), and Stuart (1941)
+employed the presence of a seaway to explain distribution and
+speciation in various genera. Durham, Arellano, and Peck (1952), Olson
+and McGrew (1941), and Stirton (1954) have provided geological evidence
+that there probably was no Cenozoic seaway in the Isthmus of
+Tehuantepec. Even if there were a seaway in the Pliocene or Miocene
+(the dating of this possible seaway is open to question), its presence
+is not necessary to explain the present patterns of distribution in the
+isthmus.
+
+In recent years the study of natural biotic environments, palynology,
+and Pleistocene chronology in Middle America has produced a wealth of
+data, which although still fragmentary begins to form a picture of past
+climatic events in that part of the world. Sedimentary studies by
+Hutchinson, Patrick, and Deevey (1956) and Sears, Foreman, and Clisby
+(1955) have provided evidence of drastic climatic shifts in Mexico
+during the Pleistocene. Further evidence of bioclimatic fluctuation is
+provided by Martin and Harrell (1957) and Martin (1958); the latter has
+suggested that there was a displacement of the tropical zones in
+southern Mexico and northern Central America by as much as 3000 feet
+during the glacial maximum. Much of the evidence of such drastic
+vertical shifts in environments is based on the presence of
+Pleistocene montane glaciers on Mexican volcanoes (White, 1956) and
+Chirripo in Costa Rica (Weyl, 1955). Dorf (1959) supports this idea of
+drastic climatic change.
+
+In his studies of the avifauna of Mexico and Guatemala Griscom (1932
+and 1950) made an important issue of the continuity of the bird fauna
+in what he called the Subtropical Life-zone, which essentially consists
+of cloud forest, a widespread, but discontinuous, habitat on the Gulf
+(windward) slopes of the Mexican and Central American highlands at
+elevations between 1000 and 2000 meters. To account for this apparent
+uniformity in the avifauna Griscom hypothesized a continuity of cloud
+forest environment in the Pleistocene; this would result in the
+depression of cloud forests to the coastal lowlands and the
+displacement of tropical lowland environments far to the south in
+Central America. Stuart (1951) objected to this displacement of lowland
+tropical rainforest; he stated that a descent to sea level of a
+subtropical zone would have brought about either widespread
+extermination of the tropical fauna or acclimatization of that fauna to
+subtropical conditions.
+
+Although palynological studies and some faunal studies of subtropical
+and temperate animals suggest a drastic climatic fluctuation that might
+have eliminated tropical environments in southern Mexico and northern
+Central America, there is much biological evidence indicating the
+existence of tropical environments in this region even during the
+glacial maximum. Especially significant is the diversity of species
+inhabiting the present tropical environments; many of these have
+differentiated from related taxa to the south.
+
+In the Pleistocene, climate fluctuated and vegetation shifted
+correspondingly in southern Mexico and northern Central America. Most
+of the palynological studies and many studies of Pleistocene chronology
+deal with montane regions, either the Mexican Plateau or the mountains
+rising from the plateau. No such studies have been made in lowland
+tropical environments. During glacial advances the tropical lowland
+environments in Mexico probably were not eliminated, for the great
+diversity of animals in these environments supports the hypothesis that
+they have been in existence for some time, although periodically they
+may have been discontinuous.
+
+In order to understand the nature of bioclimatological events in the
+Pleistocene in lowland tropical environments of southern Mexico,
+certain factors that are of little importance in the interpretation of
+Pleistocene chronology in the highlands must be considered. These
+factors are: 1) climatic moderation by oceans, 2) fluctuation in sea
+level, and 3) fluctuation in level of the water table as affected by
+sea level.
+
+It is well-known that large bodies of water moderate the temperature on
+adjacent land. Furthermore, it is known that faunas of marine
+invertebrates shifted latitudinally in the Pleistocene; Trask, Phleger,
+and Stetson (1947) recorded cold-water Foraminifera then as far south
+as the Sigsbee Deep in the middle of the Gulf of Mexico. Large bodies
+of warm water, such as the Gulf of Mexico, Caribbean Sea, and Pacific
+Ocean of today, probably were not sufficiently cooled at the time of
+glacial advance to affect greatly the temperature of the winds blowing
+across them. Even if these bodies of water were somewhat cooler than
+now, the prevailing winds blowing from them onto the lowlands of Mexico
+and northern Central America would have aided in maintaining relatively
+high temperatures there. These warm winds probably counteracted the
+cooling effect of glaciation in the lowlands and thereby maintained
+tropical conditions near the seas.
+
+Although no adequate studies of Pleistocene beach lines have been made
+in southern Mexico, such information is available for peninsular
+Florida on the other side of the Gulf of Mexico (Cooke, 1945).
+Fluctuation in sea level in the Pleistocene has been used by Hubbell
+(1954), Goin (1958), and Duellman and Schwartz (1958) to explain
+present patterns of distribution of animals in Florida. If Cooke's
+interpretations can be applied to the western side of the Gulf of
+Mexico, even generally, it would be supposed that sea level varied from
+about 300 feet lower than at present during the Illinoian Glacial
+Period to about 275 feet higher than at present during the Aftonian
+Interglacial Period. Lowering of sea level would expand the lowlands in
+the isthmus; rising sea level would restrict them, leaving only the
+central ridges and many islands in the isthmus, but never forming a
+seaway between the Gulf of Mexico and the Pacific Ocean.
+
+Probably the level of the water table in the coastal lowlands and the
+gradients of the streams in the lowlands and foothills was closely
+correlated with fluctuation in sea level. If sea level fluctuated as
+much as 575 feet in the Pleistocene, changes in the level of the water
+table must have been of considerable magnitude.
+
+During times of glacial advances the lowlands of the isthmus probably
+were more extensive and had more semi-arid tropical environments than
+at present, with patches of rainforest existing in sheltered valleys
+along the major streams. In the course of bio-climatic fluctuation the
+semi-arid environments (scrub forest and/or savanna) were continuous at
+times from the Pacific lowlands across the isthmus to the Gulf
+lowlands. At those times such typical inhabitants of the semi-arid
+environments as _Rhinophrynus dorsalis_, _Engystomops pustulosus_, and
+_Hyla staufferi_ could have made their way across the isthmus. At times
+of most extensive glaciation, such as the Illinoian, temperatures in
+the isthmus probably were low enough to permit the growth of pine-oak
+forest and cloud forest continuously across the central ridges from the
+Mexican to the Chiapan-Guatemalan highlands. At those times such
+highland members of the fauna as _Chiropterotriton_, _Pseudoeurycea_,
+_Magnadigita_, and the _eximia_ group of _Hyla_ could have crossed the
+isthmus. During Wisconsin time, climate probably fluctuated less than
+during previous glaciations; probably no montane environments, except
+cloud forest, were represented in the isthmus during the Wisconsin.
+Even at this relatively late date such animals as _Lineatriton
+lineola_, _Anotheca coronata_, and _Phyllomedusa moreleti_ could have
+crossed the isthmus.
+
+During the interglacial periods, which in the isthmian region were
+characterized by warmer temperatures, higher sea level and consequently
+more restricted areas of lowlands, and possibly more rainfall than in
+the glacial periods, the continuity of pine-oak forest and cloud forest
+from east to west across the isthmus was interrupted. Probably, too,
+the semi-arid environments were restricted, and the rainforests were
+more widespread. At those times animals now inhabiting the rainforests
+of the Gulf lowlands and those inhabiting the Pacific lowlands of
+Chiapas and Guatemala could have crossed the isthmus. In this group are
+species such as _Bolitoglossa occidentalis_, _Eleutherodactylus
+rhodopis_, _Microbatrachylus pygmaeus_, and _Rana palmipes_.
+
+The amount of differentiation in isolated populations of amphibians in
+southern Mexico and northern Central America gives some idea of
+relative lengths of time of isolation from related populations. Those
+populations inhabiting high mountain environments on either side of the
+isthmus are specifically distinct. Some populations inhabiting cloud
+forests lower on the mountains are specifically distinct from related
+populations on the other side of the isthmus; between others there is
+no recognizable differentiation. Even though many populations are
+isolated from other populations of the same species in the lowlands of
+the isthmus, there is no apparent speciation. This indicates that the
+lowland environments and their inhabitants have been isolated from one
+another for a shorter time than have the highland environments and
+their inhabitants.
+
+
+
+
+ACCOUNTS OF SPECIES
+
+
+For each species of amphibian known to occur in the lowlands of the
+Isthmus of Tehuantepec, localities where one or more specimens were
+collected are listed, and variation, ecology, and life histories are
+discussed. A total of 2833 specimens has been examined for the purposes
+of this study. Individual specimens cited in the text are listed with
+catalogue numbers and abbreviations of the name of the museum, as
+follows:
+
+     AMNH  American Museum of Natural History
+     KU    University of Kansas Museum of Natural History
+     MCZ   Museum of Comparative Zoology, Harvard College
+     UIMNH University of Illinois Museum of Natural History
+     UMMZ  University of Michigan Museum of Zoology
+     USNM  United States National Museum
+
+
+=Gymnopis mexicanus mexicanus= Dumeril and Bibron
+
+     _Oaxaca_: El Barrio (3); Matias Romero; Tehuantepec (2).
+     _Veracruz_: Cosamaloapan; Cuatotolapam (2).
+
+The two specimens from Cuatotolapam were collected by Ruthven in an
+area of mixed savanna and forest. The three specimens (USNM 30535-7)
+listed above from El Barrio were collected by Sumichrast; possibly they
+came from another locality. The city of Tehuantepec is divided into
+seven districts called "barrios." The two specimens listed from
+Tehuantepec (MCZ 1604) merely bear the data "Tehuantepec, Mexico." They
+may have come from the town, the district, or from anywhere in the
+isthmus. The specimen from Matias Romero has 109 primary and 67
+secondary annuli, a length of 400 mm., and a diameter of 19 mm.; the
+one from Cosamaloapan has 106 primary and 58 secondary annuli, a length
+of 397 mm., and a diameter of 19 mm. Data on the other specimens were
+recorded by Dunn (1942:475).
+
+
+=Bolitoglossa occidentalis= Taylor
+
+     _Oaxaca_: Rio Sarabia (2); Ubero. _Veracruz_: La Oaxaquena;
+     14 km. E of Suchil.
+
+The specimens from Oaxaca are only tentatively assigned to
+_occidentalis_. All are immature and lack maxillary teeth. Taylor
+(1941:147) stated that the maxillary teeth are absent in young
+_occidentalis_. One from Rio Sarabia is a male with a body-length of 29
+mm. and a tail-length of 22 mm. The dorsum is reddish brown streaked
+with dark gray; the venter is dark gray. Two small individuals (one
+from Sarabia and one from Ubero) have body-lengths of 19 and 21 mm. and
+tail-lengths of 10.5 and 11 mm. In life they were pale yellowish tan
+above with a brown triangular mark on the occiput, but with no
+middorsal stripe. Both were found in the axils of elephant ear plants
+(_Xanthosoma_).
+
+This species has been noted by Goodnight and Goodnight (1956:146) on
+the Atlantic lowlands at Palenque, Chiapas, and by Shannon and Werler
+(1955:362) at several localities in Los Tuxtlas, Veracruz. I have
+collected it at Vista Hermosa on the eastern slopes of the Sierra Madre
+Oriental above Tuxtepec in northern Oaxaca. Both _B. occidentalis_ and
+_B. rufescens_ have been reported from Palenque, Chiapas (Taylor and
+Smith, 1945:547). Reexamination of specimens from northern Chiapas and
+Tabasco is needed to verify the sympatric occurrence of these two
+similar species.
+
+
+=Bolitoglossa platydactyla= Tschudi
+
+     _Oaxaca_: La Oaxaquena; Tolosita (2). _Veracruz_: Acayucan;
+     Cuatotolapam; 25 km. ESE of Jesus Carranza; 14 km. E of
+     Suchil; 2.7 km. N of Tula.
+
+Known only from the Gulf lowlands in the isthmian region, this species
+has been taken in a variety of habitats within the humid forest area:
+under outer leaves of banana plants, under a rock along a stream, under
+a log in a plowed field, and on a reed in a pond at night. Three adult
+males have an average snout-vent length of 44 mm. and a tail-length of
+41 mm. In life the color of the dorsum varied from orange-yellow to
+orange-tan, usually being more orange on the tail. The iris was a
+reddish orange.
+
+
+=Bolitoglossa veracrucis= Taylor
+
+     _Veracruz_: 35 km. SE of Jesus Carranza (21).
+
+This species is known only from the type series collected at night on a
+limestone cliff by Walter W. Dalquest. If this salamander is restricted
+to this type of habitat, it should be found in the region of extensive
+limestone outcroppings in northern Chiapas and southern Tabasco.
+
+
+=Rhinophrynus dorsalis= Dumeril and Bibron
+
+     _Oaxaca_: Ixtepec; Limon; Salina Cruz (18); Tehuantepec
+     (57); Tuxtepec (3). _Veracruz_: Amatitlan (3); Cosamaloapan
+     (5); Novillero (2); San Lorenzo.
+
+This species inhabits the scrub forests of the Pacific coastal plain
+and the savannas in southern Veracruz; apparently it does not occur in
+rainforest. Consequently, its distribution in the isthmus is
+discontinuous.
+
+PLATE 1
+
+[Illustration: FIG. 1. Savanna about 75 kilometers east of
+Coatzacoalcos, Veracruz. Photograph by L. C. Stuart.]
+
+[Illustration: FIG. 2. Low scrub forest near Alvarado, Veracruz.
+Photograph by L. C. Stuart.]
+
+PLATE 2
+
+[Illustration: FIG. 1. Rainforest near Tolosita, Oaxaca. March, 1956.]
+
+[Illustration: FIG. 2. Rainforest along the Rio Sarabia, Oaxaca. March,
+1956.]
+
+PLATE 3
+
+[Illustration: FIG. 1. Transition forest near La Princesa, Oaxaca.
+March, 1956.]
+
+[Illustration: FIG. 2. Palm Savanna on the Plains of Chivela, Oaxaca.
+March, 1956.]
+
+PLATE 4
+
+[Illustration: FIG. 1. Scrub forest on the Plains of Tehuantepec in dry
+season. March, 1956.]
+
+[Illustration: FIG. 2. Scrub forest on the Plains of Tehuantepec in
+rainy season. View toward the north. In the distance is the Continental
+Divide in the hills of the Isthmus. July, 1958.]
+
+PLATE 5
+
+[Illustration: FIG. 1. Low, dense scrub forest near La Ventosa, Oaxaca.
+July, 1958.]
+
+[Illustration: FIG. 2. Temporary pond in scrub forest north of Salina
+Cruz, Oaxaca. July 7, 1958. _Rhinophrynus dorsalis_, _Bufo marmoreus_,
+and _Diaglena reticulata_ were breeding here the previous night.]
+
+PLATE 6
+
+[Illustration: FIG. 1. Calling male of _Rhinophrynus dorsalis_,
+photographed in a pond north of Santa Cruz, Oaxaca, on July 6, 1958.
+x 2/3.]
+
+[Illustration: FIG. 2. Color pattern variation in two adults of _Bufo
+canaliferus_ from Juchitan, Oaxaca. x 2/3.]
+
+PLATE 7
+
+[Illustration: FIG. 1. Calling male of _Engystomops pustulosus_,
+photographed in a pond west of Tehuantepec, Oaxaca, on July 5, 1956.
+x 2.]
+
+[Illustration: FIG. 2. Foamy egg mass of _Engystomops pustulosus_ at
+the edge of a pond west of Tehuantepec, Oaxaca. July 5, 1956. x 3/8.]
+
+PLATE 8
+
+[Illustration: FIG. 1. Calling male of _Diaglena reticulata_,
+photographed at a pond north of Salina Cruz, Oaxaca, on July 6, 1958.
+x 1/2.]
+
+[Illustration: FIG. 2. Clasping pair of _Diaglena reticulata_ at the
+edge of a pond north of Salina Cruz, Oaxaca, on July 6, 1958. x 1.]
+
+Breeding congregations were found after heavy rains at Tehuantepec on
+July 5, 1956, at Cosamaloapan, Novillero, and Amatitlan on July 26,
+1956, and at Salina Cruz on July 6, 1958. The call is a long "worrp"
+made while the male is floating on the surface of the pond. The small
+heads, small limbs, and greatly inflated bodies cause the calling males
+to resemble miniature caricature balloons (Pl. 6, fig. 1). Amplexus is
+inguinal. These toads are notably wary, even when calling. Often the
+beam of a flashlight or the slightest disturbance of the water will
+cause the males to stop calling. The body is deflated with one last
+nauseous note, and the frog sinks beneath the surface of the water and
+swims away with short slow kicks of the hind feet.
+
+
+=Bufo canaliferus= Cope
+
+     _Oaxaca_: Chivela; Salina Cruz; Santa Efigenia; Tapanatepec
+     (6); Tehuantepec (10); Zanatepec (4).
+
+This small toad apparently is restricted to the Pacific lowlands from
+the Isthmus of Tehuantepec eastward to Guatemala. At Zanatepec on July
+13, 1956, males were calling from a flooded field bordered by scrub
+forest. The call is a rather loud nasal racket. Living individuals vary
+greatly in coloration. Some have yellowish tan flanks and dorsum and an
+orange middorsal stripe; others have a pale red dorsum, yellow flanks,
+and a cream middorsal stripe (Pl. 6, fig. 2).
+
+
+=Bufo coccifer= Cope
+
+     _Oaxaca_: Juchitan (5); Tehuantepec.
+
+It is with some degree of hesitancy that these toads are referred to
+the species _coccifer_. Although these and other specimens from
+Guerrero and Michoacan display no striking differences from specimens
+from Costa Rica, Nicaragua, and southeastern Guatemala, the ranges of
+the populations are separated by a broad hiatus in Chiapas and
+Guatemala. Possibly this species has utilized the sub-humid corridor
+through northern Central America (Stuart, 1954) and subsequently
+disappeared from the corridor in Guatemala and Chiapas. Specimens of a
+_coccifer_-like toad collected by Stuart in the vicinity of
+Jacaltenango, Departamento Huehuetenango, Guatemala, are much larger
+than either the Central American or Mexican specimens of _coccifer_. A
+final commitment on the systematic status must await a thorough study
+of this group of toads.
+
+Males of this species were calling from a grassy rain-pool in open
+scrub forest at the edge of Juchitan on July 6, 1956. The call is a
+low "whirrr." The calling males were sitting in the shallow water at
+the edge of pond, where they were hidden by the grass. None was
+observed in open water, as is characteristic of calling males of _Bufo
+canaliferus_ and _marmoreus_.
+
+
+=Bufo marinus= Linnaeus
+
+     _Oaxaca_: Agua Caliente; Guichicovi (3); Mixtequilla;
+     Tolosita (6); Tehuantepec (37); Tuxtepec; Union Hidalgo.
+     _Veracruz_: Ciudad Aleman (4); Cosamaloapan; Cuatotolapam
+     (19); 20 km. SE of Jesus Carranza (4); 38 km. SE of Jesus
+     Carranza (10); 20 km. NE of Jesus Carranza (4); Novillero.
+
+This large toad is abundant throughout the lowlands of the isthmus. The
+loud rattling call of males was heard on rainy nights throughout the
+summer. In March, 1956, several adults were found in a small cave back
+of a spring at Agua Caliente.
+
+
+=Bufo marmoreus= Wiegmann
+
+     _Oaxaca_: Cerro San Pedro (2); Chivela (5); Escurano (3);
+     Juchitan; Salina Cruz (101); Santa Lucia (2); 12 km. S of
+     Santiago Chivela (11); Santo Domingo; Tapanatepec;
+     Tehuantepec (100); Tequisistlan. _Veracruz_: Alvarado;
+     Coatzacoalcos.
+
+This toad is abundant on the Pacific lowlands, where it inhabits both
+open and dense scrub forest. On the Gulf lowlands its distribution
+seems to be limited to xeric coastal habitats. Aside from the specimens
+from Alvarado and Coatzacoalcos, it is known in Veracruz only from Boca
+del Rio (Langebartel and Smith, 1959:27).
+
+The similarity in size of _Bufo marmoreus_ and _valliceps_ and their
+almost completely allopatric ranges suggest that the two species may be
+in competition at any one locality. Nevertheless, both were calling
+from a small rocky stream south of Santiago Chivela on July 6, 1956.
+
+On the night of July 6, 1958, an estimated 400 toads of this species
+made up a breeding congregation near Salina Cruz. The site was a
+shallow muddy pond about 20 x 40 meters located in an area cleared of
+scrub forest; the banks of the pond were devoid of vegetation (Pl. 5,
+fig. 2). Breeding in the same pond were _Rhinophrynus dorsalis_ and
+_Diaglena reticulata_. The following morning no more than a dozen
+_Bufo_ were found in the pond, but several individuals were found
+beneath debris and in small burrows near the pond. On July 7, 1958,
+large numbers of tadpoles and recently metamorphosed young were in a
+shallow grassy pool just east of Salina Cruz.
+
+Taylor (1943b:347) referred certain specimens from Tehuantepec to _Bufo
+perplexus_, a species closely related to _Bufo marmoreus_. Evidence to
+be presented elsewhere shows that _perplexus_ does not occur in the
+isthmus.
+
+
+=Bufo valliceps valliceps= Wiegmann
+
+     _Oaxaca_: Guichicovi (2); Matias Romero; 32 km. N of Matias
+     Romero (2); Nueva Raza; Rio Sarabia (3); Santa Maria
+     Chimalapa (14); Santiago Chivela; 12 km. S of Santiago
+     Chivela (5); Santo Domingo (5); Tolosita (7). _Veracruz_:
+     Acayucan (3); Alvarado; Amatitlan; Ayentes; Cosamaloapan
+     (3); Cosoleacaque (6); Cuatotolapam (14); Hueyapan; 20 km.
+     ENE of Jesus Carranza (6); 20 km. S of Jesus Carranza; 25
+     km. SE of Jesus Carranza (23); 35 km. SE of Jesus Carranza;
+     60 km. SW of Jesus Carranza (5); La Oaxaquena (4); Novillero
+     (4); San Lorenzo (5).
+
+Individuals were found in both wet and dry seasons. In the dry season
+they were most frequently found in rainforest, whereas in the rainy
+season breeding congregations were found in savannas as well. This toad
+occurs throughout the Gulf lowlands and on the Pacific slopes and in
+the Grijalva Valley of Chiapas and Guatemala, but not on the Pacific
+lowlands of the isthmus.
+
+I have not been able to recognize individuals referrable to the race
+_macrocristatus_. Firschein and Smith (1957:219) described
+_macrocristatus_ from the mountains of eastern Oaxaca and referred to
+it specimens from the Gulf lowlands of northern Chiapas. None of the
+present material shows the hypertrophied cranial crests supposedly
+characteristic of _macroaristatus_, nor do specimens from the isthmus
+resemble the population in the Grijalva Valley being described by L. C.
+Stuart, who will discuss the variation in, and the validity of, the
+named populations of _valliceps_.
+
+Five specimens from San Lorenzo, Veracruz (USNM 123516-20), were
+identified as _Bufo cristatus_ by Smith (1947:408). Firschein (1950:83)
+redefined the _cristatus_ group of _Bufo_ and assigned these specimens
+to _valliceps_.
+
+
+=Eleutherodactylus alfredi= Boulenger
+
+     _Oaxaca_: Tolosita (2). _Veracruz_: 35 km. SE of Jesus
+     Carranza (6).
+
+These specimens were collected in rainforest. Shreve (1957:247) pointed
+out the close resemblance between _E. alfredi_ and _E. conspicuus_ from
+Piedras Negras, Guatemala, and treated them as subspecies. Examination
+of the specimens from the isthmus, together with seven from central
+Veracruz and one from Teapa, Tabasco, suggests an even closer
+relationship. _Eleutherodactylus conspicuus_ was diagnosed by Taylor
+and Smith (1945:567) as differing from _alfredi_ "in lacking a tarsal
+fold, in having shorter hind legs with the tibiotarsal articulation
+reaching only to the nostril instead of beyond the tip of the snout;
+the vomerine teeth barely reach the posterior level of the choanae."
+The specimen from Teapa has the vomerine teeth reaching to the
+posterior edge of the choanae; in the eight specimens from the isthmus
+the teeth reach the posterior edge of the choanae in two and to the
+middle of the choanae in six; in seven specimens from central Veracruz
+the teeth reach the posterior edge of the choanae in two and to the
+middle in five. The tibiotarsal articulation extends beyond the tip of
+the snout in the specimen from Teapa and in two from central Veracruz;
+in three specimens from the isthmus and in one from central Veracruz it
+extends only to the nostril; in the others it extends to the snout. The
+tarsal fold is absent in the specimen from Teapa, in three from the
+isthmus, and in all those from central Veracruz; it is weakly present
+in the others.
+
+In the light of this evidence there seems to be little justification in
+recognizing two species or even two subspecies in this group.
+Consequently, _Eleutherodactylus conspicuus_ Taylor and Smith (1945) is
+here placed in the synonymy of _Eleutherodactylus alfredi_ Boulenger
+(1898), a species with a range extending from Cuautlapan and Potrero
+Viejo in central Veracruz southward and eastward in forested habitats
+to western El Peten, Guatemala.
+
+
+=Eleutherodactylus natator= Taylor
+
+     _Veracruz_: 35 km. SE of Jesus Carranza (3); 38 km. S of
+     Jesus Carranza; 55 km. SE of Jesus Carranza.
+
+The snout-vent length is 42.0 mm. in a male and averages 59.5 mm. in
+three adult females. The tarsal fold is low and extends about half the
+length of the tarsus; the first and second fingers are subequal in
+length; the tibiotarsal articulation extends beyond the tip of the
+snout. The patches of vomerine teeth lie between the posterior margins
+of the choanae. The throat and belly are immaculate, and the soles of
+the feet are dark. In the isthmus this species can be distinguished
+from _Eleutherodactylus rugulosus_ by less rugose skin on the dorsum
+and absence of dark ventral mottling.
+
+The specimens reported here extend the known range of _natator_
+eastward from Camotlan, Oaxaca; northward in Veracruz the species
+inhabits foothills as far north as Huatusco.
+
+
+=Eleutherodactylus rhodopis= Cope
+
+     _Oaxaca_: 30 km. N of Matias Romero; Rio Sarabia (5);
+     Tapanatepec (87); Tolosita (6); between Zanatepec and
+     Tapanatepec. _Veracruz_: 25 km. SE of Jesus Carranza; 35 km.
+     SE of Jesus Carranza (2); 22 km. SSW of Jesus Carranza; 20
+     km. ENE of Jesus Carranza (7); Minatitlan; Tapalapan (5).
+
+For the purposes of the present study I am not recognizing
+_Eleutherodactylus beati_, _E. dorsoconcolor_, and _E. venustus_ as
+specifically, or even subspecifically distinct from the earlier named
+_E. rhodopis_. Probably these are mere color varieties of a single
+species.
+
+In the dry season frogs of this species were in humid forests, where
+they were most frequently found along small streams and in ravines. The
+species is widespread in the Gulf lowlands, but does not occur on the
+Plains of Tehuantepec. It does inhabit the Pacific slopes on the
+foothills of the Sierra Madre de Chiapas, the western part of which
+extends into eastern Oaxaca near Tapanatepec.
+
+
+=Eleutherodactylus rugulosus= Cope
+
+     _Oaxaca_: La Princesa (30); Modelo; Santa Lucia (10);
+     Tapanatepec (26); Tehuantepec (6); Tres Cruces (8).
+     _Veracruz_: Tapalapan (5).
+
+In addition to the specimens from the lowlands of the isthmus, for the
+purposes of the following discussion, I have included data on two
+specimens from the southern slopes of the Sierra del Sur in Oaxaca
+(Mirador and Chacalapa) and on several specimens from Los Tuxtlas in
+Veracruz (Los Chaneques, 67; Salto de Eyipantla, 35; and San Andres
+Tuxtla, 11).
+
+Frogs of the _Eleutherodactylus rugulosus_ complex occur from southern
+Veracruz and Sinaloa southward through Central America. Taylor
+(1940:401) described _E. vocalis_ from Hacienda El Sabino, Michoacan;
+Taylor and Smith (1945:580) described _E. avocalis_ from Tres Cruces,
+Oaxaca. These have been considered as species distinct from
+_rugulosus_, which is known to occur in Veracruz, Guerrero, and Chiapas
+southward into Central America. Although the large number of specimens
+collected in the isthmus does not aid in defining the ranges of the
+taxa involved, these specimens do give some idea of the variation in
+certain characters in a given population.
+
+In specimens from Los Tuxtlas the tarsal fold is well-developed and
+extends two-thirds to three-fourths the length of the tarsus; the
+tibiotarsal articulation reaches the nostril and sometimes slightly
+beyond the tip of the snout. In males the tympanum is nearly equal to
+the diameter of the eye; in females it is about one-half the diameter
+of the eye. The posterior surfaces of the thighs are dark brown or
+black with whitish or cream-colored spots, flecks, or irregular
+mottling. The tarsal fold is dark; the throat is pale in some
+individuals, but in most is mottled with dark brown or gray flecks.
+Individuals from La Princesa near the continental divide in Oaxaca show
+the same variation in body proportions and development of the tarsal
+fold. The posterior surfaces of the thighs are dark brown indistinctly
+mottled with lighter brown. The throat is dark brown. Specimens from
+the Pacific slopes of Oaxaca, including the Plains of Tehuantepec, have
+dark brown thighs mottled with dusty cream. The tibiotarsal
+articulation extends slightly beyond the tip of the snout in all
+specimens. In males the tympanum is equal to about two-thirds the
+diameter of the eye. Duellman (1958b:6) discussed the variation in
+these characters in populations in Colima, Jalisco, and Michoacan.
+
+Until the extent of variation of these characters is known throughout
+the range of _rugulosus_, the recognition of populations either as
+species or subspecies seems superfluous. Consequently, I have used the
+oldest name; this does not necessarily imply, however, that all
+populations of _rugulosus_ (_sensu lato_) are conspecific.
+
+Of the 200 specimens examined, 15 have a middorsal stripe that is red
+or yellow. The iris varies from a copper to a dark golden color and
+shines bright red at night. Many of the specimens are juveniles; these
+were collected in the dry season, at which time they were found beneath
+rocks along streams, in road culverts where there was some water, and
+in holes in banks and cliffs.
+
+
+=Microbatrachylus pygmaeus= Taylor
+
+     _Oaxaca_: La Princesa (5); Matias Romero (9); Rio Sarabia
+     (41); Tolosita (2). _Veracruz_: Jesus Carranza; 20 km. ENE
+     of Jesus Carranza.
+
+The specimens listed above vary widely in color patterns; some of the
+patterns are characteristic of certain named "species": _albolabris_,
+_imitator_, _lineatissimus_, and _minimus_. The large series from the
+Rio Sarabia contains all of the color patterns; this series was
+obtained in one small ravine in the rainforest. At least in the
+isthmian region, this species does not inhabit the Pacific slopes and
+lowlands.
+
+
+=Syrrhophus leprus= Cope
+
+     _Oaxaca_: 33 km. N of Matias Romero; Santa Efigenia.
+     _Veracruz_: San Lorenzo.
+
+Although the type locality is stated to be Santa Efigenia on the
+Pacific slopes of the Sierra Madre de Chiapas in eastern Oaxaca, the
+type specimen probably came from the northern slopes of the mountains.
+All other known specimens are from the Gulf slopes and lowlands, and
+from several localities in Los Tuxtlas. Details concerning specimens
+from the isthmus and other parts of the range were given by Duellman
+(1958c:8).
+
+Smith (1947:408) reported a specimen of _Syrrhophus verruculatus_
+Peters from San Lorenzo, Veracruz; he stated that this specimen (USNM
+123530) could not be _S. leprus_, because it had a gray belly, nor _S.
+cystignathoides_, because of the dark and light dorsal coloration.
+Firschein (1954:57) in his review of the species of _Syrrhophus_ in
+eastern Mexico referred the specimen to _S. cystignathoides_. The
+specimen is in poor condition. Nevertheless, specific determination is
+possible. Numerous specimens of _S. leprus_ from Los Tuxtlas have gray
+bellies; some have heavier pigmentation than the specimen from San
+Lorenzo. In preservative the dorsum is dark brown with lighter
+mottling. There is little doubt that the specimen from San Lorenzo is
+a _Syrrhophus leprus_, an abundant and widespread species in the
+humid Gulf lowlands of southern Mexico, and not _verruculatus_, if
+this is a valid species (see Firschein, _op. cit._:58), and not
+_cystignathoides_, a species known from San Luis Potosi southward to
+central Veracruz.
+
+
+=Syrrhophus pipilans pipilans= Taylor
+
+     _Oaxaca_: Cerro Arenal; Cerro San Pedro; 6 km. N of Chivela;
+     14 km. W of Tehuantepec (2).
+
+In the isthmian region this frog is known only from the Pacific slopes
+and the Plains of Tehuantepec. Males call from the ground and from
+trees to heights of about four meters. The call is a single, high, long
+"peep."
+
+
+=Engystomops pustulosus= Cope
+
+     _Oaxaca_: Chivela; La Ventosa (3); Santo Domingo;
+     Tapanatepec (14); Tehuantepec (61); Union Hidalgo (62).
+     _Veracruz_: Acayucan; Cuatotolapam (7); 10 km. SE of
+     Hueyapan (11).
+
+Large congregations were breeding at Tehuantepec on July 5, at
+Tapanatepec on July 13, and at Hueyapan on July 24, 1956. The frogs
+were breeding in open ponds in scrub forest and savanna; none was found
+in the rainforest. Males call while floating on the water (Pl. 7, fig.
+1); the call is a soft "do-ing, do-ing" with a rising tone on the last
+note. Numerous individual egg masses were along the bank of a pond near
+Tehuantepec; one large composite egg mass there had a surface area of
+about one square meter (Pl. 7, fig. 2). The large series from Union
+Hidalgo was obtained by digging specimens out of a dry sandy river bank
+in the dry season. Some of the individuals were buried to a depth of 25
+centimeters.
+
+In life individuals from the Pacific lowlands were dull brown and gray;
+those from Acayucan were dark chocolate brown to black with pink or red
+blotches, forearms, and dorsal stripe. Not all specimens from the
+Atlantic lowlands are so colored; individuals from Cordoba and
+Mirador, Veracruz, are like those from Tehuantepec.
+
+
+=Leptodactylus labialis= Cope
+
+     _Oaxaca_: Agua Caliente; Chivela (2); Matias Romero (12); 33
+     km. N of Matias Romero (4); Mixtequilla; Santa Efigenia;
+     Tapanatepec; Tehuantepec (38); Tolosita (2); 33 km. W of
+     Zanatepec (49). _Veracruz_: Acayucan (3); Ciudad Aleman;
+     Cuatotolapam (10); Hueyapan; La Oaxaquena (4); 38 km. SE of
+     Jesus Carranza; 20 km. ENE of Jesus Carranza; Novillero (3);
+     San Lorenzo (2).
+
+Although _Leptodactylus labialis_ does not appear to be so abundant as
+_Leptodactylus melanonotus_, the former was found throughout the
+lowlands of the isthmus. In the dry season individuals were found along
+streams, and in the rainy season breeding congregations were found in
+rain pools, marshes, ponds, and even small puddles. The call is a slow
+"wort, wort, wort." Males call beneath the water and from beneath rocks
+and from holes in the ground. The average snout-vent length of eight
+adult males is 37.2 mm. A completely metamorphosed juvenile obtained at
+Hueyapan on July 24, 1956, has a snout-vent length of 11 mm.
+
+
+=Leptodactylus melanonotus= Hallowell
+
+     _Oaxaca_: Agua Caliente (25); Cerro Arenal (2); Cerro
+     Quiengola (3); Cerro San Pedro (3); Chivela (2); Coyol;
+     Juchitan; Matias Romero (11); Mixtequilla (2); Papaloapan
+     (2); Salazar (9); Salina Cruz; 11 km. S of Santiago Chivela;
+     Tapanatepec (17); Tehuantepec (176); Tolosita; Union
+     Hidalgo; 27 km. W of Zanatepec (6). _Veracruz_: Acayucan;
+     Cuatotolapam (9); Cosoleacaque; 20 km. ENE of Jesus Carranza
+     (2); 20 km. SE of Minatitlan (2); Novillero; San Lorenzo
+     (6).
+
+This frog is abundant throughout the lowlands of the isthmus, where in
+the dry season individuals were found along streams and beneath rocks
+at a spring seepage. In the rainy season males were calling from nearly
+every bit of standing water. The call is a soft clicking sound
+resembling that made by striking two small stones together. The average
+snout-vent length of ten adult males is 41.8 mm. There is considerable
+variation in the extent of the yellowish brown glandular areas on the
+belly. Some have none, whereas others have a broad area on the chest, a
+band along the flanks, and a thin band across the lower abdomen.
+Individuals collected in the dry season vary in the same fashion as do
+those collected in the rainy season, at which time they were breeding.
+The glands are equally well-developed in adults of both sexes, and were
+present in some juveniles with snout-vent lengths of less than 20 mm.
+Apparently the development of the glands is not associated with
+maturity, sex, or size.
+
+
+=Diaglena reticulata= Taylor
+
+     _Oaxaca_: Cerro Arenal; Chivela; Salina Cruz (26); San
+     Antonio (3); Tehuantepec (2); 8.6 km. W of Tehuantepec (11);
+     Zarzamora.
+
+Breeding congregations of this rare frog were found 8.6 kilometers west
+of Tehuantepec on July 5, 1956, and at Salina Cruz on July 6, 1958.
+Both choruses took place immediately after torrential rains. In both
+instances the frogs were in and about open muddy pools in the scrub
+forest (Pl. 5, fig. 2); males called from the bank near the water, and
+clasping pairs were found only on land (Pl. 8, figs. 1-2). The call is
+a loud, nasal "braaa," two to three seconds in duration. Amplexus is
+axillary.
+
+The dorsal ground color is light yellowish green tending towards olive
+on the head and fading to yellow on the flanks. The ventral surfaces,
+including the vocal sac, are white; the iris is golden and flecked with
+black. The present series agrees well with the description of
+_reticulata_ (based on two specimens) given by Taylor (1942:60). A
+detailed analysis of variation, comparison with related species, and
+descriptions of tadpoles are reserved for a future report.
+
+
+=Hyla baudini= Dumeril and Bibron
+
+     _Oaxaca_: Bisilana; Cerro Quiengola (2); Cerro San Pedro;
+     Coyol; Matias Romero (12); Mixtequilla; Rio Sarabia (7);
+     Salazar; San Antonio; 11 km. S of Santiago Chivela; Santo
+     Domingo (3); Tapanatepec (2); Tehuantepec (23); Tolosita.
+     _Veracruz_: Acayucan; Amatitlan; Ciudad Aleman (3);
+     Cosamaloapan (2); Cuatotolapam (15); 10 km. SE of Hueyapan;
+     20 km. S of Jesus Carranza; 38 km. S of Jesus Carranza (2);
+     20 km. ENE of Jesus Carranza (4); La Oaxaquena (2);
+     Minatitlan (2); Naranja (3); Novillero (9); Rio de las
+     Playas (2); San Lorenzo (5); Tapalapan (2).
+
+Commonly found on both sides of the isthmus, this large tree frog
+nearly always is associated with trees; it is not found in the
+savannas, although it breeds in savannas adjacent to rainforest. It
+appears to be somewhat more abundant in scrub forest than in
+rainforest. In the daytime individuals were found under the outer
+sheaths of banana plants, in the axils of leaves of elephant ears
+(_Xanthosoma_), in cavities in trees, and on shaded limbs in the
+forest. Recently metamorphosed individuals having snout-vent lengths
+slightly more than 20 mm. were found in the latter part of July.
+
+
+=Hyla ebraccata= Cope
+
+     _Oaxaca_: Donaji (17); 43 km. N of Matias Romero (27);
+     Sarabia (6); Tolosita (3); Ubero (17). _Veracruz_: Aquilera.
+
+This small species was found only in forested areas, where calling
+males were on bushes and trees around rain pools. The call is a harsh
+squawk repeated at intervals of 15 to 20 seconds, followed by a minute
+or more of silence, and then repeated. Clasping pairs were found on
+bushes and in the water.
+
+The dorsum bears a dark chocolate brown hour glass-shaped mark, which
+in some individuals is broken into a large mark posteriorly and a
+smaller triangular one on the head and nape. The dorsal ground color
+varies from pale cream or ivory to yellow or tan. The intensity of the
+dorsal pigmentation is subject to rather rapid change. The flanks,
+hands, and anterior part of the venter are lemon yellow; the feet,
+thighs, and posterior part of the venter are golden yellow. The dorsal
+surface of the shank is yellow to tan with chocolate brown bars or
+spots; the heel is pale yellow. There is a dark brown bar in the loreal
+region and a dark brown bar extending posteriorly from the eye to a
+point above the insertion of the forelimb. The iris is a copper color.
+The toes are completely webbed; the fingers, one-third webbed. There is
+a small axillary web that is evident when the forelimbs are at right
+angles to the body. Twenty males have an average snout-vent length of
+28.1 mm.; three females, 35.3 mm. There are no nuptial tuberosities on
+the pollex of breeding males.
+
+This species has been collected at Coyame and Catemaco in Los Tuxtlas
+and at various localities in Tabasco; it apparently ranges eastward
+from southern Veracruz, Mexico, in humid forests to El Peten,
+Guatemala.
+
+
+=Hyla loquax= Gaige and Stuart
+
+     _Oaxaca_: Donaji (7); 43 km. N of Matias Romero (21).
+     _Veracruz_: 19 km. N of Acayucan (4); Aquilera (3); 8 km. SW
+     of Coatzacoalcos (36); Cuototolapam (11); Naranja (13); San
+     Lorenzo (8).
+
+In the isthmus this species is known only from the humid forests of the
+Gulf lowlands; it is also known from Boca del Rio, Veracruz, and from
+Teapa and Villa Hermosa, Tabasco.
+
+Calling males were found on aquatic plants above the water in deep
+ponds in the forest where it was necessary for the collector to wade
+waist-deep in water to obtain them. The call is a loud "hah-onk."
+Individuals, when active at night, are yellowish tan above with light
+olive green spots. The flanks, belly, and vocal sac are yellow, and the
+anterior and posterior surfaces of the thighs and webbing of the feet
+are bright orange-red or tomato red. Individuals found during the day
+are grayish brown with olive markings or reddish brown with black
+markings. Sleeping individuals are ivory-gray with faint gray markings.
+The iris is a bright copper color. Fifteen adult males have an average
+snout-vent length of 41.7 mm.; they have no horny nuptial pads on the
+pollex.
+
+The relationships of this species are with _Hyla rickardsi_ Taylor, a
+species known only from the foothills of the Sierra Madre Oriental in
+the states of Puebla and Veracruz. The distinguishing characteristics
+of these species are given in Table 1. Living individuals may be
+distinguished immediately by the flash colors on the thighs--red in
+_loquax_ and yellow in _rickardsi_. The calls of the two species are
+distinctly different; that of _rickardsi_ is a high-pitched, loud
+rattle continued for several seconds, notably different from the
+goose-like honk of _loquax_.
+
+TABLE 1.--COMPARISON OF CERTAIN CHARACTERS IN HYLA LOQUAX
+AND HYLA RICKARDSI
+
+=================================+================+====================
+          CHARACTER              |   _loquax_     |    _rickardsi_
+---------------------------------+----------------+--------------------
+Toe webbing                      | Full           | Three-fourths
+                                 |                |
+Finger webbing                   | Three-fourths  | One-half
+                                 |                |
+Average snout-vent length (Male) | 41.7 mm.       | 37.4 mm.
+                                 |                |
+Tympanum/eye (Male)              | 63.2%          | 55.8%
+                                 |                |
+Dorsal leg pattern               | Barred         | Unmarked
+                                 |                |
+Tarsal fold                      | Tubercular     | Absent
+                                 |                |
+Tarsal stripe                    | Absent or      | Broad, indistinct,
+                                 |   indistinct   |   or absent
+                                 |                |
+Dorsolateral stripe              | Absent         | Present
+                                 |                |
+Light line over anus             | Broad          | Narrow
+                                 |                |
+Flash colors                     | Red            | Yellow
+                                 |                |
+Iris color                       | Copper         | Bronze
+---------------------------------+----------------+--------------------
+
+The three specimens from San Lorenzo, Veracruz (USNM 123513-5), were
+identified as _Hyla rickardsi_ by Smith (1947:409). The flash colors
+have faded in preservative, and so are of no aid in identifying these
+specimens. Two are adult females with snout-vent lengths of 35 and 39
+mm. In possessing a relatively large tympanum and barred thighs, and in
+lacking a dorsolateral stripe they are typical of _loquax_, but in the
+amount of webbing on the hands and feet, broad tarsal stripe, and
+narrow anal stripe they are like _rickardsi_. The third specimen, a
+juvenile, has a snout-vent length of 25 mm. In coloration it resembles
+the adults; it has more distinct bars on the limbs. On the basis of
+geography these specimens should be _loquax_, for the closest known
+record of _rickardsi_ is more than 200 kilometers to the northwest,
+whereas _loquax_ is known from several localities around San Lorenzo.
+
+Shannon and Werler (1955:383) described _Hyla axillamembrana_ from the
+lower southern slopes of Los Tuxtlas. The unique type is a small male
+(27 mm. snout-vent). I have examined the type and find no great
+differences between it and small specimens of _loquax_. It is not
+possible to determine the color of the thighs, nor was this information
+given in the description. _Hyla axillamembrana_ is here considered to
+be a synonym of _Hyla loquax_.
+
+
+=Hyla microcephala martini= Smith
+
+     _Oaxaca_: Donaji (15); 43 km. N of Matias Romero (19); Rio
+     Sarabia (2); Sarabia (11); Tolosita. _Veracruz_: Acayucan
+     (17); Alvarado (41); Aquilera (21); 8 km. SW of
+     Coatzacoalcos (10); Cosoleacaque (26); 10 km. SE of
+     Hueyapan; Naranja (3); Novillero.
+
+This frog is abundant in the Gulf lowlands of the isthmus, where large
+breeding congregations were found in grassy ponds on the savannas and
+in openings in the forest. Most frequently males were calling from
+grasses and reeds in the ponds; many individuals were perched
+precariously on thin blades as high as one meter above the water. The
+call is a series of low squeaks.
+
+Individuals found at night were pale yellow above with light brown
+lines arranged in an irregular pattern on the back, but often forming a
+cross or an X-shaped mark in the scapular region. There is a brown
+stripe from the nostril to the eye and thence to the groin. Anteriorly
+this stripe is bordered above by a thin white or cream-colored line.
+Numerous small brown flecks are scattered on the back and dorsal
+surface of the shank. In most specimens there are thin transverse brown
+bars on the shank. The thighs and undersides of the limbs are golden
+yellow; the belly and vocal sac are lemon yellow. The iris is yellowish
+brown. During the day individuals assume a pale reddish tan ground
+color with darker brown markings. Twenty-five adult males from Alvarado
+have an average snout-vent length of 24.1 mm.
+
+
+=Hyla picta= Guenther
+
+     _Oaxaca_: Donaji (8); Sarabia (11); Tolosita (15); Ubero
+     (6). _Veracruz_: 19 km. N of Acayucan (4); Alvarado (5);
+     Aquilera; 8 km. SW of Coatzacoalcos; 10 km. SE of Hueyapan
+     (7); Lerdo de Tejada; Tula (3).
+
+Widespread in the forests, scrub, and savannas on the Gulf lowlands of
+the isthmus, these frogs were found breeding at numerous localities.
+Males call from grasses and bushes growing in and about ponds. The
+call is a high-pitched insect-like trill. At night these frogs are pale
+yellow above; they change to light grayish tan during the day. A dark
+stripe extends from the nostril to the eye and thence posteriorly to a
+point between the axilla and groin. Above this dark stripe is a broader
+white stripe. Scattered on the dorsum are brown flecks or spots; the
+shanks are marked with poorly-defined cross-bars. The thighs are deep
+yellow below and paler above with scattered dark flecks. The belly is
+white, and the vocal sac is yellow. The iris is golden. Twenty males
+have an average snout-vent length of 21.5 mm.; three females, 24.0 mm.
+
+
+=Hyla robertmertensi= Taylor
+
+     _Oaxaca_: Tapanatepec (28); 7.5 km. NW of Tapanatepec (38);
+     7.2 km. WNW of Zanatepec (77).
+
+This species was found in the isthmian region only on the Pacific
+lowlands at the southern base of the western part of the Sierra Madre
+de Chiapas. On July 13, 1956, many large choruses were discovered. The
+calling males were on reeds and thorn scrub in and at the edge of
+temporary ponds; the call is a cricket-like "creak-creack," quickly
+followed by a series of notes "creak-eek-eek-eek-eek."
+
+At night the dorsal ground color is pale yellow; this changes to
+pinkish buff during the day. There is a grayish or brown dark stripe
+from the nostril to the eye; the stripe continues to the groin. This
+dark stripe is bordered above by a narrow white stripe. The belly is
+white, and the vocal sac is yellow. The iris is dull reddish brown.
+Twenty-five males have an average snout-vent length of 24.7 mm.
+
+
+=Hyla staufferi= Cope
+
+     _Oaxaca_: Chivela; Huilotepec (5); Juchitan (4); Matias
+     Romero (4); 25 km. N of Matias Romero; Mixtequilla (4); Rio
+     Sarabia (11); 11 km. S of Santiago Chivela; Sarabia (3);
+     Tapanatepec (67); Tehuantepec (66); Tolosita (2); Ubero;
+     Union Hidalgo; Zanatepec (6). _Veracruz_: Acayucan (7);
+     Alvarado (3); Amatitlan; Aquilera; Ciudad Aleman (3); 8 km.
+     SW of Coatzacoalcos (9); Cosamaloapan (4); Cosoleacaque (8);
+     10 km. SE of Hueyapan; Lerdo de Tejada; Novillero (6); Tula
+     (2).
+
+This is the only species of small hylid that crosses the isthmus.
+Calling males were found in and about ponds on the savannas in southern
+Veracruz, in ponds in open forest in northern Oaxaca (not in forest
+pools), and in temporary pools in the scrub forest on the Pacific
+lowlands. Individuals usually called from bushes and reeds in or at the
+edge of ponds. The call is a short "braaa." Dates of breeding choruses
+indicate that by the time the other small species of hylids in the Gulf
+lowlands reach the peak of their breeding season, that of _H.
+staufferi_ is essentially over; no large breeding congregations were
+found in July. On July 8, 1956, two metamorphosing young were found
+clinging to blades of grass in a pond; they had snout-vent lengths of 8
+and 9 mm. and tail stumps less than 3 mm. in length. Others were found
+on July 13 and 26. The juveniles are nearly unicolor olive green above
+and white below.
+
+In life the adults vary greatly in color pattern. The dorsal ground
+color is yellowish tan to olive brown with olive brown or dark brown
+spots, some of which in certain individuals are connected to form
+longitudinal dark stripes. On the posterior surface of the thighs are
+small white flecks. The belly is white, and the vocal sac is a rich
+yellow. Twenty males have an average snout-vent length of 26.3 mm.;
+they have no horny nuptial pads. No noticeable differences in either
+color or body proportions were found between the populations on either
+side of the isthmus.
+
+
+=Hylella sumichrasti= Brocchi
+
+     _Oaxaca_: Cerro Arenal (5); Cerro San Pedro (2); Escurano;
+     La Concepcion (41); Portillo Los Nanches (6); San Antonio
+     (16); 11 km. S of Santiago Chivela (18); Santa Lucia (7);
+     Tapanatepec (5); Tehuantepec (8); Tenango (49); Tres Cruces
+     (19).
+
+With the exception of the series from 11 kilometers south of Santiago
+Chivela, most of these specimens were found in small arboreal
+bromeliads during the dry season. Males were found along a clear,
+shallow, rocky stream south of Santiago Chivela on July 6, 1956. The
+frogs were calling from bushes and rocks in and along the stream. When
+disturbed, they jumped into the water and floated downstream until they
+were able to hold onto a rock or other object. The call is a loud
+"bra-a-ah." In breeding individuals the dorsum is pale yellow; the
+belly is white, and the vocal sac is yellow. The iris is pale golden
+yellow. Eighteen males have an average snout-vent length of 25.2 mm.
+All have dark brown nuptial tuberosities on the pollex.
+
+Certain diagnostic characters of this species as given by Taylor
+(1943a:50) and Taylor and Smith (1945:598) are in need of revision.
+_Hylella sumichrasti_ has been characterized as having no vocal sac,
+rarely having vomerine teeth, and as having a relatively smooth throat.
+The vocal sac in breeding males is quite evident; it is single, median,
+and when expanded, spherical. The openings into the vocal sac are
+narrow slits along the inner posterior border of the jaw rami. Of 151
+specimens studied, 74 have vomerine ridges between the choanae, and 36
+of these have one to three teeth on each ridge. The belly and
+undersurfaces of the thighs are granular; the throat is only somewhat
+less so. The granular condition may be correlated with breeding, for
+specimens obtained from bromeliads in the dry season had rather smooth
+throats. It seems that the vocal sac atrophys in the non-breeding
+season. These seasonal changes may account for the diagnoses given by
+Taylor (_op. cit._) and Taylor and Smith (_op. cit._); likewise, since
+many of the specimens obtained by Smith in the dry season were
+juveniles and subadults, the development of the vomerine ridges could
+not be diagnosed properly.
+
+The range of this species encompasses the Pacific slopes of the Isthmus
+of Tehuantepec eastward to the upper Cintalapa Valley and vicinity of
+Tonala in western Chiapas. Priscilla Starrett collected tadpoles of _H.
+sumichrasti_ from a stream 19 km. N of Arriaga, Chiapas. These limited
+observations on the ecology of this frog suggest that it breeds in the
+fast-moving streams of the Pacific slopes, and that it seeks shelter in
+arboreal bromeliads during the dry season.
+
+
+=Phrynohyas modesta= Taylor and Smith
+
+     _Oaxaca_: Tuxtepec. _Veracruz_: 20 km. S of Jesus Carranza;
+     20 km. ENE of Jesus Carranza (2); Minatitlan.
+
+I have not collected this species in the isthmus. The locality records
+indicate that the range is discontinuous (Duellman, 1956:27). The
+species occurs on the humid Pacific slopes from south-central Chiapas
+eastward to El Salvador and on the humid Gulf lowlands from southern
+Veracruz eastward into Tabasco, but is unknown from the dry Pacific
+slopes and plains in the isthmus.
+
+The acquisition of several specimens of this species in southern
+Veracruz, Tabasco, and Oaxaca, together with a knowledge of the
+variation displayed by _Phrynohyas spilomma_, suggests that _modesta_
+may be a color variety of _spilomma_.
+
+
+=Phrynohyas spilomma= Cope
+
+     _Oaxaca_: Tapanatepec (3). _Veracruz_: Amatitlan (12);
+     Chacaltianguis (2); Ciudad Aleman (6); Cosamaloapan;
+     Novillero (3).
+
+Like the preceding species, this frog is unknown from the arid Pacific
+lowlands of the isthmus; its presence at Tapanatepec, a locality
+situated in more mesic conditions than prevail on the Plains of
+Tehuantepec, indicates that it may have a distribution on the Pacific
+slopes much like that of _P. modesta_. Furthermore, this frog was not
+detected in the rainforests of the Gulf lowlands; in that region it was
+found only in scrub forest and savanna.
+
+On July 26, 1956, numerous choruses of these frogs were heard between
+Ciudad Aleman and Tlacotalpan, Veracruz. The call is a loud, nasal
+"grawl" repeated continuously. The males call from the water. Several
+clasping pairs were found in shallow grassy ponds amidst the scrub
+forest. The ground color varies from reddish brown to tan with dark
+brown dorsal markings. The iris is golden, and the vocal sacs are dark
+olive brown. After a light shower during the dry season, six
+individuals were found on the low branches of trees at night near
+Ciudad Aleman.
+
+
+=Phyllomedusa callidryas taylori= Funkhouser
+
+     _Oaxaca_: Donaji (9); Sarabia (8); Tolosita (6); Ubero (27).
+     _Veracruz_: Alvarado (7); Aquilera; Berta; Coatzacoalcos
+     (9); 10 km. SE of Hueyapan (5); Naranja (17).
+
+In life this frog presents a striking array of colors. The dorsum
+varies from pale green to dark olive green; there may be scattered
+whitish or cream-colored spots on the back. On the flanks are bright
+yellow to deep cream-colored vertical bars separated by pale blue or
+purple interspaces. The thighs and undersurfaces of the hind limbs are
+golden orange; the belly is yellow, and the throat is cream-colored.
+The iris is crimson; the transparent part of the lower eyelid has
+golden reticulations. When the frog is resting, the forefeet are folded
+beneath the throat, and the limbs are folded tightly against the body.
+In this position and with the eyes closed and head flattened, this
+gaudy frog assumes the appearance of a small elliptical green leaf.
+
+Throughout the month of July, 1956, _Phyllomedusa_ was breeding in
+ponds in or adjacent to the rainforest in northern Oaxaca and in
+southern Veracruz. Only at Alvarado was it found breeding in a grassy
+pond. Males and females alike were found on bushes and trees in and
+around the ponds. The call is a single "wank." Amplexing males continue
+to call, but the call is softer and less nasal in quality. The eggs are
+encased in pale green gelatin and attached to leaves on branches
+overhanging the water. Three egg clutches contained 38, 41, and 46
+eggs.
+
+
+=Phyllomedusa dacnicolor= Cope
+
+     _Oaxaca_: Escurano; Tehuantepec.
+
+Although it is abundant on the Pacific lowlands to the northwest in
+Guerrero, Michoacan, and Colima, this species is known only from two
+specimens from Tehuantepec. There is no apparent physical barrier to
+their distribution in the isthmus; in the Balsas Basin the species
+lives in a hotter, more arid environment than that at Tehuantepec.
+
+
+=Gastrophryne usta= Cope
+
+     _Oaxaca_: Santa Efigenia; Tehuantepec (10); 24 km. W of
+     Tehuantepec; Tolosita (2). _Veracruz_: Ayentes (6); La
+     Oaxaquena; Novillero (2); San Lorenzo.
+
+Calling males were found in open scrub forest near Tehuantepec and in
+savannas near Novillero. The specimens from Tolosita were found under
+cover in a clearing in the forest (Fugler and Webb, 1957:106).
+
+Specimens from the Pacific lowlands are typical of _Gastrophryne usta
+gadowi_ Boulenger in possessing a thin line on the posterior surface of
+the thighs and a thin line from the snout to the vent. Of nine
+specimens from the Gulf lowlands (Ayentes, Novillero, and San Lorenzo),
+seven have a middorsal line; this is narrow in four and wide in three.
+Five have the stripes on the thighs. Two specimens from the middle of
+the isthmus (Tolosita) have no stripes on the thighs; one has a thin
+middorsal line, and the other has a broad line. The adult males have a
+black throat; females have a mottled one. The brown reticulations on
+the bellies of specimens from the Gulf lowlands is bolder than on
+specimens from the Pacific lowlands. The presence of certain characters
+supposedly diagnostic of the subspecies _gadowi_ (line on dorsum and
+thighs) in the population of _usta_ in southern Veracruz suggests that
+a redefinition of the ranges of these subspecies will be in order when
+sufficient material is available to delimit them accurately. For the
+present I prefer to consider all specimens from the isthmus solely as
+_Gastrophryne usta_ without referring them to subspecies.
+
+
+=Rana palmipes= Spix
+
+     _Oaxaca_: Matias Romero (11); 11 km. S of Santiago Chivela;
+     Santo Domingo; Sarabia. _Veracruz_: Coatzacoalcos;
+     Cuatotolapam; 25 km. SE of Jesus Carranza (4); Tlacotalpan
+     (2); Tula.
+
+Adults were found along streams and in marshes in savannas and
+rainforest. These frogs are wary and difficult to capture, even at
+night. _Rana palmipes_ is another species that has a discontinuous
+distribution in the isthmus. The species does not occur on the Pacific
+lowlands of the isthmus, but does occur on the more humid Pacific
+slopes of Chiapas and Guatemala.
+
+Tadpoles were found in a small sluggish tributary to the Rio Sarabia.
+
+
+=Rana pipiens= Schreber
+
+     _Oaxaca_: Agua Caliente; Cerro Quiengola; Escurano (14); Rio
+     Sarabia (2); Tapanatepec (5); Tehuantepec (24). _Veracruz_:
+     Acayucan; Cuatotolapam (15); Jesus Carranza (2); 20 km. S of
+     Jesus Carranza (11); 25 km. SE of Jesus Carranza; 20 km. ENE
+     of Jesus Carranza (10); San Lorenzo (10).
+
+As in most other places in Mexico and northern Central America, this
+species occurs wherever there is permanent water. Males were heard
+calling from woodland ponds and from savanna ponds.
+
+
+
+
+SUMMARY
+
+
+Investigations of the amphibians and their environments in the Isthmus
+of Tehuantepec have been presented with the aim of gaining an
+understanding of the present biological and of the historical events
+responsible for the present patterns of distribution of amphibians in
+this region.
+
+The Isthmus of Tehuantepec embraces three major environments--savanna,
+semi-arid scrub forest, and quasi-rainforest. The rainforest presents
+an environment noticeably different from the other two and has a
+different amphibian fauna.
+
+Analysis of present patterns of distribution shows that certain species
+are restricted to the rainforests on the Gulf lowlands; others live
+only in the semi-arid scrub forests on the Pacific lowlands. A third
+group of species lives on both the Gulf and Pacific lowlands; most of
+these species occur only in the scrub forests or savannas on the Gulf
+lowlands, but some also inhabit the rainforest. In one way or another
+the isthmus presents a barrier to the distribution of 75 per cent of
+the species of amphibians living in the lowlands; it is a greater
+barrier still to the species inhabiting the highlands on either side.
+
+Present patterns of distribution are attributed to bioclimatic
+fluctuation in the Pleistocene. In the course of these climatic shifts,
+tropical environments and their amphibian inhabitants seem to have
+survived in the isthmian region.
+
+The amphibian fauna of the lowlands of the Isthmus of Tehuantepec
+consists of 16 genera and 36 species. Systematic studies of all
+available specimens from the region show that _Eleutherodactylus
+conspicuus_ Taylor and Smith is a synonym of _Eleutherodactylus
+alfredi_ Boulenger and that _Hyla axillamembrana_ Shannon and Werler is
+a synonym of _Hyla loquax_ Gaige and Stuart.
+
+
+
+
+LITERATURE CITED
+
+
+BEARD, J. S.
+
+     1953. The savanna vegetation of northern tropical America.
+     Ecol. Mono., vol. 23 (2):149-215.
+
+BOULENGER, G. A.
+
+     1898. Fourth report on additions to the batrachian
+     collection in the Natural History Museum. Proc. Zool. Soc.
+     London, 1898, pp. 473-482, pls. 38-39.
+
+BURT, C. E.
+
+     1931. A study of the teiid lizards of the genus
+     _Cnemidophorus_ with special reference to their phylogenetic
+     relationships. Bull. U. S. Nat. Mus., No. 154, pp. viii +
+     286.
+
+CONTRERAS A., A.
+
+     1942. Mapa de las provincias climatologias de la Republica
+     Mexicana. Mexico, D. F., Direccion de Geografia, Meterologia
+     e Hidrologia, pp. i-xxviii, tables 1-54, 2 maps.
+
+COOKE, C. W.
+
+     1945. Geology of Florida. Florida Geol. Surv., Geol. Bull.,
+     No. 29:1-339.
+
+DORF, E.
+
+     1959. Climatic changes of the past and present. Contrib.
+     Mus. Paleo. Univ. Michigan, vol. 13 (8):181-210.
+
+DUELLMAN, W. E.
+
+     1956. The frogs of the hylid genus _Phrynohyas_ Fitzinger,
+     1843. Miscl. Publ. Mus. Zool. Univ. Michigan, No. 96:1-47,
+     pls. 1-6.
+
+     1958a. A monographic study of the colubrid snake genus
+     _Leptodeira_. Bull. Amer. Mus. Nat. Hist., vol. 114:1-152,
+     pls. 1-31.
+
+     1958b. A preliminary analysis of the herpetofauna of Colima,
+     Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+     589:1-22.
+
+     1958c. A review of the frogs of the genus _Syrrhophus_ in
+     western Mexico. Occas. Papers Mus. Zool. Univ. Michigan, No.
+     594:1-15, pls. 1-3.
+
+DUELLMAN, W. E., and SCHWARTZ, A.
+
+     1958. Amphibians and reptiles of southern Florida. Bull.
+     Florida State Mus., vol. 3 (5):181-324.
+
+DUNN, E. R.
+
+     1942. The American caecilians. Bull. Mus. Comp. Zool., vol.
+     91 (6):439-540.
+
+DURHAM, J. W., ARELLANO, A. R. V., and PECK, JR., J. H.
+
+     1952. No Cenozoic Tehuantepec seaways. Bull. Geol. Soc.
+     Amer., vol. 63:1245.
+
+FIRSCHEIN, I. L.
+
+     1950. A new toad from Mexico with a redefinition of the
+     _cristatus_ group. Copeia, 1950 (2):81-87, pl. 1.
+
+     1954. Definition of some little-understood members of the
+     leptodactylid genus _Syrrhophus_, with a description of a
+     new species. Copeia, 1954 (1):48-58.
+
+FIRSCHEIN, I. L., and SMITH, H. M.
+
+     1957. A high-crested race of toad (_Bufo valliceps_) and
+     other noteworthy reptiles and amphibians from southern
+     Mexico. Herpetologica, vol. 13 (3):219-222.
+
+FUGLER, C. M., and WEBB, R. G.
+
+     1957. Some noteworthy reptiles and amphibians from the
+     states of Oaxaca and Veracruz. Herpetologica, vol. 13
+     (2):103-108.
+
+GLOYD, H. K.
+
+     1940. The rattlesnakes, genera _Sistrurus_ and _Crotalus_.
+     Chicago Acad. Sci. Special Publ., No. 4, vii + 266 pp., pls.
+     1-31.
+
+GOIN, C. J.
+
+     1958. Comments upon the origin of the herpetofauna of
+     Florida. Quart. Jour. Florida Acad. Sci., vol. 21 (1):61-70.
+
+GOLDMAN, E. A.
+
+     1951. Biological investigations in Mexico. Smithsonian Misc.
+     Publ., vol. 115, xiii + 476 pp., pls. 1-71.
+
+GOODNIGHT, C. J., and GOODNIGHT, M. L.
+
+     1956. Some observations in a tropical rain forest in
+     Chiapas, Mexico. Ecology, vol. 37 (1):139-150.
+
+GRISCOM, L.
+
+     1932. The distribution of bird-life in Guatemala. Bull.
+     Amer. Mus. Nat. Hist., vol. 64:1-439.
+
+     1950. Distribution and origin of the birds of Mexico. Bull.
+     Mus. Comp. Zool., vol. 103:341-382.
+
+HARTWEG, N., and OLIVER, J. A.
+
+     1940. A contribution to the herpetology of the Isthmus of
+     Tehuantepec. IV. An annotated list of the amphibians and
+     reptiles collected on the Pacific slope during the summer of
+     1936. Misc. Publ. Mus. Zool. Univ. Michigan, No. 47:1-31.
+
+HUBBELL, T. H.
+
+     1954. Relationships and distribution of _Mycotrupes_. In The
+     burrowing beetles of the genus _Mycotrupes_, Olson, A. L.,
+     Hubbell, T. H., and Howden, H. F. Misc. Publ. Mus. Zool.
+     Univ. Michigan, No. 84:1-59, pls. 1-8.
+
+HUTCHINSON, G. E., PATRICK, R., and DEEVEY, E. S.
+
+     1956. Sediments of Lake Patzcuaro, Michoacan, Mexico. Bull.
+     Geol. Soc. Amer., vol. 67:1491-1504.
+
+LANGEBARTEL, D. A., and SMITH, P. W.
+
+     1959. Noteworthy records of amphibians and reptiles from
+     eastern Mexico. Herpetologica, vol. 15 (1):27-29.
+
+MARTIN, P. S.
+
+     1958. Pleistocene ecology and biogeography of North America.
+     Zoogeography. Amer. Assoc. Advanc. Sci., Publ. No.
+     51:375-420.
+
+MARTIN, P. S., and HARRELL, B. E.
+
+     1957. The Pleistocene history of temperate biotas in Mexico
+     and eastern United States. Ecology, vol. 38:468-480.
+
+OLIVER, J. A.
+
+     1948. The relationships and zoogeography of the genus
+     _Thalerophis_ Oliver. Bull. Amer. Mus. Nat. Hist., vol.
+     92:157-280, pls. 16-19.
+
+OLSON, E. C., and MCGREW, P. O.
+
+     1941. Mammalian fauna from the Pliocene of Honduras. Bull.
+     Geol. Soc. Amer., vol. 52:1219-1244.
+
+RUTHVEN, A. G.
+
+     1912. The amphibians and reptiles collected by the
+     University of Michigan--Walker Expedition in southern Vera
+     Cruz, Mexico. Zool. Jahrbuch, vol. 32 (4):295-332, pls.
+     6-11.
+
+SCHUCHERT, C.
+
+     1935. Historical geology of the Antillean-Caribbean region.
+     New York, xxvi + 811 pp.
+
+SEARS, P. B., FOREMAN, F., and CLISBY, K. H.
+
+     1955. Palynology in southern North America. Bull. Geol. Soc.
+     Amer., vol. 66:471-530.
+
+SHANNON, F. A., and WERLER, J.
+
+     1955. Notes on amphibians of the Los Tuxtlas Range of
+     Veracruz, Mexico. Trans. Kansas Acad. Sci., vol. 58
+     (3):360-386.
+
+SHREVE, B.
+
+     1957. Reptiles and amphibians from the Selva Lacandona. _In_
+     Biological Investigations in the Selva Lacandona, Chiapas,
+     Mexico. Paynter, R. A. (editor). Bull. Mus. Comp. Zool.,
+     vol. 116 (4):193-298.
+
+SMITH, H. M.
+
+     1947. Notes on Mexican amphibians and reptiles. Jour.
+     Washington Acad. Sci., vol. 37:408-412.
+
+SMITH, H. M., and LAUFE, L. E.
+
+     1946. A summary of Mexican Lizards of the genus _Ameiva_.
+     Univ. Kansas Sci. Bull., vol. 31 (2):7-73.
+
+SMITH, H. M., and TAYLOR, E. H.
+
+     1950. An annotated checklist and key to the reptiles of
+     Mexico exclusive of the snakes. Bull. U. S. Natl. Mus., No.
+     199, v + 253 pp.
+
+STIRTON, R. A.
+
+     1954. Late Miocene mammals from Oaxaca, Mexico. Amer. Jour.
+     Sci., No. 252:634-638.
+
+STUART, L. C.
+
+     1935. A contribution to a knowledge of the herpetology of a
+     portion of the savanna region of central Peten, Guatemala.
+     Misc. Publ. Mus. Zool. Univ. Michigan, No. 29:1-56, pls.
+     1-4.
+
+     1941. Studies of Neotropical Colubridae VIII. A revision of
+     the genus _Dryadophis_ Stuart, 1939. Misc. Publ. Mus. Zool.
+     Univ. Michigan, No. 49:1-106, pls. 1-4.
+
+     1951. The herpetofauna of the Guatemalan Plateau, with
+     special reference to its distribution on the southwestern
+     highlands. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+     No. 49:1-71, pls. 1-7.
+
+     1954. A description of a subhumid corridor across northern
+     Central America, with comments on its herpetofaunal
+     indicators. Contrib. Lab. Vertebrate Biol., Univ. Michigan,
+     No. 65:1-26, pls. 1-6.
+
+     1958. A study of the herpetofauna of the Uaxactun-Tikal area
+     of northern El Peten, Guatemala. Contrib. Lab. Vertebrate
+     Biol., Univ. Michigan, No. 75:1-30.
+
+TAYLOR, E. H.
+
+     1940. New species of Mexican Anura. Univ. Kansas Sci. Bull.,
+     vol. 26 (11):385-405.
+
+     1941. New amphibians from the Hobart M. Smith Mexican
+     collections. Univ. Kansas Sci. Bull., vol. 27 (8):141-167.
+
+     1942. The frog genus _Diaglena_ with a description of a new
+     species. Univ. Kansas Sci. Bull., vol. 28 (4):57-65.
+
+     1943a. A new _Hylella_ from Mexico. Proc. Biol. Soc.
+     Washington, vol. 56:49-52.
+
+     1943b. Herpetological novelties from Mexico. Univ. Kansas
+     Sci. Bull., vol. 29 (8):343-361.
+
+TAYLOR, E. H., and SMITH, H. M.
+
+     1945. Summary of the collections of amphibians made in
+     Mexico under the Walter Rathbone Bacon Traveling
+     Scholarship. Proc. U. S. Natl. Mus., vol. 95:521-613, pls.
+     18-32.
+
+TRASK, P. D., PHLEGER, F. B., and STETSON, H. C.
+
+     1947. Recent changes in sedimentation in the Gulf of Mexico.
+     Science, vol. 106:460-461.
+
+WEYL, R.
+
+     1955. Vestigios de una glaciacion del Pleistoceno en la
+     Cordillera de Talamanca, Costa Rica, A. C. Informe
+     Trimestral, Inst. Geog. de Costa Rica, pp. 9-32.
+
+WHITE, S. E.
+
+     1956. Probable substages of glaciation on Ixtaccihuatl,
+     Mexico. Jour. Geol., vol. 64:289-295.
+
+WILLIAMS, L.
+
+     1939. Arboles y arbustos del Istmos de Tehuantepec, Mexico.
+     Lilloa., vol. 4:137-171.
+
+_Transmitted May 23, 1960._
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY
+
+
+Institutional libraries interested in publications exchange may obtain
+this series by addressing the Exchange Librarian, University of Kansas
+Library, Lawrence, Kansas. Copies for individuals, persons working in a
+particular field of study, may be obtained by addressing instead the
+Museum of Natural History, University of Kansas, Lawrence, Kansas.
+There is no provision for sale of this series by the University
+Library, which meets institutional requests, or by the Museum of
+Natural History, which meets the requests of individuals. However, when
+individuals request copies from the Museum, 25 cents should be
+included, for each separate number that is 100 pages or more in length,
+for the purpose of defraying the costs of wrapping and mailing.
+
+* An asterisk designates those numbers of which the Museum's supply
+(not the Library's supply) is exhausted. Numbers published to date, in
+this series, are as follows:
+
+ Vol. 1.  Nos. 1-26 and index. Pp. 1-638, 1946-1950.
+
+*Vol. 2.  (Complete) Mammals of Washington. By Walter W. Dalquest.
+             Pp. 1-444, 140 figures in text. April 9, 1948.
+
+ Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and
+             distribution. By Rollin H. Baker. Pp. 1-359, 16 figures
+             in text. June 12, 1951.
+
+         *2. A quantitative study of the nocturnal migration of birds.
+             By George H. Lowery, Jr. Pp. 361-472, 47 figures in text.
+             June 29, 1951.
+
+          3. Phylogeny of the waxwings and allied birds. By M. Dale
+             Arvey. Pp. 473-530, 49 figures in text, 13 tables.
+             October 10, 1951.
+
+          4. Birds from the state of Veracruz, Mexico. By George H.
+             Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7
+             figures in text, 2 tables. October 10, 1951.
+
+          Index. Pp. 651-681.
+
+*Vol. 4.  (Complete) American weasels. By E. Raymond Hall. Pp. 1-466,
+             41 plates, 31 figures in text. December 27, 1951.
+
+ Vol. 5.  Nos. 1-37 and index. Pp. 1-676, 1951-1953.
+
+*Vol. 6.  (Complete) Mammals of Utah, _taxonomy and distribution_. By
+             Stephen D. Durrant. Pp. 1-549, 91 figures in text, 80
+             tables. August 10, 1952.
+
+ Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73
+             figures in text, 37 tables. August 25, 1952.
+
+          2. Ecology of the opossum on a natural area in northeastern
+             Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp.
+             305-338, 5 figures in text. August 24, 1953.
+
+          3. The silky pocket mice (Perognathus flavus) of Mexico. By
+             Rollin H. Baker. Pp. 339-347, 1 figure in text. February
+             15, 1954.
+
+          4. North American jumping mice (Genus Zapus). By Philip H.
+             Krutzsch. Pp. 349-472, 47 figures in text, 4 tables.
+             April 21, 1954.
+
+          5. Mammals from Southeastern Alaska. By Rollin H. Baker and
+             James S. Findley. Pp. 473-477. April 21, 1954.
+
+          6. Distribution of Some Nebraskan Mammals. By J. Knox Jones,
+             Jr. Pp. 479-487. April 21, 1954.
+
+          7. Subspeciation in the montane meadow mouse. Microtus
+             montanus, in Wyoming and Colorado. By Sydney Anderson.
+             Pp. 489-506, 2 figures in text. July 23, 1954.
+
+          8. A new subspecies of bat (Myotis velifer) from southeastern
+             California and Arizona. By Terry A. Vaughan. Pp. 507-512.
+             July 23, 1954.
+
+          9. Mammals of the San Gabriel mountains of California. By
+             Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12
+             tables. November 15, 1954.
+
+         10. A new bat (Genus Pipistrellus) from northeastern Mexico.
+             By Rollin H. Baker. Pp. 583-586. November 15, 1954.
+
+         11. A new subspecies of pocket mouse from Kansas. By E.
+             Raymond Hall. Pp. 587-590. November 15, 1954.
+
+         12. Geographic variation in the pocket gopher, Cratogeomys
+             castanops, in Coahuila, Mexico. By Robert J. Russell and
+             Rollin H. Baker. Pp. 591-608. March 15, 1955.
+
+         13. A new cottontail (Sylvilagus floridanus) from northeastern
+             Mexico. By Rollin H. Baker. Pp. 609-612. April 8, 1955.
+
+         14. Taxonomy and distribution of some American shrews. By
+             James S. Findley. Pp. 613-618. June 10, 1955.
+
+         15. The pigmy woodrat, Neotoma goldmani, its distribution and
+             systematic position. By Dennis G. Rainey and Rollin H.
+             Baker. Pp. 619-624. 2 figures in text. June 10, 1955.
+
+          Index. Pp. 625-651.
+
+ Vol. 8.  1. Life history and ecology of the five-lined skink, Eumeces
+             fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in
+             text. September 1, 1954.
+
+          2. Myology and serology of the Avian Family Fringillidae, a
+             taxonomic study. By William B. Stallcup. Pp. 157-211, 23
+             figures in text, 4 tables. November 15, 1954.
+
+          3. An ecological study of the collared lizard (Crotaphytus
+             collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in
+             text. February 10, 1956.
+
+          4. A field study of the Kansas ant-eating frog, Gastrophryne
+             olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in
+             text. February 10, 1956.
+
+          5. Check-list of the birds of Kansas. By Harrison B. Tordoff.
+             Pp. 307-359, 1 figure in text. March 10, 1956.
+
+          6. A population study of the prairie vole (Microtus
+             ochrogaster) in northeastern Kansas. By Edwin P. Martin.
+             Pp. 361-416, 19 figures in text. April 2, 1956.
+
+          7. Temperature responses in free-living amphibians and
+             reptiles of northeastern Kansas. By Henry S. Fitch. Pp.
+             417-476, 10 figures in text, 6 tables. June 1, 1956.
+
+          8. Food of the crow, Corvus brachyrhynchos Brehm, in
+             south-central Kansas. By Dwight Platt. Pp. 477-498, 4
+             tables. June 8, 1956.
+
+          9. Ecological observations on the woodrat, Neotoma floridana.
+             By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3
+             figures in text. June 12, 1956.
+
+         10. Eastern woodrat, Neotoma floridana: Life history and
+             ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13
+             figures in text. August 15, 1956.
+
+         Index. Pp. 647-675.
+
+ Vol. 9.  1. Speciation of the wandering shrew. By James S. Findley.
+             Pp. 1-68, 18 figures in text. December 10, 1955.
+
+          2. Additional records and extensions of ranges of mammals
+             from Utah. By Stephen D. Durrant, M. Raymond Lee, and
+             Richard M. Hansen. Pp. 69-80. December 10, 1955.
+
+          3. A new long-eared myotis (Myotis evotis) from northeastern
+             Mexico. By Rollin H. Baker and Howard J. Stains. Pp.
+             81-84. December 10, 1955.
+
+          4. Subspeciation in the meadow mouse, Microtus pennsylvanicus,
+             in Wyoming. By Sydney Anderson. Pp. 85-104, 2 figures in
+             text. May 10, 1956.
+
+          5. The condylarth genus Ellipsodon. By Robert W. Wilson.
+             Pp. 105-116, 6 figures in text. May 19, 1956.
+
+          6. Additional remains of the multituberculate genus
+             Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures
+             in text. May 19, 1956.
+
+          7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp.
+             125-335, 75 figures in text. June 15, 1956.
+
+          8. Comments on the taxonomic status of Apodemus peninsulae,
+             with description of a new subspecies from North China. By
+             J. Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1
+             table. August 15, 1956.
+
+          9. Extensions of known ranges of Mexican bats. By Sydney
+             Anderson. Pp. 347-351. August 15, 1956.
+
+         10. A new bat (Genus Leptonycteris) from Coahuila. By Howard
+             J. Stains. Pp. 353-356. January 21, 1957.
+
+         11. A new species of pocket gopher (Genus Pappogeomys) from
+             Jalisco, Mexico. By Robert J. Russell. Pp. 357-361.
+             January 21, 1957.
+
+         12. Geographic variation in the pocket gopher, Thomomys
+             bottae, in Colorado. By Phillip M. Youngman. Pp. 363-384,
+             7 figures in text. February 21, 1958.
+
+         13. New bog lemming (genus Synaptomys) from Nebraska. By J.
+             Knox Jones, Jr. Pp. 385-388. May 12, 1958.
+
+         14. Pleistocene bats from San Josecito Cave, Nuevo Leon,
+             Mexico. By J. Knox Jones, Jr. Pp. 389-396. December 19,
+             1958.
+
+         15. New Subspecies of the rodent Baiomys from Central America.
+             By Robert L. Packard. Pp. 397-404. December 19, 1958.
+
+         16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson.
+             Pp. 405-414, 1 figure in text. May 20, 1959.
+
+         17. Distribution, variation, and relationships of the montane
+             vole, Microtus montanus. By Emil K. Urban. Pp. 415-511.
+             12 figures in text, 2 tables. August 1, 1959.
+
+         18. Conspecificity of two pocket mice, Perognathus goldmani
+             and P. artus. By E. Raymond Hall and Marilyn Bailey
+             Ogilvie. Pp. 513-518, 1 map. January 14, 1960.
+
+         19. Records of harvest mice, Reithrodontomys, from Central
+             America, with description of a new subspecies from
+             Nicaragua. By Sydney Anderson and J. Knox Jones, Jr. Pp.
+             519-529. January 14, 1960.
+
+         20. Small carnivores from San Josecito Cave (Pleistocene),
+             Nuevo Leon, Mexico. By E. Raymond Hall. Pp. 531-538, 1
+             figure in text. January 14, 1960.
+
+         21. Pleistocene pocket gophers from San Josecito Cave, Nuevo
+             Leon, Mexico. By Robert J. Russell. Pp. 539-548, 1 figure
+             in text. January 14, 1960.
+
+         22. Review of the insectivores of Korea. By J. Knox Jones,
+             Jr., and David H. Johnson. Pp. 549-578. February 23, 1960.
+
+         23. Speciation and evolution of the pygmy mice, genus Baiomys.
+             By Robert L. Packard. Pp. 579-670, 4 plates, 12 figures in
+             text. June 16, 1960.
+
+         Index Pp. 671-690.
+
+Vol. 10.  1. Studies of birds killed in nocturnal migration. By
+             Harrison B. Tordoff and Robert M. Mengel. Pp. 1-44, 6
+             figures in text, 2 tables. September 12, 1956.
+
+          2. Comparative breeding behavior of Ammospiza caudacuta and
+             A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates,
+             1 figure. December 20, 1956.
+
+          3. The forest habitat of the University of Kansas Natural
+             History Reservation. By Henry S. Fitch and Ronald R.
+             McGregor. Pp. 77-127, 2 plates, 7 figures in text, 4
+             tables. December 31, 1956.
+
+          4. Aspects of reproduction and development in the prairie
+             vole (Microtus ochrogaster). By Henry S. Fitch. Pp.
+             129-161, 8 figures in text, 4 tables. December 19, 1957.
+
+          5. Birds found on the Arctic slope of northern Alaska. By
+             James W. Bee. Pp. 163-211, pls. 9-10, 1 figure in text.
+             March 12, 1958.
+
+          6. The wood rats of Colorado: distribution and ecology. By
+             Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures
+             in text, 35 tables. November 7, 1958.
+
+          7. Home ranges and movements of the eastern cottontail in
+             Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3
+             figures in text. May 4, 1959.
+
+          8. Natural history of the salamander, Aneides hardyi. By
+             Richard F. Johnston and Schad Gerhard. Pp. 573-585.
+             October 8, 1959.
+
+          9. A new subspecies of lizard, Cnemidophorus sacki, from
+             Michoacan, Mexico. By William E. Duellman. Pp. 587-598,
+             2 figures in text. May 2, 1960.
+
+         10. A taxonomic study of the Middle American Snake, Pituophis
+             deppei. By William E. Duellman. Pp. 599-610, 1 plate, 1
+             figure in text. May 2, 1960.
+
+         Index Pp. 611-626.
+
+Vol. 11.  1. The systematic status of the colubrid snake, Leptodeira
+             discolor Guenther. By William E. Duellman. Pp. 1-9, 4
+             figs. July 14, 1958.
+
+          2. Natural history of the six-lined racerunner, Cnemidophorus
+             sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figs., 9
+             tables. September 19, 1958.
+
+          3. Home ranges, territories, and seasonal movements of
+             vertebrates of the Natural History Reservation. By Henry
+             S. Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3
+             tables. December 12, 1958.
+
+          4. A new snake of the genus Geophis from Chihuahua, Mexico.
+             By John M. Legler. Pp. 327-334, 2 figures in text.
+             January 28, 1959.
+
+          5. A new tortoise, genus Gopherus, from north-central
+             Mexico. By John M. Legler. Pp. 335-343. April 24, 1959.
+
+          6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By
+             Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in
+             text, 10 tables. May 6, 1959.
+
+          7. Fishes of the Big Blue River Basin, Kansas. By W. L.
+             Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5
+             tables. May 8, 1959.
+
+          8. Birds from Coahuila, Mexico. By Emil K. Urban. Pp.
+             443-516. August 1, 1959.
+
+          9. Description of a new softshell turtle from the
+             southeastern United States. By Robert G. Webb. Pp.
+             517-525, 2 pls., 1 figure in text, August 14, 1959.
+
+         10. Natural history of the ornate box turtle, Terrapene
+             ornata ornata Agassiz. By John M. Legler. Pp. 527-669,
+             16 pls., 29 figures in text. March 7, 1960.
+
+         Index will follow.
+
+Vol. 12.  1. Functional morphology of three bats: Eumops, Myotis,
+             Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24
+             figures in text, July 8, 1959.
+
+          2. The ancestry of modern Amphibia: a review of the
+             evidence. By Theodore H. Eaton, Jr. Pp. 155-180, 10
+             figures in text. July 10, 1959.
+
+          3. The baculum in microtine rodents. By Sydney Anderson.
+             Pp. 181-216, 49 figures in text. February 19, 1960.
+
+          4. A new order of fishlike Amphibia from the Pennsylvanian
+             of Kansas. By Theodore H. Eaton, Jr., and Peggy Lou
+             Stewart. Pp. 217-240, 12 figures in text. May 2, 1960.
+
+          More numbers will appear in volume 12.
+
+Vol. 13.  1. Five natural hybrid combinations in minnows (Cyprinidae).
+             By Frank B. Cross and W. L. Minckley. Pp. 1-18. June 1,
+             1960.
+
+          2. A distributional study of the amphibians of the isthmus
+             of Tehuantepec, Mexico. By William E. Duellman.
+             Pp. 19-72, pls. 1-8, 3 figs. August 16, 1960.
+
+          More numbers will appear in volume 13.
+
+       *       *       *       *       *
+
+
+Transcriber's Notes
+
+
+Page 26: Changed "19. Cosaleacaque" to "19. Cosoleacaque".
+
+Page 30: Changed "Brysonima crassifolia" to "Byrsonima crassifolia".
+
+Page 34: Changed "long. 95' 29 deg.;" to "long. 95 deg. 29';".
+
+Page 35: Changed "Matias Romera" to "Matias Romero".
+
+Page 47: Changed "kown" to "known".
+
+Pages 50 and 59: Changed "axills" to "axils".
+
+Plate 1, Fig. 2: Changed "Veracuz" to "Veracruz".
+
+Page 53: Changed "valadity" to "validity".
+
+Page 61, Table 1: Changed male symbol to "(Male)" (plain text version).
+
+Page 67: Changed "refering" to "referring".
+
+Page 68: Changed "survided" to "survived".
+
+Page 71: Changed "subhimid" to "subhumid" and "Amerca" to "America".
+
+Moved University of Kansas Publications list to end of report.
+Vol. 9, No. 12: Changed pages from "363-387" to "363-384".
+Vol. 10, No. 10: Changed pages from "599-612" to "599-610".
+
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of A Distributional Study of the
+Amphibians of the Isthmus of Tehuantepec, Mexico, by William E. Duellman
+
+*** END OF THIS PROJECT GUTENBERG EBOOK A DISTRIBUTIONAL STUDY OF ***
+
+***** This file should be named 38440.txt or 38440.zip *****
+This and all associated files of various formats will be found in:
+        http://www.gutenberg.org/3/8/4/4/38440/
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
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+http://www.pgdp.net
+
+
+Updated editions will replace the previous one--the old editions
+will be renamed.
+
+Creating the works from public domain print editions means that no
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