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+*** START OF THE PROJECT GUTENBERG EBOOK 42720 ***
+
+                Speciation in the Brazilian Spiny Rats
+                (Genus Proechimys, Family Echimyidae)
+
+                                  BY
+                             JOÃO MOOJEN
+
+
+                  University of Kansas Publications
+                      Museum of Natural History
+
+        Volume 1, No. 19, pp. 301-406, 140 figures in text
+                          December 10, 1948
+
+
+                        University of Kansas
+                              LAWRENCE
+                                1948
+
+
+
+
+    UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+        Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
+                          Edward H. Taylor
+
+     Volume 1, No. 19, pp. 301-406, 1 plate, 140 figures in text
+
+                    Published December 10, 1948
+
+
+                        UNIVERSITY OF KANSAS
+                          Lawrence, Kansas
+
+
+                             PRINTED BY
+                  FERD VOILAND, JR., STATE PRINTER
+                           TOPEKA, KANSAS
+                                1948
+
+                               22-3343
+
+
+
+
+               Speciation in the Brazilian Spiny Rats
+               (Genus Proechimys, Family Echimyidae)
+
+                                  By
+                             JOÃO MOOJEN
+
+
+
+
+CONTENTS
+
+
+                                                           PAGE
+  INTRODUCTION                                              305
+
+  METHODS AND TERMINOLOGY                                   305
+
+  ACKNOWLEDGMENTS                                           308
+
+  PALEONTOLOGY                                              308
+
+  SPECIATION                                                311
+      Subgeneric variation                                  312
+      Specific variation in the subgenus _Proechimys_       314
+      Subspecific variation in the subgenus _Proechimys_    317
+      Specific variation in the subgenus _Trinomys_         320
+      Subspecific variation in the subgenus _Trinomys_      322
+
+  TAXONOMIC CHARACTERS                                      323
+      Size and proportions of external parts                323
+      Pelage                                                324
+      Skull                                                 326
+      Incisive foramen                                      326
+      Teeth                                                 327
+
+  HABITS                                                    330
+
+  CHANGES WITH AGE                                          331
+
+  Genus PROECHIMYS                                          333
+
+  ARTIFICIAL KEY TO SUBGENERA AND SPECIES                   334
+
+  Subgenus PROECHIMYS                                       338
+      _Proechimys goeldii_                                  338
+          _Proechimys goeldii steerei_                      338
+          _Proechimys goeldii goeldii_                      340
+      _Proechimys semispinosus_                             342
+          _Proechimys semispinosus liminalis_               343
+          _Proechimys semispinosus amphichoricus_           344
+          _Proechimys semispinosus kermiti_                 345
+      _Proechimys longicaudatus_                            346
+          _Proechimys longicaudatus brevicauda_             349
+          _Proechimys longicaudatus boimensis_              350
+          _Proechimys longicaudatus longicaudatus_          351
+          _Proechimys longicaudatus leucomystax_            352
+          _Proechimys longicaudatus roberti_                353
+      _Proechimys guyannensis_                              355
+          _Proechimys guyannensis villicauda_               355
+          _Proechimys guyannensis ribeiroi_                 361
+          _Proechimys guyannensis hyleae_                   361
+          _Proechimys guyannensis nesiotes_                 363
+          _Proechimys guyannensis leioprimna_               364
+          _Proechimys guyannensis oris_                     365
+          _Proechimys guyannensis arescens_                 366
+          _Proechimys guyannensis riparum_                  367
+          _Proechimys guyannensis arabupu_                  369
+
+  Subgenus TRINOMYS                                         369
+      _Proechimys dimidiatus_                               371
+      _Proechimys iheringi_                                 373
+          _Proechimys iheringi iheringi_                    378
+          _Proechimys iheringi bonafidei_                   378
+          _Proechimys iheringi gratiosus_                   379
+          _Proechimys iheringi panema_                      380
+          _Proechimys iheringi denigratus_                  381
+          _Proechimys iheringi paratus_                     382
+      _Proechimys setosus_                                  384
+          _Proechimys setosus setosus_                      385
+          _Proechimys setosus elegans_                      387
+      _Proechimys albispinus_                               388
+          _Proechimys albispinus albispinus_                390
+          _Proechimys albispinus sertonius_                 391
+
+  INCERTA SEDIS                                             392
+      _Proechimys myosuros_                                 392
+
+  CONCLUSIONS                                               393
+
+  TABLE OF MEASUREMENTS                                     395
+
+  LITERATURE CITED                                          400
+
+
+[Illustration: FIG. 1. _Proechimys dimidiatus_ (Günther). Live female on
+left and male on right. ×1/2. From Tingua, Nova Iguassú, Rio de Janeiro,
+Brazil. Photographed in spring (August or September) of 1942 by
+author.]
+
+
+
+
+INTRODUCTION
+
+
+The spiny-rats included in the genus _Proechimys_ are common in almost
+every forest of South America above the Tropic of Capricorn, and in
+Central America northward to approximately 12° N, in Nicaragua. In size
+and proportions they are similar to the brown rat _Rattus norvegicus_
+but actually they belong to a very different suborder of rodents--the
+Hystricomorpha. The hystricomorphs are represented in South America by a
+large variety of animals, of which capybaras, agoutis and cavies are
+common representatives.
+
+The pelage of the spiny-rats has a large number of flattened, spinelike
+hairs, especially on the back. The color ranges through different tints
+and shades of reddish-brown more or less evenly distributed on the upper
+parts; the underparts are usually pure white, sharply contrasting with
+the brown color above. The tail is bicolored, brown above and white
+below.
+
+The spiny-rats live in forests of different types, generally in the
+proximity of water. Shelter is usually procured under boulders, stumps
+or masses of roots. The reproductive rate is low; on the average, there
+are only two young per litter and only two litters per year.
+
+Sixty-odd names have been given to species and subspecies of
+_Proechimys_ in the last hundred and fifty years and no serious revision
+of the taxonomy of the genus was undertaken in the last century. The
+purpose of the present work is to provide means of understanding species
+and subspecies within the genus and to describe the different kinds
+known to occur within the confines of Brazil.
+
+
+
+
+METHODS AND TERMINOLOGY
+
+
+      PELAGE.--It was found advisable to use a standardized nomenclature
+      for hairs. The names here proposed are a choice of those used in
+      the literature, with the suffix "_form_" as an element of
+      uniformity. I feel that it would be advantageous if everyone
+      adopted a similar universal system in mammalogy.
+
+      The names listed below are used as nouns and are considered as
+      English versions which could easily be adapted to different
+      languages. These names may be complemented with adjectives as
+      needed. Examples are lanceolate aristiforms, spinous aristiforms,
+      and woolly setiforms.
+
+      _Aristiforms:_ The most conspicuously developed hairs in a
+      three-layered pelage or the corresponding hairs in a simpler
+      pelage. Names previously used for these hairs are: guard hair,
+      leithaar and jarre.
+
+      _Setiforms:_ Common to all species and most numerous throughout the
+      pelage; second in conspicuousness, being the dominant hairs in the
+      middle layer. Synonyms are: over hairs, grannenhaare and soies.
+
+      _Villiforms:_ The smallest hairs in the three-layered pelage.
+      Synonyms are: underfur, wollhaar and duvet.
+
+      _Vibrissiforms:_ The vibrissae proper, or any typically sensory
+      hair.
+
+      TEETH.--The tritubercular nomenclature was abandoned because of
+      overwhelming difficulties; more research on the Hystricomorpha is
+      certainly needed before the tritubercular nomenclature can be
+      applied with confidence. The following names are used for features
+      of the molariform teeth:
+
+      _Main fold:_ The inner or lingual fold in the upper molariform
+      teeth and outer or labial fold in the lower molariform teeth.
+
+      _Counterfold:_ Any outer or labial fold in the upper or any inner
+      or lingual fold in the lower molariform teeth.
+
+      For incisors Thomas (1921:141) is followed: _opisthodont_,
+      _orthodont_ and _proodont_ depending on the angle between the
+      exposed part of incisors and the ventral surface of the rostrum.
+
+      The capital letters P and M designate premolars and molars,
+      respectively, of the upper jaws; lower case letters p and m
+      designate corresponding teeth in the lower jaws.
+
+      MEASUREMENTS.--Measurements of skins were used only when provided
+      by the collector. The length of the hind-foot is intended to be
+      always _cum unguis_, but in a few instances it is impossible to be
+      sure whether the collector included the nail. Length of tail was
+      used only when the tail seemed not to be mutilated. Ear
+      measurements taken by collectors are scarce. In spite of the
+      apparent usefulness of length of ear, it was found to be
+      inadvisable to take the measurement on the dry skins.
+
+      The following measurements of the skull are used in the tables:
+
+      _Greatest length:_ From the anteriormost part of the nasals to the
+      posteriormost part of the supraoccipital.
+
+      _Condylo-incisive length:_ From the anterior face of one incisor,
+      at the alveolus, to the posteriormost part of the exoccipital
+      condyle of the same side.
+
+      _Zygomatic breadth:_ Maximum distance across zygomata in a plane
+      perpendicular to longitudinal axis of the skull.
+
+      _Length of nasals:_ Maximum length of one or both, whichever is
+      the greater.
+
+      _Interorbital constriction:_ Least width between the orbits on top
+      of the skull.
+
+      _Palatilar length:_ From the posterior face of an incisor, at the
+      alveolus, to the nearest part of the posterior edge of the
+      palatine bone.
+
+      _Crown length of cheekteeth:_ From the anterior border of P4 to
+      the posterior border of M3.
+
+      In the accounts of species, measurements of aristiforms and
+      setiforms are used. The hairs measured were taken from the
+      middorsal region and outer thighs, and the measurements are means.
+
+      All specimens of which measurements are here recorded, as for
+      example in the tables, are fully adult; each specimen shows some
+      wear on each of the four upper molariform teeth unless otherwise
+      indicated.
+
+      Capitalized color terms are after Ridgway "Color Standards and
+      Color Nomenclature," Washington, D. C., U. S. A., 1912. One
+      setiform was taken from the animal and placed over the rectangles
+      in Ridgway's charts and the examination made under a microscope
+      with low (×7) magnification and natural light. This method was
+      found to give the most satisfactory results.
+
+The following abbreviations are used for names of institutions:
+
+     AMNH--American Museum of Natural History.
+     CNHM--Chicago Natural History Museum.
+     DZ--Departamento de Zoologia da Secretaria de Agricultura, São
+         Paulo, Brazil.
+     MCZ--Museum of Comparative Zoology at Harvard College.
+     MN--Museu Nacional, Brazil.
+     MZ--Museum of Zoology, University of Michigan.
+     SEPFA--Serviço de Estudos e Pesquisas sobre a Febre Amarela, Brazil.
+     USNM--United States National Museum.
+     UZM--Universitets Zoologiske Museum, Copenhagen.
+
+
+
+
+ACKNOWLEDGMENTS
+
+
+      Approximately two thousand skins and skulls were assembled at the
+      Museum of Natural History, University of Kansas, through the
+      coöperation of the authorities in the various institutions of North
+      America, Brazil and Denmark, as listed immediately above. This
+      comprehensive material was used to obtain a more complete
+      understanding of the group, and for the loan of these specimens I
+      am extremely grateful to the authorities of each of the
+      institutions.
+
+      First of all I acknowledge the encouragement given me in the
+      _Proechimys_ project by Heloisa Alberto Torres, Director of the
+      Museu Nacional, Rio de Janeiro. I extend my thanks also to Stephen
+      D. Durrant, of the University of Utah, for helpful corrections in
+      the preparation of the manuscript; to Mrs. Virginia Cassell Unruh,
+      for the preparation of the drawings of the skulls; to Miss Alice
+      M. Bruce for assistance in drawing the maps; and to my daughter,
+      Julieta, for help in assembling data and for typing.
+
+      Dr. Remington Kellogg, Curator of Mammals in the United States
+      National Museum, and the late Dr. Wilfred H. Osgood, formerly
+      Curator Emeritus of the Department of Zoology in the Chicago
+      Natural History Museum, generously permitted me to use their
+      private lists of South American mammals. These lists contain much
+      unpublished data, as for example, proof, in Kellogg's list, that
+      _Proechimys guyannensis_ (E. Geoffroy Saint-Hilaire, 1803)
+      antedates _P. cayennensis_ (Desmarest, 1817). I register here my
+      gratitude to both these zoölogists and acknowledge other critical
+      assistance from Dr. Kellogg.
+
+      The John Simon Guggenheim Memorial Foundation awarded me a
+      fellowship for which I am deeply grateful. This expression of the
+      Foundation's interest in education and good neighborliness made
+      possible the completion of the present paper.
+
+      Finally I desire to express my deepest gratitude to Professor E.
+      Raymond Hall, Director of the Museum of Natural History and
+      Chairman of the Department of Zoology at the University of Kansas
+      whose untiring aid and guidance has enabled me to terminate this
+      study.
+
+
+
+
+PALEONTOLOGY
+
+
+The only known, significant, fossil _Proechimys_ comes from deposits in
+the limestone caves of Lagoa Santa, Minas Gerais, Brazil. These
+deposits, of Late Pleistocene or Recent age, were extensively studied by
+P. W. Lund and the results published in a series of French and Danish
+papers. F. Ameghino (1934:110) studied another fauna from a deposit of
+similar age in the cave of Iporanga, São Paulo, Brazil. _Proechimys_ is
+recorded in his account under the inclusive specific name _fuliginosus_.
+
+The molariform teeth of the fossil described by Lund (1841:pl. 21, fig.
+14) shows its close relationship to the living form _P. s._ _elegans_
+(Lund) which still inhabits the same region. It belongs in the more
+specialized subgenus _Trinomys_ which seems to have been derived from
+_Proechimys_. _Trinomys_ has the main fold in the molars always greatly
+developed and the fold tends to set apart one lamina in the occlusal
+surface. The Lagoa Santa fossil, like some specimens of the living
+subspecies, has a small main fold in P4. However, the main fold is large
+in all upper molars and in the lower molariform teeth which are notably
+specialized in the extreme reduction of the number of counterfolds to
+only one.
+
+One hypothesis concerning the evolution of the genus is that a more
+primitive group of _Proechimys_ lived in all of the Central Plateau of
+Brazil in the Pleistocene Time. The climatic conditions at that time
+might have been such as to support large forests but, since the
+Pleistocene, these climatic conditions may have changed from humid to
+the present drier conditions, which support the dominant, savanna,
+floral climax. Actually the extinct fauna from the caves includes
+animals which have disappeared from the area and now live only in more
+humid areas, as for example _Myocastor_, which has shifted to the
+lowlands to the west and south.
+
+Possibly climatic changes were responsible for the faunal shift from the
+region that is now a plateau in Central Brazil. This climatic change may
+have resulted from the gradual uplift of the eastern part of the
+continent. This uplift prevents part of the trade winds which come from
+the east from carrying the same amount of moisture inland as they did
+previously. In fact, the Andean revolution, even if it occurred as late
+as Late Tertiary, would have had no perceptible influence on the
+amount of water precipitated on the more eastern parts of the continent.
+Oliveira and Leonardos (1943:617) point out that after a Cretaceous
+submersion of the central part of Brazil, there was a general uplift.
+The authors (_op. cit._:689) mention the presence of continental
+Cretaceous deposits in the Central Plateau of Brazil, in support of
+these changes, and state that "pelo menos em certas zonas do litoral a
+elevação do continente prolongou-se até o Pleistoceno."
+
+Berry (1942:373) concluded, among other things, that there was a
+southward extension "in South America of equatorial floras in the lower
+Miocene," and (_op. cit._:372) that ... "east of the Andean Axis in
+the south temperate zone there was a normal mesophytic flora ... instead
+... of present day large steppes."
+
+My idea is that a tropical forest still covered the Central Plateau of
+Brazil in (early?) Pleistocene times and that populations of
+_Proechimys_ of a primitive type, similar to _P. g. steerei_, for
+example, lived in that extensive forest-climax. The gradual uplift of
+the plateau, however, gradually brought about drier conditions in this
+region. As a result a large cliseral change was initiated, which shifted
+the forest-climax to the more humid eastern escarpments and lowlands
+that were gradually being developed, while the savanna climax was being
+established on the plateau. Eventually the effect of the decreasing
+moisture was locally accentuated by the erosion of the sandstones
+(Oliveira and Leonardos, 1943:690) in northeastern Brazil, thus
+depriving it of a natural reservoir of rain water. An arid belt was
+developed which now constitutes an efficient geographic barrier to the
+distribution of many kinds of animals.
+
+One marginal species may have shifted eastward with the forest-climax
+to effect the Recent distribution. The eastern species became completely
+isolated from the main group, accumulated mutations, and evolved into
+the subgeneric type _Trinomys_. The generic trend that gave rise to
+_Trinomys_ probably remained more stable as far as supraspecific changes
+are concerned. The lack of barriers in the distributional area of the
+original group favored the dispersal and submergence of mutations and,
+therefore, there was but little further supraspecific evolution. The
+speciation in both subgenera finally resulted from gradual
+differentiation of varying populations since they show combinations of
+the generic biotypes and possess few truly qualitative characters.
+
+The cliseral changes in the Central Plateau, which developed the dry
+belt, a barrier, might explain the evolution of a few more supraspecific
+groups of mammals, as indicated by the presence of similar forms in the
+Amazonian region and in Southeastern Brazil. Among these _Echimys_ and
+_Phyllomys_, in the same family with _Proechimys_, show differences that
+are parallel to those observed in _Proechimys_. One of these parallel
+changes is the increased lamination of the cheekteeth. Although
+_Echimys_, from the Amazonian region, has upper molariform teeth with
+the four laminae fused, _Phyllomys_ has the four laminae completely
+separated.
+
+None of the genera known from the Upper Oligocene and Miocene of
+Argentine deposits seems to be directly ancestral to _Proechimys_.
+
+
+
+
+SPECIATION
+
+
+The detection of differences of systematic worth between populations of
+animals, represented by skins and skulls, is a step preliminary to
+deducing the factors responsible for the differences. Ordinarily the
+factors which cause heritable differences have to do with geographic
+isolation and adaptation to ecological conditions. When differences in
+the structure of the animal are known, a person is led to speculate on
+the factors which could cause them. For one thing, does the observed
+degree of difference tend to isolate animals possessing the "new"
+character from the other animals? It would seem to me that the isolation
+once started by one of these differences tends to be accentuated with
+time and the difference itself thus then becomes a factor responsible
+for further differentiation.
+
+Whether or not transition from one character to another occurs
+gradually, in its geographic expression, and thus whether or not
+intergradation occurs between two subspecies, can be ascertained by the
+analysis of a series of population-samples appropriately distributed
+geographically. If two characters of systematic worth are known to blend
+in one part of the geographic range of a subgenus, and if the same two
+characters are seen in two other populations, far removed geographically
+from each other and without any samples of annectent populations to
+provide actual evidence of intergradation, then such intergradation is
+to be inferred.
+
+The available collections of _Proechimys_ mostly were made haphazardly
+with the result that there are extensive areas from which no specimens
+as yet are available. Thus, actual proof of intergradation is often
+lacking in areas where it almost certainly occurs. In some extensive
+areas, however, many samples, from relatively regular intervals, have
+been available and they provide genuine proof of intergradation. These
+instances have served as a guide for estimating whether other samples
+should be considered to be full species or instead merely subspecies of
+the same species.
+
+Lack of intergradation in any of the characters may be accepted as the
+criterion of full species. Where two populations occupying the same
+range (sympatric populations) show different qualitative characters,
+they almost certainly do not crossbreed. Furthermore the characters that
+distinguish such kinds of nonintergrading animals are likely to be
+considered as of full specific value when detected in far distant parts
+of the range of the subgenus.
+
+In a genus that is widespread and continuously distributed, it is useful
+to know which characters always distinguish full species and which ones,
+sometimes or always, distinguish only subspecies, since in a population
+from a small island, there is, ordinarily, less individual variation
+than in a corresponding population from the mainland or a larger island;
+under certain circumstances a person might be tempted to give specific
+rank to the population when its characters actually are analogous to
+those separating subspecies elsewhere.
+
+Sometimes it is convenient to recognize species-groups, a systematic
+category without nomenclatural status, intermediate between the species
+and the subgenus. When there are two groups of species not sharply
+separated, including one species whose characters overlap those of each
+of the two groups, it would seem most appropriate to recognize only
+species-groups instead of subgenera. When, on the other hand, the two
+groups of species have mutually exclusive characters and a species with
+intermediate characters is unknown, the two groups of species can
+conveniently be accorded separate subgeneric rank.
+
+
+SUBGENERIC VARIATION
+
+A few characters are common to one group of species and other features
+are common to a second group. The most striking of these features is the
+character of the main fold in the molariform teeth. In one group the
+fold transversely crosses the crown of the tooth and in the other it
+extends scarcely halfway across. No specimen is intermediate in this
+respect. These two groups, furthermore, are separated geographically by
+an important barrier, the arid belt that starts in the northeastern
+littoral of Brazil (Ceará), and that extends south and southwesterly,
+more or less accompanying the São Francisco River in the Plateau, to
+about 20° S. _Proechimys_ is thought not to inhabit this arid belt. At
+the latitude of 20° S the conditions become more suitable for
+_Proechimys_, especially along the rivers which flow eastward, but there
+the Plateau is replaced by mountains: the Serra Geral at the west, and
+Serra da Mantiqueira at the south; these ranges are bare of forests at
+higher elevations. Two groups of species of _Proechimys_ are, therefore,
+kept geographically isolated: one group lives in southeastern Brazil,
+and the other lives in a large area to the west which starts at 21° S in
+Paraguay and Brazil and widens northward and includes, farther west,
+central and northern Brazil and all the South American countries
+above 21° S, as well as Central America northward to southern Nicaragua.
+
+The two groups which are here treated as subgenera may be designated as
+follows:
+
+_Trinomys_--main fold deep: aristiforms well-developed on the rump and
+outer thighs; tail no less than 75 per cent of length of head and body;
+skull without ridges across the parietals; no conspicuous groove for
+transmission of nerve inside infraorbital foramen; molariform teeth
+decreasing in size from premolar to third molar; 1 to 3 counterfolds in
+the molariform teeth.
+
+_Proechimys_--main fold shallow: aristiforms not developed on rump and
+outer thighs; tail less than 75 per cent of length of head and body;
+groove for transmission of nerve present in infraorbital foramen of
+several subspecies; molariform teeth increasing in size from premolar to
+second molar; 2 to 5 counterfolds in molariform teeth.
+
+Most of these characters vary but do not overlap. Subgeneric rank is
+here accorded to the two groups of _Proechimys_ characterized
+immediately above.
+
+The primary cause of the subgeneric differentiation is thought to have
+been geologic changes in the continental area. As already pointed out
+(see Paleontology), decreasing humidity in the Central Plateau of Brazil
+may have caused a migration southwestward of one or more of the species
+along with the forests. Once isolated geographically, the species
+probably differentiated at an accelerated rate.
+
+The fact that a much larger number of subspecies occupies the larger
+geographic range of the subgenus _Proechimys_ would not be sufficient to
+prove that this subgenus, _Proechimys_, is nearer to the primitive group
+than _Trinomys_, the subgenus occupying the smaller range with fewer
+subspecies. The paleontological evolution of the rodents, however,
+consistently points to teeth with a larger number of counterfolds (as
+seen in _Proechimys_) as the primitive condition. The extension of the
+main fold, tending to set apart one lamina in each upper molariform
+tooth, seems to be a specialization; reduction in the size of the head
+and body, increase in length of tail and decreasing size of molars
+posteriorly also may be specializations. The main point, however, is to
+establish if _Trinomys_ is a relic group rather than a "differentiated"
+one. If an intermediate form were known which connected _Trinomys_ with
+one species of _Proechimys_ more than with another or even if _Trinomys_
+itself more closely resembled one of the groups of species of the
+subgenus _Proechimys_ than it did another, we would assume that
+divergence and selection accounted for the subgeneric variation. The
+lack of any such connecting link favors the first idea, namely that
+_Trinomys_ differentiated rapidly with the aid of geographic variation.
+
+If _Trinomys_ is, as I am inclined to consider it, the result of
+"differentiation," its subgeneric features are to be admitted as "new"
+and therefore the most primitive species in the genus should be found in
+the subgenus _Proechimys_.
+
+It is a matter of common sense to admit the two groups considered above
+as subgenera rather than genera. Since the two structural plans were
+established they would, and do, act as different sources of variation.
+On the other hand, the morphological differences do not give the two
+groups an amount of morphological differences that would justify full
+generic rank for each.
+
+
+SPECIFIC VARIATION IN THE SUBGENUS PROECHIMYS
+
+Most of the described forms in the subgenus were initially named as
+distinct full species. More recently, however, in accordance with the
+ideas now prevalent in systematic work, many of the named kinds were
+reduced to the rank of subspecies. Tate first made a geographic
+arrangement (1935:399-400) and later (1939:177-178) provisionally
+synonymised several named kinds of _Proechimys_ with _Proechimys_
+"_cayennensis cayennensis_." A similar tendency was clearly displayed by
+Ellerman (1940:115-122) who allocated 29 names, out of 33 (in the
+subgenus, as here understood), to the species _Proechimys guyannensis_
+and gave full specific rank to four other named kinds. Osgood (1944)
+also had the same viewpoint; that is to say, he appeared to have the
+idea that there were only two full species in the subgenus in
+Brazil--admitting this orally--and consequently he synonymised some full
+species where two or more occurred in the same place, thinking that he
+was dealing with individual, rather than specific, differences.
+Evidently the number of species in the subgenus cannot be great because
+the known kinds show few patterns worthy of specific designation and
+therefore the majority of the existing names should be suspected of
+having no more than subspecific value. Nevertheless none of the above
+writers presented real evidence in support of his arrangement.
+
+Criteria for the recognition of full species are most easily recognized
+where two or more different species live together. In the literature,
+_P. goeldii_ and _P. "oris"_ were mentioned by Thomas (1912:89) as
+having been collected in the same place; _P. mincae_ and _P.
+canicollis_, by H. H. Smith (in Allen, 1904:440); _P._ "_leucomystax_,"
+from Utiarití, by Miranda Ribeiro (1914:42) and _P._ "_longicaudatus_,"
+from the same place, by Allen (1916:569) were other examples. In these,
+and other alleged instances of two or more kinds occurring together,
+detailed study of the specimens concerned was necessary to learn the
+true facts. Also with the opportunity to compare collections from
+several different places, new facts emerged. _P. longicaudatus_, as it
+was conceived of by Allen, was a composite species, but in one locality,
+Utiarití, Ribeiro and Allen actually were dealing with two distinct
+species.
+
+The species, or subspecies belonging to different species, living
+together are: _goeldii_ and _hyleae_, at Fazenda Paraiso; _goeldii_ and
+_riparum_ in Manaus; _boimensis_ and _hyleae_ in Tauarí; _leucomystax_
+and _villicauda_ in Utiarití; _mincae_ and _canicollis_ in Bonda;
+_gularis_ and _hendeei_ on the banks of Rio Napo ("same trap lines,"
+according to P. Hershkovitz, _In Litt._). Study of samples of the above
+named pairs of kinds of _Proechimys_ showed the following specific
+differences: _goeldii_ is large with narrow aristiforms, has a large and
+strongly built skull, with four counterfolds in one or more upper
+molars: _hyleae_ is smaller, has wide aristiforms, smaller skull with
+less pronounced ridges, and never has more than three counterfolds in
+the upper molariform teeth; _riparum_ closely resembles _hyleae_;
+_boimensis_ has thin aristiforms, small skull and no more than three
+counterfolds in the upper molariform teeth in contrast to _hyleae_,
+already discussed; _leucomystax_ closely resembles _boimensis_;
+_villicauda_ closely resembles both _hyleae_ and _riparum_; _mincae_ is
+similar to _hyleae-riparum-villicauda_; _canicollis_ has the number of
+counterfolds in all molars reduced to two; _gularis_ is large, has a
+strongly built and ridged skull, some upper molariform teeth with four
+counterfolds and wide aristiforms; _hendeei_ closely resembles
+_leucomystax_ and _boimensis_.
+
+The evidence obtained from study of specimens where two or more species
+occurred together was applied to the remaining samples and the
+geographic distribution was worked out. As a result the arrangement
+below was made, including all valid kinds already named and those here
+newly named from Brazil. The names of kinds I do not consider as
+belonging to the subgenus (and genus) are excluded. These are _Echimys
+macrourus_ Jentink, not seen, and _Proechimys cayennensis hoplomyoides_
+Tate (= genus _Hoplomys_). The application of names is tentative,
+however, because the types deposited in Europe have not been seen. An
+asterisk denotes the forms not seen by me.
+
+      _Proechimys guyannensis: arabupu, arescens, bolivianus, cherriei,
+      chrysaeolus, guairae, o'connelli, guyannensis*, hyleae, leioprimna,
+      mincae, nesiotes, ochraceus, oris, poliopus, ribeiroi, riparum,
+      trinitatis, urichi, vacillator*, villicauda, warreni._
+
+      _Proechimys longicaudatus: boimensis, brevicauda, elassopus,
+      hendeei, leucomystax, longicaudatus, nigrofulvus, pachita,
+      rattinus*, roberti, securus, simonsi._
+
+      _Proechimys semispinosus: amphichoricus, burrus, calidior,
+      centralis, chiriquinus, colombianus, decumanus, goldmani*,
+      gorgonae, gularis, hilda*, ignotus, kermiti, liminalis,
+      panamensis, rosa*, rubellus, semispinosus._
+
+      _Proechimys goeldii: goeldii, steerei._
+
+      _Proechimys canicollis._
+
+_Proechimys guyannensis_ appears to be more plastic than any other
+species. In size of animal, width of aristiforms, color and number of
+counterfolds in the cheekteeth, it shows marked response to variations
+in geographic conditions. _Proechimys longicaudatus_ is apparently less
+plastic; only the number of counterfolds shows marked variation.
+_Proechimys semispinosus_ varies much within its range. _Proechimys
+goeldii_ seems to be relatively uniform. _Proechimys canicollis_ shows
+relatively little variation throughout its range but probably is
+divisible into two or more subspecies.
+
+The primitive _Proechimys_ probably was large with a short tail, narrow
+aristiforms, strongly built skull, and five counterfolds in each
+molariform tooth. Primitiveness here is inferred from characters which
+now are of general occurrence in the whole group as opposed to those
+restricted in geographic occurrence.
+
+It is a curious fact that in this genus, populations from small islands
+are more primitive than populations on the mainland. Apparently a small
+population restricted to a small island tends to revert to the primitive
+type. The homozygous condition will tend toward a generalized genotype
+and the disappearance of secondary biotypes. _P. i. iheringi_ on the
+Island of São Sebastião averages larger, has thinner aristiforms, and a
+stronger skull than the same subspecies on the mainland, and the
+cheekteeth usually have two and three counterfolds. The same subspecies
+on the mainland has no more than two counterfolds. _Proechimys
+semispinosus gorgonae_ and _Proechimys semispinosus ignotus_, living on
+Gorgona and San José islands, respectively, are both characterized by
+large size, short tails, strong and conspicuously ridged skulls, and
+cheekteeth frequently with four and five counterfolds. On the mainland,
+closely related subspecies, like _P. s. panamensis_, _chiriquinus_ and
+_gularis_, far less frequently have four counterfolds in more than one
+or two teeth. More striking still is the population-sample of _gularis_
+from the island of Llunchi, in the Rio Napo, eastern Ecuador. In it
+there is a higher ratio of cheekteeth with four counterfolds than there
+is in the samples from the banks of the river.
+
+The two insular forms, _P. s. gorgonae_ and _P. s. ignotus_, referred to
+as primitive in the discussion above, have wide aristiforms, which is
+contrary to what would be expected in a primitive _Proechimys_.
+Supposing, however, as actually seems to be the fact, that narrowness of
+the aristiforms depends on an increased number of genes, we deduce that
+the population from the mainland, that gave rise to the populations of
+the islands, did not have all of the genes necessary to make the
+aristiforms narrow. In fact the subspecies known on the mainland, near
+the aforementioned islands, have wide aristiforms.
+
+Another point which favors the idea that narrow aristiforms result from
+an increased number of genes is that, generally, the aristiforms are
+narrow in any species whose geographic range is extensive and relatively
+uniform.
+
+_Proechimys goeldii_ is the species which has the largest number of
+characters that are judged to be primitive, and it may be the oldest
+stock. _P. semispinosus_, _P. longicaudatus_ and _P. guyannensis_ may
+have been derived from an early splitting of the genus or they may have
+branched off the main stem at different times. _P. canicollis_, however,
+seems clearly to be an offshoot of _P. guyannensis_; _canicollis_ shows
+greater resemblance to _guyannensis_ than to any other species. _P. g.
+vacillator_ is another close relative of _P. guyannensis_ with the
+number of counterfolds almost as much reduced as in _P. canicollis_.
+Conceivably, _vacillator_ is a full species, but the reduction in number
+of counterfolds in the teeth more probably expresses only one extreme of
+a gradient, as will be discussed below.
+
+
+SUBSPECIFIC VARIATION IN THE SUBGENUS PROECHIMYS
+
+In spite of the lack of specimens from areas in which _Proechimys_
+certainly occurs, it is evident that the genus has great plasticity and
+that the number of subspecies will be greatly increased as additional
+material is studied. Only perfunctory examination of samples from
+outside the area of Brazil shows me that there are several unnamed
+subspecies there. My impression is that Allen's _trinitatis_, of
+Trinidad, the genotype of _Proechimys_, will eventually be split.
+
+There are two main lines of subspeciation in _Proechimys guyannensis_.
+The one south of the Amazon River includes _P. g. bolivianus_, in
+Bolivia, _P. g. villicauda_, and _P. g. ribeiroi_ occurring on the
+divide of the headwaters of the Amazon and Parana rivers, in Brazil, and
+_P. g. hyleae_ in the lower Tapajoz and _P. g. nesiotes_ in the lower
+Tocantins. All six subspecies have a large number of counterfolds in the
+molariform teeth. In these six subspecies, p4 has four counterfolds and
+the lower molars have three each. Toward the northeastern coast the
+number of counterfolds decreases to three in p4 and to two in the lower
+molars, as in _P. g. arescens_, _P. g. leioprimna_ and _P. g. oris_.
+
+In northern South America, north of the Amazon River, the subspecies
+with the greatest number of counterfolds is _P. guyannensis warreni_
+(known from only the Demerara River area); p4 has four counterfolds and
+the lower molars have three each. The number decreases in all the
+adjacent populations: _P. g. guyannensis_, in the Guianas, _P. g.
+trinitatis_, and _P. g. urichi_ (going westward from the Guianas to
+Venezuela) have the counterfolds reduced to three in p4, but the lower
+molars still have the same number of counterfolds, namely, three,
+although there is a tendency for them to coalesce; farther west, on the
+coast, the number decreases to three counterfolds in p4 and to only two
+in the lower molars as in _P. g. guairae_ and _P. g. mincae_. Subspecies
+south of the coast show the same reduction of counterfolds, _P. g.
+cherriei_ and _P. g. o'connelli_ being examples; _P. g. ochraceus_ and
+_P. g. poliopus_ have the reduction carried to the upper molars, M3
+having usually only two counterfolds; _P. g. chrysaeolus_ in the valley
+between the Madalena and the Cauca rivers seems to be somewhat isolated
+and shows reversion to three counterfolds in the lower molariform teeth;
+directly southward of the range of _P. g. warreni_ the number of
+counterfolds decreases to three in all lower cheekteeth (population at
+Ayan-Tepuy, southern Venezuela), and then to three in p4 and to two in
+the lower molars, as in _P. g. arabupu_ on the Brazilian side of Mount
+Roraima, and the reduction is extended to the upper molars in _P. g.
+vacillator_.
+
+On the north bank of the Amazon, the only population of _P. g. hyleae_
+known to me (from Obidos) has four counterfolds in p4 and three in the
+lower molars; _P. g. riparum_, from Manaus, also on the north bank of
+the Amazon, has three counterfolds in p4 and two counterfolds in the
+lower molars. _P. g. hyleae_ occurs also on the south bank of the
+Amazon. _P. g. riparum_, therefore, may be the northern part of the
+southern cline, instead of the southern end of the northern cline.
+
+The whole picture, as outlined above, may be explained by assuming that
+the species _P. guyannensis_ differentiated somewhere on the Central
+Plateau of South America, with three counterfolds in each upper
+molariform tooth, four counterfolds in the lower premolar and three
+counterfolds in the lower molars. The species might have extended its
+range to the Guianas and then all the biotypes with reduced number of
+counterfolds might have slowly developed by natural selection. The
+gradient is, broadly, from subspecies with greater number of
+counterfolds in more humid areas, to a gradually lessening number of
+counterfolds in less humid areas.
+
+_Proechimys longicaudatus_ is limited in the south to the headwaters of
+the Parana River drainage, where the subspecies _P. l. roberti_ and _P.
+l. longicaudatus_ are found. The species ranges northward through the
+Tapajoz drainage, with _P. l. leucomystax_ in the headwaters and _P. l.
+boimensis_ in the lower course. To the northwest and west the species is
+represented in Bolivia by _P. l. securus_; _P. l. elassopus_, _P. l.
+simonsi_, _P. l. pachita_, and _P. l. hendeei_ occur in Peru and _P. l.
+brevicauda_ in Peru and Brazil; and _P. l. nigrofulvus_ occurs in
+Ecuador. Again in _P. longicaudatus_ it seems that the number of
+counterfolds follows a gradient from more humid areas with four
+counterfolds in p4, as seen in _nigrofulvus_, _pachita_, _simonsi_,
+_elassopus_ and _brevicauda_, decreasing to three or four in _securus_,
+to three in _longicaudatus_, but with m3 having only two counterfolds in
+_leucomystax_ and _roberti_. _P. l. boimensis_, widely separated in the
+lower Tapajoz (no samples being known from the intervening range) may be
+the end of a cline started by _leucomystax_ with only 2 counterfolds in
+m3 and ending to the northward with four counterfolds in m3. Over the
+same area the counterfolds in p4 increase from 3 to 4.
+
+Of _Proechimys goeldii_ I have had inadequate material but there seems
+to be a similar gradient in it which may be traced from _P. g. steerei_
+to _P. g. goeldii_. _P. g. steerei_ has four counterfolds in more upper
+molars than occurs in the other subspecies.
+
+_Proechimys semispinosus_ has its wide range in the mountainous, western
+area of South America, the headwaters of the Amazon drainage and
+northward in Central America and the nearby Pacific Islands. In these
+populations a gradient may exist in the number of counterfolds which is
+varied in every population. The highest number seems to occur in the
+populations from northern Peru and Ecuador, decreasing from there in all
+directions, except in the Panamanian and Columbian islands. In gross
+examination, it seems that the size of the animals increases to the
+northwards.
+
+
+SPECIFIC VARIATION IN THE SUBGENUS TRINOMYS
+
+Some specific characters are duplicated in each of the two subgenera;
+that is to say, there are some parallel developments and they give the
+common generic stock its biotypical variability. Among these parallel
+developments are the width of the aristiforms, the amount of pigment in
+the agouti-colored setiforms, and the shape of the nasal bones. Other
+characters, however, appear in one subgeneric group and not in the
+other. The specific variation will be discussed separately for each
+subgenus.
+
+The aristiforms are narrow and soft in _P. dimidiatus_ and in the other
+species are wide and stiff, and on the outer thighs and rump some are
+light-colored. _P. albispinus_ has the maximum number of light-colored
+aristiforms; they are present over the sides and back. This species has,
+however, a type of aristiforms unique in the genus--the clavate type.
+The tail is longer in _P. iheringi_ and _P. setosus_ than in _P.
+dimidiatus_ and _P. albispinus_; the longer type is associated with a
+penicillate tip suggesting an adaptation to arboreal habit. The skull
+and nasals are longer in _P. dimidiatus_ and _P. iheringi_ than in _P.
+setosus_ and _P. albispinus_. In the latter two species the longitudinal
+dorsal outline of the skull is conspicuously convex as opposed to
+slightly convex in the other two species. The palate is longest in _P.
+dimidiatus_ and _P. iheringi_ extending posteriorly to the level of the
+second molars; it is slightly shorter in _P. setosus_ and shortest in
+_P. albispinus_ where it does not extend behind the level of the first
+molars. The incisors are opisthodont in _P. dimidiatus_ and _P.
+iheringi_ and orthodont in _P. setosus_ and _P. albispinus_ and even
+proodont in one part of the last species.
+
+The molariform teeth have a large number of counterfolds in both _P.
+dimidiatus_ and _P. iheringi_, although the number varies but little in
+the first species and much in the second. The variation in _P. iheringi_
+decreases in populations of increasingly more northern geographic
+distribution; in both _P. setosus_ and _P. albispinus_ the number of
+counterfolds is greatly reduced; there is only one in most specimens of
+_P. albispinus_. The incisive foramen is small and nearly round in _P.
+dimidiatus_, larger and elongate in _P. iheringi_, very narrow and
+fissurelike in both _P. setosus_ and _P. albispinus_.
+
+The characters of _Trinomys_, as briefly outlined above, seem to be the
+result of one original species having split first into four species
+which provide a gradient for certain characters. Subsequently one of
+these four species, _P. iheringi_, split into six subspecies and
+another gradient, parallel to the first, and involving the same
+characters, is to be seen.
+
+The interrelationship among the species is evident, not only because
+they have the same subgeneric characters, but because the full species
+themselves provide successive steps in a stairway of increasing
+specialization from _P. dimidiatus_ to _P. albispinus_.
+
+Morphologically _P. dimidiatus_ and _P. iheringi_ are sometimes
+difficult to distinguish, especially on the basis of cranial features.
+Nevertheless close attention to the small, nearly round, incisive
+foramen of _P. dimidiatus_ versus the larger, more elongate foramen in
+_P. iheringi_ will permit separation of the two. However, the two
+species live in the same place and one is led to infer that there may be
+greater differences in their physiology than in their morphology. In
+fact Dr. H. W. Laemmert, from the Serviço de Estudos e Pesquisas Sobre a
+Febre Amarela in Brazil, informs me that while _P. dimidiatus_ was
+highly susceptible to the virus of yellow fever (18 out of 24 with virus
+in circulation), _P. iheringi_ showed a lower rate of susceptibility (3
+out of 25 with virus in circulation). _P. longicaudatus roberti_,
+belonging in the other subgenus, showed no susceptibility at all.
+
+At Teresópolis, Estado do Rio de Janeiro, the two species were found in
+two different forests, only a few kilometers apart, but _dimidiatus_
+lived at a higher elevation, where the humidity was remarkably higher.
+Naturally the plant associations were different in the two forests. This
+seeming ecological adaptation of the two kinds of _Proechimys_ may
+explain why _P. iheringi_ ranges farther north; the forests to the
+northward are less humid.
+
+One of the four species, _P. setosus_, subspecies _elegans_, was used by
+Winge (1941:80, 82) as representative of the genus _Proechimys_ when he
+was estimating the relationships of that genus. Because _Cercomys_, with
+four crests in each of its cheekteeth, was, on other grounds, regarded
+by him (_op. cit._: 80) as "... the most primitive genus within the
+group.", and because he noted in _P. s. elegans_ 4 crests in P4 and in
+some first molars, he concluded that _Proechimys_ was "very closely
+related to _Cercomys_." His conclusion seems to be correct, but actually
+other species of _Proechimys_ (subgenus _Trinomys_), for example, _P.
+dimidiatus_, have four or more crests in each cheektooth, and,
+therefore, may be considered as more closely related to _Cercomys_ than
+is _P. setosus_. If a large number of crests indicates primitiveness,
+_P. dimidiatus_, always with four, is more primitive than any other
+species in the subgenus _Trinomys_. Also, the large skull, long hind
+foot, short tail and thin aristiforms of _P. dimidiatus_, in my opinion,
+are primitive characters.
+
+
+SUBSPECIFIC VARIATION IN THE SUBGENUS TRINOMYS
+
+One of the species of _Trinomys_, _Proechimys iheringi_, is here
+subdivided into six subspecies which show a clinal variation. _P. i.
+iheringi_, in the southernmost part of the range of the species (Ilha de
+São Sebastião), has three counterfolds in the upper cheekteeth of almost
+every young specimen but one of these counterfolds, since it is small,
+very shallow, and disappears after little wear, is probably in the
+process of disappearance; all lower cheekteeth have two counterfolds or,
+rarely, m3 has only one. _P. i. bonafidei_ is the next subspecies
+northward, where it was collected at 850 m altitude (Fazenda Bõa Fé).
+This subspecies still has two counterfolds in all the upper cheekteeth;
+only 3 out of 16 specimens fail to have these counterfolds coalesced in
+one or more of the teeth. In the lower cheekteeth the coalescence is
+evident in 18 per cent of the specimens. _P. i. gratiosus_, from
+Floresta da Caixa Dagua (alt. 750 m), geographically is well removed from
+_bonafidei_ (more than two degrees north), and no samples were obtained
+from the intervening area. It shows such great reduction in the
+counterfolds that the existence of intermediate populations is clearly
+suggested. Every upper cheektooth of this subspecies has the two
+counterfolds coalesced and in 40 per cent of the specimens M3 has only
+one counterfold; in the lower cheekteeth 60 per cent of the specimens
+have only one counterfold in m3. _P. i. panema_, occurring approximately
+100 kilometers to the northward of _P. i. gratiosus_ (lowland form), has
+one counterfold in M3 in only 20 per cent of the specimens but the lower
+third molar has only one counterfold in 80 per cent of the specimens. In
+_P. i. denigratus_, from about 3 degrees north of the range of _P. i.
+panema_, the reduction is proportionately greater: P4 now is the only
+upper cheektooth with two counterfolds in every specimen; all molars
+tend to have only one; p4 has also two counterfolds but all lower molars
+have only one.
+
+The relative size of the tail also varies in a cline from south to
+north. Its length is approximately 87 per cent of the length of the head
+and body in _P. iheringi_; 88 per cent in _bonafidei_; 99 per cent in
+_gratiosus_; 100 per cent in _panema_; and 103 in _denigratus_.
+
+One of the subspecies, _P. i. paratus_, however, seems to be completely
+out of the dental cline. It was collected in the near proximity of the
+type locality of _P. i. gratiosus_, at an elevation of 120 m lower. This
+subspecies has two counterfolds in all molariform teeth and only one of
+the two specimens known shows these counterfolds coalesced in P4 and M1.
+The sample, 2 specimens, is too small to be trustworthy; hence it is
+impossible satisfactorily to account for the break in the clinal
+variation. Conceivably two full species are involved, but I prefer at
+present to defer decision on this problem until such time as more
+evidence is accumulated.
+
+_P. setosus_ is poorly represented, both of the available skins being
+faded. Furthermore, no type locality is known for the subspecies _P. s.
+setosus_.
+
+_P. albispinus_ has only two known subspecies: _P. a. albispinus_,
+living in a region of higher humidity, is slightly the darker and has
+subapical zones of the setiforms on the sides Ochraceous-Tawny; _P. a.
+sertonius_, living in a much drier region, has the same subapical zone
+Ochraceous-Buff. The number of specimens of _P. a. sertonius_ is so few
+that no gradient can be detected, even if one exists.
+
+
+
+
+TAXONOMIC CHARACTERS
+
+
+Size and Proportions of External Parts
+
+Absolute size of head and body, tail, hind-foot and ear are useful in
+distinguishing subgenera and subspecies and to some extent in
+differentiating species.
+
+The length of head and body is large to medium in _Proechimys_ and
+medium to small in _Trinomys_. The tail is long to medium in _Trinomys_
+and short in _Proechimys_. The longest tail, 242 mm, is found in _P. i.
+denigratus_, and the shortest tail, 123 mm, in _P. g. steerei_. The
+relative length of tail also provides gradients or clines.
+
+In every species, males surpass females in average size. Nevertheless,
+the largest animals are usually females. How this paradoxal fact is to
+be accounted for, I am not sure, but it may be that the animals grow as
+long as they live and that females have more chances to survive longer
+since the care of the young keeps them closer to shelter.
+
+_Color._--Upper parts vary from Buckthorn Brown to Ochraceous-Buff. Dark
+color ordinarily is correlated with an environment of higher degree of
+humidity and light color with lower humidity. However, species may be
+found in similar conditions of humidity but differing in color.
+_Proechimys albispinus albispinus_, for example, a light-colored form,
+is found in areas where the rainfall averages 1,000 to 1,500 mm of
+annual precipitation, in the isohygra of 80 per cent relative humidity.
+These conditions actually are similar to those where _P. dimidiatus_, of
+darker color, is found. The subspecies _albispinus_, however, ranges
+mostly over a dry area and the fact that it occurs also in a moist area
+without appreciable change in color is difficult to explain.
+
+Insular populations are usually darker or richer in color than
+corresponding continental populations. On a small island, uniformity of
+environment and inbreeding may be responsible for an accumulation of
+characters for richness of color.
+
+
+Pelage
+
+The pelage provides most useful taxonomic characters. Excepting the
+vibrissiform hairs, all of the elements of the pelage have a common
+feature, the flattened shape. The hair constellation (_cf._ Toldt, 1935)
+on the upper and lateral surfaces is composed of hairs of two main
+types: _aristiforms_ (guard hairs) and _setiforms_ (over hairs).
+
+The aristiforms are wide, strong, and have the dorsal (= anterior)
+margins raised, forming a wide shallow longitudinal groove on the dorsal
+face of the hair. The tip is a filament that usually is lacking in
+aristiforms which are especially strong. Wear probably removes these
+tips. The aristiforms have the bases whitish or grayish and the amount
+of pigment gradually increases distally to a dark brown or blackish
+shade. On the dorsal and lateral surfaces of the head the aristiforms
+are small and narrow but gradually increase in length and width caudad
+on the animal. The maximum development is reached in the middorsal
+region, from where they decrease in size and number toward the lateral
+surfaces or caudad. This decrease in the development of the aristiforms,
+however, is not uniformly gradual. Generally, the aristiforms become
+increasingly conspicuous in a middorsal band, but they extend to the
+sides and onto the outer sides of the thighs; the band narrows rapidly
+on the rump. In the subgenus _Trinomys_, where the aristiforms attain
+their maximum development, they are still strong and conspicuous on the
+rump and sometimes around the base of the tail. In _Proechimys_ the
+aristiforms do not extend caudad from the hips. Also, in _Trinomys_,
+besides the ordinary lanceolate type, there are some aristiforms on the
+dorsal surface with a clavate shape; the base is wide and the distal
+part narrow. This parallels the conditions in the pelage of the most
+spiny species in the genus _Echimys_, _Echimys chrysurus_
+(Lichtenstein).
+
+The recently named subspecies _Proechimys cayennensis hoplomyoides_
+Tate, 1939, shows an extraordinary development of the aristiforms on
+the back and sides such as occurs in the genus _Hoplomys_. Actually the
+small bulla, wide basisphenoid and tooth structure add to the
+possibility of _hoplomyoides_ being a true _Hoplomys_, and worn teeth
+might have been responsible for the difficulty which Tate had in
+allocating the form to the proper genus. However, the narrow braincase
+is more nearly like that of _Proechimys_ than that of _Hoplomys_. The
+intermediate nature of _hoplomyoides_ argues for including the genus
+_Hoplomys_ as a subgenus of _Proechimys_.
+
+Species with narrow aristiforms have a rather soft and flexible pelage,
+while those with wide aristiforms have harsh, spiny pelage. The
+aristiforms vary in width from 0.45 to 1.3 mm, depending upon the
+species or subspecies.
+
+Animals with narrow aristiforms tend to have a more or less uniform
+coloration throughout the dorsal parts. The blackish distal parts of the
+aristiforms regularly interline the ground color made by the subapical
+zone of the setiforms. If, on the contrary, wide aristiforms occur, the
+dorsal surface is conspicuously marked by the wide blackish lines among
+spots of color formed by the subapical zones of the setiforms. No clinal
+variation was detected in width of aristiforms but geographic variation
+in width was noted; for example, the subspecies of _P. iheringi_ differ
+in this respect.
+
+The setiforms are narrow and flattened but are without pronouncedly
+raised margins. The setiforms are usually bicolored on the dorsal and
+lateral surfaces of the animals, with a subapical zone of some
+reddish-brown color, like Ochraceous-Orange or Ochraceous-Buff. They are
+whitish or gray on the basal parts and gradually blacken toward the tip,
+but have a reddish subapical zone. Common exceptions to this pattern are
+setiforms without subapical zones; these appear on the dorsal surface
+among setiforms which are normal in possessing distinctive subapical
+zones. Also there are setiforms without blackened tips on the lateral
+surfaces. Due to their relative abundance and subapical color, these
+setiforms are responsible for the dominant color on the upper parts.
+Like the aristiforms, they are longer and wider in the middorsal region
+of the animal and are gradually less developed on the remainder of the
+upper parts. Actually there is more than one type of setiform in the
+hair constellation; they vary in length, width and color. Attention was
+not given, however, to every type of setiform.
+
+The ventral surface of the body and the inner sides of the legs are
+uniformly covered by short setiforms, thinner and more sparsely
+distributed on the inner side of the legs. These setiforms are usually
+uniformly white in color or, sometimes, the distal parts are buff or
+more richly colored.
+
+Vibrissiforms are scattered on the dorsal and lateral surfaces of the
+body, and in penicillate arrangements on the head. They are longer than
+the pelage proper, have a nearly circular cross-section and are blackish
+in color.
+
+
+Skull
+
+The absolute size of the skull is proportionate to bulk of the body. The
+supraorbital and parietal ridges are especially developed in the _P.
+semispinosus_ group, where they extend across the parietals to the
+interparietals. In all members of the subgenus _Proechimys_, these
+ridges extend onto the parietal region. In _Trinomys_, however, they do
+not extend so far posteriorly as the parietal, but only onto the
+squamosal.
+
+The rostrum varies from slender to stout. Elongate rostra are common in
+_Proechimys_; _Trinomys_ has a short blunt rostrum.
+
+The infraorbital foramen commonly has a ventral groove for nerve
+transmission in many forms of _Proechimys_ but _Trinomys_ almost always
+lacks this groove. Presence or absence of the groove is a subspecific
+character in the subgenus _Proechimys_.
+
+The jugals are dorso-ventrally wide in _Trinomys_ except in the species
+_P. setosus_. In _Proechimys_ a dorso-ventrally narrow jugal is the
+rule, but _P. canicollis_ has an especially wide jugal. A postorbital
+process appears on the jugo-squamosal suture and is here called
+postorbital process of the zygoma. In _Proechimys_ it is more or less
+weakly developed and shows no variation of systematic worth. In
+_Trinomys_, on the other hand, this process varies in a clinal way (_P.
+iheringi_) and stages of the gradient characterize populations of
+subspecific rank.
+
+Linear and spatulate shape of the humular process of the
+pterygoid constituted specific characters for Thomas, but there is so
+much individual variation in the shape of this process in almost every
+population that it has not been used in the present account.
+
+The mesopterygoid (interpterygoid) fossa in almost every specimen
+extends anteriorly to the level of M1 or M2 in _Trinomys_, and to M3 in
+_Proechimys_. Exceptions may occur, as in _P. hendeei_, where the fossa
+extends to the level of M2.
+
+
+Incisive Foramen
+
+The shape and dimensions of the incisive foramen long have been
+recognized as providing specific characters. Large size of the foramen
+is probably correlated with the requirement for a large amount of
+moisture reaching Jacobson's organ in the nasopalatine space; the
+moistening of the sensory epithelium is certainly involved. There seems
+to be a certain correlation between small size of the incisive foramen
+and high degree of humidity in the environment. Shapes and dimensions of
+the foramen appear as simple or multiple biotypes and provide characters
+which can be employed to differentiate subspecies, species and even
+subgenera. Usually a character, say a general shape, occurs in nearly
+all populations of a given subspecies but the particular shape seems to
+be more closely correlated with ecological conditions, especially
+humidity. Animals which live far away from large rivers usually have
+larger foramina than animals which live close to rivers.
+
+Both the premaxilla and the maxilla develop processes which form a
+sheath for the vomer. This vomerine sheath forms a bridge which
+longitudinally crosses the incisive foramen; the structure of this
+bridge varies widely. Sometimes the maxillary part is not developed and
+the sheath is incomplete posteriorly; sometimes this maxillary part is
+very slender and merely touches the premaxillary part. The premaxillary
+part, however, is always well developed.
+
+
+Teeth
+
+Considered by itself the variation in the tooth pattern can lead to
+erroneous conclusions as to differentiation of species, because the
+number of folds on the occlusal face of a tooth and the depth of certain
+folds may be subject to great individual variation as shown by
+examination of more than one large series of specimens of the same kind,
+age and sex from a single locality. Also there are geographic gradients
+or clines, in number of folds. Nevertheless the variation in number of
+folds, when measured at sufficient intervals along a cline, may provide
+quantitative characters useful in differentiating subspecies.
+
+[Illustration: FIGS. 2-17. Second left upper molar of the two subgenera
+_Proechimys_ and _Trinomys_. All × 8. Anterior border of tooth is at the
+top of each figure (Nos. 9 and 17 excepted). Note especially that main
+fold is short in _Proechimys_ and long in _Trinomys_.
+
+    FIGS. 2-9. _Proechimys_ (_Proechimys_) _semispinosus liminalis_,
+    female, MN no. 6243, Rio Quichito. Fig. 2, unworn crown. Figs. 3-8,
+    cross sections at 0.5 mm. intervals, showing changes in the main fold
+    and counterfolds at increasing depths as the tooth was ground down.
+    Fig. 8 is 3 mm. below surface shown in fig. 2. Fig. 9, posterior view
+    with proximal end of the tooth open showing basal ends of folds.
+    Later in life the proximal end closes and three roots are formed.
+
+    FIGS. 10-17. _Proechimys_ (_Trinomys_) _iheringi denigratus_, female,
+    SEPFA no. 17060, Mata do Ribeirão da Fortuna. Figs. 10-16
+    corresponding to figs. 2-8. Fig. 17, posterioventral view with
+    proximal end of the tooth open and part of walls cut away, showing
+    basal ends of folds. Later in life, as in _Proechimys_, the proximal
+    end closes and three roots are formed. ]
+
+The main fold involves both the occlusal face of the tooth and the side
+wall. The counterfolds, which are smaller counterparts of the main fold,
+in most instances also implicate the wall of the tooth opposite to that
+marked by the main fold, but are to be seen mostly on only the occlusal
+face of the tooth. Unerupted teeth with the crowns unworn and other
+teeth which had barely broken through the gums were ground down to
+permit the making of drawings of the surfaces at different levels. This
+study revealed that the main fold is deepest in the wall of the tooth.
+The development of the main fold varies in two different ways: in all
+samples from southeastern and eastern Brazil it is strongly developed,
+deeply grooves the tooth through its crown and, in younger individuals,
+completely divides the occlusal surface of the tooth. As use wears down
+the crown, the main fold soon becomes separated from the opposite wall
+and then gradually shortens toward its basal portion. In the other type,
+common to animals of all the remaining part of the range of the genus,
+the main fold is rather short, never reaching the opposite wall. In this
+case, however, one of the counterfolds usually appears almost opposite
+the main fold in such a way that in non-erupted or just-erupted teeth
+the main fold and one counterfold may be connected by a shallow groove
+that may give the impression of extension of the main fold and,
+therefore, lead to false interpretations. Closer examination shows that
+the counterfold which apparently meets the main fold is really situated
+anteriorly or posteriorly to it, in upper or lower teeth respectively.
+One subspecies in the subgenus _Trinomys_ differs from the general
+characteristics of the subgenus in sometimes showing a small main fold
+in P4 whereas it is large in all other cheekteeth. The structural
+differences here mentioned in the main fold were never before
+recognized. Therefore, the meaning of "quadrilaminate" pattern, "three
+outer folds" or "three inner folds" (of authors) is not consistent
+insofar as the two groups are concerned.
+
+Writers have more or less tacitly admitted three as the usual number of
+counterfolds present in the upper molariform teeth. Ellerman, for
+example (1940:117), states: "Upper cheekteeth normally with three outer
+and one inner folds each, these soon becoming isolated as islands. A few
+species, which will be discussed below, vary slightly in pattern."
+Thomas (1921:140) erected the subgenus _Trinomys_ on the basis of the
+upper molariform teeth having only three laminae. Actually a meticulous
+study of widely varying samples shows that the number of counterfolds
+may vary from _one_ to _five_, the usual number being three or four. One
+of the most important facts to record on this subject is that young
+specimens with slightly worn molariform teeth are more apt than either
+adult or younger specimens to show the maximum number of counterfolds.
+Usually nonworn teeth show rounded crests and valleys of different
+depth. For example, it is common to see one continuous groove giving the
+impression of a main fold crossing the occlusal surface transversely.
+The slightest wear of the occlusal surface, however, shows that really
+there are two valleys instead of one. The two are the main fold and one
+counterfold. In this case, it would be easy to confuse the two types of
+teeth, one with the main fold short and the other with the main fold
+extending almost all the way across the occlusal surface.
+
+Some of the counterfolds are especially shallow and tend to disappear in
+an early stage of wear, and adult individuals may have these folds
+completely worn away. Advanced wear usually develops a cuplike occlusal
+surface with only the remains of the main fold and also remains of one
+or more counterfolds represented by small enamel islands (Figs. 2 to
+17). In the form _Proechimys iheringi iheringi_, for example, every
+tooth shows three counterfolds in the upper molariform teeth of
+individuals in which the wear is not advanced. This number, however, is
+less in all or part of the molariform teeth of older individuals.
+
+Adjacent counterfolds may appear to be coalesced in many instances.
+Coalescence is more likely to be seen in species where a wider variation
+in the number of the counterfolds is involved and it appears as a
+gradient in the reduction of the number of counterfolds.
+
+Of great importance, as a general feature of molariform teeth, is the
+relative size as related to the geographical distribution, showing,
+again, a natural division in the genus. In all forms of southeastern
+Brazil the premolars are larger than the first molars, the first molars
+are larger than the second molars, and the second molars are larger than
+the third molars. The forms from central and northern Bahia, Brazil,
+have the molariform teeth more or less the same size. The forms from the
+remaining part of the area occupied by the genus have premolars smaller
+than the first molars, the first molars smaller than the second molars,
+but the second molars larger than third ones.
+
+
+
+
+HABITS
+
+
+_P. dimidiatus_ was studied in the field and laboratory. _P. dimidiatus_
+in captivity showed regular diurnal activity, coming out of the nest for
+food at intervals. Individuals were fed a cereal mixture and nuts of
+small size. The animals usually buried the nuts in the sand of the outer
+cage. While holding the nut with the mouth and front feet, the animal
+patted the sand rapidly, thus burying the nut, and it then pushed more
+sand over the place with the front feet.
+
+Sometimes the emergence from the nest is followed by a long yawning and
+stretching ceremony. The animal spreads the fore and hind legs widely
+apart, while the back is curved down and the head and tail turn upward.
+Then one of the hind legs is stretched backward and, at the same time,
+the mouth is opened widely and the tail is moved in an undulatory
+fashion. The operation may be repeated using the other legs, or not.
+
+_P. dimidiatus_ was regularly found in climax forest. The best shelter
+and nesting ground was usually under boulders, commonly not farther than
+10 meters from water. The entrance to the nest was kept clean. No more
+than two adult animals (male and female) were captured in the same
+shelter, and only a few times were young captured in the same place with
+adults. Nesting places were located also at the bases of trees and near
+fallen logs where litter accumulates.
+
+Records of animals kept in captivity show that the species _dimidiatus_
+survives more than two years. Specimen MN no. 5448 [M] was adult when
+captured by the Serviços de Estudos e Pesquisas sobre a Febre Amarela on
+December 5, 1938, and died on January 17, 1942. Therefore, it lived for
+more than 1,139 days.
+
+_Proechimys dimidiatus_, in Rio de Janeiro, as well as _P. i. bonafidei_
+and _P. i. iheringi_ which live in the same region, were found breeding
+from September to November and from March to May. _Proechimys
+longicaudatus roberti_, in Anapolis, Goiaz, was found breeding from July
+to November and from January to March. _P. g. hyleae_ and _P. g.
+leioprimna_ in the lower Tapajoz and lower Tocantins rivers, Pará, were
+found breeding in January.
+
+It seems that in the Central Plateau and southeastern Brazil,
+_Proechimys_ has two litters per year, one in the early spring and a
+second in the late summer. The number of young per litter varies from 1
+to 5, although 2 is the usual number.
+
+
+
+
+CHANGES WITH AGE
+
+
+_Juveniles._--The animals are born with a thick pelage of thin
+aristiforms and thin setiforms. The color is uniformly blackish brown.
+The nose, hands, feet, ears and tail are pinkish; P4 and M1 are already
+erupted and the second molars are included in the bony alveoli. The
+incisors are orthodont; the rostrum is short and the braincase is wide.
+The posterior part of the skull is greatly curved dorsally. No change is
+noticed in the pelage before the second molars erupt and become
+functional.
+
+_Adolescents._--As soon as the second molars become functional, the
+pelage starts molting on the back. The thin aristiforms are still in
+place but the aristiforms of the adult pelage may be noticed growing
+under them in an oval patch which extends from behind the shoulders
+caudad to the hips. At that age the first, agouti-colored aristiforms
+appear on the mystacial region, immediately behind the vibrissiforms.
+The rostrum gradually lengthens and the braincase appears to become less
+inflated.
+
+By the time the third molars erupt, the aristiforms start showing among
+the setiforms which are now changing to agouti color in the same area on
+the back, while the thin aristiforms of the juvenal stage disappear. The
+agouti setiforms are appearing also posteriorly from the mystacial
+region to the sides of the head and neck and, at the same time, on the
+frontal region. The patch of glossy aristiforms and setiforms on the
+back is sharply differentiated from the dull juvenal pelage of the sides
+and rump. In a later stage the area of agouti setiforms on the sides of
+the neck extends to the outer sides of the arms and finally reaches the
+area on the back where the agouti setiforms were already developed.
+
+_Adults._--When the third molars become functional, the agouti setiforms
+are in place except for those on the upper sides of the neck. The
+aristiforms have now extended over their normal area of distribution. As
+soon as the third molars show wear, the premolars and first molars have
+the counterfolds isolated in the occlusal surfaces as enamel islands.
+Wearing gradually isolates all counterfolds.
+
+_Senile_ individuals.--Progression of wear soon eliminates the signs of
+the shallowest counterfolds from the occlusal surface and finally the
+tooth is reduced to a short crown with a cuplike occlusal surface
+completely filled with dentine. Only the main fold usually remains; it
+is more or less reduced in size.
+
+From the records of the Serviços de Estudos e Pesquisas sobre a Febre
+Amarela, the following data for males of _Proechimys longicaudatus
+roberti_ were obtained:
+
+  ======================+=========+==========+========+=========+=======
+                        | Number  |          | Length |         | Length
+              AGE       |   of    |  Weight  | of head|  Length |   of
+                        | cheek-  | in grams |  and   | of tail |  hind
+                        | teeth   |          |  body  |         |  foot
+  ----------------------+---------+----------+--------+---------+-------
+  One day old           |    2    |    20.5  |    70  |     53  |   24
+  17 days old           |    2    |    26.0  |   110  |     60  |   28
+  Juvenile              |    2    |    85.0  |   150  |    105  |   39
+  Adolescent            |    3    |   115.0  |   175  |    120  |   45
+  Adolescent (older)    |    3    |   180.0  |   195  |    135  |   45
+  Adult                 |    4    |   200.0  |   223  |    158  |   48
+  Senile individual     |    4    |   360.0  |   230  |    170  |   48
+  ----------------------+---------+----------+--------+---------+-------
+
+The weights and measurements (except for one- and 17-day-old animals)
+represent averages of specimens of the different ages.
+
+
+Genus =Proechimys= J. A. Allen
+
+_Genotype._--_Echimys trinitatis_ Allen and Chapman, by original
+designation.
+
+      _Proechimys_ Allen and Chapman, 26 December 1899, Bull. Amer. Mus.
+      Nat. Hist., 12(20):264, orig. description; Tate, 1935, Bull. Amer.
+      Mus. Nat. Hist., 68(5):398; Ellerman, 1940, The families and genera
+      of living rodents, Brit. Mus. (Nat. Hist.), 1:115.
+
+      _General characters._--Muriform echimyids of medium size; pelage
+      with flattened and lanceolate and sometimes clavate aristiforms,
+      varying greatly in width and distributed over most of the dorsal
+      surface from shoulders to hips or base of tail; setiforms also
+      flattened, evenly distributed throughout; entire ventral surface
+      and inner sides of legs white or, rarely, invaded by some buffy
+      color; tail shorter than, equal to, or slightly longer than, head
+      and body, bicolored and with a few bristles between scales,
+      sometimes heavily penicillated; feet long and narrow; pollex
+      rudimentary; hallux shorter than fifth toe; ears wide and long;
+      mammae 2-1=6.
+
+      _Skull._--Generally elongate and strongly built, with supraorbital
+      ridges well developed, frequently extending across parietals
+      toward occipital region; zygomatic arches variable in depth,
+      always with postorbital process; infraorbital foramen with or
+      without lower groove for transmission of nerve; incisive foramen
+      usually large; vomerine sheath complete or incomplete;
+      mesopterygoid fossa extending forward at least to plane of third
+      molars; bullae large; angular process of mandible turned upward.
+
+[Illustration: FIGS. 18-21. Occlusal views of the upper left and lower
+right molariform teeth of the two subgenera of the genus _Proechimys_.
+Anterior end of the tooth row at the top of drawing. All × 6.
+
+    FIGS. 18-19. _Proechimys_ (_Proechimys_) _goeldii steerei_, sex ?,
+    USNM no. 105537, "Hyutanaham." Upper teeth at left (fig. 18).
+
+    FIGS. 20-21. _Proechimys_ (_Trinomys_) _dimidiatus_, male, MN no.
+    6256, Pedra Branca. ]
+
+     _Teeth._--Incisors opisthodont, orthodont or proodont, not grooved;
+     upper molariform teeth with a main internal fold and one to five
+     external counterfolds which usually appear as enamel islands in
+     worn teeth, these counterfolds barely implicating the lateral wall;
+     lower molariform teeth with folds as in the upper molariform teeth
+     except that they are reversed and the number of internal
+     counterfolds is usually fewer in the molars.
+
+
+
+
+ARTIFICIAL KEY TO THE SUBGENERA AND SPECIES
+
+
+  1. (_a_) Tail less than 90 per cent of head and body; aristiforms
+         not evident on outer thighs and rump; skull
+         with ridges across parietals; size of upper cheekteeth
+         increasing from P4 to M2; main fold small.
+                                          subgenus PROECHIMYS,         2
+
+     (_b_) Tail 90 per cent or more of head and body; aristiforms
+         evident on outer thighs and rump; skull with
+         no ridges across parietals; size of upper cheekteeth
+         decreasing from P4 to M3; main fold large.
+                                          subgenus TRINOMYS,           5
+
+  2. (_a_) One or more upper molars with four counterfolds             3
+     (_b_) Upper molars with no more than three counterfolds,          4
+
+  3. (_a_) Aristiforms wide (more than 0.7 mm).  _P. semispinosus_, p. 342
+     (_b_) Aristiforms narrow (less than 0.7 mm) _P. goeldii_,      p. 338
+
+  4. (_a_) Aristiforms wide (0.9 mm or more), or narrow (0.6
+         to 0.7 mm) but then with only two counterfolds in
+         each lower molar                      _P. guyannensis_,    p. 355
+     (_b_) Aristiforms narrow (0.5 to 0.65 mm) but with one or
+         more lower molars having three counterfolds.
+                                               _P. longicaudatus_,  p. 346
+
+  5. (_a_) Aristiforms narrow (0.5 mm) and limber; no differentiated
+         light-colored aristiforms on outer thighs and
+         rump; incisive foramen short and widest posteriorly
+                                               _P. dimidiatus_,     p. 371
+     (_b_) Aristiforms 0.6 mm or more and stiff; differentiated
+         light-colored aristiforms on outer thighs and rump;
+         incisive foramen elongated and constricted posteriorly        6
+
+  6. (_a_) Skull large, more than 50 mm in total length, incisors
+         opisthodont                           _P. iheringi_,       p. 373
+     (_b_) Skull small, less than 49 mm in total length, incisors
+         orthodont or proodont                                         7
+
+  7. (_a_) No clavate aristiforms, tail with white tip,
+                                               _P. setosus_,        p. 384
+     (_b_) Clavate aristiforms among the ordinary ones, tail
+         without white tip                     _P. albispinus_,     p. 388
+
+[Illustration: FIG. 22. Map showing the distribution of the two
+subgenera of the genus _Proechimys_.]
+
+[Illustration: FIG. 23. Map showing the geographic ranges of four
+species of the genus _Proechimys_.]
+
+[Illustration: FIG. 24. Map showing the geographic ranges of four
+species of the genus _Proechimys_.]
+
+
+Subgenus =Proechimys= J. A. Allen
+
+
+      _General characters._--Pelage with lanceolate aristiforms limited
+      to an area on the dorsal surface between the shoulders and the
+      hips; length of tail less than 90 per cent of length of head and
+      body; skull with conspicuous ridges; extension of supraorbital
+      ridges always evident on parietals; infraorbital foramen usually
+      with separate groove for transmission of nerve; palate usually
+      extended posteriorly as far as third molars; incisors opisthodont;
+      molariform teeth with a small main fold, never extended
+      transversely to opposite wall in occlusal surface of tooth; usually
+      one counterfold anterior to main fold in upper molariform teeth and
+      posterior to main fold in lower molariform teeth; premolars usually
+      smaller than first molars, first molars smaller than second molars
+      but second molars larger than third molars.
+
+
+=Proechimys goeldii= Thomas
+
+      _General characters._--Size large; tail short; aristiforms narrow
+      and soft, usually concealed in pelage by setiforms; general color
+      of upper parts some tint of orange, gradually becoming lighter on
+      sides with no conspicuous, dark longitudinal band on back; feet
+      dark; ventral surface of body and inner side of legs white but
+      sometimes with some buff locally; skull broad and strongly built
+      but not conspicuously ridged; zygomatic expanse great and rostrum
+      not elongate; incisive foramen narrow; bullae large and inflated;
+      upper molariform teeth with three to four counterfolds, M3
+      ordinarily with four; lower premolars with four, and molars with
+      three, counterfolds.
+
+
+=Proechimys goeldii steerei= Goldman
+
+      _Proechimys steerei_ Goldman, Proc. Biol. Soc. Washington, 24:238,
+      28 November 1911 (original description); Goldman, 1912, Proc. Biol.
+      Soc. Washington, 25:186; Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119; Osgood, 1944, Zool. Ser.
+      Field Mus. Nat. Hist., 29(13):204.
+
+      _Type locality._--Hyutanaham, Upper Purus, _Lábrea_, Amazonas,
+      Brazil. _Type:_ United States National Museum, no. 105535, adult
+      male; collected in 1901 by Prof. J. B. Steere.
+
+      _Range._--Known only from the type locality and Porto Velho.
+
+      _Diagnosis._--Upper parts Mars Orange on back, grading to
+      Ochraceous-Tawny on sides; zygomatic breadth narrow; nasals short;
+      incisive foramen narrow and short; vomerine sheath complete and
+      thick; upper molars usually with four counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Grayish basally,
+      gradually blackening toward tip; total length, 16 to 19 mm;
+      maximum width, 0.5 mm. _Setiforms on middorsal region_: Grayish on
+      basal third, gradually blackening toward tip but interrupted by a
+      Mars Orange, subapical zone 1.5 mm long; total length, 16 to 19
+      mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Whitish
+      basally, gradually blackening toward tip but interrupted by Orange
+      Rufous or Ochraceous-Tawny, subapical zone; total length, 14 to 16
+      mm; maximum width, 0.05 mm.
+
+
+[Illustration: FIGS. 25, 27. _Proechimys goeldii steerei_, sex ?,
+"Hyutanaham," USNM no. 105537. × 1.]
+
+[Illustration: FIGS. 26, 28. _Proechimys goeldii goeldii_, female, AMNH
+no. 37488. × 1.]
+
+[Illustration: FIGS. 29, 30. _Proechimys goeldii steerei_, sex ?, USNM
+no. 105537, "Hyutanaham." × 1.]
+
+[Illustration: FIGS. 31, 32. _Proechimys goeldii goeldii_, female, AMNH
+no. 37488, Fazenda Paraiso. × 1.]
+
+      _Skull._--Large and strong; rostrum rather pointed posteriorly;
+      supraorbital ridges not much expanded and extending across
+      anterior half of parietals; infraorbital foramen without groove
+      for transmission of nerve, or groove obsolete; zygomatic arches
+      slender; postorbital process of zygoma involving mostly squamosal;
+      incisive foramen short and narrow (4.5 × 2.5 mm) with margins
+      almost parallel or tapering gradually caudad and extending toward
+      palate as ridges; posterior margin of incisive foramen
+      approximately 2.5 mm anterior to premolars; vomerine sheath
+      complete, with both elements well-developed; mesopterygoid fossa
+      never extending anterior to middle of M3; bullae large, well
+      inflated and with shallow grooves.
+
+      _Teeth._--Upper molariform teeth: P4 with three counterfolds;
+      upper molars with four counterfolds each or, less commonly, three.
+      Lower premolars with four counterfolds; lower molars with three
+      each.
+
+      _Comparisons._--From _P. g. goeldii_, _steerei_ differs in: Back
+      and sides with more reddish; narrower interorbitally and across
+      zygomata; palatilar length less and nasals shorter; maxillary part
+      of vomerine sheath thicker; usually four instead of three
+      counterfolds in M3.
+
+_Remarks._--This subspecies is clearly related to _P. goeldii_. One
+skull from Porto Velho, Rio Madeira, _Guaporé_, Brazil (CNHM no. 21558)
+may belong to an unnamed subspecies but is provisionally included here.
+
+In the field notes of Professor Joseph Beal Steere, an entry for no. 72
+reads: "Big white bellied wood rats x two young found in nest of grass
+on the ground with the two young--_much darker_ young female." No. 77 in
+his field notes corresponds to the type specimen.
+
+      _Specimens examined._--Total number, 4, from Brazil, as follows:
+      Amazonas. _Lábrea_, Hyutanaham, 3 (USNM); Territ. Guaporé, Porto
+      Velho, 1 (CNHM).
+
+
+=Proechimys goeldii goeldii= Thomas
+
+      _Proechimys goeldii_ Thomas, June 1905, Ann. Mag. Nat. Hist., 15
+      (ser. 7):587, (orig. descr.); Thomas, 1912, Ann. Mag. Nat. Hist., 9
+      (ser. 8):89; Thomas, 1920, Ann. Mag. Nat. Hist., 6 (ser. 9):277,
+      Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Osgood, 1944,
+      Zool. Ser. Field Mus. Nat. Hist., 29(13):199.
+
+      _Proechimys cayennensis goeldii_, Ellerman, 1940, The families and
+      genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121.
+
+      _Type locality._--Santarem, _Santarem_, Pará, Brazil. Type: British
+      Museum (Nat. Hist.), no. 5.1.25.6, adult female; presented by Dr.
+      E. A. Goeldi.
+
+      _Range._--Margins of the Amazon, between Jamundá and Tapajoz
+      rivers.
+
+      _Diagnosis._--Upper parts Ochraceous-Tawny; wide across zygomata;
+      nasals of moderate length; incisive foramen long and narrow;
+      vomerine sheath complete but maxillary part slender; first and
+      second upper molars with four counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally and
+      gradually blackening toward tip which is extended as long, thin
+      filament; total length, 22 to 24 mm; maximum width, 0.5 mm.
+      _Setiforms on middorsal region_: Gray basally, gradually
+      blackening toward tip but interrupted by Ochraceous-Tawny,
+      subapical zone 3.3 mm long; total length, 19 to 21 mm; maximum
+      width, 0.06 mm. _Setiforms on outer thighs_: Whitish basally,
+      gradually blackening toward tip but interrupted by
+      Ochraceous-Tawny, subapical zone 3 mm long; total length 14 to 16
+      mm; maximum width, 0.04 mm.
+
+      _Skull._--Large and strong; nasals pointed posteriorly;
+      supraorbital ridges moderately developed and extended caudad
+      across anterior third of parietals; zygomatic arches strong;
+      postorbital process of zygoma involving mostly squamosal; incisive
+      foramen elongate and narrow (5 to 6.5 x 2.3 mm) with margins more
+      or less parallel and raised to form ridges which extend posteriorly
+      to within 3 mm of plane of premolars; vomerine sheath complete,
+      with maxillary part thin and extended caudad as medial crest;
+      mesopterygoid fossa extending forward as far as posterior faces
+      of second molars or slightly short thereof; bullae large and
+      inflated.
+
+      _Teeth._--Molariform teeth large, P4-M3 averaging more than 9 mm
+      in length. Upper molariform teeth: P4 and M3 with three
+      counterfolds; M1 and M2 with four counterfolds each. In lower
+      teeth, p4 with four counterfolds and each molar with three
+      counterfolds.
+
+      _Comparisons._--Differences from _P. g. steerei_ are given in the
+      account of that subspecies.
+
+_Remarks._--Specimens from the type locality were not available.
+Specimens from Fazenda Paraiso, Faro, were relied upon as representative
+of the subspecies. These agree with the type according to Thomas
+(1912:89). However, the skin of the type was changed in color by
+preservative (Thomas, 1905:587) and the best skin he saw was from Faro
+(1912:89).
+
+Thomas (1920:277) applied the name _goeldii_ also to specimens from
+Manacaparú, a place a short distance above Manaus on the Solimões
+(Amazon) River and from Acajutuba, near Manaus, on the Negro River. In
+referring to these specimens (2 from Manacaparú and 2 from Acajutuba)
+Thomas (_loc. cit._) said "Five molar laminae are frequently, if not
+invariably, present among these specimens." He did not, however, mention
+whether or not the number of laminae was constant in both M2 and M3. One
+specimen from Acajutuba, in the collection of Museu Nacional (MN no.
+1973 [M]), actually has five laminae in M3, but the specimens in the
+American Museum from Faro agree absolutely with Thomas' original
+description of _goeldii_.
+
+Osgood (1944:199) doubted that _goeldii_ was a valid species. Evidence
+that Osgood's doubt was unjustified is furnished by the fact that Thomas
+(1912:89) pointed out that his specimen from Faro agrees with the type.
+Likewise, my two specimens from Faro agree with the type insofar as it
+has been described. Thomas (1912:89) mentioned two additional skulls
+from the type locality which, he stated, agree with the type which was
+received from the Museu Goeldi, Pará.
+
+      _Specimens examined._--Total number, 4, from Brazil as follows:
+      Pará, _Faro_, Faro, Fazenda Paraiso, 2 (AMNH); Amazonas, _Manaus_,
+      Manaus, 1 skull (AMNH); Amazonas, _Manaus_, Acajutuba, 1 (MN).
+
+      _Additional records._--Total number, 7 (British Museum), from
+      Brazil, as follows: Pará, _Santarem_, Santarem (Thomas, 1912:89;
+      1920:277), 3; Amazonas, _Manaus_, Acajutuba (Thomas, 1920:277), 2;
+      _Manacaparú_, Manacaparú (Thomas, 1920:277), 2.
+
+
+=Proechimys semispinosus= (Tomes)
+
+[Illustration: FIGS. 33, 36. _Proechimys semispinosus liminalis_,
+female, MN no. 6253, Rio Quichito. Type. × 1.]
+
+[Illustration: FIGS. 34, 37. _Proechimys semispinosus amphichoricus_,
+male, AMNH no. 77020, Mount Duida. Type. × 1.]
+
+[Illustration: FIGS. 35, 38. _Proechimys semispinosus kermiti_, female,
+AMNH no. 37124, Lower Rio Solimões. Type. × 1.2 (from photograph).]
+
+      _General characters._--Size large; tail short and hairy;
+      aristiforms wide and stiff, especially well-developed on back;
+      general color on upper parts some shade of ochraceous, usually much
+      darker on back and forming a conspicuous dorsal band; feet dark;
+      ventral surfaces and inner sides of legs white; skull elongate and
+      strong with ridges well developed; incisive foramen long and
+      narrow; bullae large; usually four counterfolds in M3 and M2;
+      usually three but sometimes four counterfolds in M1 and even P4;
+      lower premolar with four and lower molars with three counterfolds.
+
+[Illustration: FIGS. 39, 40. _Proechimys semispinosus liminalis_,
+female, MN no. 6253, Rio Quichito. Type. × 1.]
+
+[Illustration: FIGS. 41, 42. _Proechimys semispinosus amphichoricus_,
+male, AMNH no. 77020, Mount Duida. Type. × 1.]
+
+[Illustration: FIGS. 43, 44. _Proechimys semispinosus kermiti_, female,
+AMNH no. 37124, Lower Rio Solimões. Type. × 1.2 (from photograph).]
+
+
+=Proechimys semispinosus liminalis= subspecies nova
+
+      _Type locality._--Rio Quichito, affluent from the south of the
+      Javarí River, near _Benjamin Constant_, Benjamin Constant,
+      Amazonas, Brazil. _Type_: Museu Nacional, no. 6253, adult female,
+      collected in August, 1942, by E. Parko.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Color uniformly dark, setiforms marked with
+      Ochraceous-Tawny; skull wide across zygomata; nasals short;
+      prepalatilar part of skull long; incisive foramen long and narrow;
+      vomerine sheath incomplete or complete; M2 and M3 almost always
+      with four counterfolds; M1 more rarely with four counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip which is generally extended as a
+      filament; total length, 21 to 23 mm; maximum width, 0.9 to 1 mm.
+      _Setiforms on middorsal region_: Gray basally, gradually
+      blackening toward tip but interrupted by Ochraceous-Tawny,
+      subapical zone 3 mm long; total length, 22 to 24 mm; maximum
+      width, 0.06 mm. _Setiforms on outer thighs_: Whitish basally,
+      gradually blackening toward tip but interrupted by Ochraceous-Buff,
+      subapical zone 2.5 mm long; total length, 13 to 15 mm; maximum
+      width, 0.08 mm; some with gray base, blackening gradually toward
+      tip, without any subapical zone; some with Light Ochraceous-Tawny,
+      subapical zone.
+
+      _Skull._--Large and strongly built throughout; supraorbital ridges
+      expanded and thick, extending, in old specimens, across parietals
+      to anterior angles of interparietals; interparietal ridges always
+      conspicuous; rostrum elongated; nasals blunt posteriorly;
+      zygomatic arches strong; infraorbital foramen with
+      weakly-developed groove for transmission of nerve; postorbital
+      process of zygoma involving mostly squamosal; incisive foramen
+      averaging 6 x 2.7 mm, widest in middle part and posteriorly
+      constricted, with raised margins which do not extend across
+      maxillae as ridges; posterior margin of incisive foramen
+      approximately 1.5 mm anterior to plane of premolars; vomerine
+      sheath incomplete or, sometimes, complete but always with
+      maxillary part slender; mesopterygoid fossa not extending forward
+      past centers of third molars; bullae moderately developed.
+
+      _Teeth._--Upper molariform teeth: P4 always with three
+      counterfolds; M1 with three counterfolds in 9 of 10 specimens and
+      four counterfolds in remainder; M2 with four counterfolds in 7
+      specimens, three counterfolds in remainder; M3 with four
+      counterfolds in 6 specimens, three counterfolds in remainder.
+      Lower premolar always with four, and molars with three,
+      counterfolds.
+
+      _Comparisons._--From _P. s. semispinosus_, _liminalis_ differs in:
+      darker color; wider aristiforms; greater percentage of upper
+      molars with four counterfolds. From _P. s. amphichoricus_,
+      _liminalis_ differs in: lighter upper parts of almost uniform
+      color instead of with conspicuous, blackish, middorsal,
+      longitudinal band; more strongly built skull; longer incisive
+      foramen; vomerine sheath usually incomplete instead of always
+      complete.
+
+      _Specimens examined._--Total number, 10 (MN) from the type
+      locality.
+
+
+=Proechimys semispinosus amphichoricus= subspecies nova
+
+      _Type locality._--Mount Duida, Esmeralda, _Amazonas_, Venezuela;
+      altitude 325 m. _Type_: American Museum of Natural History, no.
+      77020, adult male; collected 16 October 1920 by Olalla Bros.
+
+      _Range._--Headwaters of Negro and Orinoco rivers, along boundary
+      of Brazil and Venezuela.
+
+      _Diagnosis._--Color dark, blackish on middorsal area; subapical
+      zone of setiforms on back Buckthorn Brown, but many with distal
+      parts black; skull broad across zygomata; nasals long;
+      prepalatilar area of skull long; incisive foramen long and narrow;
+      vomerine sheath complete; upper molars usually with four
+      counterfolds but P4 usually with only three.
+
+      _Pelage._--_Aristiforms on middorsal region_: Grayish basally,
+      gradually blackening toward tip; total length, 18 to 20 mm;
+      maximum width, 0.8 to 1.0 mm. _Setiforms on middorsal region_:
+      Gray basally, gradually blackening toward tip but interrupted by a
+      light (16 i), Buckthorn Brown, subapical zone 2 mm long; total
+      length, 18 to 22 mm; maximum width, 0.03 mm. Most of them,
+      however, whitish basally, gradually blackening toward tip without
+      any distinctively-colored, subapical zone; total length, 24 to 26
+      mm; maximum width, 0.5 mm. _Setiforms on outer thighs_: Whitish
+      basally, gradually blackening toward tip but interrupted by an
+      Ochraceous-Buff, subapical zone 3.5 mm long; black tip short; total
+      length, 17 to 19 mm; maximum width, 0.05 mm.
+
+_Skull._--Large and slender; rostrum elongate; nasals bluntly pointed
+posteriorly; supraorbital ridges thick (but not expanded) and extending
+across parietals but almost obsolete in middle part of parietals;
+infraorbital foramen with weakly-developed groove for transmission of
+nerve; postorbital process of zygoma involving mostly squamosal;
+incisive foramen 5.5 x 2.8 mm wide in anterior third, with margins
+constricted posteriorly and extending as ridges approximately 2 mm
+beyond posterior margin of incisive foramen; posterior margin of
+incisive foramen approximately 2.5 mm anterior to premolars; vomerine
+sheath complete with maxillary part weak and premaxillary part extending
+posteriorly beyond middle of incisive foramen; mesopterygoid fossa
+extending forward as far as middle of M3; bullae well inflated and
+elongated.
+
+_Teeth._--P4 with four counterfolds in one of five specimens and with
+three in remainder; M1 with four counterfolds in three of five specimens
+and with three in remainder; M2 with three counterfolds in one specimen
+and with four in all four remaining specimens; M3 always with four
+counterfolds. Lower premolars with four counterfolds and lower molars
+with only three.
+
+_Comparisons._--The subspecies is easily distinguishable from _P. s.
+angularis_ by: larger number of black setiforms on back, forming an
+almost black longitudinal band; more elongate skull; larger and longer
+bulla; longer incisive foramen which is more constricted posteriorly.
+
+      _Specimens examined._--Total number, 6 (AMNH), as follows:
+      Venezuela, territ. _Amazonas_, Esmeralda, Mt. Duida, altitude 325
+      m., 4; Venezuela, territ. _Amazonas_, Rio Cassiquiare, Quemapuré,
+      1; Brazil, Amazonas, _São Gabriel_, Rio Uaupés or Caiari, Tatú, 1.
+
+
+=Proechimys semispinosus kermiti= Allen
+
+      _Proechimys kermiti_ Allen, 30 December 1915, Bull. Amer. Mus. Nat.
+      Hist., 34(22):629 (orig. descr.); Allen, 1916, Bull. Amer. Mus.
+      Nat. Hist., 35(30):569; Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _Type locality._--Lower Rio Solimões (up the Solimões 50 to 60
+      miles on the north bank of the river), _Manacaparú_, Amazonas,
+      Brazil. _Type_: American Museum of Natural History, no. 37124,
+      adult female; collected 20 April, 1914, by Leo E. Miller (Roosevelt
+      Brazilian Expedition).
+
+      _Range._--Known only from type locality.
+
+      _Diagnosis._--Upper parts Tawny, with darker longitudinal band on
+      back, gradually becoming Ochraceous-Buff on sides; zygomata widely
+      spread; nasals long; incisive foramen long; vomerine sheath
+      incomplete; only M3 with four counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Grayish basally,
+      gradually blackening toward tip; total length, 18 to 20 mm;
+      maximum width, 0.8 mm. _Setiforms on middorsal region_: Grayish
+      basally, gradually blackening toward tip but interrupted by Tawny,
+      subapical zone 2 mm long; total length, 18 to 20 mm; maximum
+      width, 0.06 mm; some blackened toward tip without subapical zone.
+      _Setiforms on outer thighs_: Whitish basally, gradually blackening
+      toward tip but interrupted by Ochraceous-Buff, subapical zone
+      2.5 mm long; total length, 18 to 20 mm; maximum width, 0.05 mm.
+
+      _Skull._--Large, elongate, and strongly built; rostrum not
+      conspicuously elongated; nasals bluntly pointed posteriorly;
+      supraorbital ridges wide and extending posteriorly across parietals
+      almost to level of interparietal; infraorbital foramen with
+      moderate development of groove for transmission of nerve; zygomatic
+      arches slender; postorbital process of zygoma involving mostly
+      squamosal; incisive foramen 6.5 mm long and 2.7 mm wide, wider in
+      anterior third and gradually constricted posteriorly, with margins
+      extended toward palate as ridges; vomerine sheath incomplete,
+      maxillary part threadlike; mesopterygoid fossa extending forward as
+      far as anterior third of m3; bullae large and well inflated.
+
+      _Teeth._--P4 with three counterfolds; M3 with four counterfolds;
+      M1 and M2 with three counterfolds. Lower premolars with four
+      counterfolds; lower molars with three counterfolds.
+
+      _Comparisons._--From _P. s. amphichoricus_, _kermiti_ differs in:
+      upper parts Tawny instead of Buckthorn Brown; incisive foramen
+      longer and wider; vomerine sheath incomplete; only M3 instead of
+      usually all molars, with four counterfolds. From _P. s.
+      liminalis_, _kermiti_ differs in: upper parts Tawny instead of
+      Ochraceous-Tawny; aristiforms narrower; M3 only, instead of
+      usually M2 and M3, with four counterfolds.
+
+      _Specimens examined._--Only the type.
+
+
+=Proechimys longicaudatus= (Rengger)
+
+      _General characters._--Size medium to large; tail short;
+      aristiforms long and narrow; general color on upper parts
+      Ochraceous-Buff to Ochraceous-Orange, finely and uniformly lined
+      with blackish and not forming evident dark band on back; feet
+      dorsally white or gray; underparts of body and inner sides of legs
+      white; skull elongate and slender with moderate ridges; incisive
+      foramen of medium size; vomerine sheath complete or incomplete;
+      bullae large and elongate; upper molariform teeth with three
+      counterfolds; lower molariform teeth with three counterfolds but
+      commonly one or two molars have only two although premolar may have
+      four.
+
+_Remarks._--The identity of "_Echimys longicaudatus_ Rengger" can be
+ascertained only after samples have been collected in the area indicated
+by Rengger: "unter dem ein und zwansigsten Breitengrade" in Paraguay. Of
+the samples available to me, those from Urucum, in western Brazil, are
+geographically nearest the type locality. North of Urucum, both in
+Brazil and Bolivia, two species of _Proechimys_ live together and one of
+them is the same species as that at Urucum. Of the two species found to
+the northward in Brazil and Bolivia, the one that ranges farther south
+probably will occur at the locality indicated by Rengger. Provisionally,
+therefore, the name _longicaudatus_ is allocated to the Urucum sample
+(see Osgood, 1944:198). In fact, the lack of a type specimen and the
+general nature of Rengger's description make "_Echimys longicaudatus_" a
+_nomen vanum_. If two species are found living together in the region of
+northern Paraguay indicated by Rengger it probably will be impossible to
+be sure to which one his vague description applies.
+
+The form from Urucum, to which the name _Proechimys longicaudatus_ is
+here applied, is undoubtedly closely related to _Proechimys leucomystax_
+Ribeiro, from Utiarití, on the Rio Papagaio and also to _P. roberti_ and
+_P. boimensis_, all from Brazil. _P. longicaudatus_ is used as the name
+of the species because it is the oldest of the four names.
+
+[Illustration: FIGS. 45, 48. _Proechimys longicaudatus boimensis_, male,
+MCZ no. 30881, Boim. × 1.]
+
+[Illustration: FIGS. 46, 49. _Proechimys longicaudatus longicaudatus_,
+male, AMNH no. 37085, Urucum. × 1.]
+
+[Illustration: FIGS. 47, 50. _Proechimys longicaudatus leucomystax_,
+male, AMNH no. 37509, Tapirapoã. × 1.]
+
+[Illustration: FIGS. 51, 52. _Proechimys longicaudatus roberti_, male,
+MN no. 6233, Pouso Alto, Goiaz. × 1.]
+
+[Illustration: FIGS. 53, 54. _Proechimys longicaudatus boimensis_, male,
+MCZ no. 30881, Boim. × 1.]
+
+[Illustration: FIGS. 55, 56. _Proechimys longicaudatus longicaudatus_,
+male, AMNH no. 37085, Urucum. × 1.]
+
+[Illustration: FIGS. 57, 58. _Proechimys longicaudatus leucomystax_,
+male, AMNH no. 37509, Tapirapoã. × 1.]
+
+[Illustration: FIGS. 59, 60. _Proechimys longicaudatus roberti_, male,
+MN no. 6233, Pouso Alto, Goiaz. × 1.]
+
+
+=Proechimys longicaudatus brevicauda= (Günther)
+
+      _Echimys brevicauda_ Günther, 1 April 1877, Proc. Zool. Soc. London
+      for 1876, (49):748, fig. 9.
+
+      _Proechimys brevicauda_ Ihering, 1904, Rev. Mus. Paulista, S.
+      Paulo, 6:422; Osgood, 1914, Zool. Ser. Field Mus. Nat. Hist.,
+      10(12):168; Thomas, 1924, Ann. Mag. Nat. Hist., 13 (ser. 9):534;
+      Thomas, 1927, Ann. Mag. Nat. Hist., 19 (ser. 9):553; Thomas, 1927,
+      Ann. Mag. Nat. Hist., 20 (ser. 9):604; Thomas, 1928, Ann. Mag.
+      Nat. Hist., 2 (ser. 10):262; Thomas, 1928, Ann. Mag. Nat. Hist., 2
+      (ser. 10):292; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68
+      (5):399; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29
+      (13):201.
+
+      _Proechimys cayennensis brevicauda_ Ellerman, 1940, The families
+      and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:120.
+
+      _Type locality._--Chamicuros, Rio Huallaga, Peru. _Type_: British
+      Museum (Nat. Hist.), no. 69.3.31.7,[F]; _Lectoparatype_: British
+      Museum (Nat. Hist.), no. 66.1.29.8, from Upper Amazons (E.
+      Barttet), selected by Thomas (1900:301).
+
+      _Range._--Region of the headwaters and upper courses of the Juruá
+      and Ucaiali rivers, eastern Peru and northwestern Brazil.
+
+      _Diagnosis._--Upper parts Tawny and blackish without marked
+      longitudinal band on back; underparts buffy or white; aristiforms
+      narrow; skull slender; incisive foramen wide; vomerine sheath
+      complete; molariform teeth with three counterfolds, except p4 with
+      four and m3 with only two.
+
+      _Pelage._--_Aristiforms on middorsal region_: Blackish basally,
+      gradually blackening toward tip which is extended as a long
+      filament; total length, 18 to 20 mm; maximum width, 0.65 mm.
+      _Setiforms on middorsal region_: Gray basally, gradually
+      blackening toward tip but interrupted by Tawny, subapical zone 1.2
+      mm long; total length, 19 to 21 mm; maximum width, 0.1 mm.
+      _Setiforms on outer thighs_: Whitish basally, gradually blackening
+      toward tip but interrupted by Ochraceous-Tawny, subapical zone 3
+      mm long.
+
+      _Skull._--Slender but not elongated; nasals tapering posteriorly;
+      interparietals wide; supraorbital ridges not much extended and
+      faintly shown across parietals; jugals dorso-ventrally "wide" (3.5
+      mm); postorbital process of zygoma weakly developed; incisive
+      foramen 5.5 x 3 mm, oval, with posterior borders raised to form
+      ridges which extend toward premolars; vomerine sheath complete,
+      with maxillary part laterally compressed and extended toward
+      palate as ridge; mesopterygoid fossa extending forward as far as
+      third molars; bullae large and well inflated.
+
+      _Teeth._--Molariform teeth with three counterfolds, except p4
+      which has four and m3 which has only two counterfolds.
+
+      _Comparisons._--From _P. l. longicaudatus_, _brevicauda_ differs
+      in: upper parts Tawny instead of Ochraceous-Buff; lower premolar
+      with four instead of three counterfolds; m3 only, instead of both
+      m1 and m3, with two counterfolds. From _P. l. boimensis_,
+      _brevicauda_ differs in: upper parts Tawny instead of
+      Ochraceous-Orange; aristiforms wider; m3 with two instead of three
+      counterfolds.
+
+      _Specimens examined._--Total number, 3 (DZ), from Brazil, Amazonas,
+      _João Pessoa_, Rio Juruá.
+
+
+=Proechimys longicaudatus boimensis= J. A. Allen
+
+      _Proechimys boimensis_ Allen, 24 July, 1916, Bull. Amer. Mus. Nat.
+      Hist., 35(27):523; Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _Proechimys cayennensis_ Osgood, 1944, Zool. Ser. Field Mus. Nat.
+      Hist., 29(13):199.
+
+      _Type locality._--Boim, Rio Tapajoz, Santarem, Pará, Brazil.
+      _Type_: American Museum of Natural History, no. 37486, adult male;
+      "October 10, 1911 (ex Museu Goeldi)."
+
+      _Range._--Along lower course of Tapajoz River.
+
+      _Diagnosis._--Upper parts Ochraceous-Orange; incisive foramen
+      posteriorly constricted; mesopterygoid fossa sharply pointed
+      anteriorly; p4 with four counterfolds, remaining molariform teeth
+      with three counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip which is extended as a long
+      filament; total length, 16 to 18 mm; maximum width, 0.5 mm.
+      _Setiforms on middorsal region_: Gray basally, gradually
+      blackening toward tip, but interrupted by short (1.5 mm),
+      Ochraceous-Orange, subapical zone; total length 18 to 20 mm;
+      maximum width 0.09 mm. _Setiforms on outer thighs_: White basally,
+      gradually blackening toward tip but interrupted by
+      Ochraceous-Orange, or Ochraceous-Buff, subapical zone 3.5 mm long;
+      total length 15 to 17 mm; maximum width, 0.06 mm.
+
+      _Skull._--Elongate and slender; rostrum slender and long; nasals
+      evenly pointed posteriorly; supraorbital ridges weak and barely
+      reaching anteriormost part of parietals; zygomatic arches slender;
+      infraorbital foramen with groove for nerve-transmission obsolete;
+      postorbital process of zygoma weak and involving mostly squamosal;
+      incisive foramen 5 mm long and 2.5 to 3 mm wide, oval, with
+      margins not much extended caudad as ridges; posterior margin of
+      incisive foramen approximately 2 mm anterior to premolars;
+      vomerine sheath complete with maxillary part slender;
+      mesopterygoid fossa sharply pointed anteriorly and extending
+      forward as far as anterior part of third molar; bullae of medium
+      size, smooth and more or less triangular in contour.
+
+      _Teeth._--Crown length of upper molariform teeth 7 to 7.5 mm; all
+      upper molariform teeth with three counterfolds; lower premolar
+      with four counterfolds; lower molars with three counterfolds each.
+
+      _Comparisons._--From three of the other four subspecies found in
+      Brazil, _boimensis_ differs in having four, instead of three,
+      counterfolds in the lower premolars. Differences from _P. l.
+      brevicauda_ are indicated in the account of that subspecies.
+
+_Remarks._--The material available from Boim, Tapajoz, is rather poor
+and of no great significance. The Museu Nacional has one specimen from
+Boim which agrees with the type in the American Museum of Natural
+History. The Museum of Comparative Zoology at Harvard College, however,
+has one specimen in its collection (MCZ no. 30888 [M]), adult, also from
+Boim, in which the color pattern is different although agreement with
+the type specimen is shown in cranial characters and width and length of
+hairs. This specimen is much darker than the other specimens (of
+orange-tint) assigned to this subspecies. However, in other samples of
+this species, similarly dark animals have been noted. It seems that the
+orange tint is gained only in old age. Another specimen (MCZ no. 30878
+[F]) agrees in all respects with the type of the subspecies but the
+locality recorded on the label is Cametá, on the Tocantins River.
+Possibly the subspecies has a range so wide as to include Cametá but I
+suspect that the data on the label is incorrect as to locality. The
+collector marked [M] on the label although the specimen is a [F]. The
+mistake might have occurred through labeling of specimens at a time
+later than that at which they were collected. The collector was in both
+localities on more than one occasion.
+
+      _Specimens examined._--Total number, 5, from Brazil, Pará, as
+      follows: _Santarem_, Rio Tapajoz, Boim, 3 (AMNH type, MCZ 1, MN 1);
+      _Porto de Moz_, Tauarí, 1 (MCZ); _Cametá_ (?) 1 (MCZ).
+
+
+=Proechimys longicaudatus longicaudatus= (Rengger)
+
+      _Echimys longicaudatus_ Rengger, 1830, Naturgeschichte der
+      Saeugethiere von Paraguay, p. 236.
+
+      _Loncheres myosuros_ Lichtenstein, 1832, Darstellung neuer oder
+      wenig bekannter Säugethiere, pl. 36 and text.
+
+      _Echimys myosuros Is._ Geoffroy Saint-Hilaire, 1840, Mag. Zool.,
+      Ann. 2 (ser. 2):15, 17; Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):261.
+
+      _Echimys cayennensis_ Pictet, 1841, Mém. Soc. Phys. Hist. Nat.,
+      Genéve, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334.
+
+      _Proechimys longicaudatus_ Thomas, 1901, Ann. Mag. Nat. Hist., 8
+      (ser. 7):532; Thomas, 1904, Proc. Zool. Soc. London, p. 240;
+      Allen, 1916, Bull. Amer. Mus. Nat. Hist., 35(30):569; Tate, 1935,
+      Bull. Amer. Mus. Nat. Hist., 68(5):400.
+
+      _Proechimys cayennensis longicaudatus_ Ellerman, 1940, The
+      families and genera of living rodents, Brit. Mus. (Nat. Hist.),
+      1:121; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist, 29(13):198.
+
+      _Type locality._--Northern Paraguay ("unter dem ein und zwansigsten
+      Breitengrade"). _Type_: Apparently no type specimen was
+      preserved.
+
+      _Range._--Western Mato Grosso, Brazil, and northern Paraguay.
+
+      _Diagnosis._--Upper parts almost uniformly Ochraceous-Buff;
+      incisive foramen widest posteriorly; vomerine sheath complete; p4
+      and m2 with three counterfolds; m1 and m3 usually with two
+      counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Dark gray, gradually
+      blackening toward tip that has long filament; total length 20 to
+      22 mm; maximum width 0.6 mm. _Setiforms on middorsal region_:
+      Whitish basally, gradually blackening toward tip but interrupted
+      by Ochraceous-Buff, subapical zone; blackish tip extended (3.5 mm)
+      and thin; total length 19 to 20 mm; maximum width 0.06 mm.
+      _Setiforms on outer thighs_: Whitish basally, progressively
+      grayish or blackish toward tip but interrupted by Light
+      Ochraceous-Buff or Ochraceous-Buff, subapical zone; total length
+      18 to 20 mm; maximum width 0.06 mm.
+
+      _Skull._--Slender; supraorbital ridge notably raised; bullae
+      large, elongate, smooth and inflated; jugals narrow; postorbital
+      process of zygoma of medium size and constructed entirely of
+      jugal; incisive foramen wide and large (5.5 x 3 mm), being
+      wider posteriorly than anteriorly and with posterior margins
+      raised; vomerine sheath complete, maxillary part slender
+      and laterally flattened; mesopterygoid fossa extending forward as
+      far as centers, or anterior margins, of third molars; posterior
+      palatine foramina on plane with posterior faces, or centers, of
+      second molars.
+
+      _Teeth._--Upper molariform teeth always with three counterfolds.
+      Lower molariform teeth: p4 and m2 always with three counterfolds,
+      sometimes the two anterior ones coalesced in m2; m1 with three
+      counterfolds in one specimen (33 per cent); m3 with only two
+      counterfolds in all specimens.
+
+      _Comparisons._--Differences from _P. l. leucomystax_ and _P. l.
+      roberti_ are given in the accounts of those subspecies.
+
+      _Specimens examined._--Total number, 3 (2 AMNH, 1 CNHM), from
+      Brazil, Mato Grosso, _Corumbá_, Urucum.
+
+
+=Proechimys longicaudatus leucomystax= Ribeiro
+
+      _Proechimys leucomystax_ Ribeiro, May, 1914, Commissão de linhas
+      telegraphicas estrategicas de Matto Grosso ao Amazonas, Annexo no.
+      5. Hit. Nat., Zool., Mammiferos, p. 42, pl. 24 (orig. descr.);
+      Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940,
+      The families and genera of living rodents, Brit. Mus. (Nat. Hist.),
+      1:119.
+
+      _Type locality._--Utiarití, Rio Papagaio, Diamantion, Mato Grosso,
+      Brazil. _Type_: Museu Nacional, no. 2212, adult, skull only,
+      collected on 5 May 1909, by Prof. A. Miaranda Ribeiro, is here
+      designated _lectotype_. See remarks.
+
+      _Range._--Serra dos Parecís, Mato Grosso, Brazil.
+
+      _Diagnosis._--Ochraceous-Buff, richly lined with blackish, on
+      upper parts; some setiforms completely blackened distally;
+      incisive foramen regularly ovoid; vomerine sheath incomplete;
+      upper molariform teeth and lower premolar with three counterfolds;
+      m2 with three counterfolds but m1 and m3 usually with two
+      counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Grayish basally,
+      gradually blackening toward tip which is extended as a long
+      filament; total length 21 to 22 mm; maximum width 0.65 mm.
+      _Setiforms on middorsal region_: Whitish basally, gradually
+      blackening toward tip but interrupted by Ochraceous-Buff,
+      subapical zone; some setiforms grayish basally and gradually
+      blackening toward distal portion without any colored, subapical
+      zone; total length 20 to 22 mm, maximum width 0.06 mm. _Setiforms
+      on outer thigh_: White basally, gradually becoming gray toward tip
+      but interrupted by Light Ochraceous-Buff, subapical zone; some
+      setiforms gray basally and blackening toward tip, but interrupted
+      by Ochraceous-Buff, subapical zone; total length 15 to 18 mm;
+      maximum width 0.08 mm.
+
+      _Skull._--Slender; supraorbital ridges conspicuous; bullae large,
+      smooth and inflated, with slight, transverse groove; jugals
+      narrow; postorbital processes of zygomata small and involving only
+      squamosal; incisive foramen of medium size but narrow (5 x 2.5
+      mm), regularly oval and with margins uplifted posteriorly;
+      vomerine sheath incomplete but maxillary part projecting forward
+      and sometimes almost reaching premaxillary part; mesopterygoid
+      fossa reaching forward as far as centers of third molars;
+      posterior palatine foramina at plane of posterior faces of second
+      molars or slightly anterior thereto.
+
+      _Teeth._--Upper molariform teeth with three counterfolds. Lower
+      molariform teeth: p4 and m2 always with 3 counterfolds; m1 and m3
+      with 2 counterfolds.
+
+      _Comparisons._--From _P. l. longicaudatus_, _leucomystax_ differs
+      in: upper parts richly lined, instead of scarcely lined, with
+      blackish; incisive foramen narrower, and regularly oval instead of
+      widest anteriorly.
+
+      _Remarks._--_Proechimys leucomystax_ was described mainly on the
+      basis of the Utiarití specimen, here designated lectotype of the
+      species. The specimen from the Juina River is younger, as stated
+      by Ribeiro in his description. Ribeiro mentions the skin of the
+      specimen from Utiarití as "em muito mao estado" and I presume it
+      was discarded as it has not been found in the collection of the
+      Museu Nacional, Brazil.
+
+      _Specimens examined._--Total number, 6, from Brazil, Mato Grosso:
+      Cáceres, Salto Sepotube, 2 (MN); Cáceres, Tapirapoã, Rio Sepotuba,
+      2 (AMNH); _Diamantino_, Utiarití, Rio Papagaio, 1 skull (MN);
+      _Diamantino_, Rio Juina, 1 (MN).
+
+
+=Proechimys longicaudatus roberti= Thomas
+
+      _Proechimys roberti_ Thomas, December, 1901, Ann. Mag. Nat. Hist.,
+      8 (ser. 7):531 (orig. descr.); Thomas, 1904, Ann. Mag. Nat. Hist.,
+      14 (ser. 7):195; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser.
+      9):140; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400.
+
+      _Proechimys cayennensis roberti_ Ellerman, 1940, The families and
+      genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121.
+
+      _Type locality._--Rio Jordão, _Araguarí_, Minas Gerais, Brazil; 960
+      meters alt. _Type_: British Museum (Nat. Hist.), no. 1.11.3.62, old
+      male, collected 8 August, 1902, by A. Robert; original number, 705.
+
+      _Range._--Western Minas Gerais and southern Goiaz.
+
+      _Diagnosis._--Color almost uniformly Ochraceous-Orange on upper
+      parts; setiforms long and narrow; incisive foramen long and wide;
+      vomerine sheath usually complete; upper molariform teeth and lower
+      premolar with three counterfolds; m3 with two, and m1 and m2 with
+      two or three, counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually blackening toward tip; total length, 21 to 23 mm;
+      maximum width, 0.6 mm. _Setiforms on middorsal region_: Whitish on
+      basal half, gradually blackening toward tip but interrupted by an
+      Ochraceous-Orange, subapical zone 6 to 7 mm long; total length 25
+      to 30 mm; maximum width, 0.05 mm. _Setiforms on outer thighs_:
+      Whitish on basal half, gradually becoming gray and then blackish
+      toward tip but interrupted by wide, Ochraceous-Buff, subapical
+      zone, the tip being brownish or blackish; total length, 22 to 23
+      mm; maximum width, 0.04 mm.
+
+      _Skull._--Slender; supraorbital ridges bent outward and making
+      sharp angle at point of frontosquamosal suture, then continuing
+      backward parallel to each other and extending across parietals;
+      squamosal taking small part in supraorbital ridges; bullae large
+      (11 x 8 mm), inflated, with shallow depressions; incisive foramen
+      not especially long but wide (5 x 3 to 3.5 mm), widest in anterior
+      third and constricted posteriorly; vomerine sheath usually
+      complete, with maxillary part reduced to slender threadlike
+      process or, less commonly, missing; mesopterygoid fossa extending
+      forward as far as centers of third molars; zygomatic arches strong
+      with jugals of medium dorsoventral width (approximately 3.5 mm);
+      postorbital process of zygoma weakly developed and involving only
+      squamosal; posterior palatine foramina on plane of posterior
+      margins of first molars or slightly anterior thereto.
+
+[Illustration: FIG. 61. Map showing the geographic ranges of the
+subspecies of three species of the subgenus _Proechimys_ in Brazil.]
+
+      _Teeth._--Upper molariform teeth usually with three counterfolds
+      (92.5 per cent of 42 specimens); M2 with four counterfolds in 5 per
+      cent of specimens; M3 with two counterfolds in 2.5 per cent of
+      specimens. Lower molariform teeth: p4 usually with three
+      counterfolds (97.5 per cent of 39 specimens); rarely with four (2.5
+      per cent); m1 with three counterfolds in 58 per cent and two
+      counterfolds in 42 per cent of specimens; m2 with three
+      counterfolds in 61 per cent and two counterfolds in 39 per cent of
+      specimens; m3 always with only two counterfolds.
+
+      _Comparisons._--From _P. l. boimensis_, _roberti_ differs in: wider
+      incisive foramen; lower premolar with three, and one or two lower
+      molars with only two, counterfolds, instead of lower premolar with
+      four and all lower molars with three counterfolds. From _P.
+      longicaudatus_, _roberti_ differs in: upper parts Ochraceous-Orange
+      instead of Ochraceous-Buff; incisive foramen wider in posterior
+      third than in anterior third.
+
+_Remarks._--This subspecies seems to be adapted to forests of
+post-climactic conditions which is probably typical of most valleys and
+margins of the rivers in southern Goiaz and western Minas Gerais. It was
+found in Goiaz usually in riparian forests with climactic associations
+or in some advanced stage of the sere. The animals also make incursions
+into nearby open areas or crops of corn.
+
+      _Specimens examined._--Total number, 52, from Brazil, as follows:
+      Minas Gerais, _Araguarí_, Rio Jordão (effluent of Parnaiba), 960
+      meters alt., 2 (1 CNHM, 1 DZ); Goiaz, _Anapolis_, 1010 meters alt.,
+      38 (MN); Goiaz, _Pouso Alto_, 768 meters alt., 11 (MN); Goiaz, Tio
+      São Miguel, 2 (MN).
+
+
+=Proechimys guyannensis= (E. Geoffroy)
+
+      _Mus guyannensis_ E. Geoffroy Saint-Hilaire, 1803, Catalogue des
+      mammifères du Museum d'Histoire Naturelle, Paris, p. 194.
+
+      _Echimys cayennensis_ Desmarest, 1817, Nouv. Dict. Hist. Nat.,
+      Paris, nouv. ed., 10:59.
+
+      _Proechimys cayennensis_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):261, 264; Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):399; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:120.
+
+      _General characters._--Size medium to large; tail usually short;
+      aristiforms narrow to wide; general color of setiforms on back
+      ranging from Tawny to Ochraceous-Buff and becoming gradually
+      lighter on sides; no conspicuous dark longitudinal band on back;
+      upper parts of hands and feet white to light brown; underparts
+      white, including inner sides of legs; skull elongate and not
+      conspicuously ridged; vomerine sheath complete or incomplete; upper
+      premolar with three counterfolds and molars with two or three;
+      lower premolar with three or four counterfolds, and lower molars
+      with two or three.
+
+
+=Proechimys guyannensis villicauda= subspecies nova
+
+      _Type locality._--Tapirapoã, Rio Sepotuba, _Cáceres_, Mato Grosso,
+      Brazil. _Type_: Museu Nacional, no. 1932, adult male (color faded);
+      collected on 2 February, 1909, by Prof. A. Miranda Ribeiro;
+      original number, 788 A.
+
+      _Range._--Serra dos Parecís, headwaters of Paraguai and Tapajoz
+      rivers.
+
+      _Diagnosis._--Aristiforms wide and stiff; general color on upper
+      parts Ochraceous-Orange; incisive foramen long; vomerine sheath
+      incomplete or complete; lower premolar with four counterfolds,
+      remaining molariform teeth with three counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually becoming gray toward tip, with distal fourth blackish
+      and ending as a long filament; total length, 22 to 23 mm; maximum
+      width, 1 mm. _Setiforms on middorsal region_: Whitish on basal
+      half, gradually blackening toward tip but interrupted by
+      Ochraceous-Orange, subapical zone 5 mm long; total length, 26 to
+      30 mm; width, 0.04 to 0.12 mm. _Setiforms on outer thighs_: Whitish
+      on basal half, gradually blackening toward tip but interrupted by
+      Ochraceous-Buff to Ochraceous-Orange subapical zone; total length
+      20 to 23 mm; width, 0.03 to 0.18 mm.
+
+      _Skull._--Strong; supraorbital ridges raised and extending across
+      anterior fourth of parietals; nasals elongate; bullae rounded,
+      inflated, with shallow grooves; postorbital process of zygoma
+      weakly developed and constructed entirely of jugal; incisive
+      foramen elongate and narrow (5.5 x 2.5 mm), posteriorly constricted
+      with posterior margins elevated above surface of bones; vomerine
+      sheath incomplete or complete but, when complete, with maxillary
+      part filiform and delicate; mesopterygoid fossa extending forward
+      as far as middle, or even anterior, parts of third molars;
+      posterior palatine foramina on plane of centers, or even anterior
+      faces, of second molars.
+
+      _Teeth._--Upper molariform teeth with three counterfolds. Lower
+      molariform teeth: premolar with four counterfolds, molars with
+      three counterfolds, sometimes with two folds coalesced in center
+      of tooth.
+
+      _Comparison._--From _P. g. ribeiroi_, and _P. g. bolivianus_,
+      _villicauda_ differs in wider aristiforms. From _P. g. ribeiroi_,
+      _villicauda_ further differs in: larger and wider incisive
+      foramen; vomerine sheath incomplete or complete instead of always
+      complete and thick. From _P. g. bolivianus_, _villicauda_ differs
+      in: lower premolars always, instead of rarely, with four
+      counterfolds, and m3 always with three counterfolds instead of
+      usually with only two counterfolds.
+
+      _Specimens examined._--Total number, 4, from Brazil, Mato Grosso,
+      as follows: _Cáceres_, Tapirapoã, 3 (MN); _Diamantino_, Rio
+      Papagaio, Utiarití, 1 (AMNH).
+
+[Illustration: FIG. 62.
+_Proechimys guyannensis villicauda_, male, MN no. 1932, Tapirapoã.
+Type. × 1.]
+
+[Illustration: FIG. 63. _Proechimys guyannensis ribeiroi_, male, MN no.
+1935, Rio Doze de Outubro. Type. × 1.]
+
+[Illustration: FIG. 64. _Proechimys guyannensis hyleae_, male, MCZ no.
+30887, Tauarí. Type. × 1.]
+
+[Illustration: FIG. 65. _Proechimys guyannensis nesiotes_, male, CNHM
+no. 19496, Ilha de Manapirí. Type. × 1.]
+
+[Illustration: FIG. 66. _Proechimys guyannensis leioprimna_, female,
+CNHM no. 19503, Cametá. Type. × 1.]
+
+[Illustration: FIG. 67. _Proechimys guyannensis oris_, male, CNHM no.
+19495, Providencia. × 1.]
+
+[Illustration: FIG. 68. _Proechimys guyannensis arescens_, male, CNHM
+no. 26440, Fazenda Inhuma. Paratype. × 1.]
+
+[Illustration: FIG. 69. _Proechimys guyannensis riparum_, female, AMNH
+no. 143018, Manaus. Type. × 1.]
+
+[Illustration: FIG. 70. _Proechimys guyannensis arabupu_, male, AMNH no.
+75816, Arabupu. Type. × 1.]
+
+[Illustration: FIG. 71. _Proechimys guyannensis villicauda_, male, MN
+no. 1932, Tapirapoã. Type. × 1.]
+
+[Illustration: FIG. 72. _Proechimys guyannensis ribeiroi_, male, MN no.
+1935, Rio Doze de Outubro. Type. × 1.]
+
+[Illustration: FIG. 73. _Proechimys guyannensis hyleae_, male, MCZ no.
+30887, Tauarí. Type. × 1.]
+
+[Illustration: FIG. 74. _Proechimys guyannensis nesiotes_, male, CNHM
+no. 19496, Ilha de Manapirí. Type. × 1.]
+
+[Illustration: FIG. 75. _Proechimys guyannensis leioprimna_, female,
+CNHM no. 19503, Cametá. Type. × 1.]
+
+[Illustration: FIG. 76. _Proechimys guyannensis oris_, male, CNHM no.
+19495, Providencia. × 1.]
+
+[Illustration: FIG. 77. _Proechimys guyannensis arescens_, male, CNHM
+no. 26440, Fazenda Inhuma. Paratype. × 1.]
+
+[Illustration: FIG. 78. _Proechimys guyannensis riparum_, female, AMNH
+no. 143018, Manaus. Type. × 1.]
+
+[Illustration: FIG. 79. _Proechimys guyannensis arabupu_, male, AMNH no.
+75816, Arabupu. Type. × 1.]
+
+[Illustration: FIGS. 80, 81. _Proechimys guyannensis villicauda_, male,
+MN no. 1932, Tapirapoã. Type. × 1.]
+
+[Illustration: FIGS. 82, 83. _Proechimys guyannensis ribeiroi_, male, MN
+no. 1935, Rio Doze de Outubro. Type. × 1.]
+
+[Illustration: FIGS. 84, 85. _Proechimys guyannensis hyleae_, male, MCZ
+no. 30887, Tauarí. Type. × 1.]
+
+[Illustration: FIGS. 86, 87. _Proechimys guyannensis nesiotes_, male,
+CNHM no. 19496, Ilha de Manapirí. Type. × 1.]
+
+[Illustration: FIGS. 88, 89. _Proechimys guyannensis leioprimna_,
+female, CNHM no. 19503. Type. × 1.]
+
+[Illustration: FIGS. 90, 91. _Proechimys guyannensis oris_, male, CNHM
+no. 19495, Providencia. × 1.]
+
+[Illustration: FIGS. 92, 93. _Proechimys guyannensis arescens_, male,
+CNHM no. 26440, Fazenda Inhuma. Paratype. × 1.]
+
+[Illustration: FIGS. 94, 95. _Proechimys guyannensis riparum_, female,
+AMNH no. 143018, Manaus. Type. × 1.]
+
+[Illustration: FIGS. 96, 97. _Proechimys guyannensis arabupu_, male,
+AMNH no. 75816, Arabupu. Type. × 1.]
+
+
+=Proechimys guyannensis ribeiroi= subspecies nova
+
+      _Type locality._--Rio 12 de Outubro, affluent of the Camararé,
+      _Mato Grosso_, Mato Grosso, Brazil; about 190 kilometers west of
+      Utiarití; altitude 414 meters. _Type_: Museu Nacional, no. 1935,
+      adult male (colors faded); collected on 20 June, 1909, by Prof. A.
+      Miranda Ribeiro; original number _G._
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--_Aristiforms wide and stiff_; incisive foramen small
+      and narrow; vomerine sheath complete and thick; p4 with four
+      counterfolds; remaining molariform teeth with three counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually blackening toward tip; total length, 19 to 22 mm;
+      maximum width, 0.8 mm. _Setiforms on middorsal region_: Whitish on
+      basal half, gradually blackening toward tip but interrupted by
+      subapical zone probably of some tint of ochraceous; total length,
+      22 to 24 mm; maximum width, 0.06 mm. _Setiforms on outer thighs_:
+      Whitish basally, gradually blackening toward tip but interrupted
+      by probably light ochraceous, subapical zone; total length 14 to
+      16 mm; maximum width, 0.03 mm.
+
+      _Skull._--Slender; supraorbital ridges low; bullae ovate with
+      shallow grooves; postorbital process of zygoma almost obsolete and
+      involving mostly jugal; incisive foramen short and narrow (4 × 2
+      mm), constricted posteriorly and with posterior margins raised;
+      vomerine sheath complete and thick; mesopterygoid fossa extending
+      forward as far as posterior faces of second molars; posterior
+      palatine foramina on plane with centers of second molars.
+
+      _Teeth._--Upper molariform teeth with three counterfolds. Lower
+      molariform teeth: p4 with four counterfolds; molars with three
+      counterfolds which sometimes are fused.
+
+      _Comparisons._--From _P. g. bolivianus_, _ribeiroi_ differs in:
+      aristiforms wider; incisive foramen shorter and narrower; vomerine
+      sheath complete and thick, instead of complete or incomplete and
+      not thick; p4 always with four, instead of usually only three,
+      counterfolds and lower molars always with three, instead of
+      sometimes with only two, counterfolds in m3. Differences from _P.
+      g. villicauda_ are given in the account of that subspecies.
+
+_Remarks._--The name _ribeiroi_ is given in honor of the late Professor
+Alipio Miranda Ribeiro, in recognition of his important work in
+Brazilian vertebrate zoology.
+
+      _Specimens examined._--Total number, 2 (MN), from Brazil, Mato
+      Grosso, _Mato Grosso_, Rio 12 de Outubro; altitude, 414 meters.
+
+
+=Proechimys guyannensis hyleae= subspecies nova
+
+      _Type locality._--Tauarí, Rio Tapajoz, _Porto de Moz_, Pará,
+      Brazil; approximately 87 kilometers south of Santarem. _Type_:
+      Museum of Comparative Zoology at Harvard College, no. 30887, adult
+      male; collected on 19 January, 1934, by A. M. Olalla; original
+      number 7288.
+
+      _Range._--Region of lower Tapajoz River and banks of Amazon up to
+      the Jamundá River.
+
+      _Diagnosis._--Aristiforms conspicuously wide and stiff; general
+      color on upper parts Tawny; incisive foramen long and oval;
+      vomerine sheath complete but with maxillary part slender or,
+      sometimes, incomplete; p4 with four counterfolds, rarely three;
+      remaining molariform teeth with three counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually becoming blackish toward tip; total length, 19 to 21 mm;
+      maximum width, 1.1 mm. _Setiforms on middorsal region_: a. Gray
+      basally, gradually blackening toward tip but interrupted by wide (5
+      to 6 mm) Tawny, subapical zone; some are whitish basally and
+      gradually become sooty brown toward tip except for same type of
+      subapical zone (tip only slightly darker than subapical zone); b.
+      With the same type described above and some completely blackish,
+      with the base gray; total length 22 to 25 mm; maximum width, 0.1
+      mm. _Setiforms on outer thighs_: Whitish basally, gradually
+      becoming gray and then blackish toward tip but interrupted by long,
+      Ochraceous-Tawny, subapical zone; tip, itself, blackish brown;
+      sometimes this type appears with some lighter ones and sometimes
+      with completely blackish setiforms; total length 16 to 18 mm;
+      maximum width 0.3 mm.
+
+      _Skull._--Medium in size and slender; cranium narrow and not
+      increasing much in breadth posteriorly; rostrum stout, laterally
+      thick, with masseteric crest well-developed; nasals pointed
+      posteriorly; supraorbital ridges broad but barely extended across
+      parietals; zygomatic arches strong; postorbital process of zygoma
+      involving mostly squamosal; incisive foramen long and narrow (5.5
+      to 6 × 2.5 mm), oval and extending posteriorly to point only 2 mm
+      anterior to premolars; vomerine sheath complete with maxillary
+      part usually slender; mesopterygoid fossa extending forward as far
+      as centers of third molars; bulla of medium size, well inflated
+      and with shallow grooves on surface.
+
+      _Teeth._--Upper molariform teeth with three counterfolds. Lower
+      premolar with four counterfolds or, sometimes (20 per cent of 15
+      specimens), with only three; lower molars with three counterfolds.
+
+      _Comparisons._--From _P. g. oris_ and _P. g. nesiotes_, _hyleae_
+      differs in: wider aristiforms; general color on upper parts Tawny,
+      instead of Ochraceous-Orange; vomerine sheath not always complete,
+      instead of always complete. From _P. g. oris_, _hyleae_ differs
+      in: p4 usually with four, instead of only three counterfolds and
+      all molars with three, instead of only lower molars with three
+      counterfolds. From _P. g. nesiotes_, _hyleae_ differs in: p4
+      usually, instead of always, with four counterfolds; color on back
+      Tawny instead of Ochraceous-Orange; aristiforms wider.
+
+_Remarks._--This subspecies shows greater variability than any other in
+this species. There are two types of coloration. The most common type of
+coloration is dark, with Tawny, subapical zones in the setiforms of the
+middorsal region and many completely black setiforms; in the other type
+the subapical zone is still Tawny but there are no black setiforms. One
+specimen from Obidos, on the north bank of the Amazon, completely agrees
+in the characteristics of color and skull with the reddish type and
+suggests either that there is an extension of the range of the
+subspecies along the lower course of the Tapajoz or that there are two
+subspecies, in which event the animals from Tauarí are intergrades
+between _hyleae_ and an unnamed, tawny-colored subspecies occurring to
+the southward.
+
+Between 13 and 23 January, 1934, A. M. Olalla collected 10 adult
+females, 6 of which contained embryos. Three of the females had 2
+embryos each, two had 3 embryos each and one had only 1 embryo. At this
+same time and place only ten per cent of specimens obtained were not
+fully adult.
+
+      _Specimens examined._--Total number, 21, from Brazil, Pará, as
+      follows: _Porto de Moz_, Tauarí, right bank of Tapajoz,
+      approximately 85 kilometers south of Santarem, 20 (19 MCZ, 1 CNHM);
+      _Obidos_, Obidos, 1 (MCZ).
+
+
+=Proechimys guyannensis nesiotes= subspecies nova
+
+      _Type locality._--Ilha de Manapirí, Rio Tocantins, Pará,
+      Brazil. _Type_: Chicago Natural History Museum, no. 19496, adult
+      male; collected on 9 December, 1910, by Dr. Emilia Snethlage;
+      original number, 12.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms wide and stiff; general color on upper
+      parts Ochraceous-Orange; incisive foramen long, with parallel
+      borders; vomerine sheath complete and thick; p4 with four
+      counterfolds, remaining molariform teeth with three counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 18 to 19 mm;
+      maximum width, 0.9 mm. _Setiforms on middorsal region_: Gray
+      basally, gradually blackening toward tip but interrupted by
+      Ochraceous-Orange, subapical zone 4 mm long; total length 16 to 19
+      mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Whitish
+      basally, gradually becoming gray and blackish toward tip but
+      interrupted by Ochraceous-Buff, subapical zone 3 mm long; total
+      length, 13 to 15 mm; maximum width, 0.03 mm.
+
+      _Skull._--Of medium size; rostrum short; nasals pointed
+      posteriorly; postorbital ridges extending caudad across anterior
+      fifth of parietals; zygomatic arches strong; jugal with process in
+      posterior part of masseteric fossa; postorbital process of zygoma
+      involving mostly squamosal; incisive foramen elongate, narrow (5 x
+      2.3 mm), and parallel sided; posterior margin of incisive foramen
+      approximately 3 mm anterior to premolars; margins of foramen
+      raised to form ridges; vomerine sheath complete, of almost uniform
+      width and set deeply in foramen; mesopterygoid fossa extending
+      forward as far as centers of third molars; bullae of medium size
+      and inflated.
+
+      _Teeth._--Upper molariform teeth with three counterfolds; p4 with
+      four counterfolds; m1-3 with three counterfolds.
+
+      _Comparison._--_From P. g. oris_, _nesiotes_ differs in:
+      Aristiforms conspicuously wider; incisive foramen shorter and
+      narrower, with borders parallel instead of posteriorly
+      constricted; posterior margin of incisive foramen farther from
+      premolars; p4 with four, instead of three, counterfolds; lower
+      molars with three instead of two counterfolds. From _P. g.
+      leioprimna_, _nesiotes_ differs in: Incisive foramen with parallel
+      borders instead of oval; p4 with four instead of three
+      counterfolds; m3 always with three instead of two counterfolds.
+
+_Remarks._--Dr. E. Snethlage mentions the type as having been collected
+at night in the forest.
+
+      _Specimens examined._--Total number, 8 (MCZ, CNHM, MN), from
+      Brazil, Pará, Tocantins River, Ilha de Manapirí.
+
+
+=Proechimys guyannensis leioprimna= subspecies nova
+
+      _Type locality._--Cametá, left bank of Tocantins River, near its
+      mouth, Cametá, Pará, Brazil. _Type_: Chicago Natural History
+      Museum, no. 19503, adult female; collected on 21 January, 1911, by
+      Dr. Emilia Snethlage; original number, 35.
+
+      _Range._--Known only from type locality but probably extending
+      westward toward Xingú River.
+
+      _Diagnosis._--Aristiforms wide and stiff; general color on upper
+      parts Ochraceous-Orange, incisive foramen moderately long; oval;
+      vomerine sheath complete; all molariform teeth with three
+      counterfolds, except lower, third molar which has only two.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip which is extended as a short
+      filament; total length, 19 to 21 mm; maximum width, 0.8 to 1 mm.
+      _Setiforms on middorsal region_: Whitish basally, gradually
+      blackening toward tip but interrupted by Ochraceous-Orange,
+      subapical zone 2 to 3 mm long; total length, 17 to 20 mm; maximum
+      width 0.1 mm. _Setiforms on outer thighs_: Whitish basally,
+      becoming gradually gray and then blackish toward tip but
+      interrupted by Ochraceous-Buff, subapical zone; blackish tip
+      short; total length 13 to 15 mm; maximum width 0.06 mm.
+
+      _Skull._--Of medium size; rostrum relatively short; nasals with
+      posterior borders rounded; postorbital ridges extending across
+      anterior fourth of parietals; zygomatic arches moderately strong;
+      postorbital process of zygoma involving both jugal and squamosal;
+      incisive foramen of medium length (4 to 5 mm) and narrow (about
+      2.5 mm), oval and extending caudad to a plane approximately 2 mm
+      anterior to premolars; vomerine sheath complete, with premaxillae
+      forming approximately anterior 3/4 of sheath; maxillary part of
+      sheath short but well-developed; mesopterygoid fossa extending
+      forward as far as centers of third molars; bullae of medium size
+      but well-inflated.
+
+      _Teeth._--Upper molariform teeth with three counterfolds. Lower
+      molariform teeth with three counterfolds, except third molar which
+      has only two.
+
+      _Comparison._--From _P. g. oris_, _leioprimna_ differs in:
+      conspicuously wider aristiforms; shorter and narrower incisive
+      foramen; lower molariform teeth with three counterfolds (except m3
+      with only two), instead of lower molars with only two
+      counterfolds. Differences from _P. g. nesiotes_ are given in the
+      account of that subspecies.
+
+_Remarks._--The paratype was collected in an "igarapé," depression
+usually invaded by the river waters; the paratype, collected on 18
+January, 1911, had two large embryos.
+
+      _Specimens examined._--Total number, 4 (2 CNHM, 2 AMNH), from
+      Brazil, Pará, Cametá.
+
+
+=Proechimys guyannensis oris= Thomas
+
+      _Proechimys oris_ Thomas, September, 1904, Ann. Mag. Nat. Hist., 14
+      (ser. 7): 195; Thomas, 1905, Ann. Mag. Nat. Hist., 15 (ser. 7):587;
+      Thomas, 1912, Ann. Mag. Nat. Hist., 9 (ser. 8):89; Tate, 1935,
+      Bull. Amer. Mus. Nat. Hist., 68:400; Osgood, 1944, Zool. Ser. Field
+      Mus. Nat. Hist., 29:199.
+
+      _Proechimys cayennensis oris_ Ellerman, 1940, The families and
+      genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121.
+
+      _Type locality._--Igarapé-assú, E. F. B., near Belem, Igarapé-assú,
+      Pará, Brazil. _Type_: British Museum (Nat. Hist.), no. 4.7.4.78,
+      old male; collected on 6 March, 1904, by Alphonse Robert; original
+      number, 1818.
+
+      _Range._--Probably most of the region on south bank of Amazon
+      River, between Tocantins (west) and Gurupí River (south).
+
+      _Diagnosis._--Aristiforms narrow but somewhat stiff; color on
+      upper parts Ochraceous-Orange; incisive foramen long and wide,
+      conspicuously constricted posteriorly; posterior margin of incisive
+      foramen close to plane of premolars; vomerine sheath complete but
+      maxillary part threadlike; upper molariform teeth and lower
+      premolar with three counterfolds; lower molars with only two
+      counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip, which is extended as a filament;
+      total length, 16 to 17 mm; maximum width, 0.6 to 0.7 mm.
+      _Setiforms on middorsal region_: Gray basally, gradually becoming
+      blackish toward tip but interrupted by Ochraceous-Orange,
+      subapical zone 2 to 4 mm long; total length, 18 to 20 mm; maximum
+      width 0.06 mm. _Setiforms on outer thighs_: Whitish basally,
+      gradually becoming blackish toward tip but interrupted by
+      Ochraceous-Buff, subapical zone; total length, 15 to 16 mm;
+      maximum width, 0.04 mm.
+
+      _Skull._--Of medium size; supraorbital ridges well developed and
+      extending across anterior fifth of parietals; zygomatic arches
+      strong; jugal with masseteric fossa deep and with well-developed
+      posterior process; postorbital zygomatic process involving mostly
+      squamosal; incisive foramen long (6 to 7 mm), widest anteriorly
+      (2.5 to 3.2 mm); but narrowing posteriorly to less than 1 mm and
+      extending caudad almost to plane of premolars; vomerine sheath
+      complete but maxillary part delicate and threadlike; mesopterygoid
+      fossa extending forward as far as third molars or posterior parts
+      of second molars; bullae large and inflated.
+
+      _Teeth._--Each upper molariform tooth with three counterfolds. In
+      lower jaw, premolar with three, and molars with only two,
+      counterfolds.
+
+      _Comparisons._--Differences from the subspecies with adjoining
+      ranges are given in the accounts of those subspecies.
+
+_Remarks._--Thomas (1912:89) extended the known range of the subspecies
+to Faro, on the Jamundá River, on the left bank of the Amazon, and to
+Boim, on the Tapajoz River, as well as to Benevides, E. F. Braganca,
+near Belem. It seems to me that the specimens from Faro should be
+referred provisionally to _Proechimys guyannensis hyleae_; the specimens
+from Boim are "more brightly rufous" (Thomas, _loc. cit._) and could be
+referred to Allen's _P. boimensis_, described in 1914, but _P.
+guyannensis hyleae_ probably lives in the same place and only an
+examination of the specimens, which I have not seen, would permit of
+certainly allocating the specimens to their correct species. The
+specimens from Benevides are more certainly _P. g. oris_.
+
+E. Snethlage collected one specimen in a garden (Providencia, E. F. B.).
+However, according to the personnel of the Brazilian Health Service, the
+animals are strictly forest dwellers although they do make excursions
+into more open places.
+
+      _Specimens examined._--Total number, 3, from Brazil, Pará, as
+      follows: Providencia, E. F. B., approximately 15 kilometers east
+      from Belem, 1 (CNHM); Tanaquará, near Belem, 1 (MN); Rio Guamá,
+      near Belem, 1 (AMNH).
+
+      _Additional record._--Brazil, Pará, Benevides, E. F. B.,
+      approximately 100 kilometers north-east of Belem (Thomas,
+      1912:89).
+
+
+=Proechimys guyannensis arescens= Osgood
+
+      _Proechimys cayennensis arescens_ Osgood, 12 July 1944, Zool. Ser.
+      Field Mus. Nat. Hist., 29(13): 198.
+
+      _Type locality._--Fazenda Inhuma, below Santa Filomena, upper Rio
+      Parnaiba, _Vitoria do Alto Parnaiba_, Maranhão, Brazil. _Type_:
+      Chicago Natural History Museum, no. 26441, adult male; collected on
+      5 August, 1925, by Heinrich E. Snethlage.
+
+      _Range._--Region including the valleys of the Turí-assú and
+      Parnaiba rivers, Maranhão, Brazil.
+
+      _Diagnosis._--Aristiforms moderately wide and not conspicuously
+      stiff; general color of upper parts near (15'a) Ochraceous-Orange;
+      incisive foramen long and wide; vomerine sheath complete or
+      incomplete; upper molariform teeth and lower premolar with three
+      counterfolds; lower molars with only two.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually blackening toward tip; total length, 19 to 21 mm;
+      maximum width, 0.7 mm. _Setiforms on middorsal region_: Whitish
+      basally or on basal half, gradually becoming gray and then
+      blackish toward tip, but interrupted by long (5 to 6 mm) subapical
+      zone near (15'_a_) Ochraceous-Orange; total length, 15 to 16 mm;
+      maximum width 0.05 mm. _Setiforms on outer thighs_: Whitish on
+      basal half, gradually becoming gray and then blackish toward tip
+      but interrupted by Ochraceous-Buff, subapical zone; tip sometimes
+      not conspicuously darker than subapical zone; total length 18 to
+      25 mm; maximum width, 0.03 mm.
+
+      _Skull._--Medium in size, not elongated; nasals pointed
+      posteriorly; supraorbital ridges strong and thick, extending
+      caudad across anterior third of parietals; zygomatic arches
+      strong; postorbital process of zygoma involving only squamosal;
+      incisive foramen 5 by 2.7 mm, oval and extending caudad to plane
+      approximately 2 mm anterior to premolars; posterior margins of
+      incisive foramen not forming a ridge; vomerine sheath complete and
+      with maxillary part slender and threadlike, or incomplete, in
+      which event, maxillary part not extended enough to join
+      premaxillary process; mesopterygoid fossa extending forward
+      as far as centers of third molars; bulla large and more or less
+      triangular in its peripheral outline.
+
+      _Teeth._--Upper molariform teeth with three counterfolds each.
+      Lower premolar with three counterfolds; lower molars with two
+      counterfolds.
+
+      _Comparisons._--From _P. g. oris_, _arescens_ differs in: Color of
+      upper parts lighter and more uniform; incisive foramen oval
+      instead of conspicuously constricted posteriorly; posterior margin
+      of incisive foramen farther from premolars.
+
+_Remarks._--One specimen from Turí-assú (MN) has been identified by O.
+Thomas as "_P. oris_" (his own handwriting is on the label) and the
+subspecies is really closely related to _oris_.
+
+      _Specimens examined._--Total number, 3, from Brazil, Maranhão, as
+      follows: _Vitoria do Alto Parnaiba_, Fazenda Inhuma (below Santa
+      Filomena), 2 (CNHM); Alto da Alegria, Turí-assú, 1 (MN).
+
+
+=Proechimys guyannensis riparum= subspecies nova
+
+      _Type locality._--Manaus, _Manaus_, Amazonas, Brazil. _Type_:
+      American Museum of Natural History, no. 143018, adult female;
+      collected 6 March, 1943.
+
+      _Range._--Known only from type locality but probably extending
+      northward and eastward.
+
+      _Diagnosis._--Aristiforms wide and stiff; upper parts
+      Ochraceous-Tawny; incisive foramen short, wide, and oval; vomerine
+      sheath incomplete; upper molariform teeth and lower premolar with
+      three counterfolds; lower molars with only two counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally
+      gradually blackening toward tip; total length, 18 to 20 mm;
+      maximum width, 0.9 mm. _Setiforms on middorsal region_: Whitish
+      basally, gradually blackening toward tip but interrupted by 2 mm
+      long, Ochraceous-Tawny, subapical zone; total length 20 to 22 mm;
+      maximum width, 0.04 mm. Some are whitish basally and gradually
+      become black toward tip with no subapical zone. _Setiforms on
+      outer thighs_: Whitish basally, gradually becoming gray and then
+      blackish toward tip but interrupted by Ochraceous-Buff, subapical
+      zone 3 to 4 mm long; tip not conspicuously dark; total length, 17
+      to 19 mm; maximum width, 0.03 mm.
+
+      _Skull._--Of medium size and slender; rostrum slender; nasals
+      rounded posteriorly; supraorbital ridges well developed and barely
+      extended onto anteriormost part of parietals; zygomatic arches
+      slender; infraorbital foramen with well-developed groove for nerve
+      transmission; postorbital process of zygoma almost obsolete and
+      involving mostly squamosal; incisive foramen short and wide (4.5 ×
+      3.3 mm), oval and with posterior margins raised to form ridges
+      which extend toward premolars; posterior margin of incisive
+      foramen approximately 2.5 mm anterior to premolars; vomerine
+      sheath incomplete, with only short, premaxillary part;
+      mesopterygoid fossa extending forward as far as anterior
+      parts of third molars; bullae large and inflated, with more or
+      less triangular outline.
+
+      _Teeth._--Crown length of well worn P4-M3, 6.8 mm; upper
+      molariform teeth with three counterfolds each. Lower premolar
+      with three counterfolds; lower molars with two counterfolds.
+
+[Illustration: FIG. 98. Map showing the geographic ranges of the
+subspecies of _Proechimys guyannensis_ in Brazil.]
+
+      _Comparisons._--From _P. g. oris_ and _P. g. hyleae_, _riparum_
+      differs in: Shorter and wider incisive foramen; vomerine sheath
+      incomplete, instead of sometimes incomplete. From _P. g. oris_,
+      _riparum_ differs in: Upper parts Ochraceous-Tawny instead of
+      Ochraceous-Orange; aristiforms conspicuously wider. From _P. g.
+      hyleae_, _riparum_ differs in: Aristiforms narrower; upper parts
+      Ochraceous-Tawny instead of Tawny; lower premolars with three,
+      instead of four, counterfolds; lower molars with two, instead of
+      three, counterfolds.
+
+      _Specimens examined._--Type only.
+
+
+=Proechimys guyannensis arabupu= subspecies nova
+
+      _Type locality._--Arabupu, Mount Roraima, _Bõa Vista_, Territ. Rio
+      Branco; about 1540 meters altitude. _Type_: American Museum of
+      Natural History, no. 75816, adult male; collected by Dr. G. H. H.
+      Tate on 30 December, 1927; original number, 4716.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms conspicuously wide and stiff; color on
+      upper parts dark, near (15'_j_) Ochraceous-Tawny; incisive foramen
+      widest in anterior third; vomerine sheath complete, sometimes
+      incomplete; upper molariform teeth and lower premolar with three
+      counterfolds; lower molars with two counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Whitish basally,
+      gradually blackening toward tip; total length, 19 to 22 mm;
+      maximum width, 1.1 mm. _Setiforms on middorsal region_: Gray
+      basally, gradually blackening toward tip but interrupted by dark
+      (15'j) Ochraceous-Tawny, subapical zone 3 mm long; some completely
+      blackish on distal parts; total length, 20 to 23 mm; maximum
+      width, 0.07. _Setiforms on outer thighs_: Whitish basally,
+      gradually blackening toward tip but interrupted by Ochraceous-Buff
+      or Light Ochraceous-Buff, subapical zone; total length, 20 to 23
+      mm; maximum width, 0.07 mm.
+
+      _Skull._--Size medium; nasals pointed posteriorly; supraorbital
+      ridges prominent and slightly extended caudad onto anterior half
+      of parietals; groove for transmission of nerve in infraorbital
+      foramen weakly developed; zygomatic arches strong; postorbital
+      process of zygoma involving mostly squamosal; incisive foramen
+      approximately 5.5 × 2.7 mm, widest in anterior third and
+      constricted posteriorly, with posterior margin about 1 mm anterior
+      to plane of premolars; vomerine sheath complete, with premaxillary
+      part expanded and maxillary part notably slender and sometimes
+      lacking; mesopterygoid fossa in some specimens extending forward
+      as far as middle parts of second molars; bullae large and
+      inflated.
+
+      _Teeth._--Upper molariform teeth with three counterfolds each.
+      Lower premolar with three counterfolds; molars with only two.
+
+      _Comparisons._--From _P. g. warreni_, _arabupu_ differs in:
+      Narrower aristiforms; narrower incisive foramen; lower premolar
+      with three instead of four counterfolds; lower molars with two,
+      instead of three, counterfolds. From _P. g. oris_, _arabupu_
+      differs in: Aristiforms wider; posterior margin of incisive
+      foramen farther from plane of premolars; upper parts dark (15'_j_)
+      Ochraceous-Tawny, instead of Ochraceous-Orange.
+
+_Remarks._--The sample is fairly uniform.
+
+      _Specimens examined._--Total number, 6 (AMNH), from Brazil,
+      Territorio do Rio Branco, Bõa Vista, Mount Roraima, Arabupu;
+      approximately 1540 m. altitude.
+
+
+Subgenus =TRINOMYS= Thomas
+
+      _Genotype._--_Echimys albispinus_ Is. Geoffroy Saint-Hilaire, 1838;
+      by original designation.
+
+      _Trinomys_ Thomas, July 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):140
+      (orig. descr.); Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):401; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:115.
+
+[Illustration: FIG. 99. Map showing the geographic ranges of the
+subspecies of three species of the subgenus _Trinomys_.]
+
+      _General characters._--Pelage of upper parts with lanceolate and,
+      sometimes, clavate aristiforms extending over most of rump and onto
+      thighs; tail 86 to 103 per cent of length of head and body; tail
+      sometimes white-tipped and sometimes penicillate; skull small, with
+      ridges moderately developed; supraorbital ridges involving no part
+      of parietals; infraorbital foramen with no separate groove for
+      transmission of nerve; mesopterygoid fossa extending forward to
+      level of second or first molars; incisors opisthodont, orthodont or
+      proodont; molariform teeth, in occlusal view, with main fold large
+      and usually reaching opposite wall; no counterfold anterior to main
+      fold in upper molariform teeth and usually no counterfold posterior
+      to main fold in lower molariform teeth; premolars larger than first
+      molars, first molars larger than second molars and second molars
+      larger than third molars; four molariform teeth of nearly equal
+      size in some animals.
+
+      Thomas (1921:140) erected the subgenus _Trinomys_, including in it
+      the species _albispinus_ and _setosus_ and stated that "the primary
+      distinction between these [_Trinomys_ and _Proechimys_] lies in the
+      number of laminae present in the cheekteeth--four in _Proechimys_,
+      three in _Trinomys_." The distinction is valueless as a subgeneric
+      character, not only because the character is not constant in the
+      species in the subgenus but also because there is subspecific
+      variation in number of laminae in the cheekteeth. _Proechimys
+      albispinus_, however, shares with three other species common
+      characters, as listed above, and the name _Trinomys_ will,
+      therefore, apply to this group of species, since _Proechimys
+      albispinus_ is the genotype.
+
+
+=Proechimys dimidiatus= (Günther)
+
+      _Echimys dimidiatus_ Günther, 1 April 1877, Proc. Zool. Soc.
+      London, 1876(4):747.
+
+      _Proechimys dimidiatus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):264; Ribeiro, 1905, Arch. Mus. Nac. Rio de Janeiro, 13:187;
+      Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141; Tate, 1935,
+      Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The
+      families and genera of living rodents, Brit. Mus. (Nat. Hist.),
+      1:122.
+
+      _Type locality._--Unknown; probably southwestern Rio de Janeiro,
+      Brazil (see Remarks). _Type_: British Museum (Nat. Hist.), no.
+      51.7.21.24; presented by Lord Derby.
+
+      _Range._--Rio de Janeiro, from the southern limit of the state
+      northward to and including the Distrito Federal.
+
+      _General characters._--Size large; tail averaging 80 per cent of
+      head and body; aristiforms narrow and soft (0.4 to 0.5 mm wide),
+      imparting a non-spiny character to the pelage; general color of
+      upper parts Ochraceous-Buff, finely lined with blackish brown,
+      gradually becoming lighter on sides; ventral surface of body and
+      inner sides of legs white; feet dorsally white but with a
+      sepia-colored stripe along outer margin; tail brownish-black above
+      and white below, but white sometimes extended to upper side in
+      distal part; skull broad with no conspicuous ridges; jugals deep
+      with transverse ridge usually conspicuous; postorbital process of
+      zygoma involving only squamosal; incisive foramen short and wide
+      posteriorly; vomerine sheath complete in 95 per cent of specimens
+      and with maxillary part thick; posterior palatine foramina at
+      plane of first molars or slightly anterior to them; bullae
+      moderately developed; in juvenal specimens, each upper molariform
+      tooth with three counterfolds, but posteriormost counterfold
+      small; in adult specimens, posteriormost counterfold
+      disappearing in 50 per cent of fourth premolars and first molars,
+      in 20 per cent of second molars, and in 15 per cent of third
+      molars; lower molariform teeth with two counterfolds in almost
+      every juvenal specimen, this number, in adult animals, decreasing
+      in m3 to one in 20 per cent of specimens but rarely being reduced
+      in other teeth.
+
+      _General characters._--Aristiforms soft and narrow, ranging from 15
+      to 19 mm in total length and 0.4 to 0.5 mm in maximum width; pelage
+      generally non-spiny and not harsh; length of tail ranging from 20
+      per cent shorter than head and body to as long as, or slightly
+      longer than, head and body; ears rather small (23 to 25 mm).
+
+[Illustration: FIGS. 100-103. _Proechimys dimidiatus_, male, MN no.
+5452, Tijuca. × 1.]
+
+      _Color._--General color of back and sides results from uniform
+      mixture of black distal parts of aristiforms with Ochraceous-Buff
+      of subapical zone of setiforms. Dorsally, from nose caudad to rump,
+      mixture appears brownish-black, lined with Ochraceous-Buff; toward
+      sides, amount of Ochraceous-Buff gradually increases and resultant
+      color is much lighter brown than on back. On outer parts of arms
+      and legs, color turns gradually to sepia toward distal parts and
+      finally to uniform sepia on wrists and ankles, this color extending
+      to outer dorsal parts of hands and feet; on ankles, sepia forms
+      complete ring, as usual in the genus. Tail blackish-brown on upper
+      parts, this stripe gradually tapering toward tip where dark brown
+      hairs form small pencil; white of under side of tail sometimes seen
+      also entirely around distal part, short of tip which remains dark
+      brown. Ventral surfaces wholly white, from upper lips caudad
+      including inner surfaces of legs.
+
+      _Hairs._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip that has long, fine filament;
+      total length 16 to 19 mm; maximum width 0.5 mm. On outer thigh
+      whitish basally, gradually blackening toward tip; some with
+      Ochraceous-Buff, subapical zone; total length 13 to
+      15 mm; maximum width 0.25 mm. _Setiforms on middorsal region_:
+      Whitish on basal half, gradually blackening toward tip, but
+      interrupted by Ochraceous-Buff, subapical zone; some with Light
+      Ochraceous-Buff, subapical zone and short, blackish zone on tip;
+      total length 12 to 14 mm; maximum width 0.02 mm. _Setiforms on
+      outer thighs_: Whitish on basal half, then gradually becoming gray
+      on middle part and finally Light Ochraceous-Buff on distal third,
+      or with tip blackish and Ochraceous-Buff, subapical zone.
+
+      _Skull._--Elongate and broad with no conspicuous crests; rostrum
+      rather stout; jugals deep with transverse crest usually
+      well-developed; zygomatic postorbital process conspicuous and
+      formed entirely of squamosal; incisive foramen short and wide
+      posteriorly; vomerine sheath complete in great majority of
+      specimens, its maxillary part wide and strong; posterior palatine
+      foramina on plane with front of M1 or slightly farther forward;
+      bullae rather small and elongate.
+
+      _Teeth._--P4 with three secondary folds in all juvenal specimens,
+      but posteriormost fold small and disappearing in 50 per cent of
+      adult specimens; M1 with 3 outer folds in juveniles and also
+      disappearing in 50 per cent of adults; M2 with three outer folds
+      in juveniles, but only 20 per cent remaining in adults; M3 with 3
+      outer folds in 50 per cent of juveniles, decreasing to 15 per cent
+      in adults. Lower molariform teeth: p4 with 2 secondary folds; m1
+      with 2 secondary folds in 90 per cent of adults and in all
+      juveniles; m2 with 2 secondary folds in 98 per cent of adults and
+      in all juveniles; m3 with 2 secondary folds in 81 per cent of
+      adults, remaining percentage with only one counterfold, and with 2
+      secondary folds in all juveniles.
+
+_Remarks._--Samples studied of _P. dimidiatus_ are notably uniform
+throughout the geographic range of the species. The few biotypes
+detected seemed unworthy of subspecific rank.
+
+In discussing the type locality of the species, Thomas (1921:141)
+states: "We know that its donor did obtain a number of specimens from
+Rio Janeiro, and the skull agrees so closely with those of two examples
+from Itatiaia, near to the Rio-Minas frontier, collected and presented
+by Prof. J. P. Hill, that I have no hesitation in referring the latter
+to Günther's species."
+
+      _Specimens examined._--Total number, 211 (MN), from Brazil as
+      follows: Rio de Janeiro; _Parati_, Pedra Branca (400 m.), 113;
+      _Mangaratiba_, Fazenda do Rubião (750 m.), 3; Fazenda do Tenente
+      (700 m.), 4; Fazenda da Lapa (450 m.), 13; _Teresópolis_, Fazenda
+      Guinle (960 m.), 61; _Nova Iguassú_, Barro Branco (20 m.), 16;
+      Distrito Federal, Tijuca, 1.
+
+      _Additional records._--Rio de Janeiro, Itatiaia (Thomas,
+      1921:141); Rio de Janeiro, Zona da mata, Mont-Serrat, Serra do
+      Itatiaia (Ribeiro, 1905:187).
+
+
+=Proechimys iheringi= Thomas
+
+      _General characters._--Size large; tail long; aristiforms generally
+      wide and stiff; general color on upper parts and sides a
+      combination of blackish from tips of aristiforms with cinnamon
+      ground color from subapical zones of setiforms; darker band on
+      middorsal line; differentiated light-colored aristiforms
+      conspicuous on outer sides of thighs and rump; usually rufous tint
+      on neck and postauricular region; underparts white; tail with white
+      tip, usually accentuated by white brush; feet white on dorsal
+      surface; hind feet slightly darker on outer sides; skull elongate
+      and smooth; jugals wide dorso-ventrally; incisive foramen elongate;
+      upper molariform teeth usually with one to five counterfolds, number
+      varying with subspecies; lower premolar always with two counterfolds
+      and lower molars always with one or two counterfolds.
+
+_Remarks._--As a whole, the samples of the populations of the species do
+not afford a satisfactory record of the distribution; my concept of the
+group may be changed when further collections are made in localities
+geographically intermediate between those from which specimens now are
+known. If some of the forms prove to be physiologically isolated, they
+may deserve treatment as full species according to the conventional
+standards of systematic zoology. _P. panema_, for example, does not seem
+to be geographically isolated from _P. gratiosus_. _P. denigratus_, at
+the northernmost known occurrence of the species, actually represents a
+striking jump in the cline, although collections from intermediate
+regions may provide intermediate structural stages. Further collecting
+may also prove that the southern form, _P. iheringi iheringi_, is
+completely isolated from the rest of the group. However, these samples
+are certainly more related to each other than any one of them is to that
+of the other species found in the same range, namely _P. dimidiatus_,
+and all the forms in question, therefore, seem best arranged as
+subspecies of one full species. A clinal variation certainly exists
+among these forms and the most striking differences correspond to larger
+geographical distances.
+
+[Illustration: FIG. 104. _Proechimys iheringi iheringi_, female, MN no.
+6453, Ilha de São Sebastião. × 1.]
+
+[Illustration: FIG. 105. _Proechimys iheringi bonafidei_, male, MN no.
+6183, Fazenda Bõa Fé. Type. × 1.]
+
+[Illustration: FIG. 106. _Proechimys iheringi gratiosus_, male, MN no.
+4024, Floresta da Caixa Dagua. Type. × 1.]
+
+[Illustration: FIG. 107. _Proechimys iheringi panema_, female, MN no.
+8288, Campinho. Type. × 1.]
+
+[Illustration: FIG. 108. _Proechimys iheringi denigratus_, male, MN no.
+8500, Mata do Ribeirão da Fortuna. Type. × 1.]
+
+[Illustration: FIG. 109. _Proechimys iheringi paratus_, female, MN no.
+4012, Floresta da Capela de São Braz. Type. × 1.]
+
+[Illustration: FIG. 110. _Proechimys iheringi iheringi_, female, MN no.
+6453, Ilha de São Sebastião. × 1.]
+
+[Illustration: FIG. 111. _Proechimys iheringi bonafidei_, male, MN no.
+6183, Fazenda Bõa Fé. Type. × 1.]
+
+[Illustration: FIG. 112. _Proechimys iheringi gratiosus_, male, MN no.
+4024, Floresta da Caixa Dagua. Type. × 1.]
+
+[Illustration: FIG. 113. _Proechimys iheringi panema_, female, MN no.
+8288, Campinho. Type. × 1.]
+
+[Illustration: FIG. 114. _Proechimys iheringi denigratus_, male, MN no.
+8500, Mata do Ribeirão da Fortuna. Type. × 1.]
+
+[Illustration: FIG. 115. _Proechimys iheringi paratus_, female, MN no.
+4012, Floresta da Capela de São Braz. Type. × 1.]
+
+[Illustration: FIGS. 116, 117. _Proechimys iheringi iheringi_, female,
+MN no. 6453, Ilha de São Sebastião. × 1.]
+
+[Illustration: FIGS. 118, 119. _Proechimys iheringi bonafidei_, male, MN
+no. 6183, Fazenda Bõa Fé. Type. × 1.]
+
+[Illustration: FIGS. 120, 121. _Proechimys iheringi gratiosus_, male, MN
+no. 4024, Floresta da Caixa Dagua. Type. × 1.]
+
+[Illustration: FIGS. 122, 123. _Proechimys iheringi panema_, female, MN
+no. 8288, Campinho. Type. × 1.]
+
+[Illustration: FIGS. 124, 125. _Proechimys iheringi denigratus_, male,
+MN no. 8500, Mata do Ribeirão da Fortuna. Type. × 1.]
+
+[Illustration: FIGS. 126, 127. _Proechimys iheringi paratus_, female, MN
+no. 4012, Floresta da Capela de São Braz. Type. × 1.]
+
+
+=Proechimys iheringi iheringi= Thomas
+
+      _Proechimys iheringi_ Thomas, August, 1911, Ann. Mag. Nat. Hist., 8
+      (ser. 8):252 (orig. descr.); Thomas, 1921, Ann. Mag. Nat. Hist., 8
+      (ser. 9):141; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400;
+      Ellerman, 1940, The families and genera of living rodents, Brit.
+      Mus. (Nat. Hist.), 1:122.
+
+      _Type locality._--Island of São Sebastião (off São Paulo), Formosa,
+      São Paulo, Brazil. _Type_: British Museum (Nat. Hist.), no.
+      2.8.25.5, adult male, presented by the São Paulo Museum.
+
+      _Range._--Littoral and islands of São Paulo and Rio de Janeiro.
+
+      _Diagnosis._--Aristiforms narrow; tail shorter than head and body;
+      setiforms Cinnamon-Buff; incisive foramen short; vomerine sheath
+      complete; upper molariform teeth with two or three counterfolds;
+      lower molariform teeth with two counterfolds, rarely one in m3.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length 18 to 23 mm; maximum
+      width, 0.6 mm. _Aristiforms on outer thighs_: Gray basally,
+      blackening distally toward tip; some differentiated with
+      Cinnamon-Buff tip. _Setiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip but interrupted by a
+      Cinnamon-Buff, subapical zone 3 mm long; total length, 16 to 20
+      mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Gray
+      basally, gradually blackening toward tip but interrupted by
+      Cinnamon-Buff, subapical zone or with Cinnamon-Buff continuous to
+      tip.
+
+      _Skull._--Slender; bullae small and well inflated; jugal
+      dorso-ventrally wide with transverse ridge inconspicuous; incisive
+      foramen short, 3.5 × 2.5 mm; vomerine sheath complete;
+      mesopterygoid fossa extending forward as far as middle parts of
+      second molars; postorbital process of zygoma small, formed by both
+      jugal and squamosal; posterior palatine foramina at plane of
+      premolars; interorbital breadth narrow.
+
+      _Teeth._--Upper molariform teeth with two or three counterfolds
+      (when unworn usually three and rarely four); sometimes only one
+      counterfold in M3 and sometimes counterfolds fused in molars.
+      Lower molariform teeth with two counterfolds, rarely one in m3.
+
+      _Comparisons._--From _P. i. bonafidei_ and _P. i. gratiosus_,
+      _iheringi_ differs in: Incisive foramen shorter; vomerine sheath
+      complete, instead of usually incomplete; setiforms Cinnamon-Buff,
+      instead of Ochraceous-Buff; upper molariform teeth with two or
+      three separate counterfolds, instead of having counterfolds fused
+      or reduced to one or two; aristiforms narrower in _iheringi_ than
+      in _bonafidei_.
+
+      _Specimens examined._--Total number, 25, from Brazil, as follows:
+      São Paulo, _Formosa_, Ilha de São Sebastião, 9 (DZ 6, MN 2, MCZ 1);
+      São Paulo, _Mogi das Cruzes_, Alto da Serra, alt. 900 m., 2 (DZ);
+      São Paulo, _Ubatuba_, alt. 10 m., 4 (2 DZ, 2 MN); Rio de Janeiro,
+      _Angra dos Reis_, 2 (MN); Rio de Janeiro, _Angra dos Reis_, Ilha
+      Grande, 7 (5 DZ, 1 MCZ, 1 MN).
+
+
+=Proechimys iheringi bonafidei= subspecies nova
+
+      _Type locality._--Fazenda Bõa Fé, _Teresópolis_, Rio de Janeiro,
+      Brazil; alt. 850 meters. _Type_: Museu Nacional, no. 6183, adult
+      male; collected on 18 August, 1942, by G. Pereira; SEPFA no. M
+      14663.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms wide and stiff; tail shorter than head
+      and body; setiforms Ochraceous-Buff; incisive foramen long;
+      vomerine sheath incomplete, or rarely complete; molariform teeth
+      with two counterfolds usually fused.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 22 to 26 mm;
+      maximum width, 0.8 mm. _Aristiforms on outer thighs_: Gray
+      basally, gradually blackening toward tip but interrupted by
+      Ochraceous-Buff subapical zone; some Ochraceous-Buff to tip; total
+      length, 18 to 20 mm; maximum width, 0.7 mm. _Setiforms on
+      middorsal region_: Gray basally, gradually blackening toward tip
+      but interrupted by Ochraceous-Buff, subapical zone; total length,
+      17 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer thighs_:
+      Gray basally, gradually blackening toward tip but interrupted by
+      Ochraceous-Buff, subapical zone; only a short blackened tip.
+
+      _Skull._--Large, with elongate rostrum; bullae large and well
+      inflated; jugals with transverse ridge inconspicuous; postorbital
+      process of zygoma small, formed mostly by squamosal; incisive
+      foramen elongated (5.5 × 2.5 mm); vomerine sheath incomplete or,
+      if complete, with maxillary part thin and delicate; posterior
+      palatine foramen at plane of first molars; mesopterygoid fossa
+      extending forward as far as middle parts of second molars.
+
+      _Teeth._--Upper molariform teeth with two counterfolds; these
+      completely separated in 3 of 16 specimens; two counterfolds
+      coalesced in all three molars in 6 specimens; counterfolds
+      coalesced in only two molars in 3 specimens; counterfolds
+      coalesced in only one molar in 4 specimens. Lower molariform teeth
+      with two counterfolds which are completely separated in 13 of 16
+      specimens; counterfolds coalesced in only one molar in 2
+      specimens; counterfolds coalesced in all three molars in one
+      specimen.
+
+      _Comparisons._--From _P. i. gratiosus_, _bonafidei_ differs in:
+      Aristiforms wider; tail shorter; molariform teeth with two
+      counterfolds instead of one or two. Differences from _P. i.
+      iheringi_ are given in the account of that subspecies.
+
+_Remarks._--Of females with embryos two were captured in April and one
+in September. The embryos number 2, 1, 2. Young were captured mostly in
+April, but two were taken in July. Male gonads seemed to be most active
+in March, April and September. The animals lived in a second growth
+forest, approaching the climax. The rainfall was more than 1600 mm
+annually, and the mean annual temperature was 18.5° centigrade.
+
+      _Specimens examined._--Total number, 18 (MN), from Brazil, Rio de
+      Janeiro, _Teresópolis_, Fazenda Bõa Fé.
+
+
+=Proechimys iheringi gratiosus= subspecies nova
+
+      _Type locality._--Floresta da Caixa Dagua, _Santa Teresa_, Espirito
+      Santo, Brazil; altitude 750 meters. _Type_: Museu Nacional, no.
+      4024, adult male; collected on 25 May, 1940, by C. Lako; SEPFA no.
+      M 6911.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms narrow; tail of same length as head and
+      body; setiforms Ochraceous-Buff; incisive foramen long; vomerine
+      sheath usually incomplete; upper molariform teeth with one or two
+      counterfolds; lower molariform teeth with two counterfolds, except
+      that m3 usually has only one.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 21 to 27 mm; maximum
+      width, 0.6 mm. _Aristiforms on outer thighs_: Gray basally,
+      gradually blackening toward middle, and Ochraceous-Buff on distal
+      half; total length, 18 to 21 mm; maximum width, 0.5 mm. _Setiforms
+      on middorsal region_: Gray basally, gradually blackening toward tip
+      but interrupted by short, Ochraceous-Buff, subapical zone; total
+      length, 18 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer
+      thighs_: Gray basally, gradually blackening toward middle, and
+      distal part Ochraceous-Buff or with only tip blackened; total
+      length, 14 to 16 mm; maximum width, 0.05 mm.
+
+      _Skull._--Slender; bullae small but well-inflated; upper edge of
+      jugals deeply concave; transverse ridge of jugals conspicuous;
+      postorbital process of zygoma small, involving only squamosal;
+      incisive foramen elongate (5 x 2.5 mm); vomerine sheath almost
+      always incomplete, and maxillary part lacking or, when present,
+      slender; mesopterygoid fossa extending forward as far as middle of
+      second molars; posterior palatine foramina at plane of front
+      border of first molars or slightly anterior thereto.
+
+      _Teeth._--Upper molariform teeth with two counterfolds in 10 of 16
+      specimens and only one in remainder; these folds commonly
+      coalesced; M3 with only one counterfold in 6 specimens, and 2
+      counterfolds in remainder. Lower molariform teeth with two
+      counterfolds in 6 specimens and in 10 of them m3 has only one
+      counterfold.
+
+      _Comparisons._--From _P. i. panema_, _gratiosus_ differs in: Lower
+      molariform teeth with only one counterfold in smaller percentage
+      of specimens; incisive foramen shorter; aristiforms narrower;
+      setiforms Ochraceous-Buff instead of Cinnamon. Differences from
+      _iheringi_ and _paratus_ are given in the accounts of those
+      subspecies.
+
+_Remarks._--All the animals were captured in climax forest.
+
+      _Specimens examined._--Total number, 16 (MN), from Brazil, Espirito
+      Santo, _Santa Teresa_, Floresta da Caixa Dagua, altitude 750
+      meters.
+
+
+=Proechimys iheringi panema= subspecies nova
+
+      _Type locality._--Campinho, _Colatina_, Espirito Santo, Brazil;
+      altitude 500 meters. _Type_: Museu Nacional, no. 8288, adult
+      female; collected on 15 July, 1942, by C. Lako.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms moderately wide; tail of approximately
+      same length as head and body; setiforms Cinnamon; incisive foramen
+      moderately long and narrow; vomerine sheath incomplete; upper
+      molariform teeth with two counterfolds, but m3 most frequently
+      with one.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 21 to 23 mm;
+      maximum width, 0.8 mm. _Aristiforms on outer thighs_: Gray, some
+      gradually blackening toward tip and others with distal part
+      Cinnamon; total length, 17 to 19 mm; maximum width, 0.7 mm.
+      _Setiforms on middorsal region_: Gray, gradually blackening
+      toward tip, but interrupted by Cinnamon, subapical zone; total
+      length, 18 to 20 mm; maximum width, 0.06 mm. _Setiforms on outer
+      thighs_: Gray, gradually blackening toward middle, and Cinnamon on
+      all of distal parts or with tip blackish; total length, 13 to 15
+      mm; maximum width, 0.09 mm.
+
+      _Skull._--Strong, with jugals dorso-ventrally wide; interorbital
+      region and cranium wide; bullae well inflated; transverse ridge of
+      jugals not well-developed; postorbital process of zygoma small and
+      formed only of squamosal; incisive foramen 4.7 × 2.2 mm; vomerine
+      sheath always incomplete, with maxillary part reduced to small
+      process; mesopterygoid fossa extending forward as far as middle of
+      second molars or only slightly short thereof; posterior palatine
+      foramina at plane of front of first molars.
+
+      _Teeth._--All upper molariform teeth with two counterfolds in 4
+      specimens; one having only one counterfold in M3; 3 with
+      counterfolds coalesced in one or two molars. Lower molariform
+      teeth with two counterfolds in one specimen, these counterfolds
+      not coalesced; m3 with one counterfold in 4 specimens and with two
+      in one specimen.
+
+      _Comparisons._--Differences from _P. denigratus_ and _P. i.
+      paratus_ are given in the accounts of those animals.
+
+      _Specimens examined._--Total number, 5 (MN), from Brazil, Espirito
+      Santo, _Colatina_, Campinho; altitude 500 meters.
+
+
+=Proechimys iheringi denigratus= subspecies nova
+
+      _Type locality._--Mata do Ribeirão da Fortuna, 40 kilometers west
+      of Ilheus, _Itabuna_, Bahia, Brazil. _Type_: Museu Nacional, no.
+      8500, adult male; collected 16 March, 1945.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms wide and stiff; tail longer than head
+      and body; setiforms near (15''_a_) Cinnamon; incisive foramen long
+      and narrow; vomerine sheath complete; premolars with two
+      counterfolds, upper molars with one or two, and lower molars with
+      only one.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 20 to 22 mm;
+      maximum width, 1.1 mm. _Aristiforms on outer thighs_: Gray
+      basally, gradually blackening toward tip or with distal part near
+      (15''_a_) Cinnamon; total length, 14 to 16 mm; maximum width, 0.5
+      mm. _Setiforms on middorsal region_: Gray basally, gradually
+      blackening toward tip but interrupted by near (15''_a_) Cinnamon,
+      subapical zone 4 mm wide; total length, 18 to 20 mm; maximum
+      width, 0.05 mm. _Setiforms on outer thighs_: Gray basally,
+      gradually blackening toward tip but interrupted by wide, near
+      (15''_a_) Cinnamon, subapical zone.
+
+      _Skull._--Slender; nasals short; bullae large and well-inflated;
+      jugals with conspicuous transverse ridge; postorbital process of
+      zygoma conspicuous, spiniform and formed almost exclusively by
+      jugal; incisive foramen elongated and narrow (5 × 1.8 mm);
+      vomerine sheath complete and formed almost exclusively by
+      premaxillae; maxillary part of this sheath short and in most
+      specimens the two parts of sheath completed by vomer itself;
+      mesopterygoid fossa extending forward as far as middle of second
+      molars and in some skulls as far as anterior border of second
+      molars; posterior palatine foramina at anterior plane of first
+      molars.
+
+      _Teeth._--Upper molariform teeth: P4 always with two counterfolds;
+      M1 with two counterfolds in 65 per cent of specimens but anterior
+      counterfold poorly developed; rest of specimens with only one
+      counterfold in M1; M2 with two counterfolds in 50 per cent of
+      specimens and only one in remainder; M3 with two counterfolds in
+      only 17 per cent of specimens, and remainder with only one. Lower
+      molariform teeth: p4 always with two counterfolds; molars always
+      with only one counterfold.
+
+      _Comparisons._--From _P. i. panema_, _denigratus_ differs in: Each
+      lower molar with only one, instead of with more than one,
+      counterfold; incisive foramen longer and narrower; vomerine sheath
+      complete instead of incomplete; aristiforms conspicuously wider;
+      tail longer.
+
+_Remarks._--One female (SEPFA no. M 17060) captured on 9 January, 1944,
+gave birth to two females on 26 January, 1944. Each of these young
+measured 177 mm in total length and weighed 27.8 g. On 4 March, 1944,
+their measurements were: head and body, 120,120; tail, 120,130; hind
+foot, 32,33; ear, 21,22; skull:--total length, 36.0,35.0;
+condyloincisive length, 29.0,29.1; zygomatic breadth, 19.1,18.5; length
+of nasals, 12.5,11.6; interorbital constriction, 9.3,8.8; cranial
+breadth, 16.4,16.9; palatilar length, 11.5,10.5; crown length of P4 and
+M1, 4.3,4.3 mm.
+
+The forest where the animals were captured has a high percentage of
+deciduous trees in spite of the heavy rainfall in this region. All of
+the animals were trapped near water. Young were captured from January to
+May. Most animals have a conspicuous Cinnamon patch on the nuchal
+region.
+
+      _Specimens examined._--Total number, 34 (SEPFA 33, MN 1), from
+      Brazil, Bahia, _Itabuna_, Mata do Ribeirão da Fortuna.
+
+
+=Proechimys iheringi paratus= subspecies nova
+
+      _Type locality._--Floresta da Capela de São Braz, _Santa Teresa_,
+      Espirito Santo, Brazil; altitude 630 meters. _Type_: Museu
+      Nacional, no. 4012, adult female; collected on 24 September, 1940,
+      by Dr. H. W. Laemmert; SEPFA no. M 8447.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms wide and stiff; tail 96 per cent of head
+      and body; color on setiform Cinnamon-Buff; incisive foramen short
+      and moderately wide; vomerine sheath complete; all molariform
+      teeth with two counterfolds.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 24 to 26 mm;
+      maximum width, 1.3 mm. _Aristiforms on outer thighs_: Gray
+      basally, gradually blackening toward middle, and distal parts near
+      (15''_c_) Pinkish Cinnamon; total length, 18 to 20 mm; maximum
+      width 0.8 mm. _Setiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip but interrupted by Cinnamon-Buff,
+      subapical zone; total length 14 to 16 mm; maximum width, 0.06 mm.
+
+      _Skull._--Slender; bullae large and well-inflated; jugals with
+      conspicuous, transverse ridge; postorbital process of zygoma
+      moderately developed and involving only squamosal; incisive
+      foramen short and narrow (4.1 × 2.1 mm); vomerine sheath complete,
+      with maxillary part short and thick; mesopterygoid fossa extending
+      forward as far as posterior parts of second molars; posterior
+      palatine foramina at plane of premolars.
+
+[Illustration: FIG. 128. Map showing the geographic ranges of the
+subspecies of _Proechimys iheringi_.]
+
+      _Teeth._--Upper and lower molariform teeth with two counterfolds.
+      Counterfolds coalesced in P4 and M1 of one specimen.
+
+      _Comparisons._--From _P. i. gratiosus_ and _P. i. panema_,
+      _paratus_ differs in: all molariform teeth with two, instead of
+      some with fewer, counterfolds; vomerine sheath complete and thick
+      instead of usually incomplete; incisive foramen shorter and
+      narrower; aristiforms conspicuously wider; setiforms Cinnamon-Buff
+      instead of Ochraceous-Buff and Cinnamon, respectively. Tail 96 per
+      cent of head and body in _paratus_ instead of 100 per cent as in
+      _panema_.
+
+_Remarks._--The animals were captured in climax forest.
+
+      _Specimens examined._--Total number, 3 (MN), from Brazil, Espirito
+      Santo, _Santa Teresa_, Floresta da Capela de São Braz; altitude 630
+      meters.
+
+
+Proechimys setosus (Desmarest)
+
+      _General characters._--Size medium; tail approximately same length
+      as head and body; aristiforms moderately wide; feet rather large;
+      ears of medium size; color on upper parts and sides sepia gradually
+      changing to Ochraceous-Tawny; few differentiated, light-colored
+      aristiforms present on outer thighs and rump; under surface of body
+      and inner sides of legs white; tail with white tip and conspicuous,
+      white pencil; feet white dorsally; skull short and smooth, somewhat
+      flattened in interorbital region; jugals narrow dorso-ventrally;
+      incisive foramen moderately long and notably narrow; vomerine
+      sheath complete and slender; postorbital process of zygoma
+      spinelike and involving mostly jugal; premolars usually with two
+      counterfolds; molars with only one counterfold, rarely two in M1 or
+      in M3.
+
+_Remarks._--The specimens available are undoubtedly faded and,
+therefore, the colors mentioned above for the upper parts and sides may
+not correspond to the colors of unfaded pelages. Desmarest (1817:59)
+describes the color of setosus as similar to that of the "Echimys de
+Cayenne" (_Proechimys guyannensis_) but being more "rousse." Is.
+Geoffroy Saint-Hilaire (1840:52) describes the same animal as being
+"d'un brun roussâtre" on the upper parts.
+
+The _Proechimys_ from Lagoa Santa, Minas Gerais, _"Echimys" elegans_
+Lund, is certainly related to _P. iheringi_ as well as to _P.
+albispinus_. From _P. iheringi_, _elegans_ differs in having a smaller
+skull with shorter rostrum, narrower incisive foramen, and orthodont
+incisors. On the other hand the restricted distribution of the
+aristiforms in the pelage and the white, penicillate tail are points of
+resemblance to _iheringi_. From _P. albispinus_, _elegans_ differs in
+having a less spinous pelage and longer tail with white pencil instead
+of a brown pencil. The skulls, however, are similar, except for the fact
+that _elegans_ does not have proodont incisors as _albispinus_ sometimes
+does. Thomas (1921:141) states, after describing the skull of the type
+of _setosus_, that "Specimens corresponding to this animal have been
+obtained at Lagoa Santa, Minas, by Lund and others, and at Bahia."
+Thomas, however, would not have referred to specimens from "Bahia" as
+being comparable to _elegans_ had they not been different from
+_albispinus_ which he discussed in the same paper. Also, he would not
+have confused "specimens comparable to _elegans_" with a subspecies of
+_P. iheringi_ (_P. i. denigratus_, from southern Bahia) which has
+opisthodont instead of orthodont incisors. Since French collectors sent
+material to Europe at the beginning of the 19th century from (southern?)
+Bahia, possibly _setosus_ came from there.
+
+In the collection of the American Museum of Natural History there is one
+specimen (AMNH no. 16140) of _Proechimys_, included in the so-called
+Maximilian Collection. The characters of this specimen agree closely
+with those of the specimens from Lagoa Santa. The locality of capture of
+specimen no. 16140 is unknown, but it is reasonable to assume that
+Prince Maximilian zu Wied obtained it somewhere along his route of
+travel through southeastern Bahia. Wied (1826:445) mentions
+"_L[oncheres]. myosuros_ Licht." as "am Parahyba, am Peruhype und
+Belmonte," which greatly increases the possibility of its having come
+from southern Bahia. The close similarity to _elegans_ of Wied's
+specimen indicates that the locality of capture possibly was in the
+region of the less humid, low escarpments of southern Bahia.
+
+My conclusion is that Wied's specimen corresponds closely to _setosus_
+and, tentatively, I identify it as such. "_Echimys elegans_," due to the
+relationships mentioned above is here considered to be a subspecies of
+_setosus_.
+
+Among the species described in earlier times, and whose identity was
+never ascertained, _"Echinomys" fuliginosus_ Wagner seems to be
+synonymous with _setosus_. Wagner describes the animal as having a tail
+"apicis versus pilis albidis vestita" and the figure of the cheekteeth
+(1844, pl. 239 D) shows a typical trilaminate condition which occurs
+commonly in _elegans_. Moreover, the tail of _fuliginosus_ is only 9 per
+cent shorter than the head and body and the aristiforms of this
+subspecies are moderately wide.
+
+
+=Proechimys setosus setosus= (Desmarest)
+
+      _Echimys setosus_ Desmarest (Geoffroy's MS), 1817, Nouv. Dict.
+      Hist. Nat. nouv. ed., 10:59 (orig. descr.); Is. Geoffroy
+      Saint-Hilaire, 1838, Comptes Rendus Acad. Sci., Paris, 6(26):886;
+      Is. Geoffroy Saint-Hilaire, 1840, Mag. Zool., Paris, (ser. 2, année
+      2):12, 33, 52; Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):257, 261.
+
+      _Echimys cayennensis_ Pictet, 1841, Mém. Soc. phys. Hist. Nat.,
+      Genève, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334.
+
+      _Echinomys fuliginosus_ Wagner, 1843, Schreber's Säugethiere,
+      suppl. 3:343; Wagner, 1844, Schreber's Säugethiere, suppl. 4, pl.
+      39 D.
+
+      _Proechimys setosus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):264; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141;
+      Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):401; Ellerman,
+      1940, The families and genera of living rodents, Brit. Mus.
+      (Nat. Hist.), 1:122.
+
+      _Proechimys fuliginosus_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+       68(5): 400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _Type locality._--Unknown; see remarks under _P. setosus_. _Type_:
+      Museum d'Histoire Naturelle, Paris, no. A. 7787 (Thomas, 1921:141),
+      "very imperfect."
+
+      _Diagnosis._--Aristiforms wide; P4 and M1 with two counterfolds;
+      p4 with two counterfolds, one anterior to main fold.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 18 to 20 mm;
+      maximum width, 0.8 mm. _Aristiforms on outer thighs_: Color much
+      faded; total length, 15 to 17 mm; maximum width, 0.3 mm.
+      _Setiforms on middorsal region_: Color faded; total length, 16 to
+      18 mm; maximum width, 0.04 mm. _Setiforms on outer thighs_: Color
+      faded; total length, 10 to 13 mm; maximum width, 0.03 mm.
+
+[Illustration: FIGS. 129-132. _Proechimys setosus elegans_, sex ?, UZM
+no. L 104, Lagoa Santa. × 1.]
+
+      _Skull._--Short; rostrum short and stout; length of nasals
+      approximately 15 mm (broken); bullae roundish, smooth and
+      well-inflated; jugals dorso-ventrally narrow (3.1 mm) with strong
+      transverse ridge; postorbital process of zygoma spiniform, slender
+      and involving mostly jugal; incisive foramen narrow (3.8 x 1.7 mm)
+      and narrowest in posterior part; vomerine sheath complete;
+      posterior palatine foramina obsolete; mesopterygoid fossa extending
+      forward as far as middle of second molars.
+
+      _Teeth._--Incisors orthodont. P4 with two counterfolds; M1 with
+      two counterfolds but anterior one notably small; M2 and M3 with
+      only one counterfold each. In lower jaw: p4 with two counterfolds,
+      one anterior to main fold; molars with only one counterfold.
+
+      _Comparisons._--From _P. s. elegans_, _setosus_ differs in: M1 with
+      two counterfolds as opposed to only one; M3 with one counterfold
+      instead of sometimes with two counterfolds; p4 with one counterfold
+      anterior to main fold and another posterior, instead of both
+      counterfolds posterior.
+
+_Remarks._--The measurements above were taken from the Maximilian
+specimen mentioned above. Measurements of the type were given by
+Desmarest as: head and body, 5-1/2 inches, tail about 6-1/2 inches. Is.
+Geoffroy Saint-Hilaire (1838:886) corrects these measurements to: head
+and body 195 mm; tail (part missing), 170 mm.
+
+
+=Proechimys setosus elegans= (Lund)
+
+      _E[chimys]. elegans_ Lund, 1841, Kong. Danske Videnskab. Selsk.
+      natur-vidensk. math. Afhandl., Kjöbenhavn, 8:99 (orig. descr.).
+
+      _Loncheres elegans_ Lund, 1841, Kong. Danske Videnskab. Selsk,
+      natur-vidensk. math. Afhandl., Kjöbenhavn, 8:245, 266, 294;
+      Wagner, 1843, Wiegman's Archiv f. Naturg., Berlin, 2 (Jahrg.
+      9):47.
+
+      _Echimys cayennensis_ Waterhouse, 1848, Nat. Hist., Mammalia,
+      2:337.
+
+      _Echinomys cajennensis_ Winge, 1888, Jordfundne og nulevende
+      Gnavere (Rodentia), E Museo Lundii, Kjöbenhavn, 1(3):71,
+      pl. 6, figs. 5-6, pl. 7, fig. 1.
+
+      _Proechimys setosus_ Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser.
+      9):141.
+
+      _Proechimys elegans_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _Type locality._--Lagoa Santa, _Nova Lima_, Minas Gerais, Brazil.
+      _Type_: Syntypes in Universitets Zoologiske Museum, Kjöbenhavn;
+      collected by P. W. Lund.
+
+      _Range._--Known only from the type locality.
+
+      _Diagnosis._--Aristiforms wide; P4 usually with two counterfolds;
+      M3 sometimes with two counterfolds; p4 with two counterfolds
+      anterior to main fold.
+
+      _Pelage._--_Aristiforms on middorsal region_: Gray basally,
+      gradually blackening toward tip; total length, 18 to 20 mm;
+      maximum width, 0.7 mm. _Aristiforms on outer thighs_: Gray
+      basally, gradually blackening toward tip which is Cinnamon; total
+      length, 15 to 17 mm; maximum width, 0.3 mm. _Setiforms on
+      middorsal region_: Whitish basally, gradually blackening toward
+      tip, but interrupted by Cinnamon, subapical zone; total length, 17
+      to 19 mm; maximum width, 0.04 mm. _Setiforms on outer thighs_:
+      Whitish basally, gradually blackening toward tip but interrupted
+      by near (15''_a_) Cinnamon, subapical zone; total length, 10 to 12
+      mm; maximum width, 0.03 mm.
+
+      _Skull._--Short; rostrum short but not stout; length of nasals 17
+      mm; bullae large, smooth, and well-inflated; jugals with
+      conspicuous, transverse ridge; postorbital process of zygoma long,
+      spiniform and constructed entirely of jugal; incisive foramen
+      narrow (4 × 1.7 mm); vomerine sheath complete and slender;
+      posterior palatine foramina obsolete; mesopterygoid fossa
+      extending anteriorly as far as middle parts of second molars.
+
+      _Teeth._--Incisors orthodont. P4 usually with two counterfolds,
+      rarely with three; upper molars with only one counterfold, but M3
+      sometimes with two, posterior one being vestigial. Lower
+      molariform teeth: p4 with two counterfolds, both being anterior to
+      main fold; molars with only one counterfold.
+
+      _Comparisons._--Differences from _P. s. setosus_ are given in the
+      account of that subspecies.
+
+_Remarks._--According to Lund, these animals are found in the vicinity
+of small pools, swim well in spite of not having webbed toes, at night
+go after food and climb the corn stalks, and have their nests in the
+grass at the margins of the pools.
+
+      _Specimens examined._--Total number, 2 (UZM), from Brazil, Minas
+      Gerais, _Nova Lima_, Lagoa Santa.
+
+
+=Proechimys albispinus= (Is. Geoffroy)
+
+      _General characters._--Size small; tail of same length as head and
+      body or slightly less; feet small; ears of medium size; color of
+      upper parts Ochraceous-Tawny gradually changing to Ochraceous-Buff
+      on sides; differentiated, light-colored aristiforms on back, sides,
+      rump and at base of tail; clavate aristiforms on back with
+      Ochraceous-Tawny or Ochraceous-Buff, subapical zone; underparts of
+      body and inner sides of legs white; tail blackish above, white
+      below, with no white tip; hands and feet white on dorsal parts and
+      some specimens darker on outer margins of feet; skull short and
+      smooth, somewhat flattened in frontal region; jugal dorso-ventrally
+      wide and with moderately conspicuous transverse ridge; postorbital
+      process of zygoma well developed and involving both jugal and
+      squamosal; bullae large and smooth; incisive foramen short and
+      narrow; vomerine sheath incomplete or complete; molariform teeth
+      with only one counterfold; incisors orthodont or proodont.
+
+_Remarks._--A good series from Macaco Seco, Andaraí, Bahia, agrees
+closely with the form first described (_albispinus_) from the Island
+Madre de Deus, in Todos os Santos Bay, Bahia. Compared with topotypes of
+_P. albispinus sertonius_, the animal from Macaco Seco in general color
+is more Ochraceous-Tawny and has a narrower skull with orthodont
+incisors. Specimens from Bonfim, northeastern Bahia, on the other hand,
+agree with Thomas' _albispinus sertonius_, from Lamarão, being browner
+and having broader skulls than _P. a. albispinus_ and having proodont,
+instead of orthodont, incisors. The range of each of the two subspecies
+is, therefore, fairly extensive. The insular form extends to the less
+rainy, continental area and the form from Lamarão ranges northward (NNW)
+in the same type of highly deciduous forest, the "caatinga."
+
+The species _albispinus_ is certainly the most specialized form of the
+entire genus for drier habitats. In addition to the general adaptations
+described above, it is noteworthy for having both lanceolate and clavate
+aristiforms. The latter type has a wide basal part and an abruptly
+narrowed, distal part. The same development is seen in the genus
+_Echimys_, where highly spinous forms, like _Echimys paleacea_
+(Lichtenstein), show the same two types of aristiforms.
+
+[Illustration: FIGS. 133, 135. _Proechimys albispinus albispinus_, male,
+CNHM no. 20409, Macaco Seco. × 1.]
+
+[Illustration: FIGS. 134, 136. _Proechimys albispinus sertonius_, male,
+MN no. 6454, Bonfim. × 1.]
+
+[Illustration: FIGS. 137, 138. _Proechimys albispinus albispinus_, male,
+CNHM no. 20409, Macaco Seco. × 1.]
+
+[Illustration: FIGS. 139, 140. _Proechimys albispinus sertonius_, male,
+MN no. 6454, Bonfim. × 1.]
+
+
+=Proechimys albispinus albispinus= (Is. Geoffroy)
+
+      _Echimys albispinus_ Is. Geoffroy Saint-Hilaire, 25 June 1838,
+      Comptes Rendus Acad. Sci., Paris, 6(26):886; Is. Geoffroy, August,
+      1838, Ann. Sci. Nat., Paris, 10 (ser. 2):125; Is. Geoffroy,
+      1840, Mag. Zool., Paris (ser. 2, année 2, livr. 13):33, 53, pl. 26,
+      pl. 29 (figs. 1, 2, 3); Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):261.
+
+      _Echinomys fuliginosus_ Wagner, 1843, Schreber's Säugethiere,
+      suppl., 3:343.
+
+      _Echimys albispinosus_ Waterhouse, Nat. Hist., Mammalia, 2:341.
+
+      _Proechimys albispinus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):264; Thomas, 1911, Ann. Mag. Nat. Hist., 8 (ser. 8):252.
+
+      _Proechimys albispinus albispinus_ Thomas, 1921, Ann. Mag. Nat.
+      Hist., 8 (ser. 9):141; Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):401; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:122.
+
+      _Type locality._--Ilha Madre de Deus, _Itaparica_ (near Salvador),
+      Bahia, Brazil. _Type_: Museum d'Histoire Naturelle, Paris, no. A
+      7669, "skull ... practically perfect" (Thomas, 1921:142).
+
+      _Range._--Island Madre de Deus, Macaco Seco, Andaraí and probably
+      islands of the bay of Todos os Santos and valley of the Paraguassú
+      River.
+
+      _Diagnosis._--Aristiforms wide; color on setiforms
+      Ochraceous-Tawny on upper parts and sides; incisors orthodont;
+      molariform teeth with one counterfold, p4 rarely with two.
+
+      _Pelage._--_Aristiforms on middorsal region_: Lanceolate
+      aristiforms, with basal part whitish, gradually blackening toward
+      tip; total length, 25 to 28 mm; maximum width, 1.2 mm; clavate
+      aristiforms with base whitish, gradually blackening toward tip but
+      interrupted by Ochraceous-Tawny, subapical zone. _Aristiforms on
+      outer thighs_: Whitish on basal half, gradually blackening toward
+      tip; total length, 24 to 26 mm; maximum width, 0.9 mm. Some are
+      whitish basally, gradually blackening toward distal part but
+      distal fourth or fifth near (15'_j_) Ochraceous-Tawny. _Setiforms
+      on middorsal region_: Whitish basally, gradually blackening toward
+      tip but interrupted by Ochraceous-Tawny, subapical zone; total
+      length, 20 to 23 mm; maximum width, 0.1 mm. Some setiforms almost
+      completely whitish. _Setiforms on outer thighs_: Whitish basally,
+      gradually blackening toward tip but interrupted by near (15'_j_)
+      Ochraceous-Tawny, subapical zone; total length, 18 to 20 mm;
+      maximum width, 0.06 mm.
+
+      _Skull._--Narrow; bullae small and smooth; jugals dorso-ventrally
+      wide with conspicuous transverse ridge; postorbital process of
+      zygoma well-developed and formed by jugal and squamosal; posterior
+      palatine foramina obsolete; incisive foramen narrow and short;
+      vomerine sheath complete or incomplete but premaxillary part at a
+      level lower than that of maxillary part (when skull is viewed from
+      ventral face); mesopterygoid fossa extending forward as far as
+      anterior borders of second molars.
+
+      _Teeth._--Incisors orthodont; molariform teeth with only one
+      counterfold, except that p4 rarely has two counterfolds.
+
+      _Comparisons._--From _P. a. sertonius_, _albispinus_ differs in:
+      sides of body darker; incisors orthodont as opposed to proodont;
+      p4 rarely with two counterfolds instead of always with one
+      counterfold.
+
+_Remarks._--The localities where _P. a. albispinus_ has been collected
+have a forest climax with a moderate percentage of deciduous trees.
+
+      _Specimens examined._--Total number, 19 (18 CNHM, 1 MCZ), from
+      Brazil, Bahia, _Andaraí_, Macaco Seco.
+
+
+=Proechimys albispinus sertonius= Thomas
+
+      _Proechimys albispinus sertonius_ Thomas, July, 1921, Ann. Mag.
+      Nat. Hist., 8 (ser. 9):142 (orig. descr.); Tate, 1935, Bull. Amer.
+      Mus. Nat. Hist., 68(5):401; Ellerman, 1940, The families and genera
+      of living rodents, Brit. Mus. (Nat. Hist.), 1:122.
+
+      _Type locality._--Lamarão ("about 70 miles north of Bahia City"),
+      _Ituiutaba_, Bahia, Brazil; altitude 300 meters. _Type_: British
+      Museum (Nat. Hist.), no. 3.9.5.86, adult male; collected on 16
+      June, 1903, by Alphonse Robert; original number, 1508.
+
+      _Range._--Known from the type locality and Bonfim; probably
+      occupies valleys of Jacuipe and the Itapicurú rivers and littoral
+      between them.
+
+      _Diagnosis._--Aristiforms wide; color of setiforms
+      Ochraceous-Tawny on back, grading to Ochraceous-Buff on sides;
+      incisors proodont; no molariform tooth with more than one
+      counterfold.
+
+      _Pelage._--_Aristiforms on middorsal region_: Lanceolate
+      aristiforms whitish basally, gradually blackening toward tip;
+      total length, 23 to 27 mm; maximum width, 1.3 mm. Clavate
+      aristiforms, and some lanceolate ones, whitish basally, gradually
+      blackening toward tip but interrupted by Ochraceous-Tawny,
+      subapical zone. Some clavate aristiforms without subapical zone
+      but blackened in distal part; total length, 23 to 24 mm; maximum
+      width, 0.7 mm. _Aristiforms on outer thighs_: Whitish basally,
+      gradually blackening toward tip but interrupted by Light
+      Ochraceous-Buff, subapical zone; tip slightly darker; some whitish
+      basally, grayish in middle and light yellowish toward tip; total
+      length, 20 to 22 mm; maximum width, 0.9 mm.
+      _Setiforms on middorsal region_: Whitish basal part succeeded by
+      grayish, then by long, light, yellowish band, which becomes Light
+      Ochraceous-Buff, and blackish tip; total length, 26 to 29 mm;
+      maximum width, 0.15 mm. _Setiforms on outer thighs_: Whitish basal
+      part succeeded by grayish, then Light Ochraceous-Buff, subapical
+      zone and blackish tip; total length, 18 to 20 mm; maximum width,
+      0.13 mm.
+
+      _Skull._--Broad; bullae small and smooth; jugals dorso-ventrally
+      "wide," with conspicuous transverse ridge; postorbital process of
+      zygoma well-developed and formed by both jugal and squamosal;
+      incisive foramen narrow and short; vomerine sheath incomplete or
+      complete but premaxillary part on a lower level than maxillary
+      part (when skull is viewed from ventral face); mesopterygoid fossa
+      extending forward as far as anterior faces of second molars.
+
+      _Teeth._--Incisors proodont; molariform teeth with only one
+      counterfold.
+
+      _Comparisons._--Differences from _P. a. albispinus_ are given in
+      the account of that subspecies.
+
+_Remarks._--Localities where samples were collected are typical
+"caatinga" forest, a climax of mainly deciduous trees; cacti are also
+common in the region.
+
+      _Specimens examined._--Total number, 10, from Brazil, Bahia, as
+      follows: _Ituiutaba_, Lamarão, 4 (1 DZ, 1 CNHM, 1 MCZ, 1 USNM);
+      _Bonfim_, Bonfim, 6 (5 DZ, 1 MN).
+
+
+
+
+INCERTA SEDIS
+
+
+=Proechimys myosuros= (Lichtenstein)
+
+      _Loncheres myosuros_ Lichtenstein, 1818, Das zoologische Museum der
+      Universität zu Berlin, (2):18 (_nomen nudum_); Lichtenstein, 1820,
+      Abhandl. K. Akad. Wissensch., Berlin (1818-1819):192, pl. 1, fig. 2
+      (orig. descr.); Wied, 1826, Beiträge zur Naturgeschichte von
+      Brasilien, 2:445.
+
+      _Mus leptosoma_ Brants, 1827, Het geslacht der Muizen door
+      Linnaeus opgesteld ..., Berlyn, p. 150; Lichtenstein, 1830,
+      Darstellung neuer oder wenig bekannter Säugethiere, Berlin, Heft
+      7, pl. 36, fig. and text pages.
+
+      _Mus cinnamoneus_ Lichtenstein, 1830, Darstellung neuer oder wenig
+      bekannter Säugethiere, Berlin, Heft 7, pl. 36.
+
+      _Echimys myosuros_ Is. Geoffroy Saint-Hilaire, 1838, Comptes
+      Rendus Acad. Sci., 6(26):886, and 1840, Mag. Zool., Paris (ser. 2,
+      année 2):15, 33, 53; Allen, 1899, Bull. Amer. Mus. Nat. Hist.,
+      12(20):261.
+
+      _Echinomys leptosoma_ Wagner, 1843, Schreber's Säugethiere,
+      suppl., 3:341.
+
+      _Echinomys myosuros_ Burmeister, 1854, Syst. ubersicht Thiere
+      Brasiliens, p. 199.
+
+      _Proechimys setosus_ Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser.
+      9):141.
+
+      _Proechimys myosuros_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5):400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _Proechimys leptosoma_ Tate, 1935, Bull. Amer. Mus. Nat. Hist.,
+      68(5): 400; Ellerman, 1940, The families and genera of living
+      rodents, Brit. Mus. (Nat. Hist.), 1:119.
+
+      _General characters._--Aristiforms wide (1''') and numerous
+      on dorsal parts of body; tail longer (9'') than head and body
+      (8''); hind feet short (1''6''').
+
+      _Color_ (According to Lichtenstein and Brants'
+      descriptions).--Black between ears; dark brown on middorsal line
+      with reddish tinge on front and upper side of neck; posteriorly
+      from shoulders there is a greasy shine added to color; this dark,
+      dorsal band widens posteriorly, there encroaching on sides of
+      body; sides lighter brown, sparsely marked with dark brown lines,
+      from sides of head caudad to, and including, outer surfaces of
+      hind legs; outer sides of forelegs colored like outer sides of
+      hind legs; ankles ringed with brown. Tail blackish above, whitish
+      below. Upper surfaces of hands and feet white.
+
+      _Skull._--No description of skull or teeth found.
+
+_Remarks._--Thomas (1921:140-143) summarized the available information
+on the forms from southeastern Brazil and synonymised _myosuros_ with
+_setosus_. The description of _leptosoma_ by Brants applies to this same
+species except in a few features. However, neither Brants nor
+Lichtenstein described the tail of _myosuros_ as having a white tip or
+even as having a heavily pencilled tip, although Wagner (1843:342) in
+redescribing Lichtenstein's species indicated that the tail had a white
+pencil. He gave also measurements of the head and body, and tail, which
+do not agree with the original measurements given by either Lichtenstein
+or Brants. Lichtenstein, in the original description, gave the type
+locality of _myosuros_ as Bahia, and stated that it was collected by
+Freireiss. Brants also gave Bahia as the type locality for _leptosoma_.
+The names _leptosoma_ Brants and _cinnamoneus_ Lichtenstein are
+evidently no more than duplicate names for _myosuros_, as pointed out by
+Thomas (1921:141) and subsequent writers. Specimens referred to any of
+these forms, therefore, could take the earlier name _myosuros_ until
+identified otherwise. Lichtenstein later (1830, text for plate 36, fig.
+2) added São Paulo State to the known range of the species, mentioning
+specimens collected there by Sello. Probably, therefore, Wagner
+redescribed _leptosoma_ using a composite sample; the white tip on the
+tail could occur in any race of _P. iheringi_ from São Paulo.
+
+Considering the short hind feet and the wide aristiforms, _Proechimys
+myosuros_ probably will eventually prove to be related to _albispinus_;
+perhaps it will prove to be a synonym of _albispinus_.
+
+
+
+
+CONCLUSIONS
+
+
+      1. The genus _Proechimys_ is divisible into two subgenera. In all
+      Brazil there are four full species of each subgenus, or 8 species
+      in all. All but one of these are divisible into subspecies of which
+      there are 29, making a total of 30 kinds in Brazil; 14 of these are
+      here newly named.
+
+      2. It is new information, I think, that: (1) One main fold
+      extending entirely across the worn crown of the molariform tooth
+      is peculiar to _Trinomys_; in the subgenus _Proechimys_, apparent
+      complete division of the crown surface is accomplished by a short
+      main fold meeting a counterfold originating on the opposite side
+      of the tooth; (2) progressive decrease in size of molariform teeth
+      from P4 to M3 is peculiar to the subgenus _Trinomys_; in the
+      subgenus _Proechimys_, M2 is largest and the teeth are
+      progressively smaller anteriorly.
+
+      3. In the one species, _Proechimys albispinus_, which has the
+      widest distribution of aristiforms on the body of any species in
+      the genus, some of the aristiforms are clavate. Clavate
+      aristiforms occur in the most spiny species of the related genus
+      _Echimys_.
+
+      4. In subspecies of any one full species the incisive foramen is
+      larger in animals which inhabit arid areas than in those which
+      inhabit humid areas. Possibly increased area of moist mucosa
+      associated with Jacobson's organ is required in arid areas for
+      maintenance of the necessary keenness of smell.
+
+      5. The number of counterfolds in the molariform teeth vary in
+      clinal fashion. Their variation is in response to humidity.
+      Increasing humidity is correlated with increasing number of folds,
+      and decreasing humidity is correlated with decreasing number of
+      folds.
+
+      6. Clinal variation correlated with increasing humidity is to be
+      seen also in longer tail and darker color of pelage.
+
+      7. The primitive _Proechimys_ probably was large, with a short
+      tail, narrow aristiforms, strongly built skull, and five
+      counterfolds in each molariform tooth.
+
+      8. Geographic isolation appears to have been a factor in the
+      establishment of the two subgenera; the arid belt along the São
+      Francisco River and northward to Ceará appears to be uninhabited
+      by _Proechimys_ and constitutes a barrier separating the two
+      subgenera, _Proechimys_ and _Trinomys_.
+
+      9. This arid belt probably developed relatively early, since in
+      deposits of late Pleistocene age, remains of the subgenus
+      _Trinomys_ have been found in the area where the subgenus still
+      occurs.
+
+      10. The most primitive types occur at the periphery of the range
+      of the genus.
+
+      11. Populations from small islands tend to be more primitive than
+      populations on the mainland. Insular populations develop a
+      homozygous condition with resultant disappearance of secondary
+      biotypes.
+
+      12. Insular animals ordinarily are larger than their mainland
+      counterpart.
+
+
+
+
+TABLE OF MEASUREMENTS
+
+TABLE 1.--Measurements (in millimeters) of adults of _Proechimys_
+
+  Key:
+
+  A Length of head and body
+  B Length of tail
+  C Length of hind-foot
+  D Length of ear from notch
+  E Greatest length of skull
+  F Condylo-incisive length
+  G Zygomatic breadth
+  H Length of nasals
+  I Interorbital constriction
+  J Palatilar length
+  K Crown length of cheekteeth
+
+  ======================================================================================
+                         A     B     C     D     E     F     G     H     I     J      K
+  --------------------------------------------------------------------------------------
+  _P. g. steerei_, [M] [M] Hyutanaham
+  USNM 105535           218   123    48    17   53.5  44.0  25.2  19.3  11.7  18.2   8.2
+  USNM 105536           217   135    50         55.2  45.3  25.7  20.7  11.4  19.2   8.0
+         ?
+  USNM 105537                                   56.3  44.9  24.0  20.4  11.4  19.3   8.7
+  --------------------------------------------------------------------------------------
+  _P. g. goeldii_, [M] Fazenda Paraiso
+  AMNH 37489            218          52    20   55.1  44.9  27.0  22.1  12.0  18.6   9.4
+         [F]
+  AMNH 37488            228   157    49    22   57.3  47.6  27.9  22.1  12.4  20.3   9.6
+  ======================================================================================
+  _P. s. liminalis_, [M] [M] Rio Quichito
+  Mean                  229   145    43    21   58.4  47.6  27.3  21.8  12.9  20.1   8.3
+  Maximum               250          45    24   61.7  50.0  28.9  23.0  13.8  21.2   8.8
+  Minimum               210          40    18   53.3  44.3  25.5  19.4  12.0  18.5   7.9
+  No. of specimens        5     1     5     5    5     5     5     5     5     5     5
+         [F] [F]
+  MN 6253               215   150    43    20   57.5  46.5  28.3  21.5  12.0  19.4   8.7
+  MN 6250               213          42    20   60.8  49.7        22.0  13.7  21.0   9.1
+  --------------------------------------------------------------------------------------
+  _P. s. amphichoricus_, [M] [M] Esmeralda
+
+  AMNH 77000            252   163    53         60.8  50.3  27.5  24.4  13.7  20.7   9.4
+  AMNH 76994            260   160    54                     25.5  22.8  12.6         9.5
+  AMNH 77020            250   181    57         62.0  52.0  27.3  25.9  13.8  21.5   9.6
+         [F]
+  AMNH 76999            235   149    50                           24.0        19.0   9.3
+  --------------------------------------------------------------------------------------
+  _P. s. kermiti_, [F] Lower Solimões
+  AMNH 37124            210          55         65.2  53.7  29.2  27.6  13.5  21.4   9.0
+  --------------------------------------------------------------------------------------
+  _P. l. brevicauda_, [M] João Pessoa
+  DZ 900                245   147    48         58.3  46.6  26.5  22.5  11.6  18.2   8.2
+  --------------------------------------------------------------------------------------
+  _P. l. boimensis_, [M] Boim
+  MCZ 30881             220   160    50         54.6  44.2  24.8  21.0  11.7  17.3   7.5
+         [F]
+  MN 1976               182   140    45         52.6  42.2  24.3  20.8  11.4  16.8   7.6
+         [F] Cametá
+  MCZ 30878             240          48         55.1  45.0  25.2  22.4  11.5  18.4   7.6
+  --------------------------------------------------------------------------------------
+  _P. l. longicaudatus_, [M] Urucum
+  CNHM 26732            229   121    48                           21.5  11.5  18.5   8.3
+         [F] [F]
+  AMNH 37085            210   150    44         51.4  42.5  24.3  19.5  10.8  17.1   8.9
+  AMNH 37086            210          50         48.5  40.9  23.7  17.1  10.2  17.1   8.3
+  --------------------------------------------------------------------------------------
+  _P. l. leucomystax_, [M] Tapirapoã
+  AMNH 37509            230   150    43         50.7  42.2  24.5  18.4  10.3  17.5   8.1
+         [F]
+  AMNH 37510            210          42         48.1  41.3  23.0  16.9   9.9  17.2   8.1
+         [F] Utiarití
+  MN 2212                                       48.0  39.9        18.3  11.2  15.9   8.0
+         [F] Salto Sepotuba
+  MN 1936               202   147    44         52.6  43.0  23.6  19.2  10.7  17.8   7.8
+  --------------------------------------------------------------------------------------
+  _P. l. roberti_, [M] [M] Anapolis
+  Mean                  208   159    45    21   52.7  43.5  24.9  20.7  13.1  17.2   7.9
+  Maximum               235   190    55    25   56.1  47.8  27.1  23.7  12.0  19.1   8.2
+  Minimum               170   135    36    18   48.1  40.0  22.8  18.2  10.6  15.6   7.6
+  No. of specimens       16    14    16    16   11    11    11    11    11    11    11
+         [F] [F]
+  Mean                  219   149    44    20   51.1  42.3  24.1  20.0  10.7  17.2   8.0
+  Maximum               290   155    48    24   55.5  45.4  25.8  21.5  11.1  17.7   8.7
+  Minimum               195   125    40    18   48.9  40.3  23.1  19.1  10.5  16.6   7.7
+  No. of specimens       10     8    10    10    7     7     7     7     7     7     7
+  ======================================================================================
+  _P. g. villicauda_, [M] [M] Tapirapoã
+  MN 1932               225   145    47         55.6  45.5  26.8  24.0  12.0  18.1   8.9
+  MN 1934               215   162    50         56.2  46.0  26.1  21.3  12.0  18.6   8.4
+         [M] Utiarití
+  AMNH 57544            250   200    55                        .  24.3  13.1  19.9   9.1
+  --------------------------------------------------------------------------------------
+  _P. g. ribeiroi_, [M] Rio 12 de Outubro
+  MN 1935               190   134    47         50.1  41.0  24.3  20.0  11.5  15.9   8.1
+  --------------------------------------------------------------------------------------
+  _P. g. hyleae_, [M] [M] Tauarí
+  Mean                  248   146    52         58.1  47.6  27.1  22.9  12.1  19.4   8.5
+  Maximum               260   174    53         59.0  47.8     .  23.4  13.2  20.0   8.8
+  Minimum               217   143    51         57.2  46.5     .  22.4  11.1  18.8   8.3
+  No. of specimens        4     3     4          2     2     1     2     2     2     2
+         [F] [F]
+  Mean                  229   149    50         54.3  44.9  25.8  21.0  11.8  18.1   8.5
+  Maximum               270   168    54         56.1  46.3  27.4  23.0  13.4  19.3   9.0
+  Minimum               190   132    49         51.5  42.9  24.5  19.1  11.1  17.1   7.9
+  No. of specimens       10     9    10          9    11    11    10    10    10    10
+  --------------------------------------------------------------------------------------
+  _P. g. nesiotes_, [M] Ilha de Manapirí
+  CNHM 19496            201   133    47    20   52.7  42.7  25.1  19.5  11.1  17.8   8.0
+         [F]
+  MN 1975               200   152    47    21   52.1  42.6  25.8  19.5  12.3  18.3   8.0
+  --------------------------------------------------------------------------------------
+  _P. g. leioprimna_, [F] [F] Cametá
+  AMNH 37484            192   151    41    22   54.8  44.9  25.4  19.2  12.6  18.4   8.4
+  CNHM 19503            189   164    47    22   54.4  43.7  26.2  20.5  12.6  18.2   8.2
+  CNHM 19536            189          43    22
+  --------------------------------------------------------------------------------------
+  _P. g. oris_, [M] Providencia
+  CNHM 19495            230   170    45    24   56.1  47.1  25.8  22.0  11.4  17.4   8.3
+         [M] Tanaquará
+  MN 1974               230   175    49    23   53.2  43.0  23.8  20.1  10.5  17.9   7.7
+         [M] Rio Guamá
+  AMNH 37487            205   142    42    21
+  --------------------------------------------------------------------------------------
+  _P. g. arescens_, [M] [M] Fazenda Inhuma
+  CNHM 26440            206   149    51    24   54.7  44.1  26.3  21.4  12.1  18.7   8.3
+  CNHM 26441            191   164    51         55.6  45.0  25.7  22.4  11.7  18.7   8.7
+  --------------------------------------------------------------------------------------
+  _P. g. riparum_, [F] Manaus
+  AMNH 143018           225          44    20   52.6  43.2  24.0  20.5  11.0  17.2   6.7
+  --------------------------------------------------------------------------------------
+  _P. g. arabupu_, [M] [M] Arabupu
+  AMNH 75816            243   220    56         59.2  48.7  27.0  23.8  12.9  17.8   8.7
+  AMNH 75819            230   181    52         55.0  46.0  26.0  22.5  12.3  16.9   8.3
+  AMNH 75815            228   198    52
+         [F] [F]
+  AMNH 75810            226   170    48         53.9  45.6  25.6  21.0  12.0  16.1   8.3
+  AMNH 75823            209   188    48         53.4  43.9  24.5  21.5  11.7  16.4   8.3
+  AMNH 75817            204   167    47         51.1  43.1     .  21.6  11.3  16.6   8.2
+  --------------------------------------------------------------------------------------
+  _P. dimidiatus_, [M] [M] Pedra Branca
+  Mean                  199   170    46         52.4  43.5  26.2  19.5  12.1  16.4   8.3
+  Maximum               220   195    50         56.4  47.1  27.5  21.5  13.6  18.0   8.7
+  Minimum               180   150    44         48.1  40.4  24.6  17.5  11.0  14.4   7.4
+  No. of specimens       19    18    19         45    46    45    45    46    46    46
+         [F] [F]
+  Mean                  197   162    44         51.8  42.9  25.8  19.4  11.8  16.3   8.3
+  Maximum               230   180    46         55.1  45.9  27.4  22.0  13.0  18.4   8.9
+  Minimum               165   145    42         48.6  39.5  23.8  17.6  10.7  14.8   7.7
+  No. of specimens       14    12    14         42    44    44    42    44    44    44
+  --------------------------------------------------------------------------------------
+  _P. i. iheringi_, [M] [M] Ilha de São Sebastião
+  Mean                  207   197    48         54.5  44.6  26.2  19.9  12.0  18.3   8.3
+  Maximum               220   205    50         55.0  45.2  27.1  20.4  12.8  18.7   8.5
+  Minimum               196   190    46         53.5  43.7  25.9  19.3  10.9  17.5   8.0
+  No. of specimens        5     2     5          5     5     4     4     5     5     5
+         [F] [F]
+  MN 6453               228   185    46         54.3  44.5  25.9  20.5  11.0  18.9   8.2
+  DZ 2095               205   180    46         53.2  42.9  26.4  18.9  11.1  17.0   8.2
+  DZ 2525               205          46         56.9  45.8  27.8  20.9  12.5  18.9   8.2
+  --------------------------------------------------------------------------------------
+  _P. i. bonafidei_, [M] [M] Fazenda Bõa Fé
+  Mean                  211   186    50    25   53.3  43.4  25.6  20.2  12.1  16.3   8.5
+  Maximum               220   194    54    26   55.8  45.2  26.3  21.7  13.2  17.4   9.1
+  Minimum               200   176    47    24   50.7  41.0  24.2  19.1  11.0  14.8   8.1
+  No. of specimens        7     5     8     8    4     5     5     7     7     7     7
+         [F] [F]
+  Mean                  209   185    52    25   52.6  44.4  26.6  20.0  12.4  16.4   8.6
+  Maximum               226   203    55    27   56.9  46.4  28.6  21.4  13.2  17.0   9.2
+  Minimum               185   153    50    22   44.4  42.3  24.9  18.0  11.4  15.5   8.2
+  No. of specimens        7     7     7     7    6     6     7     7     7     7     7
+  --------------------------------------------------------------------------------------
+  _P. i. gratiosus_, [M] [M] Floresta da Caixa Dagua
+  Mean                  193   191    48         51.2  41.4  25.5  18.5  11.7  16.3   8.0
+  Maximum               200   200    49         51.7  42.2  27.0  18.9  12.0  16.7   8.2
+  Minimum               185   175    47         50.5  40.4  24.6  18.0  11.1  15.6   7.9
+  No. of specimens        5     5     5          5     5     5     5     5     5     5
+         [F] [F]
+  Mean                  204   175    49    24   50.5  42.1  26.0  18.4  11.4  16.3   7.9
+  Maximum               220   190    50    26   52.6  43.1  26.6  19.5  12.1  17.5   8.2
+  Minimum               195   160    47    22   48.4  41.0  25.3  17.5  10.7  15.3   7.6
+  No. of specimens        5     2     5     4    4     4     4     4     4     4     4
+  --------------------------------------------------------------------------------------
+  _P. i. paratus_, [M] [M] Floresta da Capela de São Braz
+  MN 4023               203   195    54    28   51.2  41.7  25.4  18.3  10.4  16.2   8.4
+  MN 5458               190   170    51    27
+         [F]
+  MN 4012               220   210    54    29   52.2  42.3  25.4  19.1  12.3  17.5   8.7
+  --------------------------------------------------------------------------------------
+  _P. i. panema_, [M] [M] Campinho
+  MN 8286               215          45    23   54.0  45.1  27.7  19.5  13.4  16.4   8.1
+  MN 8284               195   180    43    23   51.5  41.8  24.5  18.1  11.4  16.0   7.6
+         [F] [F]
+  MN 8288               190   190    46    21   51.6  42.8  25.3  18.1  11.7  15.7   7.9
+  MN 8287               200   190    46    23   52.6  43.6  27.2  18.4  12.5  16.7   8.3
+  MN 8285               190          45    24   50.0  41.1  26.6  19.4  12.3  16.1   8.1
+  --------------------------------------------------------------------------------------
+  _P. i. denigratus_, [M] [M] Mata do Ribeirão da Fortuna
+  Mean                  197   218    52    24   51.5  42.2  25.7  18.3  11.3  16.0   8.2
+  Maximum               217   242    54    28   55.4  45.3  27.0  20.3  12.4  17.6   8.5
+  Minimum               190   204    50    21   48.7  39.5  23.7  16.8  10.4  15.0   8.0
+  No. of specimens       10     9     9    10    8     8     8     8     8     8     8
+         [F] [F]
+  Mean                  201   207    52    24   49.1  41.2  25.0  18.3  11.2  16.0   7.8
+  Maximum               225   225    54    28   54.1  44.6  25.7  21.5  11.8  17.1   8.3
+  Minimum               180   175    49    20   48.2  39.5  23.5  17.4  10.5  15.5   7.5
+  No. of specimens       12    12    12    12    8     8     8     8     8     8     7
+  --------------------------------------------------------------------------------------
+  _P. s. setosus_, ? No locality
+  AMNH 16140                                          39.8  25.2        11.0  15.9   7.6
+  --------------------------------------------------------------------------------------
+  _P. s. elegans_, [M] Lagoa Santa
+  UZM H82               190   190    47    25               24.3  17.5  11.2  16.6   7.7
+         ?
+  UZM L104                                      48.6  40.8  24.8  16.6  10.3  15.9   7.7
+  ======================================================================================
+  _P. a. albispinus_, [M] [M] Macaco Seco
+  Mean                  175   162    40         45.9  39.7  23.6  15.6  10.6  15.7   7.6
+  Maximum               193   173    47         48.2  42.0  24.9  17.1  11.6  17.5   8.2
+  Minimum               165   147    38         44.2  38.1  22.7  14.8   9.7  14.3   7.2
+  No. of specimens        9     8     9         11    12    12    14    13    14    13
+         [F] [F]
+  CNHM 20402            187   171    40         46.0  40.8  23.8  14.9  11.3  16.0   7.4
+  CNHM 20408                                    47.6  40.7  24.6  17.1  11.2  15.9   8.2
+  --------------------------------------------------------------------------------------
+  _P. a. sertonius_, [M] Lamarão
+  CNHM 18196            190   160    36    25                           11.7
+         [M] Bonfim
+  MN 6454               185   175    37         45.7  39.8  24.2  15.5  10.7  16.1   7.5
+         [F] [F]
+  DZ 2636               190   150    35         43.8  37.6  22.8  14.7   9.6  14.5
+  DZ 2635               175   155    38         46.7  40.6  23.3  16.9  10.2  15.1   7.4
+  --------------------------------------------------------------------------------------
+
+
+
+
+LITERATURE CITED
+
+
+  ALLEN, J. A.
+      1904. Mammals from the District of Santa Marta, Colombia, collected
+      by Mr. Herbert H. Smith, with field notes by Mr. Smith. Bull. Amer.
+      Mus. Nat. Hist., 20:407-468, November 28, 1904.
+
+      1916. Mammals collected on the Roosevelt Brazilian Expedition,
+      with field notes by Leo E. Miller. Bull. Amer. Mus. Nat. Hist.,
+      35:559-610, August 9, 1916.
+
+  AMEGHINO, F.
+      1934. Notas sobre una pequéna coleccion de huesos de mamiferos,
+      procedentes de las grutas calcáreas de Iporanga en el Estado São
+      Paulo (Brasil), Obras completas y Correspondencia Cientifica de
+      Florentino Ameghino, La Plata, 17:103-153.
+
+  BERRY, E. W.
+      1942. Mesozoic and Cenozoic plants of South America, Central
+      America and the Antilles. Proc. Eighth Amer. Sci. Congress,
+      4:365-373.
+
+  DESMAREST, A. G.
+      1817. Nouveau Dictionaire d'Histoire Naturelle, ed. 2, 10:59.
+
+  ELLERMAN, J. R.
+      1940. The families and genera of living Rodents. Vol. 1, Rodents
+      other than Muridae, pp. xxvi + 689, 189 text figs. British Museum
+      (Natural History). June 8, 1940.
+
+  GEOFFROY SAINT-HILAIRE, ISIDORE
+      1840. Notice sur les rongeurs épineux, désignés par lés auteurs
+      sous les noms d'_Echimys_, _Loncheres Heteromys_ et _Nelomys_. Mag.
+      Zool. (Guerin-Meneville), s. 2, Ann. 2, pp. 1-57, pls. 20-29.
+
+  LICHTENSTEIN, M. H. C.
+
+      1830 (1827-34). Darstellung neuer oder wenig bekannter Säugethiere,
+      65 Arten, etc., pp. 118, 50 pls. colored.
+
+  LUND, P. W.
+      1841. Blik paa Brasiliens Dyreverden för sidste Jordomvaeltning, af
+      Dr. Lund. Kongelige Danske Videnskabernes Selskabs
+      naturvidenska-belige og mathematiske. Fortsaettelse af
+      Pattedyrene. Kjöbenhavn, 2:217-272, pls. 14-24.
+
+  OLIVEIRA, A. I., and LEONARDOS, O. H.
+
+      1943. Geologia do Brasil. Min. da Agricultura. Rio de Janeiro, 26 +
+      813, 202 figs., photographs, 1 map.
+
+  OSGOOD, WILFRED H.
+      1944. Nine new South American rodents. Zool. Ser. Field Mus. Nat.
+      Hist., 29:191-204, July 12, 1944.
+
+  RIBEIRO, ALIPIO DE MIRANDA
+      1914. Historia Natural. Zoologia. Mammiferos. Commissão de Linhas
+      Telegraficas, Estrategicas de Matto Grosso ao Amazonas. Annexo no.
+      5, Rio de Janeiro, pp. 1-49 + 1-3, pls. 25, May, 1914.
+
+  RIDGWAY, ROBERT
+      1912. Color standards and color nomenclature, iv + 44 pp., 53 pls.
+      Published by the author, Washington, D. C.
+
+  TATE, G. H. H.
+      1935. The taxonomy of the genera of Neotropical hystricoid rodents.
+      Bull. Amer. Mus. Nat. Hist., 68:295-447, June 12, 1935.
+
+      1939. The mammals of the Guiana Region. Bull. Amer. Mus. Nat.
+      Hist., 76:151-229, October 20, 1939.
+
+  THOMAS, OLDFIELD
+      1900. Descriptions of new rodents from western South America. Ann.
+      and Mag. Nat. Hist., 6(ser. 7):294-302, September, 1900.
+
+      1905. New Neotropical _Molossus_, _Conepatus_, _Nectomys_,
+      _Proechimys_, and _Agouti_, with a note on the genus _Mesomys_.
+      Ann. and Mag. Nat. Hist., 15(ser. 7):584-591, June, 1905.
+
+      1912. On small mammals from the Lower Amazon. Ann. and Mag. Nat.
+      Hist., 9(ser. 8):84-90, January, 1912.
+
+      1920. On mammals from the Lower Amazons in the Goeldi Museum,
+      Pará. Ann. and Mag. Nat. Hist., 6(ser. 9):266-283, September,
+      1920.
+
+      1921. On the spiny rats of the _Proechimys_ group from
+      Southeastern Brazil. Ann. and Mag. Nat. Hist., 8(ser. 9):140-143,
+      July, 1921.
+
+  WAGNER, ANDREAS
+      1843. Beschreibung einiger neuer Nager, welche auf der Reise des
+      Herrn Hofrats v. Schubert gesammelt wurden, mit Bezugnahme auf
+      einige andere verwandte Formen. Abhandl. Akad. Wiss. math.-phys.
+      Cl., 3(4):173-216, pl. 2.
+
+  WAGNER, J. A.
+      1844 (1774-1846). In Schreber's Die Säugethiere ..., 7 pts.
+      including text and pls., colored (347).
+
+  WIED, MAXIMILIAN ZU
+      1826. Beiträge zur Naturgeschichte von Brazilien, vol. 2, Mammalia,
+      600 pp., 6 pls., Weimar.
+
+  WINGE, HERLUF
+      1888. Jordfundne og nulevende Gnavere (Rodentia) fra Lagoa Santa,
+      Minas Gerais, Brasilien. E Museo Lundii Afhandlinger, 1(3):1-178,
+      pls. 1-8.
+
+      1941. The interrelationships of the mammalian genera. Translated
+      from Danish by E. Deichmarm and G. M. Allen. København, 3 vols.
+      (vol. 1, xii + 418), 3 pls., 1941; vol. 2, 376 pp., 1941; vol. 3,
+      308 pp., 1942.
+
+
+  _Transmitted, December 1, 1947._
+
+
+                                   22-3343
+
+
+
+
+Transcriber's notes:
+
+- inconsistent use of m (for meter/s) throughout the whole book.
+  e.g.: 100 m or 120 m, etc.
+- 'TABLE 1.--Measurements (in millimeters) of adults of _Proechimys_'
+  left in its (remaining) width ( >  col. 75) for best possible overview.
+
+
+
+
+
+End of the Project Gutenberg EBook of Speciation in the Brazilian Spiny Rats, by 
+João Moojen
+
+*** END OF THE PROJECT GUTENBERG EBOOK 42720 ***