diff options
| -rw-r--r-- | .gitattributes | 3 | ||||
| -rw-r--r-- | 38021-8.txt | 2698 | ||||
| -rw-r--r-- | 38021-8.zip | bin | 0 -> 41795 bytes | |||
| -rw-r--r-- | 38021-h.zip | bin | 0 -> 301417 bytes | |||
| -rw-r--r-- | 38021-h/38021-h.htm | 3279 | ||||
| -rw-r--r-- | 38021-h/images/001.jpg | bin | 0 -> 2461 bytes | |||
| -rw-r--r-- | 38021-h/images/184a.jpg | bin | 0 -> 20062 bytes | |||
| -rw-r--r-- | 38021-h/images/184b.jpg | bin | 0 -> 22562 bytes | |||
| -rw-r--r-- | 38021-h/images/188.jpg | bin | 0 -> 54022 bytes | |||
| -rw-r--r-- | 38021-h/images/189.jpg | bin | 0 -> 55374 bytes | |||
| -rw-r--r-- | 38021-h/images/190.jpg | bin | 0 -> 56896 bytes | |||
| -rw-r--r-- | 38021-h/images/191.jpg | bin | 0 -> 49897 bytes | |||
| -rw-r--r-- | 38021.txt | 2698 | ||||
| -rw-r--r-- | 38021.zip | bin | 0 -> 41730 bytes | |||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 |
16 files changed, 8691 insertions, 0 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/38021-8.txt b/38021-8.txt new file mode 100644 index 0000000..67929e6 --- /dev/null +++ b/38021-8.txt @@ -0,0 +1,2698 @@ +Project Gutenberg's The Baculum in Microtine Rodents, by Sydney Anderson + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Baculum in Microtine Rodents + +Author: Sydney Anderson + +Release Date: November 15, 2011 [EBook #38021] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + + + + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + UNIVERSITY OF KANSAS PUBLICATIONS + MUSEUM OF NATURAL HISTORY + + Volume 12, No. 3, pp. 181-216, 49 figs. + + February 19, 1960 + + The Baculum in Microtine Rodents + + BY + SYDNEY ANDERSON + + UNIVERSITY OF KANSAS + LAWRENCE + 1960 + + UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY + + Editors: E. Raymond Hall, Chairman, Henry S. Fitch, + Robert W. Wilson + + Volume 12, No. 3, pp. 181-216, 49 figs. + Published February 19, 1960 + + UNIVERSITY OF KANSAS + Lawrence, Kansas + + PRINTED IN + THE STATE PRINTING PLANT + TOPEKA, KANSAS + 1960 + +[Illustration] + + 28-774 + + + + +The Baculum in Microtine Rodents + +BY + +SYDNEY ANDERSON + +INTRODUCTION + + +Didier (1943, 1954) has described the bacula of several Old World +microtines, and other rodents. Argyropulo studied (1933a, 1933b) five +species of Cricetinae and _Microtus socialis_. Ognev (1950) illustrated +numerous species of Eurasian microtines. Hamilton (1946) figured and +described the baculum of 11 species of North American microtines. Hibbard +and Rinker (1942, 1943) figured the baculum of _Synaptomys cooperi +paludis_ and of _Microtus ochrogaster taylori_. Dearden (1958) studied +the baculum in two Asiatic species of _Lagurus_, in six subspecies of +_Lagurus curtatus_ of North America, and in six other species of +microtines of other genera. + +The baculum can be preserved easily with standard study skins, and is +potentially useful in interpreting relationships on any taxonomic level, +and especially in determining the relationships of species within a +genus, if used together with other structures. + +The anatomical orientation of the baculum needs comment because some +confusion exists in the literature, especially concerning the use of the +terms ventral and dorsal. The urethra lies on the anatomically ventral +side of the penis, and of the baculum. In the center of the penis lies a +single corpus cavernosum penis, shown in cross section proximal to the +baculum in Figure 1c. Dorsally an artery, thinner walled than the ventral +urethra, ends in a somewhat reticulate sinus surrounding primarily the +middle part of the baculum within the bulbous glans penis. The corpus +cavernosum penis (the structure has no median septum, at least distally) +terminates with the baculum and is closely knit to it. The site of this +bond is evident in the tuberosities and sculpturing of the base of the +baculum. + +The part of the penis enclosing the baculum, when not erect, is folded +back as shown in Figures 1a and 1b. As a result the anatomically ventral +surface faces upwards, or at least posterodorsally. The use of the term +ventral in this account refers to the anatomically ventral side, that is +to say to the side of the baculum facing the urethra. + +The baculum in microtines consists of an elongate stalk, having a +laterally, and to a lesser extent dorsoventrally, expanded base and an +attenuate distal shaft. Usually, three digitate processes of +cartilaginous material in which additional ossifications may occur arise +from the terminus of the shaft. The proportions and curvature of the +stalk vary as do the proportions of the terminal ossifications to each +other and to the stalk. In some species one or more of the digital +processes are frequently completely unossified. + +[Illustration: FIGURE 1. The baculum in _Microtus +ochrogaster_--orientation and variation with age. _a._ Diagram of a +sagittal section of the posterior half of a vole, natural size. The +penis, containing the baculum (in black), extends ventrally from a point +posterior to the pubic symphysis (stippled), along the body wall, and +bends posteriorly at the distal end. _b._ Distal end of penis (× 2) +showing baculum (in black), the urethra (solid lines) adjacent to the +baculum, and the corpus cavernosum (broken lines) proximal to the +baculum. _c._ Oblique view of the cross section of penis (× 4) shown in +Figure 1 _b_. The thick-walled urethra lies ventral to the curved corpus +cavernosum. A thinner-walled blood-vessel lies dorsal to the corpus +cavernosum. The anatomically ventral side of the baculum, in the normal +non-erect penis shown, is seen to face dorsally. _d._ Graph showing the +relationship between size of baculum, size of animal, and development of +digital ossifications. Circles show presence of ossification in stalk +only; circles enclosing dots indicate presence of secondary ossification +in median process also; large dots indicate the addition of tertiary +ossification in one or both of the lateral digitate processes.] + +Preserved specimens of _Microtus arvalis_, _Microtus agrestis_, _Microtus +orcadensis_, _Microtus nivalis_, _Microtus guentheri_, _Microtus +subterraneus_, _Clethrionomys glareolus_, and _Ellobius lutescens_ were +provided by Prof. Robert Matthey of Lausanne, Switzerland. J. Knox Jones, +Jr. carefully saved the bacula with specimens of _Microtus fortis_ and +_Clethrionomys rufocanus_ from Korea. Dr. W. B. Quay, Department of +Zoology, University of California, supplied specimens of _Synaptomys +cooperi_, _Phenacomys intermedius_, and _Microtus oregoni_. Dr. Franklin +Sturges and Mr. John W. Goertz, Museum of Natural History, Oregon State +College, Corvallis, have provided specimens including bacula of +_Clethrionomys occidentalis_, _Microtus oregoni_, and _Microtus +townsendii_. Dr. Randolph L. Peterson and Mr. Bristol Foster, Royal +Ontario Museum of Zoology, Toronto, Canada, provided specimens of +_Phenacomys intermedius_. Dr. J. N. Layne, University of Florida, +Gainsville, Florida, presented me with a baculum of _Microtus parvulus_. + +I am indebted to all of these persons for their aid, and to various +collectors for the Museum of Natural History, who preserved bacula with +specimens. Many of these specimens were obtained through the assistance +of the University of Kansas Endowment Association and the National +Science Foundation. + + + + +METHODS + + +Bacula were obtained from fresh specimens, specimens preserved in alcohol +or formalin, and dried study skins. The processing of bacula has been +discussed by Hamilton (1946), Friley (1947), White (1951), and Dearden +(1958). The methods used to preserve bacula for my study differed some +from any of those reported. The terminal part of each penis including the +baculum imbedded in the glans penis was removed in its entirety and +placed in a vial. The catalogue number was kept with each specimen at all +times. A two per cent solution of potassium hydroxide was added. All +specimens were examined at least once a day. If tissues other than the +glans penis were present they were removed with forceps when softened +usually at the end of one day. Several drops of Alizarin red-S stain in a +saturated alcoholic solution were added to the 3 to 5 ccs. of KOH +solution in each vial. Solutions were replaced if they became turbid +enough to obstruct observation of the clearing penis. After one day the +solution containing stain was removed and replaced with two per cent KOH +solution without stain. When the glans became sufficiently cleared that +the stained baculum could be seen easily, the solution was replaced by +glycerin in which clearing was completed. The time required for the +entire process varied from one day to more than two weeks depending on +the size of the specimen and on its condition. Fresh specimens clear more +rapidly than dried specimens, and those that are dried more rapidly than +those that are preserved. A three or four per cent solution of hydroxide +will hasten the process, but more frequent observation is required to +prevent excessive maceration. + +Specimens were then examined in a shallow dish containing glycerin under +a binocular microscope. The baculum can be viewed from any desired +direction. The method described above leaves the baculum intact within +the glans penis; therefore its orientation can be determined relative to +the thick walled urethra and the thin walled dorsal artery that extends +onto the dorsal side of the baculum. The ventral curvature of the penis +proximal to the baculum, and the distal extension, characteristic of most +species, of the dorsal border of the glans (both shown in Figure 1) are +other features aiding in correctly orienting cleared specimens. The +digitate processes are not so often injured, lost, or displaced when the +method described above is used as they are when the penis is dissected. +Specimens were stored in glycerin in glass shell vials having +polyethylene stoppers. A small card bearing the name, number, locality, +and other data was placed in each vial. A specimen thus enclosed can be +kept indefinitely, or removed and mounted in balsam as described by White +(1951:631) or in plastic as described by Dearden (1958:541) and thus +stored in the vial containing the skull of the specimen. + +Drawings were made on millimeter ruled paper while the baculum was viewed +under a binocular microscope with a square ruled eyepiece. + +Unless otherwise noted all specimens listed are in the University of +Kansas Museum of Natural History. Catalogue numbers are cited. +Measurements are accurate to within less than one-tenth of a millimeter. +Proportions as stated in the text are approximations, accurate to within +one-twelfth (8.33 per cent). The range of variation is unknown for some +species. Mention is made if maturity is known or suspected to differ in +specimens being compared. + +The development of the baculum has been studied by Callery (1951) in +_Mesocricetus auratus_ and by Ruth (1934) in the laboratory rat. In the +rat (_Rattus norvegicus_) the bone is of endoblastemal origin being laid +down by a condensation of undifferentiated mesenchymal cells. At the +distal end of the bone dense fibrous tissue is then differentiated and at +the proximal end hyaline cartilage. Growth is by substitution at the +proximal end and by subperiosteal lamellation circumferentially. A marrow +cavity is formed by resorption. In the baculum of the hamster the primary +center of ossification is in the stalk, and is present at the age of +three days; the secondary centers are in lateral processes and are +present at 80 days and enlarge subsequently. A tertiary center, in each +median process, may or may not develop later. Maximum development of the +baculum is reached late in the reproductive life of the hamster. + +The early ossification of the baculum noted in the rat and the hamster +occurs in _Microtus_ also. A specimen of _Microtus montanus fusus_ +(76831, from 5 mi. N, 26 mi. W Saguache, 9600 ft., Saguache County, +Colorado) only 74 mm. in total length and weighing only 6.6 grams, had a +slender ossified baculum having enlarged ends. This vole was one-half of +the average length and less than one-fifth of the average weight of an +adult, and of approximately the size at which weaning takes place. + +The development of the baculum in _Microtus ochrogaster_ was studied in +32 specimens of various ages. The specimens (between Nos. 74994 and +75074) were collected between August 15 and September 4, 1957, at +localities on the Great Plains. These specimens were from breeding +populations, as evidenced by pregnancy of females and by large size of +testes of males. The length and width of the stalk of the baculum, the +presence of digital ossifications, the total length of the animal, and +the size of the testes were noted. Variability in length of testes is +greatest when voles are from 140 to 150 mm. in total length. Sexual +maturity is reached rather abruptly when the total length of most +individuals is 140 to 150 millimeters. If the baculum likewise underwent +more rapid growth at the onset of sexual maturity, greater variability +should be evident in the length of the baculum of voles 140 to 150 mm. in +total length than in bacula of voles of other sizes. This was the case +(see Figure 1d). The baculum does not, however, suddenly reach its +maximum maturity. + +The primary ossification is in the stalk. The secondary ossification is +in the median process except in _Lagurus_ (Dearden, 1958:551) and some +individuals of _Neofiber_ (see account on page 258). Tertiary centers of +ossification are in the lateral processes. The primary ossification is +present at an early age and subsequently increases in size and solidity. +The secondary and tertiary ossifications are progressively more common in +older voles. The increase in degree of ossification of all parts +continues after sexual maturity is reached. Individual variation and +variation with age in the baculum of _Microtus pennsylvanicus_ have been +illustrated by Hamilton (1946:380). Figures 14, 15, and 17 illustrate +variation with size, which is correlated with age, and also illustrate +individual variation. The three bacula are from adult voles having testes +that measured 15, 16 and 16 mm. in length, respectively. Each vole was +trapped in late June. The total lengths in millimeters of the three voles +are 172, 167, and 181; weights are 55, 52.4, and 65.5 grams. I judge that +the greater size of the stalk and the better developed base shown in +Figure 17 than in Figure 15 are illustrative of age variation; the +difference in the size of the lateral digitate processes is, in this +case, attributable to individual variation. Differences in the distal end +of the baculum in Figures 42 and 43, show individual variation also. +Figures 35 and 36 represent two different subspecies; different +individuals of _M. mexicanus mogollonensis_, however, exhibit individual +variation of the same degree. + +Hall and Cockrum (1953) list 44 species of microtines in North America. +At least twelve of these are insular or local forms perhaps derived from +some other species; for example _Microtus coronarius_, an insular form +derived from _Microtus longicaudus_; _Microtus provectus_, considered by +Chamberlain (1954:587) and by Wheeler (1956:176) as a subspecies of +_Microtus pennsylvanicus_; and _Microtus ludovicianus_, a close relative +of _Microtus ochrogaster_. + +All North American genera have been studied. Of the genus _Microtus_ in +North America, all subgenera but _Orthriomys_ and all species but the +following nine, have been studied: _M. (Orthriomys) umbrosus_, the +insular _M. (Stenocranius) abbreviatus_, _M. (Microtus) breweri_, _M. +(Microtus) nesophilus_, _M._ + +[Illustration: FIGURES 2-13. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. Exact localities are +given in accounts of species concerned. + +2. _Lemmus trimucronatus_, 50678, Point Barrow, Alaska. + +3. _Dicrostonyx groenlandicus_, 50539, Porcupine Lake, Brooks Range, +Alaska. + +4. _Dicrostonyx groenlandicus_, 52524, Point Barrow, Alaska. + +5. _Synaptomys cooperi saturatus_, WBQ 3-C-454, 3 mi. S Demotte, Indiana. + +6. _Synaptomys cooperi paludis_, 13716, Meade County State Park, Kansas. + +7. _Phenacomys intermedius celatus_, SA 2044, Quebec. + +8. _Phenacomys intermedius intermedius_, WBQ 3-C-309, 5.4 mi. S Moran, +Teton Co., Wyoming. + +9. _Clethrionomys rufocanus_, 60438, 1 mi. NW Oho-ri, Korea, (_d_) +ventral view. + +10. _Clethrionomys gapperi_, 42108, 31 mi. N Pinedale, Wyoming. + +11. _Clethrionomys rutilus_, 42865, 5 mi. NNE Gulkana, Alaska. + +12. _Clethrionomys occidentalis_, FWS 30, Mary's Peak, Benton Co., +Oregon. + +13. _Clethrionomys glareolus_, 67100, Zermatt, Valais, Switzerland.] + +[Illustration: FIGURES 14-25. Bacula of _Microtus_. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with dorsal surface upward. + +14. _M. pennsylvanicus_, 42439, 1 mi. S, 2 mi. E Eagle Nest, Colfax Co., +New Mexico; abnormality perhaps owing to injury; dorsal view. + +15. _M. pennsylvanicus_, 42306, 5 mi. N, 26 mi. W Saguache, Colorado; +dorsal view. + +16. _M. pennsylvanicus_, 43043, 20 mi. NE Anchorage, Alaska, ventral +view. + +17. _M. pennsylvanicus_, 42430, 1 mi. S, 2 mi. E Eagle Nest, New Mexico. + +18. _M. agrestis_, 67102, Gryon, Switzerland. + +19. _M. montanus amosus_, 62241, 1/2 mi. E Soldier Summit, Wasatch Co., +Utah. + +20. _M. montanus nanus_, 57470, 2 mi. N, 2 mi. W Pocatello, Idaho. + +21. _M. montanus fusus_, 42307, 5 mi. N, 26 mi. W Saguache, Colorado. + +22. _M. arvalis_, 67101, Vidy, Switzerland, possibly not mature. + +23. _M. guentheri_, 67104, Palestine. + +24. _M. orcadensis_, 67106, Orkney Islands, orientation uncertain. + +25. _M. fortis_, 63841, Chipo-ri, Korea, (_d_) ventral view.] + +[Illustration: FIGURES 26-39. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. + +26. _M. (Pitymys) fatioi_, 67103, Zermatt, Switzerland, immature. + +27. _M. (Pitymys) pinetorum_, 76834, 2 mi. N Baldwin, Douglas Co., +Kansas. + +28. _M. (Pitymys) pinetorum_, 68545, 1 mi. NE Pleasant Grove, Kansas. + +29. _M. (Pitymys) quasiator_, 30709, Teocelo, Veracruz, (_d_) ventral +view. + +30. _M. (Pitymys) quasiator_, 19878, 5 km. N Jalapa, Veracruz. + +31. _M. (Pedomys) ochrogaster_, 75036, 1 mi. N, 2 mi. E Oberlin, Kansas. + +32. _M. (Stenocranius) miurus_, 51152, Lake Schrader, Brooks Range, +Alaska. + +33. _M. (Stenocranius) miurus_, 51169, Lake Schrader, Brooks Range, +Alaska. + +34. _M. (Stenocranius) gregalis_, 8059, "Eastern Europe." + +35. _M. mexicanus mexicanus_, 63094, Valle de Bravo, Estado de México, +México. + +36. _M. mexicanus mogollonensis_, 63298, Mt. Taylor, Valencia Co., New +Mexico. + +37. _M. californicus_, 76828, 1 mi. NE Berkeley, California; (_d_) +ventral view. + +38. _M. (Arvicola) richardsoni_, 42454, 31 mi. N Pinedale, Sublette Co., +Wyoming. + +39. _M. richardsoni_, 37903, 23-1/2 mi. S, 5 mi. W Lander, Wyoming; +distal end.] + +[Illustration: FIGURES 40-49. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. + +40. _Microtus (Pitymys) parvulus_, UF 1508, 1 mi. W Micanopy, Florida. + +41. _Microtus townsendii_, 79186, Sec. 33, T. 11S, R. 5W, Benton Co., +Oregon. + +42. _Microtus (Herpetomys) guatemalensis_, 65895, 2 mi. S San Juan Ixcoy, +Guatemala. + +43. _M. guatemalensis_, 65921, 10 mi. E, 4 mi. S Totonicapan, Guatemala, +dorsal view of tip. + +44. _Microtus oeconomus_, 43048, Kelsall Lake, British Columbia. + +45. _Microtus (Chilotus) oregoni_, WBQ 3-C-248, 5 mi. N Orick, +California. + +46. _Lagurus (Lemmiscus) curtatus_, 26053, 9 mi. S Robertson, Uinta Co., +Wyoming. + +47. _Microtus (Chionomys) nivalis_, 65127, Wetterstein, Germany, +orientation uncertain. + +48. _Microtus (Chionomys) longicaudus_, 50253, Crane Flat, Mariposa Co., +California. + +49. _Neofiber alleni_, 27268, 2 mi. S Gainesville, Florida, orientation +uncertain.] + +(_Microtus_) _provectus_ (the last three are probably insular derivatives +of _M. pennsylvanicus_), _M._ (_Microtus_) _fulviventer_ (perhaps derived +from the same stock as _Microtus mexicanus_), _M._ (_Microtus_) +_xanthognathus_ (perhaps related to _Microtus chrotorrhinus_), _M._ +(_Microtus_) _coronarius_, and _M._ (_Pedomys_) _ludovicianus_. + + +SPECIES OF WHICH BACULA WERE EXAMINED + + Subfamily: Microtinae Number of Specimens + Tribe: Lemmi + _Dicrostonyx groenlandicus_ (Traill) 4 + _Lemmus trimucronatus_ (Richardson) 6 + _Synaptomys cooperi_ Baird 5 + Tribe: Microti + Genus: _Clethrionomys_ Tilesius, 1850 + _Clethrionomys rutilus_ Pallas 4 + _Clethrionomys gapperi_ (Vigors) 9 + _Clethrionomys occidentalis_ (Merriam) 1 + _Clethrionomys glareolus_ Schreber 1 + _Clethrionomys rufocanus_ Sundevall 1 + Genus: _Phenacomys_ Merriam, 1897 + _Phenacomys intermedius_ Merriam 5 + Genus: _Ondatra_ Link, 1795 + _Ondatra zibethicus_ (Linnaeus) 1 + Genus: _Microtus_ Schrank, 1798 + (_Herpetomys_) _guatemalensis_ Merriam 3 + (_Arvicola_) _richardsoni_ (DeKay) 2 + (_Chilotus_) _oregoni_ (Bachman) 3 + (_Stenocranius_) _gregalis_ (Pallas) 1 + (_Stenocranius_) _miurus_ Osgood 9 + (_Chionomys_) _longicaudus_ (Merriam) 6 + (_Chionomys_) _nivalis_ Martins 2 + (_Microtus_) _arvalis_ (Pallas) 1 + (_Microtus_) _orcadensis_ Millais 1 + (_Microtus_) _guentheri_ Danford and Alston 1 + (_Microtus_) _fortis_ Büchner 2 + (_Microtus_) _montanus_ (Peale) 15 + (_Microtus_) _townsendii_ (Bachman) 3 + (_Microtus_) _oeconomus_ (Pallas) 10 + (_Microtus_) _mexicanus_ (Saussure) 13 + (_Microtus_) _californicus_ (Peale) 2 + (_Microtus_) _pennsylvanicus_ (Ord) 13 + (_Microtus_) _agrestis_ (Linnaeus) 1 + (_Pedomys_) _ochrogaster_ (Wagner) 41 + (_Pitymys_) _pinetorum_ (LeConte) 2 + (_Pitymys_) _parvulus_ (Howell) 1 + (_Pitymys_) _quasiater_ (Coues) 5 + (_Pitymys_) _fatioi_ Mottaz 1 + Genus: _Neofiber_ True, 1884 + _Neofiber alleni_ True 2 + Genus: _Lagurus_ Gloger, 1841 + _Lagurus curtatus_ (Cope) 7 + + Total number examined 184 + + + + +ACCOUNTS OF SPECIES + + +Dicrostonyx groenlandicus (Traill) + +Figs. 3 and 4 + +Baculum: stalk elongate, greatest length (3.1 mm.) 2-1/5 to 2-1/2 times +greatest breadth, and 4-1/2 times greatest depth; digitate processes +usually cartilaginous, occasionally lateral processes partly ossified; +basal tuberosities weakly to moderately developed, medially confluent; +posterior profile in dorsal view rounded with rounded posterior apex or +shallow notch; dorsal concavity in end-view shallower and not so wide as +ventral concavity; median constriction approximately 2/3 greatest depth; +ventral part of base in end-view wider than dorsal part; shaft straight +or slightly curved; base of stalk placed dorsally relative to axis of +shaft; stalk spatulate, sometimes with distal enlargement; at mid-point +stalk wider than high; lateral profile in dorsal view sloping gradually +without abrupt curvature anterior to point of greatest width. + +The baculum of _Dicrostonyx torquatus_ figured by Ognev (1948:476) agrees +with that of _D. groenlandicus_ in shape of stalk, and in lateral +digitate processes that are small relative to size of median process; but +differs in more elongate, terminally enlarged, bulbar shape of median +process. None of my specimens showed ossification in the lateral +processes, observed by Hamilton (1946:381) in _Dicrostonyx rubricatus +richardsoni_ [ = _D. groenlandicus richardsoni_]. In all of my specimens +the cartilaginous median process was larger than that figured by +Hamilton, or by Dearden (1958:542). + +_Specimens examined_: Four from; Point Barrow, Alaska, 52524 (Barrow +Village), 67264 (died in captivity); Brooks Range, Alaska, 50536 (Wahoo +Lake, 69°08', 146°58'), 50539 (Porcupine Lake, 68°51'57", 146°29'50", +3140 ft.). + + +Lemmus trimucronatus (Richardson) + +Fig. 2 + +Baculum: Stalk heavy, broad, greatest length (2.8 mm.) in mature +individuals (Fig. 2) as little as 1-1/3 times greatest breadth, greatest +length no less than 2-2/3 times greatest depth of base; three ossified +processes, median one from as long as to 1/2 longer than the lateral +processes, and approximately 2/3 wider and twice as deep as lateral +processes; length of median process almost 3-1/2 times its breadth, +approximately 1/2 length of stalk; basal fossae broadly confluent; +posterior profile in dorsal view evenly rounded; in end-view ventral +concavity deeper than dorsal concavity, constriction as little as 1/2 +greatest depth in mature specimens; shaft straight, bluntly rounded, or +slightly decurved and laterally inflated terminally; lateral profile in +dorsal view a gradual slope from widest point of stalk anteriorly onto +shaft; in younger individuals stalk slenderer, otherwise as described +above. + +Five specimens examined by me differ from one figured and described by +Hamilton (1946:379) in that stalk is better developed, larger relative to +size of processes, length of stalk in my specimen (Fig. 2) 2.8 as opposed +to 2.1 mm. in Hamilton's specimen; median process shorter, 1.5 as opposed +to 1.8 mm., proximal end rounded rather than concave, not partially +enclosing tip of shaft; proportion of and relative sizes of median and +lateral processes approximately same as in Hamilton's _Lemmus helvolus_ +[ = _Lemmus trimucronatus helvolus_]. A specimen figured by Dearden +(1958:542) has a basally trilobed median process. + +The baculum of the Asiatic _Lemmus lemmus_ figured by Ognev (1948:413) +agrees with my specimens in the ossification of three processes, the +relative sizes of these processes to each other and to the stalk, the +well-developed base of the stalk and heavy bluntly rounded shaft; the +baculum of _Lemmus lemmus_ differs in greater anterolateral extent of +basal tuberosities, in proximal notch seemingly separating these +tuberosities, and in median process being slenderer. + +_Specimens examined_: Five, of two subspecies; _Lemmus trimucronatus +alascensis_, Point Barrow, Alaska, numbers 50591, 50678, 50731, 50758; +_Lemmus trimucronatus subarcticus_, Wahoo Lake, 69°08', 146°58', 2350 +ft., Brooks Range, Alaska, 50948. + + +Synaptomys cooperi Baird + +Figs. 5 and 6 + +Baculum: Stalk elongate, greatest length (2.7 to 2.8 mm.) 2-1/3 to 2-1/2 +times greatest breadth, 4 to 5 times greatest depth; three processes +ossified or lateral processes unossified, ossifications relatively small +(in 78380, median ossification less than 1/4 as large as lateral +ossifications although median cartilaginous process is larger), length of +median process 1/5 to 1/6 of length of stalk, cartilaginous part of +median process larger; posterior profile in dorsal view convex throughout +or bilobate; tuberosities moderately developed, deflected dorsal to axis +of shaft; in end-view medial construction 3/5 greatest depth of +tuberosities; shaft tapered from point of greatest width, slightly +inflated terminally. + +The specimen (KU 13716) figured by Hibbard and Rinker (1942:29) has been +restudied. It was first cleared and stained to soften the dry cartilage +binding the digital processes together and to differentiate bone and +cartilage. The lateral processes are small and cartilaginous (Fig. 6) and +seem intact. The differences between this specimen and others examined by +Hamilton (1946:381), Dearden (1958:542), and myself, namely the +relatively larger median ossification, the absence of ossification in +lateral processes, and the distinctly bilobate base and larger size, may +represent geographic differences, or individual variation. The +proportions of length, width, and depth of the stalk, and the appearance +in lateral view do not differ greatly from others examined by Hamilton, +by Dearden (1958:546), and by me. + +_Specimens examined_: Five, representing four subspecies; _S. cooperi +gossii_, 6 mi. N Midway, Holt Co., Nebraska 78379, 78380; _S. cooperi +relictus_, 5 mi. N, 2 mi. W Parks, Dundy Co., Nebraska, 72601 (immature); +_S. cooperi saturatus_, 3 mi. S Demotte, Jasper Co., Indiana, 3-C-454, +collection of W. B. Quay; _S. cooperi paludis_, Meade County State Park, +Kansas, 13716. + + +Clethrionomys rutilus Pallas + +Fig. 11 + +Baculum: Stalk elongate, and proximally enlarged, greatest length (2.7 +mm.) 2 times greatest breadth; less than 4 times greatest depth; three +well-developed ossified processes; length of stalk 2-1/3 times length of +median process; median process with basal (and ventral) protuberence and +lateral lobes, arched in dorsoventral plane; lateral processes as large +as median process, flattened distally, having ventromedial vane on distal +half; basal tuberosities of stalk well developed, medially confluent; +posterior profile in dorsal view trilobate or convex throughout with +rounded posterior apex; dorsal concavity well developed, ventral surface +but slightly concave, medial constriction of base as little as 1/2 +greatest depth; shaft straight, slender, at mid-point of stalk but +slightly wider than high; basal tuberosities largely dorsal to axis of +shaft in lateral view; lateral profile in dorsal view with an abrupt +curvature separating the gently sloping sides of the shaft from the basal +part at its greatest breadth. + +The specimen of _Clethrionomys rutilus_ figured by Ognev (1950:120) is +essentially like the North American specimens examined by me in the +relative sizes of the ossifications and the general shape of the stalk. + +_Specimens examined_: Four, of one subspecies; _C. r. dawsoni_, west bank +Gakona River, 1700 ft., 5 mi. NNE Gulkana, Alaska, 42865, 42866; SW end +Dezadeash Lake, 2400 ft., Yukon Territory, 42910, 42921. + + +Clethrionomys gapperi (Vigors) + +Fig. 10 + +Baculum: Stalk elongate, greatest length (2.8 mm.) 1-3/4 times greatest +breadth, and 3-3/4 times greatest depth; proximally enlarged, greatest +depth 1/2 greatest breadth; three well-developed ossified processes; +length of stalk 2-1/3 times length of median process; median process +arched in dorsoventral plane, with basiventral protuberence or spine and +lateral lobes; lateral processes as large as median process, flattened +distally, arched; basal tuberosities of stalk well developed, medially +confluent; posterior profile in dorsal view trilobate or convex +throughout with a rounded posterior apex; dorsal concavity well +developed, ventral surface but slightly concave, or in some cases +slightly convex; medial constriction of base 3/5 greatest depth; shaft +straight, slender, at mid-point of stalk twice as wide as high; basal +tuberosities dorsally placed relative to axis of shaft; lateral profile +in dorsal view abruptly curved anterior to point of greatest width; +slender stalk distinct from angular enlarged base. + +The most noticeable difference between the baculum of _C. rutilus_ and +_C. gapperi_ is size. The proportions of the four ossifications are +approximately the same. Ventral vanes on the lateral processes are not +developed in _C. gapperi_. _C. gapperi_ and _C. rutilus_ are more nearly +alike in their bacula than any other two species of _Clethrionomys_ +examined. _Clethrionomys occidentalis_, the other New World species, is +also much like _C. gapperi_ and _C. rutilus_. The differences are of a +magnitude comparable to those between the bacula in subspecies of +_Microtus montanus_ (Figs. 19-21) for example, or in subspecies of +_Lagurus curtatus_ (Dearden, 1958:542). + +_Specimens examined_: Nine, of two subspecies; _Clethrionomys gapperi +athabascae_, British Columbia, 42922 (Indian Creek, Mile Post 234 of +Alaskan Highway), 64281 (West bank Racing River, 89 mi. W Muskwa), 64287 +(North bank Tetsa River, 56 mi. W, 11 mi. S Muskwa), 64290 (44 mi. W, 9 +mi. S Muskwa), 64310 (32 mi. W, 2 mi. S Muskwa); _Clethrionomys gapperi +galei_, 31 mi. N Pinedale, Sublette Co., Wyoming, 42108; Grand Mesa, +Delta Co., Colorado, 60014 and 60015 (5-1/2 mi. E, 12 mi. S Collbran), +60022 (8 mi. E, 1/2 mi. S Skyway). + + +Clethrionomys occidentalis (Merriam) + +Fig. 12 + +Baculum: Stalk elongate, greatest length (2.8 mm.) 2-1/2 times greatest +breadth, 6 times greatest depth; three well-developed ossified processes; +median process larger than lateral processes, 1/2 the length of stalk, +curved, basally broad, ventrally keeled, trilobate posteriorly; lateral +ossifications large, flattened distally, curved; posterior profile of +stalk posteriorly slightly emarginate, thus bilobate in outline; in +end-view dorsal concavity deeper than ventral, constriction less than 1/2 +greatest depth, tuberosities confluent, visible in dorsal view at each +side; shaft slender, especially in depth, straight; at mid-point of stalk +almost twice as wide as deep, slight terminal inflation. + +The general proportions of the stalk and the relatively large, uniquely +shaped processes, are characteristic of most specimens of the genus +_Clethrionomys_ examined. + +_Specimen examined_: _C. occidentalis californicus_, one from Mary's +Peak, Benton Co., Oregon, 30, F. W. Sturges' collection. + + +Clethrionomys glareolus Schreber + +Fig. 13 + +Baculum: Stalk elongate, greatest length (2.9 mm.) twice the greatest +breadth in the specimen examined, flattened proximally, greatest length +almost 6 times greatest depth of base; three well-developed ossified +processes; median process arched in a dorsoventral plane, with basal +notch and lateral lobes; lateral processes as long as median process, +bowed in dorsal view, flattened distally, with ventromedial vane; basal +tuberosities of stalk weakly developed, medially confluent; posterior +profile in dorsal view evenly rounded; in end-view dorsal concavity +shallow in comparison to most species but deeper than ventral concavity, +constriction 3/4 greatest depth; shaft straight, at mid-point slightly +wider than high, elongate, widest point of stalk less than 1/4 of total +length from proximal end, slight lateral inflation at tip; lateral +profile in dorsal view sloping at first abruptly and then gradually from +widest point of stalk anteriorly onto shaft. + +The specimen of _Clethrionomys glareolus_ figured by Ognev (1950:31) in +dorsal view as I interpret it, resembles my specimen in the rounded base; +in the elongate, distally inflated shaft; in the initially abrupt slope +of the lateral profile in dorsal view from the greatest width of stalk +anteriorly; and in the presence of three well ossified processes. Ognev's +specimen differs from mine in the median process being more elongate +relative to its width, and rounded proximally, lacking lateral lobes and +basal notch; in lateral processes being less curved; in the greater +terminal inflation of the shaft; and in the closer approximation of the +terminal processes to the shaft. The baculum of _Clethrionomys glareolus_ +as described and figured by Didier (1954:243-244) resembles my specimen +in general proportions, but is more pointed proximally and more curved in +dorsoventral plane. Didier states that the baculum is rather variable in +form in this species, in different regions, but that a large number of +specimens must be examined to assess the geographic nature of this +variation. + +_Specimen examined_: One from Zermatt, Valais, Switzerland, 67100. + + +Clethrionomys rufocanus Sundevall + +Fig. 9 + +Baculum: Base of stalk broad but relatively flattened dorsoventrally, +greatest length (3.2 mm.) less than 1-1/2 greatest width, 4 times +greatest depth; three well-developed ossified processes; median process +arched in dorsoventral plane, having basal notch and lateral lobes; +lateral processes as long as median process, flattened distally, with +ventromedial vane; basal tuberosities of stalk weakly developed, medially +confluent; posterior profile in dorsal view convex with rounded posterior +apex; dorsal surface of base almost flat, ventral concavity broad and +shallow; constriction 3/4 greatest depth (not including an unusual +irregularity on the ventral surface of the base); shaft straight, at +mid-point of stalk distinctly wider than high, slender at distal end, +widest point of stalk almost 1/3 of total length from proximal end, tip +of shaft rounded; lateral profile in dorsal view gradually sloping from +widest point anteriorly onto shaft. + +The specimen of _Clethrionomys rufocanus_ figured by Ognev (1950:97) +resembles my specimen in the presence of three well ossified processes. +Ognev's specimen differs however in the lack of a proximal notch on the +median process, the lesser proportion of the stalk included in the basal +enlargement, the more posterior position of the point of greatest width, +and the presence of a concavity in the posterior profile of the stalk in +dorsal view. These differences in the stalk may be owing to a difference +in age (my specimen perhaps being older). + +_Specimen examined_: One from 1 mi. NW Oho-ri, 6 M., Korea, 60438. + + +Phenacomys intermedius Merriam + +Figs. 7 and 8 + +Baculum: Stalk slender, greatest length (2.9 mm.) 2-1/4 to 2-1/2 times +greatest breadth, 4 times greatest depth; three well-developed ossified +processes, median one almost 1/2 length of stalk, curved, broad basally +and slightly larger in all dimensions than either lateral process; +lateral processes flattened distally, curved; base of stalk well +developed, basal tuberosities medially confluent or separated by medial +emargination, posterolateral faces flattened or rough; emarginations in +the four adults examined; posterior profile in dorsal view bluntly +pointed or flattened except for emargination posterially, abruptly curved +at point of greatest width; shaft arising broadly from distal side of +base of stalk; in end-view hour-glass shaped, medial constriction +pronounced, both dorsal and ventral concavities deep; shaft having +relatively straight but distally convergent sides; at mid-point of stalk, +1 to 1-1/2 times as wide as deep; tip bluntly rounded, or slightly +inflated. + +The specimens from Quebec differ from the one from Wyoming in smaller +size, relatively smaller lateral digital processes, larger more medial +basal emargination, and slender shafts. The baculum of _Phenacomys +intermedius_ differs much from that of _Phenacomys longicaudus_, +described by Hamilton (1946:381) and by Dearden (1958:547). Dearden +states that the three bacula examined by him of _Phenacomys longicaudus_ +differ markedly from the specimen described by Hamilton. It seems to me +that in major features the resemblance is greater between the specimens +of _Phenacomys longicaudus_ examined by these two authors than between +their specimens and specimens of other microtines, including _Phenacomys +intermedius_. Neither Hamilton nor Dearden record the exact localities of +capture, the collections in which the specimens are deposited, or the +catalogue numbers of specimens. Consequently verification of +identifications and observations is difficult. + +_Specimens examined_: Five, of two subspecies; _P. intermedius +intermedius_, 5.4 mi. S Moran, Teton Co., Wyoming, 3-C-309, collection of +W. B. Quay; _P. intermedius celatus_, four (including one immature +specimen) from Authiernord, Abitibi-ouest Co., Quebec, specimens in +collection of Bristol Foster designated by numbers 2041-2044 of S. +Anderson's field catalogue. Smith and Foster (1957:107) were of the view +that _Phenacomys ungava_ (including the above specimens from Quebec) may +be specifically distinct from _Phenacomys intermedius_. + + +Ondatra zibethicus (Linnaeus) + +Not figured + +Baculum: In the single specimen examined, less mature than that figured +by Hamilton (1946:384), the digitate processes are cartilaginous, the +basal tuberosities are less well developed, and the shaft is slenderer +throughout. The cartilaginous processes are of the same proportions as +ossified processes in the figure mentioned. The shaft is also convex +ventrally in lateral profile. The view of the side here considered to be +anatomically the ventral side (adjacent to the urethra) is labelled +dorsal view in Hamilton's specimen. + +_Specimen examined_: One, from Reserve, Brown Co., Kansas, 72405. + + +Microtus (Herpetomys) guatemalensis Merriam + +Figs. 42 and 43 + +Baculum: Stalk moderately elongate, greatest length (3.5 mm.) 2-1/3 times +greatest breadth, spatulate, flattened throughout, greatest thickness 1/3 +millimeter; three ossified processes; median process having three +cornered base, curved dorsally, wider than high, 1/4 to 1/5 greatest +length of stalk; each lateral process bent at middle, as long as median +process, compressed laterally; base of stalk curved dorsally, +tuberosities marginal, hence narrow, lateral excavations of tuberous +margin not confluent medially; in end-view ventral concavity broad, no +dorsal concavity, medial constriction but slightly less than greatest +thickness (not depth); shaft wider than high throughout, at mid-point +more than 3 times as wide as high; tip of shaft slightly inflated both +laterally and dorsoventrally; lateral profile gradually sloping +anteriorly from widest point of stalk. + +Specimen number 65921 (Fig. 43) differs from number 65895 (Fig. 42) +described above. Terminus of shaft of number 65921 has lateral lobes from +which arise lateral cartilaginous processes; median terminal ossification +irregular in shape, smaller, imbedded in terminally bilobate cartilage. +In the spatulate flattened stalk these two specimens are much alike. An +immature specimen, number 65908, is smaller (length of stalk 2.6 mm.) +also flattened and spatulate, has the terminal processes cartilaginous, +the lateral processes bent medially, and proportions as in the adult. + +The baculum shows no noteworthy resemblance to that of any other species +of North American _Microtus_; on the other hand the differences between +_M. guatemalensis_ and some other species are no greater than the +differences between certain species included in the subgenus _Microtus_. +The baculum neither strengthens nor weakens the case for subgeneric rank +for _M. (Herpetomys) guatemalensis_. + +_Specimens examined_: Three from Guatemala; 65895 (2 mi. S San Juan +Ixcoy), 65908, (3-1/2 mi. SW San Juan Ixcoy), 65921 (10 mi. E, 4 mi. S +Totonicapán). + + +Microtus (Arvicola) richardsoni (DeKay) + +Figs. 38 and 39 + +Baculum: Stalk broad, greatest length (3.7 to 4.3 mm.) 1-1/2 times +greatest breadth, relatively flattened, greatest depth 1/3 greatest +breadth; single median ossified process, in smaller of two specimens this +ossification incomplete and of unusual shape (Fig. 39); length of stalk 4 +times length of median process; concavities of basal tuberosities +medially confluent, constriction less than 1/2 greatest depth; widest +point of shaft less than 1/4 length of shaft from posteriormost point; +shaft wider than high except at distal end that is inflated dorsally and +sometimes laterally; both ventral and dorsal concavities of base of stalk +broad and moderately deep; posterior profile in dorsal view evenly +rounded or having marginal notch. + +In the absence of ossified lateral processes my two specimens differ from +bacula of _Microtus (Arvicola) terrestris_ figured by Didier (1943:79, +1954:245, 247, 248) and by Ognev (1950:591). The median process relative +to the size of the shaft is smaller, and the shaft relative to its length +is wider in _M. richardsoni_ than in _M. terrestris_. The stalk of _M. +(Arvicola) amphibius_ figured by Didier is like that of _M. richardsoni_ +in its greater breadth and median notch on posterior border. + +The relationship of the New World water rat, _M. richardsoni_, to the Old +World water rats (genus _Arvicola_ of some European authors) is +uncertain. Miller (1896:66) placed all of them in the subgenus +_Arvicola_. Subsequent authors, stressing differences in the teeth, have +placed _M. richardsoni_ in the subgenus _Aulacomys_ of Rhoads. Zimmerman +(1955) has shown that teeth in some _Arvicola_ approach the more complex +pattern of _M. richardsoni_. He argues also that _Arvicola_ is +generically distinct from _Microtus_ on the grounds that the two groups +have separate origins, _Arvicola_ having descended from the genus +_Mimomys_ and _Microtus_ from some other group of microtines. This +argument also was advanced by Hinton (1926:47-48). Pending further +studies of the possible polyphyletic origin of other subgenera of the +genus _Microtus_, I refer both _M. richardsoni_ and _M. terrestris_ to +the subgenus _Arvicola_. + +The evidence afforded by the bacula available is not conclusive as to +relations of Old World and New World water rats. No general agreement on +the number of species in this Palaearctic group has been reached, and +bacula of only three or four of the numerous Old World subspecies have +been figured. I have examined none. + +_Specimens examined_: Two, from Wyoming; 42454 (31 mi. N Pinedale, 8025 +ft., Sublette Co.), 37903 (23-1/2 mi. S, 5 mi. W Lander, 8600 ft., +Fremont Co.). + + +Microtus (Chilotus) oregoni (Bachman) + +Fig. 45 + +Baculum: Stalk broad, greatest length (2.2 mm.) 1-3/4 times greatest +breadth, 3-1/2 times greatest depth; three well-developed ossified +processes; median process 2/5 length of stalk, rounded or tapered +terminally, proximal end opposed to tip of stalk and flattened obliquely; +lateral processes 2/3 length of median process, deeper than wide, curved; +tuberosities of stalk well developed, confluent medially, visible in +dorsal view; in end-view dorsal concavity narrow, moderately deep, +rounded, ventral concavity wide, deep, flattened; base wider ventrally +than dorsally; shaft tapering more or less uniformly, terminally +inflated. + +In the relative sizes, to each other and to the stalk, of the three +digitate ossifications _M. oregoni_ resembles closely the Old World +representative of the same subgenus, _M. (Chilotus) socialis_, as figured +by Argyropulo (1933b:181). In _M. oregoni_ the greatest width of the +baculum is more proximal on the stalk than in the _M. socialis_ figured +by Argyropulo but closely resembles the baculum of the _M. socialis_ +figured by Didier (1954:242). In possessing a shallow emargination in the +base of the stalk and in possessing a median process that is smaller than +the lateral processes, _M. socialis_, as figured by Didier, differs from +_M. oregoni_. The baculum figured by Argyropulo (_loc. cit._) of +_Sumeriomys colchicus schidlovskii_ [ = _Microtus (Chilotus) socialis +schidlovskii_ according to Ognev, 1950:392] differs from other _Chilotus_ +that have been studied in having an unusually elongate median process and +a more distal placement of the widest part of the stalk. + +_Specimens examined_: Three, of the subspecies _M. oregoni oregoni_, from +5 mi. N Orick, Humboldt Co., California, 3-C-248, collection of W. B. +Quay; from Mary's Peak, Benton Co., Oregon, 66, collection of F. W. +Sturges; and from Sec. 3, T. 11S, R. 5W, Benton Co., Oregon, 79183. + + +Microtus (Stenocranius) gregalis (Pallas) + +Fig. 34 + +Baculum: Length of stalk (2.4 mm.) 1-3/4, times greatest breadth, 4-1/3 +times greatest depth; median ossified process well developed, more than +1/3 length of stalk, higher than wide, slightly bowed, closely appressed +to terminus of shaft; basal tuberosities of stalk moderately developed, +confluent medially, posterior profile of medial apex rounded in dorsal +view, lateral indentations present, hence trilobate outline; in proximal +end-view base wider ventrally, ventral concavity broader than dorsal +concavity but of equal depth, medial constriction 2/3 greatest depth; +shaft slender in distal part, inflated terminally, and wider than high at +mid-point of stalk; lateral profile a smooth slope of gradually +decreasing curvature from point of greatest width to near distal end. + +The baculum of this species figured by Ognev (1950:461) differs in having +lateral ossified processes, and a more rounded base of the stalk. +Resemblance to the New World _Stenocranius_ is discussed below. + +_Specimen examined_: One from "Eastern Europe," 8059. + + +Microtus (Stenocranius) miurus Osgood + +Figs. 32 and 33 + +Baculum: Length of stalk (2.8 mm.) 1-1/2 times greatest breadth, 3-1/2 +times greatest depth; median process ossified, 2/5 to 3/5 length of +stalk, laterally compressed, sometimes arched in dorsoventral plane; +lateral processes cartilaginous, slender; basal tuberosities well +developed, averaging less enlarged than shown in Figure 32, but more +angular in lateral outline than shown in Figure 33; tuberosities +confluent posteriorly; posterior profile smoothly rounded to trilobate, +curvature at point of greatest breadth usually acute; in proximal +end-view base wider dorsally, deep dorsal concavity, shallow ventral +concavity, medial constriction 3/5 of greatest depth; shaft slender +anteriorly, at mid-point of stalk twice as wide as high, at tip higher +than wide, laterally inflated; lateral profile in most specimens abruptly +curved anterior to point of greatest breadth. + +The single specimen of the Old World _M. (Stenocranius) gregalis_ +examined resembles the New World _M. (Stenocranius) miurus_ in the +angular lateral profile at the point of greatest breadth of the stalk, +slender shaft in comparison to broad base of stalk, and presence of a +single well-developed laterally compressed median process. The base of +the stalk in the baculum of _M. gregalis_ is less well developed and +smaller than in the baculum of _M. miurus_. + +_Specimens examined_: Nine, all of the subspecies _Microtus miurus +muriei_, from the Brooks Range, Alaska; 51077 (Lake Schrader, 145°09'50", +69°24'28", 2900 ft., Romanzof Mts.); 51151, 51152, 51154, 51164, 51166, +51169 (last 6 from Wahoo Lake, 69°08', 146°58', 2350 ft.); 51210, 51213 +(last 2 from Porcupine Lake, 68°51'57", 146°29'50", 3140 ft.). + + +Microtus (Chionomys) nivalis Martins + +Fig. 47 + +Baculum: Greatest length of stalk (2.7 mm.) 2-1/4 times greatest breadth, +4-1/2 times greatest depth; three digitate processes, lateral processes +mostly cartilaginous in single adult examined; median process well +ossified, approximately 1/3 length of stalk, basally notched, not arched, +laterally compressed distally; base of stalk broad and flat, basal +tuberosities well developed, separate; posterior profile in dorsal view +rounded, convex except for medial notch separating tuberosities; dorsal +and ventral concavities deep, broad, equal; medial constriction less than +1/2 greatest depth; in dorsal view shaft tapering gradually from widest +point, terminally rounded; at mid-point of stalk almost twice as wide as +high. + +In the elongate, largely cartilaginous lateral processes of the baculum, +the specimen described above resembles _M. longicaudus_. The size of the +median process in comparison to the size of the stalk is also the same. +The lateral processes have larger ossifications and the base of the stalk +is more robust in _M. longicaudus_ than in _M. nivalis_. + +The well ossified lateral processes and enlarged base of Didier's +(1954:240) specimen suggest that it is of a more mature individual than +the one described above. These specimens of _M. nivalis_, as well as the +specimens of _M. longicaudus_, exhibit dorso-ventral flattening of the +mid-part of the base of the stalk. + +The baculum of a specimen from Switzerland is weakly developed, of small +size (shaft 2.0 mm. in length), slender, thin, spatulate, and terminally +inflated. Digital processes were not observed, perhaps owing to excessive +maceration in preparation. The general appearance of the baculum is that +of an immature individual, although the animal was not small (165 mm. +total length in preservative). + +_Specimens examined_: Two _Microtus nivalis nivalis_; Zermatt, Valais, +Switzerland, 67105; Wetterstein, Germany, 65127. + + +Microtus (Chionomys) longicaudus (Merriam) + +Fig. 48 + +Baculum: Base of stalk well developed, greatest length (3 mm.) 1-3/4 +times greatest breadth, 3-2/3 times greatest depth; three ossified +processes; base of median process rounded; median process slightly curved +in dorsoventral plane, in length almost 1/3 greatest length of stalk; +ossifications in lateral processes variable in size, frequently widely +separated from shaft by cartilage, rarely as large as median +ossification; basal tuberosities usually well-developed, medially +confluent; profile of base in dorsal view trilobate or irregularly convex +throughout; constriction 1/2 greatest depth; shaft relatively straight or +slightly bowed ventrally or dorsally, shaft at mid-point of stalk wider +than high; tip of shaft laterally inflated; widest point of stalk +approximately 1/4 length of stalk from proximal end; lateral profile in +dorsal view tapers gradually onto shaft anteriorly from point of greatest +width of stalk; shaft variable, from slender terminally and nearly +parallel sided (Fig. 48), to broad distally and tapered. + +In many of the features that distinguish _M. longicaudus_ (and the +closely related insular species _M. coronarius_) from other North +American _Microtus_, _longicaudus_ resembles the Old World species of the +subgenus _Chionomys_ (that is to say, _M. nivalis_, _M. gud_, and _M. +roberti_). These features are medium size, long tail, grayish color, +montane habitat, relatively short molar tooth-row, moderate sized and +unconstricted incisive foramen, relatively decurved upper incisors, +elongate nasals, relatively broad interorbital region without +well-developed median ridge, and similar chromosomes (Matthey, 1955:178). +For these reasons I am here referring _Microtus longicaudus_ to the +subgenus _Chionomys_; previously it has not been referred to that +subgenus. + +_Specimens examined_: Six, of three subspecies; _Microtus longicaudus +littoralis_, Sullivan Island, Alaska, 42972, 42969; _M. l. mordax_, 3/4 +mi. N, 2 mi. W Allenspark, 8400 ft., Boulder Co., Colorado, 50335, 76829; +_M. l. sierrae_, Crane Flat, Mariposa Co., California, 50252, 50253. + + +Microtus arvalis (Pallas) + +Fig. 22 + +Baculum: In the single specimen examined, stalk small, greatest length +(2.3 mm.) 2-1/3 times greatest width, almost 6 times greatest depth, +flattened proximally; three well-developed digitate processes, the median +one ossified, the lateral processes cartilaginous; median ossification +laterally compressed and decurved at tip, bilobate at base; basal +tuberosities of stalk weakly developed, medially confluent; posterior +profile in dorsal view evenly rounded; ventral concavity deeper and +narrower than dorsal concavity, but both comparatively shallow; medial +constriction 2/3 greatest depth; shaft straight, at mid-point twice as +wide as deep; lateral profile tapering from greatest width gradually to +parallel sides of distal third of stalk. + +From the baculum of _Microtus arvalis_ figured by Ognev (1950:173), and +from the baculum figured by Didier (1954:238) my specimen differs in the +absence of lateral ossifications in the digitate processes, smaller and +slenderer median ossification, and weaker base. These differences in part +may be owing to a difference in age, my specimen being the less mature. + +_Specimen examined_: One from Vidy, Switzerland, 67101. + + +Microtus orcadensis Millais + +Fig. 24 + +Baculum: In the one specimen examined, stalk broad, greatest length (2.6 +mm.) 1-1/2 times greatest breadth, 3-1/2 times greatest depth; three +digitate processes ossified; median process relatively broad, in length +more than 1/2 length of stalk, triangular in dorsal view, with small +spurs posterolaterally, middorsal ridge posteriorly; lateral +ossifications slightly curved, slenderer, less than 1/2 depth and less +than 1/2 transverse thickness of median process; basal tuberosities +well-developed, confluent medially; in end-view base wider dorsally than +ventrally, dorsal concavity broader and more abruptly curved at mid-point +than ventral concavity; constriction 1/2 greatest depth; posterior +profile in dorsal view notched, setting off a posterior shelf; stalk +including shaft wider than deep throughout, at mid-point width twice +depth; lateral profile abruptly curved anterior to point of greatest +width, sides of shaft tapering gradually anteriorly to rounded uninflated +tip. + +The baculum of this insular species, placed in the "_arvalis_" group by +Ellerman (1941:595), resembles the baculum of both _Microtus agrestis_ +and _Microtus guentheri_ more than it resembles the baculum of _Microtus +arvalis_. Similarities in the chromosomes of _M. arvalis_ and _M. +orcadensis_ were noted by Matthey (1953:254, 279), who was of the opinion +that _M. orcadensis_ is an insular derivative of the _arvalis_-group. + +_Specimen examined_: One from the Orkney Islands, 67106. + + +Microtus guentheri Danford and Alston + +Fig. 23 + +Baculum: In the one specimen examined, stalk broad, greatest length (2.9 +mm.) 1-1/2 times greatest breadth, 3-1/2 times greatest depth; three +digitate processes ossified; median process slightly less than 1/2 length +of stalk, broad, dorsally curved; curved lateral ossifications shorter +and more slender than median ossification; basal tuberosities well +developed, angular, confluent across posterior border of projecting +shelf; in end-view tuberosities projecting ventrolaterally from central +shelf; dorsal surface at medial constriction flat, ventral surface +broadly and deeply concave; posterior profile in dorsal view trilobate, +central lobe formed by posteriorly flattened shelf, surface of attachment +visible only on lateral lobes; at mid-point stalk almost twice as wide as +deep, depth of shaft greater than width proximal to inflated terminus. + +_Specimen examined_: One from Palestine, 67104. + + +Microtus fortis Büchner + +Fig. 25 + +Baculum: Stalk large, greatest length (3.8 mm.) 1-4/5 times greatest +breadth, 4-1/2 times greatest depth; three digitate processes ossified; +median ossification almost 1/3 length of stalk; lateral ossifications +slender, smaller than median ossification; posterior profile of stalk in +dorsal view trilobate, basal tuberosities well developed, confluent +medially; in end-view dorsal concavity broader and deeper than ventral +concavity; medial constriction pronounced (less than 1/2 greatest depth); +lateral profile at widest point of stalk convex, becoming abruptly +concave as the flange of the basal tuberosities grades into the shaft, +then gradually converging to narrowest point 1/3 of length of stalk from +the terminus; stalk wider than deep in proximal 2/3, circular in cross +section in terminal 1/3, slight terminal inflation. + +A specimen figured by Ognev (1950:297) has the same general proportions, +slender lateral processes, and proximal placement of the point of +greatest breadth. + +_Specimens examined_: Two from Chipo-ri, Korea, 60443, 63841. + + +Microtus montanus (Peale) + +Figs. 19, 20 and 21 + +Baculum: Stalk broad, greatest length (varying with subspecies from 2.3 +to 3.1 mm.) 1-1/2 to 1-3/4 times greatest breadth, 3-1/3 to 4-1/3 times +greatest depth; three ossified processes, median one largest, more than +twice as wide and as deep as shorter, slenderer, lateral processes; +median process laterally compressed distally except in one specimen in +which moderately inflated distally, proximally enlarged in some specimens +(Fig. 21) and 1/3 to 2/5 length of stalk; base broad, posterior profile +in dorsal view evenly convex throughout, at widest point of stalk +abruptly incurved; basal tuberosities moderately to strongly developed, +medially confluent; in end-view base wider ventrally than dorsally, +dorsal concavity slightly to much deeper than the nearly flattened +ventral concavity; medial constriction 2/3 to 4/5 of greatest depth; +shaft relatively slender, at mid-point of stalk slightly wider than high +and 1/4 as wide as base of stalk, terminally rounded or slightly +inflated; lateral profile in dorsal view a gradual curve from point of +greatest width anteriorly onto shaft. + +The different subspecies figured show the essential characteristics of +the species, differing primarily in size. + +_Specimens examined_: Fourteen, of three subspecies; _Microtus montanus +amosus_, 1/2 mi. E Soldier Summit, Wasatch Co., Utah, 62241; _M. montanus +fusus_, La Manga Pass, Conejos Co., Colorado, 42164; 5 mi. N, 26 mi. W +Saguache, 9500 ft., Saguache Co., Colorado, 42307, 42315; 5 mi. N, 27 mi. +W Saguache, 9350 ft., Saguache Co., Colorado, 42308; 5 mi. N, 28 mi. W +Saguache, 9325 ft., Saguache Co., Colorado, 42309; 5 mi. S, 24 mi. W +Antonito, 9600 ft., Conejos Co., Colorado, 42327, 42330; Prater Canyon, +Mesa Verde National Park, Montezuma Co., Colorado, 69456, 69457, 69463; +_Microtus montanus nanus_, 2 mi. N, 2 mi. W Pocatello, Bannock Co., +Idaho, 57470, 57472; 3/4 mi. N, 2 mi. W Allenspark, 8400 ft., Boulder +Co., Colorado, 50330. + + +Microtus townsendii (Bachman) + +Fig. 41 + +Baculum: Stalk broad, greatest length (3.0 mm.) 1-1/2 times greatest +breadth, 4-1/2 times greatest depth; three ossified processes, median one +largest, deeper and more than twice as wide as curved, shorter, +compressed lateral processes and more than 2/5 as long as stalk; base +broad, in dorsal view posterior profile trilobate, basal tuberosities +visible; basal tuberosities well developed, medially confluent; in +end-view base wider ventrally than dorsally, dorsal concavity deeper than +ventral concavity; medial constriction 3/5 of greatest depth; shaft +broad, at mid-point more than twice as wide as high and 1/3 as wide as +base of stalk, terminally rounded. + +_Specimens examined_: Three, all _M. t. townsendii_; Fort Lewis, Pierce +Co., Washington, 57998, subadult; Sec. 33, T. 11S, R. 5W, Benton Co., +Oregon, 79186; Sec. 5, T. 12S, R. 4W, Benton Co., Oregon, 79188. + + +Microtus oeconomus (Pallas) + +Fig. 44 + +Baculum: Stalk broad and flattened, greatest length (3.5 mm.) 1-2/3 to 2 +times greatest width, 4 to 5-1/2 times greatest depth; three ossified +processes, median one largest, lateral processes slender, relatively +small; length of median process 3/8 length of stalk; median process +decurved, dorsoventrally flattened in some specimens, widened at base; +attachment of processes to shaft displaced ventrally; base of stalk +widened, posterior profile in dorsal view usually trilobate, in a few +cases rounded, median lobe forming posterior shelf, lateral lobes +dorsally raised and forming margins of lateral tuberosities; in end-view +thickness frequently more or less uniform throughout central part, broad +depression dorsally, ventral concavity narrower and shallower (as +figured); base, and occasionally shaft, flattened, width at mid-point of +stalk 2 to 3 times depth, narrowest point posterior to terminal inflation +of shaft in terminal 1/3 of shaft. + +The baculum of _M. oeconomus_ (Old World) figured by Ognev (1950:257) +resembles but exceeds that of _M. oeconomus_ (New World) in the +relatively large median process and slender lateral processes, but +differs noticeably in the presence of a deep median notch in the base of +the stalk. A specimen from Hungary is intermediate between Ognev's +specimen and those from the New World in both size of median process and +size of lateral processes, and has an unnotched base resembling that in +Figure 44. + +_Specimens examined_: Ten, of three subspecies; _M. oeconomus gilmorei_, +Umiat, Alaska, 51354, 51361, 51399, 51408; Lake Schrader, Brooks Range, +Alaska, 51422; _M. o. macfarlani_, 5 mi. NNE Gulkana, Alaska, 43039, +43041; 20 mi. NE Anchorage, Alaska, 43044; Kelsall Lake, British +Columbia, 43048; _M. o. mehelyi_, Kisbalatan, Hungary, 75159. + + +Microtus mexicanus (Saussure) + +Figs. 35 and 36 + +Baculum: Stalk attenuate, greatest breadth relatively near proximal end; +greatest length (3.1 to 3.4 mm.) more or less twice greatest breadth, 4 +to 5 times greatest depth; usually a single process ossified; lateral +processes relatively small, cartilaginous or (in three specimens, 63094, +69453, 68019) with small ossifications; median process relatively small, +sometimes appressed to tip of shaft, in length less than 1/4 length of +stalk; posterior profile in dorsal view rounded, flattened posteriorly, +or in some specimens trilobate with angular edges; in end-view relative +depths of dorsal and ventral concavities variable, dorsal usually deeper +than ventral; distal end of stalk frequently bowed dorsally; shaft +slender distally, sometimes slightly inflated terminally, or (in one +specimen, 63085) near tip small lateral projections that are perhaps +fused lateral ossifications; lateral profile in dorsal view a gradual +slope anteriorly from point of greatest width to slender tip. + +_Specimens examined_: Thirteen, of four subspecies; _Microtus mexicanus +mexicanus_, Las Vigas, Veracruz, 30692; Nevada de Toluca, México, 63101; +Valle de Bravo, México, 63094; _Microtus mexicanus mogollonensis_, Mt. +Taylor, Valencia Co., New Mexico, 63298, 76830; Park Well, Mesa Verde +National Park, Montezuma Co., Colorado, 69448, 69453; Upper Nutria, +McKinley Co., New Mexico, 69997, 70000; _Microtus mexicanus phaeus_, +Sierra Patamba, 9000 ft., Michoacán, 63085; _Microtus mexicanus +subsimus_, 2 mi. E Mesa de Tablas, Coahuila, 58916; 13 mi. E San Antonio +de las Alazanas, Coahuila, 68019, 68021. + + +Microtus californicus (Peale) + +Fig. 37 + +Baculum: Stalk elongate, greatest length (3.0 mm.) 2-1/3 times greatest +breadth, 4-1/2 times greatest depth; median process ossified, 1/4 length +of stalk, basally broadened, flattened and shallowly grooved ventrally to +fit tip of shaft, to which the process is closely appressed; lateral +processes cartilaginous; ends of stalk bowed upwardly; posterior profile +of base of stalk rounded or slightly trilobate if posterolateral +concavities form in tuberosities; moderate development of tuberosities, +in end-view dorsal concavity slightly deeper and narrower than ventral +concavity, both comparatively shallow, median constriction 4/5 greatest +depth; shaft curved, more or less terete at mid-point of stalk, +terminally inflated dorsally; lateral profile in dorsal view gradually +curved from point of greatest width anteriorly onto shaft. + +_Specimens examined_: Two, of two subspecies; _Microtus californicus +californicus_, 1 mi. NE Berkeley, in Contra Costa Co., California, 76828; +_Microtus californicus mohavensis_, 1/2 mi. SE Victorville, San +Bernardino Co., California, 63745. + + +Microtus pennsylvanicus (Ord) + +Figs. 14, 15, 16 and 17 + +Baculum: Stalk heavy, broad, greatest length (2.2 to 3.0 mm.) 1-1/3 to +1-2/3 times greatest breadth, up to 3-3/4 times greatest depth; three +ossified processes, median one largest, usually not twice so deep as +lateral ossifications; median process usually distinctly widened basally, +in length approximately 1/2 length of stalk; base broad, frequently +angular laterally and basally, sometimes bilobate; basal tuberosities +well developed, medially confluent; in end-view more or less uniformly +biconvex or ventral surface more flattened than dorsal surface, medial +constriction 1/2 to 2/3 greatest depth; shaft relatively heavy, at +mid-point stalk almost twice as wide as deep and 1/3 as wide as base of +stalk; shaft terminally rounded and sometimes slightly inflated; lateral +profile in dorsal view abruptly or gradually curved anterior to point of +greatest width and then gradually curved anteriorly. + +Specimens examined averaged slightly smaller and were more variable than +those described by Hamilton (1946:382). The greater variation may be in +part geographic, as five subspecies are represented. Lateral processes +are the last to ossify. One specimen (75082) with well-ossified median +process lacks any lateral ossification. Four bacula of _M. +pennsylvanicus_ (locality not specified) studied by Dearden (1958:547) +agree in general with the description above. + +One specimen shows a break, perhaps resulting from injury, in the shaft +(Fig. 14). One specimen has a posteromedian spine on the median digital +ossification (Fig. 16). Comparison with _M. agrestis_ is included with +the description of _M. agrestis_. + +_Specimens examined_: Thirteen, of six subspecies; _Microtus +pennsylvanicus alcorni_, 20 mi. NE Anchorage, Alaska, 43043; _Microtus +pennsylvanicus finitus_, Laird, Yuma Co., Colorado, 68544; _Microtus +pennsylvanicus modestus_, 5 mi. N, 26 mi. W Saguache, 9500 ft., Saguache +Co., Colorado, 42306; 3 mi. N, 16 mi. W Saguache, 8500 ft., Saguache Co., +Colorado, 42416, 42417, 42418; 1 mi. S, 2 mi. E Eagle Nest, 8100 ft., +Colfax Co., New Mexico, 42430, 42439; _Microtus pennsylvanicus +pennsylvanicus_, 2 mi. S, 3 mi. E Ft. Thompson, 1370 ft., Buffalo Co., +South Dakota, 42379; Vermillion, Clay Co., South Dakota, 37070; _Microtus +pennsylvanicus pullatus_, 12 mi. S, 5 mi. E Butte, Silver Bow Co., +Montana, 57501, 57503; _Microtus pennsylvanicus uligocola_, Muir Springs, +2 mi. N, 2-1/2 mi. W Ft. Morgan, Morgan Co., Colorado, 75082. + + +Microtus agrestis (Linnaeus) + +Fig. 18 + +Baculum: Greatest length of stalk (2.9 mm.) twice greatest breadth, 4-1/2 +times greatest depth; stalk well developed, shaft not flattened +dorsoventrally; large median ossified process, minute lateral +ossifications in single specimen examined; length of stalk 2-1/2 times +length of median ossification which is higher than wide, slightly +decurved, sagittate in dorsal view, with three-cornered base; basal +tuberosities of stalk moderately well developed, medially joined; +posterior profile in dorsal view evenly rounded; ventral concavity +broader than, but of comparable depth to, dorsal concavity in end-view, +base of stalk wider ventrally, constriction 3/4 greatest depth; at +mid-point of stalk shaft is but slightly wider than high; pronounced +terminal inflation of shaft; lateral profile in dorsal view sloping +abruptly from widest point of stalk anteriorly onto stalk which then +tapers more gradually to terminal inflation. + +From the baculum of its New World counterpart, namely _Microtus +pennsylvanicus_, my specimen of _Microtus agrestis_ and the specimen +figured by Didier (1954:239) differ in their minute lateral processes, +relatively larger median processes, and more elongate, less +dorsoventrally flattened shafts. + +The specimen of _M. agrestis_ figured by Ognev (1950:320), in dorsal view +has lateral concavities producing a somewhat trilobate outline in the +base of the stalk, and the lateral processes are well developed; the +median process is larger and bulbous, wider distally than proximally. +Without larger numbers of bacula of _M. agrestis_ I am unable to +reconcile these differences. The differences between _M. agrestis_ and +_M. pennsylvanicus_ seem comparable to the differences between some other +species of _Microtus_. + +_Specimen examined_: One, from Gryon, Switzerland, 67102. + + +Microtus (Pedomys) ochrogaster (Wagner) + +Fig. 31 + +Baculum: Stalk broad, greatest length (3.2-4.0 mm.) 1-2/3 to 2 times +greatest breadth, 2-1/2 to 4 times greatest depth; median process +ossified, relatively small, less than 3/10 length of stalk; lateral +processes arising from subterminal part of stalk, cartilaginous or with +small ossifications; posterior profile in dorsal view broadly rounded or +slightly angular, widest point of stalk 1/6 to 1/4 the length of stalk +from base; basal tuberosities well developed and medially confluent, in +end-view dorsally convex, or at least less deeply concave than ventrally; +shaft straight, base bent ventrally or more commonly dorsally; at +mid-point of stalk wider than high, often twice as wide as high; viewed +from above, lateral profile from point of greatest breadth to middle of +shaft a gradual sigmoid curve; slight terminal inflation of shaft. + +_Specimens examined_: Forty-one, of three subspecies; _Microtus +ochrogaster haydeni_, Muir Springs, 2 mi. N, 2-1/2 mi. W Ft. Morgan, +Morgan Co., Colorado, 74995, 74998, 74999, 75002; 1 mi. W Laird, Yuma +Co., Colorado, 57304, 76833; 2 mi. N, 2 mi. W Haigler, Dundy Co., +Nebraska, 75016; 2 mi. S Franklin, Franklin Co., Nebraska, 75043, 75044; +Atwood, Rawlins Co., Kansas, 75020, 75023, 75025, 75027, 75028; 1 mi. N, +2 mi. E Oberlin, Decatur Co., Kansas, 75030, 75032, 75034, 75035, 75036; +1-1/2 mi. N, 1/4 mi. E Norton, Norton Co., Kansas, 68327; 1 mi. SW +Norton, Norton Co., Kansas, 75037; 2 mi. S, 1 mi. W Norton, Norton Co., +Kansas, 75038; _M. ochrogaster ochrogaster_, Rydal, Republic Co., Kansas, +75047-75053, 75060, 75062, 75063, 75066, 75070, 75071, 75073; 1 mi. N, 1 +mi. W Holton, Jackson Co., Kansas, 75077; 2 mi. W Court House, Lawrence, +Douglas Co., Kansas, 76832; Univ. Kansas Natural History Reservation, +Douglas Co., Kansas, 68536; _M. ochrogaster taylori_, Meade County State +Park, Kansas, 68539, 68542. + + +Microtus (Pitymys) pinetorum (LeConte) + +Figs. 27 and 28 + +Baculum: Stalk broad, greatest length (2.5 to 2.7 mm.) 1-2/3 times +greatest breadth, 4 times greatest depth; median process ossified, size +small, 1/5 length of stalk, higher than wide, having small anterodorsal +prominence in both specimens examined; lateral processes cartilaginous, +relatively small, displaced posteriorly, attenuate; posterior margin in +dorsal view broadly rounded, or having blunt median apex, convex +throughout; basal tuberosities moderately well developed, medially +confluent, barely visible in dorsal view when mature; in end-view median +constriction 4/5 greatest depth, ventral concavity deeper than dorsal +concavity, both comparatively shallow; stalk at mid-point 1-1/2 times as +wide as deep; shaft relatively slender, bowed dorsally at tip, relatively +straight otherwise; lateral profile in dorsal view a gradual concave +slope from point of greatest width anteriorly to distal part of shaft. + +_Specimens examined_: Two, from Douglas Co., Kansas, 76834 (2 mi. N +Baldwin), 68545 (1 mi. NE Pleasant Grove). + + +Microtus (Pitymys) parvulus (Howell) + +Fig. 40 + +Baculum: Stalk broad, greatest length (2.4 mm. in specimen examined) +1-3/4 times greatest breadth, 4 times greatest depth; median process +ossified, size small, less than 1/4 length of stalk, wider than high, +terminally flattened; lateral processes cartilaginous, relatively small, +attenuate; posterior margin in dorsal view flattened, irregularly curved +with concavities medially and laterally; basal tuberosities well +developed, medially confluent; visible in dorsal view; in end-view median +constriction 2/3 greatest depth, ventral concavity well-formed, no dorsal +concavity; stalk at mid-point twice as wide as deep; shaft relatively +slender, bowed dorsally toward tip; in dorsal view lateral profile a +gradual concave slope from point of greatest width anteriorly to distal +part of shaft; tip of shaft enlarged. + +The baculum of _M. parvulus_ resembles that of _M. pinetorum_ more than +it resembles the baculum of any other microtine studied, differing +primarily in smaller size. + +_Specimen examined_: One, from 1 mi. W Micanopy, Alachua Co., Florida, +Univ. Florida No. 1508. + + +Microtus (Pitymys) quasiater (Coues) + +Figs. 29 and 30 + +Baculum: Stalk broad, greatest length (2.6-3.2 mm.) 1-1/3 to 1-2/3 times +greatest breadth, 3-1/3 to 3-2/3 times greatest depth; median process +ossified, with ventral depression, process 1/4 to 1/3 length of stalk, +appressed to tip of shaft, wider than high proximally, relatively broad +terminally; lateral processes cartilaginous, small, attenuate; posterior +profile of stalk in dorsal view broadly rounded, bilobate, or trilobate, +median lobe formed by posterior projection of dorsal shelf between +enlarged lateral tuberosities that form outer lobes, posterolateral faces +of these tuberosities visible in dorsal view of stalk; in end-view dorsal +surface slightly concave, ventral concavity broad and deep, median +constriction 1/2 greatest depth; shaft flattened except tip that is more +terete, and bowed dorsally; at mid-point, stalk twice as wide as high; +shaft relatively slender terminally, narrower than median ossification. + +The baculum of _M. quasiater_ is the largest and has the best developed +base and median process of the three American species of the subgenus +_Pitymys_. The three species closely resemble each other in basic form. + +_Specimens examined_: Five, all from Veracruz; Teocelo, 4500 ft., 30709, +30711; 4 km. N Tlapacoyán, 1700 ft., 24466; 5 km. N Jalapa, 4500 ft., +19869, 19878. + + +Microtus (Pitymys) fatioi (Mottaz) + +Fig. 26 + +The baculum of a single specimen (KU 67103) of _M. fatioi_ from Zermatt, +Valais, Switzerland, was examined. The baculum is immature, as evidenced +by its small size, slender stalk and absence of ossified processes, +therefore no characterization is included. + +The baculum of another Old World species of the subgenus _Pitymys_, _M. +pyrenaicus_ from France, figured and described by Didier (1954:242-243), +differs from all New World _Pitymys_ examined in processing ossified +lateral processes. + +The status of _Pitymys_, as a genus or as a subgenus, is uncertain. Hall +and Cockrum (1953:448) considered the North American _Pitymys_ and +_Pedomys_ as subgenera of _Microtus_. They did not state specifically the +basis for this point of view, but mention the fact that these two +subgenera (_Pitymys_ and _Pedomys_) closely resemble each other +cranially. These authors did not study nor comment upon the status of the +Old World _Pitymys_. It may be asked whether the Old World and New World +_Pitymys_ have developed as fossorial _Microtus_ independently, or from +an ancestor common to both groups and not common to any other _Microtus_. +Matthey (1955:202) found 62 chromosomes (2N) in both the New World +_Pitymys pinetorum_ and the Old World _Pitymys duodecimcostatus_. This +suggests, but does not prove, common ancestry. + + +Neofiber alleni True + +Fig. 49 + +Baculum: Stalk massive, greatest length (4.7 mm.) 1-3/4 times greatest +breadth, 4 times greatest depth; ossification in digitate processes +variable; in one (KU 27123) of two specimens examined lateral processes +ossified and median process unossified, as in two specimens examined by +Hamilton (1946:379) from "southern Florida"; in my other specimen (KU +27268) that is possibly more mature, median process ossified although +less deeply stained than lateral ossifications or stalk; posterior +profile in probable dorsal view roughly rounded; in end-view probable +dorsal concavity deep, ventral concavity broad but shallow, and with +center convex; median constriction 3/5 greatest depth; shaft heavy, least +depth 2/3 greatest depth of base; stalk, at mid-point, slightly wider +than deep and more than 1/3 width of base; lateral profile in dorsal view +sharply incurved distal to point of greatest breadth, shaft therefore +relatively distinct from basal part of stalk; slight subterminal +constriction; tip less reduced in the two specimens examined than in two +figured by Hamilton. In preparation, the tissues that make it possible to +distinguish with certainty the dorsal and ventral surfaces of the baculum +were removed in both specimens. + +_Specimens examined_: Two, of the subspecies _Neofiber alleni alleni_, 2 +mi. S Gainesville, Alachua Co., Florida, 27268; 1 mi. E Courtenay, +Merritt Island, Brevard Co., Florida, 27123. + + +Lagurus curtatus (Cope) + +Fig. 46 + +Baculum: Stalk slender, greatest length (2.5 mm.) 2 to 2-2/3 times +greatest breadth, 4 to 5 times greatest depth; three ossified processes; +median one more than 1/3 length of stalk, curved dorsally toward tip, +proximally flattened and having acute lateral angles in dorsal view, +wider than deep except in distal half; lateral processes smaller than +median one, slenderer, shorter, of approximately same depth, also curved +dorsally; base of stalk well developed, basal tuberosities medially +confluent, in part visible in dorsal view, in end-view wider ventrally +than dorsally, dorsal and ventral concavities of equal depth and both +wide, medial constriction 1/2 greatest depth; posterior profile in dorsal +view broadly bilobate; lateral profile with abrupt transition from basal +tuberosities to gradually converging, slightly curved sides of shaft; +shaft terminally inflated. + +Dearden (1958:543) described and figured the bacula of six subspecies of +_Lagurus curtatus_ and two Asiatic species, _Lagurus lagurus_ and +_Lagurus luteus_. He examined at least 34 specimens of _L. curtatus_ and +found geographic variation in size, breadth of shaft distally, and +proportions of digital ossifications to each other and to the stalk. The +description that I have given above pertains to _L. c. levidensis_. + +The baculum of the Asiatic _Lagurus (Lagurus) lagurus_ figured by Ognev +(1950:554) agrees with that of _Lagurus (Lemmiscus) curtatus_, described +here, in the relatively elongate shaft and slender stalk, the proportions +of the processes, and the well-formed and moderately enlarged base of the +stalk. The bacula of three _Lagurus lagurus_ examined by Dearden +(1958:545) were of older individuals than the specimen that Ognev figures +and differ from it and from bacula of _Lagurus curtatus_ (all subspecies) +in the unusual, almost heart shaped, median process, and in larger size. +_Lagurus luteus_ examined by Dearden (1958:545) differs from both +_Lagurus lagurus_ and _Lagurus curtatus_ in lacking lateral digital +ossifications and in having shorter median digital ossifications and +wider base of stalk. + +_Specimens examined_: Seven _Lagurus curtatus levidensis_ from Wyoming; 9 +mi. S Robertson, Uinta Co., 26045, 26053; 8 mi. S, 2-1/2 mi. E Robertson, +Uinta Co., 26049; Farson, Sweetwater Co., 37906; 16 mi. S, 11 mi. W +Waltman, Natrona Co., 42457; 32 mi. S, 22 mi. E Rock Springs, 42465, +42466. + +The following key to the bacula in some adult North American Microtinae +is intended to help point out some of the most important differences. It +should be noted that not all species can be keyed out on the basis of the +baculum. The most difficult group in this respect includes the species of +_Microtus_ that have small or no ossified lateral processes, especially +species of the subgenera _Pedomys_ and _Pitymys_, and the two species +_Microtus californicus_ and _Microtus mexicanus_ of the subgenus +_Microtus_. Another complicating factor is the variability of bacula +evident in some species even in the small samples available. It is to be +expected that additional specimens will show variations not yet observed. + + +KEY TO THE BACULA OF SOME NORTH AMERICAN MICROTINES + + 1. Length of lateral digital ossifications more than 1/3 breadth + of stalk 2 + + 1´. Length of lateral digital ossifications less than 1/3 breadth + of stalk or absent 15 + + 2. Size small (total length of baculum less than 5.5 mm.) 3 + + 2´. Size large (total length of baculum more than 5.5 mm.) 14 + + 3. Width at mid-point of stalk more than 1/3 greatest breadth of + stalk 4 + + 3´. Width at mid-point of stalk less than 1/3 greatest breadth of + stalk, 8 + + 4. Stalk, viewed from proximal end hour-glass shaped, and width + of stalk less than 1/2 length of stalk.... _Phenacomys + intermedius_, p. 197 + + 4´. Stalk not both hour-glass shaped when viewed from proximal + end, and with width less than 1/2 length of stalk 5 + + 5. Shaft thin basally, thickness less than 1/3 of greatest breadth 6 + + 5´. Shaft thick basally, thickness 1/3 or more of greatest breadth 7 + + 6. Stalk more or less straight, base not deflected. _Microtus + oeconomus_, p. 204 + + 6´. Stalk spatulate, and base deflected from axis of shaft.... + _Microtus guatemalensis_, p. 198 + + 7. Base enlarged, depth nearly 1/2 of breadth.... _Lemmus + trimucronatus_, p. 193 + + 7´. Base moderately enlarged, depth near 1/3 of breadth.... + _Microtus pennsylvanicus_, p. 206, or _Microtus townsendii_, p. 204 + + 8. Base hour-glass shaped as viewed from proximal end.... + _Phenacomys intermedius_, p. 197 + + 8´. Not so 9 + + 9. Lateral processes separated from tip of shaft by more than the + thickness of the lateral process 10 + + 9´. Lateral processes separated from tip of shaft by less than the + thickness of the lateral process 11 + + 10. Lateral processes more than 1/2 the width of median + process.... _Microtus longicaudus_, p. 201 + + 10´. Lateral processes slender, less than 1/2 the width of median + process.... _Microtus montanus_, p. 204 + + 11. Lateral ossifications equal in length to median + ossification.... _Clethrionomys_, p. 194 + + 11´. Lateral ossifications shorter than median ossification 12 + + 12. Size small, less than 3.4 mm. in total length.... + _Microtus oregoni_, p. 199 + + 12´. Size medium, more than 3.4 mm. in total length 13 + + 13. Greatest width of stalk at a point about 1/3 of length of + stalk from base.... _Microtus chrotorrhinus_ (Hamilton, 1946:382). + + 13´. Greatest width of stalk at a point less than 1/3 of length of + stalk from base.... _Lagurus curtatus_, p. 210 + + 14. Size of baculum larger, base more than 3 mm. wide, processes + all well developed.... _Ondatra zibethicus_, p. 198 + + 14´. Size of baculum smaller, base less than 3 mm. wide, processes + poorly developed in some animals.... _Neofiber alleni_, p. 209 + + 15. At least one digital ossification present 16 + + 15´. Digital ossifications not present.... _Dicrostonyx + groenlandicus_, p. 193 + + 16. Breadth of stalk at least 1/2 length of stalk 17 + + 16´. Breadth of stalk less than 1/2 length of stalk 19 + + 17. Length of stalk greater than 3.6 mm. and less than 1-1/2 + times its greatest breadth.... _Microtus richardsoni_, p. 199 + + 17´. Length of stalk usually less than 3.6 mm., or if more than + 3.6 mm. (up to 4.0 mm.) then length 1-1/2 times or more its + greatest breadth 18 + + 18. Median process attenuate distally in dorsal view, and + relatively long (more than twice its own breadth), 1/5 to 3/5 the + length of stalk; breadth of stalk usually 2/3 or more length of + stalk.... _Microtus miurus_, p. 200 + + 18´. Median process relatively blunt distally in dorsal view, + relatively short (usually less than 1/4 length of stalk), breadth + of stalk usually less than 2/3 length of stalk.... + _Pitymys_, p. 208, _Pedomys_, p. 207, or _Microtus mexicanus_, p. 205 + + 19. Distal processes small and firmly ankylosed to distal end of + shaft.... _Phenacomys longicaudus_, p. 197 + + 19´. Distal processes if present not firmly ankylosed to distal + end of shaft 20 + + 20. Dorsal concavity of base as viewed from proximal end usually + deeper than ventral concavity.... _Microtus mexicanus_, p. 205 + + 20´. Dorsal and ventral concavities of base equal in depth or + ventral one the deeper 21 + + 21. Total length of baculum more than 3.6 mm.... _Microtus + californicus_, p. 205 + + 21´. Total length of baculum less than 3.6 mm.... _Synaptomys + cooperi_, p. 194 + + + + +DISCUSSION + + +Owing to shortness of lower incisors and present geographic distribution +of the species, Hinton (1926:35) considered the Tribe Lemmi (lemmings) to +be more primitive than the Tribe Microti (voles). The surviving lemmings +are specialized in many features and therefore are considered as advanced +end-products of an evolutionary radiation of a primitive microtine stock, +of which all earlier stages are extinct. + +Hinton regarded _Dicrostonyx_ as the most primitive of the genera of +lemmings on account of its more complex molar teeth (complexity was +considered to be primitive), and on account of the presence of three +primitive longitudinal rows of tubercles in unworn molars. The other +three genera were arranged in order of increasing specialization as +follows: _Synaptomys_, _Myopus_, _Lemmus_. + +If the baculum tended to retain its primitive character while +specializations in the external anatomy developed, and if the above +arrangement is correct the most primitive bacula would be found in +_Dicrostonyx_ and in _Synaptomys_. The baculum in these two genera in +comparison to that in _Myopus_ (as figured by Ognev, 1948:512) and +_Lemmus_ has a slenderer stalk and smaller digital ossifications or none +at all. The baculum in the genera of lemmings increases in robustness and +the development of processes from _Dicrostonyx_, to _Synaptomys_, to +_Myopus_, to _Lemmus_--the same order outlined above for total of +specialization. The two extremes in this series are near the extremes of +variation in bacula to be found in all microtines. The baculum in +lemmings as a group cannot then be considered more primitive than in +voles as a group, although the voles are usually considered to be more +advanced. The situation in the voles, as we shall see, casts a different +light on the matter. + +The voles, Tribe Microti, were considered by Hinton (1926:40) to be more +advanced than the lemmings because the incisors of the voles are longer +and the root of their last lower molar is lingual to the root of the +incisor. Hinton thought also that the murine ancestors of microtines had +shorter incisors and that the backward extension of the incisors in the +voles is a more ancient feature than the hypsodonty of the molars. A +trend in the molar teeth has been toward greater hypsodonty. The voles in +which the molars are least hypsodont are thus considered primitive. These +include the living genera _Clethrionomys_, _Phenacomys_, _Ondatra_, +_Dolomys_, _Ellobius_, and _Prometheomys_. Therefore, the baculum, in +these assumedly primitive genera, would be expected to resemble the +baculum in the lemmings or at least the most primitive lemmings. This is +not the case. + +The bacula that I have examined of _Clethrionomys_ and _Phenacomys_ have +well-developed digital ossifications. In this they resemble the baculum +of the genus _Lemmus_, the most advanced genus of lemmings according to +Hinton. The baculum of _Dolomys_ has not been studied. The baculum in +_Ondatra_, and in _Prometheomys_ as illustrated by Ognev (1948:552), also +possesses well-developed processes. The baculum of _Ellobius_ is small +and lacks processes (as figured by Ognev, 1950:662). No ossification was +found in a single specimen of _Ellobius_ examined by me although the +entire glans penis was removed and cleared without dissection. So far as +known then, with the exception of _Ellobius_ and _Phenacomys longicaudus_ +(Dearden, 1958:547), the primitive microtines having rooted molars +possess bacula having three well-developed ossified processes. + +Voles of the genus _Microtus_ vary in the structure of the baculum almost +as much as do the lemmings. Within the single subgenus _Microtus_ some +individuals of _Microtus mexicanus_, for example, have minute ossified +lateral processes and other individuals lack these processes; _Microtus +pennsylvanicus_ and some other species have proportionately large lateral +ossifications. If the well-developed condition of the baculum in the +microtines having rooted molars is primitive, then within the genus +_Microtus_ those species having well-developed bacula may be considered +primitive. + +The genera _Lagurus_ and _Neofiber_ have moderately developed or +well-developed lateral processes. _Neofiber_ exhibits a tendency, not +prominent elsewhere, to have a proportionately smaller median process +rather than reduced lateral processes. + +American species of _Microtus_ (genus and subgenus) that have moderately- +to well-developed ossified lateral processes are _M. townsendii_, _M. +oeconomus_, _M. pennsylvanicus_, _M. montanus_, and _M. chrotorrhinus_. +_Microtus_ of other subgenera having this type of baculum include _M. +(Herpetomys) guatemalensis_, _M. (Chilotus) oregoni_, and _M. (Chionomys) +longicaudus_. + +American species of _Microtus_ (genus and subgenus) in which the lateral +ossifications are weakly developed or absent (although cartilaginous +lateral processes are present) include _M. mexicanus_ and _M. +californicus_. In other subgenera, species of _Microtus_ having reduced +lateral ossifications are _M. (Pedomys) ochrogaster_, _M. (Pitymys) +pinetorum_, _M. (Pitymys) parvulus_, _M. (Pitymys) quasiater_, _M. +(Arvicola) richardsoni_, and _M. (Stenocranius) miurus_. + +The microtines are essentially holarctic in distribution. Both of the +tribes, the lemmings and the voles, as well as primitive representatives +of each tribe (not considering _Ellobius_) occur in both the Old World +and New World. It is not certain on which continent (or continents) the +Microtinae first differentiated. It is certain, however, that at various +times, both early and late in the evolution of the subfamily, +representatives have crossed from Eurasia to North America or _vice +versa_. Each of 10 or more microtines in the New World is more closely +related to some microtine in the Old World than to any other microtine in +the New World. + +The similarities or differences in the baculum in Old World and New World +representatives placed in the same genus or subgenus, or thought to be +"companion species" have been commented upon in accounts of _Lemmus_, +_Dicrostonyx_, _Clethrionomys_, _Lagurus_, _Arvicola_, _Stenocranius_, +_Chilotus_, _Chionomys_, _Pitymys_, and in accounts of _Microtus +agrestis_ as compared with _M. pennsylvanicus_, and _Microtus oeconomus_ +(both Old World and New World). + +The baculum in the Microtinae more closely resembles the baculum in the +Cricetinae of the Old World than in the Murinae, or than in any other +rodents known to me. This resemblance suggests relationship between +Microtinae and Cricetinae. + + + + +LITERATURE CITED + + +ARGYROPULO, A. I. + + 1933a. Die Gattungen und Arten der Hamster (_Cricetinae_ Murray, 1866) + der Paläarktik. Zeitschr. f. Säugetierkunde, 8:129-149, 27 figs. in + text. + + 1933b. Über zwei neue paläarktische Wühlmäuse. Zeitschr. f. + Säugetierkunde, 8:180-183, 3 figs. in text. + +CALLERY, R. + + 1951. Development of the os genitale in the golden hamster, + _Mesocricetus (Cricetus) auratus_. Jour. Mamm., 32:204-207, 1 fig. in + text. + +CHAMBERLAIN, J. L. + + 1954. The Block Island meadow mouse, _Microtus provectus_. Jour. Mamm., + 35:587-589, 2 tables in text. + +DEARDEN, L. C. + + 1958. The baculum in _Lagurus_ and related microtines. Jour. Mamm., + 39:541-553, 1 fig. in text. + +DIDIER, R. + + 1943. L'os pénien des Campagnols de France du Genre _Arvicola_. + Mammalia, 7:74-79, 10 figs. in text. + + 1954. Etude systématique de l'os pénien des Mammifères (suite), + Rongeurs: Muridés. Mammalia, 18:237-256, 14 figs. in text. + +ELLERMAN, J. R. + + 1941. The families and genera of living rodents. Vol. II. Family + Muridae. The British Museum (Natural History), London, pp. xii + 690, + 50 figs. + +FRILEY, CHARLES E. + + 1947. Preparation and preservation of the baculum of mammals. Jour. + Mamm., 28:395-397, 1 fig. in text. + +HALL, E. R., and E. L. COCKRUM. + + 1953. A synopsis of the North American microtine rodents. Univ. Kansas + Publ., Mus. Nat. Hist., 5:373-498, 149 figs. in text. + +HAMILTON, W. J., JR. + + 1946. A study of the baculum in some North American Microtinae. Jour. + Mamm., 27:378-387, 3 figs. in text. + +HIBBARD, C. W., and G. C. RINKER. + + 1942. A new bog-lemming (Synaptomys) from Meade County, Kansas. Univ. + Kansas Sci. Bull., 28:25-35, 3 figs. in text. + + 1943. A new meadow mouse (_Microtus ochrogaster taylori_) from Meade + County, Kansas. Univ. Kansas Sci. Bull., 29:255-268, 5 figs. in text. + +HINTON, M. A. C. + + 1926. Monograph of the voles and lemmings (Microtinae), living and + extinct, Vol. I. British Museum (Natural History), London, pp. xvi + + 488, plus 15 plates, 110 figs. in text. + +MATTHEY, R. + + 1953. Les Chromosomes des Muridae. Revue Suisse de Zoologie, + 60:225-283, avec les planches 1 à 4 groupant 84 photomicrographies, 98 + figures et 5 schemas dans le texte. + + 1955. Nouveaux documents sur les chromosomes des Muridae. Problèmes de + cytologie comparée et de taxonomie chez les Microtinae. Revue Suisse de + Zoologie, 62:163-206, avec 114 figures. + +MILLER, G. S. + + 1896. Genera and subgenera of voles and lemmings. North American Fauna + No. 12, pp. 1-85, 40 figs. and 3 plates in text. + +OGNEV, S. I. + + 1948. The mammals of Russia (USSR) and adjacent countries (The mammals + of Eastern Europe and Northern Asia), Vol. 6. Publ. Acad. Sci. USSR, + pp. 1-587, 260 figs., 12 maps, and 11 color plates in text (in + Russian). + + 1950. The mammals of Russia (USSR) and adjacent countries (The mammals + of Eastern Europe and Northern Asia), Vol. 7. Publ. Acad. Sci. USSR, + pp. 1-736, 347 figs., 15 maps, and 10 color plates in text (in + Russian). + +RUTH, E. B. + + 1934. The os priapi: A study in bone development. Anat. Rec., + 60:231-249, 16 figs. in 3 plates. + +SMITH, D. A., and J. B. FOSTER. + + 1957. Notes on the small mammals of Churchill, Manitoba. Jour. Mamm., + 38:98-115, 3 figs. and 3 tables in text. + +WHEELER, B. + + 1956. Comparison of the Block Island "species" of _Microtus_ with _M. + pennsylvanicus_. Evolution, 10:176-186, 4 figs. and 2 tables in text. + +WHITE, J. A. + + 1951. A practical method for mounting the bacula of small mammals. + Jour. Mamm., 32:125. + +ZIMMERMAN, K. + + 1955. Die Gattung _Arvicola_ Lac. im System der Microtinae. + Säugetierkundliche Mitteilungen, 3:110-112, 2 figs. in text. + + _Transmitted August 14, 1959._ + +28-774 + + + + + UNIVERSITY OF KANSAS PUBLICATIONS + MUSEUM OF NATURAL HISTORY + + +Institutional libraries interested in publications exchange may obtain +this series by addressing the Exchange Librarian, University of Kansas +Library, Lawrence, Kansas. Copies for individuals, persons working in a +particular field of study, may be obtained by addressing instead the +Museum of Natural History, University of Kansas, Lawrence, Kansas. There +is no provision for sale of this series by the University Library which +meets institutional requests, or by the Museum of Natural History which +meets the requests of individuals. However, when individuals request +copies from the Museum, 25 cents should be included, for each separate +number that is 100 pages or more in length, for the purpose of defraying +the costs of wrapping and mailing. + +* An asterisk designates those numbers of which the Museum's supply (not +the Library's supply) is exhausted. Numbers published to date, in this +series, are as follows: + + Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950. + + *Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp. + 1-444, 140 figures in text. April 9, 1948. + + Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and + distribution. By Rollin H. Baker. Pp. 1-359, 16 figures in + text. June 12, 1951. + + *2. A quantitative study of the nocturnal migration of birds. + By George H. Lowery, Jr. Pp. 361-472, 47 figures in text. June + 29, 1951. + + 3. Phylogeny of the waxwings and allied birds. By M. Dale + Arvey. Pp. 473-530, 49 figures in text, 13 tables. October 10, + 1951. + + 4. Birds from the state of Veracruz, Mexico. By George H. + Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7 figures in + text, 2 tables. October 10, 1951. + +Index. Pp. 651-681. + + *Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466, 41 + plates, 31 figures in text. December 27, 1951. + + Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953. + + *Vol. 6. (Complete) Mammals of Utah, _taxonomy_ and _distribution_. By + Stephen D. Durrant. Pp. 1-549, 91 figures in text, 30 tables. + August 10, 1952. + + Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73 + figures in text, 37 tables. August 25, 1952. + + 2. Ecology of the opossum on a natural area in northeastern + Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp. 305-338, + 5 figures in text. August 24, 1953. + + 3. The silky pocket mice (Perognathus flavus) of Mexico. By + Rollin H. Baker. Pp. 339-347, 1 figure in text. February 15, + 1954. + + 4. North American jumping mice (Genus Zapus). By Phillip H. + Krutzsch. Pp. 349-472, 47 figures in text, 4 tables. April 21, + 1954. + + 5. Mammals from Southeastern Alaska. By Rollin H. Baker and + James S. Findley. Pp. 473-477. April 21, 1954. + + 6. Distribution of Some Nebraskan Mammals. By J. Knox Jones, + Jr. Pp. 479-487. April 21, 1954. + + 7. Subspeciation in the montane meadow mouse, Microtus + montanus, in Wyoming and Colorado. By Sydney Anderson. Pp. + 489-506, 2 figures in text. July 23, 1954. + + 8. A new subspecies of bat (Myotis velifer) from southeastern + California and Arizona. By Terry A. Vaughan. Pp. 507-512. July + 23, 1954. + + 9. Mammals of the San Gabriel mountains of California. By + Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12 tables. + November 15, 1954. + + 10. A new bat (Genus Pipistrellus) from northeastern Mexico. + By Rollin H. Baker. Pp. 583-586. November 15, 1954. + + 11. A new subspecies of pocket mouse from Kansas. By E. + Raymond Hall. Pp. 587-590. November 15, 1954. + + 12. Geographic variation in the pocket gopher, Cratogeomys + castanops, in Coahuila, Mexico. By Robert J. Russell and + Rollin H. Baker. Pp. 591-608. March 15, 1955. + + 13. A new cottontail (Sylvilagus floridanus) from + northeastern Mexico. By Rollin H. Baker. Pp. 609-612. April 8, + 1955. + + 14. Taxonomy and distribution of some American shrews. By + James S. Findley. Pp. 613-618. June 10, 1955. + + 15. The pigmy woodrat, Neotoma goldmani, its distribution and + systematic position. By Dennis G. Rainey and Rollin H. Baker. + Pp. 619-624, 2 figures in text. June 10, 1955. + +Index. Pp. 625-651. + + Vol. 8. 1. Life history and ecology of the five-lined skink, Eumeces + fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in text. + September 1, 1954. + + 2. Myology and serology of the Avian Family Fringillidae, a + taxonomic study. By William B. Stallcup. Pp. 157-211, 23 + figures in text, 4 tables. November 15, 1954. + + 3. An ecological study of the collared lizard (Crotaphytus + collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in text. + February 10, 1956. + + 4. A field study of the Kansas ant-eating frog, Gastrophryne + olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in text. + February 10, 1956. + + 5. Check-list of the birds of Kansas. By Harrison B. Tordoff. + Pp. 307-359, 1 figure in text. March 10, 1956. + + 6. A population study of the prairie vole (Microtus + ochrogaster) in northeastern Kansas. By Edwin P. Martin. Pp. + 361-416, 19 figures in text. April 2, 1956. + + 7. Temperature responses in free-living amphibians and + reptiles of northeastern Kansas. By Henry S. Fitch. Pp. + 417-476, 10 figures in text, 6 tables. June 1, 1956. + + 8. Food of the crow, Corvus brachyrhynchos Brehm, in + south-central Kansas. By Dwight Platt. Pp. 477-498, 4 tables. + June 8, 1956. + + 9. Ecological observations on the woodrat Neotoma floridana. + By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3 figures + in text. June 12, 1956. + + 10. Eastern woodrat, Neotoma floridana; Life history and + ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13 + figures in text. August 15, 1956. + +Index. Pp. 647-675. + + Vol. 9. 1. Speciation of the wandering shrew. By James S. Findley. Pp. + 1-68, 18 figures in text. December 10, 1955. + + 2. Additional records and extension of ranges of mammals from + Utah. By Stephen D. Durrant, M. Raymond Lee, and Richard M. + Hansen. Pp. 69-80. December 10, 1955. + + 3. A new long-eared myotis (Myotis evotis) from northeastern + Mexico. By Rollin H. Baker and Howard J. Stains. Pp. 81-84. + December 10, 1955. + + 4. Subspeciation in the meadow mouse, Microtus + pennsylvanicus, in Wyoming. By Sydney Anderson. Pp. 85-104, 2 + figures in text. May 10, 1956. + + 5. The condylarth genus Ellipsodon. By Robert W. Wilson. Pp. + 105-116, 6 figures in text. May 19, 1956. + + 6. Additional remains of the multituberculate genus + Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures in + text. May 19, 1956. + + 7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp. + 125-335, 75 figures in text. June 15, 1956. + + 8. Comments on the taxonomic status of Apodemus peninsulae, + with description of a new subspecies from North China. By J. + Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1 table. August + 15, 1956. + + 9. Extensions of known ranges of Mexican bats. By Sydney + Anderson. Pp. 347-351. August 15, 1956. + + 10. A new bat (Genus Leptonycteris) from Coahuila. By Howard + J. Stains. Pp. 353-356. January 21, 1957. + + 11. A new species of pocket gopher (Genus Pappogeomys) from + Jalisco, Mexico. By Robert J. Russell. Pp. 357-361. January + 21, 1957. + + 12. Geographic variation in the pocket gopher, Thomomys + bottae, in Colorado. By Phillip M. Youngman. Pp. 363-387, 7 + figures in text. February 21, 1958. + + 13. New bog lemming (genus Synaptomys) from Nebraska. By J. + Knox Jones, Jr. Pp. 385-388. May 12, 1958. + + 14. Pleistocene bats from San Josecito Cave, Nuevo León, + México. By J. Knox Jones, Jr. Pp. 389-396. December 19, 1958. + + 15. New subspecies of the rodent Baiomys from Central + America. By Robert L. Packard. Pp. 397-404. December 19, 1958. + + 16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson. + Pp. 405-414, 1 figure in text, May 20, 1959. + + 17. Distribution, variation, and relationships of the montane + vole, Microtus montanus. By Sydney Anderson. Pp. 415-511, 12 + figures in text, 2 tables. August 1, 1959. + + 18. Conspecificity of two pocket mice, Perognathus goldmani + and P. artus. By E. Raymond Hall and Marilyn Bailey Ogilvie. + Pp. 513-518, 1 map in text. January 14, 1960. + + 19. Records of harvest mice, Reithrodontomys, from Central + America, with description of a new subspecies from Nicaragua. + By Sydney Anderson and J. Knox Jones, Jr. Pp. 519-529. January + 14, 1960. + + 20. Small carnivores from San Josecito Cave (Pleistocene), + Nuevo León, México. By E. Raymond Hall. Pp. 531-538, 1 figure + in text. January 14, 1960. + + 21. Pleistocene pocket gophers from San Josecito Cave, Nuevo + León, México. By Robert J. Russell. Pp. 539-548, 1 figure in + text, January 14, 1960. More numbers will appear in volume 9. + + Vol. 10. 1. Studies of birds killed in nocturnal migration. By Harrison + B. Tordoff and Robert M. Mengel. Pp. 1-44, 6 figures in text, + 2 tables. September 12, 1956. + + 2. Comparative breeding behavior of Ammospiza caudacuta and + A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates, 1 + figure. December 20, 1956. + + 3. The forest habitat of the University of Kansas Natural + History Reservation. By Henry S. Fitch and Ronald R. McGregor. + Pp. 77-127, 2 plates, 7 figures in text, 4 tables. December + 31, 1956. + + 4. Aspects of reproduction and development in the prairie + vole (Microtus ochrogaster). By Henry S. Fitch. Pp. 129-161, 8 + figures in text, 4 tables. December 19, 1957. + + 5. Birds found on the Arctic slope of northern Alaska. By + James W. Bee. Pp. 163-211, plates 9-10, 1 figure in text. + March 12, 1958. + + 6. The wood rats of Colorado: distribution and ecology. By + Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures in + text, 35 tables. November 7, 1958. + + 7. Home ranges and movements of the eastern cottontail in + Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3 figures + in text. May 4, 1959. + + 8. Natural history of the salamander Aneides hardyi. By + Richard F. Johnston and Gerhard A. Schad. Pp. 573-585. October + 8, 1959. + +More numbers will appear in volume 10. + + Vol. 11. 1. The systematic status of the colubrid snake, Leptodeira + discolor Günther. By William E. Duellman. Pp. 1-9, 4 figures. + July 14, 1958. + + 2. Natural history of the six-lined racerunner, Cnemidophorus + sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figures, 9 + tables. September 19, 1958. + + 3. Home ranges, territories, and seasonal movements of + vertebrates of the Natural History Reservation. By Henry S. + Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3 tables. + December 12, 1958. + + 4. A new snake of the genus Geophis from Chihuahua, Mexico. + By John M. Legler. Pp. 327-334, 2 figures in text. January 28, + 1959. + + 5. A new tortoise, genus Gopherus, from north-central Mexico. + By John M. Legler. Pp. 335-343. April 24, 1959. + + 6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By + Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in text, 10 + tables. May 6, 1959. + + 7. Fishes of the Big Blue River Basin, Kansas. By W. L. + Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5 tables. + May 8, 1959. + + 8. Birds from Coahuila, México. By Emil K. Urban. Pp. + 443-516. August 1, 1959. + + 9. Description of a new softshell turtle from the + southeastern United States. By Robert G. Webb. Pp. 517-525, 2 + plates, 1 figure in text. August 14, 1959. + +Another number will appear in volume 11. + + Vol. 12. 1. Functional morphology of three bats: Eumops, Myotis, + Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24 figures + in text. July 8, 1959. + + 2. The ancestry of modern Amphibia: a review of the evidence. + By Theodore H. Eaton, Jr. Pp. 155-180, 10 figures in text. + July 10, 1959. + + 3. The baculum in microtine rodents. By Sydney Anderson. Pp. + 181-216, 49 figures in text. February 19, 1960. + +More numbers will appear in volume 12. + + + + + + +End of the Project Gutenberg EBook of The Baculum in Microtine Rodents, by +Sydney Anderson + +*** END OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + +***** This file should be named 38021-8.txt or 38021-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/8/0/2/38021/ + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/38021-8.zip b/38021-8.zip Binary files differnew file mode 100644 index 0000000..cc8853c --- /dev/null +++ b/38021-8.zip diff --git a/38021-h.zip b/38021-h.zip Binary files differnew file mode 100644 index 0000000..5f8825a --- /dev/null +++ b/38021-h.zip diff --git a/38021-h/38021-h.htm b/38021-h/38021-h.htm new file mode 100644 index 0000000..060986e --- /dev/null +++ b/38021-h/38021-h.htm @@ -0,0 +1,3279 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> + +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> + <head> + <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1" /> + <meta http-equiv="Content-Style-Type" content="text/css" /> + <title> + The Project Gutenberg eBook of The Baculum in Microtine Rodents by Sydney Anderson. + </title> + <style type="text/css"> + +/*Text and Body*/ + +body { + margin-left: 10%; + margin-right: 10%; + font-size: 100%; +} + +h1 { + font-size: 4em; + text-align: center; + clear: both; +} + +h2,h3,h4,h5,h6 { + text-align: center; + clear: both; + margin-top: 2.5em; + margin-bottom: 1em; +} + +p { + margin-top: .75em; + text-align: justify; + margin-bottom: .75em; +} + +.title { + font-size:115%; + text-align:center; +} + +.right { + text-align: right; + margin-right: 1em; +} + + +hr { + width: 100%; + margin-top: 2em; + margin-bottom: 2em; + margin-right: auto; + margin-left: auto; +} + +table { + margin:0px auto; +} + +td.left { + text-align: left; +} + +td.bump1 { + padding-left:1.5em; +} + +td.bump2 { + padding-left:3em; +} + +td.bump3 { + padding-left:5em; +} + +td.bump4 { + padding-left:6em; +} + +td.center { + text-align:center; +} + +th { + text-align:center; +} + +.pagenum { + position: absolute; + left: 92%; + font-size: smaller; + text-align: right; +} + +.center { + text-align: center; +} + +.smcap { + font-variant: small-caps; +} + + +/* Image Styles*/ + +.imgcenter { + margin: auto; + text-align: center; +} + +.caption { + font-weight: bold; +} + + +/* Specialized Ordered Lists */ + +OL#start_02 { counter-reset: item 1 } +OL#start_14 { counter-reset: item 13 } +OL#start_26 { counter-reset: item 25 } +OL#start_40 { counter-reset: item 39 } +OL.start_1 {counter-reset: item 0;} +LI { display: block } +LI:before { + content: counter(item) ". "; + counter-increment: item; +} + +dd.small_margin { + margin-left:0px; +} + + +/* Fraction Fixes */ +sup, +sub { + height: 0; + line-height: 1; + vertical-align: baseline; + vertical-align: bottom; + position: relative; + +} + +sup { + bottom: 1ex; +} + +sub { + top: .5ex; +} + +table.key { + margin:0px auto; +} + +td.text { + width:700px; + padding-right:10px; +} + +td.text_left { + width:700px; + padding-left:20px; + text-align:justify; +} + +td.number { + width:100px; +} + +td.litcit_num { + width:50px; + text-align:right; + vertical-align:top; + padding-left:15px; +} + +td.num_up { + width:100px; + vertical-align:top; + text-align:right; +} + +td.litcit_txt { + width:750px; + padding-left:10px; +} + + + </style> +</head> + + +<body> + + +<pre> + +Project Gutenberg's The Baculum in Microtine Rodents, by Sydney Anderson + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Baculum in Microtine Rodents + +Author: Sydney Anderson + +Release Date: November 15, 2011 [EBook #38021] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + + + + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + + + + + +</pre> + + +<p class="smcap center">University of Kansas Publications<br /> +Museum of Natural History</p> + +<p class="center">Volume 12, No. 3, pp. 181-216, 49 figs.<br /> +February 19, 1960</p> + +<h1>The Baculum in Microtine Rodents</h1> + +<p class="center" style="font-size:larger;">BY<br /> +SYDNEY ANDERSON</p> + +<p class="smcap center" style="margin-top:3em;">University of Kansas<br /> +Lawrence<br /> +1960</p> + +<p class="smcap center" style="margin-top:3em;">University of Kansas Publications, Museum of Natural History</p> + +<p class="center">Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson</p> + +<p class="center">Volume 12, No. 3, pp. 181-216, 49 figs.<br /> +Published February 19, 1960</p> + +<p class="center"><span class="smcap">University of Kansas</span><br /> +Lawrence, Kansas</p> + +<p class="center" style="font-size:smaller;">PRINTED IN<br /> +THE STATE PRINTING PLANT<br /> +TOPEKA, KANSAS<br /> +1960</p> + +<div class="imgcenter" style="width: 100px;"> +<img src="images/001.jpg" width="100" height="39" alt="" title="" /> +</div> + +<p class="center">28-774</p> + + +<hr /> + +<p><span class="pagenum"><a name="Page_183" id="Page_183">[Pg 183]</a></span></p> + +<p class="center" style="font-size:2em;">The Baculum in Microtine Rodents</p> +<p class="center">BY<br />SYDNEY ANDERSON</p> + +<h2>INTRODUCTION</h2> + +<p>Didier (1943, 1954) has described the bacula of several Old World +microtines, and other rodents. Argyropulo studied (1933a, 1933b) five +species of Cricetinae and <i>Microtus socialis</i>. Ognev (1950) +illustrated numerous species of Eurasian microtines. Hamilton (1946) +figured and described the baculum of 11 species of North American +microtines. Hibbard and Rinker (1942, 1943) figured the baculum of +<i>Synaptomys cooperi paludis</i> and of <i>Microtus ochrogaster +taylori</i>. Dearden (1958) studied the baculum in two Asiatic species of +<i>Lagurus</i>, in six subspecies of <i>Lagurus curtatus</i> of North +America, and in six other species of microtines of other genera.</p> + +<p>The baculum can be preserved easily with standard study skins, and is +potentially useful in interpreting relationships on any taxonomic level, +and especially in determining the relationships of species within a +genus, if used together with other structures.</p> + +<p>The anatomical orientation of the baculum needs comment because some +confusion exists in the literature, especially concerning the use of the +terms ventral and dorsal. The urethra lies on the anatomically ventral +side of the penis, and of the baculum. In the center of the penis lies a +single corpus cavernosum penis, shown in cross section proximal to the +baculum in Figure 1c. Dorsally an artery, thinner walled than the ventral +urethra, ends in a somewhat reticulate sinus surrounding primarily the +middle part of the baculum within the bulbous glans penis. The corpus +cavernosum penis (the structure has no median septum, at least distally) +terminates with the baculum and is closely knit to it. The site of this +bond is evident in the tuberosities and sculpturing of the base of the +baculum.</p> + +<p>The part of the penis enclosing the baculum, when not erect, is folded +back as shown in Figures 1a and 1b. As a result the anatomically ventral +surface faces upwards, or at least posterodorsally. The use of the term +ventral in this account refers to the anatomically ventral side, that is +to say to the side of the baculum facing the urethra.</p> + +<p>The baculum in microtines consists of an elongate stalk, having a +laterally, and to a lesser extent dorsoventrally, expanded base and + +<span class="pagenum"><a name="Page_184" id="Page_184">[Pg +184]</a></span> + +an attenuate distal shaft. Usually, three digitate processes of +cartilaginous material in which additional ossifications may occur arise +from the terminus of the shaft. The proportions and curvature of the +stalk vary as do the proportions of the terminal ossifications to each +other and to the stalk. In some species one or more of the digital +processes are frequently completely unossified.</p> + +<div class="imgcenter" style="width: 500px;"> +<img src="images/184a.jpg" width="500" height="203" alt="Diagram a, b, c." title="" /> +</div> + +<div class="imgcenter" style="width: 500px;"> +<img src="images/184b.jpg" width="500" height="268" alt="Graph. X-axis: Length of Animal in Millimeters. Y-axis: Length of Stalk of Baculum in Millimeters." title="" /> +</div> + +<p><span class="smcap">Figure 1.</span> The +baculum in <i>Microtus ochrogaster</i>—orientation and variation +with age. <i>a.</i> Diagram of a sagittal section of the posterior half +of a vole, natural size. The penis, containing the baculum (in black), +extends ventrally from a point posterior to the pubic symphysis +(stippled), along the body wall, and bends posteriorly at the distal end. +<i>b.</i> Distal end of penis (× 2) showing baculum (in black), the +urethra (solid lines) adjacent to the baculum, and the corpus cavernosum +(broken lines) proximal to the baculum. <i>c.</i> Oblique view of the +cross section of penis (× 4) shown in Figure 1 <i>b</i>. The +thick-walled urethra lies ventral to the curved corpus cavernosum. A +thinner-walled blood-vessel lies dorsal to the corpus cavernosum. The +anatomically ventral side of the baculum, in the normal non-erect penis +shown, is seen to face dorsally. <i>d.</i> Graph showing the relationship +between size of baculum, size of animal, and development of digital +ossifications. Circles show presence of ossification in stalk only; +circles enclosing dots indicate presence of secondary ossification in +median process also; large dots indicate the addition of tertiary +ossification in one or both of the lateral digitate processes.</p> + +<p><span class="pagenum"><a name="Page_185" id="Page_185">[Pg +185]</a></span></p> + +<p>Preserved specimens of <i>Microtus arvalis</i>, <i>Microtus +agrestis</i>, <i>Microtus orcadensis</i>, <i>Microtus nivalis</i>, +<i>Microtus guentheri</i>, <i>Microtus subterraneus</i>, <i>Clethrionomys +glareolus</i>, and <i>Ellobius lutescens</i> were provided by Prof. +Robert Matthey of Lausanne, Switzerland. J. Knox Jones, Jr. carefully +saved the bacula with specimens of <i>Microtus fortis</i> and +<i>Clethrionomys rufocanus</i> from Korea. Dr. W. B. Quay, Department of +Zoology, University of California, supplied specimens of <i>Synaptomys +cooperi</i>, <i>Phenacomys intermedius</i>, and <i>Microtus oregoni</i>. +Dr. Franklin Sturges and Mr. John W. Goertz, Museum of Natural History, +Oregon State College, Corvallis, have provided specimens including bacula +of <i>Clethrionomys occidentalis</i>, <i>Microtus oregoni</i>, and +<i>Microtus townsendii</i>. Dr. Randolph L. Peterson and Mr. Bristol +Foster, Royal Ontario Museum of Zoology, Toronto, Canada, provided +specimens of <i>Phenacomys intermedius</i>. Dr. J. N. Layne, University +of Florida, Gainsville, Florida, presented me with a baculum of +<i>Microtus parvulus</i>.</p> + +<p>I am indebted to all of these persons for their aid, and to various +collectors for the Museum of Natural History, who preserved bacula with +specimens. Many of these specimens were obtained through the assistance +of the University of Kansas Endowment Association and the National +Science Foundation.</p> + + +<h2>METHODS</h2> + +<p>Bacula were obtained from fresh specimens, specimens preserved in +alcohol or formalin, and dried study skins. The processing of bacula has +been discussed by Hamilton (1946), Friley (1947), White (1951), and +Dearden (1958). The methods used to preserve bacula for my study differed +some from any of those reported. The terminal part of each penis +including the baculum imbedded in the glans penis was removed in its +entirety and placed in a vial. The catalogue number was kept with each +specimen at all times. A two per cent solution of potassium hydroxide was +added. All specimens were examined at least once a day. If tissues other +than the glans penis were present they were removed with forceps when +softened usually at the end of one day. Several drops of Alizarin red-S +stain in a saturated alcoholic solution were added to the 3 to 5 ccs. of +KOH solution in each vial. Solutions were replaced if they became turbid +enough to obstruct observation of the clearing penis. After one day the +solution containing stain was removed and replaced with two per cent KOH +solution without stain. When the glans became sufficiently cleared that +the stained baculum could be seen easily, the solution was replaced by +glycerin in which clearing was completed. The time required for the +entire process varied from one day to more than two weeks depending on +the size of the specimen and on its condition. Fresh specimens clear more +rapidly than dried specimens, and those that are dried more rapidly than +those that are preserved. A three or four per cent solution of hydroxide +will hasten the process, but more frequent observation is required to +prevent excessive maceration.</p> + +<p>Specimens were then examined in a shallow dish containing glycerin +under a binocular microscope. The baculum can be viewed from any desired +direction. The method described above leaves the baculum intact within +the glans penis; therefore its orientation can be determined relative to +the thick walled urethra and the thin walled dorsal artery that extends +onto the dorsal side of the baculum. The ventral curvature of the penis +proximal to the baculum, and the distal extension, characteristic of most +species, of the dorsal border of + +<span class="pagenum"><a name="Page_186" id="Page_186">[Pg +186]</a></span> + +the glans (both shown in Figure 1) are other features aiding in correctly +orienting cleared specimens. The digitate processes are not so often +injured, lost, or displaced when the method described above is used as +they are when the penis is dissected. Specimens were stored in glycerin +in glass shell vials having polyethylene stoppers. A small card bearing +the name, number, locality, and other data was placed in each vial. A +specimen thus enclosed can be kept indefinitely, or removed and mounted +in balsam as described by White (1951:631) or in plastic as described by +Dearden (1958:541) and thus stored in the vial containing the skull of +the specimen.</p> + +<p>Drawings were made on millimeter ruled paper while the baculum was +viewed under a binocular microscope with a square ruled eyepiece.</p> + +<p>Unless otherwise noted all specimens listed are in the University of +Kansas Museum of Natural History. Catalogue numbers are cited. +Measurements are accurate to within less than one-tenth of a millimeter. +Proportions as stated in the text are approximations, accurate to within +one-twelfth (8.33 per cent). The range of variation is unknown for some +species. Mention is made if maturity is known or suspected to differ in +specimens being compared.</p> + +<p>The development of the baculum has been studied by Callery (1951) in +<i>Mesocricetus auratus</i> and by Ruth (1934) in the laboratory rat. In +the rat (<i>Rattus norvegicus</i>) the bone is of endoblastemal origin +being laid down by a condensation of undifferentiated mesenchymal cells. +At the distal end of the bone dense fibrous tissue is then differentiated +and at the proximal end hyaline cartilage. Growth is by substitution at +the proximal end and by subperiosteal lamellation circumferentially. A +marrow cavity is formed by resorption. In the baculum of the hamster the +primary center of ossification is in the stalk, and is present at the age +of three days; the secondary centers are in lateral processes and are +present at 80 days and enlarge subsequently. A tertiary center, in each +median process, may or may not develop later. Maximum development of the +baculum is reached late in the reproductive life of the hamster.</p> + +<p>The early ossification of the baculum noted in the rat and the hamster +occurs in <i>Microtus</i> also. A specimen of <i>Microtus montanus +fusus</i> (76831, from 5 mi. N, 26 mi. W Saguache, 9600 ft., Saguache +County, Colorado) only 74 mm. in total length and weighing only 6.6 +grams, had a slender ossified baculum having enlarged ends. This vole was +one-half of the average length and less than one-fifth of the average +weight of an adult, and of approximately the size at which weaning takes +place.</p> + +<p>The development of the baculum in <i>Microtus ochrogaster</i> was +studied in 32 specimens of various ages. The specimens (between Nos. +74994 and 75074) were collected between August 15 and September 4, 1957, +at localities on the Great Plains. These specimens were from breeding +populations, as evidenced by pregnancy of females and by large size of +testes of males. The length and width of the stalk of the baculum, the +presence of digital ossifications, the + +<span class="pagenum"><a name="Page_187" id="Page_187">[Pg +187]</a></span> + +total length of the animal, and the size of the testes were noted. +Variability in length of testes is greatest when voles are from 140 to +150 mm. in total length. Sexual maturity is reached rather abruptly when +the total length of most individuals is 140 to 150 millimeters. If the +baculum likewise underwent more rapid growth at the onset of sexual +maturity, greater variability should be evident in the length of the +baculum of voles 140 to 150 mm. in total length than in bacula of voles +of other sizes. This was the case (see Figure 1d). The baculum does not, +however, suddenly reach its maximum maturity.</p> + +<p>The primary ossification is in the stalk. The secondary ossification +is in the median process except in <i>Lagurus</i> (Dearden, 1958:551) and +some individuals of <i>Neofiber</i> (see account on page 258). Tertiary +centers of ossification are in the lateral processes. The primary +ossification is present at an early age and subsequently increases in +size and solidity. The secondary and tertiary ossifications are +progressively more common in older voles. The increase in degree of +ossification of all parts continues after sexual maturity is reached. +Individual variation and variation with age in the baculum of <i>Microtus +pennsylvanicus</i> have been illustrated by Hamilton (1946:380). Figures +14, 15, and 17 illustrate variation with size, which is correlated with +age, and also illustrate individual variation. The three bacula are from +adult voles having testes that measured 15, 16 and 16 mm. in length, +respectively. Each vole was trapped in late June. The total lengths in +millimeters of the three voles are 172, 167, and 181; weights are 55, +52.4, and 65.5 grams. I judge that the greater size of the stalk and the +better developed base shown in Figure 17 than in Figure 15 are +illustrative of age variation; the difference in the size of the lateral +digitate processes is, in this case, attributable to individual +variation. Differences in the distal end of the baculum in Figures 42 and +43, show individual variation also. Figures 35 and 36 represent two +different subspecies; different individuals of <i>M. mexicanus +mogollonensis</i>, however, exhibit individual variation of the same +degree.</p> + +<p>Hall and Cockrum (1953) list 44 species of microtines in North +America. At least twelve of these are insular or local forms perhaps +derived from some other species; for example <i>Microtus coronarius</i>, +an insular form derived from <i>Microtus longicaudus</i>; <i>Microtus +provectus</i>, considered by Chamberlain (1954:587) and by Wheeler +(1956:176) as a subspecies of <i>Microtus pennsylvanicus</i>; and +<i>Microtus ludovicianus</i>, a close relative of <i>Microtus +ochrogaster</i>.</p> + +<p>All North American genera have been studied. Of the genus +<i>Microtus</i> in North America, all subgenera but <i>Orthriomys</i> and +all species but the following nine, have been studied: <i>M. (Orthriomys) +umbrosus</i>, the insular <i>M. (Stenocranius) abbreviatus</i>, <i>M. +(Microtus) breweri</i>, <i>M. (Microtus) nesophilus</i>, <i>M.</i></p> + +<p><span class="pagenum"><a name="Page_188" id="Page_188">[Pg +188]</a></span></p> + +<div class="imgcenter" style="width: 421px;"> +<img src="images/188.jpg" width="421" height="500" alt="" title="" /> +</div> + +<p><span class="smcap">Figures</span> 2-13. Bacula of microtines. Unless +indicated otherwise views are (<i>a</i>) of the dorsum, (<i>b</i>) the +right side, and (<i>c</i>) the proximal end with the dorsal surface +upward. Exact localities are given in accounts of species concerned.</p> + +<ol id="start_02"> + <li><i>Lemmus trimucronatus</i>, 50678, Point Barrow, Alaska.</li> + <li><i>Dicrostonyx groenlandicus</i>, 50539, Porcupine Lake, Brooks Range, + Alaska.</li> + <li><i>Dicrostonyx groenlandicus</i>, 52524, Point Barrow, Alaska.</li> + <li><i>Synaptomys cooperi saturatus</i>, WBQ 3-C-454, 3 mi. S Demotte, Indiana.</li> + <li><i>Synaptomys cooperi paludis</i>, 13716, Meade County State Park, Kansas.</li> + <li><i>Phenacomys intermedius celatus</i>, SA 2044, Quebec.</li> + <li><i>Phenacomys intermedius intermedius</i>, WBQ 3-C-309, 5.4 mi. S Moran, + Teton Co., Wyoming.</li> + <li><i>Clethrionomys rufocanus</i>, 60438, 1 mi. NW Oho-ri, Korea, (<i>d</i>) ventral + view.</li> + <li><i>Clethrionomys gapperi</i>, 42108, 31 mi. N Pinedale, Wyoming.</li> + <li><i>Clethrionomys rutilus</i>, 42865, 5 mi. NNE Gulkana, Alaska.</li> + <li><i>Clethrionomys occidentalis</i>, FWS 30, Mary's Peak, Benton Co., Oregon.</li> + <li><i>Clethrionomys glareolus</i>, 67100, Zermatt, Valais, Switzerland.</li> +</ol> + +<p><span class="pagenum"><a name="Page_189" id="Page_189">[Pg +189]</a></span></p> + +<div class="imgcenter" style="width: 431px;"> +<img src="images/189.jpg" width="431" height="500" alt="" title="" /> +</div> + +<p><span class="smcap">Figures</span> 14-25. Bacula of <i>Microtus</i>. +Unless indicated otherwise views are (<i>a</i>) of the dorsum, (<i>b</i>) +the right side, and (<i>c</i>) the proximal end with dorsal surface +upward.</p> + +<ol id="start_14"> + <li><i>M. pennsylvanicus</i>, 42439, 1 mi. S, 2 mi. E Eagle Nest, Colfax +Co., New Mexico; abnormality perhaps owing to injury; dorsal view.</li> + <li><i>M. pennsylvanicus</i>, 42306, 5 mi. N, 26 mi. W Saguache, Colorado; + dorsal view.</li> + <li><i>M. pennsylvanicus</i>, 43043, 20 mi. NE Anchorage, Alaska, ventral view.</li> + <li><i>M. pennsylvanicus</i>, 42430, 1 mi. S, 2 mi. E Eagle Nest, New Mexico.</li> + <li><i>M. agrestis</i>, 67102, Gryon, Switzerland.</li> + <li><i>M. montanus amosus</i>, 62241, 1/2 mi. E Soldier Summit, Wasatch Co., + Utah.</li> + <li><i>M. montanus nanus</i>, 57470, 2 mi. N, 2 mi. W Pocatello, Idaho.</li> + <li><i>M. montanus fusus</i>, 42307, 5 mi. N, 26 mi. W Saguache, Colorado.</li> + <li><i>M. arvalis</i>, 67101, Vidy, Switzerland, possibly not mature.</li> + <li><i>M. guentheri</i>, 67104, Palestine.</li> + <li><i>M. orcadensis</i>, 67106, Orkney Islands, orientation uncertain.</li> + <li><i>M. fortis</i>, 63841, Chipo-ri, Korea, (<i>d</i>) ventral view.</li> +</ol> + +<p><span class="pagenum"><a name="Page_190" id="Page_190">[Pg +190]</a></span></p> + +<div class="imgcenter" style="width: 432px;"> +<img src="images/190.jpg" width="432" height="500" alt="" title="" /> +</div> + +<p><span class="smcap">Figures</span> 26-39. Bacula of microtines. Unless indicated +otherwise views are (<i>a</i>) of the dorsum, (<i>b</i>) the right side, +and (<i>c</i>) the proximal end with the dorsal surface upward.</p> + +<ol id="start_25"> + <li><i>M. (Pitymys) fatioi</i>, 67103, Zermatt, Switzerland, immature.</li> + <li><i>M. (Pitymys) pinetorum</i>, 76834, 2 mi. N Baldwin, Douglas Co., Kansas.</li> + <li><i>M. (Pitymys) pinetorum</i>, 68545, 1 mi. NE Pleasant Grove, Kansas.</li> + <li><i>M. (Pitymys) quasiator</i>, 30709, Teocelo, Veracruz, (<i>d</i>) ventral view.</li> + <li><i>M. (Pitymys) quasiator</i>, 19878, 5 km. N Jalapa, Veracruz.</li> + <li><i>M. (Pedomys) ochrogaster</i>, 75036, 1 mi. N, 2 mi. E Oberlin, Kansas.</li> + <li><i>M. (Stenocranius) miurus</i>, 51152, Lake Schrader, Brooks Range, Alaska.</li> + <li><i>M. (Stenocranius) miurus</i>, 51169, Lake Schrader, Brooks Range, Alaska.</li> + <li><i>M. (Stenocranius) gregalis</i>, 8059, "Eastern Europe."</li> + <li><i>M. mexicanus mexicanus</i>, 63094, Valle de Bravo, Estado de México, México.</li> + <li><i>M. mexicanus mogollonensis</i>, 63298, Mt. Taylor, Valencia Co., New Mexico.</li> + <li><i>M. californicus</i>, 76828, 1 mi. NE Berkeley, California; (<i>d</i>) ventral view.</li> + <li><i>M. (Arvicola) richardsoni</i>, 42454, 31 mi. N Pinedale, Sublette Co., Wyoming.</li> + <li><i>M. richardsoni</i>, 37903, 23-1/2 mi. S, 5 mi. W Lander, Wyoming; distal end.</li> +</ol> + +<p><span class="pagenum"><a name="Page_191" id="Page_191">[Pg +191]</a></span></p> + +<div class="imgcenter" style="width: 420px;"> +<img src="images/191.jpg" width="420" height="500" alt="" title="" /> +</div> + +<p><span class="smcap">Figures</span> 40-49. Bacula of microtines. Unless +indicated otherwise views are (<i>a</i>) of the dorsum, (<i>b</i>) the +right side, and (<i>c</i>) the proximal end with the dorsal surface +upward.</p> + +<ol id="start_39"> + <li><i>Microtus (Pitymys) parvulus</i>, UF 1508, 1 mi. W Micanopy, Florida.</li> + <li><i>Microtus townsendii</i>, 79186, Sec. 33, T. 11S, R. 5W, Benton Co., Oregon.</li> + <li><i>Microtus (Herpetomys) guatemalensis</i>, 65895, 2 mi. S San Juan Ixcoy, Guatemala.</li> + <li><i>M. guatemalensis</i>, 65921, 10 mi. E, 4 mi. S Totonicapan, Guatemala, dorsal view + of tip.</li> + <li><i>Microtus oeconomus</i>, 43048, Kelsall Lake, British Columbia.</li> + <li><i>Microtus (Chilotus) oregoni</i>, WBQ 3-C-248, 5 mi. N Orick, California.</li> + <li><i>Lagurus (Lemmiscus) curtatus</i>, 26053, 9 mi. S Robertson, Uinta Co., Wyoming.</li> + <li><i>Microtus (Chionomys) nivalis</i>, 65127, Wetterstein, Germany, orientation uncertain.</li> + <li><i>Microtus (Chionomys) longicaudus</i>, 50253, Crane Flat, Mariposa Co., California.</li> + <li><i>Neofiber alleni</i>, 27268, 2 mi. S Gainesville, Florida, orientation uncertain.</li> +</ol> + +<p><span class="pagenum"><a name="Page_192" id="Page_192">[Pg +192]</a></span></p> + +<p style="margin-bottom:2em;"><i>(Microtus) provectus</i> (the last three are probably insular +derivatives of <i>M. pennsylvanicus</i>), <i>M. (Microtus) +fulviventer</i> (perhaps derived from the same stock as <i>Microtus +mexicanus</i>), <i>M. (Microtus) xanthognathus</i> (perhaps related to +<i>Microtus chrotorrhinus</i>), <i>M. (Microtus) coronarius</i>, and +<i>M. (Pedomys) ludovicianus</i>.</p> + +<table> + <tr> + <th class="smcap" colspan="2">Species of Which Bacula Were Examined</th> + </tr> + <tr> + <td class="left">Subfamily: Microtinae</td> + <td class="right">Number of Specimens</td> + </tr> + <tr> + <td class="bump1" colspan="2">Tribe: Lemmi</td> + </tr> + <tr> + <td class="bump2"><i>Dicrostonyx groenlandicus</i> (Traill)</td> + <td class="center">4</td> + </tr> + <tr> + <td class="bump2"><i>Lemmus trimucronatus</i> (Richardson)</td> + <td class="center">6</td> + </tr> + <tr> + <td class="bump2"><i>Synaptomys cooperi</i> Baird</td> + <td class="center">5</td> + </tr> + <tr> + <td class="bump1" colspan="2">Tribe: Microti</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Clethrionomys</i> Tilesius, 1850</td> + </tr> + <tr> + <td class="bump3"><i>Clethrionomys rutilus</i> Pallas</td> + <td class="center">4</td> + </tr> + <tr> + <td class="bump3"><i>Clethrionomys gapperi</i> (Vigors)</td> + <td class="center">9</td> + </tr> + <tr> + <td class="bump3"><i>Clethrionomys occidentalis</i> (Merriam)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3"><i>Clethrionomys glareolus</i> Schreber</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3"><i>Clethrionomys rufocanus</i> Sundevall</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Phenacomys</i> Merriam, 1897</td> + </tr> + <tr> + <td class="bump3"><i>Phenacomys intermedius</i> Merriam</td> + <td class="center">5</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Ondatra</i> Link, 1795</td> + </tr> + <tr> + <td class="bump3"><i>Ondatra zibethicus</i> (Linnaeus)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Microtus</i> Schrank, 1798</td> + </tr> + <tr> + <td class="bump3">(<i>Herpetomys</i>) <i>guatemalensis</i> Merriam</td> + <td class="center">3</td> + </tr> + <tr> + <td class="bump3">(<i>Arvicola</i>) <i>richardsoni</i> (DeKay)</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump3">(<i>Chilotus</i>) <i>oregoni</i> (Bachman)</td> + <td class="center">3</td> + </tr> + <tr> + <td class="bump3">(<i>Stenocranius</i>) <i>gregalis</i> (Pallas)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Stenocranius</i>) <i>miurus</i> Osgood</td> + <td class="center">9</td> + </tr> + <tr> + <td class="bump3">(<i>Chionomys</i>) <i>longicaudus</i> (Merriam)</td> + <td class="center">6</td> + </tr> + <tr> + <td class="bump3">(<i>Chionomys</i>) <i>nivalis</i> Martins</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>arvalis</i> (Pallas)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>orcadensis</i> Millais</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>guentheri</i> Danford and Alston</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>fortis</i> Büchner</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>montanus</i> (Peale)</td> + <td class="center">15</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>townsendii</i> (Bachman)</td> + <td class="center">3</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>oeconomus</i> (Pallas)</td> + <td class="center">10</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>mexicanus</i> (Saussure)</td> + <td class="center">13</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>californicus</i> (Peale)</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>pennsylvanicus</i> (Ord)</td> + <td class="center">13</td> + </tr> + <tr> + <td class="bump3">(<i>Microtus</i>) <i>agrestis</i> (Linnaeus)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Pedomys</i>) <i>ochrogaster</i> (Wagner)</td> + <td class="center">41</td> + </tr> + <tr> + <td class="bump3">(<i>Pitymys</i>) <i>pinetorum</i> (LeConte)</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump3">(<i>Pitymys</i>) <i>parvulus</i> (Howell)</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump3">(<i>Pitymys</i>) <i>quasiater</i> (Coues)</td> + <td class="center">5</td> + </tr> + <tr> + <td class="bump3">(<i>Pitymys</i>) <i>fatioi</i> Mottaz</td> + <td class="center">1</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Neofiber</i> True, 1884</td> + </tr> + <tr> + <td class="bump3"><i>Neofiber alleni</i> True</td> + <td class="center">2</td> + </tr> + <tr> + <td class="bump2" colspan="2">Genus: <i>Lagurus</i> Gloger, 1841</td> + </tr> + <tr> + <td class="bump3"><i>Lagurus curtatus</i> (Cope)</td> + <td class="center">7</td> + </tr> + <tr> + <td class="bump4">Total number examined</td> + <td class="center">184</td> + </tr> +</table> + + +<p><span class="pagenum"><a name="Page_193" id="Page_193">[Pg +193]</a></span></p> + +<h2>ACCOUNTS OF SPECIES</h2> + +<h3>Dicrostonyx groenlandicus (Traill)</h3> +<p class="center">Figs. 3 and 4</p> + +<p>Baculum: stalk elongate, greatest length (3.1 mm.) 2 <sup>1</sup>/<sub>5</sub> to 2½ +times greatest breadth, and 4½ times greatest depth; digitate +processes usually cartilaginous, occasionally lateral processes partly +ossified; basal tuberosities weakly to moderately developed, medially +confluent; posterior profile in dorsal view rounded with rounded +posterior apex or shallow notch; dorsal concavity in end-view shallower +and not so wide as ventral concavity; median constriction approximately +<sup>2</sup>/<sub>3</sub> greatest depth; ventral part of base in end-view wider than dorsal +part; shaft straight or slightly curved; base of stalk placed dorsally +relative to axis of shaft; stalk spatulate, sometimes with distal +enlargement; at mid-point stalk wider than high; lateral profile in +dorsal view sloping gradually without abrupt curvature anterior to point +of greatest width.</p> + +<p>The baculum of <i>Dicrostonyx torquatus</i> figured by Ognev +(1948:476) agrees with that of <i>D. groenlandicus</i> in shape of stalk, +and in lateral digitate processes that are small relative to size of +median process; but differs in more elongate, terminally enlarged, bulbar +shape of median process. None of my specimens showed ossification in the +lateral processes, observed by Hamilton (1946:381) in <i>Dicrostonyx +rubricatus richardsoni</i> [ = <i>D. groenlandicus richardsoni</i>]. In +all of my specimens the cartilaginous median process was larger than that +figured by Hamilton, or by Dearden (1958:542).</p> + +<p><i>Specimens examined</i>: Four from; Point Barrow, Alaska, 52524 +(Barrow Village), 67264 (died in captivity); Brooks Range, Alaska, 50536 +(Wahoo Lake, 69°08', 146°58'), 50539 (Porcupine Lake, 68°51'57", +146°29'50", 3140 ft.).</p> + + +<h3>Lemmus trimucronatus (Richardson)</h3> +<p class="center">Fig. 2</p> + +<p>Baculum: Stalk heavy, broad, greatest length (2.8 mm.) in mature +individuals (Fig. 2) as little as 1<sup>1</sup>/<sub>3</sub> times +greatest breadth, greatest length no less than 2<sup>2</sup>/<sub>3</sub> times greatest depth +of base; three ossified processes, median one from as long as to ½ +longer than the lateral processes, and approximately +<sup>2</sup>/<sub>3</sub> wider and twice as deep as lateral processes; +length of median process almost 3½ times its breadth, +approximately ½ length of stalk; basal fossae broadly confluent; +posterior profile in dorsal view evenly rounded; in end-view ventral +concavity deeper than dorsal concavity, constriction as little as +½ greatest depth in mature specimens; shaft straight, bluntly +rounded, or slightly decurved and laterally inflated terminally; lateral +profile in dorsal view a gradual slope from widest point of stalk +anteriorly onto shaft; in younger individuals stalk slenderer, otherwise +as described above.</p> + +<p>Five specimens examined by me differ from one figured and described by +Hamilton (1946:379) in that stalk is better developed, larger relative to +size of processes, length of stalk in my specimen (Fig. 2) 2.8 as opposed +to 2.1 mm. in Hamilton's specimen; median process shorter, 1.5 as opposed +to 1.8 mm., proximal end rounded rather than concave, not partially +enclosing tip of shaft; proportion of and relative sizes of median and +lateral processes approximately same as in Hamilton's <i>Lemmus +helvolus</i> [= <i>Lemmus trimucronatus helvolus</i>]. + +<span class="pagenum"><a name="Page_194" id="Page_194">[Pg +194]</a></span> + +A specimen figured by Dearden (1958:542) has a basally trilobed median +process.</p> + +<p>The baculum of the Asiatic <i>Lemmus lemmus</i> figured by Ognev +(1948:413) agrees with my specimens in the ossification of three +processes, the relative sizes of these processes to each other and to the +stalk, the well-developed base of the stalk and heavy bluntly rounded +shaft; the baculum of <i>Lemmus lemmus</i> differs in greater +anterolateral extent of basal tuberosities, in proximal notch seemingly +separating these tuberosities, and in median process being slenderer.</p> + +<p><i>Specimens examined</i>: Five, of two subspecies; <i>Lemmus +trimucronatus alascensis</i>, Point Barrow, Alaska, numbers 50591, 50678, +50731, 50758; <i>Lemmus trimucronatus subarcticus</i>, Wahoo Lake, +69°08', 146°58', 2350 ft., Brooks Range, Alaska, 50948.</p> + + +<h3>Synaptomys cooperi Baird</h3> +<p class="center">Figs. 5 and 6</p> + +<p>Baculum: Stalk elongate, greatest length (2.7 to 2.8 mm.) 2 +<sup>1</sup>/<sub>3</sub> to 2½ times greatest breadth, 4 to 5 +times greatest depth; three processes ossified or lateral processes +unossified, ossifications relatively small (in 78380, median ossification +less than ¼ as large as lateral ossifications although median +cartilaginous process is larger), length of median process +<sup>1</sup>/<sub>5</sub> to <sup>1</sup>/<sub>6</sub> of length of +stalk, cartilaginous part of median process larger; posterior profile in +dorsal view convex throughout or bilobate; tuberosities moderately +developed, deflected dorsal to axis of shaft; in end-view medial +construction <sup>3</sup>/<sub>5</sub> greatest depth of tuberosities; +shaft tapered from point of greatest width, slightly inflated +terminally.</p> + +<p>The specimen (KU 13716) figured by Hibbard and Rinker (1942:29) has +been restudied. It was first cleared and stained to soften the dry +cartilage binding the digital processes together and to differentiate +bone and cartilage. The lateral processes are small and cartilaginous +(Fig. 6) and seem intact. The differences between this specimen and +others examined by Hamilton (1946:381), Dearden (1958:542), and myself, +namely the relatively larger median ossification, the absence of +ossification in lateral processes, and the distinctly bilobate base and +larger size, may represent geographic differences, or individual +variation. The proportions of length, width, and depth of the stalk, and +the appearance in lateral view do not differ greatly from others examined +by Hamilton, by Dearden (1958:546), and by me.</p> + +<p><i>Specimens examined</i>: Five, representing four subspecies; <i>S. +cooperi gossii</i>, 6 mi. N Midway, Holt Co., Nebraska 78379, 78380; +<i>S. cooperi relictus</i>, 5 mi. N, 2 mi. W Parks, Dundy Co., Nebraska, +72601 (immature); <i>S. cooperi saturatus</i>, 3 mi. S Demotte, Jasper +Co., Indiana, 3-C-454, collection of W. B. Quay; <i>S. cooperi +paludis</i>, Meade County State Park, Kansas, 13716.</p> + + +<h3>Clethrionomys rutilus Pallas</h3> +<p class="center">Fig. 11</p> + +<p>Baculum: Stalk elongate, and proximally enlarged, greatest length (2.7 +mm.) 2 times greatest breadth; less than 4 times greatest depth; three +well-developed ossified processes; length of stalk 2<sup>1</sup>/<sub>3</sub> times length of median process; median process +with basal (and ventral) protuberence and lateral lobes, arched in +dorsoventral plane; lateral processes as large as median process, +flattened distally, having ventromedial vane on distal half; basal +tuberosities of stalk well developed, medially confluent; posterior +profile in dorsal view trilobate or convex + +<span class="pagenum"><a name="Page_195" id="Page_195">[Pg +195]</a></span> + +throughout with rounded posterior apex; dorsal concavity well developed, +ventral surface but slightly concave, medial constriction of base as +little as ½ greatest depth; shaft straight, slender, at mid-point +of stalk but slightly wider than high; basal tuberosities largely dorsal +to axis of shaft in lateral view; lateral profile in dorsal view with an +abrupt curvature separating the gently sloping sides of the shaft from +the basal part at its greatest breadth.</p> + +<p>The specimen of <i>Clethrionomys rutilus</i> figured by Ognev +(1950:120) is essentially like the North American specimens examined by +me in the relative sizes of the ossifications and the general shape of +the stalk.</p> + +<p><i>Specimens examined</i>: Four, of one subspecies; <i>C. r. +dawsoni</i>, west bank Gakona River, 1700 ft., 5 mi. NNE Gulkana, Alaska, +42865, 42866; SW end Dezadeash Lake, 2400 ft., Yukon Territory, 42910, +42921.</p> + + +<h3>Clethrionomys gapperi (Vigors)</h3> +<p class="center">Fig. 10</p> + +<p>Baculum: Stalk elongate, greatest length (2.8 mm.) 1¾ times +greatest breadth, and 3¾ times greatest depth; proximally +enlarged, greatest depth ½ greatest breadth; three well-developed +ossified processes; length of stalk 2 <sup>1</sup>/<sub>3</sub> times +length of median process; median process arched in dorsoventral plane, +with basiventral protuberence or spine and lateral lobes; lateral +processes as large as median process, flattened distally, arched; basal +tuberosities of stalk well developed, medially confluent; posterior +profile in dorsal view trilobate or convex throughout with a rounded +posterior apex; dorsal concavity well developed, ventral surface but +slightly concave, or in some cases slightly convex; medial constriction +of base <sup>3</sup>/<sub>5</sub> greatest depth; shaft straight, +slender, at mid-point of stalk twice as wide as high; basal tuberosities +dorsally placed relative to axis of shaft; lateral profile in dorsal view +abruptly curved anterior to point of greatest width; slender stalk +distinct from angular enlarged base.</p> + +<p>The most noticeable difference between the baculum of <i>C. +rutilus</i> and <i>C. gapperi</i> is size. The proportions of the four +ossifications are approximately the same. Ventral vanes on the lateral +processes are not developed in <i>C. gapperi</i>. <i>C. gapperi</i> and +<i>C. rutilus</i> are more nearly alike in their bacula than any other +two species of <i>Clethrionomys</i> examined. <i>Clethrionomys +occidentalis</i>, the other New World species, is also much like <i>C. +gapperi</i> and <i>C. rutilus</i>. The differences are of a magnitude +comparable to those between the bacula in subspecies of <i>Microtus +montanus</i> (Figs. 19-21) for example, or in subspecies of <i>Lagurus +curtatus</i> (Dearden, 1958:542).</p> + +<p><i>Specimens examined</i>: Nine, of two subspecies; <i>Clethrionomys +gapperi athabascae</i>, British Columbia, 42922 (Indian Creek, Mile Post +234 of Alaskan Highway), 64281 (West bank Racing River, 89 mi. W Muskwa), +64287 (North bank Tetsa River, 56 mi. W, 11 mi. S Muskwa), 64290 (44 mi. +W, 9 mi. S Muskwa), 64310 (32 mi. W, 2 mi. S Muskwa); <i>Clethrionomys +gapperi galei</i>, 31 mi. N Pinedale, Sublette Co., Wyoming, 42108; Grand +Mesa, Delta Co., Colorado, 60014 and 60015 (5½ mi. E, 12 mi. S +Collbran), 60022 (8 mi. E, 1/2 mi. S Skyway).</p> + + +<h3>Clethrionomys occidentalis (Merriam)</h3> +<p class="center">Fig. 12</p> + +<p>Baculum: Stalk elongate, greatest length (2.8 mm.) 2½ times +greatest breadth, 6 times greatest depth; three well-developed ossified +processes; median process larger than lateral processes, ½ the +length of stalk, curved, basally + +<span class="pagenum"><a name="Page_196" id="Page_196">[Pg +196]</a></span> + +broad, ventrally keeled, trilobate posteriorly; lateral ossifications +large, flattened distally, curved; posterior profile of stalk posteriorly +slightly emarginate, thus bilobate in outline; in end-view dorsal +concavity deeper than ventral, constriction less than ½ greatest +depth, tuberosities confluent, visible in dorsal view at each side; shaft +slender, especially in depth, straight; at mid-point of stalk almost +twice as wide as deep, slight terminal inflation.</p> + +<p>The general proportions of the stalk and the relatively large, +uniquely shaped processes, are characteristic of most specimens of the +genus <i>Clethrionomys</i> examined.</p> + +<p><i>Specimen examined</i>: <i>C. occidentalis californicus</i>, one +from Mary's Peak, Benton Co., Oregon, 30, F. W. Sturges' collection.</p> + + +<h3>Clethrionomys glareolus Schreber</h3> +<p class="center">Fig. 13</p> + +<p>Baculum: Stalk elongate, greatest length (2.9 mm.) twice the greatest +breadth in the specimen examined, flattened proximally, greatest length +almost 6 times greatest depth of base; three well-developed ossified +processes; median process arched in a dorsoventral plane, with basal +notch and lateral lobes; lateral processes as long as median process, +bowed in dorsal view, flattened distally, with ventromedial vane; basal +tuberosities of stalk weakly developed, medially confluent; posterior +profile in dorsal view evenly rounded; in end-view dorsal concavity +shallow in comparison to most species but deeper than ventral concavity, +constriction ¾ greatest depth; shaft straight, at mid-point +slightly wider than high, elongate, widest point of stalk less than +¼ of total length from proximal end, slight lateral inflation at +tip; lateral profile in dorsal view sloping at first abruptly and then +gradually from widest point of stalk anteriorly onto shaft.</p> + +<p>The specimen of <i>Clethrionomys glareolus</i> figured by Ognev +(1950:31) in dorsal view as I interpret it, resembles my specimen in the +rounded base; in the elongate, distally inflated shaft; in the initially +abrupt slope of the lateral profile in dorsal view from the greatest +width of stalk anteriorly; and in the presence of three well ossified +processes. Ognev's specimen differs from mine in the median process being +more elongate relative to its width, and rounded proximally, lacking +lateral lobes and basal notch; in lateral processes being less curved; in +the greater terminal inflation of the shaft; and in the closer +approximation of the terminal processes to the shaft. The baculum of +<i>Clethrionomys glareolus</i> as described and figured by Didier +(1954:243-244) resembles my specimen in general proportions, but is more +pointed proximally and more curved in dorsoventral plane. Didier states +that the baculum is rather variable in form in this species, in different +regions, but that a large number of specimens must be examined to assess +the geographic nature of this variation.</p> + +<p><i>Specimen examined</i>: One from Zermatt, Valais, Switzerland, +67100.</p> + + +<h3>Clethrionomys rufocanus Sundevall</h3> +<p class="center">Fig. 9</p> + +<p>Baculum: Base of stalk broad but relatively flattened dorsoventrally, +greatest length (3.2 mm.) less than 1½ greatest width, 4 times +greatest depth; three well-developed ossified processes; median process +arched in dorsoventral plane, having basal notch and lateral lobes; +lateral processes as long as median process, + +<span class="pagenum"><a name="Page_197" id="Page_197">[Pg +197]</a></span> + +flattened distally, with ventromedial vane; basal tuberosities of stalk +weakly developed, medially confluent; posterior profile in dorsal view +convex with rounded posterior apex; dorsal surface of base almost flat, +ventral concavity broad and shallow; constriction ¾ greatest depth +(not including an unusual irregularity on the ventral surface of the +base); shaft straight, at mid-point of stalk distinctly wider than high, +slender at distal end, widest point of stalk almost +<sup>1</sup>/<sub>3</sub> of total length from proximal end, tip of shaft +rounded; lateral profile in dorsal view gradually sloping from widest +point anteriorly onto shaft.</p> + +<p>The specimen of <i>Clethrionomys rufocanus</i> figured by Ognev +(1950:97) resembles my specimen in the presence of three well ossified +processes. Ognev's specimen differs however in the lack of a proximal +notch on the median process, the lesser proportion of the stalk included +in the basal enlargement, the more posterior position of the point of +greatest width, and the presence of a concavity in the posterior profile +of the stalk in dorsal view. These differences in the stalk may be owing +to a difference in age (my specimen perhaps being older).</p> + +<p><i>Specimen examined</i>: One from 1 mi. NW Oho-ri, 6 M., Korea, +60438.</p> + + +<h3>Phenacomys intermedius Merriam</h3> +<p class="center">Figs. 7 and 8</p> + +<p>Baculum: Stalk slender, greatest length (2.9 mm.) 2¼ to +2½ times greatest breadth, 4 times greatest depth; three +well-developed ossified processes, median one almost ½ length of +stalk, curved, broad basally and slightly larger in all dimensions than +either lateral process; lateral processes flattened distally, curved; +base of stalk well developed, basal tuberosities medially confluent or +separated by medial emargination, posterolateral faces flattened or +rough; emarginations in the four adults examined; posterior profile in +dorsal view bluntly pointed or flattened except for emargination +posterially, abruptly curved at point of greatest width; shaft arising +broadly from distal side of base of stalk; in end-view hour-glass shaped, +medial constriction pronounced, both dorsal and ventral concavities deep; +shaft having relatively straight but distally convergent sides; at +mid-point of stalk, 1 to 1½ times as wide as deep; tip bluntly +rounded, or slightly inflated.</p> + +<p>The specimens from Quebec differ from the one from Wyoming in smaller +size, relatively smaller lateral digital processes, larger more medial +basal emargination, and slender shafts. The baculum of <i>Phenacomys +intermedius</i> differs much from that of <i>Phenacomys longicaudus</i>, +described by Hamilton (1946:381) and by Dearden (1958:547). Dearden +states that the three bacula examined by him of <i>Phenacomys +longicaudus</i> differ markedly from the specimen described by Hamilton. +It seems to me that in major features the resemblance is greater between +the specimens of <i>Phenacomys longicaudus</i> examined by these two +authors than between their specimens and specimens of other microtines, +including <i>Phenacomys intermedius</i>. Neither Hamilton nor Dearden +record the exact localities of capture, the collections in which the +specimens are deposited, or the catalogue numbers of specimens. +Consequently verification of identifications and observations is +difficult.</p> + +<p><i>Specimens examined</i>: Five, of two subspecies; <i>P. intermedius +intermedius</i>, 5.4 mi. S Moran, Teton Co., Wyoming, 3-C-309, collection +of W. B. Quay; <i>P. intermedius celatus</i>, four (including one +immature specimen) from Authiernord, + +<span class="pagenum"><a name="Page_198" id="Page_198">[Pg +198]</a></span> + +Abitibi-ouest Co., Quebec, specimens in collection of Bristol Foster +designated by numbers 2041-2044 of S. Anderson's field catalogue. Smith +and Foster (1957:107) were of the view that <i>Phenacomys ungava</i> +(including the above specimens from Quebec) may be specifically distinct +from <i>Phenacomys intermedius</i>.</p> + + +<h3>Ondatra zibethicus (Linnaeus)</h3> +<p class="center">Not figured</p> + +<p>Baculum: In the single specimen examined, less mature than that +figured by Hamilton (1946:384), the digitate processes are cartilaginous, +the basal tuberosities are less well developed, and the shaft is +slenderer throughout. The cartilaginous processes are of the same +proportions as ossified processes in the figure mentioned. The shaft is +also convex ventrally in lateral profile. The view of the side here +considered to be anatomically the ventral side (adjacent to the urethra) +is labelled dorsal view in Hamilton's specimen.</p> + +<p><i>Specimen examined</i>: One, from Reserve, Brown Co., Kansas, 72405.</p> + + +<h3>Microtus (Herpetomys) guatemalensis Merriam</h3> +<p class="center">Figs. 42 and 43</p> + +<p>Baculum: Stalk moderately elongate, greatest length (3.5 mm.) +2<sup>1</sup>/<sub>3</sub> times greatest breadth, spatulate, flattened +throughout, greatest thickness <sup>1</sup>/<sub>3</sub> millimeter; +three ossified processes; median process having three cornered base, +curved dorsally, wider than high, ¼ to <sup>1</sup>/<sub>5</sub> +greatest length of stalk; each lateral process bent at middle, as long as +median process, compressed laterally; base of stalk curved dorsally, +tuberosities marginal, hence narrow, lateral excavations of tuberous +margin not confluent medially; in end-view ventral concavity broad, no +dorsal concavity, medial constriction but slightly less than greatest +thickness (not depth); shaft wider than high throughout, at mid-point +more than 3 times as wide as high; tip of shaft slightly inflated both +laterally and dorsoventrally; lateral profile gradually sloping +anteriorly from widest point of stalk.</p> + +<p>Specimen number 65921 (Fig. 43) differs from number 65895 (Fig. 42) +described above. Terminus of shaft of number 65921 has lateral lobes from +which arise lateral cartilaginous processes; median terminal ossification +irregular in shape, smaller, imbedded in terminally bilobate cartilage. +In the spatulate flattened stalk these two specimens are much alike. An +immature specimen, number 65908, is smaller (length of stalk 2.6 mm.) +also flattened and spatulate, has the terminal processes cartilaginous, +the lateral processes bent medially, and proportions as in the adult.</p> + +<p>The baculum shows no noteworthy resemblance to that of any other +species of North American <i>Microtus</i>; on the other hand the +differences between <i>M. guatemalensis</i> and some other species are no +greater than the differences between certain species included in the +subgenus <i>Microtus</i>. The baculum neither strengthens nor weakens the +case for subgeneric rank for <i>M. (Herpetomys) guatemalensis</i>.</p> + +<p><i>Specimens examined</i>: Three from Guatemala; 65895 (2 mi. S San +Juan Ixcoy), 65908, (3-1/2 mi. SW San Juan Ixcoy), 65921 (10 mi. E, 4 mi. +S Totonicapán).</p> + +<p><span class="pagenum"><a name="Page_199" id="Page_199">[Pg +199]</a></span></p> + + +<h3>Microtus (Arvicola) richardsoni (DeKay)</h3> +<p class="center">Figs. 38 and 39</p> + +<p>Baculum: Stalk broad, greatest length (3.7 to 4.3 mm.) 1½ times +greatest breadth, relatively flattened, greatest depth +<sup>1</sup>/<sub>3</sub> greatest breadth; single median ossified +process, in smaller of two specimens this ossification incomplete and of +unusual shape (Fig. 39); length of stalk 4 times length of median +process; concavities of basal tuberosities medially confluent, +constriction less than ½ greatest depth; widest point of shaft +less than ¼ length of shaft from posteriormost point; shaft wider +than high except at distal end that is inflated dorsally and sometimes +laterally; both ventral and dorsal concavities of base of stalk broad and +moderately deep; posterior profile in dorsal view evenly rounded or +having marginal notch.</p> + +<p>In the absence of ossified lateral processes my two specimens differ +from bacula of <i>Microtus (Arvicola) terrestris</i> figured by Didier +(1943:79, 1954:245, 247, 248) and by Ognev (1950:591). The median process +relative to the size of the shaft is smaller, and the shaft relative to +its length is wider in <i>M. richardsoni</i> than in <i>M. +terrestris</i>. The stalk of <i>M. (Arvicola) amphibius</i> figured by +Didier is like that of <i>M. richardsoni</i> in its greater breadth and +median notch on posterior border.</p> + +<p>The relationship of the New World water rat, <i>M. richardsoni</i>, to +the Old World water rats (genus <i>Arvicola</i> of some European authors) +is uncertain. Miller (1896:66) placed all of them in the subgenus +<i>Arvicola</i>. Subsequent authors, stressing differences in the teeth, +have placed <i>M. richardsoni</i> in the subgenus <i>Aulacomys</i> of +Rhoads. Zimmerman (1955) has shown that teeth in some <i>Arvicola</i> +approach the more complex pattern of <i>M. richardsoni</i>. He argues +also that <i>Arvicola</i> is generically distinct from <i>Microtus</i> on +the grounds that the two groups have separate origins, <i>Arvicola</i> +having descended from the genus <i>Mimomys</i> and <i>Microtus</i> from +some other group of microtines. This argument also was advanced by Hinton +(1926:47-48). Pending further studies of the possible polyphyletic origin +of other subgenera of the genus <i>Microtus</i>, I refer both <i>M. +richardsoni</i> and <i>M. terrestris</i> to the subgenus <i>Arvicola</i>.</p> + +<p>The evidence afforded by the bacula available is not conclusive as to +relations of Old World and New World water rats. No general agreement on +the number of species in this Palaearctic group has been reached, and +bacula of only three or four of the numerous Old World subspecies have +been figured. I have examined none.</p> + +<p><i>Specimens examined</i>: Two, from Wyoming; 42454 (31 mi. N +Pinedale, 8025 ft., Sublette Co.), 37903 (23-1/2 mi. S, 5 mi. W Lander, +8600 ft., Fremont Co.).</p> + + +<h3>Microtus (Chilotus) oregoni (Bachman)</h3> +<p class="center">Fig. 45</p> + +<p>Baculum: Stalk broad, greatest length (2.2 mm.) 1¾ times +greatest breadth, 3½ times greatest depth; three well-developed +ossified processes; median process <sup>2</sup>/<sub>5</sub> length of +stalk, rounded or tapered terminally, proximal end opposed to tip of +stalk and flattened obliquely; lateral processes +<sup>2</sup>/<sub>3</sub> length of median process, deeper than wide, +curved; tuberosities of stalk well developed, confluent medially, visible +in dorsal view; in end-view dorsal concavity narrow, moderately + +<span class="pagenum"><a name="Page_200" id="Page_200">[Pg +200]</a></span> + +deep, rounded, ventral concavity wide, deep, flattened; base wider +ventrally than dorsally; shaft tapering more or less uniformly, +terminally inflated.</p> + +<p>In the relative sizes, to each other and to the stalk, of the three +digitate ossifications <i>M. oregoni</i> resembles closely the Old World +representative of the same subgenus, <i>M. (Chilotus) socialis</i>, as +figured by Argyropulo (1933b:181). In <i>M. oregoni</i> the greatest +width of the baculum is more proximal on the stalk than in the <i>M. +socialis</i> figured by Argyropulo but closely resembles the baculum of +the <i>M. socialis</i> figured by Didier (1954:242). In possessing a +shallow emargination in the base of the stalk and in possessing a median +process that is smaller than the lateral processes, <i>M. socialis</i>, +as figured by Didier, differs from <i>M. oregoni</i>. The baculum figured +by Argyropulo (<i>loc. cit.</i>) of <i>Sumeriomys colchicus +schidlovskii</i> [ = <i>Microtus (Chilotus) socialis schidlovskii</i> +according to Ognev, 1950:392] differs from other <i>Chilotus</i> that +have been studied in having an unusually elongate median process and a +more distal placement of the widest part of the stalk.</p> + +<p><i>Specimens examined</i>: Three, of the subspecies <i>M. oregoni +oregoni</i>, from 5 mi. N Orick, Humboldt Co., California, 3-C-248, +collection of W. B. Quay; from Mary's Peak, Benton Co., Oregon, 66, +collection of F. W. Sturges; and from Sec. 3, T. 11S, R. 5W, Benton Co., +Oregon, 79183.</p> + + +<h3>Microtus (Stenocranius) gregalis (Pallas)</h3> +<p class="center">Fig. 34</p> + +<p>Baculum: Length of stalk (2.4 mm.) 1¾, times greatest breadth, +4<sup>1</sup>/<sub>3</sub> times greatest depth; median ossified process +well developed, more than <sup>1</sup>/<sub>3</sub> length of stalk, +higher than wide, slightly bowed, closely appressed to terminus of shaft; +basal tuberosities of stalk moderately developed, confluent medially, +posterior profile of medial apex rounded in dorsal view, lateral +indentations present, hence trilobate outline; in proximal end-view base +wider ventrally, ventral concavity broader than dorsal concavity but of +equal depth, medial constriction <sup>2</sup>/<sub>3</sub> greatest +depth; shaft slender in distal part, inflated terminally, and wider than +high at mid-point of stalk; lateral profile a smooth slope of gradually +decreasing curvature from point of greatest width to near distal end.</p> + +<p>The baculum of this species figured by Ognev (1950:461) differs in +having lateral ossified processes, and a more rounded base of the stalk. +Resemblance to the New World <i>Stenocranius</i> is discussed below.</p> + +<p><i>Specimen examined</i>: One from "Eastern Europe," 8059.</p> + + +<h3>Microtus (Stenocranius) miurus Osgood</h3> +<p class="center">Figs. 32 and 33</p> + +<p>Baculum: Length of stalk (2.8 mm.) 1½ times greatest breadth, +3½ times greatest depth; median process ossified, +<sup>2</sup>/<sub>5</sub> to <sup>3</sup>/<sub>5</sub> length of stalk, +laterally compressed, sometimes arched in dorsoventral plane; lateral +processes cartilaginous, slender; basal tuberosities well developed, +averaging less enlarged than shown in Figure 32, but more angular in +lateral outline than shown in Figure 33; tuberosities confluent +posteriorly; posterior profile smoothly rounded to trilobate, curvature +at point of greatest breadth usually acute; in proximal end-view base +wider dorsally, deep dorsal concavity, shallow ventral concavity, medial +constriction <sup>3</sup>/<sub>5</sub> of greatest depth; shaft slender +anteriorly, at mid-point of stalk + +<span class="pagenum"><a name="Page_201" id="Page_201">[Pg +201]</a></span> + +twice as wide as high, at tip higher than wide, laterally inflated; +lateral profile in most specimens abruptly curved anterior to point of +greatest breadth.</p> + +<p>The single specimen of the Old World <i>M. (Stenocranius) gregalis</i> +examined resembles the New World <i>M. (Stenocranius) miurus</i> in the +angular lateral profile at the point of greatest breadth of the stalk, +slender shaft in comparison to broad base of stalk, and presence of a +single well-developed laterally compressed median process. The base of +the stalk in the baculum of <i>M. gregalis</i> is less well developed and +smaller than in the baculum of <i>M. miurus</i>.</p> + +<p><i>Specimens examined</i>: Nine, all of the subspecies <i>Microtus +miurus muriei</i>, from the Brooks Range, Alaska; 51077 (Lake Schrader, +145°09'50", 69°24'28", 2900 ft., Romanzof Mts.); 51151, 51152, +51154, 51164, 51166, 51169 (last 6 from Wahoo Lake, 69°08', +146°58', 2350 ft.); 51210, 51213 (last 2 from Porcupine Lake, +68°51'57", 146°29'50", 3140 ft.).</p> + + +<h3>Microtus (Chionomys) nivalis Martins</h3> +<p class="center">Fig. 47</p> + +<p>Baculum: Greatest length of stalk (2.7 mm.) 2¼ times greatest +breadth, 4½ times greatest depth; three digitate processes, +lateral processes mostly cartilaginous in single adult examined; median +process well ossified, approximately <sup>1</sup>/<sub>3</sub> length of +stalk, basally notched, not arched, laterally compressed distally; base +of stalk broad and flat, basal tuberosities well developed, separate; +posterior profile in dorsal view rounded, convex except for medial notch +separating tuberosities; dorsal and ventral concavities deep, broad, +equal; medial constriction less than ½ greatest depth; in dorsal +view shaft tapering gradually from widest point, terminally rounded; at +mid-point of stalk almost twice as wide as high.</p> + +<p>In the elongate, largely cartilaginous lateral processes of the +baculum, the specimen described above resembles <i>M. longicaudus</i>. +The size of the median process in comparison to the size of the stalk is +also the same. The lateral processes have larger ossifications and the +base of the stalk is more robust in <i>M. longicaudus</i> than in <i>M. +nivalis</i>.</p> + +<p>The well ossified lateral processes and enlarged base of Didier's +(1954:240) specimen suggest that it is of a more mature individual than +the one described above. These specimens of <i>M. nivalis</i>, as well as +the specimens of <i>M. longicaudus</i>, exhibit dorso-ventral flattening +of the mid-part of the base of the stalk.</p> + +<p>The baculum of a specimen from Switzerland is weakly developed, of +small size (shaft 2.0 mm. in length), slender, thin, spatulate, and +terminally inflated. Digital processes were not observed, perhaps owing +to excessive maceration in preparation. The general appearance of the +baculum is that of an immature individual, although the animal was not +small (165 mm. total length in preservative).</p> + +<p><i>Specimens examined</i>: Two <i>Microtus nivalis nivalis</i>; +Zermatt, Valais, Switzerland, 67105; Wetterstein, Germany, 65127.</p> + + +<h3>Microtus (Chionomys) longicaudus (Merriam)</h3> +<p class="center">Fig. 48</p> + +<p>Baculum: Base of stalk well developed, greatest length (3 mm.) +1¾ times greatest breadth, 3<sup>2</sup>/<sub>3</sub> times +greatest depth; three ossified processes; base of median process rounded; +median process slightly curved in dorsoventral plane, in length almost +<sup>1</sup>/<sub>3</sub> greatest length of stalk; ossifications in +lateral processes + +<span class="pagenum"><a name="Page_202" id="Page_202">[Pg +202]</a></span> + +variable in size, frequently widely separated from shaft by cartilage, +rarely as large as median ossification; basal tuberosities usually +well-developed, medially confluent; profile of base in dorsal view +trilobate or irregularly convex throughout; constriction ½ +greatest depth; shaft relatively straight or slightly bowed ventrally or +dorsally, shaft at mid-point of stalk wider than high; tip of shaft +laterally inflated; widest point of stalk approximately ¼ length +of stalk from proximal end; lateral profile in dorsal view tapers +gradually onto shaft anteriorly from point of greatest width of stalk; +shaft variable, from slender terminally and nearly parallel sided (Fig. +48), to broad distally and tapered.</p> + +<p>In many of the features that distinguish <i>M. longicaudus</i> (and +the closely related insular species <i>M. coronarius</i>) from other +North American <i>Microtus</i>, <i>longicaudus</i> resembles the Old +World species of the subgenus <i>Chionomys</i> (that is to say, <i>M. +nivalis</i>, <i>M. gud</i>, and <i>M. roberti</i>). These features are +medium size, long tail, grayish color, montane habitat, relatively short +molar tooth-row, moderate sized and unconstricted incisive foramen, +relatively decurved upper incisors, elongate nasals, relatively broad +interorbital region without well-developed median ridge, and similar +chromosomes (Matthey, 1955:178). For these reasons I am here referring +<i>Microtus longicaudus</i> to the subgenus <i>Chionomys</i>; previously +it has not been referred to that subgenus.</p> + +<p><i>Specimens examined</i>: Six, of three subspecies; <i>Microtus +longicaudus littoralis</i>, Sullivan Island, Alaska, 42972, 42969; <i>M. +l. mordax</i>, 3/4 mi. N, 2 mi. W Allenspark, 8400 ft., Boulder Co., +Colorado, 50335, 76829; <i>M. l. sierrae</i>, Crane Flat, Mariposa Co., +California, 50252, 50253.</p> + + +<h3>Microtus arvalis (Pallas)</h3> +<p class="center">Fig. 22</p> + +<p>Baculum: In the single specimen examined, stalk small, greatest length +(2.3 mm.) 2<sup>1</sup>/<sub>3</sub> times greatest width, almost 6 times +greatest depth, flattened proximally; three well-developed digitate +processes, the median one ossified, the lateral processes cartilaginous; +median ossification laterally compressed and decurved at tip, bilobate at +base; basal tuberosities of stalk weakly developed, medially confluent; +posterior profile in dorsal view evenly rounded; ventral concavity deeper +and narrower than dorsal concavity, but both comparatively shallow; +medial constriction <sup>2</sup>/<sub>3</sub> greatest depth; shaft +straight, at mid-point twice as wide as deep; lateral profile tapering +from greatest width gradually to parallel sides of distal third of +stalk.</p> + +<p>From the baculum of <i>Microtus arvalis</i> figured by Ognev +(1950:173), and from the baculum figured by Didier (1954:238) my specimen +differs in the absence of lateral ossifications in the digitate +processes, smaller and slenderer median ossification, and weaker base. +These differences in part may be owing to a difference in age, my +specimen being the less mature.</p> + +<p><i>Specimen examined</i>: One from Vidy, Switzerland, 67101.</p> + + +<h3>Microtus orcadensis Millais</h3> +<p class="center">Fig. 24</p> + +<p>Baculum: In the one specimen examined, stalk broad, greatest length +(2.6 mm.) 1½ times greatest breadth, 3½ times greatest +depth; three digitate processes ossified; median process relatively +broad, in length more than ½ length of stalk, triangular in dorsal +view, with small spurs posterolaterally, + +<span class="pagenum"><a name="Page_203" id="Page_203">[Pg +203]</a></span> + +middorsal ridge posteriorly; lateral ossifications slightly curved, +slenderer, less than ½ depth and less than ½ transverse +thickness of median process; basal tuberosities well-developed, confluent +medially; in end-view base wider dorsally than ventrally, dorsal +concavity broader and more abruptly curved at mid-point than ventral +concavity; constriction ½ greatest depth; posterior profile in +dorsal view notched, setting off a posterior shelf; stalk including shaft +wider than deep throughout, at mid-point width twice depth; lateral +profile abruptly curved anterior to point of greatest width, sides of +shaft tapering gradually anteriorly to rounded uninflated tip.</p> + +<p>The baculum of this insular species, placed in the "<i>arvalis</i>" +group by Ellerman (1941:595), resembles the baculum of both <i>Microtus +agrestis</i> and <i>Microtus guentheri</i> more than it resembles the +baculum of <i>Microtus arvalis</i>. Similarities in the chromosomes of +<i>M. arvalis</i> and <i>M. orcadensis</i> were noted by Matthey +(1953:254, 279), who was of the opinion that <i>M. orcadensis</i> is an +insular derivative of the <i>arvalis</i>-group.</p> + +<p><i>Specimen examined</i>: One from the Orkney Islands, 67106.</p> + + +<h3>Microtus guentheri Danford and Alston</h3> +<p class="center">Fig. 23</p> + +<p>Baculum: In the one specimen examined, stalk broad, greatest length +(2.9 mm.) 1½ times greatest breadth, 3½ times greatest +depth; three digitate processes ossified; median process slightly less +than ½ length of stalk, broad, dorsally curved; curved lateral +ossifications shorter and more slender than median ossification; basal +tuberosities well developed, angular, confluent across posterior border +of projecting shelf; in end-view tuberosities projecting ventrolaterally +from central shelf; dorsal surface at medial constriction flat, ventral +surface broadly and deeply concave; posterior profile in dorsal view +trilobate, central lobe formed by posteriorly flattened shelf, surface of +attachment visible only on lateral lobes; at mid-point stalk almost twice +as wide as deep, depth of shaft greater than width proximal to inflated +terminus.</p> + +<p><i>Specimen examined</i>: One from Palestine, 67104.</p> + + +<h3>Microtus fortis Büchner</h3> +<p class="center">Fig. 25</p> + +<p>Baculum: Stalk large, greatest length (3.8 mm.) +1<sup>4</sup>/<sub>5</sub> times greatest breadth, 4½ times +greatest depth; three digitate processes ossified; median ossification +almost <sup>1</sup>/<sub>3</sub> length of stalk; lateral ossifications +slender, smaller than median ossification; posterior profile of stalk in +dorsal view trilobate, basal tuberosities well developed, confluent +medially; in end-view dorsal concavity broader and deeper than ventral +concavity; medial constriction pronounced (less than ½ greatest +depth); lateral profile at widest point of stalk convex, becoming +abruptly concave as the flange of the basal tuberosities grades into the +shaft, then gradually converging to narrowest point +<sup>1</sup>/<sub>3</sub> of length of stalk from the terminus; stalk +wider than deep in proximal <sup>2</sup>/<sub>3</sub>, circular in cross +section in terminal <sup>1</sup>/<sub>3</sub>, slight terminal +inflation.</p> + +<p>A specimen figured by Ognev (1950:297) has the same general +proportions, slender lateral processes, and proximal placement of the +point of greatest breadth.</p> + +<p><i>Specimens examined</i>: Two from Chipo-ri, Korea, 60443, 63841.</p> + +<p><span class="pagenum"><a name="Page_204" id="Page_204">[Pg +204]</a></span></p> + + +<h3>Microtus montanus (Peale)</h3> +<p class="center">Figs. 19, 20 and 21</p> + +<p>Baculum: Stalk broad, greatest length (varying with subspecies from +2.3 to 3.1 mm.) 1½ to 1¾ times greatest breadth, +3<sup>1</sup>/<sub>3</sub> to 4<sup>1</sup>/<sub>3</sub> times greatest +depth; three ossified processes, median one largest, more than twice as +wide and as deep as shorter, slenderer, lateral processes; median process +laterally compressed distally except in one specimen in which moderately +inflated distally, proximally enlarged in some specimens (Fig. 21) and +<sup>1</sup>/<sub>3</sub> to <sup>2</sup>/<sub>5</sub> length of stalk; +base broad, posterior profile in dorsal view evenly convex throughout, at +widest point of stalk abruptly incurved; basal tuberosities moderately to +strongly developed, medially confluent; in end-view base wider ventrally +than dorsally, dorsal concavity slightly to much deeper than the nearly +flattened ventral concavity; medial constriction +<sup>2</sup>/<sub>3</sub> to <sup>4</sup>/<sub>5</sub> of greatest depth; +shaft relatively slender, at mid-point of stalk slightly wider than high +and ¼ as wide as base of stalk, terminally rounded or slightly +inflated; lateral profile in dorsal view a gradual curve from point of +greatest width anteriorly onto shaft.</p> + +<p>The different subspecies figured show the essential characteristics of +the species, differing primarily in size.</p> + +<p><i>Specimens examined</i>: Fourteen, of three subspecies; <i>Microtus +montanus amosus</i>, ½ mi. E Soldier Summit, Wasatch Co., Utah, +62241; <i>M. montanus fusus</i>, La Manga Pass, Conejos Co., Colorado, +42164; 5 mi. N, 26 mi. W Saguache, 9500 ft., Saguache Co., Colorado, +42307, 42315; 5 mi. N, 27 mi. W Saguache, 9350 ft., Saguache Co., +Colorado, 42308; 5 mi. N, 28 mi. W Saguache, 9325 ft., Saguache Co., +Colorado, 42309; 5 mi. S, 24 mi. W Antonito, 9600 ft., Conejos Co., +Colorado, 42327, 42330; Prater Canyon, Mesa Verde National Park, +Montezuma Co., Colorado, 69456, 69457, 69463; <i>Microtus montanus +nanus</i>, 2 mi. N, 2 mi. W Pocatello, Bannock Co., Idaho, 57470, 57472; +¼ mi. N, 2 mi. W Allenspark, 8400 ft., Boulder Co., Colorado, +50330.</p> + + +<h3>Microtus townsendii (Bachman)</h3> +<p class="center">Fig. 41</p> + +<p>Baculum: Stalk broad, greatest length (3.0 mm.) 1½ times +greatest breadth, 4½ times greatest depth; three ossified +processes, median one largest, deeper and more than twice as wide as +curved, shorter, compressed lateral processes and more than +<sup>2</sup>/<sub>5</sub> as long as stalk; base broad, in dorsal view +posterior profile trilobate, basal tuberosities visible; basal +tuberosities well developed, medially confluent; in end-view base wider +ventrally than dorsally, dorsal concavity deeper than ventral concavity; +medial constriction <sup>3</sup>/<sub>5</sub> of greatest depth; shaft +broad, at mid-point more than twice as wide as high and +<sup>1</sup>/<sub>3</sub> as wide as base of stalk, terminally +rounded.</p> + +<p><i>Specimens examined</i>: Three, all <i>M. t. townsendii</i>; Fort +Lewis, Pierce Co., Washington, 57998, subadult; Sec. 33, T. 11S, R. 5W, +Benton Co., Oregon, 79186; Sec. 5, T. 12S, R. 4W, Benton Co., Oregon, +79188.</p> + + +<h3>Microtus oeconomus (Pallas)</h3> +<p class="center">Fig. 44</p> + +<p>Baculum: Stalk broad and flattened, greatest length (3.5 mm.) +1<sup>2</sup>/<sub>3</sub> to 2 times greatest width, 4 to 5½ +times greatest depth; three ossified processes, median one largest, +lateral processes slender, relatively small; length of median process +<sup>3</sup>/<sub>8</sub> length of stalk; median process decurved, +dorsoventrally flattened in + +<span class="pagenum"><a name="Page_205" id="Page_205">[Pg +205]</a></span> + +some specimens, widened at base; attachment of processes to shaft +displaced ventrally; base of stalk widened, posterior profile in dorsal +view usually trilobate, in a few cases rounded, median lobe forming +posterior shelf, lateral lobes dorsally raised and forming margins of +lateral tuberosities; in end-view thickness frequently more or less +uniform throughout central part, broad depression dorsally, ventral +concavity narrower and shallower (as figured); base, and occasionally +shaft, flattened, width at mid-point of stalk 2 to 3 times depth, +narrowest point posterior to terminal inflation of shaft in terminal +<sup>1</sup>/<sub>3</sub> of shaft.</p> + +<p>The baculum of <i>M. oeconomus</i> (Old World) figured by Ognev +(1950:257) resembles but exceeds that of <i>M. oeconomus</i> (New World) +in the relatively large median process and slender lateral processes, but +differs noticeably in the presence of a deep median notch in the base of +the stalk. A specimen from Hungary is intermediate between Ognev's +specimen and those from the New World in both size of median process and +size of lateral processes, and has an unnotched base resembling that in +Figure 44.</p> + +<p><i>Specimens examined</i>: Ten, of three subspecies; <i>M. oeconomus +gilmorei</i>, Umiat, Alaska, 51354, 51361, 51399, 51408; Lake Schrader, +Brooks Range, Alaska, 51422; <i>M. o. macfarlani</i>, 5 mi. NNE Gulkana, +Alaska, 43039, 43041; 20 mi. NE Anchorage, Alaska, 43044; Kelsall Lake, +British Columbia, 43048; <i>M. o. mehelyi</i>, Kisbalatan, Hungary, +75159.</p> + + +<h3>Microtus mexicanus (Saussure)</h3> +<p class="center">Figs. 35 and 36</p> + +<p>Baculum: Stalk attenuate, greatest breadth relatively near proximal +end; greatest length (3.1 to 3.4 mm.) more or less twice greatest +breadth, 4 to 5 times greatest depth; usually a single process ossified; +lateral processes relatively small, cartilaginous or (in three specimens, +63094, 69453, 68019) with small ossifications; median process relatively +small, sometimes appressed to tip of shaft, in length less than ¼ +length of stalk; posterior profile in dorsal view rounded, flattened +posteriorly, or in some specimens trilobate with angular edges; in +end-view relative depths of dorsal and ventral concavities variable, +dorsal usually deeper than ventral; distal end of stalk frequently bowed +dorsally; shaft slender distally, sometimes slightly inflated terminally, +or (in one specimen, 63085) near tip small lateral projections that are +perhaps fused lateral ossifications; lateral profile in dorsal view a +gradual slope anteriorly from point of greatest width to slender tip.</p> + +<p><i>Specimens examined</i>: Thirteen, of four subspecies; <i>Microtus +mexicanus mexicanus</i>, Las Vigas, Veracruz, 30692; Nevada de Toluca, +México, 63101; Valle de Bravo, México, 63094; <i>Microtus mexicanus +mogollonensis</i>, Mt. Taylor, Valencia Co., New Mexico, 63298, 76830; +Park Well, Mesa Verde National Park, Montezuma Co., Colorado, 69448, +69453; Upper Nutria, McKinley Co., New Mexico, 69997, 70000; <i>Microtus +mexicanus phaeus</i>, Sierra Patamba, 9000 ft., Michoacán, 63085; +<i>Microtus mexicanus subsimus</i>, 2 mi. E Mesa de Tablas, Coahuila, +58916; 13 mi. E San Antonio de las Alazanas, Coahuila, 68019, 68021.</p> + + +<h3>Microtus californicus (Peale)</h3> +<p class="center">Fig. 37</p> + +<p>Baculum: Stalk elongate, greatest length (3.0 mm.) +2<sup>1</sup>/<sub>3</sub> times greatest breadth, 4½ times +greatest depth; median process ossified, ¼ length of stalk, +basally broadened, flattened and shallowly grooved ventrally to fit tip +of shaft, to which the process is closely appressed; lateral processes +cartilaginous; ends + +<span class="pagenum"><a name="Page_206" id="Page_206">[Pg +206]</a></span> + +of stalk bowed upwardly; posterior profile of base of stalk rounded or +slightly trilobate if posterolateral concavities form in tuberosities; +moderate development of tuberosities, in end-view dorsal concavity +slightly deeper and narrower than ventral concavity, both comparatively +shallow, median constriction <sup>4</sup>/<sub>5</sub> greatest depth; +shaft curved, more or less terete at mid-point of stalk, terminally +inflated dorsally; lateral profile in dorsal view gradually curved from +point of greatest width anteriorly onto shaft.</p> + +<p><i>Specimens examined</i>: Two, of two subspecies; <i>Microtus +californicus californicus</i>, 1 mi. NE Berkeley, in Contra Costa Co., +California, 76828; <i>Microtus californicus mohavensis</i>, ½ mi. +SE Victorville, San Bernardino Co., California, 63745.</p> + + +<h3>Microtus pennsylvanicus (Ord)</h3> +<p class="center">Figs. 14, 15, 16 and 17</p> + +<p>Baculum: Stalk heavy, broad, greatest length (2.2 to 3.0 mm.) +1<sup>1</sup>/<sub>3</sub> to 1<sup>2</sup>/<sub>3</sub> times greatest +breadth, up to 3¾ times greatest depth; three ossified processes, +median one largest, usually not twice so deep as lateral ossifications; +median process usually distinctly widened basally, in length +approximately ½ length of stalk; base broad, frequently angular +laterally and basally, sometimes bilobate; basal tuberosities well +developed, medially confluent; in end-view more or less uniformly +biconvex or ventral surface more flattened than dorsal surface, medial +constriction ½ to <sup>2</sup>/<sub>3</sub> greatest depth; shaft +relatively heavy, at mid-point stalk almost twice as wide as deep and +<sup>1</sup>/<sub>3</sub> as wide as base of stalk; shaft terminally +rounded and sometimes slightly inflated; lateral profile in dorsal view +abruptly or gradually curved anterior to point of greatest width and then +gradually curved anteriorly.</p> + +<p>Specimens examined averaged slightly smaller and were more variable +than those described by Hamilton (1946:382). The greater variation may be +in part geographic, as five subspecies are represented. Lateral processes +are the last to ossify. One specimen (75082) with well-ossified median +process lacks any lateral ossification. Four bacula of <i>M. +pennsylvanicus</i> (locality not specified) studied by Dearden (1958:547) +agree in general with the description above.</p> + +<p>One specimen shows a break, perhaps resulting from injury, in the +shaft (Fig. 14). One specimen has a posteromedian spine on the median +digital ossification (Fig. 16). Comparison with <i>M. agrestis</i> is +included with the description of <i>M. agrestis</i>.</p> + +<p><i>Specimens examined</i>: Thirteen, of six subspecies; <i>Microtus +pennsylvanicus alcorni</i>, 20 mi. NE Anchorage, Alaska, 43043; +<i>Microtus pennsylvanicus finitus</i>, Laird, Yuma Co., Colorado, 68544; +<i>Microtus pennsylvanicus modestus</i>, 5 mi. N, 26 mi. W Saguache, 9500 +ft., Saguache Co., Colorado, 42306; 3 mi. N, 16 mi. W Saguache, 8500 ft., +Saguache Co., Colorado, 42416, 42417, 42418; 1 mi. S, 2 mi. E Eagle Nest, +8100 ft., Colfax Co., New Mexico, 42430, 42439; <i>Microtus +pennsylvanicus pennsylvanicus</i>, 2 mi. S, 3 mi. E Ft. Thompson, 1370 +ft., Buffalo Co., South Dakota, 42379; Vermillion, Clay Co., South +Dakota, 37070; <i>Microtus pennsylvanicus pullatus</i>, 12 mi. S, 5 mi. E +Butte, Silver Bow Co., Montana, 57501, 57503; <i>Microtus pennsylvanicus +uligocola</i>, Muir Springs, 2 mi. N, 2½mi. W Ft. Morgan, Morgan +Co., Colorado, 75082.</p> + + +<h3>Microtus agrestis (Linnaeus)</h3> +<p class="center">Fig. 18</p> + +<p>Baculum: Greatest length of stalk (2.9 mm.) twice greatest breadth, +4½ times greatest depth; stalk well developed, shaft not flattened +dorsoventrally; large median ossified process, minute lateral +ossifications in single specimen + +<span class="pagenum"><a name="Page_207" id="Page_207">[Pg +207]</a></span> + +examined; length of stalk 2½ times length of median ossification +which is higher than wide, slightly decurved, sagittate in dorsal view, +with three-cornered base; basal tuberosities of stalk moderately well +developed, medially joined; posterior profile in dorsal view evenly +rounded; ventral concavity broader than, but of comparable depth to, +dorsal concavity in end-view, base of stalk wider ventrally, constriction +¾ greatest depth; at mid-point of stalk shaft is but slightly +wider than high; pronounced terminal inflation of shaft; lateral profile +in dorsal view sloping abruptly from widest point of stalk anteriorly +onto stalk which then tapers more gradually to terminal inflation.</p> + +<p>From the baculum of its New World counterpart, namely <i>Microtus +pennsylvanicus</i>, my specimen of <i>Microtus agrestis</i> and the +specimen figured by Didier (1954:239) differ in their minute lateral +processes, relatively larger median processes, and more elongate, less +dorsoventrally flattened shafts.</p> + +<p>The specimen of <i>M. agrestis</i> figured by Ognev (1950:320), in +dorsal view has lateral concavities producing a somewhat trilobate +outline in the base of the stalk, and the lateral processes are well +developed; the median process is larger and bulbous, wider distally than +proximally. Without larger numbers of bacula of <i>M. agrestis</i> I am +unable to reconcile these differences. The differences between <i>M. +agrestis</i> and <i>M. pennsylvanicus</i> seem comparable to the +differences between some other species of <i>Microtus</i>.</p> + +<p><i>Specimen examined</i>: One, from Gryon, Switzerland, 67102.</p> + + +<h3>Microtus (Pedomys) ochrogaster (Wagner)</h3> +<p class="center">Fig. 31</p> + +<p>Baculum: Stalk broad, greatest length (3.2-4.0 mm.) +1<sup>2</sup>/<sub>3</sub> to 2 times greatest breadth, 2½ to 4 +times greatest depth; median process ossified, relatively small, less +than <sup>3</sup>/<sub>10</sub> length of stalk; lateral processes +arising from subterminal part of stalk, cartilaginous or with small +ossifications; posterior profile in dorsal view broadly rounded or +slightly angular, widest point of stalk <sup>1</sup>/<sub>6</sub> to +¼ the length of stalk from base; basal tuberosities well developed +and medially confluent, in end-view dorsally convex, or at least less +deeply concave than ventrally; shaft straight, base bent ventrally or +more commonly dorsally; at mid-point of stalk wider than high, often +twice as wide as high; viewed from above, lateral profile from point of +greatest breadth to middle of shaft a gradual sigmoid curve; slight +terminal inflation of shaft.</p> + +<p><i>Specimens examined</i>: Forty-one, of three subspecies; <i>Microtus +ochrogaster haydeni</i>, Muir Springs, 2 mi. N, 2½ mi. W Ft. +Morgan, Morgan Co., Colorado, 74995, 74998, 74999, 75002; 1 mi. W Laird, +Yuma Co., Colorado, 57304, 76833; 2 mi. N, 2 mi. W Haigler, Dundy Co., +Nebraska, 75016; 2 mi. S Franklin, Franklin Co., Nebraska, 75043, 75044; +Atwood, Rawlins Co., Kansas, 75020, 75023, 75025, 75027, 75028; 1 mi. N, +2 mi. E Oberlin, Decatur Co., Kansas, 75030, 75032, 75034, 75035, 75036; +1½ mi. N, ¼ mi. E Norton, Norton Co., Kansas, 68327; 1 mi. +SW Norton, Norton Co., Kansas, 75037; 2 mi. S, 1 mi. W Norton, Norton +Co., Kansas, 75038; <i>M. ochrogaster ochrogaster</i>, Rydal, Republic +Co., Kansas, 75047-75053, 75060, 75062, 75063, 75066, 75070, 75071, +75073; 1 mi. N, 1 mi. W Holton, Jackson Co., Kansas, 75077; 2 mi. W Court +House, Lawrence, Douglas Co., Kansas, 76832; Univ. Kansas Natural History +Reservation, Douglas Co., Kansas, 68536; <i>M. ochrogaster taylori</i>, +Meade County State Park, Kansas, 68539, 68542.</p> + +<p><span class="pagenum"><a name="Page_208" id="Page_208">[Pg +208]</a></span></p> + + +<h3>Microtus (Pitymys) pinetorum (LeConte)</h3> +<p class="center">Figs. 27 and 28</p> + +<p>Baculum: Stalk broad, greatest length (2.5 to 2.7 mm.) +1<sup>2</sup>/<sub>3</sub> times greatest breadth, 4 times greatest +depth; median process ossified, size small, <sup>1</sup>/<sub>5</sub> +length of stalk, higher than wide, having small anterodorsal prominence +in both specimens examined; lateral processes cartilaginous, relatively +small, displaced posteriorly, attenuate; posterior margin in dorsal view +broadly rounded, or having blunt median apex, convex throughout; basal +tuberosities moderately well developed, medially confluent, barely +visible in dorsal view when mature; in end-view median constriction +<sup>4</sup>/<sub>5</sub> greatest depth, ventral concavity deeper than +dorsal concavity, both comparatively shallow; stalk at mid-point +1½ times as wide as deep; shaft relatively slender, bowed dorsally +at tip, relatively straight otherwise; lateral profile in dorsal view a +gradual concave slope from point of greatest width anteriorly to distal +part of shaft.</p> + +<p><i>Specimens examined</i>: Two, from Douglas Co., Kansas, 76834 (2 mi. +N Baldwin), 68545 (1 mi. NE Pleasant Grove).</p> + + +<h3>Microtus (Pitymys) parvulus (Howell)</h3> +<p class="center">Fig. 40</p> + +<p>Baculum: Stalk broad, greatest length (2.4 mm. in specimen examined) +1¾ times greatest breadth, 4 times greatest depth; median process +ossified, size small, less than ¼ length of stalk, wider than +high, terminally flattened; lateral processes cartilaginous, relatively +small, attenuate; posterior margin in dorsal view flattened, irregularly +curved with concavities medially and laterally; basal tuberosities well +developed, medially confluent; visible in dorsal view; in end-view median +constriction <sup>2</sup>/<sub>3</sub> greatest depth, ventral concavity +well-formed, no dorsal concavity; stalk at mid-point twice as wide as +deep; shaft relatively slender, bowed dorsally toward tip; in dorsal view +lateral profile a gradual concave slope from point of greatest width +anteriorly to distal part of shaft; tip of shaft enlarged.</p> + +<p>The baculum of <i>M. parvulus</i> resembles that of <i>M. +pinetorum</i> more than it resembles the baculum of any other microtine +studied, differing primarily in smaller size.</p> + +<p><i>Specimen examined</i>: One, from 1 mi. W Micanopy, Alachua Co., +Florida, Univ. Florida No. 1508.</p> + + +<h3>Microtus (Pitymys) quasiater (Coues)</h3> +<p class="center">Figs. 29 and 30</p> + +<p>Baculum: Stalk broad, greatest length (2.6-3.2 mm.) +1<sup>1</sup>/<sub>3</sub> to 1<sup>2</sup>/<sub>3</sub> times greatest +breadth, 3<sup>1</sup>/<sub>3</sub> to 3<sup>2</sup>/<sub>3</sub> times +greatest depth; median process ossified, with ventral depression, process +¼ to <sup>1</sup>/<sub>3</sub> length of stalk, appressed to tip +of shaft, wider than high proximally, relatively broad terminally; +lateral processes cartilaginous, small, attenuate; posterior profile of +stalk in dorsal view broadly rounded, bilobate, or trilobate, median lobe +formed by posterior projection of dorsal shelf between enlarged lateral +tuberosities that form outer lobes, posterolateral faces of these +tuberosities visible in dorsal view of stalk; in end-view dorsal surface +slightly concave, ventral concavity broad and deep, median constriction + +<span class="pagenum"><a name="Page_209" id="Page_209">[Pg +209]</a></span> + +½ greatest depth; shaft flattened except tip that is more terete, +and bowed dorsally; at mid-point, stalk twice as wide as high; shaft +relatively slender terminally, narrower than median ossification.</p> + +<p>The baculum of <i>M. quasiater</i> is the largest and has the best +developed base and median process of the three American species of the +subgenus <i>Pitymys</i>. The three species closely resemble each other in +basic form.</p> + +<p><i>Specimens examined</i>: Five, all from Veracruz; Teocelo, 4500 ft., +30709, 30711; 4 km. N Tlapacoyán, 1700 ft., 24466; 5 km. N Jalapa, 4500 +ft., 19869, 19878.</p> + + +<h3>Microtus (Pitymys) fatioi (Mottaz)</h3> +<p class="center">Fig. 26</p> + +<p>The baculum of a single specimen (KU 67103) of <i>M. fatioi</i> from +Zermatt, Valais, Switzerland, was examined. The baculum is immature, as +evidenced by its small size, slender stalk and absence of ossified +processes, therefore no characterization is included.</p> + +<p>The baculum of another Old World species of the subgenus +<i>Pitymys</i>, <i>M. pyrenaicus</i> from France, figured and described +by Didier (1954:242-243), differs from all New World <i>Pitymys</i> +examined in processing ossified lateral processes.</p> + +<p>The status of <i>Pitymys</i>, as a genus or as a subgenus, is +uncertain. Hall and Cockrum (1953:448) considered the North American +<i>Pitymys</i> and <i>Pedomys</i> as subgenera of <i>Microtus</i>. They +did not state specifically the basis for this point of view, but mention +the fact that these two subgenera (<i>Pitymys</i> and <i>Pedomys</i>) +closely resemble each other cranially. These authors did not study nor +comment upon the status of the Old World <i>Pitymys</i>. It may be asked +whether the Old World and New World <i>Pitymys</i> have developed as +fossorial <i>Microtus</i> independently, or from an ancestor common to +both groups and not common to any other <i>Microtus</i>. Matthey +(1955:202) found 62 chromosomes (2N) in both the New World <i>Pitymys +pinetorum</i> and the Old World <i>Pitymys duodecimcostatus</i>. This +suggests, but does not prove, common ancestry.</p> + + +<h3>Neofiber alleni True</h3> +<p class="center">Fig. 49</p> + +<p>Baculum: Stalk massive, greatest length (4.7 mm.) 1¾ times +greatest breadth, 4 times greatest depth; ossification in digitate +processes variable; in one (KU 27123) of two specimens examined lateral +processes ossified and median process unossified, as in two specimens +examined by Hamilton (1946:379) from "southern Florida"; in my other +specimen (KU 27268) that is possibly more mature, median process ossified +although less deeply stained than lateral ossifications or stalk; +posterior profile in probable dorsal view roughly rounded; in end-view +probable dorsal concavity deep, ventral concavity broad but shallow, and +with center convex; median constriction <sup>3</sup>/<sub>5</sub> +greatest depth; shaft heavy, least depth <sup>2</sup>/<sub>3</sub> +greatest depth of base; stalk, at mid-point, slightly wider than deep and +more than <sup>1</sup>/<sub>3</sub> width of base; lateral profile in +dorsal view sharply incurved distal to point of greatest breadth, shaft +therefore relatively distinct from basal part of stalk; slight +subterminal constriction; tip less reduced in the two specimens examined +than in two figured by Hamilton. In preparation, the tissues that make it +possible to distinguish + +<span class="pagenum"><a name="Page_210" id="Page_210">[Pg +210]</a></span> + +with certainty the dorsal and ventral surfaces of the baculum were +removed in both specimens.</p> + +<p><i>Specimens examined</i>: Two, of the subspecies <i>Neofiber alleni +alleni</i>, 2 mi. S Gainesville, Alachua Co., Florida, 27268; 1 mi. E +Courtenay, Merritt Island, Brevard Co., Florida, 27123.</p> + + +<h3>Lagurus curtatus (Cope)</h3> +<p class="center">Fig. 46</p> + +<p>Baculum: Stalk slender, greatest length (2.5 mm.) 2 to +2<sup>2</sup>/<sub>3</sub> times greatest breadth, 4 to 5 times greatest +depth; three ossified processes; median one more than +<sup>1</sup>/<sub>3</sub> length of stalk, curved dorsally toward tip, +proximally flattened and having acute lateral angles in dorsal view, +wider than deep except in distal half; lateral processes smaller than +median one, slenderer, shorter, of approximately same depth, also curved +dorsally; base of stalk well developed, basal tuberosities medially +confluent, in part visible in dorsal view, in end-view wider ventrally +than dorsally, dorsal and ventral concavities of equal depth and both +wide, medial constriction ½ greatest depth; posterior profile in +dorsal view broadly bilobate; lateral profile with abrupt transition from +basal tuberosities to gradually converging, slightly curved sides of +shaft; shaft terminally inflated.</p> + +<p>Dearden (1958:543) described and figured the bacula of six subspecies +of <i>Lagurus curtatus</i> and two Asiatic species, <i>Lagurus +lagurus</i> and <i>Lagurus luteus</i>. He examined at least 34 specimens +of <i>L. curtatus</i> and found geographic variation in size, breadth of +shaft distally, and proportions of digital ossifications to each other +and to the stalk. The description that I have given above pertains to +<i>L. c. levidensis</i>.</p> + +<p>The baculum of the Asiatic <i>Lagurus (Lagurus) lagurus</i> figured by +Ognev (1950:554) agrees with that of <i>Lagurus (Lemmiscus) curtatus</i>, +described here, in the relatively elongate shaft and slender stalk, the +proportions of the processes, and the well-formed and moderately enlarged +base of the stalk. The bacula of three <i>Lagurus lagurus</i> examined by +Dearden (1958:545) were of older individuals than the specimen that Ognev +figures and differ from it and from bacula of <i>Lagurus curtatus</i> +(all subspecies) in the unusual, almost heart shaped, median process, and +in larger size. <i>Lagurus luteus</i> examined by Dearden (1958:545) +differs from both <i>Lagurus lagurus</i> and <i>Lagurus curtatus</i> in +lacking lateral digital ossifications and in having shorter median +digital ossifications and wider base of stalk.</p> + +<p><i>Specimens examined</i>: Seven <i>Lagurus curtatus levidensis</i> +from Wyoming; 9 mi. S Robertson, Uinta Co., 26045, 26053; 8 mi. S, +2½ mi. E Robertson, Uinta Co., 26049; Farson, Sweetwater Co., +37906; 16 mi. S, 11 mi. W Waltman, Natrona Co., 42457; 32 mi. S, 22 mi. E +Rock Springs, 42465, 42466.</p> + +<p style="margin-bottom:2em;">The following key to the bacula in some adult North American +Microtinae is intended to help point out some of the most important +differences. It should be noted that not all species can be keyed out on +the basis of the baculum. The most difficult group in this respect +includes the species of <i>Microtus</i> that have small or no ossified +lateral processes, especially species of the subgenera <i>Pedomys</i> and +<i>Pitymys</i>, and the two species <i>Microtus californicus</i> and +<i>Microtus mexicanus</i> of the subgenus <i>Microtus</i>. Another +complicating factor is the variability of bacula evident in some species +even in the small samples available. + +<span class="pagenum"><a name="Page_211" id="Page_211">[Pg +211]</a></span> + +It is to be expected that additional specimens will show variations not +yet observed.</p> + +<h2 class="smcap">Key to the Bacula of Some North American Microtines</h2> + + +<table class="key"> + <tr> + <td class="text">1. Length of lateral digital ossifications more than <sup>1</sup>/<sub>3</sub> breadth of stalk</td> + <td class="number">2</td> + </tr> + <tr> + <td class="text">1´. Length of lateral digital ossifications less than <sup>1</sup>/<sub>3</sub> breadth of stalk or absent</td> + <td class="number">15</td> + </tr> + <tr> + <td class="text">2. Size small (total length of baculum less than 5.5 mm.)</td> + <td class="number">3</td> + </tr> + <tr> + <td class="text">2´. Size large (total length of baculum more than 5.5 mm.)</td> + <td class="number">14</td> + </tr> + <tr> + <td class="text">3. Width at mid-point of stalk more than <sup>1</sup>/<sub>3</sub> greatest breadth of stalk</td> + <td class="number">4</td> + </tr> + <tr> + <td class="text">2´. Size large (total length of baculum more than 5.5 mm.)</td> + <td class="number">14</td> + </tr> + <tr> + <td class="text">3´. Width at mid-point of stalk less than <sup>1</sup>/<sub>3</sub> greatest breadth of stalk,</td> + <td class="number">8</td> + </tr> + <tr> + <td class="text">4. Stalk, viewed from proximal end hour-glass shaped, and width + of stalk less than ½ length of stalk.... <i>Phenacomys + intermedius</i>,</td> + <td class="number"><a href="#Page_197">p. 197</a></td> + </tr> + <tr> + <td class="text">4´. Stalk not both hour-glass shaped when viewed from proximal + end, and with width less than ½ length of stalk</td> + <td class="number">5</td> + </tr> + <tr> + <td class="text">5. Shaft thin basally, thickness less than <sup>1</sup>/<sub>3</sub> of greatest breadth</td> + <td class="number">6</td> + </tr> + <tr> + <td class="text">5´. Shaft thick basally, thickness <sup>1</sup>/<sub>3</sub> or more of greatest breadth</td> + <td class="number">7</td> + </tr> + <tr> + <td class="text">6. Stalk more or less straight, base not deflected. <i>Microtus + oeconomus</i>,</td> + <td class="number"><a href="#Page_204">p. 204</a></td> + </tr> + <tr> + <td class="text">6´. Stalk spatulate, and base deflected from axis of shaft.... + <i>Microtus guatemalensis</i>,</td> + <td class="number"><a href="#Page_198">p. 198</a></td> + </tr> + <tr> + <td class="text">7. Base enlarged, depth nearly ½ of breadth.... <i>Lemmus + trimucronatus</i>,</td> + <td class="number"><a href="#Page_193">p. 193</a></td> + </tr> + <tr> + <td class="text">7´. Base moderately enlarged, depth near <sup>1</sup>/<sub>3</sub> of breadth.... + <i>Microtus pennsylvanicus</i>, <a href="#Page_206">p. 206</a>, or <i>Microtus townsendii</i>,</td> + <td class="number"><a href="#Page_204">p. 204</a></td> + </tr> + <tr> + <td class="text">8. Base hour-glass shaped as viewed from proximal end.... + <i>Phenacomys intermedius</i>,</td> + <td class="number"><a href="#Page_197">p. 197</a></td> + </tr> + <tr> + <td class="text">8´. Not so</td> + <td class="number">9</td> + </tr> + <tr> + <td class="text">9. Lateral processes separated from tip of shaft by more than the + thickness of the lateral process</td> + <td class="number">10</td> + </tr> + <tr> + <td class="text">9´. Lateral processes separated from tip of shaft by less than the + thickness of the lateral process</td> + <td class="number">11</td> + </tr> + <tr> + <td class="text">10. Lateral processes more than ½ the width of median + process.... <i>Microtus longicaudus</i>,</td> + <td class="number"><a href="#Page_201">p. 201</a></td> + </tr> + <tr> + <td class="text">10´. Lateral processes slender, less than ½ the width of median + process.... <i>Microtus montanus</i>,</td> + <td class="number"><a href="#Page_204">p. 204</a></td> + </tr> + <tr> + <td class="text">11. Lateral ossifications equal in length to median + ossification.... <i>Clethrionomys</i>,</td> + <td class="number"><a href="#Page_194">p. 194</a></td> + </tr> + <tr> + <td class="text">11´. Lateral ossifications shorter than median ossification</td> + <td class="number">12</td> + </tr> + <tr> + <td class="text">12. Size small, less than 3.4 mm. in total length.... + <i>Microtus oregoni</i>,</td> + <td class="number"><a href="#Page_199">p. 199</a></td> + </tr> + <tr> + <td class="text">12´. Size medium, more than 3.4 mm. in total length</td> + <td class="number">13</td> + </tr> + <tr> + <td class="text">13. Greatest width of stalk at a point about <sup>1</sup>/<sub>3</sub> of length of + stalk from base.... <i>Microtus chrotorrhinus</i> (Hamilton, 1946:382).</td> + <td class="number"> </td> + </tr> + <tr> + <td class="text">13´. Greatest width of stalk at a point less than <sup>1</sup>/<sub>3</sub> of length of + stalk from base.... <i>Lagurus curtatus</i>,</td> + <td class="number"><a href="#Page_210">p. 210</a></td> + </tr> + <tr> + <td class="text">14. Size of baculum larger, base more than 3 mm. wide, processes + all well developed.... <i>Ondatra zibethicus</i>,</td> + <td class="number"><a href="#Page_198">p. 198</a></td> + </tr> + <tr> + <td class="text">14´. Size of baculum smaller, base less than 3 mm. wide, processes + poorly developed in some animals.... <i>Neofiber alleni</i>,</td> + <td class="number"><a href="#Page_209">p. 209</a></td> + </tr> + <tr> + <td class="text">15. At least one digital ossification present</td> + <td class="number">16</td> + </tr> + <tr> + <td class="text"> + <span class="pagenum"><a name="Page_212" id="Page_212">[Pg + 212]</a></span> + 15´. Digital ossifications not present.... <i>Dicrostonyx groenlandicus</i>,</td> + <td class="number"><a href="#Page_193">p. 193</a></td> + </tr> + <tr> + <td class="text">16. Breadth of stalk at least ½ length of stalk</td> + <td class="number">17</td> + </tr> + <tr> + <td class="text">16´. Breadth of stalk less than ½ length of stalk</td> + <td class="number">19</td> + </tr> + <tr> + <td class="text">17. Length of stalk greater than 3.6 mm. and less than 1½ + times its greatest breadth.... <i>Microtus richardsoni</i>,</td> + <td class="number"><a href="#Page_199">p. 199</a></td> + </tr> + <tr> + <td class="text">17´. Length of stalk usually less than 3.6 mm., or if more than + 3.6 mm. (up to 4.0 mm.) then length 1½ times or more its + greatest breadth</td> + <td class="number">18</td> + </tr> + <tr> + <td class="text">18. Median process attenuate distally in dorsal view, and + relatively long (more than twice its own breadth), <sup>1</sup>/<sub>5</sub> to <sup>3</sup>/<sub>5</sub> the + length of stalk; breadth of stalk usually <sup>2</sup>/<sub>3</sub> or more length of + stalk.... <i>Microtus miurus</i>,</td> + <td class="number"><a href="#Page_200">p. 200</a></td> + </tr> + <tr> + <td class="text">18´. Median process relatively blunt distally in dorsal view, + relatively short (usually less than ¼ length of stalk), breadth + of stalk usually less than <sup>2</sup>/<sub>3</sub> length of stalk.... + <i>Pitymys</i>, <a href="#Page_208">p. 208</a>, <i>Pedomys</i>, <a href="#Page_207">p. 207</a>, or <i>Microtus mexicanus</i>,</td> + <td class="number"><a href="#Page_205">p. 205</a></td> + </tr> + <tr> + <td class="text">19. Distal processes small and firmly ankylosed to distal end of + shaft.... <i>Phenacomys longicaudus</i>,</td> + <td class="number"><a href="#Page_197">p. 197</a></td> + </tr> + <tr> + <td class="text">19´. Distal processes if present not firmly ankylosed to distal + end of shaft</td> + <td class="number">20</td> + </tr> + <tr> + <td class="text">20. Dorsal concavity of base as viewed from proximal end usually + deeper than ventral concavity.... <i>Microtus mexicanus</i>,</td> + <td class="number"><a href="#Page_205">p. 205</a></td> + </tr> + <tr> + <td class="text">20´. Dorsal and ventral concavities of base equal in depth or + ventral one the deeper</td> + <td class="number">21</td> + </tr> + <tr> + <td class="text">21. Total length of baculum more than 3.6 mm.... <i>Microtus + californicus</i>,</td> + <td class="number"><a href="#Page_205">p. 205</a></td> + </tr> + <tr> + <td class="text">21´. Total length of baculum less than 3.6 mm.... <i>Synaptomys + cooperi</i>,</td> + <td class="number"><a href="#Page_194">p. 194</a></td> + </tr> +</table> + + +<h2>DISCUSSION</h2> + +<p>Owing to shortness of lower incisors and present geographic +distribution of the species, Hinton (1926:35) considered the Tribe Lemmi +(lemmings) to be more primitive than the Tribe Microti (voles). The +surviving lemmings are specialized in many features and therefore are +considered as advanced end-products of an evolutionary radiation of a +primitive microtine stock, of which all earlier stages are extinct.</p> + +<p>Hinton regarded <i>Dicrostonyx</i> as the most primitive of the genera +of lemmings on account of its more complex molar teeth (complexity was +considered to be primitive), and on account of the presence of three +primitive longitudinal rows of tubercles in unworn molars. The other +three genera were arranged in order of increasing specialization as +follows: <i>Synaptomys</i>, <i>Myopus</i>, <i>Lemmus</i>.</p> + +<p>If the baculum tended to retain its primitive character while +specializations in the external anatomy developed, and if the above +arrangement is correct the most primitive bacula would be found +in <i>Dicrostonyx</i> and in <i>Synaptomys</i>. The baculum in these two +genera in comparison to that in <i>Myopus</i> (as figured by Ognev, 1948:512) + +<span class="pagenum"><a name="Page_213" id="Page_213">[Pg 213]</a></span> + +and <i>Lemmus</i> has a slenderer stalk and smaller digital ossifications +or none at all. The baculum in the genera of lemmings increases in +robustness and the development of processes from <i>Dicrostonyx</i>, to +<i>Synaptomys</i>, to <i>Myopus</i>, to <i>Lemmus</i>—the same +order outlined above for total of specialization. The two extremes in +this series are near the extremes of variation in bacula to be found in +all microtines. The baculum in lemmings as a group cannot then be +considered more primitive than in voles as a group, although the voles +are usually considered to be more advanced. The situation in the voles, +as we shall see, casts a different light on the matter.</p> + +<p>The voles, Tribe Microti, were considered by Hinton (1926:40) to be +more advanced than the lemmings because the incisors of the voles are +longer and the root of their last lower molar is lingual to the root of +the incisor. Hinton thought also that the murine ancestors of microtines +had shorter incisors and that the backward extension of the incisors in +the voles is a more ancient feature than the hypsodonty of the molars. A +trend in the molar teeth has been toward greater hypsodonty. The voles in +which the molars are least hypsodont are thus considered primitive. These +include the living genera <i>Clethrionomys</i>, <i>Phenacomys</i>, +<i>Ondatra</i>, <i>Dolomys</i>, <i>Ellobius</i>, and <i>Prometheomys</i>. +Therefore, the baculum, in these assumedly primitive genera, would be +expected to resemble the baculum in the lemmings or at least the most +primitive lemmings. This is not the case.</p> + +<p>The bacula that I have examined of <i>Clethrionomys</i> and +<i>Phenacomys</i> have well-developed digital ossifications. In this they +resemble the baculum of the genus <i>Lemmus</i>, the most advanced genus +of lemmings according to Hinton. The baculum of <i>Dolomys</i> has not +been studied. The baculum in <i>Ondatra</i>, and in <i>Prometheomys</i> +as illustrated by Ognev (1948:552), also possesses well-developed +processes. The baculum of <i>Ellobius</i> is small and lacks processes +(as figured by Ognev, 1950:662). No ossification was found in a single +specimen of <i>Ellobius</i> examined by me although the entire glans +penis was removed and cleared without dissection. So far as known then, +with the exception of <i>Ellobius</i> and <i>Phenacomys longicaudus</i> +(Dearden, 1958:547), the primitive microtines having rooted molars +possess bacula having three well-developed ossified processes.</p> + +<p>Voles of the genus <i>Microtus</i> vary in the structure of the +baculum almost as much as do the lemmings. Within the single subgenus +<i>Microtus</i> some individuals of <i>Microtus mexicanus</i>, for +example, have minute ossified lateral processes and other individuals +lack these + +<span class="pagenum"><a name="Page_214" id="Page_214">[Pg 214]</a></span> + +processes; <i>Microtus pennsylvanicus</i> and some other species have +proportionately large lateral ossifications. If the well-developed +condition of the baculum in the microtines having rooted molars is +primitive, then within the genus <i>Microtus</i> those species having +well-developed bacula may be considered primitive.</p> + +<p>The genera <i>Lagurus</i> and <i>Neofiber</i> have moderately +developed or well-developed lateral processes. <i>Neofiber</i> exhibits a +tendency, not prominent elsewhere, to have a proportionately smaller +median process rather than reduced lateral processes.</p> + +<p>American species of <i>Microtus</i> (genus and subgenus) that have +moderately- to well-developed ossified lateral processes are <i>M. +townsendii</i>, <i>M. oeconomus</i>, <i>M. pennsylvanicus</i>, <i>M. +montanus</i>, and <i>M. chrotorrhinus</i>. <i>Microtus</i> of other +subgenera having this type of baculum include <i>M. (Herpetomys) +guatemalensis</i>, <i>M. (Chilotus) oregoni</i>, and <i>M. (Chionomys) +longicaudus</i>.</p> + +<p>American species of <i>Microtus</i> (genus and subgenus) in which the +lateral ossifications are weakly developed or absent (although +cartilaginous lateral processes are present) include <i>M. mexicanus</i> +and <i>M. californicus</i>. In other subgenera, species of +<i>Microtus</i> having reduced lateral ossifications are <i>M. (Pedomys) +ochrogaster</i>, <i>M. (Pitymys) pinetorum</i>, <i>M. (Pitymys) +parvulus</i>, <i>M. (Pitymys) quasiater</i>, <i>M. (Arvicola) +richardsoni</i>, and <i>M. (Stenocranius) miurus</i>.</p> + +<p>The microtines are essentially holarctic in distribution. Both of the +tribes, the lemmings and the voles, as well as primitive representatives +of each tribe (not considering <i>Ellobius</i>) occur in both the Old +World and New World. It is not certain on which continent (or continents) +the Microtinae first differentiated. It is certain, however, that at +various times, both early and late in the evolution of the subfamily, +representatives have crossed from Eurasia to North America or <i>vice +versa</i>. Each of 10 or more microtines in the New World is more closely +related to some microtine in the Old World than to any other microtine in +the New World.</p> + +<p>The similarities or differences in the baculum in Old World and New +World representatives placed in the same genus or subgenus, or thought to +be "companion species" have been commented upon in accounts of +<i>Lemmus</i>, <i>Dicrostonyx</i>, <i>Clethrionomys</i>, <i>Lagurus</i>, +<i>Arvicola</i>, <i>Stenocranius</i>, <i>Chilotus</i>, <i>Chionomys</i>, +<i>Pitymys</i>, and in accounts of <i>Microtus agrestis</i> as compared +with <i>M. pennsylvanicus</i>, and <i>Microtus oeconomus</i> (both Old +World and New World).</p> + +<p>The baculum in the Microtinae more closely resembles the baculum in +the Cricetinae of the Old World than in the Murinae, or than in any other +rodents known to me. This resemblance suggests relationship between +Microtinae and Cricetinae.</p> + + +<p><span class="pagenum"><a name="Page_215" id="Page_215">[Pg 215]</a></span></p> + +<h2>LITERATURE CITED</h2> + +<table> + <tr> + <td colspan="2" class="smcap">Argyropulo, A. I.</td> + </tr> + <tr> + <td class="litcit_num">1933a.</td> + <td class="litcit_txt">Die Gattungen und Arten der Hamster (<i>Cricetinae</i> Murray, 1866) der Paläarktik. Zeitschr. f. +Säugetierkunde, 8:129-149, 27 figs. in text.</td> + </tr> + <tr> + <td class="litcit_num">1933b.</td> + <td class="litcit_txt">über zwei neue paläarktische Wühlmäuse. Zeitschr. f. Säugetierkunde, 8:180-183, 3 figs. in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Callery, R.</td> + </tr> + <tr> + <td class="litcit_num">1951.</td> + <td class="litcit_txt">Development of the os genitale in the golden hamster, <i>Mesocricetus (Cricetus) auratus</i>. Jour. Mamm., +32:204-207, 1 fig. in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Chamberlain, J. L.</td> + </tr> + <tr> + <td class="litcit_num">1954.</td> + <td class="litcit_txt">The Block Island meadow mouse, <i>Microtus provectus</i>. Jour. Mamm., 35:587-589, 2 tables in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Dearden, L. C.</td> + </tr> + <tr> + <td class="litcit_num">1958.</td> + <td class="litcit_txt">The baculum in <i>Lagurus</i> and related microtines. Jour. Mamm., 39:541-553, 1 fig. in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Didier, R.</td> + </tr> + <tr> + <td class="litcit_num">1943.</td> + <td class="litcit_txt">L'os pénien des Campagnols de France du Genre <i>Arvicola</i>. Mammalia, 7:74-79, 10 figs. in text.</td> + </tr> + <tr> + <td class="litcit_num">1954.</td> + <td class="litcit_txt">Etude systématique de l'os pénien des Mammifères (suite), Rongeurs: Muridés. Mammalia, 18:237-256, 14 figs. in +text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Ellerman, J. R.</td> + </tr> + <tr> + <td class="litcit_num">1941.</td> + <td class="litcit_txt">The families and genera of living rodents. Vol. II. Family Muridae. The British Museum (Natural History), London, +pp. xii + 690, 50 figs.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Friley, Charles E.</td> + </tr> + <tr> + <td class="litcit_num">1947.</td> + <td class="litcit_txt">Preparation and preservation of the baculum of mammals. Jour. Mamm., 28:395-397, 1 fig. in text.</td> + </tr> + <tr> + <td colspan="2"><span class="smcap">Hall, E. R.</span>, and <span class="smcap">E. L. Cockrum.</span></td> + </tr> + <tr> + <td class="litcit_num">1953.</td> + <td class="litcit_txt">A synopsis of the North American microtine rodents. Univ. Kansas Publ., Mus. Nat. Hist., 5:373-498, 149 figs. in +text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Hamilton, W. J., Jr.</td> + </tr> + <tr> + <td class="litcit_num">1946.</td> + <td class="litcit_txt">A study of the baculum in some North American Microtinae. Jour. Mamm., 27:378-387, 3 figs. in text.</td> + </tr> + <tr> + <td colspan="2"><span class="smcap">Hibbard, C. W.</span>, and <span class="smcap">G. C. Rinker.</span></td> + </tr> + <tr> + <td class="litcit_num">1942.</td> + <td class="litcit_txt">A new bog-lemming (Synaptomys) from Meade County, Kansas. Univ. Kansas Sci. Bull., 28:25-35, 3 figs. in text.</td> + </tr> + <tr> + <td class="litcit_num">1943.</td> + <td class="litcit_txt">A new meadow mouse (<i>Microtus ochrogaster taylori</i>) from Meade County, Kansas. Univ. Kansas Sci. +Bull., 29:255-268, 5 figs. in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Hinton, M. A. C.</td> + </tr> + <tr> + <td class="litcit_num">1926.</td> + <td class="litcit_txt">Monograph of the voles and lemmings (Microtinae), living and extinct, Vol. I. British Museum (Natural +History), London, pp. xvi + 488, plus 15 plates, 110 figs. in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Matthey, R.</td> + </tr> + <tr> + <td class="litcit_num">1953.</td> + <td class="litcit_txt">Les Chromosomes des Muridae. Revue Suisse de Zoologie, 60:225-283, avec les planches 1 à 4 groupant 84 +photomicrographies, 98 figures et 5 schemas dans le texte.</td> + </tr> + <tr> + <td class="litcit_num">1955. + <span class="pagenum"><a name="Page_216" id="Page_216">[Pg 216]</a></span></td> + <td class="litcit_txt"> Nouveaux documents sur les chromosomes des Muridae. Problèmes de cytologie comparée et de taxonomie chez les +Microtinae. Revue Suisse de Zoologie, 62:163-206, avec 114 figures.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Miller, G. S.</td> + </tr> + <tr> + <td class="litcit_num">1896.</td> + <td class="litcit_txt">Genera and subgenera of voles and lemmings. North American Fauna No. 12, pp. 1-85, 40 figs. and 3 plates in +text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Ognev, S. I.</td> + </tr> + <tr> + <td class="litcit_num">1948.</td> + <td class="litcit_txt">The mammals of Russia (USSR) and adjacent countries (The mammals of Eastern Europe and Northern Asia), Vol. 6. +Publ. Acad. Sci. USSR, pp. 1-587, 260 figs., 12 maps, and 11 color plates +in text (in Russian).</td> + </tr> + <tr> + <td class="litcit_num">1950.</td> + <td class="litcit_txt">The mammals of Russia (USSR) and adjacent countries (The mammals of Eastern Europe and Northern Asia), Vol. 7. +Publ. Acad. Sci. USSR, pp. 1-736, 347 figs., 15 maps, and 10 color plates +in text (in Russian).</td> + </tr> + <tr> + <td colspan="2" class="smcap">Ruth, E. B.</td> + </tr> + <tr> + <td class="litcit_num">1934.</td> + <td class="litcit_txt">The os priapi: A study in bone development. Anat. Rec., 60:231-249, 16 figs. in 3 plates.</td> + </tr> + <tr> + <td colspan="2"><span class="smcap">Smith, D. A.</span>, and <span class="smcap">J. B. Foster.</span></td> + </tr> + <tr> + <td class="litcit_num">1957.</td> + <td class="litcit_txt">Notes on the small mammals of Churchill, Manitoba. Jour. Mamm., 38:98-115, 3 figs. and 3 tables in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Wheeler, B.</td> + </tr> + <tr> + <td class="litcit_num">1956.</td> + <td class="litcit_txt">Comparison of the Block Island "species" of <i>Microtus</i> with <i>M. pennsylvanicus</i>. Evolution, 10:176-186, +4 figs. and 2 tables in text.</td> + </tr> + <tr> + <td colspan="2" class="smcap">White, J. A.</td> + </tr> + <tr> + <td class="litcit_num">1951.</td> + <td class="litcit_txt">A practical method for mounting the bacula of small mammals. Jour. Mamm., 32:125.</td> + </tr> + <tr> + <td colspan="2" class="smcap">Zimmerman, K.</td> + </tr> + <tr> + <td class="litcit_num">1955.</td> + <td class="litcit_txt">Die Gattung <i>Arvicola</i> Lac. im System der Microtinae. Säugetierkundliche Mitteilungen, 3:110-112, 2 figs. in +text.</td> + </tr> + <tr> + <td colspan="2"><i>Transmitted August 14, 1959.</i></td> + </tr> +</table> + +<p class="center">28-774</p> + +<hr /> + + +<p><span class="pagenum"><a name="front_flap" id="front_flap">[Front Cover Inside]</a></span></p> + +<h2>UNIVERSITY OF KANSAS PUBLICATIONS<br /> +MUSEUM OF NATURAL HISTORY</h2> + +<p>Institutional libraries interested in publications exchange may obtain +this series by addressing the Exchange Librarian, University of Kansas +Library, Lawrence, Kansas. Copies for individuals, persons working in a +particular field of study, may be obtained by addressing instead the +Museum of Natural History, University of Kansas, Lawrence, Kansas. There +is no provision for sale of this series by the University Library which +meets institutional requests, or by the Museum of Natural History which +meets the requests of individuals. However, when individuals request +copies from the Museum, 25 cents should be included, for each separate +number that is 100 pages or more in length, for the purpose of defraying +the costs of wrapping and mailing.</p> + +<p>* An asterisk designates those numbers of which the Museum's supply +(not the Library's supply) is exhausted. Numbers published to date, in +this series, are as follows:</p> + + <dl> + <dt>Vol. 1.</dt> + <dd>Nos. 1-26 and index. Pp. 1-638, 1946-1950.</dd> + + <dt>*Vol. 2.</dt> + <dd>(Complete) Mammals of Washington. By Walter W. Dalquest. Pp. 1-444, 140 figures in text. April 9, 1948.</dd> + + <dt>Vol. 3.</dt> + <dd class="small_margin"><ol class="start_1"> + <li>*The avifauna of Micronesia, its origin, evolution, and distribution. By Rollin + H. Baker. Pp. 1-359, 16 figures in text. June 12, 1951.</li> + <li>*A quantitative study of the nocturnal migration of birds. By George H. + Lowery, Jr. Pp. 361-472, 47 figures in text. June 29, 1951.</li> + <li>Phylogeny of the waxwings and allied birds. By M. Dale Arvey. Pp. 473-530, + 49 figures in text, 13 tables. October 10, 1951.</li> + <li>Birds from the state of Veracruz, Mexico. By George H. Lowery, Jr., and + Walter W. Dalquest. Pp. 531-649, 7 figures in text, 2 tables. October 10, + 1951.</li> + </ol></dd> + <dd>Index. Pp. 651-681.</dd> + <dt>*Vol. 4.</dt> + <dd>(Complete) American weasels. By E. Raymond Hall. Pp. 1-466, 41 plates, 31 + figures in text. December 27, 1951.</dd> + <dt>Vol. 5.</dt> + <dd>Nos. 1-37 and index. Pp. 1-676, 1951-1953.</dd> + <dt>*Vol. 6.</dt> + <dd>(Complete) Mammals of Utah, <i>taxonomy</i> and <i>distribution</i>. By Stephen D. + Durrant. Pp. 1-549, 91 figures in text, 30 tables. August 10, 1952.</dd> + <dt>Vol. 7.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>*Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73 figures in text, + 37 tables. August 25, 1952.</li> + + <li>Ecology of the opossum on a natural area in northeastern Kansas. By Henry + S. Fitch and Lewis L. Sandidge. Pp. 305-338, 5 figures in text. August + 24, 1953.</li> + <li>The silky pocket mice (Perognathus flavus) of Mexico. By Rollin H. Baker. + Pp. 339-347, 1 figure in text. February 15, 1954.</li> + <li>North American jumping mice (Genus Zapus). By Phillip H. Krutzsch. Pp. + 349-472, 47 figures in text, 4 tables. April 21, 1954.</li> + <li>Mammals from Southeastern Alaska. By Rollin H. Baker and James S. + Findley. Pp. 473-477. April 21, 1954.</li> + <li>Distribution of Some Nebraskan Mammals. By J. Knox Jones, Jr. Pp. 479-487. + April 21, 1954.</li> + <li>Subspeciation in the montane meadow mouse, Microtus montanus, in Wyoming + and Colorado. By Sydney Anderson. Pp. 489-506, 2 figures in text. + July 23, 1954.</li> + <li>A new subspecies of bat (Myotis velifer) from southeastern California and + Arizona. By Terry A. Vaughan. Pp. 507-512. July 23, 1954.</li> + <li>Mammals of the San Gabriel mountains of California. By Terry A. Vaughan. + Pp. 513-582, 1 figure in text, 12 tables. November 15, 1954.</li> + <li>A new bat (Genus Pipistrellus) from northeastern Mexico. By Rollin H. + Baker. Pp. 583-586. November 15, 1954.</li> + <li>A new subspecies of pocket mouse from Kansas. By E. Raymond Hall. Pp. + 587-590. November 15, 1954.</li> + <li>Geographic variation in the pocket gopher, Cratogeomys castanops, in Coahuila, + Mexico. By Robert J. Russell and Rollin H. Baker. Pp. 591-608. + March 15, 1955.</li> + <li>A new cottontail (Sylvilagus floridanus) from northeastern Mexico. By Rollin + H. Baker. Pp. 609-612. April 8, 1955.</li> + <li>Taxonomy and distribution of some American shrews. By James S. Findley. + Pp. 613-618. June 10, 1955.</li> + <li>The pigmy woodrat, Neotoma goldmani, its distribution and systematic position. + By Dennis G. Rainey and Rollin H. Baker. Pp. 619-624, 2 figures in + text. June 10, 1955.</li> + </ol></dd> + <dd>Index. Pp. 625-651.</dd> + <dt><span class="pagenum"><a name="back_flap" id="back_flap">[Back Cover Inside]</a></span> + Vol. 8.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>Life history and ecology of the five-lined skink, Eumeces fasciatus. +By Henry S. Fitch. Pp. 1-156, 26 figures in text. September 1, 1954.</li> +<li>Myology and serology of the Avian Family Fringillidae, a taxonomic +study. By William B. Stallcup. Pp. 157-211, 23 figures in text, 4 tables. +November 15, 1954.</li> + + <li>An ecological study of the collared lizard (Crotaphytus collaris). +By Henry S. Fitch. Pp. 213-274, 10 figures in text. February 10, +1956.</li> + + <li>A field study of the Kansas ant-eating frog, Gastrophryne olivacea. +By Henry S. Fitch. Pp. 275-306, 9 figures in text. February 10, +1956.</li> + + <li>Check-list of the birds of Kansas. By Harrison B. Tordoff. Pp. +307-359, 1 figure in text. March 10, 1956.</li> + + <li>A population study of the prairie vole (Microtus ochrogaster) in +northeastern Kansas. By Edwin P. Martin. Pp. 361-416, 19 figures in text. +April 2, 1956.</li> + + <li>Temperature responses in free-living amphibians and reptiles of +northeastern Kansas. By Henry S. Fitch. Pp. 417-476, 10 figures in text, +6 tables. June 1, 1956.</li> + + <li>Food of the crow, Corvus brachyrhynchos Brehm, in south-central +Kansas. By Dwight Platt. Pp. 477-498, 4 tables. June 8, 1956.</li> + + <li>Ecological observations on the woodrat Neotoma floridana. By Henry +S. Fitch and Dennis G. Rainey. Pp. 499-533, 3 figures in text. June 12, +1956.</li> + + <li>Eastern woodrat, Neotoma floridana; Life history and ecology. By +Dennis G. Rainey. Pp. 535-646, 12 plates, 13 figures in text. August 15, +1956.</li> + </ol></dd> + <dd>Index. Pp. 647-675.</dd> + <dt>Vol. 9.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>Speciation of the wandering shrew. By James S. Findley. Pp. 1-68, 18 +figures in text. December 10, 1955.</li> + + <li>Additional records and extension of ranges of mammals from Utah. By +Stephen D. Durrant, M. Raymond Lee, and Richard M. Hansen. Pp. 69-80. +December 10, 1955.</li> + + <li>A new long-eared myotis (Myotis evotis) from northeastern Mexico. By +Rollin H. Baker and Howard J. Stains. Pp. 81-84. December 10, 1955.</li> + + <li>Subspeciation in the meadow mouse, Microtus pennsylvanicus, in +Wyoming. By Sydney Anderson. Pp. 85-104, 2 figures in text. May 10, +1956.</li> + + <li>The condylarth genus Ellipsodon. By Robert W. Wilson. Pp. 105-116, 6 +figures in text. May 19, 1956.</li> + + <li>Additional remains of the multituberculate genus Eucosmodon. By +Robert W. Wilson. Pp. 117-123, 10 figures in text. May 19, 1956.</li> + + <li>Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp. 125-335, 75 +figures in text. June 15, 1956.</li> + + <li>Comments on the taxonomic status of Apodemus peninsulae, with +description of a new subspecies from North China. By J. Knox Jones, Jr. +Pp. 337-346, 1 figure in text, 1 table. August 15, 1956.</li> + + <li>Extensions of known ranges of Mexican bats. By Sydney Anderson. Pp. +347-351. August 15, 1956.</li> + + <li>A new bat (Genus Leptonycteris) from Coahuila. By Howard J. Stains. +Pp. 353-356. January 21, 1957.</li> + + <li>A new species of pocket gopher (Genus Pappogeomys) from Jalisco, +Mexico. By Robert J. Russell. Pp. 357-361. January 21, 1957.</li> + + <li>Geographic variation in the pocket gopher, Thomomys bottae, in +Colorado. By Phillip M. Youngman. Pp. 363-387, 7 figures in text. +February 21, 1958.</li> + + <li>New bog lemming (genus Synaptomys) from Nebraska. By J. Knox Jones, +Jr. Pp. 385-388. May 12, 1958.</li> + + <li>Pleistocene bats from San Josecito Cave, Nuevo León, México. By J. +Knox Jones, Jr. Pp. 389-396. December 19, 1958.</li> + + <li>New subspecies of the rodent Baiomys from Central America. By Robert +L. Packard. Pp. 397-404. December 19, 1958.</li> + + <li>Mammals of the Grand Mesa, Colorado. By Sydney Anderson. Pp. +405-414, 1 figure in text, May 20, 1959.</li> + + <li>Distribution, variation, and relationships of the montane vole, +Microtus montanus. By Sydney Anderson. Pp. 415-511, 12 figures in text, 2 +tables. August 1, 1959.</li> + + <li>Conspecificity of two pocket mice, Perognathus goldmani and P. +artus. By E. Raymond Hall and Marilyn Bailey Ogilvie. Pp. 513-518, 1 map +in text. January 14, 1960.</li> + + <li>Records of harvest mice, Reithrodontomys, from Central America, with +description of a new subspecies from Nicaragua. By Sydney Anderson and J. +Knox Jones, Jr. Pp. 519-529. January 14, 1960.</li> + + <li>Small carnivores from San Josecito Cave (Pleistocene), Nuevo León, +México. By E. Raymond Hall. Pp. 531-538, 1 figure in text. January 14, +1960.</li> + + <li>Pleistocene pocket gophers from San Josecito Cave, Nuevo León, +México. By Robert J. Russell. Pp. 539-548, 1 figure in text, January 14, +1960.</li> + </ol></dd> + <dd>More numbers will appear in volume 9.</dd> + <dt><span class="pagenum"><a name="back_flap_out" id="back_flap_out">[Back Cover Outside]</a></span> + Vol. 10.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>Studies of birds killed in nocturnal migration. By Harrison B. +Tordoff and Robert M. Mengel. Pp. 1-44, 6 figures in text, 2 tables. +September 12, 1956.</li> + + <li>Comparative breeding behavior of Ammospiza caudacuta and A. +maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates, 1 figure. December +20, 1956.</li> + + <li>The forest habitat of the University of Kansas Natural History +Reservation. By Henry S. Fitch and Ronald R. McGregor. Pp. 77-127, 2 +plates, 7 figures in text, 4 tables. December 31, 1956.</li> + + <li>Aspects of reproduction and development in the prairie vole +(Microtus ochrogaster). By Henry S. Fitch. Pp. 129-161, 8 figures in +text, 4 tables. December 19, 1957.</li> + + <li>Birds found on the Arctic slope of northern Alaska. By James W. +Bee. Pp. 163-211, plates 9-10, 1 figure in text. March 12, 1958.</li> + + <li>The wood rats of Colorado: distribution and ecology. By Robert B. +Finley, Jr. Pp. 213-552, 34 plates, 8 figures in text, 35 tables. +November 7, 1958.</li> + + <li>Home ranges and movements of the eastern cottontail in Kansas. By +Donald W. Janes. Pp. 553-572, 4 plates, 3 figures in text. May 4, +1959.</li> + + <li>Natural history of the salamander Aneides hardyi. By Richard F. +Johnston and Gerhard A. Schad. Pp. 573-585. October 8, 1959.</li> + </ol></dd> + <dd>More numbers will appear in volume 10.</dd> + <dt>Vol. 11.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>The systematic status of the colubrid snake, Leptodeira discolor +Günther. By William E. Duellman. Pp. 1-9, 4 figures. July 14, 1958.</li> + + <li>Natural history of the six-lined racerunner, Cnemidophorus +sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figures, 9 tables. September +19, 1958.</li> + + <li>Home ranges, territories, and seasonal movements of vertebrates +of the Natural History Reservation. By Henry S. Fitch. Pp. 63-326, 6 +plates, 24 figures in text, 3 tables. December 12, 1958.</li> + + <li>A new snake of the genus Geophis from Chihuahua, Mexico. By John +M. Legler. Pp. 327-334, 2 figures in text. January 28, 1959.</li> + + <li>A new tortoise, genus Gopherus, from north-central Mexico. By +John M. Legler. Pp. 335-343. April 24, 1959.</li> + + <li>Fishes of Chautauqua, Cowley and Elk counties, Kansas. By Artie +L. Metcalf. Pp. 345-400, 2 plates, 2 figures in text, 10 tables. May 6, +1959.</li> + + <li>Fishes of the Big Blue River Basin, Kansas. By W. L. Minckley. +Pp. 401-442, 2 plates, 4 figures in text, 5 tables. May 8, 1959.</li> + + <li>Birds from Coahuila, México. By Emil K. Urban. Pp. 443-516. +August 1, 1959.</li> + + <li>Description of a new softshell turtle from the southeastern +United States. By Robert G. Webb. Pp. 517-525, 2 plates, 1 figure in +text. August 14, 1959.</li> + </ol></dd> + <dd>Another number will appear in volume 11.</dd> + <dt>Vol. 12.</dt> + <dd class="small_margin"> + <ol class="start_1"> + <li>Functional morphology of three bats: Eumops, Myotis, Macrotus. By +Terry A. Vaughan. Pp. 1-153, 4 plates, 24 figures in text. July 8, +1959.</li> + + <li>The ancestry of modern Amphibia: a review of the evidence. By +Theodore H. Eaton, Jr. Pp. 155-180, 10 figures in text. July 10, +1959.</li> + + <li>The baculum in microtine rodents. By Sydney Anderson. Pp. +181-216, 49 figures in text. February 19, 1960.</li> + </ol></dd> + <dd>More numbers will appear in volume 12.</dd> + </dl> + + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of The Baculum in Microtine Rodents, by +Sydney Anderson + +*** END OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + +***** This file should be named 38021-h.htm or 38021-h.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/8/0/2/38021/ + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. + + +</pre> + +</body> +</html> diff --git a/38021-h/images/001.jpg b/38021-h/images/001.jpg Binary files differnew file mode 100644 index 0000000..28f470e --- /dev/null +++ b/38021-h/images/001.jpg diff --git a/38021-h/images/184a.jpg b/38021-h/images/184a.jpg Binary files differnew file mode 100644 index 0000000..537658d --- /dev/null +++ b/38021-h/images/184a.jpg diff --git a/38021-h/images/184b.jpg b/38021-h/images/184b.jpg Binary files differnew file mode 100644 index 0000000..a897f19 --- /dev/null +++ b/38021-h/images/184b.jpg diff --git a/38021-h/images/188.jpg b/38021-h/images/188.jpg Binary files differnew file mode 100644 index 0000000..273eb87 --- /dev/null +++ b/38021-h/images/188.jpg diff --git a/38021-h/images/189.jpg b/38021-h/images/189.jpg Binary files differnew file mode 100644 index 0000000..6981851 --- /dev/null +++ b/38021-h/images/189.jpg diff --git a/38021-h/images/190.jpg b/38021-h/images/190.jpg Binary files differnew file mode 100644 index 0000000..278bc85 --- /dev/null +++ b/38021-h/images/190.jpg diff --git a/38021-h/images/191.jpg b/38021-h/images/191.jpg Binary files differnew file mode 100644 index 0000000..faca13b --- /dev/null +++ b/38021-h/images/191.jpg diff --git a/38021.txt b/38021.txt new file mode 100644 index 0000000..3fea25c --- /dev/null +++ b/38021.txt @@ -0,0 +1,2698 @@ +Project Gutenberg's The Baculum in Microtine Rodents, by Sydney Anderson + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Baculum in Microtine Rodents + +Author: Sydney Anderson + +Release Date: November 15, 2011 [EBook #38021] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + + + + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + + + + + + + UNIVERSITY OF KANSAS PUBLICATIONS + MUSEUM OF NATURAL HISTORY + + Volume 12, No. 3, pp. 181-216, 49 figs. + + February 19, 1960 + + The Baculum in Microtine Rodents + + BY + SYDNEY ANDERSON + + UNIVERSITY OF KANSAS + LAWRENCE + 1960 + + UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY + + Editors: E. Raymond Hall, Chairman, Henry S. Fitch, + Robert W. Wilson + + Volume 12, No. 3, pp. 181-216, 49 figs. + Published February 19, 1960 + + UNIVERSITY OF KANSAS + Lawrence, Kansas + + PRINTED IN + THE STATE PRINTING PLANT + TOPEKA, KANSAS + 1960 + +[Illustration] + + 28-774 + + + + +The Baculum in Microtine Rodents + +BY + +SYDNEY ANDERSON + +INTRODUCTION + + +Didier (1943, 1954) has described the bacula of several Old World +microtines, and other rodents. Argyropulo studied (1933a, 1933b) five +species of Cricetinae and _Microtus socialis_. Ognev (1950) illustrated +numerous species of Eurasian microtines. Hamilton (1946) figured and +described the baculum of 11 species of North American microtines. Hibbard +and Rinker (1942, 1943) figured the baculum of _Synaptomys cooperi +paludis_ and of _Microtus ochrogaster taylori_. Dearden (1958) studied +the baculum in two Asiatic species of _Lagurus_, in six subspecies of +_Lagurus curtatus_ of North America, and in six other species of +microtines of other genera. + +The baculum can be preserved easily with standard study skins, and is +potentially useful in interpreting relationships on any taxonomic level, +and especially in determining the relationships of species within a +genus, if used together with other structures. + +The anatomical orientation of the baculum needs comment because some +confusion exists in the literature, especially concerning the use of the +terms ventral and dorsal. The urethra lies on the anatomically ventral +side of the penis, and of the baculum. In the center of the penis lies a +single corpus cavernosum penis, shown in cross section proximal to the +baculum in Figure 1c. Dorsally an artery, thinner walled than the ventral +urethra, ends in a somewhat reticulate sinus surrounding primarily the +middle part of the baculum within the bulbous glans penis. The corpus +cavernosum penis (the structure has no median septum, at least distally) +terminates with the baculum and is closely knit to it. The site of this +bond is evident in the tuberosities and sculpturing of the base of the +baculum. + +The part of the penis enclosing the baculum, when not erect, is folded +back as shown in Figures 1a and 1b. As a result the anatomically ventral +surface faces upwards, or at least posterodorsally. The use of the term +ventral in this account refers to the anatomically ventral side, that is +to say to the side of the baculum facing the urethra. + +The baculum in microtines consists of an elongate stalk, having a +laterally, and to a lesser extent dorsoventrally, expanded base and an +attenuate distal shaft. Usually, three digitate processes of +cartilaginous material in which additional ossifications may occur arise +from the terminus of the shaft. The proportions and curvature of the +stalk vary as do the proportions of the terminal ossifications to each +other and to the stalk. In some species one or more of the digital +processes are frequently completely unossified. + +[Illustration: FIGURE 1. The baculum in _Microtus +ochrogaster_--orientation and variation with age. _a._ Diagram of a +sagittal section of the posterior half of a vole, natural size. The +penis, containing the baculum (in black), extends ventrally from a point +posterior to the pubic symphysis (stippled), along the body wall, and +bends posteriorly at the distal end. _b._ Distal end of penis (x 2) +showing baculum (in black), the urethra (solid lines) adjacent to the +baculum, and the corpus cavernosum (broken lines) proximal to the +baculum. _c._ Oblique view of the cross section of penis (x 4) shown in +Figure 1 _b_. The thick-walled urethra lies ventral to the curved corpus +cavernosum. A thinner-walled blood-vessel lies dorsal to the corpus +cavernosum. The anatomically ventral side of the baculum, in the normal +non-erect penis shown, is seen to face dorsally. _d._ Graph showing the +relationship between size of baculum, size of animal, and development of +digital ossifications. Circles show presence of ossification in stalk +only; circles enclosing dots indicate presence of secondary ossification +in median process also; large dots indicate the addition of tertiary +ossification in one or both of the lateral digitate processes.] + +Preserved specimens of _Microtus arvalis_, _Microtus agrestis_, _Microtus +orcadensis_, _Microtus nivalis_, _Microtus guentheri_, _Microtus +subterraneus_, _Clethrionomys glareolus_, and _Ellobius lutescens_ were +provided by Prof. Robert Matthey of Lausanne, Switzerland. J. Knox Jones, +Jr. carefully saved the bacula with specimens of _Microtus fortis_ and +_Clethrionomys rufocanus_ from Korea. Dr. W. B. Quay, Department of +Zoology, University of California, supplied specimens of _Synaptomys +cooperi_, _Phenacomys intermedius_, and _Microtus oregoni_. Dr. Franklin +Sturges and Mr. John W. Goertz, Museum of Natural History, Oregon State +College, Corvallis, have provided specimens including bacula of +_Clethrionomys occidentalis_, _Microtus oregoni_, and _Microtus +townsendii_. Dr. Randolph L. Peterson and Mr. Bristol Foster, Royal +Ontario Museum of Zoology, Toronto, Canada, provided specimens of +_Phenacomys intermedius_. Dr. J. N. Layne, University of Florida, +Gainsville, Florida, presented me with a baculum of _Microtus parvulus_. + +I am indebted to all of these persons for their aid, and to various +collectors for the Museum of Natural History, who preserved bacula with +specimens. Many of these specimens were obtained through the assistance +of the University of Kansas Endowment Association and the National +Science Foundation. + + + + +METHODS + + +Bacula were obtained from fresh specimens, specimens preserved in alcohol +or formalin, and dried study skins. The processing of bacula has been +discussed by Hamilton (1946), Friley (1947), White (1951), and Dearden +(1958). The methods used to preserve bacula for my study differed some +from any of those reported. The terminal part of each penis including the +baculum imbedded in the glans penis was removed in its entirety and +placed in a vial. The catalogue number was kept with each specimen at all +times. A two per cent solution of potassium hydroxide was added. All +specimens were examined at least once a day. If tissues other than the +glans penis were present they were removed with forceps when softened +usually at the end of one day. Several drops of Alizarin red-S stain in a +saturated alcoholic solution were added to the 3 to 5 ccs. of KOH +solution in each vial. Solutions were replaced if they became turbid +enough to obstruct observation of the clearing penis. After one day the +solution containing stain was removed and replaced with two per cent KOH +solution without stain. When the glans became sufficiently cleared that +the stained baculum could be seen easily, the solution was replaced by +glycerin in which clearing was completed. The time required for the +entire process varied from one day to more than two weeks depending on +the size of the specimen and on its condition. Fresh specimens clear more +rapidly than dried specimens, and those that are dried more rapidly than +those that are preserved. A three or four per cent solution of hydroxide +will hasten the process, but more frequent observation is required to +prevent excessive maceration. + +Specimens were then examined in a shallow dish containing glycerin under +a binocular microscope. The baculum can be viewed from any desired +direction. The method described above leaves the baculum intact within +the glans penis; therefore its orientation can be determined relative to +the thick walled urethra and the thin walled dorsal artery that extends +onto the dorsal side of the baculum. The ventral curvature of the penis +proximal to the baculum, and the distal extension, characteristic of most +species, of the dorsal border of the glans (both shown in Figure 1) are +other features aiding in correctly orienting cleared specimens. The +digitate processes are not so often injured, lost, or displaced when the +method described above is used as they are when the penis is dissected. +Specimens were stored in glycerin in glass shell vials having +polyethylene stoppers. A small card bearing the name, number, locality, +and other data was placed in each vial. A specimen thus enclosed can be +kept indefinitely, or removed and mounted in balsam as described by White +(1951:631) or in plastic as described by Dearden (1958:541) and thus +stored in the vial containing the skull of the specimen. + +Drawings were made on millimeter ruled paper while the baculum was viewed +under a binocular microscope with a square ruled eyepiece. + +Unless otherwise noted all specimens listed are in the University of +Kansas Museum of Natural History. Catalogue numbers are cited. +Measurements are accurate to within less than one-tenth of a millimeter. +Proportions as stated in the text are approximations, accurate to within +one-twelfth (8.33 per cent). The range of variation is unknown for some +species. Mention is made if maturity is known or suspected to differ in +specimens being compared. + +The development of the baculum has been studied by Callery (1951) in +_Mesocricetus auratus_ and by Ruth (1934) in the laboratory rat. In the +rat (_Rattus norvegicus_) the bone is of endoblastemal origin being laid +down by a condensation of undifferentiated mesenchymal cells. At the +distal end of the bone dense fibrous tissue is then differentiated and at +the proximal end hyaline cartilage. Growth is by substitution at the +proximal end and by subperiosteal lamellation circumferentially. A marrow +cavity is formed by resorption. In the baculum of the hamster the primary +center of ossification is in the stalk, and is present at the age of +three days; the secondary centers are in lateral processes and are +present at 80 days and enlarge subsequently. A tertiary center, in each +median process, may or may not develop later. Maximum development of the +baculum is reached late in the reproductive life of the hamster. + +The early ossification of the baculum noted in the rat and the hamster +occurs in _Microtus_ also. A specimen of _Microtus montanus fusus_ +(76831, from 5 mi. N, 26 mi. W Saguache, 9600 ft., Saguache County, +Colorado) only 74 mm. in total length and weighing only 6.6 grams, had a +slender ossified baculum having enlarged ends. This vole was one-half of +the average length and less than one-fifth of the average weight of an +adult, and of approximately the size at which weaning takes place. + +The development of the baculum in _Microtus ochrogaster_ was studied in +32 specimens of various ages. The specimens (between Nos. 74994 and +75074) were collected between August 15 and September 4, 1957, at +localities on the Great Plains. These specimens were from breeding +populations, as evidenced by pregnancy of females and by large size of +testes of males. The length and width of the stalk of the baculum, the +presence of digital ossifications, the total length of the animal, and +the size of the testes were noted. Variability in length of testes is +greatest when voles are from 140 to 150 mm. in total length. Sexual +maturity is reached rather abruptly when the total length of most +individuals is 140 to 150 millimeters. If the baculum likewise underwent +more rapid growth at the onset of sexual maturity, greater variability +should be evident in the length of the baculum of voles 140 to 150 mm. in +total length than in bacula of voles of other sizes. This was the case +(see Figure 1d). The baculum does not, however, suddenly reach its +maximum maturity. + +The primary ossification is in the stalk. The secondary ossification is +in the median process except in _Lagurus_ (Dearden, 1958:551) and some +individuals of _Neofiber_ (see account on page 258). Tertiary centers of +ossification are in the lateral processes. The primary ossification is +present at an early age and subsequently increases in size and solidity. +The secondary and tertiary ossifications are progressively more common in +older voles. The increase in degree of ossification of all parts +continues after sexual maturity is reached. Individual variation and +variation with age in the baculum of _Microtus pennsylvanicus_ have been +illustrated by Hamilton (1946:380). Figures 14, 15, and 17 illustrate +variation with size, which is correlated with age, and also illustrate +individual variation. The three bacula are from adult voles having testes +that measured 15, 16 and 16 mm. in length, respectively. Each vole was +trapped in late June. The total lengths in millimeters of the three voles +are 172, 167, and 181; weights are 55, 52.4, and 65.5 grams. I judge that +the greater size of the stalk and the better developed base shown in +Figure 17 than in Figure 15 are illustrative of age variation; the +difference in the size of the lateral digitate processes is, in this +case, attributable to individual variation. Differences in the distal end +of the baculum in Figures 42 and 43, show individual variation also. +Figures 35 and 36 represent two different subspecies; different +individuals of _M. mexicanus mogollonensis_, however, exhibit individual +variation of the same degree. + +Hall and Cockrum (1953) list 44 species of microtines in North America. +At least twelve of these are insular or local forms perhaps derived from +some other species; for example _Microtus coronarius_, an insular form +derived from _Microtus longicaudus_; _Microtus provectus_, considered by +Chamberlain (1954:587) and by Wheeler (1956:176) as a subspecies of +_Microtus pennsylvanicus_; and _Microtus ludovicianus_, a close relative +of _Microtus ochrogaster_. + +All North American genera have been studied. Of the genus _Microtus_ in +North America, all subgenera but _Orthriomys_ and all species but the +following nine, have been studied: _M. (Orthriomys) umbrosus_, the +insular _M. (Stenocranius) abbreviatus_, _M. (Microtus) breweri_, _M. +(Microtus) nesophilus_, _M._ + +[Illustration: FIGURES 2-13. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. Exact localities are +given in accounts of species concerned. + +2. _Lemmus trimucronatus_, 50678, Point Barrow, Alaska. + +3. _Dicrostonyx groenlandicus_, 50539, Porcupine Lake, Brooks Range, +Alaska. + +4. _Dicrostonyx groenlandicus_, 52524, Point Barrow, Alaska. + +5. _Synaptomys cooperi saturatus_, WBQ 3-C-454, 3 mi. S Demotte, Indiana. + +6. _Synaptomys cooperi paludis_, 13716, Meade County State Park, Kansas. + +7. _Phenacomys intermedius celatus_, SA 2044, Quebec. + +8. _Phenacomys intermedius intermedius_, WBQ 3-C-309, 5.4 mi. S Moran, +Teton Co., Wyoming. + +9. _Clethrionomys rufocanus_, 60438, 1 mi. NW Oho-ri, Korea, (_d_) +ventral view. + +10. _Clethrionomys gapperi_, 42108, 31 mi. N Pinedale, Wyoming. + +11. _Clethrionomys rutilus_, 42865, 5 mi. NNE Gulkana, Alaska. + +12. _Clethrionomys occidentalis_, FWS 30, Mary's Peak, Benton Co., +Oregon. + +13. _Clethrionomys glareolus_, 67100, Zermatt, Valais, Switzerland.] + +[Illustration: FIGURES 14-25. Bacula of _Microtus_. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with dorsal surface upward. + +14. _M. pennsylvanicus_, 42439, 1 mi. S, 2 mi. E Eagle Nest, Colfax Co., +New Mexico; abnormality perhaps owing to injury; dorsal view. + +15. _M. pennsylvanicus_, 42306, 5 mi. N, 26 mi. W Saguache, Colorado; +dorsal view. + +16. _M. pennsylvanicus_, 43043, 20 mi. NE Anchorage, Alaska, ventral +view. + +17. _M. pennsylvanicus_, 42430, 1 mi. S, 2 mi. E Eagle Nest, New Mexico. + +18. _M. agrestis_, 67102, Gryon, Switzerland. + +19. _M. montanus amosus_, 62241, 1/2 mi. E Soldier Summit, Wasatch Co., +Utah. + +20. _M. montanus nanus_, 57470, 2 mi. N, 2 mi. W Pocatello, Idaho. + +21. _M. montanus fusus_, 42307, 5 mi. N, 26 mi. W Saguache, Colorado. + +22. _M. arvalis_, 67101, Vidy, Switzerland, possibly not mature. + +23. _M. guentheri_, 67104, Palestine. + +24. _M. orcadensis_, 67106, Orkney Islands, orientation uncertain. + +25. _M. fortis_, 63841, Chipo-ri, Korea, (_d_) ventral view.] + +[Illustration: FIGURES 26-39. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. + +26. _M. (Pitymys) fatioi_, 67103, Zermatt, Switzerland, immature. + +27. _M. (Pitymys) pinetorum_, 76834, 2 mi. N Baldwin, Douglas Co., +Kansas. + +28. _M. (Pitymys) pinetorum_, 68545, 1 mi. NE Pleasant Grove, Kansas. + +29. _M. (Pitymys) quasiator_, 30709, Teocelo, Veracruz, (_d_) ventral +view. + +30. _M. (Pitymys) quasiator_, 19878, 5 km. N Jalapa, Veracruz. + +31. _M. (Pedomys) ochrogaster_, 75036, 1 mi. N, 2 mi. E Oberlin, Kansas. + +32. _M. (Stenocranius) miurus_, 51152, Lake Schrader, Brooks Range, +Alaska. + +33. _M. (Stenocranius) miurus_, 51169, Lake Schrader, Brooks Range, +Alaska. + +34. _M. (Stenocranius) gregalis_, 8059, "Eastern Europe." + +35. _M. mexicanus mexicanus_, 63094, Valle de Bravo, Estado de Mexico, +Mexico. + +36. _M. mexicanus mogollonensis_, 63298, Mt. Taylor, Valencia Co., New +Mexico. + +37. _M. californicus_, 76828, 1 mi. NE Berkeley, California; (_d_) +ventral view. + +38. _M. (Arvicola) richardsoni_, 42454, 31 mi. N Pinedale, Sublette Co., +Wyoming. + +39. _M. richardsoni_, 37903, 23-1/2 mi. S, 5 mi. W Lander, Wyoming; +distal end.] + +[Illustration: FIGURES 40-49. Bacula of microtines. Unless indicated +otherwise views are (_a_) of the dorsum, (_b_) the right side, and (_c_) +the proximal end with the dorsal surface upward. + +40. _Microtus (Pitymys) parvulus_, UF 1508, 1 mi. W Micanopy, Florida. + +41. _Microtus townsendii_, 79186, Sec. 33, T. 11S, R. 5W, Benton Co., +Oregon. + +42. _Microtus (Herpetomys) guatemalensis_, 65895, 2 mi. S San Juan Ixcoy, +Guatemala. + +43. _M. guatemalensis_, 65921, 10 mi. E, 4 mi. S Totonicapan, Guatemala, +dorsal view of tip. + +44. _Microtus oeconomus_, 43048, Kelsall Lake, British Columbia. + +45. _Microtus (Chilotus) oregoni_, WBQ 3-C-248, 5 mi. N Orick, +California. + +46. _Lagurus (Lemmiscus) curtatus_, 26053, 9 mi. S Robertson, Uinta Co., +Wyoming. + +47. _Microtus (Chionomys) nivalis_, 65127, Wetterstein, Germany, +orientation uncertain. + +48. _Microtus (Chionomys) longicaudus_, 50253, Crane Flat, Mariposa Co., +California. + +49. _Neofiber alleni_, 27268, 2 mi. S Gainesville, Florida, orientation +uncertain.] + +(_Microtus_) _provectus_ (the last three are probably insular derivatives +of _M. pennsylvanicus_), _M._ (_Microtus_) _fulviventer_ (perhaps derived +from the same stock as _Microtus mexicanus_), _M._ (_Microtus_) +_xanthognathus_ (perhaps related to _Microtus chrotorrhinus_), _M._ +(_Microtus_) _coronarius_, and _M._ (_Pedomys_) _ludovicianus_. + + +SPECIES OF WHICH BACULA WERE EXAMINED + + Subfamily: Microtinae Number of Specimens + Tribe: Lemmi + _Dicrostonyx groenlandicus_ (Traill) 4 + _Lemmus trimucronatus_ (Richardson) 6 + _Synaptomys cooperi_ Baird 5 + Tribe: Microti + Genus: _Clethrionomys_ Tilesius, 1850 + _Clethrionomys rutilus_ Pallas 4 + _Clethrionomys gapperi_ (Vigors) 9 + _Clethrionomys occidentalis_ (Merriam) 1 + _Clethrionomys glareolus_ Schreber 1 + _Clethrionomys rufocanus_ Sundevall 1 + Genus: _Phenacomys_ Merriam, 1897 + _Phenacomys intermedius_ Merriam 5 + Genus: _Ondatra_ Link, 1795 + _Ondatra zibethicus_ (Linnaeus) 1 + Genus: _Microtus_ Schrank, 1798 + (_Herpetomys_) _guatemalensis_ Merriam 3 + (_Arvicola_) _richardsoni_ (DeKay) 2 + (_Chilotus_) _oregoni_ (Bachman) 3 + (_Stenocranius_) _gregalis_ (Pallas) 1 + (_Stenocranius_) _miurus_ Osgood 9 + (_Chionomys_) _longicaudus_ (Merriam) 6 + (_Chionomys_) _nivalis_ Martins 2 + (_Microtus_) _arvalis_ (Pallas) 1 + (_Microtus_) _orcadensis_ Millais 1 + (_Microtus_) _guentheri_ Danford and Alston 1 + (_Microtus_) _fortis_ Buechner 2 + (_Microtus_) _montanus_ (Peale) 15 + (_Microtus_) _townsendii_ (Bachman) 3 + (_Microtus_) _oeconomus_ (Pallas) 10 + (_Microtus_) _mexicanus_ (Saussure) 13 + (_Microtus_) _californicus_ (Peale) 2 + (_Microtus_) _pennsylvanicus_ (Ord) 13 + (_Microtus_) _agrestis_ (Linnaeus) 1 + (_Pedomys_) _ochrogaster_ (Wagner) 41 + (_Pitymys_) _pinetorum_ (LeConte) 2 + (_Pitymys_) _parvulus_ (Howell) 1 + (_Pitymys_) _quasiater_ (Coues) 5 + (_Pitymys_) _fatioi_ Mottaz 1 + Genus: _Neofiber_ True, 1884 + _Neofiber alleni_ True 2 + Genus: _Lagurus_ Gloger, 1841 + _Lagurus curtatus_ (Cope) 7 + + Total number examined 184 + + + + +ACCOUNTS OF SPECIES + + +Dicrostonyx groenlandicus (Traill) + +Figs. 3 and 4 + +Baculum: stalk elongate, greatest length (3.1 mm.) 2-1/5 to 2-1/2 times +greatest breadth, and 4-1/2 times greatest depth; digitate processes +usually cartilaginous, occasionally lateral processes partly ossified; +basal tuberosities weakly to moderately developed, medially confluent; +posterior profile in dorsal view rounded with rounded posterior apex or +shallow notch; dorsal concavity in end-view shallower and not so wide as +ventral concavity; median constriction approximately 2/3 greatest depth; +ventral part of base in end-view wider than dorsal part; shaft straight +or slightly curved; base of stalk placed dorsally relative to axis of +shaft; stalk spatulate, sometimes with distal enlargement; at mid-point +stalk wider than high; lateral profile in dorsal view sloping gradually +without abrupt curvature anterior to point of greatest width. + +The baculum of _Dicrostonyx torquatus_ figured by Ognev (1948:476) agrees +with that of _D. groenlandicus_ in shape of stalk, and in lateral +digitate processes that are small relative to size of median process; but +differs in more elongate, terminally enlarged, bulbar shape of median +process. None of my specimens showed ossification in the lateral +processes, observed by Hamilton (1946:381) in _Dicrostonyx rubricatus +richardsoni_ [ = _D. groenlandicus richardsoni_]. In all of my specimens +the cartilaginous median process was larger than that figured by +Hamilton, or by Dearden (1958:542). + +_Specimens examined_: Four from; Point Barrow, Alaska, 52524 (Barrow +Village), 67264 (died in captivity); Brooks Range, Alaska, 50536 (Wahoo +Lake, 69 deg.08', 146 deg.58'), 50539 (Porcupine Lake, 68 deg.51'57", 146 deg.29'50", +3140 ft.). + + +Lemmus trimucronatus (Richardson) + +Fig. 2 + +Baculum: Stalk heavy, broad, greatest length (2.8 mm.) in mature +individuals (Fig. 2) as little as 1-1/3 times greatest breadth, greatest +length no less than 2-2/3 times greatest depth of base; three ossified +processes, median one from as long as to 1/2 longer than the lateral +processes, and approximately 2/3 wider and twice as deep as lateral +processes; length of median process almost 3-1/2 times its breadth, +approximately 1/2 length of stalk; basal fossae broadly confluent; +posterior profile in dorsal view evenly rounded; in end-view ventral +concavity deeper than dorsal concavity, constriction as little as 1/2 +greatest depth in mature specimens; shaft straight, bluntly rounded, or +slightly decurved and laterally inflated terminally; lateral profile in +dorsal view a gradual slope from widest point of stalk anteriorly onto +shaft; in younger individuals stalk slenderer, otherwise as described +above. + +Five specimens examined by me differ from one figured and described by +Hamilton (1946:379) in that stalk is better developed, larger relative to +size of processes, length of stalk in my specimen (Fig. 2) 2.8 as opposed +to 2.1 mm. in Hamilton's specimen; median process shorter, 1.5 as opposed +to 1.8 mm., proximal end rounded rather than concave, not partially +enclosing tip of shaft; proportion of and relative sizes of median and +lateral processes approximately same as in Hamilton's _Lemmus helvolus_ +[ = _Lemmus trimucronatus helvolus_]. A specimen figured by Dearden +(1958:542) has a basally trilobed median process. + +The baculum of the Asiatic _Lemmus lemmus_ figured by Ognev (1948:413) +agrees with my specimens in the ossification of three processes, the +relative sizes of these processes to each other and to the stalk, the +well-developed base of the stalk and heavy bluntly rounded shaft; the +baculum of _Lemmus lemmus_ differs in greater anterolateral extent of +basal tuberosities, in proximal notch seemingly separating these +tuberosities, and in median process being slenderer. + +_Specimens examined_: Five, of two subspecies; _Lemmus trimucronatus +alascensis_, Point Barrow, Alaska, numbers 50591, 50678, 50731, 50758; +_Lemmus trimucronatus subarcticus_, Wahoo Lake, 69 deg.08', 146 deg.58', 2350 +ft., Brooks Range, Alaska, 50948. + + +Synaptomys cooperi Baird + +Figs. 5 and 6 + +Baculum: Stalk elongate, greatest length (2.7 to 2.8 mm.) 2-1/3 to 2-1/2 +times greatest breadth, 4 to 5 times greatest depth; three processes +ossified or lateral processes unossified, ossifications relatively small +(in 78380, median ossification less than 1/4 as large as lateral +ossifications although median cartilaginous process is larger), length of +median process 1/5 to 1/6 of length of stalk, cartilaginous part of +median process larger; posterior profile in dorsal view convex throughout +or bilobate; tuberosities moderately developed, deflected dorsal to axis +of shaft; in end-view medial construction 3/5 greatest depth of +tuberosities; shaft tapered from point of greatest width, slightly +inflated terminally. + +The specimen (KU 13716) figured by Hibbard and Rinker (1942:29) has been +restudied. It was first cleared and stained to soften the dry cartilage +binding the digital processes together and to differentiate bone and +cartilage. The lateral processes are small and cartilaginous (Fig. 6) and +seem intact. The differences between this specimen and others examined by +Hamilton (1946:381), Dearden (1958:542), and myself, namely the +relatively larger median ossification, the absence of ossification in +lateral processes, and the distinctly bilobate base and larger size, may +represent geographic differences, or individual variation. The +proportions of length, width, and depth of the stalk, and the appearance +in lateral view do not differ greatly from others examined by Hamilton, +by Dearden (1958:546), and by me. + +_Specimens examined_: Five, representing four subspecies; _S. cooperi +gossii_, 6 mi. N Midway, Holt Co., Nebraska 78379, 78380; _S. cooperi +relictus_, 5 mi. N, 2 mi. W Parks, Dundy Co., Nebraska, 72601 (immature); +_S. cooperi saturatus_, 3 mi. S Demotte, Jasper Co., Indiana, 3-C-454, +collection of W. B. Quay; _S. cooperi paludis_, Meade County State Park, +Kansas, 13716. + + +Clethrionomys rutilus Pallas + +Fig. 11 + +Baculum: Stalk elongate, and proximally enlarged, greatest length (2.7 +mm.) 2 times greatest breadth; less than 4 times greatest depth; three +well-developed ossified processes; length of stalk 2-1/3 times length of +median process; median process with basal (and ventral) protuberence and +lateral lobes, arched in dorsoventral plane; lateral processes as large +as median process, flattened distally, having ventromedial vane on distal +half; basal tuberosities of stalk well developed, medially confluent; +posterior profile in dorsal view trilobate or convex throughout with +rounded posterior apex; dorsal concavity well developed, ventral surface +but slightly concave, medial constriction of base as little as 1/2 +greatest depth; shaft straight, slender, at mid-point of stalk but +slightly wider than high; basal tuberosities largely dorsal to axis of +shaft in lateral view; lateral profile in dorsal view with an abrupt +curvature separating the gently sloping sides of the shaft from the basal +part at its greatest breadth. + +The specimen of _Clethrionomys rutilus_ figured by Ognev (1950:120) is +essentially like the North American specimens examined by me in the +relative sizes of the ossifications and the general shape of the stalk. + +_Specimens examined_: Four, of one subspecies; _C. r. dawsoni_, west bank +Gakona River, 1700 ft., 5 mi. NNE Gulkana, Alaska, 42865, 42866; SW end +Dezadeash Lake, 2400 ft., Yukon Territory, 42910, 42921. + + +Clethrionomys gapperi (Vigors) + +Fig. 10 + +Baculum: Stalk elongate, greatest length (2.8 mm.) 1-3/4 times greatest +breadth, and 3-3/4 times greatest depth; proximally enlarged, greatest +depth 1/2 greatest breadth; three well-developed ossified processes; +length of stalk 2-1/3 times length of median process; median process +arched in dorsoventral plane, with basiventral protuberence or spine and +lateral lobes; lateral processes as large as median process, flattened +distally, arched; basal tuberosities of stalk well developed, medially +confluent; posterior profile in dorsal view trilobate or convex +throughout with a rounded posterior apex; dorsal concavity well +developed, ventral surface but slightly concave, or in some cases +slightly convex; medial constriction of base 3/5 greatest depth; shaft +straight, slender, at mid-point of stalk twice as wide as high; basal +tuberosities dorsally placed relative to axis of shaft; lateral profile +in dorsal view abruptly curved anterior to point of greatest width; +slender stalk distinct from angular enlarged base. + +The most noticeable difference between the baculum of _C. rutilus_ and +_C. gapperi_ is size. The proportions of the four ossifications are +approximately the same. Ventral vanes on the lateral processes are not +developed in _C. gapperi_. _C. gapperi_ and _C. rutilus_ are more nearly +alike in their bacula than any other two species of _Clethrionomys_ +examined. _Clethrionomys occidentalis_, the other New World species, is +also much like _C. gapperi_ and _C. rutilus_. The differences are of a +magnitude comparable to those between the bacula in subspecies of +_Microtus montanus_ (Figs. 19-21) for example, or in subspecies of +_Lagurus curtatus_ (Dearden, 1958:542). + +_Specimens examined_: Nine, of two subspecies; _Clethrionomys gapperi +athabascae_, British Columbia, 42922 (Indian Creek, Mile Post 234 of +Alaskan Highway), 64281 (West bank Racing River, 89 mi. W Muskwa), 64287 +(North bank Tetsa River, 56 mi. W, 11 mi. S Muskwa), 64290 (44 mi. W, 9 +mi. S Muskwa), 64310 (32 mi. W, 2 mi. S Muskwa); _Clethrionomys gapperi +galei_, 31 mi. N Pinedale, Sublette Co., Wyoming, 42108; Grand Mesa, +Delta Co., Colorado, 60014 and 60015 (5-1/2 mi. E, 12 mi. S Collbran), +60022 (8 mi. E, 1/2 mi. S Skyway). + + +Clethrionomys occidentalis (Merriam) + +Fig. 12 + +Baculum: Stalk elongate, greatest length (2.8 mm.) 2-1/2 times greatest +breadth, 6 times greatest depth; three well-developed ossified processes; +median process larger than lateral processes, 1/2 the length of stalk, +curved, basally broad, ventrally keeled, trilobate posteriorly; lateral +ossifications large, flattened distally, curved; posterior profile of +stalk posteriorly slightly emarginate, thus bilobate in outline; in +end-view dorsal concavity deeper than ventral, constriction less than 1/2 +greatest depth, tuberosities confluent, visible in dorsal view at each +side; shaft slender, especially in depth, straight; at mid-point of stalk +almost twice as wide as deep, slight terminal inflation. + +The general proportions of the stalk and the relatively large, uniquely +shaped processes, are characteristic of most specimens of the genus +_Clethrionomys_ examined. + +_Specimen examined_: _C. occidentalis californicus_, one from Mary's +Peak, Benton Co., Oregon, 30, F. W. Sturges' collection. + + +Clethrionomys glareolus Schreber + +Fig. 13 + +Baculum: Stalk elongate, greatest length (2.9 mm.) twice the greatest +breadth in the specimen examined, flattened proximally, greatest length +almost 6 times greatest depth of base; three well-developed ossified +processes; median process arched in a dorsoventral plane, with basal +notch and lateral lobes; lateral processes as long as median process, +bowed in dorsal view, flattened distally, with ventromedial vane; basal +tuberosities of stalk weakly developed, medially confluent; posterior +profile in dorsal view evenly rounded; in end-view dorsal concavity +shallow in comparison to most species but deeper than ventral concavity, +constriction 3/4 greatest depth; shaft straight, at mid-point slightly +wider than high, elongate, widest point of stalk less than 1/4 of total +length from proximal end, slight lateral inflation at tip; lateral +profile in dorsal view sloping at first abruptly and then gradually from +widest point of stalk anteriorly onto shaft. + +The specimen of _Clethrionomys glareolus_ figured by Ognev (1950:31) in +dorsal view as I interpret it, resembles my specimen in the rounded base; +in the elongate, distally inflated shaft; in the initially abrupt slope +of the lateral profile in dorsal view from the greatest width of stalk +anteriorly; and in the presence of three well ossified processes. Ognev's +specimen differs from mine in the median process being more elongate +relative to its width, and rounded proximally, lacking lateral lobes and +basal notch; in lateral processes being less curved; in the greater +terminal inflation of the shaft; and in the closer approximation of the +terminal processes to the shaft. The baculum of _Clethrionomys glareolus_ +as described and figured by Didier (1954:243-244) resembles my specimen +in general proportions, but is more pointed proximally and more curved in +dorsoventral plane. Didier states that the baculum is rather variable in +form in this species, in different regions, but that a large number of +specimens must be examined to assess the geographic nature of this +variation. + +_Specimen examined_: One from Zermatt, Valais, Switzerland, 67100. + + +Clethrionomys rufocanus Sundevall + +Fig. 9 + +Baculum: Base of stalk broad but relatively flattened dorsoventrally, +greatest length (3.2 mm.) less than 1-1/2 greatest width, 4 times +greatest depth; three well-developed ossified processes; median process +arched in dorsoventral plane, having basal notch and lateral lobes; +lateral processes as long as median process, flattened distally, with +ventromedial vane; basal tuberosities of stalk weakly developed, medially +confluent; posterior profile in dorsal view convex with rounded posterior +apex; dorsal surface of base almost flat, ventral concavity broad and +shallow; constriction 3/4 greatest depth (not including an unusual +irregularity on the ventral surface of the base); shaft straight, at +mid-point of stalk distinctly wider than high, slender at distal end, +widest point of stalk almost 1/3 of total length from proximal end, tip +of shaft rounded; lateral profile in dorsal view gradually sloping from +widest point anteriorly onto shaft. + +The specimen of _Clethrionomys rufocanus_ figured by Ognev (1950:97) +resembles my specimen in the presence of three well ossified processes. +Ognev's specimen differs however in the lack of a proximal notch on the +median process, the lesser proportion of the stalk included in the basal +enlargement, the more posterior position of the point of greatest width, +and the presence of a concavity in the posterior profile of the stalk in +dorsal view. These differences in the stalk may be owing to a difference +in age (my specimen perhaps being older). + +_Specimen examined_: One from 1 mi. NW Oho-ri, 6 M., Korea, 60438. + + +Phenacomys intermedius Merriam + +Figs. 7 and 8 + +Baculum: Stalk slender, greatest length (2.9 mm.) 2-1/4 to 2-1/2 times +greatest breadth, 4 times greatest depth; three well-developed ossified +processes, median one almost 1/2 length of stalk, curved, broad basally +and slightly larger in all dimensions than either lateral process; +lateral processes flattened distally, curved; base of stalk well +developed, basal tuberosities medially confluent or separated by medial +emargination, posterolateral faces flattened or rough; emarginations in +the four adults examined; posterior profile in dorsal view bluntly +pointed or flattened except for emargination posterially, abruptly curved +at point of greatest width; shaft arising broadly from distal side of +base of stalk; in end-view hour-glass shaped, medial constriction +pronounced, both dorsal and ventral concavities deep; shaft having +relatively straight but distally convergent sides; at mid-point of stalk, +1 to 1-1/2 times as wide as deep; tip bluntly rounded, or slightly +inflated. + +The specimens from Quebec differ from the one from Wyoming in smaller +size, relatively smaller lateral digital processes, larger more medial +basal emargination, and slender shafts. The baculum of _Phenacomys +intermedius_ differs much from that of _Phenacomys longicaudus_, +described by Hamilton (1946:381) and by Dearden (1958:547). Dearden +states that the three bacula examined by him of _Phenacomys longicaudus_ +differ markedly from the specimen described by Hamilton. It seems to me +that in major features the resemblance is greater between the specimens +of _Phenacomys longicaudus_ examined by these two authors than between +their specimens and specimens of other microtines, including _Phenacomys +intermedius_. Neither Hamilton nor Dearden record the exact localities of +capture, the collections in which the specimens are deposited, or the +catalogue numbers of specimens. Consequently verification of +identifications and observations is difficult. + +_Specimens examined_: Five, of two subspecies; _P. intermedius +intermedius_, 5.4 mi. S Moran, Teton Co., Wyoming, 3-C-309, collection of +W. B. Quay; _P. intermedius celatus_, four (including one immature +specimen) from Authiernord, Abitibi-ouest Co., Quebec, specimens in +collection of Bristol Foster designated by numbers 2041-2044 of S. +Anderson's field catalogue. Smith and Foster (1957:107) were of the view +that _Phenacomys ungava_ (including the above specimens from Quebec) may +be specifically distinct from _Phenacomys intermedius_. + + +Ondatra zibethicus (Linnaeus) + +Not figured + +Baculum: In the single specimen examined, less mature than that figured +by Hamilton (1946:384), the digitate processes are cartilaginous, the +basal tuberosities are less well developed, and the shaft is slenderer +throughout. The cartilaginous processes are of the same proportions as +ossified processes in the figure mentioned. The shaft is also convex +ventrally in lateral profile. The view of the side here considered to be +anatomically the ventral side (adjacent to the urethra) is labelled +dorsal view in Hamilton's specimen. + +_Specimen examined_: One, from Reserve, Brown Co., Kansas, 72405. + + +Microtus (Herpetomys) guatemalensis Merriam + +Figs. 42 and 43 + +Baculum: Stalk moderately elongate, greatest length (3.5 mm.) 2-1/3 times +greatest breadth, spatulate, flattened throughout, greatest thickness 1/3 +millimeter; three ossified processes; median process having three +cornered base, curved dorsally, wider than high, 1/4 to 1/5 greatest +length of stalk; each lateral process bent at middle, as long as median +process, compressed laterally; base of stalk curved dorsally, +tuberosities marginal, hence narrow, lateral excavations of tuberous +margin not confluent medially; in end-view ventral concavity broad, no +dorsal concavity, medial constriction but slightly less than greatest +thickness (not depth); shaft wider than high throughout, at mid-point +more than 3 times as wide as high; tip of shaft slightly inflated both +laterally and dorsoventrally; lateral profile gradually sloping +anteriorly from widest point of stalk. + +Specimen number 65921 (Fig. 43) differs from number 65895 (Fig. 42) +described above. Terminus of shaft of number 65921 has lateral lobes from +which arise lateral cartilaginous processes; median terminal ossification +irregular in shape, smaller, imbedded in terminally bilobate cartilage. +In the spatulate flattened stalk these two specimens are much alike. An +immature specimen, number 65908, is smaller (length of stalk 2.6 mm.) +also flattened and spatulate, has the terminal processes cartilaginous, +the lateral processes bent medially, and proportions as in the adult. + +The baculum shows no noteworthy resemblance to that of any other species +of North American _Microtus_; on the other hand the differences between +_M. guatemalensis_ and some other species are no greater than the +differences between certain species included in the subgenus _Microtus_. +The baculum neither strengthens nor weakens the case for subgeneric rank +for _M. (Herpetomys) guatemalensis_. + +_Specimens examined_: Three from Guatemala; 65895 (2 mi. S San Juan +Ixcoy), 65908, (3-1/2 mi. SW San Juan Ixcoy), 65921 (10 mi. E, 4 mi. S +Totonicapan). + + +Microtus (Arvicola) richardsoni (DeKay) + +Figs. 38 and 39 + +Baculum: Stalk broad, greatest length (3.7 to 4.3 mm.) 1-1/2 times +greatest breadth, relatively flattened, greatest depth 1/3 greatest +breadth; single median ossified process, in smaller of two specimens this +ossification incomplete and of unusual shape (Fig. 39); length of stalk 4 +times length of median process; concavities of basal tuberosities +medially confluent, constriction less than 1/2 greatest depth; widest +point of shaft less than 1/4 length of shaft from posteriormost point; +shaft wider than high except at distal end that is inflated dorsally and +sometimes laterally; both ventral and dorsal concavities of base of stalk +broad and moderately deep; posterior profile in dorsal view evenly +rounded or having marginal notch. + +In the absence of ossified lateral processes my two specimens differ from +bacula of _Microtus (Arvicola) terrestris_ figured by Didier (1943:79, +1954:245, 247, 248) and by Ognev (1950:591). The median process relative +to the size of the shaft is smaller, and the shaft relative to its length +is wider in _M. richardsoni_ than in _M. terrestris_. The stalk of _M. +(Arvicola) amphibius_ figured by Didier is like that of _M. richardsoni_ +in its greater breadth and median notch on posterior border. + +The relationship of the New World water rat, _M. richardsoni_, to the Old +World water rats (genus _Arvicola_ of some European authors) is +uncertain. Miller (1896:66) placed all of them in the subgenus +_Arvicola_. Subsequent authors, stressing differences in the teeth, have +placed _M. richardsoni_ in the subgenus _Aulacomys_ of Rhoads. Zimmerman +(1955) has shown that teeth in some _Arvicola_ approach the more complex +pattern of _M. richardsoni_. He argues also that _Arvicola_ is +generically distinct from _Microtus_ on the grounds that the two groups +have separate origins, _Arvicola_ having descended from the genus +_Mimomys_ and _Microtus_ from some other group of microtines. This +argument also was advanced by Hinton (1926:47-48). Pending further +studies of the possible polyphyletic origin of other subgenera of the +genus _Microtus_, I refer both _M. richardsoni_ and _M. terrestris_ to +the subgenus _Arvicola_. + +The evidence afforded by the bacula available is not conclusive as to +relations of Old World and New World water rats. No general agreement on +the number of species in this Palaearctic group has been reached, and +bacula of only three or four of the numerous Old World subspecies have +been figured. I have examined none. + +_Specimens examined_: Two, from Wyoming; 42454 (31 mi. N Pinedale, 8025 +ft., Sublette Co.), 37903 (23-1/2 mi. S, 5 mi. W Lander, 8600 ft., +Fremont Co.). + + +Microtus (Chilotus) oregoni (Bachman) + +Fig. 45 + +Baculum: Stalk broad, greatest length (2.2 mm.) 1-3/4 times greatest +breadth, 3-1/2 times greatest depth; three well-developed ossified +processes; median process 2/5 length of stalk, rounded or tapered +terminally, proximal end opposed to tip of stalk and flattened obliquely; +lateral processes 2/3 length of median process, deeper than wide, curved; +tuberosities of stalk well developed, confluent medially, visible in +dorsal view; in end-view dorsal concavity narrow, moderately deep, +rounded, ventral concavity wide, deep, flattened; base wider ventrally +than dorsally; shaft tapering more or less uniformly, terminally +inflated. + +In the relative sizes, to each other and to the stalk, of the three +digitate ossifications _M. oregoni_ resembles closely the Old World +representative of the same subgenus, _M. (Chilotus) socialis_, as figured +by Argyropulo (1933b:181). In _M. oregoni_ the greatest width of the +baculum is more proximal on the stalk than in the _M. socialis_ figured +by Argyropulo but closely resembles the baculum of the _M. socialis_ +figured by Didier (1954:242). In possessing a shallow emargination in the +base of the stalk and in possessing a median process that is smaller than +the lateral processes, _M. socialis_, as figured by Didier, differs from +_M. oregoni_. The baculum figured by Argyropulo (_loc. cit._) of +_Sumeriomys colchicus schidlovskii_ [ = _Microtus (Chilotus) socialis +schidlovskii_ according to Ognev, 1950:392] differs from other _Chilotus_ +that have been studied in having an unusually elongate median process and +a more distal placement of the widest part of the stalk. + +_Specimens examined_: Three, of the subspecies _M. oregoni oregoni_, from +5 mi. N Orick, Humboldt Co., California, 3-C-248, collection of W. B. +Quay; from Mary's Peak, Benton Co., Oregon, 66, collection of F. W. +Sturges; and from Sec. 3, T. 11S, R. 5W, Benton Co., Oregon, 79183. + + +Microtus (Stenocranius) gregalis (Pallas) + +Fig. 34 + +Baculum: Length of stalk (2.4 mm.) 1-3/4, times greatest breadth, 4-1/3 +times greatest depth; median ossified process well developed, more than +1/3 length of stalk, higher than wide, slightly bowed, closely appressed +to terminus of shaft; basal tuberosities of stalk moderately developed, +confluent medially, posterior profile of medial apex rounded in dorsal +view, lateral indentations present, hence trilobate outline; in proximal +end-view base wider ventrally, ventral concavity broader than dorsal +concavity but of equal depth, medial constriction 2/3 greatest depth; +shaft slender in distal part, inflated terminally, and wider than high at +mid-point of stalk; lateral profile a smooth slope of gradually +decreasing curvature from point of greatest width to near distal end. + +The baculum of this species figured by Ognev (1950:461) differs in having +lateral ossified processes, and a more rounded base of the stalk. +Resemblance to the New World _Stenocranius_ is discussed below. + +_Specimen examined_: One from "Eastern Europe," 8059. + + +Microtus (Stenocranius) miurus Osgood + +Figs. 32 and 33 + +Baculum: Length of stalk (2.8 mm.) 1-1/2 times greatest breadth, 3-1/2 +times greatest depth; median process ossified, 2/5 to 3/5 length of +stalk, laterally compressed, sometimes arched in dorsoventral plane; +lateral processes cartilaginous, slender; basal tuberosities well +developed, averaging less enlarged than shown in Figure 32, but more +angular in lateral outline than shown in Figure 33; tuberosities +confluent posteriorly; posterior profile smoothly rounded to trilobate, +curvature at point of greatest breadth usually acute; in proximal +end-view base wider dorsally, deep dorsal concavity, shallow ventral +concavity, medial constriction 3/5 of greatest depth; shaft slender +anteriorly, at mid-point of stalk twice as wide as high, at tip higher +than wide, laterally inflated; lateral profile in most specimens abruptly +curved anterior to point of greatest breadth. + +The single specimen of the Old World _M. (Stenocranius) gregalis_ +examined resembles the New World _M. (Stenocranius) miurus_ in the +angular lateral profile at the point of greatest breadth of the stalk, +slender shaft in comparison to broad base of stalk, and presence of a +single well-developed laterally compressed median process. The base of +the stalk in the baculum of _M. gregalis_ is less well developed and +smaller than in the baculum of _M. miurus_. + +_Specimens examined_: Nine, all of the subspecies _Microtus miurus +muriei_, from the Brooks Range, Alaska; 51077 (Lake Schrader, 145 deg.09'50", +69 deg.24'28", 2900 ft., Romanzof Mts.); 51151, 51152, 51154, 51164, 51166, +51169 (last 6 from Wahoo Lake, 69 deg.08', 146 deg.58', 2350 ft.); 51210, 51213 +(last 2 from Porcupine Lake, 68 deg.51'57", 146 deg.29'50", 3140 ft.). + + +Microtus (Chionomys) nivalis Martins + +Fig. 47 + +Baculum: Greatest length of stalk (2.7 mm.) 2-1/4 times greatest breadth, +4-1/2 times greatest depth; three digitate processes, lateral processes +mostly cartilaginous in single adult examined; median process well +ossified, approximately 1/3 length of stalk, basally notched, not arched, +laterally compressed distally; base of stalk broad and flat, basal +tuberosities well developed, separate; posterior profile in dorsal view +rounded, convex except for medial notch separating tuberosities; dorsal +and ventral concavities deep, broad, equal; medial constriction less than +1/2 greatest depth; in dorsal view shaft tapering gradually from widest +point, terminally rounded; at mid-point of stalk almost twice as wide as +high. + +In the elongate, largely cartilaginous lateral processes of the baculum, +the specimen described above resembles _M. longicaudus_. The size of the +median process in comparison to the size of the stalk is also the same. +The lateral processes have larger ossifications and the base of the stalk +is more robust in _M. longicaudus_ than in _M. nivalis_. + +The well ossified lateral processes and enlarged base of Didier's +(1954:240) specimen suggest that it is of a more mature individual than +the one described above. These specimens of _M. nivalis_, as well as the +specimens of _M. longicaudus_, exhibit dorso-ventral flattening of the +mid-part of the base of the stalk. + +The baculum of a specimen from Switzerland is weakly developed, of small +size (shaft 2.0 mm. in length), slender, thin, spatulate, and terminally +inflated. Digital processes were not observed, perhaps owing to excessive +maceration in preparation. The general appearance of the baculum is that +of an immature individual, although the animal was not small (165 mm. +total length in preservative). + +_Specimens examined_: Two _Microtus nivalis nivalis_; Zermatt, Valais, +Switzerland, 67105; Wetterstein, Germany, 65127. + + +Microtus (Chionomys) longicaudus (Merriam) + +Fig. 48 + +Baculum: Base of stalk well developed, greatest length (3 mm.) 1-3/4 +times greatest breadth, 3-2/3 times greatest depth; three ossified +processes; base of median process rounded; median process slightly curved +in dorsoventral plane, in length almost 1/3 greatest length of stalk; +ossifications in lateral processes variable in size, frequently widely +separated from shaft by cartilage, rarely as large as median +ossification; basal tuberosities usually well-developed, medially +confluent; profile of base in dorsal view trilobate or irregularly convex +throughout; constriction 1/2 greatest depth; shaft relatively straight or +slightly bowed ventrally or dorsally, shaft at mid-point of stalk wider +than high; tip of shaft laterally inflated; widest point of stalk +approximately 1/4 length of stalk from proximal end; lateral profile in +dorsal view tapers gradually onto shaft anteriorly from point of greatest +width of stalk; shaft variable, from slender terminally and nearly +parallel sided (Fig. 48), to broad distally and tapered. + +In many of the features that distinguish _M. longicaudus_ (and the +closely related insular species _M. coronarius_) from other North +American _Microtus_, _longicaudus_ resembles the Old World species of the +subgenus _Chionomys_ (that is to say, _M. nivalis_, _M. gud_, and _M. +roberti_). These features are medium size, long tail, grayish color, +montane habitat, relatively short molar tooth-row, moderate sized and +unconstricted incisive foramen, relatively decurved upper incisors, +elongate nasals, relatively broad interorbital region without +well-developed median ridge, and similar chromosomes (Matthey, 1955:178). +For these reasons I am here referring _Microtus longicaudus_ to the +subgenus _Chionomys_; previously it has not been referred to that +subgenus. + +_Specimens examined_: Six, of three subspecies; _Microtus longicaudus +littoralis_, Sullivan Island, Alaska, 42972, 42969; _M. l. mordax_, 3/4 +mi. N, 2 mi. W Allenspark, 8400 ft., Boulder Co., Colorado, 50335, 76829; +_M. l. sierrae_, Crane Flat, Mariposa Co., California, 50252, 50253. + + +Microtus arvalis (Pallas) + +Fig. 22 + +Baculum: In the single specimen examined, stalk small, greatest length +(2.3 mm.) 2-1/3 times greatest width, almost 6 times greatest depth, +flattened proximally; three well-developed digitate processes, the median +one ossified, the lateral processes cartilaginous; median ossification +laterally compressed and decurved at tip, bilobate at base; basal +tuberosities of stalk weakly developed, medially confluent; posterior +profile in dorsal view evenly rounded; ventral concavity deeper and +narrower than dorsal concavity, but both comparatively shallow; medial +constriction 2/3 greatest depth; shaft straight, at mid-point twice as +wide as deep; lateral profile tapering from greatest width gradually to +parallel sides of distal third of stalk. + +From the baculum of _Microtus arvalis_ figured by Ognev (1950:173), and +from the baculum figured by Didier (1954:238) my specimen differs in the +absence of lateral ossifications in the digitate processes, smaller and +slenderer median ossification, and weaker base. These differences in part +may be owing to a difference in age, my specimen being the less mature. + +_Specimen examined_: One from Vidy, Switzerland, 67101. + + +Microtus orcadensis Millais + +Fig. 24 + +Baculum: In the one specimen examined, stalk broad, greatest length (2.6 +mm.) 1-1/2 times greatest breadth, 3-1/2 times greatest depth; three +digitate processes ossified; median process relatively broad, in length +more than 1/2 length of stalk, triangular in dorsal view, with small +spurs posterolaterally, middorsal ridge posteriorly; lateral +ossifications slightly curved, slenderer, less than 1/2 depth and less +than 1/2 transverse thickness of median process; basal tuberosities +well-developed, confluent medially; in end-view base wider dorsally than +ventrally, dorsal concavity broader and more abruptly curved at mid-point +than ventral concavity; constriction 1/2 greatest depth; posterior +profile in dorsal view notched, setting off a posterior shelf; stalk +including shaft wider than deep throughout, at mid-point width twice +depth; lateral profile abruptly curved anterior to point of greatest +width, sides of shaft tapering gradually anteriorly to rounded uninflated +tip. + +The baculum of this insular species, placed in the "_arvalis_" group by +Ellerman (1941:595), resembles the baculum of both _Microtus agrestis_ +and _Microtus guentheri_ more than it resembles the baculum of _Microtus +arvalis_. Similarities in the chromosomes of _M. arvalis_ and _M. +orcadensis_ were noted by Matthey (1953:254, 279), who was of the opinion +that _M. orcadensis_ is an insular derivative of the _arvalis_-group. + +_Specimen examined_: One from the Orkney Islands, 67106. + + +Microtus guentheri Danford and Alston + +Fig. 23 + +Baculum: In the one specimen examined, stalk broad, greatest length (2.9 +mm.) 1-1/2 times greatest breadth, 3-1/2 times greatest depth; three +digitate processes ossified; median process slightly less than 1/2 length +of stalk, broad, dorsally curved; curved lateral ossifications shorter +and more slender than median ossification; basal tuberosities well +developed, angular, confluent across posterior border of projecting +shelf; in end-view tuberosities projecting ventrolaterally from central +shelf; dorsal surface at medial constriction flat, ventral surface +broadly and deeply concave; posterior profile in dorsal view trilobate, +central lobe formed by posteriorly flattened shelf, surface of attachment +visible only on lateral lobes; at mid-point stalk almost twice as wide as +deep, depth of shaft greater than width proximal to inflated terminus. + +_Specimen examined_: One from Palestine, 67104. + + +Microtus fortis Buechner + +Fig. 25 + +Baculum: Stalk large, greatest length (3.8 mm.) 1-4/5 times greatest +breadth, 4-1/2 times greatest depth; three digitate processes ossified; +median ossification almost 1/3 length of stalk; lateral ossifications +slender, smaller than median ossification; posterior profile of stalk in +dorsal view trilobate, basal tuberosities well developed, confluent +medially; in end-view dorsal concavity broader and deeper than ventral +concavity; medial constriction pronounced (less than 1/2 greatest depth); +lateral profile at widest point of stalk convex, becoming abruptly +concave as the flange of the basal tuberosities grades into the shaft, +then gradually converging to narrowest point 1/3 of length of stalk from +the terminus; stalk wider than deep in proximal 2/3, circular in cross +section in terminal 1/3, slight terminal inflation. + +A specimen figured by Ognev (1950:297) has the same general proportions, +slender lateral processes, and proximal placement of the point of +greatest breadth. + +_Specimens examined_: Two from Chipo-ri, Korea, 60443, 63841. + + +Microtus montanus (Peale) + +Figs. 19, 20 and 21 + +Baculum: Stalk broad, greatest length (varying with subspecies from 2.3 +to 3.1 mm.) 1-1/2 to 1-3/4 times greatest breadth, 3-1/3 to 4-1/3 times +greatest depth; three ossified processes, median one largest, more than +twice as wide and as deep as shorter, slenderer, lateral processes; +median process laterally compressed distally except in one specimen in +which moderately inflated distally, proximally enlarged in some specimens +(Fig. 21) and 1/3 to 2/5 length of stalk; base broad, posterior profile +in dorsal view evenly convex throughout, at widest point of stalk +abruptly incurved; basal tuberosities moderately to strongly developed, +medially confluent; in end-view base wider ventrally than dorsally, +dorsal concavity slightly to much deeper than the nearly flattened +ventral concavity; medial constriction 2/3 to 4/5 of greatest depth; +shaft relatively slender, at mid-point of stalk slightly wider than high +and 1/4 as wide as base of stalk, terminally rounded or slightly +inflated; lateral profile in dorsal view a gradual curve from point of +greatest width anteriorly onto shaft. + +The different subspecies figured show the essential characteristics of +the species, differing primarily in size. + +_Specimens examined_: Fourteen, of three subspecies; _Microtus montanus +amosus_, 1/2 mi. E Soldier Summit, Wasatch Co., Utah, 62241; _M. montanus +fusus_, La Manga Pass, Conejos Co., Colorado, 42164; 5 mi. N, 26 mi. W +Saguache, 9500 ft., Saguache Co., Colorado, 42307, 42315; 5 mi. N, 27 mi. +W Saguache, 9350 ft., Saguache Co., Colorado, 42308; 5 mi. N, 28 mi. W +Saguache, 9325 ft., Saguache Co., Colorado, 42309; 5 mi. S, 24 mi. W +Antonito, 9600 ft., Conejos Co., Colorado, 42327, 42330; Prater Canyon, +Mesa Verde National Park, Montezuma Co., Colorado, 69456, 69457, 69463; +_Microtus montanus nanus_, 2 mi. N, 2 mi. W Pocatello, Bannock Co., +Idaho, 57470, 57472; 3/4 mi. N, 2 mi. W Allenspark, 8400 ft., Boulder +Co., Colorado, 50330. + + +Microtus townsendii (Bachman) + +Fig. 41 + +Baculum: Stalk broad, greatest length (3.0 mm.) 1-1/2 times greatest +breadth, 4-1/2 times greatest depth; three ossified processes, median one +largest, deeper and more than twice as wide as curved, shorter, +compressed lateral processes and more than 2/5 as long as stalk; base +broad, in dorsal view posterior profile trilobate, basal tuberosities +visible; basal tuberosities well developed, medially confluent; in +end-view base wider ventrally than dorsally, dorsal concavity deeper than +ventral concavity; medial constriction 3/5 of greatest depth; shaft +broad, at mid-point more than twice as wide as high and 1/3 as wide as +base of stalk, terminally rounded. + +_Specimens examined_: Three, all _M. t. townsendii_; Fort Lewis, Pierce +Co., Washington, 57998, subadult; Sec. 33, T. 11S, R. 5W, Benton Co., +Oregon, 79186; Sec. 5, T. 12S, R. 4W, Benton Co., Oregon, 79188. + + +Microtus oeconomus (Pallas) + +Fig. 44 + +Baculum: Stalk broad and flattened, greatest length (3.5 mm.) 1-2/3 to 2 +times greatest width, 4 to 5-1/2 times greatest depth; three ossified +processes, median one largest, lateral processes slender, relatively +small; length of median process 3/8 length of stalk; median process +decurved, dorsoventrally flattened in some specimens, widened at base; +attachment of processes to shaft displaced ventrally; base of stalk +widened, posterior profile in dorsal view usually trilobate, in a few +cases rounded, median lobe forming posterior shelf, lateral lobes +dorsally raised and forming margins of lateral tuberosities; in end-view +thickness frequently more or less uniform throughout central part, broad +depression dorsally, ventral concavity narrower and shallower (as +figured); base, and occasionally shaft, flattened, width at mid-point of +stalk 2 to 3 times depth, narrowest point posterior to terminal inflation +of shaft in terminal 1/3 of shaft. + +The baculum of _M. oeconomus_ (Old World) figured by Ognev (1950:257) +resembles but exceeds that of _M. oeconomus_ (New World) in the +relatively large median process and slender lateral processes, but +differs noticeably in the presence of a deep median notch in the base of +the stalk. A specimen from Hungary is intermediate between Ognev's +specimen and those from the New World in both size of median process and +size of lateral processes, and has an unnotched base resembling that in +Figure 44. + +_Specimens examined_: Ten, of three subspecies; _M. oeconomus gilmorei_, +Umiat, Alaska, 51354, 51361, 51399, 51408; Lake Schrader, Brooks Range, +Alaska, 51422; _M. o. macfarlani_, 5 mi. NNE Gulkana, Alaska, 43039, +43041; 20 mi. NE Anchorage, Alaska, 43044; Kelsall Lake, British +Columbia, 43048; _M. o. mehelyi_, Kisbalatan, Hungary, 75159. + + +Microtus mexicanus (Saussure) + +Figs. 35 and 36 + +Baculum: Stalk attenuate, greatest breadth relatively near proximal end; +greatest length (3.1 to 3.4 mm.) more or less twice greatest breadth, 4 +to 5 times greatest depth; usually a single process ossified; lateral +processes relatively small, cartilaginous or (in three specimens, 63094, +69453, 68019) with small ossifications; median process relatively small, +sometimes appressed to tip of shaft, in length less than 1/4 length of +stalk; posterior profile in dorsal view rounded, flattened posteriorly, +or in some specimens trilobate with angular edges; in end-view relative +depths of dorsal and ventral concavities variable, dorsal usually deeper +than ventral; distal end of stalk frequently bowed dorsally; shaft +slender distally, sometimes slightly inflated terminally, or (in one +specimen, 63085) near tip small lateral projections that are perhaps +fused lateral ossifications; lateral profile in dorsal view a gradual +slope anteriorly from point of greatest width to slender tip. + +_Specimens examined_: Thirteen, of four subspecies; _Microtus mexicanus +mexicanus_, Las Vigas, Veracruz, 30692; Nevada de Toluca, Mexico, 63101; +Valle de Bravo, Mexico, 63094; _Microtus mexicanus mogollonensis_, Mt. +Taylor, Valencia Co., New Mexico, 63298, 76830; Park Well, Mesa Verde +National Park, Montezuma Co., Colorado, 69448, 69453; Upper Nutria, +McKinley Co., New Mexico, 69997, 70000; _Microtus mexicanus phaeus_, +Sierra Patamba, 9000 ft., Michoacan, 63085; _Microtus mexicanus +subsimus_, 2 mi. E Mesa de Tablas, Coahuila, 58916; 13 mi. E San Antonio +de las Alazanas, Coahuila, 68019, 68021. + + +Microtus californicus (Peale) + +Fig. 37 + +Baculum: Stalk elongate, greatest length (3.0 mm.) 2-1/3 times greatest +breadth, 4-1/2 times greatest depth; median process ossified, 1/4 length +of stalk, basally broadened, flattened and shallowly grooved ventrally to +fit tip of shaft, to which the process is closely appressed; lateral +processes cartilaginous; ends of stalk bowed upwardly; posterior profile +of base of stalk rounded or slightly trilobate if posterolateral +concavities form in tuberosities; moderate development of tuberosities, +in end-view dorsal concavity slightly deeper and narrower than ventral +concavity, both comparatively shallow, median constriction 4/5 greatest +depth; shaft curved, more or less terete at mid-point of stalk, +terminally inflated dorsally; lateral profile in dorsal view gradually +curved from point of greatest width anteriorly onto shaft. + +_Specimens examined_: Two, of two subspecies; _Microtus californicus +californicus_, 1 mi. NE Berkeley, in Contra Costa Co., California, 76828; +_Microtus californicus mohavensis_, 1/2 mi. SE Victorville, San +Bernardino Co., California, 63745. + + +Microtus pennsylvanicus (Ord) + +Figs. 14, 15, 16 and 17 + +Baculum: Stalk heavy, broad, greatest length (2.2 to 3.0 mm.) 1-1/3 to +1-2/3 times greatest breadth, up to 3-3/4 times greatest depth; three +ossified processes, median one largest, usually not twice so deep as +lateral ossifications; median process usually distinctly widened basally, +in length approximately 1/2 length of stalk; base broad, frequently +angular laterally and basally, sometimes bilobate; basal tuberosities +well developed, medially confluent; in end-view more or less uniformly +biconvex or ventral surface more flattened than dorsal surface, medial +constriction 1/2 to 2/3 greatest depth; shaft relatively heavy, at +mid-point stalk almost twice as wide as deep and 1/3 as wide as base of +stalk; shaft terminally rounded and sometimes slightly inflated; lateral +profile in dorsal view abruptly or gradually curved anterior to point of +greatest width and then gradually curved anteriorly. + +Specimens examined averaged slightly smaller and were more variable than +those described by Hamilton (1946:382). The greater variation may be in +part geographic, as five subspecies are represented. Lateral processes +are the last to ossify. One specimen (75082) with well-ossified median +process lacks any lateral ossification. Four bacula of _M. +pennsylvanicus_ (locality not specified) studied by Dearden (1958:547) +agree in general with the description above. + +One specimen shows a break, perhaps resulting from injury, in the shaft +(Fig. 14). One specimen has a posteromedian spine on the median digital +ossification (Fig. 16). Comparison with _M. agrestis_ is included with +the description of _M. agrestis_. + +_Specimens examined_: Thirteen, of six subspecies; _Microtus +pennsylvanicus alcorni_, 20 mi. NE Anchorage, Alaska, 43043; _Microtus +pennsylvanicus finitus_, Laird, Yuma Co., Colorado, 68544; _Microtus +pennsylvanicus modestus_, 5 mi. N, 26 mi. W Saguache, 9500 ft., Saguache +Co., Colorado, 42306; 3 mi. N, 16 mi. W Saguache, 8500 ft., Saguache Co., +Colorado, 42416, 42417, 42418; 1 mi. S, 2 mi. E Eagle Nest, 8100 ft., +Colfax Co., New Mexico, 42430, 42439; _Microtus pennsylvanicus +pennsylvanicus_, 2 mi. S, 3 mi. E Ft. Thompson, 1370 ft., Buffalo Co., +South Dakota, 42379; Vermillion, Clay Co., South Dakota, 37070; _Microtus +pennsylvanicus pullatus_, 12 mi. S, 5 mi. E Butte, Silver Bow Co., +Montana, 57501, 57503; _Microtus pennsylvanicus uligocola_, Muir Springs, +2 mi. N, 2-1/2 mi. W Ft. Morgan, Morgan Co., Colorado, 75082. + + +Microtus agrestis (Linnaeus) + +Fig. 18 + +Baculum: Greatest length of stalk (2.9 mm.) twice greatest breadth, 4-1/2 +times greatest depth; stalk well developed, shaft not flattened +dorsoventrally; large median ossified process, minute lateral +ossifications in single specimen examined; length of stalk 2-1/2 times +length of median ossification which is higher than wide, slightly +decurved, sagittate in dorsal view, with three-cornered base; basal +tuberosities of stalk moderately well developed, medially joined; +posterior profile in dorsal view evenly rounded; ventral concavity +broader than, but of comparable depth to, dorsal concavity in end-view, +base of stalk wider ventrally, constriction 3/4 greatest depth; at +mid-point of stalk shaft is but slightly wider than high; pronounced +terminal inflation of shaft; lateral profile in dorsal view sloping +abruptly from widest point of stalk anteriorly onto stalk which then +tapers more gradually to terminal inflation. + +From the baculum of its New World counterpart, namely _Microtus +pennsylvanicus_, my specimen of _Microtus agrestis_ and the specimen +figured by Didier (1954:239) differ in their minute lateral processes, +relatively larger median processes, and more elongate, less +dorsoventrally flattened shafts. + +The specimen of _M. agrestis_ figured by Ognev (1950:320), in dorsal view +has lateral concavities producing a somewhat trilobate outline in the +base of the stalk, and the lateral processes are well developed; the +median process is larger and bulbous, wider distally than proximally. +Without larger numbers of bacula of _M. agrestis_ I am unable to +reconcile these differences. The differences between _M. agrestis_ and +_M. pennsylvanicus_ seem comparable to the differences between some other +species of _Microtus_. + +_Specimen examined_: One, from Gryon, Switzerland, 67102. + + +Microtus (Pedomys) ochrogaster (Wagner) + +Fig. 31 + +Baculum: Stalk broad, greatest length (3.2-4.0 mm.) 1-2/3 to 2 times +greatest breadth, 2-1/2 to 4 times greatest depth; median process +ossified, relatively small, less than 3/10 length of stalk; lateral +processes arising from subterminal part of stalk, cartilaginous or with +small ossifications; posterior profile in dorsal view broadly rounded or +slightly angular, widest point of stalk 1/6 to 1/4 the length of stalk +from base; basal tuberosities well developed and medially confluent, in +end-view dorsally convex, or at least less deeply concave than ventrally; +shaft straight, base bent ventrally or more commonly dorsally; at +mid-point of stalk wider than high, often twice as wide as high; viewed +from above, lateral profile from point of greatest breadth to middle of +shaft a gradual sigmoid curve; slight terminal inflation of shaft. + +_Specimens examined_: Forty-one, of three subspecies; _Microtus +ochrogaster haydeni_, Muir Springs, 2 mi. N, 2-1/2 mi. W Ft. Morgan, +Morgan Co., Colorado, 74995, 74998, 74999, 75002; 1 mi. W Laird, Yuma +Co., Colorado, 57304, 76833; 2 mi. N, 2 mi. W Haigler, Dundy Co., +Nebraska, 75016; 2 mi. S Franklin, Franklin Co., Nebraska, 75043, 75044; +Atwood, Rawlins Co., Kansas, 75020, 75023, 75025, 75027, 75028; 1 mi. N, +2 mi. E Oberlin, Decatur Co., Kansas, 75030, 75032, 75034, 75035, 75036; +1-1/2 mi. N, 1/4 mi. E Norton, Norton Co., Kansas, 68327; 1 mi. SW +Norton, Norton Co., Kansas, 75037; 2 mi. S, 1 mi. W Norton, Norton Co., +Kansas, 75038; _M. ochrogaster ochrogaster_, Rydal, Republic Co., Kansas, +75047-75053, 75060, 75062, 75063, 75066, 75070, 75071, 75073; 1 mi. N, 1 +mi. W Holton, Jackson Co., Kansas, 75077; 2 mi. W Court House, Lawrence, +Douglas Co., Kansas, 76832; Univ. Kansas Natural History Reservation, +Douglas Co., Kansas, 68536; _M. ochrogaster taylori_, Meade County State +Park, Kansas, 68539, 68542. + + +Microtus (Pitymys) pinetorum (LeConte) + +Figs. 27 and 28 + +Baculum: Stalk broad, greatest length (2.5 to 2.7 mm.) 1-2/3 times +greatest breadth, 4 times greatest depth; median process ossified, size +small, 1/5 length of stalk, higher than wide, having small anterodorsal +prominence in both specimens examined; lateral processes cartilaginous, +relatively small, displaced posteriorly, attenuate; posterior margin in +dorsal view broadly rounded, or having blunt median apex, convex +throughout; basal tuberosities moderately well developed, medially +confluent, barely visible in dorsal view when mature; in end-view median +constriction 4/5 greatest depth, ventral concavity deeper than dorsal +concavity, both comparatively shallow; stalk at mid-point 1-1/2 times as +wide as deep; shaft relatively slender, bowed dorsally at tip, relatively +straight otherwise; lateral profile in dorsal view a gradual concave +slope from point of greatest width anteriorly to distal part of shaft. + +_Specimens examined_: Two, from Douglas Co., Kansas, 76834 (2 mi. N +Baldwin), 68545 (1 mi. NE Pleasant Grove). + + +Microtus (Pitymys) parvulus (Howell) + +Fig. 40 + +Baculum: Stalk broad, greatest length (2.4 mm. in specimen examined) +1-3/4 times greatest breadth, 4 times greatest depth; median process +ossified, size small, less than 1/4 length of stalk, wider than high, +terminally flattened; lateral processes cartilaginous, relatively small, +attenuate; posterior margin in dorsal view flattened, irregularly curved +with concavities medially and laterally; basal tuberosities well +developed, medially confluent; visible in dorsal view; in end-view median +constriction 2/3 greatest depth, ventral concavity well-formed, no dorsal +concavity; stalk at mid-point twice as wide as deep; shaft relatively +slender, bowed dorsally toward tip; in dorsal view lateral profile a +gradual concave slope from point of greatest width anteriorly to distal +part of shaft; tip of shaft enlarged. + +The baculum of _M. parvulus_ resembles that of _M. pinetorum_ more than +it resembles the baculum of any other microtine studied, differing +primarily in smaller size. + +_Specimen examined_: One, from 1 mi. W Micanopy, Alachua Co., Florida, +Univ. Florida No. 1508. + + +Microtus (Pitymys) quasiater (Coues) + +Figs. 29 and 30 + +Baculum: Stalk broad, greatest length (2.6-3.2 mm.) 1-1/3 to 1-2/3 times +greatest breadth, 3-1/3 to 3-2/3 times greatest depth; median process +ossified, with ventral depression, process 1/4 to 1/3 length of stalk, +appressed to tip of shaft, wider than high proximally, relatively broad +terminally; lateral processes cartilaginous, small, attenuate; posterior +profile of stalk in dorsal view broadly rounded, bilobate, or trilobate, +median lobe formed by posterior projection of dorsal shelf between +enlarged lateral tuberosities that form outer lobes, posterolateral faces +of these tuberosities visible in dorsal view of stalk; in end-view dorsal +surface slightly concave, ventral concavity broad and deep, median +constriction 1/2 greatest depth; shaft flattened except tip that is more +terete, and bowed dorsally; at mid-point, stalk twice as wide as high; +shaft relatively slender terminally, narrower than median ossification. + +The baculum of _M. quasiater_ is the largest and has the best developed +base and median process of the three American species of the subgenus +_Pitymys_. The three species closely resemble each other in basic form. + +_Specimens examined_: Five, all from Veracruz; Teocelo, 4500 ft., 30709, +30711; 4 km. N Tlapacoyan, 1700 ft., 24466; 5 km. N Jalapa, 4500 ft., +19869, 19878. + + +Microtus (Pitymys) fatioi (Mottaz) + +Fig. 26 + +The baculum of a single specimen (KU 67103) of _M. fatioi_ from Zermatt, +Valais, Switzerland, was examined. The baculum is immature, as evidenced +by its small size, slender stalk and absence of ossified processes, +therefore no characterization is included. + +The baculum of another Old World species of the subgenus _Pitymys_, _M. +pyrenaicus_ from France, figured and described by Didier (1954:242-243), +differs from all New World _Pitymys_ examined in processing ossified +lateral processes. + +The status of _Pitymys_, as a genus or as a subgenus, is uncertain. Hall +and Cockrum (1953:448) considered the North American _Pitymys_ and +_Pedomys_ as subgenera of _Microtus_. They did not state specifically the +basis for this point of view, but mention the fact that these two +subgenera (_Pitymys_ and _Pedomys_) closely resemble each other +cranially. These authors did not study nor comment upon the status of the +Old World _Pitymys_. It may be asked whether the Old World and New World +_Pitymys_ have developed as fossorial _Microtus_ independently, or from +an ancestor common to both groups and not common to any other _Microtus_. +Matthey (1955:202) found 62 chromosomes (2N) in both the New World +_Pitymys pinetorum_ and the Old World _Pitymys duodecimcostatus_. This +suggests, but does not prove, common ancestry. + + +Neofiber alleni True + +Fig. 49 + +Baculum: Stalk massive, greatest length (4.7 mm.) 1-3/4 times greatest +breadth, 4 times greatest depth; ossification in digitate processes +variable; in one (KU 27123) of two specimens examined lateral processes +ossified and median process unossified, as in two specimens examined by +Hamilton (1946:379) from "southern Florida"; in my other specimen (KU +27268) that is possibly more mature, median process ossified although +less deeply stained than lateral ossifications or stalk; posterior +profile in probable dorsal view roughly rounded; in end-view probable +dorsal concavity deep, ventral concavity broad but shallow, and with +center convex; median constriction 3/5 greatest depth; shaft heavy, least +depth 2/3 greatest depth of base; stalk, at mid-point, slightly wider +than deep and more than 1/3 width of base; lateral profile in dorsal view +sharply incurved distal to point of greatest breadth, shaft therefore +relatively distinct from basal part of stalk; slight subterminal +constriction; tip less reduced in the two specimens examined than in two +figured by Hamilton. In preparation, the tissues that make it possible to +distinguish with certainty the dorsal and ventral surfaces of the baculum +were removed in both specimens. + +_Specimens examined_: Two, of the subspecies _Neofiber alleni alleni_, 2 +mi. S Gainesville, Alachua Co., Florida, 27268; 1 mi. E Courtenay, +Merritt Island, Brevard Co., Florida, 27123. + + +Lagurus curtatus (Cope) + +Fig. 46 + +Baculum: Stalk slender, greatest length (2.5 mm.) 2 to 2-2/3 times +greatest breadth, 4 to 5 times greatest depth; three ossified processes; +median one more than 1/3 length of stalk, curved dorsally toward tip, +proximally flattened and having acute lateral angles in dorsal view, +wider than deep except in distal half; lateral processes smaller than +median one, slenderer, shorter, of approximately same depth, also curved +dorsally; base of stalk well developed, basal tuberosities medially +confluent, in part visible in dorsal view, in end-view wider ventrally +than dorsally, dorsal and ventral concavities of equal depth and both +wide, medial constriction 1/2 greatest depth; posterior profile in dorsal +view broadly bilobate; lateral profile with abrupt transition from basal +tuberosities to gradually converging, slightly curved sides of shaft; +shaft terminally inflated. + +Dearden (1958:543) described and figured the bacula of six subspecies of +_Lagurus curtatus_ and two Asiatic species, _Lagurus lagurus_ and +_Lagurus luteus_. He examined at least 34 specimens of _L. curtatus_ and +found geographic variation in size, breadth of shaft distally, and +proportions of digital ossifications to each other and to the stalk. The +description that I have given above pertains to _L. c. levidensis_. + +The baculum of the Asiatic _Lagurus (Lagurus) lagurus_ figured by Ognev +(1950:554) agrees with that of _Lagurus (Lemmiscus) curtatus_, described +here, in the relatively elongate shaft and slender stalk, the proportions +of the processes, and the well-formed and moderately enlarged base of the +stalk. The bacula of three _Lagurus lagurus_ examined by Dearden +(1958:545) were of older individuals than the specimen that Ognev figures +and differ from it and from bacula of _Lagurus curtatus_ (all subspecies) +in the unusual, almost heart shaped, median process, and in larger size. +_Lagurus luteus_ examined by Dearden (1958:545) differs from both +_Lagurus lagurus_ and _Lagurus curtatus_ in lacking lateral digital +ossifications and in having shorter median digital ossifications and +wider base of stalk. + +_Specimens examined_: Seven _Lagurus curtatus levidensis_ from Wyoming; 9 +mi. S Robertson, Uinta Co., 26045, 26053; 8 mi. S, 2-1/2 mi. E Robertson, +Uinta Co., 26049; Farson, Sweetwater Co., 37906; 16 mi. S, 11 mi. W +Waltman, Natrona Co., 42457; 32 mi. S, 22 mi. E Rock Springs, 42465, +42466. + +The following key to the bacula in some adult North American Microtinae +is intended to help point out some of the most important differences. It +should be noted that not all species can be keyed out on the basis of the +baculum. The most difficult group in this respect includes the species of +_Microtus_ that have small or no ossified lateral processes, especially +species of the subgenera _Pedomys_ and _Pitymys_, and the two species +_Microtus californicus_ and _Microtus mexicanus_ of the subgenus +_Microtus_. Another complicating factor is the variability of bacula +evident in some species even in the small samples available. It is to be +expected that additional specimens will show variations not yet observed. + + +KEY TO THE BACULA OF SOME NORTH AMERICAN MICROTINES + + 1. Length of lateral digital ossifications more than 1/3 breadth + of stalk 2 + + 1'. Length of lateral digital ossifications less than 1/3 breadth + of stalk or absent 15 + + 2. Size small (total length of baculum less than 5.5 mm.) 3 + + 2'. Size large (total length of baculum more than 5.5 mm.) 14 + + 3. Width at mid-point of stalk more than 1/3 greatest breadth of + stalk 4 + + 3'. Width at mid-point of stalk less than 1/3 greatest breadth of + stalk, 8 + + 4. Stalk, viewed from proximal end hour-glass shaped, and width + of stalk less than 1/2 length of stalk.... _Phenacomys + intermedius_, p. 197 + + 4'. Stalk not both hour-glass shaped when viewed from proximal + end, and with width less than 1/2 length of stalk 5 + + 5. Shaft thin basally, thickness less than 1/3 of greatest breadth 6 + + 5'. Shaft thick basally, thickness 1/3 or more of greatest breadth 7 + + 6. Stalk more or less straight, base not deflected. _Microtus + oeconomus_, p. 204 + + 6'. Stalk spatulate, and base deflected from axis of shaft.... + _Microtus guatemalensis_, p. 198 + + 7. Base enlarged, depth nearly 1/2 of breadth.... _Lemmus + trimucronatus_, p. 193 + + 7'. Base moderately enlarged, depth near 1/3 of breadth.... + _Microtus pennsylvanicus_, p. 206, or _Microtus townsendii_, p. 204 + + 8. Base hour-glass shaped as viewed from proximal end.... + _Phenacomys intermedius_, p. 197 + + 8'. Not so 9 + + 9. Lateral processes separated from tip of shaft by more than the + thickness of the lateral process 10 + + 9'. Lateral processes separated from tip of shaft by less than the + thickness of the lateral process 11 + + 10. Lateral processes more than 1/2 the width of median + process.... _Microtus longicaudus_, p. 201 + + 10'. Lateral processes slender, less than 1/2 the width of median + process.... _Microtus montanus_, p. 204 + + 11. Lateral ossifications equal in length to median + ossification.... _Clethrionomys_, p. 194 + + 11'. Lateral ossifications shorter than median ossification 12 + + 12. Size small, less than 3.4 mm. in total length.... + _Microtus oregoni_, p. 199 + + 12'. Size medium, more than 3.4 mm. in total length 13 + + 13. Greatest width of stalk at a point about 1/3 of length of + stalk from base.... _Microtus chrotorrhinus_ (Hamilton, 1946:382). + + 13'. Greatest width of stalk at a point less than 1/3 of length of + stalk from base.... _Lagurus curtatus_, p. 210 + + 14. Size of baculum larger, base more than 3 mm. wide, processes + all well developed.... _Ondatra zibethicus_, p. 198 + + 14'. Size of baculum smaller, base less than 3 mm. wide, processes + poorly developed in some animals.... _Neofiber alleni_, p. 209 + + 15. At least one digital ossification present 16 + + 15'. Digital ossifications not present.... _Dicrostonyx + groenlandicus_, p. 193 + + 16. Breadth of stalk at least 1/2 length of stalk 17 + + 16'. Breadth of stalk less than 1/2 length of stalk 19 + + 17. Length of stalk greater than 3.6 mm. and less than 1-1/2 + times its greatest breadth.... _Microtus richardsoni_, p. 199 + + 17'. Length of stalk usually less than 3.6 mm., or if more than + 3.6 mm. (up to 4.0 mm.) then length 1-1/2 times or more its + greatest breadth 18 + + 18. Median process attenuate distally in dorsal view, and + relatively long (more than twice its own breadth), 1/5 to 3/5 the + length of stalk; breadth of stalk usually 2/3 or more length of + stalk.... _Microtus miurus_, p. 200 + + 18'. Median process relatively blunt distally in dorsal view, + relatively short (usually less than 1/4 length of stalk), breadth + of stalk usually less than 2/3 length of stalk.... + _Pitymys_, p. 208, _Pedomys_, p. 207, or _Microtus mexicanus_, p. 205 + + 19. Distal processes small and firmly ankylosed to distal end of + shaft.... _Phenacomys longicaudus_, p. 197 + + 19'. Distal processes if present not firmly ankylosed to distal + end of shaft 20 + + 20. Dorsal concavity of base as viewed from proximal end usually + deeper than ventral concavity.... _Microtus mexicanus_, p. 205 + + 20'. Dorsal and ventral concavities of base equal in depth or + ventral one the deeper 21 + + 21. Total length of baculum more than 3.6 mm.... _Microtus + californicus_, p. 205 + + 21'. Total length of baculum less than 3.6 mm.... _Synaptomys + cooperi_, p. 194 + + + + +DISCUSSION + + +Owing to shortness of lower incisors and present geographic distribution +of the species, Hinton (1926:35) considered the Tribe Lemmi (lemmings) to +be more primitive than the Tribe Microti (voles). The surviving lemmings +are specialized in many features and therefore are considered as advanced +end-products of an evolutionary radiation of a primitive microtine stock, +of which all earlier stages are extinct. + +Hinton regarded _Dicrostonyx_ as the most primitive of the genera of +lemmings on account of its more complex molar teeth (complexity was +considered to be primitive), and on account of the presence of three +primitive longitudinal rows of tubercles in unworn molars. The other +three genera were arranged in order of increasing specialization as +follows: _Synaptomys_, _Myopus_, _Lemmus_. + +If the baculum tended to retain its primitive character while +specializations in the external anatomy developed, and if the above +arrangement is correct the most primitive bacula would be found in +_Dicrostonyx_ and in _Synaptomys_. The baculum in these two genera in +comparison to that in _Myopus_ (as figured by Ognev, 1948:512) and +_Lemmus_ has a slenderer stalk and smaller digital ossifications or none +at all. The baculum in the genera of lemmings increases in robustness and +the development of processes from _Dicrostonyx_, to _Synaptomys_, to +_Myopus_, to _Lemmus_--the same order outlined above for total of +specialization. The two extremes in this series are near the extremes of +variation in bacula to be found in all microtines. The baculum in +lemmings as a group cannot then be considered more primitive than in +voles as a group, although the voles are usually considered to be more +advanced. The situation in the voles, as we shall see, casts a different +light on the matter. + +The voles, Tribe Microti, were considered by Hinton (1926:40) to be more +advanced than the lemmings because the incisors of the voles are longer +and the root of their last lower molar is lingual to the root of the +incisor. Hinton thought also that the murine ancestors of microtines had +shorter incisors and that the backward extension of the incisors in the +voles is a more ancient feature than the hypsodonty of the molars. A +trend in the molar teeth has been toward greater hypsodonty. The voles in +which the molars are least hypsodont are thus considered primitive. These +include the living genera _Clethrionomys_, _Phenacomys_, _Ondatra_, +_Dolomys_, _Ellobius_, and _Prometheomys_. Therefore, the baculum, in +these assumedly primitive genera, would be expected to resemble the +baculum in the lemmings or at least the most primitive lemmings. This is +not the case. + +The bacula that I have examined of _Clethrionomys_ and _Phenacomys_ have +well-developed digital ossifications. In this they resemble the baculum +of the genus _Lemmus_, the most advanced genus of lemmings according to +Hinton. The baculum of _Dolomys_ has not been studied. The baculum in +_Ondatra_, and in _Prometheomys_ as illustrated by Ognev (1948:552), also +possesses well-developed processes. The baculum of _Ellobius_ is small +and lacks processes (as figured by Ognev, 1950:662). No ossification was +found in a single specimen of _Ellobius_ examined by me although the +entire glans penis was removed and cleared without dissection. So far as +known then, with the exception of _Ellobius_ and _Phenacomys longicaudus_ +(Dearden, 1958:547), the primitive microtines having rooted molars +possess bacula having three well-developed ossified processes. + +Voles of the genus _Microtus_ vary in the structure of the baculum almost +as much as do the lemmings. Within the single subgenus _Microtus_ some +individuals of _Microtus mexicanus_, for example, have minute ossified +lateral processes and other individuals lack these processes; _Microtus +pennsylvanicus_ and some other species have proportionately large lateral +ossifications. If the well-developed condition of the baculum in the +microtines having rooted molars is primitive, then within the genus +_Microtus_ those species having well-developed bacula may be considered +primitive. + +The genera _Lagurus_ and _Neofiber_ have moderately developed or +well-developed lateral processes. _Neofiber_ exhibits a tendency, not +prominent elsewhere, to have a proportionately smaller median process +rather than reduced lateral processes. + +American species of _Microtus_ (genus and subgenus) that have moderately- +to well-developed ossified lateral processes are _M. townsendii_, _M. +oeconomus_, _M. pennsylvanicus_, _M. montanus_, and _M. chrotorrhinus_. +_Microtus_ of other subgenera having this type of baculum include _M. +(Herpetomys) guatemalensis_, _M. (Chilotus) oregoni_, and _M. (Chionomys) +longicaudus_. + +American species of _Microtus_ (genus and subgenus) in which the lateral +ossifications are weakly developed or absent (although cartilaginous +lateral processes are present) include _M. mexicanus_ and _M. +californicus_. In other subgenera, species of _Microtus_ having reduced +lateral ossifications are _M. (Pedomys) ochrogaster_, _M. (Pitymys) +pinetorum_, _M. (Pitymys) parvulus_, _M. (Pitymys) quasiater_, _M. +(Arvicola) richardsoni_, and _M. (Stenocranius) miurus_. + +The microtines are essentially holarctic in distribution. Both of the +tribes, the lemmings and the voles, as well as primitive representatives +of each tribe (not considering _Ellobius_) occur in both the Old World +and New World. It is not certain on which continent (or continents) the +Microtinae first differentiated. It is certain, however, that at various +times, both early and late in the evolution of the subfamily, +representatives have crossed from Eurasia to North America or _vice +versa_. Each of 10 or more microtines in the New World is more closely +related to some microtine in the Old World than to any other microtine in +the New World. + +The similarities or differences in the baculum in Old World and New World +representatives placed in the same genus or subgenus, or thought to be +"companion species" have been commented upon in accounts of _Lemmus_, +_Dicrostonyx_, _Clethrionomys_, _Lagurus_, _Arvicola_, _Stenocranius_, +_Chilotus_, _Chionomys_, _Pitymys_, and in accounts of _Microtus +agrestis_ as compared with _M. pennsylvanicus_, and _Microtus oeconomus_ +(both Old World and New World). + +The baculum in the Microtinae more closely resembles the baculum in the +Cricetinae of the Old World than in the Murinae, or than in any other +rodents known to me. This resemblance suggests relationship between +Microtinae and Cricetinae. + + + + +LITERATURE CITED + + +ARGYROPULO, A. I. + + 1933a. Die Gattungen und Arten der Hamster (_Cricetinae_ Murray, 1866) + der Palaearktik. Zeitschr. f. Saeugetierkunde, 8:129-149, 27 figs. in + text. + + 1933b. Ueber zwei neue palaearktische Wuehlmaeuse. Zeitschr. f. + Saeugetierkunde, 8:180-183, 3 figs. in text. + +CALLERY, R. + + 1951. Development of the os genitale in the golden hamster, + _Mesocricetus (Cricetus) auratus_. Jour. Mamm., 32:204-207, 1 fig. in + text. + +CHAMBERLAIN, J. L. + + 1954. The Block Island meadow mouse, _Microtus provectus_. Jour. Mamm., + 35:587-589, 2 tables in text. + +DEARDEN, L. C. + + 1958. The baculum in _Lagurus_ and related microtines. Jour. Mamm., + 39:541-553, 1 fig. in text. + +DIDIER, R. + + 1943. L'os penien des Campagnols de France du Genre _Arvicola_. + Mammalia, 7:74-79, 10 figs. in text. + + 1954. Etude systematique de l'os penien des Mammiferes (suite), + Rongeurs: Murides. Mammalia, 18:237-256, 14 figs. in text. + +ELLERMAN, J. R. + + 1941. The families and genera of living rodents. Vol. II. Family + Muridae. The British Museum (Natural History), London, pp. xii + 690, + 50 figs. + +FRILEY, CHARLES E. + + 1947. Preparation and preservation of the baculum of mammals. Jour. + Mamm., 28:395-397, 1 fig. in text. + +HALL, E. R., and E. L. COCKRUM. + + 1953. A synopsis of the North American microtine rodents. Univ. Kansas + Publ., Mus. Nat. Hist., 5:373-498, 149 figs. in text. + +HAMILTON, W. J., JR. + + 1946. A study of the baculum in some North American Microtinae. Jour. + Mamm., 27:378-387, 3 figs. in text. + +HIBBARD, C. W., and G. C. RINKER. + + 1942. A new bog-lemming (Synaptomys) from Meade County, Kansas. Univ. + Kansas Sci. Bull., 28:25-35, 3 figs. in text. + + 1943. A new meadow mouse (_Microtus ochrogaster taylori_) from Meade + County, Kansas. Univ. Kansas Sci. Bull., 29:255-268, 5 figs. in text. + +HINTON, M. A. C. + + 1926. Monograph of the voles and lemmings (Microtinae), living and + extinct, Vol. I. British Museum (Natural History), London, pp. xvi + + 488, plus 15 plates, 110 figs. in text. + +MATTHEY, R. + + 1953. Les Chromosomes des Muridae. Revue Suisse de Zoologie, + 60:225-283, avec les planches 1 a 4 groupant 84 photomicrographies, 98 + figures et 5 schemas dans le texte. + + 1955. Nouveaux documents sur les chromosomes des Muridae. Problemes de + cytologie comparee et de taxonomie chez les Microtinae. Revue Suisse de + Zoologie, 62:163-206, avec 114 figures. + +MILLER, G. S. + + 1896. Genera and subgenera of voles and lemmings. North American Fauna + No. 12, pp. 1-85, 40 figs. and 3 plates in text. + +OGNEV, S. I. + + 1948. The mammals of Russia (USSR) and adjacent countries (The mammals + of Eastern Europe and Northern Asia), Vol. 6. Publ. Acad. Sci. USSR, + pp. 1-587, 260 figs., 12 maps, and 11 color plates in text (in + Russian). + + 1950. The mammals of Russia (USSR) and adjacent countries (The mammals + of Eastern Europe and Northern Asia), Vol. 7. Publ. Acad. Sci. USSR, + pp. 1-736, 347 figs., 15 maps, and 10 color plates in text (in + Russian). + +RUTH, E. B. + + 1934. The os priapi: A study in bone development. Anat. Rec., + 60:231-249, 16 figs. in 3 plates. + +SMITH, D. A., and J. B. FOSTER. + + 1957. Notes on the small mammals of Churchill, Manitoba. Jour. Mamm., + 38:98-115, 3 figs. and 3 tables in text. + +WHEELER, B. + + 1956. Comparison of the Block Island "species" of _Microtus_ with _M. + pennsylvanicus_. Evolution, 10:176-186, 4 figs. and 2 tables in text. + +WHITE, J. A. + + 1951. A practical method for mounting the bacula of small mammals. + Jour. Mamm., 32:125. + +ZIMMERMAN, K. + + 1955. Die Gattung _Arvicola_ Lac. im System der Microtinae. + Saeugetierkundliche Mitteilungen, 3:110-112, 2 figs. in text. + + _Transmitted August 14, 1959._ + +28-774 + + + + + UNIVERSITY OF KANSAS PUBLICATIONS + MUSEUM OF NATURAL HISTORY + + +Institutional libraries interested in publications exchange may obtain +this series by addressing the Exchange Librarian, University of Kansas +Library, Lawrence, Kansas. Copies for individuals, persons working in a +particular field of study, may be obtained by addressing instead the +Museum of Natural History, University of Kansas, Lawrence, Kansas. There +is no provision for sale of this series by the University Library which +meets institutional requests, or by the Museum of Natural History which +meets the requests of individuals. However, when individuals request +copies from the Museum, 25 cents should be included, for each separate +number that is 100 pages or more in length, for the purpose of defraying +the costs of wrapping and mailing. + +* An asterisk designates those numbers of which the Museum's supply (not +the Library's supply) is exhausted. Numbers published to date, in this +series, are as follows: + + Vol. 1. Nos. 1-26 and index. Pp. 1-638, 1946-1950. + + *Vol. 2. (Complete) Mammals of Washington. By Walter W. Dalquest. Pp. + 1-444, 140 figures in text. April 9, 1948. + + Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and + distribution. By Rollin H. Baker. Pp. 1-359, 16 figures in + text. June 12, 1951. + + *2. A quantitative study of the nocturnal migration of birds. + By George H. Lowery, Jr. Pp. 361-472, 47 figures in text. June + 29, 1951. + + 3. Phylogeny of the waxwings and allied birds. By M. Dale + Arvey. Pp. 473-530, 49 figures in text, 13 tables. October 10, + 1951. + + 4. Birds from the state of Veracruz, Mexico. By George H. + Lowery, Jr., and Walter W. Dalquest. Pp. 531-649, 7 figures in + text, 2 tables. October 10, 1951. + +Index. Pp. 651-681. + + *Vol. 4. (Complete) American weasels. By E. Raymond Hall. Pp. 1-466, 41 + plates, 31 figures in text. December 27, 1951. + + Vol. 5. Nos. 1-37 and index. Pp. 1-676, 1951-1953. + + *Vol. 6. (Complete) Mammals of Utah, _taxonomy_ and _distribution_. By + Stephen D. Durrant. Pp. 1-549, 91 figures in text, 30 tables. + August 10, 1952. + + Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303, 73 + figures in text, 37 tables. August 25, 1952. + + 2. Ecology of the opossum on a natural area in northeastern + Kansas. By Henry S. Fitch and Lewis L. Sandidge. Pp. 305-338, + 5 figures in text. August 24, 1953. + + 3. The silky pocket mice (Perognathus flavus) of Mexico. By + Rollin H. Baker. Pp. 339-347, 1 figure in text. February 15, + 1954. + + 4. North American jumping mice (Genus Zapus). By Phillip H. + Krutzsch. Pp. 349-472, 47 figures in text, 4 tables. April 21, + 1954. + + 5. Mammals from Southeastern Alaska. By Rollin H. Baker and + James S. Findley. Pp. 473-477. April 21, 1954. + + 6. Distribution of Some Nebraskan Mammals. By J. Knox Jones, + Jr. Pp. 479-487. April 21, 1954. + + 7. Subspeciation in the montane meadow mouse, Microtus + montanus, in Wyoming and Colorado. By Sydney Anderson. Pp. + 489-506, 2 figures in text. July 23, 1954. + + 8. A new subspecies of bat (Myotis velifer) from southeastern + California and Arizona. By Terry A. Vaughan. Pp. 507-512. July + 23, 1954. + + 9. Mammals of the San Gabriel mountains of California. By + Terry A. Vaughan. Pp. 513-582, 1 figure in text, 12 tables. + November 15, 1954. + + 10. A new bat (Genus Pipistrellus) from northeastern Mexico. + By Rollin H. Baker. Pp. 583-586. November 15, 1954. + + 11. A new subspecies of pocket mouse from Kansas. By E. + Raymond Hall. Pp. 587-590. November 15, 1954. + + 12. Geographic variation in the pocket gopher, Cratogeomys + castanops, in Coahuila, Mexico. By Robert J. Russell and + Rollin H. Baker. Pp. 591-608. March 15, 1955. + + 13. A new cottontail (Sylvilagus floridanus) from + northeastern Mexico. By Rollin H. Baker. Pp. 609-612. April 8, + 1955. + + 14. Taxonomy and distribution of some American shrews. By + James S. Findley. Pp. 613-618. June 10, 1955. + + 15. The pigmy woodrat, Neotoma goldmani, its distribution and + systematic position. By Dennis G. Rainey and Rollin H. Baker. + Pp. 619-624, 2 figures in text. June 10, 1955. + +Index. Pp. 625-651. + + Vol. 8. 1. Life history and ecology of the five-lined skink, Eumeces + fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in text. + September 1, 1954. + + 2. Myology and serology of the Avian Family Fringillidae, a + taxonomic study. By William B. Stallcup. Pp. 157-211, 23 + figures in text, 4 tables. November 15, 1954. + + 3. An ecological study of the collared lizard (Crotaphytus + collaris). By Henry S. Fitch. Pp. 213-274, 10 figures in text. + February 10, 1956. + + 4. A field study of the Kansas ant-eating frog, Gastrophryne + olivacea. By Henry S. Fitch. Pp. 275-306, 9 figures in text. + February 10, 1956. + + 5. Check-list of the birds of Kansas. By Harrison B. Tordoff. + Pp. 307-359, 1 figure in text. March 10, 1956. + + 6. A population study of the prairie vole (Microtus + ochrogaster) in northeastern Kansas. By Edwin P. Martin. Pp. + 361-416, 19 figures in text. April 2, 1956. + + 7. Temperature responses in free-living amphibians and + reptiles of northeastern Kansas. By Henry S. Fitch. Pp. + 417-476, 10 figures in text, 6 tables. June 1, 1956. + + 8. Food of the crow, Corvus brachyrhynchos Brehm, in + south-central Kansas. By Dwight Platt. Pp. 477-498, 4 tables. + June 8, 1956. + + 9. Ecological observations on the woodrat Neotoma floridana. + By Henry S. Fitch and Dennis G. Rainey. Pp. 499-533, 3 figures + in text. June 12, 1956. + + 10. Eastern woodrat, Neotoma floridana; Life history and + ecology. By Dennis G. Rainey. Pp. 535-646, 12 plates, 13 + figures in text. August 15, 1956. + +Index. Pp. 647-675. + + Vol. 9. 1. Speciation of the wandering shrew. By James S. Findley. Pp. + 1-68, 18 figures in text. December 10, 1955. + + 2. Additional records and extension of ranges of mammals from + Utah. By Stephen D. Durrant, M. Raymond Lee, and Richard M. + Hansen. Pp. 69-80. December 10, 1955. + + 3. A new long-eared myotis (Myotis evotis) from northeastern + Mexico. By Rollin H. Baker and Howard J. Stains. Pp. 81-84. + December 10, 1955. + + 4. Subspeciation in the meadow mouse, Microtus + pennsylvanicus, in Wyoming. By Sydney Anderson. Pp. 85-104, 2 + figures in text. May 10, 1956. + + 5. The condylarth genus Ellipsodon. By Robert W. Wilson. Pp. + 105-116, 6 figures in text. May 19, 1956. + + 6. Additional remains of the multituberculate genus + Eucosmodon. By Robert W. Wilson. Pp. 117-123, 10 figures in + text. May 19, 1956. + + 7. Mammals of Coahuila, Mexico. By Rollin H. Baker. Pp. + 125-335, 75 figures in text. June 15, 1956. + + 8. Comments on the taxonomic status of Apodemus peninsulae, + with description of a new subspecies from North China. By J. + Knox Jones, Jr. Pp. 337-346, 1 figure in text, 1 table. August + 15, 1956. + + 9. Extensions of known ranges of Mexican bats. By Sydney + Anderson. Pp. 347-351. August 15, 1956. + + 10. A new bat (Genus Leptonycteris) from Coahuila. By Howard + J. Stains. Pp. 353-356. January 21, 1957. + + 11. A new species of pocket gopher (Genus Pappogeomys) from + Jalisco, Mexico. By Robert J. Russell. Pp. 357-361. January + 21, 1957. + + 12. Geographic variation in the pocket gopher, Thomomys + bottae, in Colorado. By Phillip M. Youngman. Pp. 363-387, 7 + figures in text. February 21, 1958. + + 13. New bog lemming (genus Synaptomys) from Nebraska. By J. + Knox Jones, Jr. Pp. 385-388. May 12, 1958. + + 14. Pleistocene bats from San Josecito Cave, Nuevo Leon, + Mexico. By J. Knox Jones, Jr. Pp. 389-396. December 19, 1958. + + 15. New subspecies of the rodent Baiomys from Central + America. By Robert L. Packard. Pp. 397-404. December 19, 1958. + + 16. Mammals of the Grand Mesa, Colorado. By Sydney Anderson. + Pp. 405-414, 1 figure in text, May 20, 1959. + + 17. Distribution, variation, and relationships of the montane + vole, Microtus montanus. By Sydney Anderson. Pp. 415-511, 12 + figures in text, 2 tables. August 1, 1959. + + 18. Conspecificity of two pocket mice, Perognathus goldmani + and P. artus. By E. Raymond Hall and Marilyn Bailey Ogilvie. + Pp. 513-518, 1 map in text. January 14, 1960. + + 19. Records of harvest mice, Reithrodontomys, from Central + America, with description of a new subspecies from Nicaragua. + By Sydney Anderson and J. Knox Jones, Jr. Pp. 519-529. January + 14, 1960. + + 20. Small carnivores from San Josecito Cave (Pleistocene), + Nuevo Leon, Mexico. By E. Raymond Hall. Pp. 531-538, 1 figure + in text. January 14, 1960. + + 21. Pleistocene pocket gophers from San Josecito Cave, Nuevo + Leon, Mexico. By Robert J. Russell. Pp. 539-548, 1 figure in + text, January 14, 1960. More numbers will appear in volume 9. + + Vol. 10. 1. Studies of birds killed in nocturnal migration. By Harrison + B. Tordoff and Robert M. Mengel. Pp. 1-44, 6 figures in text, + 2 tables. September 12, 1956. + + 2. Comparative breeding behavior of Ammospiza caudacuta and + A. maritima. By Glen E. Woolfenden. Pp. 45-75, 6 plates, 1 + figure. December 20, 1956. + + 3. The forest habitat of the University of Kansas Natural + History Reservation. By Henry S. Fitch and Ronald R. McGregor. + Pp. 77-127, 2 plates, 7 figures in text, 4 tables. December + 31, 1956. + + 4. Aspects of reproduction and development in the prairie + vole (Microtus ochrogaster). By Henry S. Fitch. Pp. 129-161, 8 + figures in text, 4 tables. December 19, 1957. + + 5. Birds found on the Arctic slope of northern Alaska. By + James W. Bee. Pp. 163-211, plates 9-10, 1 figure in text. + March 12, 1958. + + 6. The wood rats of Colorado: distribution and ecology. By + Robert B. Finley, Jr. Pp. 213-552, 34 plates, 8 figures in + text, 35 tables. November 7, 1958. + + 7. Home ranges and movements of the eastern cottontail in + Kansas. By Donald W. Janes. Pp. 553-572, 4 plates, 3 figures + in text. May 4, 1959. + + 8. Natural history of the salamander Aneides hardyi. By + Richard F. Johnston and Gerhard A. Schad. Pp. 573-585. October + 8, 1959. + +More numbers will appear in volume 10. + + Vol. 11. 1. The systematic status of the colubrid snake, Leptodeira + discolor Guenther. By William E. Duellman. Pp. 1-9, 4 figures. + July 14, 1958. + + 2. Natural history of the six-lined racerunner, Cnemidophorus + sexlineatus. By Henry S. Fitch. Pp. 11-62, 9 figures, 9 + tables. September 19, 1958. + + 3. Home ranges, territories, and seasonal movements of + vertebrates of the Natural History Reservation. By Henry S. + Fitch. Pp. 63-326, 6 plates, 24 figures in text, 3 tables. + December 12, 1958. + + 4. A new snake of the genus Geophis from Chihuahua, Mexico. + By John M. Legler. Pp. 327-334, 2 figures in text. January 28, + 1959. + + 5. A new tortoise, genus Gopherus, from north-central Mexico. + By John M. Legler. Pp. 335-343. April 24, 1959. + + 6. Fishes of Chautauqua, Cowley and Elk counties, Kansas. By + Artie L. Metcalf. Pp. 345-400, 2 plates, 2 figures in text, 10 + tables. May 6, 1959. + + 7. Fishes of the Big Blue River Basin, Kansas. By W. L. + Minckley. Pp. 401-442, 2 plates, 4 figures in text, 5 tables. + May 8, 1959. + + 8. Birds from Coahuila, Mexico. By Emil K. Urban. Pp. + 443-516. August 1, 1959. + + 9. Description of a new softshell turtle from the + southeastern United States. By Robert G. Webb. Pp. 517-525, 2 + plates, 1 figure in text. August 14, 1959. + +Another number will appear in volume 11. + + Vol. 12. 1. Functional morphology of three bats: Eumops, Myotis, + Macrotus. By Terry A. Vaughan. Pp. 1-153, 4 plates, 24 figures + in text. July 8, 1959. + + 2. The ancestry of modern Amphibia: a review of the evidence. + By Theodore H. Eaton, Jr. Pp. 155-180, 10 figures in text. + July 10, 1959. + + 3. The baculum in microtine rodents. By Sydney Anderson. Pp. + 181-216, 49 figures in text. February 19, 1960. + +More numbers will appear in volume 12. + + + + + + +End of the Project Gutenberg EBook of The Baculum in Microtine Rodents, by +Sydney Anderson + +*** END OF THIS PROJECT GUTENBERG EBOOK THE BACULUM IN MICROTINE RODENTS *** + +***** This file should be named 38021.txt or 38021.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/8/0/2/38021/ + +Produced by Chris Curnow, Alex Gam, Joseph Cooper and the +Online Distributed Proofreading Team at http://www.pgdp.net + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License (available with this file or online at +http://gutenberg.org/license). + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTIBILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need, are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation web page at http://www.pglaf.org. + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Its 501(c)(3) letter is posted at +http://pglaf.org/fundraising. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at +809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email +business@pglaf.org. Email contact links and up to date contact +information can be found at the Foundation's web site and official +page at http://pglaf.org + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit http://pglaf.org + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: http://pglaf.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart is the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For thirty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + + +Most people start at our Web site which has the main PG search facility: + + http://www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/38021.zip b/38021.zip Binary files differnew file mode 100644 index 0000000..b343f45 --- /dev/null +++ b/38021.zip diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..9b383fe --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #38021 (https://www.gutenberg.org/ebooks/38021) |
