HARVARD UNIVERSITY LIBRARY OF THE Museum of Comparative Zoology The Library Museum of Comparative ZoologT Harvard University _OOLl '^ _^ ^, w- . LIBRARY OCT 151971 HARVARD CONTRIBUTIONS IN MAMmXToGY A Volume Honoring Professor E. Raymond Hall EDITED BY J. Knox Jones, Jr. Museum of Natural History The University of Kansas 1969 University of Kansas Museum of Natural History, Miscellaneous Publications II Institutional libraries interested in publications exchange may obtain this series by addressing the Exchange Librarian, The University of Kansas, Lawrence, Kansas 66044. Requests of individuals are handled instead by the Museum of Natural History, The University of Kansas, Lawrence, Kansas 66044. When individuals request copies from the Museum the amount indicated below should be included for the purpose of defraying some of the costs of producing, wrapping and mailing. Nos. G, 12, 17, 27, 36, 37, and 38 are obtainable only from the Arctic Institute. An asterisk (*) indicates that copies are no longer available from the Museum. *1. The Museum of Natural History, the University of Kansas. By E. R. Hall and Ann Murray. Pp. 1-16, illustrated. January 5, 1946. *2. Handbook of amphibians and reptiles of Kansas. By Hobart M. Smith. Pp. 1-336, 233 figures in text. September 12, 1950. *3. In memoriam, Charles Dean Bunker, 1870-1948. By E. Raymond Hall. Pp. 1-11, 1 figure in text. December 15, 1951. *4. The University of Kansas, Natural History Reservation. By Henry S. Fitch. Pp. 1-38, 4 plates, 3 figures in text. February 20, 1952. *5. Prairie chickens of Kansas. By Maurice F. Baker. Pp. 1-68, 4 plates, 15 figures in text. March 10. 1953. 6. The barren ground caribou of Keewatin. By Francis Harper. Pp. 1-163, 28 figures. October 21, 1955. Copies, paper bound, SI. 50 postpaid from the Arctic Institute of North America, 1619 New Hampshire Avenue, N. W., Washington, D. C. 20009. 7. Handbook of mammals of Kansas. By E. Raymond Hall. Pp. 1-303, illustrated. December 13, 1955. Paper bound $1.50 postpaid. 8. Mammals of northern Alaska, on the arctic slope. By James W. Bee and E. Raymond Hall. Pp. 1-309, frontispiece colored, 4 plates, 127 figures in text. March 10, 1956. Paper bound $1.00 postpaid. 9. Handbook of amphibians and reptiles of Kansas. 2nd [revised] edition. By Hobart M. Smith. Pp. 1-356, 253 figures in text. April 20, 1956. Paper bound $1.50 postpaid. *10. The raccoon in Kansas. By Howard J. Stains. Pp. 1-76, 4 plates, 14 figures in text. July 6, 1956. *11. The tree squirrels of Kansas. By Robert L. Packard. Pp. 1-67, 2 plates, 10 figures in text. August 20, 1956. 12. The mammals of Keewatin. By Francis Harper. Pp. 1-94, 6 plates. 8 figures in text. 1 map. October 26, 1956. Copies, paper bound, 75 cents postpaid from the Arctic Institute of North America, 1619 New Hampshire Avenue, N. W., Washington, D. C. 20009. *13. Museum of Natural History . . . University of Kansas. By Roy R. Moore and E. R. Hall. [An unpaged, illustrated "flier," 14 V^ in. x 8I2 in., printed on both sides, and folded twice.] June 1, 1957. *14. Vernacular names for North American mammals north of Mexico. By E. Raymond Hall, Sydney Anderson, J. Knox Jones. Jr., and Robert L. Packard. Pp. 1-16. June 19, 1957. *15. The ecology of bobwhites in south-central Kansas. By Thane S. Robinson. Pp. 1-84, 2 plates, 11 figures in text. September 6. 1957. *16 Natural history of the prairie dog in Kansas. By Ronald E. Smith. Pp. 1-36, 4 plates, 9 figures in text. June 17. 1958. 17. Birds of the Ungava Peninsula. By Francis Harper. Pp. 1-171. 6 plates, 26 figures in text. October 15, 1958. Copies, paper bound, $2.00 postpaid from the Arctic Institute of North America, 1619 New Hampshire Avenue, N. W., Washington, D. C. 20009. 18. Furbearers in Kansas: A guide to trapping. By Howard J. Stains and Rollin H. Baker. Pp. 1-100, 2 plates, 13 figures in text. November 19, 1958. Paper bound 50 cents postpaid. *19. Natural History Museum. By Roy R. Moore and E. R. Hall. [An unpaged illustrated "flier," 14'2 in. X 8V2 in., printed on both sides, and folded twice. [ May 29. 1959. 20. Handbook of gastropods in Kansas. By A. Byron Leonard. Pp. 1-224, plates 1-11, 87 figures in text. November 2, 1959. Paper bound $1.00 postpaid. 21. Management of channel catfish in Kansas. By Jackson Davis. Pp. 1-56, 8 figures in text. November 2, 1959. Paper bound 50 cents postpaid. 22. Hand-list of the birds of Kansas. By Richard F. Johnston. Pp. 1-6 [folded twice]. May 7, 1960. 10 cents postpaid. *23. Directory to the bird-life of Kansas. By Richard F. Johnston. Pp. 1-69, 1 figure in text. August 31, 1960. *24. Natural History Museum. By Roy R. Moore and E. R. Hall. [An unpaged, illustrated "flier," 141,2 in. X S'a in., printed on both sides, and folded twice. [ October 19, 1960. 25. Guide to the Panorama of North American Mammals. By E. Raymond Hall, et al. Pp. 1-31, silhouettes in black and white of Panorama, life-zones, and taped commentary for each zone. December 15, 1960. Paper bound 50 cents postpaid. *26. Beaver in Kansas. By F. Robert Henderson. Pp. 1-85, illustrated. December 16, 1960. 27. Land and fresh-water mammals of the Ungava Peninsula. By Francis Harper. Pp. 1-178, plates 1-8, 3 figures in text. August 11, 1961. Paper bound. $2.00 postpaid from tlie Arctic Institute of North America, 1619 New Hampshire Avenue, N. W., Washington, D. C. 20009. 28. Handbook of unionid mussels in Kansas. By Harold D. Murray and A. Byron Leonard. Pp. 1-184, 45 plates, 42 figures in text. May 10. 1962. Paper bound $100 postpaid. (Continued on inside back cover) MUS. lOO! ~ I _ 1 \ /-I . 1 «/ CONTRIBUTIONS IN MAMMALOGY. UNiVERsrrr. A Volume Honoring Professor E. Raymona Hall EDITED BY J. Knox Jones, Jr. Museum of Natural History The University of Kansas 1969 University of Kansas Museum of Natural History Miscellaneous Publication No. 51, pp. 1-428, 122 figs. Published July 11, 1969 Lawrence • Kansas PRINTED BY THE UNIVERSITY OF KANSAS PRINTING SERVICE 1969 ContriLutions in Mammalogy EDITED BY J. Knox Jones, Jr. - CONTENTS Preface 5 Editor's Note 6 Stephen D. Durrant, Department of Environmental Biology, The University of Utah, Salt Lake City, Utah 84112 Eugene Raymond Hall — Biography and Bibliography 9 Sydney Anderson, Department of Mammalogy, The American Museum of Natural History, New York, New York 10024 Taxonomic Status of the Woodrat, Neotoma albigula, in Southern Chihuahua, Mexico 25 Terry A. Vaughan, Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86001 Reproduction and Population Densities ln a Montane Small Mammal Fauna 51 Donald F. Hoffmeister, Museum of Natural History, University of Illinois, Urbana, Illinois 61608 The Species Problem in the Thomomys bottae — Thomomys umbrinus Complex of Pocket Gophers in Arizona 75 Ticul Alvarez, Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Mexico 17, D. F., Mexico Restos Fosiles de Mamiferos de Tlapacoya, EsTADO DE Mexico ( Pleistoceno-Reciente ) 93 James S. Findley, Department of Biology, The University of New Mexico, Albuquerque, New Mexico 87106 blogeography of southwestern boreal and Desert Mammals 113 J. Knox Jones, Jr., and Hugh H. Genoways, Museum of Natural History, The University of Kansas, Lawrence, Kansas 66044 HOLOTYPES OF ReCENT MaMMALS IN THE MuSEUM OF Natural History, The University of Kansas 129 (3) Charles L. Douglas, Texas Memorial Museum, The University of Texas, Austin, Texas 78705 Ecology of Pocket Gophers of Mesa Verde, Colorado 147 Rollin H. Baker, The Museum, Michigan State University, East Lansing, Michigan 48823 Cotton Rats of the Sigmodon fulviventer Group 177 Robert B. Finley, Jr., Section of Upland Wildlife Ecology, U.S. Fish and Wildlife Service, Denver, Colorado 80225 Cone Caches and Middens of Tamiasciurus in the Rocky Mountain Region 233 John A. White, The Museum, Idaho State University, Pocatello, Idaho 83201 Late Cenozoic Bats (Subfamily Nyctopiiylinae ) FROM THE AnZA-BoRREGO DeSERT OF CALIFORNIA 275 Henry W. Setzer, Division of Mammals. U.S. National Museum, Washington, D.C. 20560 A Review of the African Mice of the Genus Desmodilliscus Wettstein, 1916 283 Charles A. Long, Department of Biology, Wisconsin State University, Stevens Point, Wisconsin 54481 An Analysis of Patterns of Variation in Some Representative Mammalia. Part II. Studies on the Nature and Correlation of Measures of Variation 289 E. Lendell Cockrum, Department of Biological Sciences, The University of Arizona, Tucson, Arizona 85721 Migration of the Guano Bat, Tadarida brasiliensis 303 Robert J. Russell, Department of Biology, University of Missouri at Kansas City, Kansas City, Missouri 64110 Intraspecific Population Structure of the Species Pappogeomys castanops 337 Robert L. Packard, Department of Biology, Texas Technological College, Lubbock, Texas 79409 Taxonomic Reviev^ of the Golden Mouse, ochrotomys nuttalli 373 Bernardo Villa-R. and Martha Villa Cornejo, Instituto dc Biologia, Universidad Nacional Autonoma de Mexico, Mexico 20, D. F., Mexico Algunos Murcielagos del Norte de Argentina 407 (4) PREFACE This volume is dedicated to Professor E. Raymond Hall on the occasion of his retirement from the directorship of The University of Kansas Museum of Natural History on June 30, 1967. The word "retirement" for someone of Professor Hall's interests and energies has little meaning and the months following this event have wit- nessed a continuation of his active involvement in local, national, and international conservation activities, field work, scholarly re- search, and graduate teaching. The fact that the Museum of Natural History continues to flourish in an academic world where museums are sometimes poorly understood is a tribute to Professor Hall's vision and the single- mindedness of his administrative activities through the years. More important surely is the fact that the community of faculty and graduate student scholars inhabiting the Museum is singularly well adapted to relate the field of vertebrate natural history in a museum environment to the larger problems and principles of modern biol- ogy. This circumstance is due in large measure to the personal philosophy which guided Professor Hall through his years as director. The ensuing collection of articles in the field of mammalogy honoring Professor E. Raymond Hall was assembled under the editorial supervision of Professor J. Knox Jones and contains con- tributions from many of those who received advanced degrees with Professor Hall's guidance. This collection of papers, prepared especially in Professor Hall's honor, is not only an affectionate tribute to him but also an exhortation that he continue unabated the extraordinary research career that began more than 40 years ago. As Director of The University of Kansas Museum of Natural History (1944-1967), Professor Hall was a scholar-administrator for 23 years with various intermittent administrative involvements for a much longer period. Professor Hall's career is proof-positive that scholarly research, teaching, public service, and administration can form a highly productive mix and one which his successors may have difficulty emulating. Philip S. Humphrey (5) EDITOR'S NOTE Shortly after E. Raymond Hall's retirement as Director of the Museum of Natural History at Kansas, several of his former grad- uate students met to discuss means of commemorating the occasion. It was decided that a "Festschrift" of papers in mammalogy, con- tributed by his students and honoring a lifetime of teaching and research, would be eminently appropriate. Officials at The Uni- versity of Kansas, including Chancellor W. Clarke Wescoe, Provost lames R. Surface, and Dean of Faculties Francis H. Heller, en- thusiastically endorsed the project and have provided substantial financial support. All those who received the Ph.D. degree under Professor Hall's guidance were asked to contribute to the proposed volume, as were two leading Mexican mammalogists who studied at Kansas and received the M.A. degree there. Some persons contacted under- standably were unable to participate, principally because admin- istrative or other duties long had deprived them of the opportunity for active research in mammalogy. Sexenteen, however, agreed to do so, and were instructed to select from their own current research a contribution that they felt would be appropriate for the "Fest- schrift." In this way, it was hoped that the collected papers would reflect, indirectly, one aspect of Professor Hall's impact on the discipline of mammalogy. Editing of the papers that comprise "Contributions in Mam- malogy" was held to a minimum consistent with the established style of the publications of the Museum of Natural History. The present volume is number 51 of the Miscellaneous Publications of the museum, which is particularly pertinent in that E. Raymond Hall was instrumental in establishing this series as well as the familiar "University of Kansas Publications, Museum of Natural History." The outstanding workmanship and cooperation of persons at The University of Kansas Printing Service in seeing this volume through to completion is gratefully acknowledged, as is the sub- stantial editorial assistance provided by several of my graduate students, especially Elmer C. Birney, Hugh H. Genoways, Carleton J. Phillips, James D. Smith, and Ronald W. Turner. /. Knox Jones, Jr. (6) CONTRIBUTIONS IN MAMMALOGY (7) (8) EUGENE RAYMOND HALL— BIOGRAPHY AND BIBLIOGRAPHY BY Stephen D. Durrant Professor E. Raymond Hall, honored by his students and to w honi they dedicate this \'olume, was born in Imes, Kansas, on May 11, 1902, to Wilbur Downs and Susan Effie (Donovan) Hall; he married Mary Frances Harkey on August 9, 1924; three sons, Wil- liam Joel, Hubert Handel, and Benjamin Downs were born to them. His grammar school education was obtained in Kansas, as was his high school with the exception of the third year, which was taken at Yakima, Washington. He was awarded the A.B. degree from The University of Kansas in 1924. His M.A. and Ph.D. degrees were awarded by the University of California at Berkeley in 1925 and 1928, respectively ( see "Who's Who in America" ) . He has held 80 appointments and positions of local, state, univer- sity, national, and international scope. Certainly those of greatest significance to him and to his contemporaries in his chosen field are Associate Professor of Vertebrate Zoology (1937-1944), Curator of Mammals (1927-1944) and Acting Director of the Museum of Vertebrate Zoology (1938-1944) at the University of California, Berkeley, and Professor of Zoology (1944-1958), Chairman, Depart- ment of Zoology (1944-1961), Director, Museum of Natural History (1944-1967), and Summerfield Distinguished Professor (1958- present) at The University of Kansas. Under his guidance and through his efforts, the collection of mammals and the output of published information forged ahead at the Museum of Vertebrate Zoology, University of California. This was perhaps the most prolific period (1928-1944) of this museum, both in the acquisition of specimens of mammals and in the pub- lished works upon them. He returned to his Alma Mater, The University of Kansas, in 1944, as Director of the Museum of Natural History and Chairman of the Department of Zoology, which, in many ways, was perhaps the beginning of his finest hour. This museum, in 24 short years, has matured and grown in stature and recognition in all phases until at present it is one of the truly great institutions of our land. The expansion of the physical plant, the remarkable acquisitions in kinds and numbers of specimens, the gathering of outstanding scholars to (9) 10 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. conduct its acti\'ities, the number and quality of its graduate stu- dents, the hundreds of pages of printed results, and the educational opportunities provided for the entire citizenry bear direct testimony of Professor Hall's industry, devotion, and dedication. He is a member of 25 scientific societies and has held important positions in several, being a Fellow in the American Society for the Advancement of Science and Past President and Honorary Member of the American Society of Mammalogists. Moreover, he has traveled widely in North America, Central America, and Europe. While these accomplishments are remarkable and depict great energy and purpose, they are far from his greatest, which are his contributions through his students, especially his graduates, and by the printed word. The latter, as of 1968, consisted of 309 titles invohing some 5400 pages. The outstanding are "Mammals of Nevada," "The Weasels of North America," and the two volume "Mammals of North America" with K. R. Kelson (see attached Bibliography). It is impossible to totally assess his impact upon the field of taxonomic mammalogy through his students, but the fruits of his personal efforts are well known. He has named and described nine new genera, a new subgenus, 23 new species, and 138 new subspecies of both fossil and Recent mammals. Four kinds, Lutravus halli Furlong, Verognathoides halli Wood, Microtus longicaudus haUi Ellerman, and Taxidea taxus halli Schantz, have been named in his honor, and another is named in this \'olume. Investigations have failed to disclose another person of our time who sits so high in the saddle or who has cast a wider or longer shadow of accomplishment over this field of endeavor. In the field of taxonomic mammalogy, he and his intellectual sons and grandsons are in the forefront in positions and prestige. Anywhere where taxo- nomic mammalogy is pursured his influence is felt by his writings, his students, or his students' students and their total productivity. Penetrating studies of his disposition and capacities enable one to understand and evaluate the personal characteristics that have aided him to mount such a high pinnacle of achievement. Doctor Hall has an extremely intense dedication to his work, a nearly fierce belief in the efficacy of the problem at hand and his position with reference to it, and unlimited determination and physical capacity to see projects established and carried to completion. In many respects he is a stormy petrel or at least a highly con- troversial figure. Once committed to a course of action, his dogged persistence, his unrelenting attack, his singleness of purpose, and DuRRANT — Hall Biography and Bibliography 11 his characteristic shouldering aside of opposition usually have led him to the attainment of his goals. If thwarted in one approach, he stubbornly launches a new attack from a new, different stance. To friend, he is a great source of support and encouragement; his opponents soon learn they have a man to be measured and an adversary worthy of their steel. To him, the written word, whether in manuscript, galley, page proof, or printed, possesses a certain sanctity. His students well remember some of his idiosyncrasies in his efforts to arrive at excel- lence. Comments like: "You cannot encounter a mouse"; "To begin a sentence with 'however' is poor"; "Be careful of the use of 'due to,' especially with an adverbial modifier"; "Use first usages in the dictionary"; "Be careful of the use of the word 'type.' " Whether they agreed or not, all his students were impressed by the fact that when their manuscripts were returned, they were the best he was capable of making them. In some ways, he had a sixth sense of timing to keep a student totally productively occupied (sometimes fretfully) from the inception of his study to just a few moments before the deadline. To all these accomplishments there are many as yet unsensed and uncatalogued to be brought into full fruition in decades to come. It has often been stated that no one can ever know the total effects of a stone thrown into a quiet pool. Likewise, it would be impossible to completely assess the total impact of our man of the hour upon the hundreds of persons with whom he has come into contact both in and out of his chosen field. Moreover, the situation is not to be likened to that of a quiet pool and the effects in a turbulent one undoubtedly would be tremendously pronounced and increased both in scope and intensity. His students and colleagues stand in his honor, respect his con- tributions, hope for his continued productivity, and dedicate this volume to him as a monument to his endeavors and accomplish- ments. It might be said of him that he belongs to that select few who during their lifetime have seen their realizations far exceed theii- fondest expectations. Bibliography of E. Raymond Hall, 1921-1968 1921 1. Golden- winged warbler in Kansas. Auk, 38:607, December 16. 192.3 2. Occurrence of the hoary bat at Lawrence, Kansas. Join-. Manim., 4:192- 193, August 10. 12 Misc. PuBL. 51, Univ. Kansas Mus. Nat. Hist. 3. Winter visitors at Lawrence, Kansas. Auk, 40:701-702, October 10. 1925 4. Pelicans versus fishes in Pyramid Lake. Condor, 27:147-160, July 15. 1926 5. A new subspecies of the California spotted skunk ( Spilogale phenax Merriam). Jour. Mamm., 7:53-56, February 15. 6. Changes during growth in the skull of the rodent Otospermophilus gram- murus beecheyi. Univ. California Publ. ZooL, 21:355-404, 43 figs., March 9. 7. Notes on water birds nesting at Pyramid Lake, Nevada. Condor, 28: 87-91, March 15. 8. A new marten from the Pleistocene cave deposits of California. Jour. Mamm., 7:127-130, 1 pi.. May 13. 9. The abdominal skin gland of Martes. Jour. Mamm., 7:227-229, August 9. 10. Economic value of Mexican free-tailed bat. California Fish and Game, 12:135-137, September 1. 11. Golden eagle extermination in England. California Fish and Game, 12: 139, September 1. 12. [Review of] New teachers bulletin on fish and game laws. California Fish and Game, 12:143, September 1. 13. Barbed wire fence causes death of deer. California Fish and Game, 12: 151-152, fig. 29, September 1. 14. Forage habits of pocket gopher. California Fish and Game, 12:152, Sep- tember 1. 15. Arkansas still has no protection on fish. California Fish and Game, 12:153, September 1. 16. New method of predatory mauunal control. California Fish and Game, 12:154, September 1. 17. Oil pollution. California Fish and Game, 12:154, September 1. 18. Systematic notes on the subspecies of Bassariscus astutus with description of one new form from California. Univ. California Publ. Zool., 30:39-50, pis. 2-3, September 8. 19. The muscular anatomv of three mustelid mammals. Mephitis, Spilogale and Martes. Univ. California Publ. Zool., 30:7-38, 5 figs., September 14. 1927 20. An outbreak of house mice in Kern County, California. Univ. California Publ. Zool., 30:189-203, February 21. 21. Species of the mammalian subfauiily Bassariscinae. Univ. California Publ. Geol. Sci., 16:435-448, pi. 64, 2 figs., March 17. 22. Notes on the birds of Douglas County, Kansas. Wilson Bull., 39:91-105, June (with J. Linsdale). 23. The muscular anatomy of the American badger (Taxidea taxus). Univ. California Publ. Zool., 30:205-219, 2 figs., July 28. 24. The deer of California. California Fish and Game, 13:233-259, figs. 49-62, November 5. 25. A commensal relation of the California (luail with the California ground squirrel. Condor, 29:271, November 15. 26. The barn owl in its relation to the rodent population at Berkeley, Cali- fornia. Condor, 29:274-275, November 15. 27. A new weasel from Louisiana. Proc. Biol. Soc. Washington, 40:193-194, December 2. 1928 28. A correction [for The deer of California]. California Fish and Game, 14: 51-52, January 30. DuRRANT — Hall Biography and Bibliography 13 29. A new race of black bear from Vancoiner Island, British Columbia, with remarks on other Northwest Coast forms of Euractos. Uni\'. California Piibl. Zool., 30:231-242, March 2. 30 Records of supernumerary teeth in bears. Univ. California Publ. Zool., 30:243-250, pis., 14-15, 1 fig., March 2. 31. Distribution and speciation in American weasels (subgenus Mustela). Pro- gramme, Ph.D. degree, Univ. California Grad. Div., 4 pp., May 8. 32. Notes on the life history of the sage-brush meadow mouse (Lagurus). Jour. Mamm., 9:201-204, August 9. 33. Note on the life history of the woodland deer mouse. Jour. Mamm., 9: 255-256, August 9. 34. Weasels wanted. Missouri Game and Fish News, 4(12): 17, December. 1929 35. On the question of, "Is it right to protect the female of the species at the cost of the male?" Canadian Field-Nat., 43:59, March. 36 A second new genus of hedgehog from the Pliocene of Nevada. Univ. California Publ. Geol. Sci., 18:227-231, 6 figs., March 19. 37. Nhrmmals collected by Charles D. Brower at Point Barrow, Alaska. Univ. California Publ. Zool., 30:419-425, March 19. 38. Notes on the life history of the kangaroo mouse (Microdipodops). Jour. Mamm., 10:298-305, pi. 22, November 11 (with J. Linsdale). 39. California mink in marine habitat. Jour. Mamm., 10:351-352, November 11. 40. A "den" of rattlesnakes in eastern Nevada. Bull. Antivenin Inst. Anier., 3:79-80, fig. 5, November. 1930 41. A bassarisk and a new mustelid from the later Tertiary of California. Jour. Mamm., 11:23-26, 2 figs., February 11. 42. Three new genera of Mustelidae from the later Tertiary of North America. Jour. Mamm., 11:146-155, pis. 7-8, May 9. 43. Statement at "Hearing before the Committee on Agriculture House of Representatives seventy-first Congress second session on H. R. 9599 by Mr. Leavitt, a bill to authorize the Secretary of Agriculture to carry out his ten-year cooperative program for the eradication, suppression, or bringing under control of predatory and other wild animals injurious to agriculture, horticulture, forestry, animal husbandry, wild game, and other interests, and for the suppression of rabies and tularemia in predatory or other wild animals for other pmposes." Pp. 57-65, May. 44. Three new pocket gophers from Utah and Nevada. Univ. California Publ. Zool., 32:443-447, July 8. 45. Predatory mammal destruction. Jour. Mamm., 11:362-369, August 9. 46. Rodents and lagomorphs from the later Terriary of Fish Lake Valley, Nevada. Univ. California Publ. Geol. Sci., 19:295-312, pi. 37, 29 figs., November 25. 47. Rodents and lagomorphs from the Barstow beds of southern California. Univ. California Publ. Geol. Sci., 19:313-318, 7 figs., November 25. 48. A new genus of bat from the later Tertiary of Nevada. Univ. California Publ. Geol. Sci., 19:319-320, pi. 38, November 25. 1931 49. On the occurrence of certain mammals in extreme southwestern Wash- ington. Murrelet, 12:22, January. 50. The poisoner again [in two parts]. Outdoor Life, 47(4):26-27, 82-84, March, and 47(5):28-29, 62-63, April. 14 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 51. Critical comments on mammals from Utah, with descriptions of new forms from Utah, Nevada and Washington. Univ. California Piibl. Zool., 37: 1-13, April 10. 52. Description of a new mustelid from the later Tertiary of Oregon, with assignment of Parictis primaevus to the Canidae. lour. Mamm., 12:156- 158, pi. 5, May 14. 53. Tree climbing Callospermophiliis. Murrelet, 12:54-55, May. 54. A new subspecies of Peromyscus from San Jose Island, Lower California, Mexico. Proc. Biol. Soc. Washington, 44:87-88, June 29. 55. The coyote and his control. California Fish and Game, 17:283-290, figs. 88-89, July. 56. A skull of Nothocyon from the John Day Oligocene. Univ. Kansas Sci. Bull., 19:283-286, pi. 29, for July, 1930, but printed about August, 1931 (with H. T. Martin). 19.32 57. Editorial [no title]. Condor, 34:52, January 15. 58. New pocket gophers from Nevada. Univ. California Publ. Zool., 38:325- 333, February 27. 59. A new pocket gopher from Lower California, Mexico. Proc. Biol. Soc. Washington, 45:67-70, April 2. 60. A new black-tailed jack-rabbit from Idaho. Proc. Biol. Soc. Washington, 45:71-72, April 2 (with W. B. Whitlow). 61. Three new pocket gophers from New Mexico and Arizona. Proc. Biol. Soc. Washington, 45:95-98, June 21. 62. A new shrew of the Sorex merriami group from Arizona. Jour. Mamm., 13:259-262, pi. 13, August 9. 63. A new weasel from Panama. Proc. Biol. Soc. Washington, 45:139-140, September 9. 64. New mammals from St. Lawrence Island, Bering Sea, Alaska. Univ. California Publ. Zool., 38:391-404, pis. 5-6, 1 fig., September 17 (with R. M. Gilmore). 65. A new pocket gopher from New Mexico. Univ. California Publ. Zool., 38:411-413, September 20. 66. Remarks on the affinities of the mammalian fauna of Vancouver Island, British Columbia, with descriptions of new subspecies. Univ. California Publ. Zool., 38:415-423, November 8. 1933 67. The Asiatic genus Eomellivora in the Pliocene of California. Jour. Mamm., 14:63-65, pi. 4, February 14 (with C. Stock). 68 A new race of pocket gopher found in Oregon and Washington. Proc. Biol. Soc. Washington, 46:41-44, March 24 (with R. T. Orr). 69. Sorex leucogenys in Arizona. Jour. Mamm., 14:153-154, May 15. 70 Mammals of the Pocatello region of southeastern Idaho. Univ. California Publ. Zool., 40:235-277, 3 figs., September 30 (with W. B. Whitlow). 71. Arrangement of the obturator muscles with notes on the other muscles of the thigh, in the dwarf wapiti (Cervus nannodes Merriam). Jour. Manun., 14:358-361, 2 figs., November 13 (with A. H. Miller). 72. Dermestid beetles as an aid in cleaning bones. Jour. Mamm., 14:372-374, November 13 (with W. C. Russell). 1934 73. Notes on Arizona Rodents. Proc. Biol. Soc. Washington, 47:51-56, Feb- ruary 9 (with W. B. Davis). 74 A new race of chipmunk from the Great Basin in western United States. Univ. California Publ. Zool., 40:321-326, 1 Bg., February 12 (with D. M. Hatfield). 75 Certain osteological features of Eudernia maculatum (J. A. Allen). Jour. Mamm., 15:68-70, 8 figs., February 15. DuRRANT — Hall Biography and Bibliography 15 76. The coyote and his control. Outdoor Life, 73(4):30-32, March. 77. Marmota caHgata broweri, a new marmot from northern Alaska. Canadian Field-Nat., 48:57-59, 6 figs., April (with R. M. Gilmore). 78. Sorex melanogenys Hall, a synonym of Sorex vagrans monticola Merriam. Jour. Mamm., 15:155, May 15. 79. A new pika (mammalian genus Ochotona) from central Nevada. Proc. Biol. Soc. Washington, 47:103-106, June 13. 80. Statement of Dr. E. Raymond Hall on grazing of sheep on the public domain and in the National Forests. Pp. 176-177, in Grazing Sheep in National Forests, Hearing before the Special Committee on Conservation of Wild Life Resources, United States Senate, Seventy-third Congress, second session. 81. Two new rodents of the genera Glaucomys and Zapus from Utah. Occas. Papers, Mus. Zool., Univ. Michigan, 296:1-6, November 2. 82. Mammals collected by T. T. and E. B. McCabe in the Bowron Lake region of British Columbia. Univ. California Publ. Zool., 40:363-386, 1 fig., November 5. 1935 83. Geographic distribution of pocket gophers (genus Thomomys) in Nevada. Univ. California Publ. Zool., 40:387-402, 1 fig., March 13 (with W. B. Davis). 84. A new mustelid genus from the Pliocene of California. Jour. Mamm., 16:137-138, 3 figs.. May 15. 85. Occurrence of the spotted bat at Reno, Nevada. Jour. Mamm., 16:148, May 15. 86. A new weasel from Peru. Proc. Biol. Soc. Washington, 48:143-146, August 22. 87. Nevadan races of the Microtus montanus group of meadow mice. Univ. California Publ. Zool., 40:417-428, 1 fig., October 25. 1936 88. A new meadow mouse from Bowen Island, British Columbia. Murrelet, 17:15-16, March 7. 89. Identity of the Bowron Lake moose of British Columbia. Murrelet, 17:17, March 7. 90. A new pocket gopher from New Mexico. Jour. Washington Acad. Sci., 26:296-298, July 15. 91. Ranges and relationships of certain mammals in southwestern Utah. Proc. Utah Acad. Sci., Arts and Letters, 13:211-213, September 15 (with C. C. Presnall). 92. Mustelid mammals from the Pleistocene of North America with systematic notes on some Recent members of the genera Mustela, Taxidea and Mephitis. Publ. Carnegie Inst. Washington, 473:41-119, pis. 1-5, 6 figs., November 20. 1937 93. Mustela cicognanii, the short-tailed weasel, incorrectly ascribed to Ohio. Amer. Midland Nat., 18:304, March. 94. Lafayette sunshine. Lafayette Sun, 1 p. (with M. F. Hall). 95. [Review of] October farm, from the Concord Journals of William Brew- ster. Jour. Mamm., 18:245, May 14. 96. A new kangaroo mouse (Microdipodops) of Utah and Nevada. Jour. Mamm., 18:357-359, August 14 (with S. D. Durrant). 97. Deleterious eftects of preservatives on study specimens of mammals. Jour. Mamm., 18:359-360, August 14. 1938 98. Fur and the public domain. The trapper and sportsman, 1(1):12-14, January. 16 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 99. A new pocket gopher from Nevada. Proc. Biol. Soc. Washington, 51: 15-16, February 18 (with F. E. Durham). 100. A new weasel from Bolivia and Peru. Proc. Biol. Soc. Washington, 51: 67-68, March 18. 101. Gestation period in the long-tailed weasel. Jour. Mamm., 19:249-250, May 14. 102. Notes on the spotted skunks (genus Spilogale), with accounts of new sub- species from Me.xico and Costa Rica. Ann. Mag. Nat. Hist., ser. 2, 1:510- 515, May. 103. Notes on the meadow mice Microtus niontanus and M. nanus with de- scription of a new subspecies from Colorado. Proc. Biol. Soc. Washington, 51:131-134, August 23. 104. Mammals from Millard County, Utah. Proc. Utah Acad. Sci., Arts and Letters, 15:121-122, June (with D. H. Johnson). 105. Variation among insular mammals of Georgia Strait, British Columbia. Amer. Nat., 72:453-463, 2 figs., September 10. 106. Mammals from Touchwood Hills Saskatchewan. Canadian Field-Nat., 52:108-109, October. 107. A new pika from southeastern Idaho with notes on nearby subspecies. Univ. California Publ. Zool., 42:335-340, 1 fig., October 12 (with H. L. Bowlus). 108. Inyo screech owl at Fallon, Nevada. Condor, 40:259, November 15. 109. Broad-tailed hummingbird attracted to food of red-naped sapsucker. Con- dor, 40:264, November 15. 19.39 110. The spotted bat in Kern County, California. Jour. Mamm., 20:103, Feb- ruary 14. 111. Deux sous-especes nouvelles du rongeur Dipodomijs ordii de I'ouest des Etats-Unis D'Amerique. Mammalia. 3:10-16, 1 pi., March (with S. D. Durrant ) . 112. Three new pocket gophers (mammalian genus Thomomys) from Wash- ington. Murrelet, 20:3-5, April 30 (with W. W. Dalquest). 113. Extension of the known geographic range of the striated chipmunk (Ta- mias straitus). Amer. Midland Nat., 21:766, May. 114. On the characters of the pocket gopher Thomomys talpoides couchi Gold- man. Murrelet, 20:38-39, August (with W. W. Dalquest). 115. Joseph Grinnell — obituary. Murrelet, 20:46-47, 1 photograph, August. 116. A new subspecies of beaver from Colorado. Jour. Mamm., 20:358-362, 1 fig., August 14 (with E. R. Warren). 117. The grizzly bear of California. California Fish and Game, 5:237-244, 2 pis., 1 fig., September. 118. Remarks on the primitive structure of Mustek stolzmanni with a list of the South American species and subspecies of the genus Mustcla. Physis (Revista de la Sociedad Argentina de Ciencias Naturales), 16:159-178, 2 maps, 1 pi. 119. [Review of] Revision of the North American ground squirrels with a classification of the North American Sciuridae. Saugetierk., 13:184-188, September 1. 120. Joseph Grinnell [obituary notice]. Jour. Wildlife Mgt., 3:366-368, October. 121. Una nueva especie de comadreje de Bolivia y del Peru. Bol. Mus. Hist. Nat., Javier Prado, 3:95-97, October [translation of contribution no. 100]. 122. Geographic races of the kangaroo rat, Dipodomys microps. Occas. Papers Mus. Zool.. Louisiana State Univ., 4:47-62, 3 figs., November 10 (with F. H. Dale). 123. Joseph Grinnell (1877 to 1839) — biographical notes. Jour. Mamm., 20: 409-417, November 14. 124. Utah jumping mouse recorded from Idaho. Murrelet, 20:71, December. DuRRANT — Hall Biography and Bibliography 17 1940 125. An ancient nesting site of the white pelican in Nevada. Condor, 42:87-88, 1 fig., January 19. 126. A new race of beaver from Oregon. Jour. Mamm., 21:87-89, Fel)ruary 14 (with S. G. Jewett). 127. Gifts of specimens to the California Museum of Vertebrate Zoology, June 1, 1936, to June 30, 1939. Univ. California Press, pp. 1-21, March 1. 128. Superninnerary and missing teeth in wild mammals of the orders Insecti- vora and Carnivora, with some notes on disease. Jour. Dental Res. 19:103- 119, pis. 1-12, April. 129. The Pinyon mouse (Peromyscus truei) in Nevada, with description of a new subspecies. Univ. CaHfornia Publ. Zool., 42:401-405, 1 fig., April 30 (with D. F. Hofl meister ) . 130. Pribilof fur seal on California Coast. California Fish and Game, 26:76-77. 131. Transplantation of the Douglas Ground Squirrel. California Fish and Game, 26:77. 132. A curious mutation in a coyote from Kern County, California. California Fish and Game, 26:393-395, 2 figs., December. 133. Capture of a coati (Nasiia narica) in San Diego County, California. Cali- fornia Fish and Game, 26:395, December. 134. A new chipmunk of the Eutamias amoenus group from Nevada. Proc. Biol. Soc. Washington, 53:155-156, December 19 (with D. H. Johnson). 135. A new race of Belding ground squirrel from Nevada. Murrelet, 21:59-61, 1 fig., December 20. 1941 136. Freak antlers of mule deer. CaHfornia Fish and Game, 27:37-39, 2 figs., March 27. 137. Deer has no gall bladder. Pacific Rural Press, 131:289, April. 138. Two new kangaroo mice from Utah. Murrelet, 22:5-7, April 30 (with S. D. Durrant). 139. New heteromyid rodents from Nevada. Proc. Biol. Soc. Washington, 54: 55-62, May 20. 140. Three new mammals ( Microtus and Ochotona) from Utah. Great Basin Nat, 2:105-108, July 20 (with L. C. Hayward). 141. [Re\iew of] Distribution and variation in the native sheep of North America. Jour. Mamm., 22:332, August 14. 142. [Review of] Bibliography of fossil vertebrates. Jour. Mamm., 22:333, August 14. 143. Revision of the rodent genus Microdipodops. Field. Mus. Nat. Hist., Zool. Ser., 27:233-277, 8 figs., December 8. 1942 144. The type specimen of Aplodontia rufa californica (Peters). Murrelet, 22:4.5-51, January 20. 145. Geographic variation in the canyon mouse, Peromyscus crinitus. Jovu. Mamm., 23:51-65, 1 fig., February 14 (with D. F. Hoff meister ) . 146. [Re\'iew of] Mammalia [being part 65 of the zoology of the Faroes]. Jour. Mamm., 23:100-101, February 14. 147. Joseph Grinnell, 1877 to 1939. Boone and Crockett Club, officers, by- laws, treasurer's report and list of members for the years 1940-1941, pp. 32-33, July 1, 1941 [unsigned]. 148. A new race of wood rat (Neotoma lepida). Univ. California Publ., Zool., 46:369-370, July 3. 149. Gestation period in the fisher with recommendations for the animal's pro- tection in California. California Fish and Came, 28:143-147, 1 fig., August. 18 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 150. Fur bearers and tlie war. Trans. 7th N. Amer. Wildlife Conf., pp. 472-475, and discussion, pp. 474-480, November. 194.3 151. New genus of American Pliocene badger, widi remarks on the relation- ships of badgers of the northern hemisphere. Abstr. Soc. Vert. Paleo., pp. 1841-1842. 152. [Review of] The Ohio Recent mammal collection in the Cleveland Museum of Natural History. Jour. Mamm., 24:105, February 20. 153. [Review of] Furred animals of Australia. Jour. Mamm., 24:105-106, Feb- ruary 20. 154. Cranial characters of a dog-coyote hybrid. Amer. Midland Nat., 29:371- 374, 2 figs., March. 155. Intergradation \'ersus hybridization in ground squirrels of the western United States. Amer. Midland Nat., 29:375-378, 1 fig., March. 156. Criteria for vertebrate subspecies, species and genera: the mammals. Ann. New York Acad. Sci., 44:141-144, June 8. 157. U.S. textbooks for students in Latin American universities. Science, 98: 15-16, July 2. 158. [Review of] Joseph Grinnell's philosophy of nature. Audubon Mag., 45: 252-253, August. 159. Oscar Perry Silhman — obituary notice. Jour. Mamm., 24:420, August 17. 1944 160. Pelicans of the past. Nature Mag., 37:156, 162, March. 161. Four new ermines from the islands of southeastern Alaska. Proc. Biol. Soc. Washington, 57:35-42, June 28. 162. A new genus of American Pliocene badger, with remarks on the relation- ships of badgers of the Northern Hemisphere. Publ. Carnegie Inst. Wash- ington, 551:9-23, 2 pis., 2 figs., July 18. 163. Classification of the ermines of eastern Siberia. Proc. California Acad. Sci., 23:555-560, 1 fig., August 22. 164. Speciation in the American genus Mustek. Anat., Rec, 89:5.50, August. 165. [Review of] The armadillo: its relation to agriculture and game. Jour. Wildlife Mgt., 8:342-343, October. 1945 166. Four new ermines from the Pacific Northwest. Jour. Mamm., 26:78-85, February 27. 167. Chase Littlejohn, 1854 to 1943: observations by Littlejohn on hunting sea otters. Jour. Mamm., 26:89-91, February. 168. [Review of] The mammals of Chile. Jour. Mamm., 26:97-98, Febmary 27. 169. Dental caries in bears. Trans. Kansas Acad. Sci., 48:79-8.5, 4 pis. 170. Some mammals of Ozark County, Missouri. Jour. Mamm., 26:142-145, July 13 (with A. S. Leopold). 171. A revised classification of the American ermines with description of a new subspecies from the western Great Lakes region. Jour. Mamm., 26:175- 182, 1 fig., July 13. 1946 172. The Museum of Natural History, The University of Kansas. Misc. Publ., Mus. Nat. Hist., Univ. Kansas, 1:1-16, illustrated, January 5. 173. Mammals of Nevada. Univ. California Press, Berkeley, .\i + 710 pp. frontispiece, 11 pis., 485 numbered figs, and 54 unnum]:)ered figs., 2 charts, July 1. 174. [Review of] The principles of classification and a classification of mam- mals. Jour. Mamm., 27:287-288, August 14. DuRRANT — Hall Biography and Bibliography 19 175. Zoological subspecies of man at the peace table. Jour. Mamm., 27:358- 364, 2 figs., November 25. 1947 176. [Re\ie\v of] Atlas des mammiferes de France. Jour. Mamm., 28:69, Feb- ruary 17. 177. [Re\ie\v of] The California ground squirrel. Ecology, 28:211, April. 178. [Re\ie\v of] Catalogue of Canadian Recent mammals. Jour. Mamm., 28: 304, August 19. 179. Subspeciation in pocket gophers of Kansas. Univ. Kansas Publ., Mus. Nat. Hist., 1:217-236, 2 figs., November 29 (with B. Villa-R.). 180 A new bat (genus Myotis) from Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 1:237-244, 6 figs., December 10 (with W. W. Dalquest). 181. Tadarida femorosacca (Merriam) in Tamaulipas, Mexico. Univ. Kansas Publ, Mus. Nat. Hist., 1:245-248, 1 fig., December 10 (with W. W. Dalquest ) . 182. Obituary [Ralph Ellis (1908-1945)]. Proc. Linnean Soc. London, 159: 158-159, December 30. 183. Geographic range of the hairy-legged vampire in eastern Mexico. Trans. Kansas Acad. Sci., vol. 50:315-317, December 30 (with W. W. Dalquest). 1948 184. Pipistrellus cinnamomeus rediscovered. Jour. Mamm., 29:180, May 14 (with W. W. Dalquest). 185. A new pocket gopher (Thomomys) and a new spiny pocket mouse (Liomys) from Michoacan, Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 1:249-256, 6 figs., July 26 (with B. Villa-R.). 186. Two new meadow mice from Michoacan, Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 1:423-427, 6 figs., December 24. 1949 187. [Review of] Ecology of the California groimd squirrel on grazing lands. Ecology, 30:112, January. 188. Paul Rode: 1901-1948. Science, 110:51, July 8. 189. Paul Rode: 1901-1948. Jour. Mamm., 30:341-342, August 17. 190. A new subspecies of the cotton rat, Sigmodon hispidus, from Michoacan, Me.xico. Proc. Biol. Soc. Washington, 62:149-150, 3 figs., August 23. 191. A new subspecies of funnel-eared bat (Natalus mexicanus) from eastern Mexico. Proc. Biol. Soc. Washington, 62:153-154, August 23 (with W. W. Dalquest ) . 192. A new harvest mouse from Michoacan, Mexico. Proc. Biol. Soc. Wasliing- ton, 62:163-164, August 23. 193. Un nuevo raton de campo genero Reithrodontomys de Michoacan, Mex- ico. Anuarie por 1947 de la Comision Impulsora y Coordinadora de la Investigacion Cientifica, pp. 173-175, September 18 (with B. Villa-R.). 194. Five bats new to the known fauna of Mexico. Jour. Mamm., 30:424-427, November 14 (with W. W. Dalquest). 195. Observaciones acerca de la preparacion de trabajos cientificos. Univ. Nac. Mexico, Publ. Inst. Biol., 44:1-10, December 3. 196. An annotated list of the mammals of Michoacan, Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 1:431-472, 2 pis., 1 fig., December 27 (with B. Villa-R.). 1950 197. Geographic range of the hooded skunk. Mephitis macroura, with de- scription of a new subspecies from Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 1:575-580, 1 fig., January 20 (with W. W. Dalquest). 198. Pipistrellus cinnamomeus Miller 1902 referred to the genus Myotis. Univ. Kansas Publ., Mus. Nat. Hist., 1:581-590, 5 figs., January 20 (with W. W. Dalquest ) . 20 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 199. A synopsis of the American bats of the genus Pipistrelkis. Univ. Kansas Publ., Mus. Nat. Hist., 1:591-602, 1 fig., January 20 (with W. W. Dal- quest). 200. Speciation in American weasels (genus Mustek). Proc. 13th Internat. Cong. Zool., pp. 404-405. 201. Lista anotada de los mammiferos de Michoacan, Mexico. An. Inst. Biol., 21:159-214, 5 figs., September 28 (with B. Villa-R.). 202 State administration of wildhfe, a natural resource. Trans. Kansas Acad. Sci., 53:295-301, October 3. 203. Kansas wildlife can be saved. Southwest Farmer, Wichita Beacon, p. 11, 1 fig., November 5. 1951 204 Two new pocket gophers from Wyoming and Colorado. Univ. Kansas Pul)l., Mus. Nat. Hist., 5:25-32, February 28 (with G. H. Montague). 205. A northern record for Centronycteris maxmiliaiii centralis with a key to the skulls of the North American emballonurine bats. An. Inst. Biol., 21:431- 433, March 6 (with W. W. Dalquest and W. G. Frum). 206. The gross anatomy of the tongues and stomachs of eight New World bats. Trans. Kansas Acad. Sci., 54:64-72, 34 figs., March 17 (with H. Park). 207. An instance of coyote-dog hybridization. Trans. Kansas Acad. Sci., 54: 73-77, 4 figs., March 17 (with J. W. Bee). 208. Mammals collected by Dr. Curt von Wedel from the barrier beach of Tamauhpas, Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 5:33-47, 1 fig., October 1. 209. Comments on the taxonomy and geographic distribution of some North American rabbits. Univ. Kansas Publ., Mus. Nat. Hist., 5:49-58, October 1 (with K. R. Kelson). 210. A new subspecies of Microtus montanus from Montana and comments on Microtus canicaudus Miller. Univ. Kansas Publ., Mus. Nat. Hist., 5:73-79, October 1 (with K. R. Kelson). 211. A new pocket gopher from eastern Colorado. Univ. Kansas Publ., Mus. Nat. Hist., 5:81-85, October 1. 212. An hypothesis to account for the winter whitening of Arctic mammals. Anat. Rec. 3: no page number, November. 213 A synopsis of the North American Lagomorpha. Univ. Kansas Publ., Mus. Nat. Hist., 5:119-202, 68 figs., December 15. 214 A new pocket gopher (genus Thomomys) from Wyoming and Colorado. Univ. Kansas Publ., Mus. Nat. Hist., 5:219-222, December 15. 215. A new name for the Mexican red bat. Univ. Kansas Publ., Mus. Nat. Hist., 5:223-226, December 15. 216. In memoriam. Charles Dean Bunker 1870-1948. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 3:1-11, 1 fig., December 15. 217. American weasels. Univ. Kansas Publ, Mus. Nat. Hist., 4:1-466, 41 pis., 31 figs., December 27. 1952 218 Taxonomic notes on Mexican bats of the genus Rhogeessa. Univ. Kansas Publ., Mus. Nat. Hist., 5:227-232, April 10. 219 Comments on the taxonomy and geographic distribution of North Ameri- can microtines. Univ. Kansas Publ., Mus. Nat. Hist., 5:293-312, Novem- ber 17 (with E. L. Cockrum). 220 The subspecific status of t\vo Central American slodis. Univ. Kansas Publ., Mus. Nat. Hist, 5:313-317, November 21 (with K. R. Kelson). 221. Comments on the taxonomy and geographic distribution of some North American marsupials, insectivores and carnivores. Univ. Kansas Publ., Mus. Nat. Hist., 5:319-341, December 5 (with K. R. Kelson). DuRRANT — Hall Biography and Bibliography 21 222. Comments on the taxonomy and geographic distribution of some North American rodents. Univ. Kansas Publ., Mus. Nat. Hist., 5:343-371, De- cember 15 (with K. R. Kelson). 1953 223. A synopsis of the North American microtine rodents. Univ. Kansas Publ, Mus. Nat. Hist., 5:373-498, 149 figs., January 15 (with E. L. Cockrum). 224. A westward extension of known geographic range for the timber rattle- snake in southern Kansas. Trans. Kansas Acad. Sci., 56:89, March 21. 225. Seventeen species of bats recorded from Barro Colorado Island, Panama Canal Zone. Univ. Kansas Publ, Mus. Nat. Hist., 5:641-646, December 1 (with W. B. Jackson). 1954 226. Occurrence of the harbor porpoise at Point Barrow, Alaska. Jour. Mamni., 35:122-123, February 10 (with J. W. Bee). 227. A new subspecies of pocket mouse from Kansas. Univ. Kansas Publ., Mus. Nat. Hist., 7:587-590, November 15. 1955 228. On the legitimacy of scientific authorship. Science, 121:40-41, January 7. 229. Nuevos murcielagos para la fauna Mexicana. Acta Zool. Mexicana, 1(3): 1-2, September 10. 230. A new subspecies of wood rat from Nayarit, Mexico, with new name- combinations for the Neotoma mexicana group. Jour. Washington Acad. Sci., 45:328-332, 1 fig., October 31. 231. Handbook of mammals of Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 7:1-303, illustrated, December 13. 1956 232. What goes on under your farm? Capper's Farmer, 67(3):37, 129-131, 1 colored two-page illustration, February 13. 233. Harry Harris [obituary notice]. Burrough Club Bull., 7(4):3-4, February. 234. Future fishing and hunting in Kansas. Kansas Sportsman, 2(ll):4-5, 10-11, February. 235. Mammals of northern Alaska. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 8:1-309, 1 colored frontispiece, 4 pis., 127 figs., March 10 (with J. W. Bee). 236. Animals that keep house below ground give nature a helping hand. Topeka Daily Capital, p. 13A, 1 fig., April 8 [essentially a reprint of no. 232 above, but without colored illustration]. 237. Remarks on mammalian ecology and germ warfare. Pp. 101-102, in Symposium on ecology of disease transmission in native mammals, 6 + 122 pp., July 6. 238. The biological relationships lietween American weasels (genus Mustela) and nematodes of the genus Skrjahingylus Petrov, 1927 (Nematoda: Metastrongylidae), the causitive organisms of certain lesions in weasel skulls. Revista Iberica de Parasitologia, Granada (Espafia). Tomo Extraordinario, pp. 531-576, 8 figs., August (with E. C. Dougherty). 239. Arctic to tropics in America. Proc. XIV Internat. Cong. Zool., Copenhagen, p. 125, December 31. 240. Speciation in American microtine rodents. Proc. XIV Internat. Cong. Zool., Copenhagen, pp. 160-162, December 31. 241. Systematics of American Lagomorpha. Proc. XIV Internat. Cong., Zool., Copenhagen, pp. 521-522, December 31. 1957 242. Kansas Natural Resources Conference. Spec. Rept., 82:15-19, April 1. 243. Museum of Natural History. An unpaged, illustrated "flier," Mus. Nat. Hist., Univ. Kansas, June 1 (with R. R. Moore). 22 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 244. Vernacular names for North American mammals north of Mexico. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 14:1-16, June 19 (with S. Anderson, J. K. Jones, Jr., and R. L. Packard). 245. [Functions of a museum of natinal history]. Pp. 108-110, in Cultural Leadership in the Great Plains — a report of the Great Plains Conference on Higher Education held at Univ. Oklahoma, Norman, P. G. Ruggiers (ed. ), Univ. Oklahoma Press, viii -|- 191 pp., about November 1. 1958 246. Teachers, conser\ation and native resources. Kansas Sportsman, 4(9): 4-5, 13, January 28. 1959 247. Introduction [Geographic distri]:)ution of contemporary organisms]. Publ. Amer. Assoc. Adv. Sci., 51:371-373, January 16. 248. Publications, University of Kansas Museum of Natural History. Pp. 1-4, February 7. 249. [Review of] A guide to Saskatchewan mammals. Blue Jay, 17:44, March. 250. The mammals of North America. Ronald Press Co., New York, l:x.xx -j- 546 + 79, and 2:ix + 547-1083 + 7.9), 1231 illustrations, March 31 (with K. R. Kelson). 251. Natural History Museum, University of Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 19:unpaged, illustrated "flier," May 29 (with R. R. Moore ) . 252. Additional evidence indicating that Sorex hijdrodromns Dobson is a mem- ber of the Sorex aicticus group of shrews. Pp. 263-265, lu Faima of the Aleutian Islands and Alaska Peninsula, bv O. J. Murie, N. Amer. Fauna, 61:xiv + 1-364, November 4. 1960 253. Conspecificity of two pocket mice, Perognathus goldmani and P. artus. Univ. Kansas Publ, Mus. Nat. Hist., 9:513-518, 1 map, January 14 (with M. B. Ogilvie). 254. Small carnivores from San Josecito Cave (Pleistocene), Nuevo Leon, Mexico. Univ. Kansas Publ, Mus. Nat. Hist., 9:531-538, 1 fig., January 14. 255. Elm spray peril: child safety [letter to the editor]. Lawrence Daily Journal- World, p. 4, January 14. 256. [Review of] A revision of American bats of the genera Euderma and Plecotus. Jour. Mamm., 41:144-145, February 20. 257. Publications, University of Kansas Museum of Natural History. Pp. 1-4, May 2 (with E. Hudson). 258. The red fig-eating bat Stenoderma rufiim Desmarest found alive in the West Indies. Mammalia, 24:65-67, 2 figs.. May 27 (with J. W. Bee). 259. A new subspecies of pocket gopher (Thomomys imibrinus) from Sinaloa, Mexico, with comments on T. u. sinaloae and T. u. evexus. Proc. Biol. Soc. Washington, 73:35-38, August 10 (witli C. A. Long). 260. Zoological subspecies of man. Mankind Quart., 1:113-119, 2 figs., October 31. 261. Oryzomys couesi only subspecifically different from the marsh rice rat, Oryzomys palustris. Southwestern Nat., 5:171-173, November 1. 262. ". . . Datna as the generic name of North American deer." Jour. Mamm., 41:537-538, November 11. 263. ". . . use of the generic name Si)cnnophihis F. Cuvier, 1825, for Mus citel- his Linnaeus and for other ground squirrels of the same genus." Jour. Mamm., 41:538-539, November 11 (with others). 264. Guide to the panorama of North American mammals. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 25:1-31, illustiated, December 15. DuRRANT — Hall Biography and Bibliography 23 1961 265. Degrees and titles. Science, 133:1630-1631, May 19. 266. Bisoi^ bison in Nevada. Jour. Mamm., 42:279-280, 1 fig.. May 20. 267. Rare liooks in scientific investigation. Books and Libraries at the Univer- sity of Kansas, 26:7-8, May 22. 268. A new species of mouse (Peromyscus) from northwestern Veracruz, Mex- ico. Proc. Biol. Soc. Washington, 74:203-205, August 11 (with T. Alvarez ) . 269. Prairie National Park. Trans. Kansas Acad. Sci., 64:265-266, November 1. 270. Dutch elm disease and DDT spray. Kansas State Biol. Surv., Service Leaf- let, no. 961-1-12, 1 p., December 15. 271. A new subspecies of pocket gopher (Heterogeomys) from northern Vera- cniz. An. Escuela Nac. Ciencias Biol., 10:121-122, December 20 (with T. Alvarez). 272. A new subspecies of black myotis (bat) from eastern Mexico. Univ. Kan- sas Publ., Mus. Nat. Hist., 14:69-72, 1 fig., December 29 (with T. Alvarez ) . 273. North American yellow bats, "Dasypterus," and a fist of the named lands of the genus Lasiurus Gray. Univ. Kansas Publ., Mus. Nat. Hist., 14: 73-98, 4 figs., December 29 (with J. K. Jones, Jr.). 1962 274. The Prairie National Park. Natl. Parks Mag., 36(173):4-8, 3 photographs, 2 figs., January 26. 275. Weasel. Encyclopedia Americana. 1962 ed., 28:532, March 15. 276. A new doglike carnivore, genus Cynarctus, from the Claredonian, Pliocene, of Texas. Univ. Kansas Publ., Mus. Nat. Hist., 14:135-138, 2 figs., April 30 (with W. W. Dalquest). 277. A new bat (Myotis) from Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 14:161-164, 1 fig.. May 21. 278. Collecting and preparing studv specimens of vertebrates. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 30:1-46, ,34 figs.. May 21. 279. [Review of] International Code of Zoological Nomenclature. Jour. Mamm., 43:284-286, May 29. 280. Natural History Museum, University of Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 31: unpaged, illustrated "flier," June 1 (with R. R. Moore ) . 281. Two methods for classifying Recent mammals as species or as subspecies. Symposium Theriologicum, Czechoslovak. Acad. Sci., Praha, pp. 147-152, June 30. 282. Preserving the prairie. Sierra Club Bull., 47(5):8, 2 photographs, July 12. 1963 283. ["Comments and recommendations" on Predator Control]. Defenders of Wildlife, Winter Bull., pp. 4-5, Feliruary 2. 284. Document 22/3 ". . . six (6) changes . . . [to] be made in the Code at the XVI International Congress." Bull. Zool. Nomenclature, 20:78, March 18. 285. The mammals of Veracruz. Univ. Kansas Publ., Mus. Nat. Hist, 14:165- 362, 2 figs.. May 20 (with W. W. Dalquest). 286. Statement at "Hearing before the Committee on Finance, United States Senate, eighty-eighth Congress, first session, on H. R. 1839 . . . tariff act ... to provide for the free importation of wild animals and wild birds. P. 35, July 23. 287. Introduction of exotic species of mannnals. Proc. XVI Internat. Cong. Zool., 1:267, August 20. 24 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 288. Introduction of exotic species of mammals. Quart. Bull. Defenders of Wildlife, pp. 6-7, October. 289. Opinions [on wildlife management]. Lawrence Daily Journal-World, pp. 1, 14, 3 illustrations, December 16. 290. Introduction of exotic species of mammals. Trans. Kansas Acad. Sci., 66:516-518, December 17. 1964 291. Natural History Museum, University of Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 35: unpaged, illustrated "flier," March 2 (with R. R. Moore ) . 1965 292. Some support for predators. Pacific Discovery, 18:31, 1 fig., January. 293. Government control programs and the red fox population. The Chronicle of the Horse, 28(47 ): 16-18, July 16. 294. Remarks. . . . XVI Internat. Cong., Zool., Scientific use of natural areas symposium. Field research projects, Natural Area Studies 2, pp. 8-11, October 15. 295. Names of species of North American mammals north of Mexico. Misc. Publ. Mus. Nat. Hist, Univ. Kansas, 43:1-16, December 10. 1966 296. What's wrong with South Dakota. Defenders of Wildlife News, 40(5) :1, January 12. 297. Annual Report, The State Biological Survey of Kansas, July 1, 1964 to June 30, 1965. Pp. 1-15, 5 figs., January 20 (with F. B. Cross of pp. 1-10; pp. 11-15 by F. B. Cross and B. A. Simco). 298. A plan for natural areas in Kansas. Trans. Kansas Acad. Sci., \ol. 69, pp. 1-10, June 15. (As one of many authors; a committee effort.) 299. [Statement on predatory mammals] at "Hearings before the Subcommittee on Fisheries and Wildlife Conservation of the Committee on Merchant Marine and Fisheries, House of Representatixes, eighty-ninth Congress, second session (serial no. 89-22). Pp. 89-127, 244-245, June 20. 300. The endangered black-footed ferret. Defenders of Wildlife News, 41:109, 1 fig., June 24. 301. [Statement on predatory mammals, Subcommittee on Fisheries and Wild- life Conservation, of the Committee on Merchant Marine and Fisheries, House of Representatives]. Defenders of Wildlife News, 41:152-156, June 24. 302. The pocket gopher in Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kan- sas, 44:1-32, 8 figs., October 26 (with J. F. Downhower). 303. [Review of] The wolves of Isle Royal. Natl. Parks Mag., 40:23, November 10. 304. Carnivores, sheep and public lands. Trans. 31st N. Amer. Wildlife and Natural Resources Conference, pp. 239-245, November 23. 305. [Review of| The elk of North America. Defenders of Wildlife News, 41:385, December 14. 1967 306. Two new species of bats. Genus Myotis, from Pleistocene Deposit in Texas. Amer. Midland Nat., 78:531-534, October 25 (with J. R. Choate). 1968 307. [Review of] The bats of West Africa. Jour. Mamm., 49:350-351, May 20. 308. [Review of] A place in the sun. Defenders of Wildlife News, 43:246, June 18. 309. A new subspecies of red fig-eating bat from Puerto Rico. Life Sci. Occas. Papers, Royal Ontario Mus., 11:1-5, 2 figs., July 22 (with J. R. Tamsitt). TAXONOMIC STATUS OF THE WOODRAT, NEOTOMA ALBIGULA, IN SOUTHERN CHIHUAHUA, MEXICO BY Sydney Anderson One of the earliest specimens of mammals known to have been preserved from the state of Chihuahua, Mexico, was a woodrat, Neotoma. It was obtained by Lt. D. N. Couch at Santa Rosaha, now known as Ciudad Camargo. The rat was reported by Baird (1859:44), who referred it to Neotoma micwptis, which he had described in 1855 on the basis of a specimen from Charco Escondido in Tamaulipas. The Chihuahuan specimen consists only of a mounted skin. When Goldman (1910) revised the genus Neotoma he assigned Couch's specimen (USNM 561), along with 50 other Chihuahuan specimens, to Neotoma alhigula albigula Hartley, 1894. Goldman recognized the species Neotoma micropus and mapped its range from Colorado and Kansas in the north to San Luis Potosi in the south and from the Gulf of Mexico west to the Rio Grande Valley in New Mexico and western Texas. He did not record it from Chihuahua. By 1910, Neotoma albigula and N. micropus each in- cluded several subspecies. The range of N. albigula lay mostly to the west of that of N. micropus but the two overlapped in parts of New Mexico, Texas, and Coahuila. These distributions were sum- marized by Hall and Kelson (1959). Baker (1956) studied Neo- toma in Coahuila and there recognized both species; however, he did not examine the 14 specimens from four localities from which Goldman had reported both rats. I recently wrote a key to include in a faunal report on Chihua- huan mammals. To my surprise specimens from southeastern Chi- huahua, presumably of the species Neotoma albigula, were identi- fied as Neotoma micropus when the key was used by non-mam- malogists. The faunal report has already been delayed by the search for answers to other taxonomic problems and I do not wish to digress again at length, but I will summarize the problem and give some conclusions. The subject would well repay additional study using morphological, distributional, and ecological evidence. Karyologi- (25) 26 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. cal, behavioral, serological, and other types of study in the growing methodological arsenal of taxonomy might also be productively employed. All specimens from Chihuahua currently assigned to the species N. alhigiila, except four specimens of Neotoma olbigiila melanura from the southwestern part of the state, are from the plateau east of the Sierra Madre. These rats may, on broad ecological grounds, be supposed to have come from a single population or at least a more or less continuously distributed and freely interbreeding series of local populations in similar habitats. Previous workers have assigned most of these rats to a single subspecies. There is no major ecological barrier in this area and the gaps that do occur in the known distribution are in places where little collecting has been done. However, contrary to what might reasonably be supposed, the rats on the plateau are not uniform in their morphological characteristics. After the discovery of micropm-\ike characteristics in two specimens from southeastern Chihuahua, I decided to look more critically at the other rats from that area. I found that many characteristics were involved, not just the one or two used in the key. The rats southeast of the Rio Conchos are morphologically intermediate as a population between typical N. a. albigida and N. micropus and they are, in some ways mentioned below, slightly closer to micropus. Among the previously reported features that distinguish IV. albigiila from N. micropus in Chihuahua and adjacent states are: (1) narrower mesopterygoid fossa (about 3.2 mm. or less rather than 4 or more), not broadly excavated near posterior plane of molars (Goldman, 1910:16); (2) relatively larger bullae; (3) color not pale slaty gray but usually darker and with a yellowish, brown- ish, or buffy hue; (4) smaller overall size, especially hind feet and diameter of tail (Bailey, 1932:171); (5) maxillo-vomerine notch present because medial plate of vomer not posteriorly extended (Finley, 1958:290); and (6) baculum having slender shaft and less massive base (Burt and Barkalow, 1942:290). This is not a com- plete list and is not documented with all relevant citations, but it does present the major differences. The meaning of these terms and the taxonomic problems posed will be clarified below. In New Mexico, Goldman (1910) recorded N. albigula from 11 of the 17 localities where N. micropus was recorded and he wrote nothing suggesting any difficulty of identification. In southeastern Colorado, N. albigula warreni and N. micropus canescens are sym- Anderson — Taxonomy of Chihuahuan Woodrats 27 patric, and some problems of identification were discovered there by Finley (1958), who conckided that certain specimens were probably hybrids. Baily (1932:171) noted that N. micropus "is easily distinguished" from N. alhigula in New Mexico, and James S. Findley informs me that he has had no difficulty distinguishing the two species in his years of work in that state. In northern Chihuahua three specimens with skins and skulls and two partial skulls from owl pellets seem clearly referrable to N. micropus. Four localities are represented and from three of these localities specimens of N. alhigula were also obtained. Prior to learning of the problem discussed here, I examined and identified 233 Neotoma alhigula from the plateau of Chihuahua in various museums. Most of this material has not been restudied and the specimens are not here listed. The specimens were probably correctly distinguished from two other species of Neotoma in Chihuahua. These are N. mexicana, which inhabits the Sierra Madre (where N. alhigula is absent) as well as adjacent parts of the range of N. alhigula, and N. goldmani, which is sympatric with N. alhigula in southeastern Chihuahua. The only other species of Neotoma in Chihuahua is N. micropus, discussed below. All Chi- huahuan records of N. alhigula and N. micropus are mapped in Figure 1. Representative Chihuahuan specimens and some from other areas were selected for study or restudy. These are listed below. In addition to these, a larger number of other specimens were reexamined cursorily in connection with specific questions as they arose at The University of Kansas (KU), The American Museum of Natural History (AMNH), and the United States National Museum (USNM), including the U.S. Biological Survey collection. Lists of Specimens Not all specimens examined are here listed, but all those from Chihuahua will be listed in a later publication. Three selected groups of specimens are listed below. Localities of the specimens plotted in Figure 4 and used in the factor analysis are as follows. — Neotoma alhigula alhi^uhi (all Chihuahuan, all KU); Ojo Palomo Viejo, 73911, 73915, 73916; Vado de Fusiles, 79693, 79696, 79699, 79703, 79705; 3.5 mi. N and 1 mi. W San Francisco, 69991; 1 mi. E Samala- yuca, 74366; 4 mi. NW Chihuahua City, 69994; 20 mi. N Cuahtemoc, 83369. Neotoma alhigula durangae (all except the first are Chihuahuan and at KU); San Gabriel (Durango), AMNH 21185 (the holotype of duran- cc UJ I- Q. O C/1 3 — (D (ED Ov N. a. durangae N. 0- albigula N. micropus 19 20 21 22 23 24 ANTERIOR ZYGOMATIC BREADTH 25 Fig. 4. Graph of two cranial measurements of individuals of three taxa of Neotoma as labelled. When series of N. a. albigula (]2 from near San Francisco) and N. a. durangae (seven from the Sierra Ahnagre) were compared, using means of 30 measurements, the differences were significant (P<0.05, Student's f-test) in 11 cranial measurements and in the length of the ear. The means of the former sample were less than those of the latter in all of these measurements except the alveolar length of the maxillary toothrow. The sample oi N. a. albigula from the Rancho San Francisco and the sample of N. a. durangae from the Sierra Almagre were then compared with a sample of N. micropus, again using the 95 per cent confidence level in the Student's t-test to compare means. Two or three significant differences among 30 measurements had been detected in the comparisons of samples within each of the two sub- species of N. albigula, and 11 significant differences were present between samples of the two subspecies. Further comparisons then revealed eight significant difi^erences between N. micropus and N. a. durangae and 15 differences between N. micropus and N. a. albigula. In terms of these data N. a. durangae is nearer to N. micropus than to N. a. albigula, and the possibility is raised that durangae may have been assigned to the wrong species. Other possibilities must also be considered. Could durangae be a population of inter- grades and there be only one species rather than two? Could the Anderson — Taxonomy of Chihuahuan Woodrats 35 large numbers of significant differences among the 30 measurements reflect nothing more than a general diflerence in size? Could the 30 measurements be largely irrelevant because diagnostic features were not adequately represented? Testing of these hypotheses and others requires either new evidence or new analysis of existing evi- dence, or both. To further compare Chihuahuan samples of N. alhigiila, the method of analysis described by Lidicker ( f962:164) was employed. The same samples mentioned above from the vicinity of five locali- ties in Chihuahua were used — San Francisco (A) and Ojo Palomo Viejo (B), both in northern Chihuahua, and Sierra Almagre (C), Parral (D), and Escalon (E) in the southern part of the state. Cranial dimensions and external measurements were used, and the "minimum significant difference" was twice the sum of the calcu- lated standard errors of the means for the two samples, rather than the estimate used by Lidicker. Only measurements significantly different at the 95 per cent level as shown by the Student's f-test were considered. Color was not used. Sample A was compared with B, C, and D; B with C; C with D and E; and D with E. The "Total Differentiation" and "Index of Differentiation" taken together as graphically shown by Lidicker (op. c/f.:165) were low on his scale. The rank on his nine unit scale was in the lower two units in comparisons between the two samples \\'ithin northern Chihuahua and among the three samples \\'ithin southern Chihuahua. The rank of the three comparisons between northern and southern samples was in the third unit of Lidicker's scale. The relatively greater difference, already noted above, between N. a. aJbigida (the northern samples) and N. a. diirangae (the southern samples) than between samples within either subspecies is again shown. Of the 29 measurements ( a thirtieth, length of ear, was not used here) in which differences might have occurred, only 14 were significantly different in at least one pair of samples. As pre\'iously noted, only two dimensions differed between samples of N. a. diimngae, and three between the two samples of N. a. aJbigida. Thirteen measurements were involved in the 25 differences found in inter-subspecies comparisons of samples, which indicates some concordance. Some of the 30 measurements taken are relevant to tliree of the six reportedly diagnostic characters. Size in general influences most measurements. Two measurements of the bullae are included, and the breadth of the mesopterygoid fossa is included. 36 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. I examined single measurements or pairs of measurements and found that N. aJbigida albigido could be distinguished from N. micropus with considerable success. Then I attempted to decide which of these two taxa was phenetically nearest to N. a. durangae. This was less successful because dumngae was inter)nediate between N. a. alhigida and iV. micropus in all characters individually exam- ined. I drew two-dimensional graphs of the most diagnostic meas- urements. The intermediacy of N. a. durangae and its partial over- lap with both N. a. alhigida and IV. micropus was always evident (see Fig. 4, for example). Further analysis seemed advisable. Factor Analysis Certain methods of multivariate analysis are useful in attempting to understand situations such as the present one in which a number of more or less correlated variables are involved. Factor analysis is one such method, in which a large number of correlated variables are reduced to a smaller number of uncorre- lated variables. The correlated variables are the measurements. The uncorrelated variables are the "factors." These are abstract hypothetical components, which then need interpretation in bio- logical terms. For those who want to see some other recent biological uses of factor analysis, the following are of interest: Gould (1967) on the evolution of pelycosaurs; Wallace and Bader (1967) on dentitions of Mus\ Brown et at. (1965) on human cranial proportions; and Lawrence and Bossert ( 1967 ) on species of canids A set of data was subjected to factor analysis by D. Vincent Manson using his Multivariate Statistical (MUST) program (Man- son, 1967). Computation required three minutes on an IBM 7094 computer. The data matrix consisted of 25 cranial measurements of each of 36 individuals — 12 N. a. alhigula from several locahties in northwestern Chihuahua, 13 N. a. durangae from several localities in southeastern Chihuahua and Durango (one specimen only, the holotype of N. a. durangae), and UN. micropus from several localities in New Mexico and Texas. The first factor, which may be termed the "rat factor," was dominant in all specimens. It shows a clear general homogeneity in the measurements of the mixed sample of skulls but is of no use in discriminating among the subgroups. The second and third fac- tors, however, are useful for this purpose, and, in fact, provide (Fig. 5) a better separation of the three subsamples than any Anderson — Taxonomy of Chihuahuan Woodrats 37 CNJ cr o .03 .02 .01 o < .00 -.01 -.02 \ N. micropus •^ 20O FACTOR 3 Fig. 5. Graph showing relationships of individuals of Neotoma as represented by hvo factors for each specimen. Unnumbered symbols represent specimens used in the original factor analysis. Numbered symbols are of additional specimens for comparison as described in te.xt. Encircling lines are drawn by eye to make it easier to see the distributions of the original specimens of the three taxa labeled on the graph. Symbols identify all except three specimens. These three are 14 and 15 (Neotoma albif^tila leucodon), and 16 (Neotoma albigula melanura). simpler subset of data such as the graph in Figure 4. The inter- mediacy of N. a. dtirangae and its overlap with N. a. albigula and N. micropus were previously surmised and these remain evident. The factor analvsis thus extended and refined the earlier results. The interpretation of factors 2 and 3 is facilitated on examination of the matrix of factor components ( Table 1 shows the composition of the factors in terms of proportional contribution of each of the 25 cranial measurements). For example, the measurements with greater absolute component values for factor 2 are those that will best serve to distinguish IV. micropus from N. a. albigula, and they thus provide a comparison with diagnostic measurements previously 38 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 1. — Factor components for first three factors and 25 measure- ments (listed by letter as in text). Factor 1 Factor 2 Factor 3 Measurement components components components A 0.08722 0.01964 0.04011 B 0.10493 0.17303 0.09230 C 0.09293 —0.34159 0.00964 D 0.15819 0.08160 0.24123 E 0.11445 0.20428 —0.02983 F 0.51629 0.06707 0.13103 G 0.03879 0.35224 0.19642 H 0.03628 0.07745 0.05867 I 0.08381 0.04383 0.00168 J 0.09223 0.12933 0.06402 K 0.03251 0.04122 0.00121 L 0.14823 —0.02236 0.44917 M 0.26318 0.47117 0.12678 N 0.28885 0.38384 0.21413 O 0.08443 0.02250 0.28622 P 0.03001 0.14832 0.28972 Q 0.54472 0.16662 —0.15326 R 0.19234 0.05768 0.48463 S 0.17175 0.02826 0.14695 T 0.07060 0.12556 0.16935 U 0.21438 0.40223 0.33691 V 0.06039 0.16584 0.06192 W 0.06960 0.13902 0.06171 X 0.20122 —0.03247 0.07969 Y 0.05319 0.00249 0.04169 ascertained by other methods. Diagnostically, the best five measure- ments for factor 2 (factor components given in Table 1) are anterior zygomatic breadth, mesopterygoid breadth, posterior 2ygo- matic breadth, breadth of the braincase, and length of the palate. Proportional differences involving these measurements are implied, because absolute size as such was eliminated in the analysis by normalizing the row (or specimen) vectors. There are, of course, mean differences in absolute size between the three subsamples. These differences were readily evaluated by comparing the sums of squares for the normalized data matri.x in the computer output or are evident in the data of Table 2. IV. microptis is largest and N. a. durongae is intermediate. There is some oxerlap between N. mi- cropus and N. a. alhi^uh. Some of this overlap results from the inclusion of rats of different ages in the samples. All were "adults" but differences in size, toothwear, and amount of fusion between cranial elements all suggest that were larger series available the range of inferred ages or relatixe ages in the selected sample of "adults" could be justifiably reduced further. Factor 3 suggests that IV. a. diirangae tends to have some char- acteristics in which it differs from both N. a. alhigula and N. mi- Anderson — Taxonomy of Chihuahuan Woodrats 39 cropus, but the tendency is weak. The subsample of N. a. durangae has higher factor coefficients on the a\'erage for factor 3 than do N. micropus or N. a. albigula. The most important measurements (those with larger factor components as shown in Table 1) con- tributing to factor 3 are length of nasal bones, exoccipital breadth, and breadth of braincase, which as akeady noted also contributes importantly to factor 2. The way in which these three measure- ments contribute to distinguishing N. a. durangae from IV. a. albig- ida and N. micropus is not visualized simply. The measurements cannot be used singly or in pairs to distinguish individuals of N. a. durangae from those of the other two kinds. The tendency for uniqueness in N. a. durangae among the three kinds is much less than the tendency for intermediacy shown in many individual measurements and in factor 2. The two measurements of the auditory bullae have low factor components for all three factors. The alleged usefulness of bullar size is therefore not verified. Factor analysis in this case contributes the following: it verifies the usefulness of most of the previously suggested diagnostic char- acters; it discounts the usefulness of bullar size; it indicates that the intermediacy of N. a. durangae involves much more than size alone. The measurements that are shown to be most useful by factor analy- sis are, in general, those regularly used by systematic mammalogists, and the measurements not often used are shown to be less im- portant for diagnostic purposes. This is not an argument for con- ventionality or against a careful search for useful new characters, but it does indicate that seemingly "subjective" methods are some- times "objectively" verifiable. A new specimen may be compared with the results of the present factor analysis, as follows: record the 25 measurements described; obtain the sum of the squares of these measurements and extract its square root; take the first measurement, di\'ide it by the square root noted, and multiply the quotient by the appropriate factor com- ponent measurement (for example the first value in the column for factor 2 in Table 1); do the same for each measurement in turn and sum the 25 products. This sum is the value to be plotted (for factor 2) as in Figure 5. The process is repeated using the components for another factor (for example factor 3 if comparison is to be made with factor 2 as in Fig. 5 ) . The process is not overly cumbersome if a desk calculator is available. A program has been written for the 40 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Programma 101 Computer (Olivetti-Underwood) and will be sent upon request. The information summarized to this point answers certain ques- tions about structural resemblances but does not answer some other interesting questions. For example, are one or two species involved? Three areas where we should look for answers are as follows. Firstly, specimens from localities in Chihuahua between the localities al- ready represented should be studied to learn whether intergradation occurs between N. a. albigtda and N. a. durangae, and whether the zone of such intergradation, if present, is narrow or broad ( discussed below ) . Intergradation is only one possibility ( or hypothesis ) to be tested. I interpret the available evidence to suggest intergradation between N. a. aJbigula and N. a. durangoe in Chihuahua. Five specimens especially relevant to this question are numbers 11, 12, 13, 17, and 22 in Figure 5. The first three of these are from south of the Rio Conchos and are assigned to N. a. dtirangae. The last two are from north of the Rio Conchos and are assigned to N. a. albigula, but these specimens are not from localities near the river. No data are at hand for specimens from north of the river and nearer to it than the two mentioned above ( and one other included in the orig- inal sample of N. a. albigula). Study of series from the two banks of the ri\'er, if they were a\'ailable, would be interesting. Secondly, other characters could be studied. Color and bacular characters have been studied and ^^'ill be discussed below. Thirdly, specimens from other parts of the ranges of N. albigula and N. micropus should be studied. An especially relevant area lies east of Chihuahua. Special attention should be given to what hap- pens distributionally, ecologically, and morphologically in eastern Coahuila where the two species are said to meet. My deliberately limited studies in that direction are as follows. I examined specimens at The University of Kansas from Coa- huila assigned by Baker (1956:281) to N. a. albigula. They may better be referred to what I am here calling N. a. durangae. Al- though I have not studied the three specimens from Durango reported by Baker and Greer (1962:126) as N. a. albigula, I judge on geographic grounds that they also should be referred to N. a. durangae. Goldman (1910) referred specimens from Saltillo, Coahuila, to N. albigula leucodon (USNM 117166, 117167) and N. iiucropus micropus ( USNM 117168) . The first two are younger than the third but none is in juvenile pelage. Pelages of all are similar in color. Anderson — Taxonomy of Chihuahuan Woodrats 41 Table 2. — Measurements in millimeters of samples of three taxa of Neoioma. Measurements are explained in tfxt; specimens in each sam- ple ARE ALSO LISTED IN TEXT. MeAN, STANDARD DEVIATION, MINIMUM, MAXI- MUM, AND SAMPLE SIZE ARE GIVEN. N. albi^ula albigula N. albigula durangac N. micro inis A (length of bulla) 6.65+0.38 6.15-7.2.5 11=12 B (molor toothrow) 8.50±0.29 7.95-8.8 n=12 C (length of palate) 7.34±0.25 6.8-7.85 n=12 D (zygomatic aperture) 12.60±0.36 11.95-13.05 n=12 E (incisive foramen) 9.03±0.46 8.1-9.5 n=12 F ( condyloincisi\'e length) 40.68±0.79 39.4-41.7 n=12 G ( mesopterygoid breadth) 2.75±0.29 2.2-3.2 n=12 H (breadth of palate) 2.78±0.28 2.2-3.1 n=12 1 (postdental breadth) 6.58±0.18 6.2-6.8 n=12 1 ( rostral breadth ) 7.24±0.28 6.9-7.9 n=12 K (breadth of Ml) 2.61±0.17 2.25-2.9 n=12 L (exoccipital breadth) 11. 64 ±0.63 10.4-12.8 n=ll M (anterior zygomatic breadth) N (posterior zygomatic breadth) O (occipitoparietal length) P ( nasopremaxillary difference) .— 20.42+0.63 19.2-21.2 n=12 22.48±0.85 20.4-23.8 n=12 6.71 ±0.47 5.65-7.3 n=12 2.32±0.37 1.8-2.9 n=12 7.20±0.46 6.6-8.0 n=7 8.14±0.39 7.7-8.75 n=7 7.81 ±0.65 7.15-9.1 n=7 12.62±0.94 11.5-14.0 n=7 9.16±0.84 7.6-J0.3 n=7 41.96±1.36 40.3-44.35 n=7 3.30±0.26 2.9-3.6 n=7 3.06±0.46 2.4-3.7 n=7 6.60±0.22 6.2-6.8 n=7 7.81±0.39 7.5-8.2 n=7 2.60±0.25 2.3-2.8 n=7 12.54±0.92 11.4-14.2 n=7 21.41±1.30 19.9-21.7 n=7 23.34±0.95 22.1-24.7 n=7 6.93±0.81 6.1-8.3 n=7 2.89±0.30 2.5-3.3 n=7 7.25±0.32 6.7-7.85 n=12 8.76±0.59 7.7-9.3 n=12 7.20±0.65 6.3-S.l n=12 13.53±0.76 12.1-14.6 n=12 10.05±0.60 9.1-11.0 n=12 43.32±2.30 .38.6-45.65 n=12 3. 99 ±0.46 3.4-4.8 n=12 3.22±0.32 2.8-3.6 n=12 7.33±0.39 6.9-8.2 n=12 7.54±0.65 6.6-8.5 n=12 2.69±0.17 2.45-3.05 n=12 12.40±0.73 11.4-13.9 n=12 22.82±1.41 20.2-24.9 n=12 24.88±1.44 21.8-27.1 n=12 7.28±0.80 5.85-8.3 n=12 2.14±0.49 1.4-2.9 n=12 42 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 2. — Continued. N. albigiila N. albigtila albigula durangae N. micropiis Q (occinitonasal length) 43.32±1.19 43.88+1.72 45.80±2.31 41.6-45.0 41.55-46.65 41.1-47.15 n=12 n=7 n=12 R (length of nasals) 15.02+0.67 15.31+0.69 16.29+1.13 13.8-16.05 14.35-16.45 14.6-18.2 ni=12 11=7 n=12 S (rostral length) 13.37+0.57 13.80+0.81 14.51 + 1.06 12.3-14.05 12.85-15.0 12.6-16.3 n=12 n=7 n=12 T (interorbital breadth) 5.76±0.19 6.06+0.39 5.95+0.46 5.4-6.0 5.5-6.7 5.3-7.0 n=12 n=:7 n=12 U (breadth of braincase) 17.76+0.47 17.86+0.61 17.60+0.63 17.1-18.6 17.2-18.7 16.7-19.1 n=12 n=7 n=12 V (incisive projection) 4.39+0.44 5.15+0.34 5.26+0.56 3.3-5.1 4.8-5.75 4.7-5.95 n=12 n=7 n=12 W (depth of bulla) 5.28+0.26 5.96+0.56 5.62+0.24 4.9-5.6 5.4-7.0 5.3-6.1 n=12 n=6 n=12 X (depth of sbill) 15.55+0.73 16.37+0.67 16.89±0.79 13.85-16.75 15.7-17.25 15.2-18.25 n=12 n=6 n=12 Y (breadth of zygomatic plate) .... 4.19+0.20 4.32+0.51 4.53+0.32 3.9-4.6 3.9-5.25 4.2-4.95 n=12 n=7 n=12 Total length ..- 320.5+12.0 331.4+7.2 332.7±12.8 305-340 321-341 315-348 n=10 n=5 n=7 Length of tail 142.8+9.0 150.0+3.1 139.0+8.8 131-160 145-153 130-153 n=10 n=5 n=7 Length of hind foot 32.8+1.9 33.4+1.9 35.0+2.7 30-35 30-36 30-39 n=9 n=7 n=7 Weight 176.6+18.2 197.7+30.1 245+52.4 155-209 153-245 191.4-296 n=10 n=7 n=3 all having a yellowish hue. No. 117168 has a darker dorsal tail stripe than the others, and no. 117167 has larger hind feet (36 mm. as opposed to 33). I judge that a single species is represented. The specimens seem more al])i(i,tila-\ike than micropus-\ike. Eight speci- mens from Monclova, Coahuila, include one (USNM 117018) re- ferred by Goldman to N. alhiii^ula albigula and seven (USNM 117017, 117019-117021, 117169-117171) referred by him to N. mi- cropiis canescens. Two of the seven are young and their skulls are damaged. Measurements were taken of the other six from Mon- Anderson — Taxonomy of Chihuahuan Woodrats 43 clova for comparison \\'ith the results of the factor analysis already done. On the basis of yellow hue of pelage, smaller size, and nar- rower mesopterygoid fossa I am inclined to place 117017 and 117019 \\ith 117018. The condition of the vomer posteriorly does not help to separate specimens in the series from Monclova. I also measured a specimen from Jimulco, Coahuila (USNM 58072, a large male referred to N. olbigula albigula by Goldman), and one from the northern boundary of Chihuahua (USNM 35551, a N. micropus of moderate size). I have not examined the three specimens from Jaral, Coahuila, the only other Coahuilan locality of sympatry re- ferred to by Goldman for the species N. dhigula (two specimens) and A^ micropus (one specimen). The coordinates for factors 2 and 3 were calculated for addi- tional specimens measured and are plotted in Figure 5, for com- parison with the series used in the original analysis. The additional specimen of N. micropus from northern Chihuahua falls with the other N. micropus but in the area of overlap with N. a. durangae. The rat from Saltillo and the one from Jimulco fall with N. a. durangae. The two rats from Monclova, re-identified by me as N. a. durangae, fall with other members of that subspecies. Two of the three rats from Monclova identified by both Goldman and me as N. micropus fall within the area of overlap of N. micropus and N. a. durangae. However, the third falls \\ath N. a. durangae and outside the area on the graph of N. micropus. The uncertainties evident in ( 1 ) my own attempts to identify these rats from the alleged locality of sympatry, ( 2 ) the differences in assignment of some individuals by Goldman, by me somewhat subjectively, and by the factor analy- sis of cranial measurements alone, and ( 3 ) the lack of clear bimodal clustering in the Monclova sample all suggest, although they do not prove, that only one taxon is present in the sample from Monclova, Coahuila. In short, to summarize the Coahuilan situation, more work is needed. There is no locality of certain sympatry between two taxa, although the small sample from Monclova is suggestive. As my study has proceeded, my confidence in the existence of a species boundary between N. albigula and N. micropus as now known, or at least in my ability to define the boundary, has decreased. If they behave as species in eastern Coahuila, the difference between the two species is certainly less than between these two species where they are sympatric in northern Chihuahua and adjacent regions of New Mexico and west Texas. 44 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Discriminant Analysis Cranial measurements of the original 36 specimens used in the factor analysis and of 22 additional specimens ( the same plotted in Fig. 5 and listed in text) were examined by Discriminant Analysis (five minutes on IBM 7094 computer). The three original groups were used to derive the discriminant functions, except that one specimen of N. a. durangae was placed with the N. micropus by mistake. The three groups were well separated, including the three specimens of N. a. durangae that were not separated by the factor analysis as shown in Figure 5. The mistakenly-placed specimen of N. a. durangae appeared with the cluster of N. micropus in the analysis, but at the side of the cluster nearest that of durangae. The factor analysis uses all measurements and incidentally results in a scatter in which groups may be separated or partly separated. In discriminant analysis only the differences in measurements between specified groups are used. This enhances the separation of groups. Plotting of the additional 22 specimens in terms of discriminant functions places them in scattered positions about or between the three discriminant groups, but their general relative positions are consistent with the relationships otherwise found. The discriminant analysis tends to separate N. micropus more clearly from N. a. albigula and N. a. durangae than did the factor analysis. Both analyses tend to place additional specimens of N. micropus (nos. 1-4 in Fig. 5) with others of that species, and to place additional specimens of N. alhigula (nos. 13, 15, and 16 in Fig. 5), which are of subspecies other than those already studied, with the specimens of that species ah'eady studied. This technique is still being developed and evaluated, and, there- fore, more detailed comments on these results are not included. Color Color is notoriously more difficult to describe or report on than are measurements to which numerical values easily can be assigned. I have mentioned that N. micropus canescens, the widely distributed subspecies that meets N. albigula in the Chihuahuan region, differs from N. albigula albigula in grayness, paleness, and relative lack of yellowish or buffy hues in dorsal pelage. However, there is consid- erable variation in color \\'ithin the wide range of N. a. albigula even after its reduction by the present reassignment of specimens south of the Rio Conchos of Chihuahua to N. a. durangae. There are specimens of N. a. durangae that are not distinguishable by color Anderson — Taxonomy of Chiiiuahuan Woodrats 45 from many N. a. albigula from Chihuahua. However, on the average N. a. durangae is grayer and paler than N. a. albigida. The palest specimens examined of N. a. durangae are from Escalon. The single specimen of N. a. durangae that falls in the midst of the N. a. alhigtda in Figure 5 is from Escalon. It therefore resembles N. a. alhigtda cranially and resembles N. micropus in color. When only one or two cranial characters and color, which is known to be subject to strong local natural selection, were found to be intermedi- ate in N. a. durangae, it seemed reasonable to suggest that selection might have produced a convergence in these few characteristics. However, evidence for intermediacy has accumulated, and a large number of characters are involved. Some of these are not struc- turally related, are poorly correlated (when individuals in a single series are compared), and are not obviously influenced by local selection. Convergence as a result of selection is less reasonable than the alternative interpretation that these animals have the com- plex suite of characters because of common ancestry. The interest- ing question now becomes whether genetic exchange is occurring anywhere in nature between N. micropus and N. albigida, and, if so, what form the exchange takes. Does free inter gradation occur, or occasional hybridization, or do different events occur at different places? Baculum The structure of the male phallus, and of the baculum therein in particular, has been studied for Neotoma albigida and Neotoma micropus by Burt and Barkalow (1942) and by Hooper (1960). These authors suggested that N. albigula differs from N. micropus in (1) slenderness of shaft, (2) shallower U-shape of base, (3) larger distal knob, (4) smaller glans, (5) terminal hood relatively larger and not cleft distally, as opposed to slightly cleft, (6) bone longer and its spine shorter relative to both glans and foot lengths. The first three differences were based on study of 15 albigida and four micropus by Burt and Barkalow. In their table of measure- ments the range for micropus is within that of albigula for length and base measurements (both dorsoventral and lateral) but near the middle of the shaft there is little overlap in dorsoventral di- ameter and none in lateral diameter (0.51 to 0.73 for albigula, and 0.80 to 0.91 for micropus). Hooper examined three specimens each of albigula and micropus and one of Neotoma floridana and noted that the three species are so similar as to suggest that they are con- 46 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. LU h- < > O Ll O Q. LlI Q mm. 1 1 1 1 1 1 i_ ■ 1 /5^^ <^ 1 - 0.6 - //-^ O / 7 / ~ fo o/(3 0.4 1° O y - W- 1 1 1 1 1 (o o) - 1 1 1 0.4 06 0.8 10 "1^- WIDTH OF BACULUM AT MlD-POINT Fig. 6. Graph of two measurements of the bacula of individuals of tliree taxa of Neotoma. Large open circles are N. alhigula albigitla; dots are N. a. diirangae; small open circles are N. micropus. Encircling lines are drawn freehand simply to aid perception of the groups. As in Figures 4 and 5, durangae is intermediate to the other two taxa. Specific or are sibling species. Differences 4 through 6 as Hsted above were said to be shght (Hooper, 1960:5) and I have not attempted to study them in my material. Series of bacula were selected for study and comparison as fol- lows: N. albigtda alhigula (22), N. albigitla durangae (16), and N. micropus (13). Eighteen were measured, and their values for two measurements are plotted in Figure 6. These are the two meas- urements of the six taken that best distinguish N. a. alhigula from N. micropus and which therefore are most revealing as to the posi- tion of N. a. durangae. As in the cranial characters, in color, and in size of entire animal, bacular characters show intermediacy for N. a. durangae, and are not clearly nearer either N. a. alhigula or N. micropus. Structure of Vomer The degree of development and form of the vomer differ in different taxa of Neotoma. Finley (1958) described the differences between the species N. alhigula (as represented by the subspecies N. a. icarreni) and N. micropus (represented by N. m. canescens), and he used these characters in evaluating evidence for species hybridization that he found in southeastern Colorado. Figure 7 illustrates the stages of development. The major variable is the degree of enlargement posteriorly of the medial vomerine plate ( shown stippled ) . In the least developed stage ( as in 7B ) , a distinct Anderson — Taxonomy of Chihuahuan Woodrats 47 Fig. 7. Drawings of vomer and sinrounding elements in skulls of Neotoma. A — dissection from the right to a sagittal plane near the middle of skull but leaving the medial partitions of ethmoid, cartilage, and vomer intact. Labelled elements are: be, braincase; ca, cartilage; et, ethmoid; fr, frontal; ma, maxillary; ?ia, nasal; pin, premaxillary; ps, presphenoid; and vo, vomer. Cut elements are shown liy diagonal lines, and the vomerine partition is stippled for ease of comparison with B, C, D, and E. These are diagrams showing four states of vomerine dexelopment arranged in morphological sequence from least developed to most developed. States in the range of B and C occur in N. albigula alhigiila, those in the range of C and D occur in N. albigula durangae, and those in the range of D and E occur in N. micropus: An oblique view looking dorsally and slightly posteriorly into the incisive foramina is shown in F and H, which correspond in state to B and D, respectively. The oblique orientation of skull in F and H is shown by G. 48 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. rounded opening is apparent in the medial plane as seen in the incisi\'e foramen (as in 7F). When the plate is larger, conditions such as in 7C, 7D, and 7E are evident. The legend for Figure 7 provides other details. A condition in Neoto7na pakitina that exceeds that of Figure 7E was kindly pointed out to me by Professor E. R. Hall, who is study- ing the taxonomic status of this species. In some of the specimens that he has assembled at The University of Kansas the posterior projection of the vomer is so great that it protrudes visibly behind the posterior palatal margin (to the position of the letter E in Fig. 7E). Certain modifications in adjacent structures are positively cor- related with degree of vomerine enlargement: (1) shortness of medial maxillary spine; (2) shortness or loss of articulation of this spine with premaxillary; (3) amount of contact of spine with vomer, at least in stages such as 7C and 7D, although in some specimens a slit may separate these elements (as in 7E); (4) shortening of medial slit between the presphenoid and medial part of vomer and bordered laterally by posterolateral wings of vomer ( the opening is reduced in a form such as 7E to a posteriorly directed median opening); and (5) narrowing of maxillo- vomerine gap posteroven- tral to median part of vomer from a broadly rounded aperture to a narrow slit. In this complex of related characters, as in all other diagnostic characters studied, N. a. chirangae is intermediate between iV. albigula albigula and N. micropus. Discussion I judge it unwise to synonymize N. aUngula and N. micropus on the basis of available information, although the contrary conclusion is based on tenuous evidence. The basic questions about species limits cannot be resolved without additional information from the field. Nomenclatorially, I think the conservative course is to use the names as presently arranged until better evidence is available. A change at this time would add nothing to our knowledge and would not be especially useful. There is, furthermore, a possibility that not only is N. albigula synonymous with N. micropus. but that they are both conspecific and hence synonymous at the species level with N. floridami. If this be so, the name of the species would become N. fioridana, for that is the oldest name among these three. The relationships of N. micropus and N. fioridana are currently being Anderson — Taxonomy of Chihuahuan Woodrats 49 studied by Elmer C. Birney at The University of Kansas and perhaps by other students elsewhere. In any case, N. fioridana, N. micropus, and N. olbigula, as suggested by previous authors, are certainly closely related. The following are hypotheses for later consideration. N. alhimoiiiys talpoides Northern pocket gopher PcioDiysctis maniculatus .._ Deer mouse Clcthrionomijs gapperi Red-backed vole Plienacomijs intermedins Heather vole Microtns 7nontanns Montane vole Microtns longicaudus Long-tailed vole Zapns princeps Meadow jumping mouse Cants latrans Coyote Vulpes vnlpes Red fox Martes americana Marten Mustcla crminea Ermine Mustela frenata Long-tailed weasel Cervns canadensis American elk Odocoiletis hemionus Mule deer the traps, such as shrews, seemed eventually to contact the copper wire, the quadrats seemed at the least to provide reliable indices to the abundance of small mammals. Pocket gophers were common in the stiidy area, and because these rodents are fossorial it would be expected that they would regularly pass beneath the fence, making accurate estimates of their density impossible. It seemed, how- ever, that pocket gophers were as xidnerable to the wire as were other rodents. When the quadrats were established a strip about six inches wide beneatli the wire was completely cleared of vegetation, and usually about one inch of soil was remo\ed with the \egetation. This cleared strip offered a strong attraction to pocket gophers; repeatedly they tunneled to the surface in the strip and were killed by the wire. The direction from which they came could be deter- mined by tracing their burrows. Due to the attraction offered by the cleared strip, a good indication was obtained of pocket gophers moving in or out of the quadrat, and the estimates of their population densities made within the quadrats were, in my judgment, reasonably accurate. A series of quadrats was established four times in 1965, four times in 1966, and three times in 1967. Each series consisted of four half-acre quadrats. In each of tlie first two summers, therefore, a total of eight acres was sampled, and in the third summer six acres were studied. Because of adverse weather condi- tions and late snowmelts in two summers, only in 1966 were quadrats operated in June. In the other two years they were operated in early July. The first set of quadrats each summer was established as soon after snowmelt as possible. At this time most of the plants were just beginning their annual growth and the soil at many sites was still saturated with water. The last set of quadrats each summer was usually operated in early September, after the first late summer frosts, at a time when the annual growtli of most plants had been completed. An attempt was made to situate all quadrats in the same plant 54 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. community. Each set of quadrats was established at a different place in a given summer, but for a given set of quadrats the same sites were used each summer. A total of 1639 small mammals \\'ere taken during this study. Because the quadrats did not always yield adequate samples for reliable information on reproduction, additional trapping was done outside the quadrats and at a considerable distance from them. Animals were frozen in the field soon after captrne and were dissected later in the laboratory. The flora was studied by sampling the frequency of the plants in the census quadrats. One hundred randomly placed plots, each six inches square, were sampled each summer in each quadrat. Population Densities In each year of the study the population density of small mam- mals was low immediately after snowmelt and relatively high in late summer. Although this is probably the basic pattern of change that occurs in most summers, the relati\'e abundance of the species and the monthly changes in population densities of each species seem- ingly change sharply from year to year. Summer of 1965 Snowmelt was late in this summer due to an unusually deep winter snowpack and a cold spring. The first set of quadrats was not in operation until July 8, when the soil was still saturated with water and scattered snow drifts persisted in shaded situations; in most places the summer growth of vegetation was barely underway. An occasional dead M. montamis or T. tolpoides was found in places where water had coxered the surface of the ground for several weeks during snowmelt. The density of small mammals was low at this time (Figs. 1-2); the census quadrats indicated a density of 17.5 per acre. The four most abundant species and their densities per acre were: P. manicu- latiis, 7.5; E. minimus, 4.0; M. montanus, 3.0; T. falpoides, 2.5. Be- cause of the difficulty with which pocket gophers are trapped imme- diately after snowmelt, the figure for T. tolpoides is probably lower than was the actual density. Although the pattern of changes in density differed between species, by early September the density of small mammals had risen roughly three-fold to 51.0 per acre (Fig. 3). Densities were: T. talpoides, 14; E. minimus, 14; P. manicidatus, 6.5; S. vogrons, 6.0. The figures for E. minimus seem unreasonably high and should be considered as an index to abundance rather than an expression of actual density. On two occasions chipmunks were observed to leap onto the chicken wire fence enclosing a quad- Vaughan — Montane Small Mammal Fauna 55 10 8 • 1965 17.5/acre 6 4 ■ ■ 2 u < 10 UJ 8 6 • 1966 8.0/acre ^4 -2 ■ ■ LU Q 0 10 1967 34.0/acre 8 • 6 4 2 . r^ 1 Tt Em Pm Mm SPECIES Sv Sc Fig. 1. Early summer densities of six species as determined in four half-acre quadrats each summer. Quadrats were operated soon after snowmelt in June or early July. The following symbols are used: Tt, Thomomijs talpoides; Em, Eutamias minimus; Pm, Peromyscus maniciilatiis; Mm, Microtus montanus; Sv, Sorex vagrans; Sc, S. cinereus. rat and scramble over the fence without contacting the copper wire; the large number of chipmunks taken in the quadrats may have resulted in part from this type of entry. Usually, however, chipmunks attempted to enter or leave the quadrat by crawling beneath or through the fence; these animals were killed almost instantly when they contacted the copper wire. Additional indica- tion of the abundance of chipmunks in the study area in early Sep- tember of 1965 is indicated by the fact that the total number of 56 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 19 15 10 19 ^ 15 < 10 z UJ a 15 10 5 • Peromyscus Eutamias Thomomys Microtus 1967 QUADRATS Fig. 2. Changes in densities of some small mammals in summer. Quadrats were operated as follows: series 1, soon after snowmelt, in late June or early July; series 2, in mid- or late July; series 3, in August; series 4, in late August, or early September. chipmunks taken during operation of the fourth series of quadrats, including individuals killed trying to enter the quadrats, was 51. The ground remained mostly free of snow until mid-November. Trapping from November 4 to 7 revealed that both T. talpoides and P. maniculatus were common, but no M. montonus were taken. Chipmunks were apparently in hibernation, for none were seen or trapped. Summer of 1966 Snowmelt was fairly early in this summer and much of the study area was free of snow by about May 25. The first set of quadrats was in operation on June 15 and yielded 8.0 small mammals per acre (T. talpoides, 5.0; P. maniculatus, 2.0; E. minimus, 1.0). The last series of quadrats was established on September 2. The density Vaughan — Montane Small Mammal Fauna 57 15 . e 10 - 1965 51.0/acr 5 1 15 ■ . LU ■ 1966 < 33.5/acre TY PER CO 1 1 z lU ^15 ■ 1967 k 1 10 ■ 32.5/acrt 5 Tt Em Pm Mm SP Sv ECIE s Sc Fig. 3. Late summer densities of six species as determined in four half-acre quadrats each summer. Quadrats were operated in late August or early September, after the first late-summer frosts. Symbols for species are the same as in Fig. 1, but Zp, for Zapiis princeps, is also used. of small mammals was four times as great at this time (33.5 per acre) as it was in June (Figs. 1-3). The most abundant species and their densities were T. talpoides (13.5), P. manicuhius (10.5), and E. minimus (8.0). Summer of 1967 Snowmelt persisted through the first half of June and occasional snow fell through mid-June. Although the first set of quadrats were not studied in 1967, it was clear that the pattern of change in the density of small mammals that typified the previous two summers was at least partly reversed in 1967 (Figs. 1-3). The set of quadrats started on July 1 indicated a fairly dense population of 34 small 58 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. mammals per acre (P. manicukitus, 12.5; E. minimus, 11.5; T. tal- poides, 5.0; M. montamis, 5.0). In 1967, rather than a steady rise in density through late summer, as occurred in the other years, there was a decline by late August to 32.5 per acre. This was due largely to drops from July to late August in the densities of both P. manicii- latits (from 12.5 to 6.0) and E. minimus (from 11.5 to 5.5). Popu- lations were lower in late summer of 1967 than they were at com- parable times in either of the other years. Population Dynamics Sharp fluctuations in small mammal populations were seemingly the rule throughout the study. As shown in Figures 1 to 3, the relative densities and the absolute densities of the different species shifted markedly from summer to summer as well as from month to month within a summer. Early in the summer of 1965, for example, the most abundant species was P. manicuJatus; T. talpoides was fourth in terms of abundance. This relationship was altered two months later, when T. talpoides was the most abundant mam- mal. Whereas the density of Thomomys rose steadily during the summer, that of P. maniculatus was lower early in September than it was just after snowmclt. The summer of 1965 was unusually cool and rainy; perhaps this weather resulted in poor survival of young Peromyscus. In any case, the summer of 1966 presented a different picture. In early summer T. talpoides was the most abundant species with P. maniculatus second. Although the rate of increase was different in each species (Fig. 2), this order was maintained through early September. As a further difference between these two summers, M. montanus was taken commonly and consistently throughout the summer of 1965, but only one individual was taken in the quadrats in 1966. Densities of small mammals were generally low in 1967, but M. montanus was commoner late in that summer than at any other time in the study. The density of the entire com- munity of small mammals in late summer also fluctuated, being highest in 1965 (51 per acre), and roughly the same in 1966 and 1967 (33.5 per acre and 32.5 per acre, respectively). The period of dispersal of young of the year was signalled by the occasional capture at the quadrats, usually as the animals tried to enter, of species that did not regularly occur there and that prob- ably found optimal conditions in nearby moist situations. Species of this type were Microsorex hoyi, Phenacomys intermedins, and Vaughan — Montane Small Mammal Fauna 59 Zapiis princeps. Sorex cinereus, a species that was taken occasion- ally throughout the summer, was taken much more frequently in late summer. In nearby areas in Wyoming this species is known to favor moist habitats ( Brown, 1967 ) . Probably largely as a result of the dispersal of young animals, the greatest diversity of species was usually encountered in late summer. In the study area the population levels of small mammals were influenced strongly by the survival of young. In southern Colorado, Hansen (1962) found that high survival of young was associated with high densities of pocket gophers and low survival of young was associated with a declining population. Age ratios at the end of the breeding season, then, can be a partial basis for predictions of future densities. Limited data on age ratios of pocket gophers in the study area are relevant to a consideration of population fluctuations. Density of pocket gophers was high in late summer of 1965 ( 14 per acre) and survival of young, as indicated by the fact that 87 per cent of the 38 animals taken were young, was high. The density was about the same in late summer of 1966, but survival of young was probably low (50 per cent of 22 animals were young). Pocket gopher density declined in 1967 to but six per acre in late summer. This drop was perhaps due both to low survival of young the previ- ous summer and to continued low survi\'al in the summer of 1967. At that time, 48 per cent ( 10 of 21 ) of the animals taken were young. Apparently there were changes in the density of the long-tailed weasel (Mustela frenata) in the period of this study. Evidence for these changes consists of sight records, made during roughly 40 days spent in the field each summer, and on the number of weasels killed at the quadrats. (A total of approximately 2400 linear feet of electric fence was in operation each time a series of quadrats was studied. ) No weasels were taken at the quadrats in 1965, and only two weasels were seen. In 1966 six weasels were killed by the elec- tric fences and weasels were observed regularly; in 1967 four weasels were taken by the electric fences and many were seen. Although the data give only a general idea of abundance, weasels were clearly far more abundant in 1966 and 1967 than they were in 1965. Reproductive Cycles The reproductive cycles of only those species taken with regu- larity in the quadrats are discussed. Reproductive data are pre- sented in Tables 3-4 and in Figs. 4-8. 60 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 3. — Litter sizes, as indicated by numbers of fetuses and placental SCARS, IN SEVEN SPECIES. ThE MEAN NUMBER IS GIVEN, FOLLOWED BY THE standard ERROR, THE SIZE OF THE SAMPLE ( IN PARENTHESES), AND THE RANGE. Species Fetuses Placental scars Sorex vagrans 5.6 ±: .43 (7), 4-7 Eutamias minimus 5.7 ± .15 (52), 3-8 5.7 ± .15 (97), 2-10 Thomomy.s ialpoides 4.0 ± .53 ( 12), 2-7 5.0 ± .16 (66), 2-8 Peiomyscus maniculatus 5.6 ± .12 (111), 2-9 5.9 ± .31 (34), 2-10 Clethrionomijs gapped 6.1 ± .50 (10), 4-8 Phenacomijs intermedins 4.8 ± .75 (4), 3-6 5.3 ± .52 (11), 2-9 Microtus montanus 5.8 ± .25 (46), 2-10 Sorex cinereus Tliis species was uncommon in the quadrats, but was more abundant in nearby moist areas. Of the 19 indixiduals taken in the quadrats, four (21 per cent) were adults. Breeding apparently extends at least into September, for a pregnant yearling female with six fetuses was taken on September 3, and males with spermatozoa in their testes were taken on September 2. Young animals were recorded as early as July 14. Sorex vagrans Because of the small sample of this shrew (N=73) only a general picture of its reproductive cycle was gained. Clothier (1955) recorded pregnant S. vagrans from April 1 until August 8 in Montana. The seven pregnant shrews from the present study area were taken from June 15 to August 15. There was no evidence that breeding females (yearlings) had more than one litter in their second siuumer, and no young of either sex were recorded in breeding condition in their first summer. Fertile males (all yearlings) were taken from June through early September. Whereas but 11 per cent of the 31 females taken in August and September were yearlings, 56 per cent of the 18 males from this period were yearlings. Doubtless few females surxive their second sununer. The cessation of breeding in the late summer, therefore, may be due primarily to the loss of yearling females from the population. The mean number of fetuses for seven females was 5.6 (Table 3). Clothier determined a mean litter size of 6.4, based on 33 pregnant females from Montana. Eutamias minimus This species hibernates from October or November, depending on snow conditions, to the time of snowmelt in spring. In each year of the study, chip- munks were seen as soon as any snowfree ground appeared. Individuals were first noted in the study area as follows: June 13, 1965; May 15, 1966; June 7, 1967. Seemingly not all female chipmunks breed as yearlings. Of 93 females taken in June and July of 1966, for example, 17 (18 per cent) had threadlike uteri and gave no morphological indication of approaching estrous. These animals (hereinafter termed non-breeding females) averaged appreciably lighter in weight than did l^eeding females. Twenty-six breeding females in a sample from June, 1966, averaged 45.5 grams (range 37.2 to 58.7), whereas nine non-breeding females averaged 38.2 (33.6 to 42.1). Perhaps females that do not attain a certain critical weight in their first summer do not undergo Vaughan — Montane Small Mammal Fauna 61 100 80 60 40 5 20 < o a. estrous pregnant post-partum 20 40 60 80 lOOh o Z MONTHS Fig. 4. Summary of the reproductive cycle of Eutamias minimus based on samples of 177 males and 247 females. estrous in their second summer. If this he true, large numljers of non-breeding females would be expected in a year following a summer made unusually short by a late snowmelt and by early autumn snows. Reproduction in such a summer would be unusually low and the population density would be strongly affected. The female reproductive organs undergo development in preparation for breeding before the animals emerge from hibernation, because females are in estrous soon, within roughly a week, after emergence from hibernation. A sample of 18 females was taken at the height of snowmelt (May 18, 1966) at sites probably free of snow for one to two weeks. Four of these animals had embryos, nine had swollen, flaccid, highly vascular uteri and were judged to be in or near estrous, and five were non-breeding females. In some cases pregnant females were taken on soil saturated with water and adjacent to snowbanks up to fi\e feet deep. Much chasing of one animal by another occurred during snowmelt, an activity that I assumed to be associated with breeding. Virtually all except the non-l^reeding females were pregnant by mid-June. Of 31 reproductively active females taken at this time, one had placental scars and the rest were pregnant. For these females the mean size of the fetuses was 12 mm. (crown-rump length, full-term fetuses measured about 25 mm.). Parturition was largely completed by mid-July, for of 59 reproductive females taken in July only four had fetuses; the rest had placen- tal scars and enlarged mammae (see Fig. 4). The mean number of fetuses was 5.7; the mean number of placental scars also was 5.7 (Table 3). Litter size as indicated by this type of data did not differ appreciably from year to year. 62 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 100 90 80 70 h ^ 60 °50 O 40 I— 2 30 LU u OC m 20 O- 10 0 MONTHS Fig. 5. Percentages of young in the total monthly samples (representing 1965, 1966 and 1967) of four species. Sample sizes are as follows: Eutamias minimus, 424; Thomomys talpoides, 353; Peromi/scus maniculatus, 480; Microtiis mon- tanus, 195. Young chipmunks apparently stay in the nest roughly 30 days and begin appearing above ground in early August. From this time onward, they form a progressi\'ely larger proportion of the population. As shown in Figure 5, 54 per cent of the chipmunks taken in August ( N = 1 62 ) \\'ere young; for September the corresponding figure was 70 per cent (N=:61). There was no indication that any females enter estrous in their first summer. Records from 1966 illustrate best the reproductive cycle of the male. Snowmelt was at its height on May 18, when roughly half of the surface of the ground was still imder snow. Of a sample of 30 males taken on this date, 80 per cent were in lireeding condition. In these animals, die testes and the caudal epididymides contained spermatozoa and the seminal vesicles were enlarged and tiugid. The non-breeding males taken at this time were not individuals that had yet to reach breeding condition and would breed later, but rather were males that would not reach breeding condition during the summer. Each monthly sample contained such reproductively inactive yearling males. Prob- ably all males that would have bred in 1966 were in breeding condition at the time of snowmelt. The reproductive organs of males doubtless enlarge before the animals emerge from hibernation, for the testes and seminal vesicles averaged largest in recently-emerged males; both testes and seminal vesicles regressed rapidly in size from mid-July until August (Table 4). Spermatogene- sis was occurring in all of the reproductive males taken in May and mid-June, whereas of the 12 reproductixe males taken in July only four had spermatozoa in the testes. A continued reduction in spermatogenesis in August probably occurs, but I lack sufficient data to illustrate this trend. Vaughan — Montane Small Mammal Fauna 63 Thoniomys talpoides This species is active throughout the winter beneath the snowpack. In February, 1966, burrows were found extending at least one foot above the ground into the snowpack, which was roughly 50 inches deep. This species is a sharply seasonal breeder, and its reproductive cycle in my study area was similar to the cycles described for this species elsewhere in Colorado by Hansen (1960) and Vaughan (1967). In summer young of this species ( animals that have not been through a breeding season) can be distinguished easily from adults (animals that are in breeding condition or have been through a reproductive cycle). In addition to differences in total weights, adult females ha\'e pubic gaps whereas young do not (Hisaw, 1924; Miller, 1946; Hansen, 1960). Adult males in breeding condition have much larger bacula and testes than do young. In adult males with regressed testes, these organs are flaccid, reddish, and often partially wrinkled, whereas those of young males are tingid, yellowish or whitish, and have a smooth surface. Females had a single litter a year and bred early, in May or June. More than half ( 69 per cent ) of the June-taken females already had borne young, and only 10 per cent had not entered estrous (Fig. 6). In August only seven per cent of the adult females (N=31) were pregnant; the remainder had placental scars. No evidence was found of females breeding in their first MONTHS Fig. 6. Summary of the reproductive cycle of Thomomys talpoides based on samples of 191 males and 162 females. 64 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. Table 4. — Lengths of the testes and seminal vesicles in the summer MONTHS IN FOUR SPECIES. ThE MEAN LENGTH IS GIVEN, FOLLOWED BY THE standard error and THE SIZE OF THE SAMPLE ( IN PARENTHESES). Species Month Testes Seminal vesicles Eutamias minimus May 10.1 ±.38 (30) 6.81 ± .32(30) June 8.9 ±.26 (64) 6.2 ± .19(61) July 6.5 ±.26 (49) 4.2 ± .24(47) August 5.2 ± .20 (28) 3.6 ± .22 (28) September 6.3 ± .38 (6) Thomomtjs talpoides May 19.0 ± .53 (4) 14.8 ± .07(4) June 16.8 ± .33 (33) 13.8 ± .75(33) July 14.5 ± .45 (21) 10.8 ± .70(21) August 11.3 ±.42 (31) 8.8 ± ..57(31) September 9.7 ± .95 (2) Pcromiiscus maniculahis May 8.4 ± .19 (8) 8.4 ± .28(8) June 8.7 ±.10 (98) 9.9 ± .17(99) July 9.2 ± .18 (36) 10.8 ± .36 (36) August 8.9 ±.39 (16) 10.0 ± .52(16) September 5.1 ± .11 (4) Microtus montaniis June 10.8 ± .17 (7) 13.4 ± .43(7) July 11.0 ±.46 (3) 10.5 ±1.4 (3) August 9.9 ± .40 (27) 12.6 ± .60 (27) September 11.8 ± .67 (2) 12.4 ± .14(2) summer or of females bearing two litters per year. The mean number of fetuses and placental scars per female was 5.0 and 4.0, respectively (Table 3). The reproductive organs of males undergo marked seasonal changes in size and probably reach maximum dexelopment at about the time of snowmelt (late May or early June), after which the testes and seminal vesicles of adults become progressively smaller through the rest of the summer (Table 4). In August only 30 per cent of the adult males examined (N=30) were fertile. Young males do not become fertile in their first summer. Young pocket gophers were first recorded in June, and formed an ever increasing part of tlie population during the rest of the summer (Figs. 5-6). Seventy six per cent of the pocket gophers taken in September (N=58) were young. Peromyscus maniculatus Litde information bearing on the winter activity of this species is available from the study area. Several specimens have been taken in the winter in partially snow-free areas, and during snowmelt in the spring some of the runways and nests beneath log piles and matted vegetation were probably those used by Peromyscus in the winter. Such evidence suggests that in the study area this species remained active at least part of the winter beneath the deep snowpack. Tracks, judged to be those of Peromyscus, were occasionally seen on the surface of the snow in midwinter, but this animal probably was active mostly in the depth hoar beneath the snowpack. Females breed soon after snowmelt. About 33 per cent of the females in a small sample taken during snowmelt in May of 1966 were pregnant (Fig. 7). Because no young animals were encountered at this time it seems unlikely that breeding began before snowmelt. The percentage of pregnant females in monthly samples declined from a high of 89 per cent in June to 38 per cent in Vaughan — Montane Small Mammal Fauna 65 100 80 60 LU40 Q- <20 ° 0 z LU u20 UJ Q. 40 60 80 100 FEMALES MALES Y/4f, post - par tum pregnant J) o •E 0) o > -o ■ 0 J^^^^^j B W/ 1^ _aj , 0 E Li- > -D 0 i 0) a 01 c o Z c o Z , . M J J A S N M J J MONTHS Fig. 7. Summary of the reproductive cycle of Peromtjscus maniculatus l:)ased on samples of 260 males and 220 females. August (Fig. 7), and no pregnant females were taken after August. Some yearling females that bred in May or early June had a second litter before September as females that had olniously suckled young and were carrying fetuses were noted regidarly. In addition, some, but seemingly not all, young females bred during their first summer; a few small, partially gray-pelaged females with fetuses were taken in August of 1965 and 1966. The late summer decline in the percentage of pregnant females in the population seems due to a cessation of breeding by yearling or older females (and to their death) and to a low percentage of young females that breed in their first summer. The reproductive burden for the population, then, seems to be borne primarily by the overwintering yearling females. Litter sizes were large in the study area. The mean number of fetuses and placental scars was 5.6 and 5.9, respecti\'ely (Table 3). These averages did not differ significantly from year to year. Large litters were judged by Spencer and Steinhoff ( 1968 ) to be typical of popidations of P. maniculatus occupying areas with short growing seasons, where the animals must make the most of a short period of food abundance. Mean litter size in the present study was considerably larger than the 4.6 determined by Jameson (1953) for P. maniculatus occurring at elevations between 3500 and 5000 feet on the western slope of the Sierra Nevada Mountains in California, where the breeding season in one year of his study extended from April through No\'ember. Considering both sexes, the age structure of the population of P. manicu- latus in the present study area imderwent striking and similar changes each summer of the study. June samples contained almost entirely yearling ( or older) breeding animals. Reflecting the sudden onset of breeding in early 66 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. summer, young appeared suddenly and in large numbers in July, when they averaged 40.5 per cent of the female population and 61.0 per cent of the male population. Young animals formed a progressively higher percentage of the population through the rest of the summer and autumn (Figs. 5 and 7). A small sample (N=21) from November consisted entirely of young of the year, indicating that individuals of either sex rarely sur\'i\ed a second autumn. The breeding population of May and June, therefore, probably consisted entirely of animals born the previous summer. All adult males taken in May and nearly all (97 per cent) taken in June were fertile, but the percentage of fertile males in the population became progressively lower from July (65 per cent) a: d August (61 per cent) to September, when none was taken. The testes and seminal vesicles of yearling males do not regress appreciably in size through the summer (Table 4). Such males probably remain continuously in breeding condition through the summer, but by September the reproductive organs of the few surviving yearlings are regressed and the animals are not fertile. Young males born early in the summer begin producing sperm when the animals weight but 15 grams, less than 75 per cent of the weight of fully grown males, whereas young that are born later in the summer do not become fertile until the following summer. None of the yoimg individuals taken in September and November, even those weighing more than 15 grams, was fertile. Clethrionomys gapperi This was one of the least common rodents on the study area. Breeding extended at least from May through November, because juvenile mice were taken at irregular intervals from May through late December. Ten pregnant individuals were captured in July and August, and the mean number of fetuses was 6.1 (Table 3). Adult females have more than one litter per summer, and young animals breed in their first summer. Several small August- taken females with nearly unworn teeth carried fetuses or had placental scars and were judged to have been born earlier in the summer. In several small males of roughly the same age as these females, spermatozoa were abundant in the testes and the caudal epididymides. Phenacomys intermedius This rodent was never common in the (luadrats and most individuals were taken in late summer or in autumn. The occurrence of fertile males from the time of snowmelt in May in one year (1966) until late August, and the occurrence of pregnant females from June through September, indicates that breeding takes place through most of the sununer. Females are polyestrous in Colorado according to Warren (1942). An August-taken female weighing only 16 grams (roughly half the weight of a fully grown female), and having nearly unworn teeth, was pregnant, and males of similar size from mid- summer had sperm in their caudal epididymides. This evidence indicates that young animals born early in the summer breed in their first summer. Young animals born later in the year seemingly do not reach breeding condition their first autunm, however, for none of four November-taken males, weighing from 17 to 23 grams, was fertile, and three young females (18 to 29 grams) taken at the same time had transparent, threadlike uteri. The mean number of embryos and placental scars was 4.8 and 5.3, respectively (Table 3). Vaughan — Montane Small Mammal Fauna 67 Miciotus montanus Tliis species is not known to hilx'inate. In the stndy area abundant evi- dence, in the form of runways and nests made in winter and uncoxered dining snowmelt, indicated that montane \'o!es were active through the winter beneath the snow. Because no specimens were taken in the winter, and because few were caught until July, it is not known if l:)reeding occurred in the winter. Compared to other rodents of the area, these \oles have an unusually long breeding period. The females taken earliest in the year were caught during snowmelt on May 17, 1966; these two individuals had placental scars, had recently suckled young, and were taken at a site that had been free of snow for but a few days. These animals iniqnestionably had their litters beneath the snowpack. Breeding continued from snowmelt at least through August, when 54 per cent of the females taken carried embryos (Fig. 8). Hall (1946) found that in Nevada this species breeds through November, and this may well be true for the present study area. Young of the year were distinguished from yearlings primarily on the basis of weight ( indi\'iduals of more than 3.5 grams were classed as yearlings), and it seemed that most of the pregnant individuals 100 80 60 ^40 CL <20 Z 0 20 > 3 o Q. Z^o u a. 3 u o 60 ' Q. 4J c 80 . O Z 100 c o z -I J A J J A 5 MONTHS Fig. 8. Summary of the reproductive cycle of Micwtus iiiouiaiuis based on samples of 111 males and 84 females. 68 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. taken in August were animals born earlier in the summer. Small females weighing but 17 grams had embryos, and some indi\iduals weighing less than 20 grams had placental scars. Of 33 pregnant females taken in August, only five (15 per cent) were judged to be yearlings. Seemingly, tlien, as yearling females that bred early in the siunmer are increasingly outnumbered by young females, a progressively greater share of the reproductive burden shifts to young females. The shaip rise observed in August in two years in the popula- tion density of M. montanus indicates that the young breeding females that form a major part of the relatively high August population probably contribute considerably more yovmg to the population than do the few yearling females that survive die winter and participate in early summer breeding. It would be expected, therefore, that the size of the population in the autimin would be determined primarily by the survival rates of early summer litters. The mean number of fetuses for 46 pregnant females was 5.8, and did not differ significantly between summers. This is similar to the litter size recorded by Hall (1946) in Nevada. Most of the males trapped each summer from June through August were fertile (Fig. 8). Males began producing sperm whe i they were roughly 20 to 25 grams in weight, and only three of the 37 males (eight per cent) that weighed more than 25 grams were not fertile. In the mondis from which specimens are available, no important changes in the mean sizes of the seminal vesicles and testes of males heavier than 25 grams were noted (Table 4), indicating that males stay in breeding condition through the summer. Young males far outnumber yearling males in July and August, and probably most of the breeding from mid July or August until winter is done by young males. Young males first appeared in the population in June and formed an increasing segment of the population through the remainder of the summer (Fig. 5). Of 75 males taken in August, 65 (88 per cent) were judged to be young. Discussion The yearly cycle of breeding and of changes in the densities of the small mammals of the study area has been influenced by several demanding environmental features: (1) a short annual growing season, averaging about thee months, and a snow-free period of about five months; (2) low temperatures tlirough most of the year and a frost-free period of only about 60 days; (3) annual "catas- trophes," first in the form of snowmelt, attended typically by flood- ing of much of the surface of the ground, and second, in the form of periodic "open" autumns, \\'hen temperatures approach zero but no snow cover that protects small mammals from the cold has developed. Some characteristic aspects of the life cycles of sub- alpine small mammals probably haxe developed in response to restrictions imposed by these environmental features. The reproducti\ e cycles of the small mammals considered here seem adapted to the short growing season. Adaptations include large litters and few litters per year. In addition, reproductive Vaughan — Montane Small Mammal Fauna 69 organs enlarge and mature while snow still covers the ground, and breeding occurs during or immediately after snowmelt. Of the five most common species, three — T. talpoides, E. minituus and S. vagram — ha\'e but one litter per year. Another, P. maniculaius, is polyestrous, but breeding is confined to the summer months and ceases in September. Only M. niontanus has a long breeding period; this season coincides roughly with the snow-free part of the year. Even this species, however, has large litters relative to those of other voles in less boreal areas. Corthum (1967) found that in Indiana M. ochrogaster and M. pennsylvanicus had litter sizes of 3.9 and 4.5, respectively, and that breeding occurred throughout the year. In the present study area, by contrast, M. monfanus had a litter size of 5.8 and roughly a fixe-month breeding period, giving this species a substantially lower reproductive potential than that of either species studied by Corthum. The presence of a faii'ly high per- centage of non-reproductive yearling E. minimus in the population is noteworthy. Perhaps the time from birth to first hibernation is so short at high elevations that some individuals born unusually late do not reach a critical stage of development ( size? ) before hiberna- tion and therefore do not become sexually active in the usual breeding season during and immediately after snowmelt. All of the small mammals in the present study area, despite large litter sizes, ha\'e fairly low reproductive potentials because few litters are produced annually. It may be, however, that the partial protection against predation afforded by a continuous, deep snow cover for seven months of the year compensates for a low reproductiv^e rate. The timing, length and severity of snowmelt probably has a strong influence on small mammal populations. Most of these mam- mals are forced to abandon low-lying or poorly-drained sites during the height of snowmelt, and local, temporary shifts to drier sites occur (see Ingles, 1949; Hansen, 1962). Local concentrations of chipmunks were observed during the snowmelt periods of 1965 and 1966. From June 14 to 18 of 1965, for example, continuous deep snow covered roughly 75 per cent of the surface of the ground. Strips of bare but saturated soil occured along the southern borders of stands of conifers and on certain south- or west-facing slopes. Chipmunks had emerged from hibernation in these areas and were concentrated around logs, stumps, and rock piles, sites where the animals could mostly avoid the saturated soil and running water. Although these shifts occur when population densities are lowest, 'f the occupancy of these refuges is maintained locally into the time 70 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. of natality by a prolonged snowmelt or by an unusually heavy run- off, the resultant crowding and heightening of interspecific competi- tion would be expected to decrease markedly the sur\ ival of young. In the early summer of 1965 dead montane voles and pocket gophers were found occasionally at low-lying sites; Hansen (1962) also found dead pocket gophers during snowmelt in southern Colo- rado. This limited exidence, supported by our lack of success in trapping small mammals in areas saturated with water from snow- melt, suggests that animals that are not able to move to dry refuges during snowmelt are drowned or die of exposure. Jenkins (1948) thought that periodic flooding of meadows in the Sierra Nevadas of California affected population levels of M. montanus. One of the difficulties small mammals face at such times \\'as made apparent when a tent that I pitched on frozen ground in the morning on May 15, 1966, was awash with flowing water when I returned in late afternoon of the same day. At this time of the year J.apus princeps and Sorex pohistris were taken occasionally on open slopes where they were never recorded later in the summer. Another transition period, that from summer to winter, may be a time of stress for small mammals. As pointed out by Formozov (1946) andPruitt (1957, 1960) certain small mammals (for example, shrews and \ oles ) retreat beneath the snow when it reaches a depth of six inches or more. These animals spend the winter in a moist subnivean en\ ironment where the temperature remains fairly con- stant at close to freezing and where they are insulated by snow from the violent climatic fluctuations frequently occurring above them. If a snowpack does not develop before extreme cold descends, how- ever, small mammals (such as M. montanus) that seek plant material for food on the surface of the ground are forced to forage for frozen, low quality food without protection from extreme cold that imposes considerable metabolic demands. Appreciable mortality may occur at such times. Such snowless conditions persisted into early No\'em- ber of 1965, and at this time no M. montanus were taken on the surface of the ground despite intensixe trapping. At this time the soil was frozen to a depth of several inches, and temperatures of -4°F were recorded on two nights. The unusually low populations of M. montanus in the summer of 1966 may have been due, in part, to this late de\ elopment of a snow cover in the autiunn of 1965. When snow does not co\'er the ground, voles may avoid difficult conditions on the surface by confining much of their activity to beneath the ground. In early summer of 1966 the few M. montanus Vaughan — Montane Small Mammal Fauna 71 taken were trapped in abandoned burrows of pocket gophers; no voles were taken at this time on the surface of the ground. Finally, what are the most important factors controlling fluctua- tions of population densities of small mammals in the study area? Natality seems fairly constant for each species from year to year. A consideration of sources of mortality, consequently, seems most germane. Under some conditions abundance or quality (or both) of food are thought to influence mortality ( Keith et al., 1959; Schultz, 1964). Food is seemingly not a limiting factor in the study area, however, for I considered the vegetation and the food habits of the mammals ( unpublished data ) and found ample food to be available each year. In my judgment, the most important factors controlling populations are the length, timing, and severity of snowmelt in the spring, the time at which a continuous snowpack first develops in the autumn, and the intensity of predation. Only predation needs further comment. The most abundant and seemingly most important mammalian predator of small mammals in the study area seemed to be the long- tailed weasel. Elsewhere in Colorado I have observed weasels chasing chipmunks and have found Microtiis in weasel stomachs, and weasels have frequently been taken in pocket gopher burrows in Colorado (Vaughan, 1961). It seems reasonable, therefore, that weasels in the study area were pre\'ing mostly on terrestrial rodents. As mentioned earlier, weasel density fluctuated in the period of this study, but was high during the summer of 1967, a time when density of small mammals was low. As pointed out by Pearson ( 1966 ) , the most important predator-prey interactions, in terms of eff^ects on rodent populations, are those that occur when rodent density is low. It may be that in montane situations the patterns of rodent cycles are modified by periodically intense predation when weasels are abundant and populations of preferred prey, such as pocket gophers, are low. Summary A series of electric fences, each fence enclosing a half-acre quad- rat, was used to study population densities of small mammals in a subalpine area in northern Colorado, and information on reproduc- ti\e cycles, based on dissections of 1639 animals, was obtained for the eight most common species. The climate of the study area is sharply seasonal, with snow on the ground for about seven months of the year. Reproduction and population cycles of small mammals seem dominated by this de- 72 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. manding climatic pattern; in most species the period of natality is short relatixe to the long period of mortality and population decline. Following are some basic features of the life cycles of the small mammals of the study area: 1. Population densities fluctuated widely, but an annual cycle involving low populations immediately after snowmelt in early sum- mer and high populations in late summer seemed characteristic. 2. Yearly and month-to-month changes in the relative and abso- lute densities of the different species in the summer were the rule. Population densities of Microtus montanus seemed most variable. 3. Because nearly 100 per cent mortality occurred each summer among yearling animals of three species (Peromyscus manictdohis, Sorex vagrans, and M. montanus), and young of the year comprised most of the autumn populations of the other two of the five most common species (Thomomijs tolpoides and Eutamios minimus), survival rates of young animals was a primary factor influencing population levels. 4. Large litters are characteristic of all species, and most species have short seasons of natality. Of the five most common species, three (T. tolpoides, E. minimus, and S. vagrans) have one litter a year and two (P. maniculatus and M. montanus) are polyestrous. In E. tninimus a substantial segment of the yearling population each year does not breed, a unique situation perhaps associated with short growing seasons. 5. The striking fluctuations in the densities of small mammals seem most strongly influenced by the duration, severity, and timing of snowmelt, by the time at which the ground is first continuously covered by snow in the autumn, and by predation, particularly when, as occurred in 1967, high populations of weasels and low popula- tions of rodents occur concurrently. Literature Cited Bailey, V. 1932. Mammals of New Mexico. N. Amer. Fauna, 53:1-412, 22 pis., 58 figs. Browx, L. N. 1967. Ecological distribution of six species of shrews and comparison of sampling mediods in die central Rocky Mountains. Tour. Manim., 48:617-623, 1 fig. Clothier, R. R. 1955. Contribution to the life historv of Sorex vagrans in Montana. Jour. Mamm., 36:214-221. CoRTHUM, K. W., Jr. 1967. Reproduction and duration of placental scars in the prairie ^•ole and the eastern vole. Jour. Mamm., 48:287-292. Vaughan — Montane Small Mammal Fauna 73 FoRMOZov, A. N. 1946. The covering of snow as an integral factor of the environment and its importance in the ecology of mammals and liirds. Material for Fauna and Flora of USSR, New Series Zoology, 5:1-141, 26 figs. (Russian with 11 unnumbered siunmary pages in French). GrIXXELL, J., J. DiXOX, AXD T. M. LiXSDALE 1930. Vertebrate natural history of a section of northern California through the Lassen Peak region. Univ. California Publ. Zool., 35:v + 1-594, 181 figs. Grinnell, J., AND T. I. Storer 1924. Animal life in the Yosemite. . . . Univ. California Press, Berkeley, xviii + 752 pp., 60 pis., 65 figs. Hall, E. R. 1946. Mammals of Nevada. Univ. California Press, Berkeley, xi + 710 pp., frontispiece, 11 pis., 485 figs. Haxsex, R. M. 1960. Age and reproductive characteristics of mountain pocket gophers in Colorado. Jour. Mamm., 41:323-335, August 15. 1962. Movements and survi\al of Thomomtjs talpoides in a mima-mound habitat. Ecology, 43:151-154, 3 figs. Hisaw, F. L. 1924. The absorption of the puliic symphysis of the pocket gopher, Geomys bursarius (Shaw). Amer. Nat., 58:93-96. IXGLES, L. G. 1949. Ground water and snow as factors affecting the seasonal distribution of pocket gophers, Thomomijs monticola. Jour. Mamm., 30:343-350, 2 pis., 1 fig. Jameson, E. W. 1953. Reproduction of deer mice (Peromiisctts maniculatus and P. hoylei) in the Sierra Nevada, California. Jour. Mamm., 34:44-58, 4 figs. Jexkins, H. O. 1948. A population study of the meadow mice (Microiiis) in three Sierra Nevada meadows. Proc. California Acad. Sci., ser. 4, 26:43-67, 11 figs. Keith, 1. O., R. M. Hansen, and A. L. Ward 1959. Effect of 2,4-D on abundance and foods of pocket gophers. Jour. Wildlife Mgt., 23:137-145, 2 figs. Miller, M. A. 1946. Reproductive rates and cycles in the pocket gopher. Jour. Mamm., 27:335-358, 6 figs. Pearson, O. P. 1966. The prey of carni\'ores during one cycle of mouse abundance. Jour. Anim. Ecol., 35:217-233, 9 figs. Pequegnat, W. E., and D. H. Thompson 1949. An electric fence for studving rodent populations. Jour. Entomol. Zool., 41 (3): 1-37, 6 pis., 9 figs. Pruitt, W. O., Jr. 1957. Obserx ations on the microclimates of some taiga mammals. Arctic, 10:131-138. 1960. Animals in the snow. Scientific Amer., 203(6) :61-68. SCHULTZ, A. M. 1964. The nutrient-recovery hypothesis for arctic microtine cycles. II. Eco- systemic variables in relation to arctic microtine cycles. Pp. 57-68 in Grazing in terrestrial and marine environments ( D. J. Crisp, ed.). British Ecol. Soc, Symp. no. 4, Blackwell, Oxford, England. Spexcer, a. W., and H. W. Steixhoff 1968. An explanation of geographic variation in litter size. Jour. Mamm., 49:281-286, 1 fig. 74 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Vaughan, T. a. 1961. Vertebrates inhabiting pocket gopher burrows in Colorado. Jour. Mamni., 42:171-174. 1967. Two parapatric species of pocket gophers. Evolution, 21:148-158, 5 figs. Warrex, E. R. 1942. The mammals of Colorado, their habits and distrilxition. Uniw Oklahoma Press, Norman, xviii + 330 pp., frontispiece, 50 pis. THE SPECIES PROBLEM IN THE THOMOiMYS BOTTAE— THOMOMYS UMBRINUS COMPLEX OF POCKET GOPHERS IN ARIZONA BY Donald F. Hoffmeister In southwestern United States and northern Mexico, there are two common, small pocket gophers, Thomomijs hottae and Tho- momijs umbrinus. These are allopatric nearly everywhere (Fig. 1). Where the two occur together or adjacent, there has always been considerable doubt as to which "species" any population should be referred. This has been true in southwestern Texas ( Davis Moun- tains), southern Arizona, eastern Coahuila, and eastern Sinaloa. The two "species" have been regarded as conspccific on some occa- sions and as distinct species on other occasions. In 1959, Hall and Kelson regarded the tw^o as conspecific basing this on the remarks of Hoffmeister and Goodpaster (1954:95). Gophers in the Huachuca Mountains, Arizona Hoffmeister and Goodpaster, working in southern Arizona (1954), regarded Thomomijs hottae and T. umbrinus as conspecific for a variety of reasons. Mearns (1897:719) described a pocket gopher "from the aspen and spruce zone at the summit of the Huachuca Mountains" that had the characters of Thomomys um- brinus. Our collecting on the summit of these mountains in a clear- ing in the aspens and fir revealed an isolated population of gophers that had the features of T. bottae, and since two characters sup- posedly valuable in distinguishing bottae and umbrinus were vari- able— namely color and number of pectoral mammae — we con- cluded that in the Huachuca Mountains, Arizona, it is "advisable to refer all material to one species, for which the earliest name is T. bottae [but] by this we do not mean to imply that T. umbrinus is necessarily a synonym of T. J)ottae" (Hoffmeister and Goodpaster, 1954:95). Further collecting in the Huachuca Mountains indicated that at intermediate elevations, between the summit and the bahada, a distinct kind of gopher exists and these are referable to Thomomys un\hrinus. Re-examination of the 87 gophers that Hoffmeister and Goodpaster studied in the Huachucas indicates that seven are refer- able to T. umbrinus, and these seven are from the oak-belt on the (75) 76 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. I BOTTAE i ; Fig. 1. Distribution of Thomomys hotiac and Thomomijs umhiimis in western North America. Specimens from parts of the range marked with a question mark have been regarded as more bottacAike than umbrmus-]ike by some authors. Mountains. The type of Mearns' gopher indeed is umbriniis-\ike. We doubt that it came from the summit of the higher peaks of the Huachucas. In any event, it is clear that in the Huachuca Moun- tains, Arizona, there are two kinds of pocket gophers — T. bottae and T. unihrinus. HOFFMEISTER ThOMOMYS IN ARIZONA / / Fig. 2. Range of Thomomys bottae and Thomomijs iimbrimis in Arizona. Sycamore Canyon, Patagonia Mountains, the area of study, is immediately above the tip of the arron'. Gophers in the Patagonia Mountains, Arizona In Arizona, Thomoimjs hottae and Thomomys umhrinus are allo- patric in three counties, Cochise, Santa Cruz, and Pima (Fig. 2), and are to be found within a half-mile or less of each other at more than 10 localities. One of the most interesting of these is Sycamore 78 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Canyon on the west side of the Patagonia Mountains, Santa Cruz County. In the higher parts of the Patagonias, timbrinus-]ike go- phers are found; in the Santa Cruz River Valley, to the west of these mountains, the gophers are l)ottae-\i\:e. T. bottae is found up the Canyon as far as 4400 feet elevation; T. umhriniis down the canyon to 4100 feet elevation (Fig. 3). In some places along this canyon, the two kinds of gophers are to be found "together" and in other places seem to be intermediate, as if intergrading or hybridizing. In southern Arizona where the two kinds occur so close together, there is no character displacement and it is difficult to select charac- ters useful in differentiating the two kinds. Previous Methods for Distinguishing the Two Kinds Bailey (1915), in his revision of the pocket gophers of the genus Thomomijs, recognized a Thomomys umhrimis group but did not formally characterize it. However, features of one pair of pectoral mammae, dichromatic color, and short skull were mentioned. Nelson and Goldman (1934) more clearly defined T. umbriniis, pointing out that the species is "normally recognizable by the diflering num- Ifl f 1 f 9 3 4 5b' °- « ;■- ] 2 . . .-.. ■♦■: .•.♦.1^ ' ''''■'■' > • , «. , ■.■■:-: 5700 5300 4300 4500 4100 3700 Fic;. 3. Collecting sites in Sycamore Canyon. Elevation in feet is indicated in the upper transect. The dotted line indicates the road up the Canyon. The scale is for one mile. The Santa Cruz River Valley is to the left, \\'est of Arizona Highway 89. The crest of the Patagonia Mountains it to the light. HOFFMEISTER ThOMOMYS IN ARIZONA 79 bcr of pectoral mammae (one pair in umhrinus, two pairs in hottae) and in the summation of cranial details, none of which is very trenchant" (p. 105). Blair (1939) characterized T. umhrinus by "small, rounded skull, small size, and weak forefeet." Davis (1946: 266) in characterizing T. umhrinus employed the variation in "the margin of the anterior base of the zygoma where it meets the frontal." This character is shown in Figs. 8-9. Goldman (1947:6) characterized the TJwmomys umhrinus group by certain color and cranial features, but not by the number of pectoral mammae. Baker (1953), in studying the pocket gophers in Coahuila, used the char- acter of the maxillo-frontal suture, the position of the lacrimal, and the procumbency of the incisors in separating umhrinus and hottae. Anderson (1966:196) noted that 17 characters are seemingly useful in distinguishing the two species in Chihuahua, but specifically mentioned only seven of the 17 characters, and these only in a casual way. Dunnigan (1967:142-144) pointed out several characteristics useful in separating Sinaloan specimens of the two species. in — 11-1 o 1 f 9 3 4 5-6-J i^ . 2 . - -♦.■ ,» .»,1^'-V ■■•-•• :' t ' , , ■,■■■■ ■.■,■-■.•, - ■:-; 5700 5300 4900 4500 4100 3700 bottae intermediote umbrlnus 37 0 0 dorsal coloration 6 7 2 0 0 10 2 1 1 0 9 6 7 5 1 i 24 Fig. 4. Distribution of gophers with hottae color (1 and 2 of Fig. 6), inter- mediate, or r(/)i/jn'jiH.s-color (5 and 6 of Fig. 6). The 37 gophers from below Sycamore Canyon (lower left corner) all are hottae-]ike in color; two of the wnbiimis (lower right corner) are intermediate in color. On the map at locality 6, for example, two specimens were like bottae in color, two were intermediate, and six resembled umhrinus. 80 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. The characters employed by these various workers are not useful individually in separating the two kinds in Arizona nor is a com- bination of their characters highly reliable either. Coloration, in- cluding the presence or absence of a broad, dark dorsal stripe, is variable, although often useful. Most specimens regarded as T. umhrinus have one pair of pectoral mammae and most T. hottae have two pair, although there is variation in this character as well. Among approximately 200 specimens of T. hottae from Arizona, on which field examination for number of mammae was made, five have only one pair, not two. Nelson and Goldman (1934:117) I recorded at least one, possibly three, other T. hottae with a single pair of pectoral mammae. Variation in the shape of the maxillo- j frontal suture and in the position of the lacrimal at one locality in Arizona is summarized in Figs. 8-9. Some of the variation in cranial and external measurements in the population in Sycamore Canyon, Arizona, is shown in Table 1. The variation from throughout the range of T. hottae or T. umhrinus would show the overlap in l measurements to be even greater. ' ' all those color-coded 4, 5, and 6, have a somewhat purplish cast o\'erlying the ochraceous on the sides. Cranial measurements were taken as indicated in Figure 7. Only animals judged to be adult were used. Specimens were placed in four age-groups. In the oldest group, the basioccipital-basisphenoid suture is closed, the supra- occipital-exoccipital suture closed, and the temporal ridges prominent in both sexes, but less so in females. In the next younger group, the ]>asioccipital- basisphenoid suture is not closed (X in Fig. 7), the supraoccipital-exoccipital suture mostly closed (Y in Fig. 7), and the temporal ridges present but only moderately prominent. The two younger groups were not used. Males and females were treated separately because of the secondary sexual variation (Table 1). The position where the maxillo-frontal suture comes in contact with the lacrimal varies (Fig. 8), and this variation is given a value of 1 for hottaeAike, 2 for intermediate, and 3 or 3.5 for umbrinusAike. The shape of the maxillo- frontal suture, from concave (Fig. 9) to convex, is given a similar value of 1, 2, and 3 or 3.5 from /;o^f«c'-like to umbrinusAike. Characters Useful in Distinguishing Gophers IN Southern Arizona In separating bottacAike and ti>nJ)iinus-]ike gophers in southern Arizona, the following color and morphological features were most useful. They are probably of decreasing value in the order given except for the analysis of chromosomes. Dorsal coloration. — T. umbrimis has a dark band running from the tip of the nose to the base of the tail. The width of the band varies. Usually it is broadest in the middle of the back and also extends completely between the eyes and ears. Immediately below the black band, the lateral coloration is ochraceous, usually with an o\erlay of color, hard to describe, that gives an iridescent or purplish cast. T. bottae has the lateral coloration extending over the back, with a slight sprinkling of dark hairs in the middorsal area. Rarely is there an indication of a dark band (see Fig. 6). Number of pectoral mammae. — T. umhrinus has only one pair of pectoral mammae; T. bottae two pairs. Variation from this arrangement is discussed above. Length of bactilum. — In eastern Santa Cruz County, the greatest length of the baculum in T. bottae is usually more than 11.0 mm.; in T. umbrinus, usually less than 10.2 mm. External measurements. — For eastern Santa Cruz County, body length in adult male T. bottae is usually more than 152 mm.; in T. umbrinus, less than 149; in females, there is overlap, with T. bottae more than 138. T. umbrinus less than 143. The hind foot is usually longer than 29.5 mm. in male T. bottae, less than 29.2 in male T. umbrinus; more than 27.0, rather than less, in female T. bottae. There is overlap in length of tail, but in male T. bottae it is usually more than 60 mm., in T. umbrinus, less. Cranial measurements. — The most useful cranial measurements were basilar length, zygomatic breadth, mastoid breadth, and length of nasals. There is less overlap in these measurements between males of the two species than in 84 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 1. — Measurements (ix millimeters), valltes (position and shape of MAXILLO-FROXTAL SUTURe), AND NUMBERS (mAMMAe) FOR VARIOUS FEATURES OF MALE AND FEMALE Thomomys bottac AND T. umbrinus from the Santa Cruz River Valley near Nogales and the Patagonia Mountains, respec- tively. The mean is followed by plus or minus one standard devlatioxN. Measurement Males Females bottae umbrinus bottae umhrimis (xN=ll) (N=9) (N=26) (N = 17) Length of body ..163.6 ±5.57 137.8 ±5.59 152.7 ±7.30 130.5 ±12.52 Length of tail . 70.1 ±5.17 55.1 ±3.41 63.8 ±4.08 52.1 ± 4.78 Length of hind foot _ 31.0 ±0.77 27.1 ±1.05 29.7 ±1.38 25.2 ± 0.97 Basilar length - 35.S6±0.68 31.04±0.91 32. 89 ±1.06 29.40± 1.11 Length of nasals .. 14.39±0.63 12.69±0.45 12.76±0.65 11.45± 0.62 Zygomatic breadth - 25.87±1.00 22.31 ±0.81 23.50±0.66 21.02± 0.84 Mastoid breadth - - 21.31±0.51 18.38±0.52 19.87±0.64 17.36± 0.55 Interorbital breadth . 6.76±0.08 6.73±0.29 6.85±0.26 6.69± 0.18 Length max. toothrow _ 8.22±0.30 7.63±0.41 8.30±0.43 7.62 ± 0.25 Length of rostrum . 17.52±0.42 15.07±0.39 15.72±0.63 14.04± 0.71 Breadth of rostrum . 8.68±0.35 7.91±0.32 7.95±0.29 7.34± 0.26 Suture position ( 1-3.5 ) . 1.18±0.40 2.33±0.50 1.58±0.50 2.71± 0.47 Suture shape (1-3.5) . 1.18±0.40 2.22±0.45 1.23±0.38 2.71 ± 0.56 Dorsal color (1-6) . 1.27±0.47 4.67±1.87 2.04±0.82 5.41 ± 0.79 Length of baculum . 11.97±0.51 9.19±0.52 Height of baculum ( base Pairs pectoral ) 2.08±0.25 1.90±0.19 mammae 2 1 females. In males in eastern Santa Cruz County, basilar length is usually more than 34.4 mm. in T. bottae, less than 32.9 in T. umbrinus; zygomatic breadth more than 23.9 mm. rather than less than 23.9; mastoid breadth more than 20.2 mm. rather than less than 19.4; nasals usually longer than 13.4 mm. rather than shorter. In females the overlap is indicated by the fact that basilar lengtli is usually more than 30.8 mm. in T. bottae, less than 31.6 in T. umbrinus; zygomatic breadth is more than 22.2 mm. in T. bottae, less than 22.7 in T. urnbrinits; mastoid breadth is more than 18.5 mm. in T. bottae rather than less; nasals are longer than 11.5 mm. in T. bottae, shorter than 12.6 in T. umbrinus. Position and shape of the maxillo-frontal suture. — The position and shape of the maxillo-frontal suture are discussed above and in Figures 8-9. The position- \alues given in these figures indicate the variability of each character. Further- HOFFMEISTER ThOMOMYS IN ARIZONA 85 umbrinus bottae 1 2 3 4 5 6 7 8 9 10 11 42 49 5 1 8 7 ;6 9 9 6 2 2 2 4 1 5 1 2 1 J 0 0 0 0 ; n f e r m e d I a f e 5 16 0 0 2 2 1 2 2 0 0 1 0 1 0 7 2 12 5 6 3 2 1 1 0 0 0 2 I I 0 3 0 0 7 Fig. 8. Position of the maxillo-frontal sutiire relative to the lacrimal (see arrow). In hottacAike gophers, the suture reaches the lacrimal near the center of that bone, but in (//»/;)/;H/.s-like gophers the suture reaches the lacrimal near the medial side. The 42 specimens of tnnhriniis, 49 of hotfae, and those from each of the 11 localities in Sycamore Canyon (left colimin) are scored as to whether they are bottae-Mke, ttmbrinttsAike, or intermediate. more, it is frequently difficult to ascertain if the maxillo-frontal suture is straight or convex, or its precise position relati\ e to the lacrimal. Length and breadth of rostrum. — In males of T. bottae, the length and breadth of the rostrum, respectively, is usually more than 16.3 mm. and 8.3 mm. rather than less; in females, usually more than 14.9 and 7.6 rather than less. CJiromosomes. — Analysis of the chromosome numl^er and karyotypes in the Patagonia Mountains has been made by Patton and Dingman (1968), and the following summary is from their report. "Typical" specimens of T. bottae have 2n=:76, no acrocentrics or minute chromosomes, with all being metacentrics, submetacentrics, or subtelocentrics. "Typical" specimens of T. umbrinus have 2n=78, 62 acrocentrics and minute chromosomes, with the remainder being biarmed. However, populations of T. bottae from within 100 miles of the Patagonias display considerable variation in the number of acrocentrics — one population from less than 50 miles away has 18 acrocentrics. One wonders how great the variation in number of acrocentrics might be throughout the range of T. bottae, judging from the amount of morphological variation. Only three populations of one subspecies of T. tmd^rinus was studied and the variation was minor. Employment of characters. — Each character listed above displays overlap between the two species. In dorsal coloration, number of pectoral mammae, and 86 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. bof foe- like umbrinus 42 5 botfae 48 27 I 5 4 2 2 0 3 8 4 4 7 2 5 16 0 c 6 9 1 0 c o 5 7 9 1 U o 8 6 0 « 0 c 0 9 3 0 E U) o o 10 2 0 >. o t/) a. 11 2 0 / n f e r m e d rP =4' i a tf A f u m brinus -like 1 33 8 13 1 0 1 0 3 J 2 2 2 12 2 5 2 3 7 5 0 3 7 0 7 1 3 0 0 0 0 1 2 7 3 0 0 7 0 Fig. 9. Shape of the maxillo-frontal suture (arrow). It is concave in hottae, straight or convex in uuibrinus, or intermediate. The specimens are scored as in Fig. 8. length of baeulum, there is least overlap. Scatter diagrams were prepared for nearly all combinations of characters, including color as coded, but there was no obvious means of separating T. hottae and T. umbrinus in the area of this study by use of these diagrams. The use of all characters in combination is necessary if the two are to be distinguished. Using a computer program BIMD 05 as modified by Charles Thaeler (1968), employing discriminant coefficients, 16 characters were used in the analysis for males (including length and height of head of baeulum) and 15 for females. The discriminant function coefficient was determined for each character and these summed for each specimen. The values for male T. hottae range from 5.822 to 6.450 and for male T. timhiinus from 4.102 to 5.018. The values for the male pocket gophers from Sycamore Canyon localities 1 to 11 (Fig. 10) range from 3.514 to 6.581. Some are well within the range of one or the other species and some fall between the two. The \alues for female T. hottae range from 4.452 to 5.444 and for female T. umhrinus from 2.064 to 2.870. The values for the female pocket gophers from localities 1 through 11 range from 1.614 to 5.373. The values for the males and females are corrected to correspond and both are plotted on one graph (Fig. 10). T^^'enty-nine speci- mens in Sycamore Cainon tall between the range of the samples of the t\vo species and this suggests that these specimens are hybrids or intergrades (see Fig. 10 and Table 2). HOFFMEISTER ThOMOMYS IN ARIZONA 87 Independently of the al)o\e procedure, another approach was undertaken. The relationships of the specimens were determined by taxonomic distance coefficients ( Sokal and Sneath, 1963:147, 300). The same characters were employed as in the analysis liy the discriminant function coefficients. In using these taxonomic distance coefficients, the lesser the distance between two, the greater their phenetic relationship. Each specimen was judged to be a T. hottae, aberrant bottae, hybrid, aberrant umhriniis, or T. itmbrinus. The results of this analysis, listed b\- localit>', are shown in Table 2. Note that the results from _ „.4-- ry-'-^ n 1_J L j_ , r "■'1 :1 1" " 1 )»^ , I umbrinus -hybrid Fig. 10. Distribution of pocket gophers from Sycamore Canyon, Patagonia Mts., as determined by discriminant function coefficients. Light diagonal lines are T. hottae. dots are T. tnnhrimis. and hea\y diagonal lines represent various localities within the Canyon. Each square represents one individual. The hybrids are indicated. this analysis do not differ greatly from those of the analysis by the discriminant function coefficients or the next analysis made. It should be noted that the sample sizes may differ in the different analyses. Still another procedure was employed to segregate T. bottae or T. iimhnmis. A lower or upper limit of the range of variation was set at two standard devia- tions. For males, 11 characters were used — color, length of baculum, three external, four cranial, and position and shape of the maxillo-frontal suture. For females, 10 characters were used, with the one for length of baculum omitted. Each character for each specimen was scored, as bottae if it fell within two standard de\iations of the known sample of T. bottae, or T. unibrintis, or intermediate. The result was that a male specimen might be scored as 10/11 hottae (=10 characters bottae-\\ke) and 1/11 intermediate, and regarded as T. hottae; or 4/11 bottae, 5/11 umbrinus, 2/11 intermediate, and regarded as a hvbrid. The results of this analysis are given in Table 2. Although the con- cordance of this system with the others is not so great as between the first two, and one \\'ould not expect it to be, there still is considerable similarity. Discussion A large number of the specimens from Sycamore Canyon are intermediate between T. hottae and T. umbrinus (Table 2). These are from "intermediate" localities also. It seems apparent that there is hybridization or intergradation between the two species. From localities 1 through 11 within the Canyon, 29 specimens are "inter- mediate" as determined by the discriminant function analysis. Using the taxonomic distance coefficients, 21 specimens are "inter- 88 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 2. — Placement of pocket gophers from the 11 localities in Syca- more Canyon (nos. 1 through 11) as to one or the other species or as "intermediate" using three different methods of analysis. T. bottae 123456789 10 II T.umbrinus Discriminant Function Analysis bottae hybrid umhrinus 44 5 2 2 6 9 2 8 1 5 10 3*- 4 1 13 9 7 12 Ta.xonomic Distance Coefficient bottae "aberrant' hybrid "al^errant' umhrinus 37 5 2 2 2 2 9 2 1 5 3 1 4 2 11 1* 3* 1 2 3 3 13 10 7 8 Two Sta ndard Deviations bottae "alierrant' hyl^id "aberrant' umhrinus 36 1 5 1 1 2 6 1 5 1 3 6 1 2 4 1 12 1* 2* 4 1 1 13 10 7 10 1 32 26 26 " These may not be from locality 6, and perhaps should be identified with a lower locality. mediate" and an additional 22 are regarded as aberrant (possibly hybrids, or possibly referable to a species ) . Using the 2 SD method, 21 specimens are regarded as "intermediate" and an additional nine as aberrant. In parts of the Patagonia Mountains, Thomomijs bottae and T. uml)rinus\ which are usually allopatric, ha\'e not evolved effective genetic isolation. Where the two groups of populations make sec- ondary contact, either sympatrically or in allopatric zones, intro- gressive hybridization occurs. In Sycamore Canyon, at locality 1 and below, all specimens are T. bottae; at locality 8 and above, all are T. umbrinus. From localities 2 through 7, a distance of less than three miles, there are to be found T. bottae, hybrids, and T. um- brinus. Most of the hybridization occurs between locality 6 and a place one-half mile below locality 3, a distance of about one and a half miles. This is approximately the same area where Patton and Dingman ( 1968 ) found four hybrids in Sycamore Canyon. The zone of hybridization seems well marked but narrow. On the basis of karyology, nine specimens from Sycamore Can- yon are hybrids or backcross hybrids. These are from a narrow zone also — localities 2 through 7. Four of these hybrids have been re- ported upon and discussed by Patton and Dingman ( 1968 ) . One is regarded as a Fi hybrid, three as backcrosses. Five specimens that were karyotyped by M. R. Lee and E. Zimmerman indicate that HOFFMEISTER ThOMOMYS IN ARIZONA 89 three are Fi hybrids and two are probably backcrosses. Of these five, three are from locaHty 3 and two from two tenths of a mile below locality 3. A basic consideration is whether, in southern Arizona, T. hottae and T. timbrinus are distinct species. Samples of gophers taken from the Santa Cruz River Valley and from the upper parts of Sycamore Canyon, a distance of only eight miles, would leave little doubt but that the samples were from distinct species if collections were not available from the inter\'ening area. But such questions arise as these: (1) Are all gophers that live on poor, rocky soil of small size (umhrimis-like)? Often they are small, but do not have the other characteristics of umbrinus. (2) Do small-sized gophers frequently have but one pair of pectoral mammae (iimbrinus-like)? There is no evidence that such is the case. ( 3 ) Do gophers that live at higher elevations ha\'e a darker dorsal coloration? Frequently at higher elevations the soils are darker and so are the gophers, but the dark color is not necessarily restricted to a middorsal band as in um- brinus. T. bottoe and T. umbrinus are judged on chromosomal distinctiveness as two species in Arizona (Patton and Dingman, 1968 ) . Yet, in view of the survey of the variation in the karyology of only a few T. bottae in Arizona, are the differences great enough to regard these as distinct species? Probably, but further evidence will be needed. With all of the evidence here marshalled, it still is a matter of interpretation as to whether the populations of bottae and umbrinus in southern Arizona are subspecificalh' or specifically distinct. I would interpret the evidence as indicating that they are distinct species, with introgressive or allopatric hybridization occurring in a narrow zone in one place in southern Arizona, and possibly in several other areas where the range of the two species come to- gether, and especially where it has been difficult to assign specimens to one or the other species. The narrowness of the zone of hybrid- ization, in spite of the extensive interchange of genetical material within this zone, would suggest specific difFerentiation. Admittedly, the suggested presence of backcross hybrids, based on karyology, and the seeming vigor of these and other hybrids, may argue against specific status. Does this hybridization that occurs at one place, and perhaps several places, represent the incipient formation of two species or rather the infrequent intermingling of genetical material of two established species? Although difficult to decide, I would guess the 90 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. latter. The allopatric distribution of umbrinus-\ikc gophers and hottae-\ike gophers over large areas ( Fig. 1 ) suggests that these two evolved independently. In at least one place where the two species come together, allopatric hybridization occurs with nearly complete genetic interchange and backcrossing, yet the parental populations maintain their identities. The situation in Sycamore Canyon, Arizona, seemingly fits the definition of Remington's suture-zone hybridization, judging from the summary of Yang and Selander (1968:139). There is extensive hybridization in a narrow zone between morphologically dissimilar, allopatric populations. There is backcrossing with no reproductive isolation or hybrid inferiority. Despite interbreeding and back- crossing, introgression of genes into the parental population is limited. Where the species Tlwmojmjs hottae and T. umbrinus live sympatrically, be it Sycamore Canyon or the few other places throughout their ranges, even though there may be only partial ecological and reproductive isolation between the two, the area of contact is so small that swamping does not occur. Summary In places in southeastern Arizona, Thomomijs hottae-\\Ve go- phers and Thomomys wnbrinus-like gophers ocur together or within a few yards of each other. Characters useful in distinguishing these two species elsewhere will not serve here for some animals have some characters of both species. Three analyses of the population in Sycamore Canyon, west side of the Patagonia Mountains, were made using discriminant function analysis, taxonomic distance co- efficients, and two standard de\'iations of each side of the mean. Characters employed were dorsal coloration, number of pectoral mammae, length of baculum, various external and cranial measure- ments, and position and shape of the ma.xillo-frontal suture relative to the lacrimal. These analyses indicate that somewhere between 21 and 29 specimens, out of 109, are intermediates or hybrids. Within a 3 mile area of contact, at intermediate elevations within Sycamore Canyon, extensive hybridization, not intergradation, occurs between the two species, T. bottoe and T. umbrinus. Acknowledgments Numerous persons liiue assisted and advised with the computer analysis of these data. I should especially like to thank Dr. Charles Thaeler, New Mexico State University, and Dr. Da\ id Eades and Dr. Richard Selander, University of Illinois. John Lynch measured most of the skulls; Harry Henriksen prepared HOFFMEISTER ThOMOMYS IN ARIZONA 91 the illustrations. Dr. James Patton, then at the University of Arizona, loaned the material he reported upon. Earl Zimmerman and Dr. Raymond Lee prepared chromosome smears and photomicrographs. Without the skill and perseverance in collecting by Woodrow and Lois C.oodpaster, this study would not ha\e been possible. The National Science Foundation supported much of this research on grant GB-1432. Literature Cited Anderson, S. 1966. Taxonomy of gophers, especially TJwiuomijs in Chihuahua, Me.xico. Syst. Zool., 15:189-198, 6 figs. Bailey, V. 1915. Revision of the pocket gophers of the genus Thomomys. N. Amer. Fauna, 39:1-136, 8 pis., 10 figs. Bakeh, R. H. 1953. The pocket gophers (genus Thomomys) of Coahuila, Mexico. Univ. Kansas Publ, Mus. Nat. Hist., 5:499-514, 1 fig. Blair, W. F. 1939. New mammals from Texas and Oklahoma, with remarks on the status of Thomomys texemis Bailey. Occas. Papers Mus. Zool., Univ. Michigan, 403:1-7. Davis, W. D., and H. K. Buechner 1946. Pocket gophers (Thomomys) of the Davis Mountains, Texas. Jour. Mamm., 27:265-271, 2 figs. Dunnigan, p. B. 1967. Pocket gophers of the genus Thomomys of the Mexican state of Sinaloa. Radford Rev., 21:139-168, 4 figs. Goldman, E. A. 1947. The pocket gophers (genus Thomomys) of x\rizona. N. Amer. Fauna, 59:1-39, 2 figs. Hall, E. R., and K. R. Kelson 1959. The mammals of North America. Ronald Press, New York, l:xxx -f 546 + 7.9, illustrated. HOFFMEISTER, D. F., AND W. W. GOODPASTER 1954. The mammals of the Huachuca Mountains, southeastern Arizona. Ilfinois Biol. Monog., 24 :v + 152, 27 figs. Mearns, E. a. 1897. Descriptions of six new mammals from North America. Proc. U.S. Nat. Mus., 19:719-724. Nelson, E. W., and E. A. Goldman 1934. Pocket gophers of the genus Thomomys of Mexican mainland and bordering territory. Jour. Mamm., 15:105-124. Patton, J. L., and R. E. Dingman 1968. Chromosome studies of pocket gc^^hers, genus Thomomys. I. The specific status of TJiomomi/s umbrinus (Richardson) in Arizona. Jour. Mamm., 49:1-13, 8 figs. SoKAL, R. R., AND P. H. A. Sneath 1963. Principles of numerical taxonomy. W. H. Freeman and Co., San Francisco and London, xvi -|- 359 pp., illustrated. Thaller, C. S., Jr. 1968. An analysis of three hybrid populations of pocket gophers ( genus Thomomys,). Evolution, 22:543-555, 3 figs. Yang, S. Y., and R. K. Selandfr 1968. Hybridization in the grackle Qiiisccdus qiiiscula in Louisiana. Syst. Zool., 17:107-143, 19 figs. RESTOS FOSILES DE MAMIFEROS DE TLAPACOYA, ESTADO DE MEXICO (PLEISTOCENO-RECIENTE) FOR TicuL Alvarez Las excavaciones realizadas por el personal del ]3epartamento de Prehistoria, Institute Nacional de Antropologia e Historia, en el cerro de Tlapacoya, Mexico, durante los afios de 1966 y 1967, han proporcionado una gran cantidad de huesos de vertebrados, siendo por ello hasta el momento, una de las mas iniportantes localidades para el conocimiento de la Fauna Pleistocenica de la parte central de Mexico, conocida como Valle de Mexico. Estas excavaciones son tambien muy valiosas porque por primera vez se tienen de esta region de Mexico, fechas de C^\ que nos dan una idea de cuando dichas faunas existieron y haran posible futuras correlaciones, tanto con descubrimientos del pasado, como con los descubrimientos venideros. La fauna estudiada y que dio origen a este trabajo se limita a los mamiferos encontrados en las excavaciones del aiio de 1966, realizadas por los Arqueologos Elizabeth y Mickael Goodlife, quienes laboraron para el Departamento de Prehistoria. Ademas de los fosiles de mamiferos, se rescataron gran cantidad de huesos de aves, que son objeto de minucioso estudio por parte del Dr. Allan R. Phillips del Institute de Biologia de la Universidad Na- cional Autonoma de Mexico, y del Dr. Pierce Brodkorb de la Universidad de Florida. Las excavaciones se realizaron en la falda sureste del cerro de Tlapacoya, a 1.5 kilometres al sur del pueblo del mismo nombre (113° 02' 40" long. E y 19° 17' 49" lat. N), estado de Mexico y que a su vez se encuentra a 26 kilometres al Sureste del centre de la Ciudad de Mexico (Fig. 1). Los hallazgos se llevaron acabo en dos calas e trincheras denominadas respectivamente alfa y beta, situadas a 37 metres una de la etra. La cala alfa tenia 30 metres de extension y anchura entre dos y tres metres. La capa principal donde se encontraron los huesos fue denominada con los numeres XLI a XLII. La trinchera beta niidio 53 metres de large y de dos a cuatro metres de anche. La capa en la que se encontro mayor numere de restes oseos fue de cenizas volcanicas, que se encentraba en contacte con la roca madre. La capa de ceniza se denemino con el numere XLVL (93) 94 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 9 ?^ S8» SO' 19° 30 I 9« ' \ _^ -'" "^^ r' ' ' ^\ HIDALGO \ MEXICO ,- ,' / ___• x , / / ©Toluca ( MexicoP 'v TLAXCALA Ayotia '-_^^^'\ TIaxcala ° Tlapacoya \ ^^^- \ \ ^ 1 • Distrifo j Federal\ \ \ \PUEBLA V "^--^ ; Pueblal^ ) MORELOS 1 / 1 I9"> 30' 19° 99° 9e°30> 9e»55' I9°I8' Kilometre IS'IS' 98° 55' Fig. 1. Mapa del area y sitio exacto de las excavaciones. La estratificacion do las trincheras es muy complicada, habien- dose dividido hasta en 54 diferentes estratos (Goodlife y Goodlife, 1969); sin embargo, solo dos son importantes desde el punto de vista paleontologico, porque en ellos se encontraron la mayor parte de los restos oseos (Fig. 2). Alvarez — Pleistocene Fossils from Mexico 95 El mas mock'ino se encontro en la trinchera alfa y se supone haya sido un hogar del honibre prehistorico por la gran acumula- cion de huesos, principalmente de mamiferos grandes, asi como por haberse enconlrado un area linipia, con carbon y grandes piedras alrededor (Goodlife y Goodlife, 1966). Los restos de carbon de este lugar ban sido fechados por C^^ en 24,000 ± 4000 aiios antes del presente (Haynes, 1967). El otro estrato en que se encontraron gran numero de huesos, es ceniza xolcanica en contacto con la roca del cerro. No existe fecha de material de esta capa, pero suponemos que sea alrededor de los 30,000 anos, ya que la muestra de una capa superior a la de cenizas data de hace 24,200 + 500. Madera carbonizada 22,200+ 2.600 Huesos de mami'feros en limo amorlllo (Copas XLI-XLII < ) Madera descompuesta 24,200+ 500 Superficie artificial Ceniza volcdnica de grano mediono , amarillo claro y gris Roca volca'nfca de grano fino con fenocristales negros Aglomerado volcanico grueso de cenizas, cantos y huesos (Capos XLVI /3 ) Fig. 2. Estiatigrafia generalizada de los calas alfa y beta de Tlapacoya (66-1), basada en la de Haynes (1967), con modificaciones. Los restos de esta capa estan constituidos principalmente por aves y pequeiios mamiferos, aunque tambien existen algunos restos de animales de mayor tamaiio. 96 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Los ejemplares que forman la base de este estudio se encuentran catalogados en el Laboratorio de Paleozoologia, del Departamento de Prehistoria, Institiito Nacional de Antropologia e Historia (DP). Dos mandibulas de la nueva especie de Odocoileus aqui descrita, se encuentran en la coleccion de Paleontologia de Vertebrados de la Smithsonian Institution. Si no se especifica de otra manera, todas las medidas estan en milimetros. Agradezco al Prof. Jose Luis Lorenzo, Jefe del Departamento de Prehistoria su sugerenica y ayuda para realizar este trabajo. A la arqueologa Lorena Mirambell, encargada del proyecto de Tlapa- coya, por su valiosa cooperacion para aclarar diferentes problemas estratigraficos y de otra indole. A los arqueologos Elizabeth y Mickael Goodlife por ser ellos quienes realizaron las excavaciones y pusieron todo su empeiio por rescatar los materiales oseos en el mejor estado posible. En especial agradezco al Dr. Clayton Ray de la Smithsonian Institution por sus valiosas sugerencias respecto a la identificacion del material estudiado. Al Dr. J. R. Macdonald del Museo de Los Angeles County por el prestamo de varias piezas de "Sangamona" de San Josecito, Nuevo Leon. Lista de Especies Chiroptfra Phyllostomatidae Mormoops megalophylla (Peters, 1864) Material— Humero (928 DP). El hueso fosil encontrado en Tlapacoya, no difiere en nada de los usados para su comparacion, por lo ciial se identifica conio Mormoops megalophylla, murcielago muy abundante en las zonas bajas de Mexico, pero que no se ha registrado del Valle de Mexico en epocas lecientes. La capa de donde proviene tiene antiguedad mayor a los 24,000 anos antes del presente y se encuentra justamente arriba de las capas formadas por cenizas de la erupcion volcanica. Lagomorpha Leporidae Sylvilagus cunicularius (Waterhouse, 1848) Material— CaMneo (929 DP). El calcaneo se ha identificado como perteneciente a la especie S. ctmicu- larius, con base en su tamaiio, que es realmente mayor que el de S. ftoridamis Alvarez — Pleistocene Fossils from Mexico 9/ o que Romerolagus, los otros dos Leporidae que existen en el valle de Mexico. S. cunicitlarius es todavia un conejo muy aliundante en todo el sur del altiplano mexicano, extendiendo su distribucion hasta las costas de Sinaloa. Medidas: longitud del hueso 26.4; ancho maximo del mismo, 11.3. Como fosil se ha registrado de Veracruz ( Dalquest, 1961). El calcaneo de Tlapacoya tiene antiguedad aproximada de 12,000 anos ye se encontro, for- mando parte de el un conjunto de huesos de un hogar, en la cala alfa. Sylvilagus floridanus (J. A. Allen, 1890) Material. — Fragmento de mandiiiula con pm2-m2 (930 DP). Al contrario del calcaneo anterior, este material se identifico como S. floridanus por se menor tamaiio. Al compararlo con mandibulas de floridanus no encontramos diferencias palpables en cuento a forma y tamano, no siendo asi con S. cunicularius que si bien la forma no difiere, el tamaiio de cunicularius es notablemente mas grande. S. floridanus es un animal que ha sobrevivido a la presion demograiica del Valle de Mexico y todavia es posible encontrarlo con cierta facilidad. La mandibula de S. floridanus fue encontrada en la capa de ceniza de la erupcion volcanica, que se calcula de una antiguedad mayor a 24,000 aiios. RODENTIA Geomyidae I Pappogeomys sp. Material. — Fragmento de mandibula, con i-m2, sin procesos; ibid., sin incisi\'o; fragmento maxilar y premaxilar con incisivo (936-938 DP). Debido a lo fragmentado y escaso del material, nos ha sido imposible poder determinar la especie de los restos de tuzas encontrados en Tlapacoya, con antiguedad mayor a los 24,000 anos; sin embargo, si creemos que el genero este bien determinado ya que los incisivos superiores presentan el surco medio tan caracteristico de este genero. A juzgar por el tamano, los fosiles de Tlapacoya no pertenecen a ninguna de las especies que actualmente viven en el Valle de Mexico, de los cuales Tappogeomys merriami es la mas grande y la que habita actualmente en el area de donde se rescataran los fosiles, la otra especie P. tylorhinus es mas pequena y habita al noroeste del Valle de Me.xico. En la Figura 3 se compara el ancho de los incisivos inferiores y la longitud del premolar del fosil, con ejemplares de P. merriami y P. tylorhinus viendose que el fosil queda por abajo, de las medidas de los adultos de merriami y tylorhinus y solo es igual que algunos ejemplares muy jovenes de las especies citadas. Cualitativamente, el caracter que mayor significado tiene y por el cual no hemos querido asignar los ejemplares de Tlapacoya a una de las especies vivientes, principalmente de las del Valle de Mexico, es que el surco medio de la cara frontal del incisivo esta mas afuera de la mitad de la cara del incisivo, de tal manera que la porcion interna (1.4) es el 127.2 por ciento de la porcion externa ( 1.1 ) (Fig. 4A). En 20 ejemplares de P. merriami tomadas al azar (en 98 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. cuanto a edad y sexo) la media es 96.3 por ciento, con 111.1 a 80.0 de varia- cion y en 18 ejeniplares de P. tylorhimis es de 97.6 (102.0-85.2) por ciento. Otro caracter se presenta en el premolar inferior, en el cual el angulo entrante externo que separa a los dos lobulos que forman el diente, presenta una proyeccion interna y hacia adelante (Fig. 4B). Esta proyeccion no la hemos encontrado tan bien marcada en ninguno de los 50 ejemplares de P. merriami y P. tylorliinus que hemos examinado, aunque si se encuentra en muchos de ellos una indicacion de dicha proyeccion. Sin embargo, considera- mos que la variacion en este respecto puede ser mayor, por lo que su signifi- cado taxonomico se desvanece. Merriam (1895) coloca dentro de los generos que poseen el surco medio del incisivo en la parte externa a Geomys y Zygogeomys, dos generos que presentan dos surcos en vez de uno como sucede entre otros Pappogeomys. El autor antes citado no menciona nada al respecto de la variacion de los angulos en el premolar inferior. mm ANCHO DEL INCISIVO 5 0 _ INFERIOR • • • 8 " • •• • • • »» • • • ■ 6 - •• • .4 • • • • • • • *• - • • • • • • • • • • • .2 - • • • t • • 40 .8 - • • • ♦ • t • t t • .6 .4 - • * • ♦ t • u • t. * • • 2 30 ♦ ♦ t * ♦ * ♦ • .8 .6 - fosil ♦ • ♦ • • .4' •* 2.2 ' _L + 1 1 1 1 1 1 1 1 3.2 6 .8 4.0 .2 4 LONGITUD DEL PREMOLAR INFERIOR 5.0 mm Fig. 3. Grafica de la relacion entre el ancho del incisivo inferior y la longitud del premolar inferior en Pappogeomys. Los puntos representan medidas de P. merriami y cruces de P. tylorhinus. Considerando que el material fosil de Tlapacoya no coincidio en elgunas caracteristicas con las especies del Valle de Mexico, preferimos asignar este material solo al genero Pappogeomys, esperando que e.xista mas material, tanto fosil como viviente, para poder determinar si se trata de una especie no descrita o bien, solo un extremo de la variacion de alguna de las especies actuales. Alvarez — Pleistocene Fossils from Mexico 99 Cricetidae Peroniyscus maldonatloi Alvarez, 1967 Material. — Fragmento de mandihula derecha, sin procesos ni horde inferior de la rania, ni la mitad posterior de m3 (1153 DP). Tomando en consideracion el taniano de la mandihula, asi coino los pocos caracteres que se puden apreciar en la mandilnila procedente de Tlapacoya, esta es muy semejante tipo de Peromijscus maldonadoi espeeie descrita del Pleistoceno de Teqnesquinahua, Mexico. En la estructura y tamano de los molares encontramos tanihien mucha similitud. La serie de molares inferiores mide en el tipo de P. maldonadoi 5.8, igual que en el ejemplar de Tlapacoya. Aunque la estructura de los molares en el tipo de P. maldonadoi no se puede apreciar en detalle, dehido al desgaste de los mismos, si es posihle apreciar que existe una similitud en la forma general entre este ejemplar y la del de Tlapacoya que es mas joven; asi, el segundo molar es relati\amente grande y cuadrado en amhos ejemplares. La linica diferencia aparente es la ausencia de ectostilidio en el tipo de P. ?»a/- ont. 936 DP 937 DP 938 DP 1 mm 1 mm Fig. 4. A, corte transxersal del incisivo superior del Pappogeomtjs fosil; B, premolares y molares del Pappogeomtjs fosil; C, primero y segundo molares de Peromijscus maldonadoi. 100 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. donadoi y que si esta bien desarrollado en el ejemplar de Tlapacoya, especial- mente en el primer molar, ya que en el segundo dicha estruchira no esta bien maicada (Fig. 4C). Sin embargo, esta diferencia no es de tomarse mucho en cuenta ya que segun Hooper (1957) la presencia de stilos y lofos es muy variable en las especies de Peromtjscus. Debido a la semejanza de estructura de la mandibula procedente de Tlapacoya, con el tipo de P. rnaklonadoi, asi como que ambas proceden de localidades muy cercanas y de depositos Pleistocenicos, consideramos que sean de la misma especie. Tlapacoya se encuentra a 42 kilometres al sureste de Tequesquinahua, Mexico y el estrato en que se encuentra la mandibula de Tlapacoya fue fechado en mas de 24,000 aiios; aunque del tipo de P. mal- donadoi no tenemos la edad, suponemos que proviene del Pleistocene por el tipo de fauna con que se encontro asociado (Alvarez, 1967). Para completar mas la diagnosis de la especie P. rnaldonadoi, describiremos a continuacion la estructura de los molares del ejemplar de Tlapacoya, siguiendo la terminologia dada por Hooper (1957). El primer molar presenta proto- conidio dividido en la parte anterior y con el doblez menor bien marcado; el mesostilidio unido por medio del mesolofidio a la cara anterior del entoco- nidio; cingulo posterior sin llegar al borde interno del molar; con ectostilidio, pero sin ectolofidio. El segundo molar presenta el cingulo anterior extendido hasta el borde externo del molar, ectostilidio poco desarrollado, sin ectolofidio; mesolofidio unido al ectoconidio en su parte anterior, sin mesolofidio; cingulo posterior extendido hasta el borde lingual del molar y continuandose en cierta forma con el borde del ectoconidio. La estructura de los molares, asi como el tamano de los mismos es muy parecido a P. zarhinchus, del cual difiere en que el primer pliegue primario tiene direccion oblicua al eje longitudinal del molar, ademas de ser mas profunda. Medidas del ejemplar de Tlapacoya: longitud de la serie de molares, 5.8; longitud de ml, 2.23, ancho, 1.43; longitud de m2, 1.82, ancho, 1.50. Neotoma mexicana Baird, 1855 Material. — Primer molar inferior izquierdo (939 DP). El molar difiere en algunos detalles de los 10 ejemplares usados para com- paracion, pero la variacion entre ellos es muy grande, de tal manera que consideramos que las diferencias entre el molar de Tlapacoya, que ademas no son constantes, y todos los otros molares, sean mas bien de caracter individual que especifico. Freudenberg (1922: 104) enlisto restos de Neotoma del Valle de Mexico, sin mencionar las especies ni dar ninguna medida o figura que nos pudiera dar una idea de que especie se trata. Alvarez (1967) describio N. magnodonta del Pleistoceno del Valle de Mexico, que difiere de N. mexicana en varios caracteres morfologicos y sob re todo en su mayor tamaiio. Los restos aqui registrados como iV. mexicana, se encontraron formando parte de la concentracion mayor de huesos de la cala beta, que se supone fueron depositados por el hombre hace unos 24,000 anos. Existe la posibilidad de que el molar de Neotoma haya llegado hasta el hogar por acarreo a traves de los tuneles de tuza. Alvarez — Pleistocene Fossils from Mexico 101 Microtus mexicanus (Saussure, 1861) Material. — Mandibula con incisivo, ml-2. Sin proceso angular y coronoide (940 DP). La linica diferencia con las mandihulas que se usaron para comparacion, estriha en que el fosil es ligeramente mayor. Procede del area del hogar y presenta la misma posibilidad que el molar de Neotoma. Neochoerus pinckneyi Hay, 1926 Material. — Primer molar izquierdo inferior (941 DP). El molar de carpincho encontrado en Tlapacoya, tentativamente se asigna a AT. pinckneyi, especie que se ha registrado en America del Norte. Actualmente se esta realizando un estudio del Material de Carpinchos que proviene de Chapala y Zacualco, Jalisco y en el que se ha encontrado una variacion tan grande en la forma y medida del premolar inferior, que nos hace pensar que los diferente^ generos de la familia Hydrochoeridae son variacion de un misnio ta.xon y que por lo tanto, muchas especies deberan ser puestas en sinonimia. La corona del molar de Tlapacoya mide de largo 9.8 y de ancho, 6.9 y procede de la capa mas profunda que se excavo o sea la de cenizas volcanicas. Carnivora Canidae Canis sp. Material. — Un fragmento de mandibula, sin ningun diente (942 DP). Aunque la falta de dientes hace mas dificil la identificacion de este frag- mento, la consideramos como Canis por la forma del borde inferior de la mandibula; posicion de la fosa coroidea del alveolo de m3, caracteres que no difieren de las mandibulas de Canis lupus, C. Intrans, C. familiaris con que fue comparado. Se encontro este fragmento en la capa de ceniza volcanica, que data de mas de 24,000 anos. Ursidae Ursus americanus Pallas, 1780 Material. — Craneo fragmentado, dos mandibulas; dos femures; tibias izquierda y derecha; pelvis fragmentada; fragmentos de escapula izquierda; calcaneo, uno completo y otro roto; astragalo; ocho vertebras; 12 falanges; dos ulnas fragmentadas y dos radios (950-976 DP). Todos los materiales identificados como de oso se encontraron en una misma capa y muy juntos entre si, por lo que suponemos que se trate de un solo individuo. La comparacion de las medidas de los molares del ejemplar de Tlapacoya con los dados por Kurten (1963:5) para 25 ejemplares de Ursus americanus del Reciente, nos muestra que nuestro ejemplar se aparta ligeramente de la amplitud dada por dicho autor. P4, M2, m2, y m3 son menores, en cambio M2 y p4 son mayores que el maximo de la variacion dada por Kurten (op. cit.). 102 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Tomando en cuenta las medidas de Stock (1950) para una mandiliula de U. ameiicanus de la ciieva de San Josecito, Nuevo Leon, la mandiljiila de Tlapacoya, es im poco mayor, pero los dientes son notablemente mas pequenos. Stock (op. cit.) identifica como U. ameiicanus el oso de San Josecito, aunque senala sn parecido en la denticion con U. optimus, especie del Pleistoceno de California caracterizado por sn robiista dentadura. El ejemplar de Tlapacoya creo que sea tipico U. americanus, aunque posiblemente una subespecie mas pequeiia que los actualmente conocidos. Los huesos del oso se encontraron formando la mayor parte del grupo designado como hogar en la cala alfa y como ya se indico, data de 24,000 aiios aproximadamente. Procyonidae Procyon lotor (Linnaeus, 1758) Material. — Mitad anterior de mandibula, desde el borde posterior de ml, con pm4 y ml. Fragmento maxilar con ah'eolo de Ml y con el M2; mitad inferior del humero; mitad inferior de tibia; un astragalo; tercio superior de ulna (943-948 DP). La mandibula pertenecio a un individuo joven, sin embargo, tanto esta como los restos postcraneales son ligeramente de mayor tamafio que los usados para comparacion. Esta diferencia probablemente se deba a distinto desarrollo o sexo del material comparado. Los restos de Procijon fueron encontrados en tres capas dife rentes. La mas antigua corresponde a las ceni/as \'olcanicas de la cala beta, que como ya se ha indicado, data de mas de 24,000 anos; otros restos se hallaron en la aglomera- cion de huesos y piedras denominada como hogar y cjue tiene una edad de 24,000 aiios y por ultimo, se localizaron algimos restos en capas mas super- ficiales que las del hogar, que corresponden a una aproximada de 8000 a 9000 anos. Mustelidae Lutra canadensis (Schreber, 1776) Material. — Fragmentos de un craneo: region jjasal; frontales; pterigoides, maxila izquierda con la carnacia "//; situ" y alveolos de premolares y molares (949 DP). Se comparo con cuatro craneos de ejemplares recientes y se encontro que difiere solo en pequeiios detalles, como presentar el talonoide de la carnacia mas angosto; el borde posterior del mismo es ligeramente concavo en contra de convexo en los actuales. EI taniaiio del carnacia es mas pequeiio que en los ejemplares de comparacion que presentan el mismo desgaste en el diente. Medidas del carnacia del fosil, seguidas de las de dos ejemplares recientes: largo, 12.2, 14.1, 12.2; ancho 10.0, 11.9, 10.2. Este genero no se habia registrado anteriorme ite en el Pleistoceno mexi- cano, ni tampoco se conoce del Reciente en el Valle de Mexico. Los restos de Lutra de Tlapacoya fueron rescatados en el mismo ni\'el que los de Neo- choerus o sea el estrato mas profundo, formado por los depositos de una erupcion volcanica. Alvarez — Pleistocene Fossils from Mexico 103 Ahctiodactyla Cenidae Odocoileus virginianus (Zimmermann, 1780) Material. — Rama mandibular derecha con dientes; mitad posterior de la mandibnla derecha desde el primer premolar; astragalo; region parietal muy fragmentada, con la base de las astas; tres falanges segundas; dos falanges primeras completas y dos mitades; fragmento de calcaneo; articulacion inferior de la escapula; fragmento basal de asta con nna pnnta; dos femures completos; metatarso, dos mitades superiores de metatarso; atlas (977-1000, 1151-1152 DP). Todo el material que se refiere a Odocoileus virginianus se identifico como tal, con base principalmente en el tamafio, ya que cualitativamente no difiere del material asignado a la especie de Odocoileus aqui descrita y que es de mucho mayor tamaiio. Los restos de O. virginianus se encontraron en diferentes capas; sin embargo, la mayor frecuencia esta en la capa mas profunda, tanto en la cala alfa, como la beta que pertenece a la erupcion volcanica. Existen restos en una capa de la cala beta, situada por arriba de la playa, que se ha fechado en 22,200 aiios, pero por abajo de la otra capa fechada en 14,000 anos de antiguedad. Por ultimo, encontramos tambien algimos restos de \enado cola blanca en el hogar y otros pocos en la capa mas superficial. Odocoileus halli, especie nue\'a Holottjpo. — Mandibula izquierda y derecha del mismo ejemplar procedente de la capa XLII de la trinchera alfa de Tlapacoya, Mexico, y catalogada con los numeros 1082 y 1083. Departamento de Prehistoria, Instituto Nacional de Antropologia e Historia. Mandibula derecho completa, sin incisixos, ni tercer molar, sin proceso coronoide; mandibula izquierda con los premolares y molares, sin incisivos, le falta la region desde el ultimo molar hacia atras (Fig. 5). Paratipos. — Ocho mandibulas sin incisivos pero con premolares y molares; una rama mandibular sin dientes; cuatro series de dientes superiores con fragmento del maxilar, 15 premolares y molares sueltos; region posterior del craneo, con la base de las astas; parietales de ambos lados con la base de las astas; region parietal; tres fragmentos de asta; numerosos elementos post- craneales (1001-1150, 1177-1180, 1191 DP). Edad. — Pleistoceno-Reciente, fecha de C 14 de 22,000 ± 2600 anos. Diagnosis. — Tamaiio grande para el genero, longitud alveolar de la man- dibula de 104 a 115; maxilar, 117.3. Forma de los premolares y molares igual a Odocoileus virginianus, crestas de la cara lingual de los premolares y molares bien desarrollada; segunda mitad de pm4 menos de la mitad de la anterior; la mayoria de los molares con un estilo entre los dos lobidos externos. Description de los Molares La descripcion de las estructiuas molares esta basada en tres ejemplares que presentan desde el que no tiene desgaste alguno hasta el ejemplar viejo, con los molares muy desgastados (Fig. 5). 104 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 1147 DP Fig. 5. Molares y mandibula de Odocoileus halli. De arriba hacia abajo, primero una serie compuesta de premolares y molares superiores (1147, 1102, 1191 DP); serie de dientes superiores con menos desgaste (1117 DP); vista lingual de los dientes (1117 D.P. ); vista oclusal de una serie de molares in- feriorcs (1119 DP); vista de los molares inferiores izquierdos del tipo (1083 DP) y de la mandibula derecha del tipo (1082 DP). I Alvarez — Pleistocene Fossils from Mexico 105 Molares infcriores. — El pm2 es sencillo y consta de una sola cuspide central y dos crestas oblicuas posteriores, las cuales con el desgaste van despareciendo, el tamano del diente es como la mitad del premolar siguiente, el cual ya presenta \anas coniplicaciones en sii estructura. La cara externa esta dividida en dos lobnlos por una escotadura poco profunda, el 161:)ulo posterior es aproximadamente un tercio del lobulo anterior. La cara lingual presenta una entrada en forma de U que separa de cara oclusal en dos lobulos, el anterior es muy pequeno y esta a su vez dividio en dos pequeiios lobulos los cuales con el desgaste se \"an uniendo hasta verse en los animales muy viejos solo una pequeiia entrants. El lobulo posterior, esta a su vez dividido por dos angulos entrantes muy profundos. La combinacion de estos dos angidos y el angulo externo, dan a la parte posterior del premolar forma de E con sus tres salientes hacia el lado lingual. El pm4, es ya muy parecido a los molares, esta constituido por dos lobulos, el posterior es mas pequefio que el anterior. Cada lobulo tiene dos crestas longitudinales, la lingual es casi recta; en cambio, la externa es en forma de V o de U segun el desgaste. En el ejemplar con poco desgaste solamente en la parte anterior de las crestas, la dentina se une; en cambio, en todos los otros la dentina se encuentra rodeada de esmalte; conforme el desgaste se continua, las crestas se van uniendo hasta formar ima sola placa con dos islas ovales de dentina, sitiiada mas o menos en el centro de los lobulos. En la cara externa entre los dos lobulos y en la base de la cara, existe un pequefio esHlo. Los molares 1 y 2 son iguales al premolar 4, pero el segundo lobulo tiende a ser mas grande, hasta alcanzar un tamaiio igual al primer lobulo en el tercer molar. EI ml presenta mayor desgaste que m2. Los estilos entre los lobulos estan mejor desarrollados que en pm4. El m3 presenta tres loliidos, los dos primeros mas o menos del mismo tamaiio y el tercero muy reducido. La parte anterior de las crestas del primer lobulo presentan la dentina continua, asi como la parte posterior interna del primer lobulo y la parte anterior de la cresta externa. El borde posterior interno de la cresta lingual del segundo lobulo y la parte anterior de la cresta lingual del tercer lobulo, tambien se continua, asi como las partes, posteriores de las crestas del tercer lobulo. Conforme avanza el desgaste, la dentina se va uniendo, sin embargo la parte posterior de la cresta lingual del lobulo primario no se une con los del segundo lobulo. En la cara interna tanto de los dos ultimos premolares como de los tres molares, hay unas pequeiias crestas que van de la parte mas alta de la corona a la base de la misma. Dientes stiperiores. — Los tres premolares estan formados por un solo lobulo, en cambio los molares estan formados por dos. El PM2 es el mas largo de los premolares. La cara labial esta dividida por un angulo entrante muy cerrado, situado en el primer quinto anterior del diente, despues tiene otra entrante mas abierta, en la base de la cual no existe ningi'm estilo. La cara oclusal se encuentra dividida en la mitad por una isla de esmalte que se extiende longi- tudinalmente, con entrantes y salientes irregulares. La cara lingual tambien tiene una entrante muy tenue, situada en el primer tercio anterior. 106 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. El PM3 es mas corto que el PM2, y su estnictura mas sencilla, consta de dos crestas con dentina enmedio, la laliial es recta y la lingual en forma de U. La parte anterior y la posterior de las crestas, se continuan. En la cara interna de la cresta lingual existen dos proyecciones hacia la cara interna de la cresta labial, sin llegar a unirse con ella. En la cara externa existen tres hordes bien marcados que van de la parte mas alta del molar a la base de la corona, en donde se juntan formando un borde horizontal en la base. Las crestas hajan de los extremos anterior y posterior de la corona y de la parte media de la misma. El PM4 es igual al anterior, pero ligeramente mas corto. Los tres molares son semejantes entre si y estan formados de dos lohulos, cada uno de igual magnitud y separados por ima entrante lingual en cuya base, en algunos ejemplares existe un estilo mas o menos bien desarrollado. Las crestas lahiales de los dos lohulos de cada molar se continuan entre si, lo mismo que con la parte anterior y posterior de las crestas lahiales, no asi los hordes posterior interne de las crestas linguales del primer y segundo lohulo respectivamente, los cuales estan separados entre si y de la cresta labial. En la cara externa de los molares existen cinco crestas bien marcadas que hajan de la parte alta de la corona a la base de la misma, en donde se unen. Las crestas se encuentran en la parte anterior del molar, otra en la posterior, ima en donde se unen los dos lohulos y dos mas en la parte media de cada 16]:)ulo. Entre cresta y cresta existe una depresion en forma de V 6 de U con la parte mas profunda hacia la base. Descripcion de las Astas De las astas de Odocoileus halli solo se recohraron cinco fragmentos, de los cuales dos estan muy destruidos y son muy pequenos para poder sacar alguna conclusion, de los otros tres, el mejor de ellos es el no. 1137 D.P., y forma parte de un craneo fragmentado de donde se recohraron los occipitales, region basal y fragmentos de los frontales con una parte de asta de 15 cm de longitud y la region basal de otra asta unida al frontal. El corte transversal (Fig. 6) de la base del asta de mayor tamano es ligeramente o\alado, con el diametro mayor transversal de 37.3 y el anteroposterior de 29.5. El corte del asta por arriha de la primera punta es mas circular, con el diametro transversal de 35.84 y el anteroposterior de 33.5. Toda la superficie del asta es rugosa; falta el anillo basal por lo que no podemos decir que forma y tamaiio pudo haher tenido. La superficie anterior del asta se abre aproximadamente a 165° con respecto a la superficie del frontal (Fig. 6). Otro fragmento de asta forma parte de una region frontal (1095 DP) con la base de ambas astas, las cuales se elevan en angulo de mas o menos 170° con respecto a la superficie del frontal. El corte transversal de la misma es de forma circular en sus caras anteriores y laterales pero completamente plana en la cara posterior (Fig. 6). Los diametros transversal y anteroposterior son respectiva- mente de 31.8 y 22.8. Por ultimo, existe un fragmento de asta (1085 DP) (lue consta de unos 18 cm de la rama principal con la region basal de una punta. El corte trans- versal de la rama principal antes de la punta ( Fig. 6 ) es ovalado, su diametro mayor es de 37.3, en cambio el anteroposterior es de 24.0. El corte despues de la punta conserva la misma forma o\a]ada aunque ya no tan marcada, prin- cipalmente porque presenta un abnltamiento anterointerno; el diametro trans- \ersal es de 26.5 y anteroposterior de 18.1 Alvarez — Pleistocene Fossils from Mexico 107 1137 DP pos 1095 D F'iG. 6. Difeientes fragmentos de asta de O. halli con cortes transversales de los misinos. 108 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Comparacion De todas las especies conocidas, tanto fosiles como vivlentes Odocoileus halli difiere por su mayor tamaiio, que es casi igual al de un pequeno Cervus. La unica especie que se le parece en tamano es Odocoileus brachyodontus Oelrich, 1953, pero difiere en que las crestas anterointerna y posterointerna estan unidas a la cresta transversal, en cambio en O. brachyodontus dichas crestas se encuentran separadas. Ademas, existe diferencia en epocas, ) a que O. brachy- odontus es del Pliocene y O. halli es del fin del Pleistocene. Notas Desde el momento en que el material de Tlapacoya fue \isto por el Dr. Clayton E. Ray de la Smithsonian Institution, me sugirio la idea de que pudiera corresponder nuestro material a Sangamona fugitiva, sin embargo al examinar CUADRO 1. MeDIDAS MANDIBULARES Y de LOS DIEXTES MAXILARES DE Odocoileus halli. Medidas No. No. No. No. No. No. No. mandibulares 1001 1002 1082 1083 1116 1119 1177 pm2 largo anclio pm3 largo anclio pm4 largo 17.9 ancho 12.7 ml largo 18.4 ancho 13.8 m2 largo 20.4 ancho 14.5 m3 largo 27.8 ancho 13.2 longitud alveolar 115.3 minima altura de la rama mand. 21.9 Altura rama bajo ml-2 43.6 9.8 10.0 10.6 11.8 7.0 6.9 6.8 7.0 16.3 15.7 15.9 15.6 10.1 10.9 10.0 9.8 18.2 17.6 16.3 17.8 17.8 16.7 12.6 12.7 12.4 12.5 12.6 11.3 19.4 16.3 16.5 17.1 15.5 17.8 14.0 12.9 12.3 12.9 11.5 13.2 20.7 20.5 20.4 19.7 20.4 21.0 14.4 14.0 14.7 13.7 13.4 15.1 28.0 27.0 30.0 25.9 24.6 13.2 14.4 13.7 13.2 13.9 115.2 105.2 104.5 115.0 111.2 20.2 20.4 18.5 20.8 44.5 39.8 39.0 38.4 38.1 Medidas de los No. No. No. No. No. dientes ma.xilares 1060 1092 1117 1145 1180 Suellos PM2 largo ._-.. ...... . ._.... 16.2 18.3 17.7 ancho ..... ...... . . 12.9 15.9 15.5 PM3 largo 16.0 ...... . 16.4 14.9 16.4 ancho 16.8 ...... ...._ . 14.3 16.9 19.9 PM4 largo 17.1 .... 17.2 . 15.4 . . ancho 17.5 ..- 18.7 ...... -.... Ml largo 22.4 19.7 22.4 __.... ...... . ...... ancho 18.3 20.9 20.9 19.5 ...... ..-.. ...... M2 largo 23.6 21.3 23.7 18.9 ...... . . ancho 20.5 23.0 22.7 21.2 ...... ...... . M3 largo 23.3 21.8 23.1 20.0 ..... ...... ...... ancho 18.2 21.4 20.6 21.1 ..... ...... ...... la descripcion de este genero y ver el molde del tipo que nos fue enviado por el Dr. Ray, encontramos que difiere mucho. De acuerdo con la descripcion original Sangamona difiere de los otros \'enados por carecer de las costillas en las caras externas de los lobulos de los molares. Dichas costillas estan bien marcadas en todos los molares de Tlapacoya; comparando el tipo de Sangamona con material de Odocoileus halli, encontramos que efectivamente las costillas Alvarez — Pleistocene Fossils from Mexico 109 son niiiy pnco marcadas y que la cara externa bajo el paracono y inetacono no presenta ninguna costilla, en cambio en este mismo liigar Odocoileus halli al igual que todas las otras especies de Odocoileus, presentan una costilla que desciende del metacono y paracono. Sau'^amona presenta tambien un estilo entre los dos lobulos internos, dicho estilo se presenta en la mayoria de los niolares de Odocoileus halli, asi como en otras especies que se pudieron ver, O. hcmionus y O. virginianus en ejemplares y O. salinae, O. cascensis, O. hrachijodontus en las figuras publicadas en su descripcion; otra forma que nos fue sugerida con posibilidad de ser igual a nuestro material fue Rangifer fiicki Schultz y Howard 1935. Al comparar el material de Tlapacoya con la figura publicada en la descripcion original de R. fricki, encontramos una semejanza muy estrecha en la forma de los dientes, asi como en sus dimenciones. Las unicas diferencias estriban en la longitud de algunos dientes: el segundo premolar inferior es ligeramente mas largo en R. fricki; en cambio, el tercer molar inferior es mas corto que en O. halli. Los molares superiores en general son mas largos y sobre todo mas anchos en O. haUi que en R. fiicki. A pesar de que la semejanza en forma es muy estrecha entre Odocoileus halli y R. fricki y que se asignan a diferentes generos, preferimos poner la especie halli dentro de el genero Odocoileus, porque como ya se indica, la estructura de los molares no difiere mas que en su tamano mayor, pero no en la estructura esencial de los dientes, creemos que mas bien Rangifcr fricki puede ser un forma de Odocoileus. Odocoileus halli ha sido nombrado en honor al Dr. E. Raymond Hall, como un estimonio de gratitud por todas las enseiianzas y atenciones que siempre he recibido de el. DiSCUSION Las excavaciones realizadas en el cerro de Tlapacoya, Mexico, durante el ano de 1966, nos dan por primera vez dentro del llamado Valle de Mexico, algunas fechas relacionadas con la fauna existente en dicha area. Los restos de animales fueron encontrados al realizar dos calas perpendiculares a la linea de la falda del cerro. Dentro de los muchos estratos que se identificaron, dos de ellos proporcionaron la mayoria de los huesos estudiados. El estrato mas antiguo en que se encontraron huesos, esta for- mado por cenizas volcanicas que en este punto se hallan en contacto con la roca basal y que tienen un espesor de un metro aproximada- mente. La edad de esta capa no se determine directamente, pero se infiere que sea mayor a los 24,000 anos, ya que los restos procedentes de una capa superior dieron la fecha antes indicada. La fauna de este estrato esta formada por numerosos restos de aves acuaticas y de mamiferos como Pappogeomijs sp., Stjlvilagus fioridanu.s, Neochoerus pinckneyi, Ltitra canadensis, Peromijscus maldonadoi, Odocoileus virginianus, y Mormoops megalophijlla. La asociacion de las aves acuaticas con mamiferos como Neo- choerus y Lutra, nos hacen pensar que hace 24,000 aiios la region 110 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. de Tlapacoya era miicho mas hiimeda y que debio de existir un lago, en cuyas margenes la vegetacion era exuberante. For los restos encontrados en esta capa, es difieil dicernir el tipo de clima existente en esa epoca con respecto a la temperatura, ya que la asociacion faunistica no es exclusiva de tierras calientes, aunque si se le encu- entra con preferencia en tal tipo de climas; ademas, la presencia de Mormoops, genero de murcielago que muy raramente se encuentra en climas frios y que vive mas bien en lugares calidos, nos inclina a pensar que el clima de esa epoca ero mas calido y humedo que el actual. El otro estrato en que fueron abundantes los restos oseos, se cncontro principalmente en la trinchera alfa y data de 22,000 aiios aproximadamente. Los restos encontrados en este sitio, fueron principalmente huesos de mamiferos grandes y formaban una aglomeracion muy marcada alrededor de unas grandes piedras que rodeaban un claro, en donde se cncontro carbon, asi como restos de utensilios humanos, ha sido interpretado como un hogar del hombre prehistorico. Aunque existen restos de pequeiios mamiferos, la gran mayoria corresponden a Odocoileus halli, especie de venado muy grande y que sin duda alguna proporciono al hombre buena cantidad de carne. Tambien se cncontro en la trinchera beta, pero no se ha- llaron restos de este animal en los mas antiguos de 24,000 afios, lo que nos hace suponer que dicho venado fue un inmigrante reciente, exterminado por la accion del hombre; en cambio Odocoileus vir- ginianus, cuya talla es mucho menor que O. halli, ya existia en el Valle de Mexico desde hace mas de 24,000 aiios y ha logrado resistir desde entonces el impacto de la accion humana, ya que este venado es uno de los pocos mamiferos de tamaiio regular que todavia se encuentran en los bosques de coniferas alrededor del Valle de Mexico. Summary The Departamento de Prehistoria of the Institute Nacional de Antropologia e Historia has been working for several years at Tlapacoya in the Valley of Mexico, looking for remains of prehistoric man. In 1966, two trenches were dug on the south side of Cerro Tlapacoya. Only two of the many strata found in the trenches fur- nished good quantities of bones. The oldest is a \'olcanic ash, which at this point is on bed rock. The exact age of this stratum is unknown, but the one above it was aged by C^^ analysis as 24,000 years old. Alvarez — Pleistocene Fossils from Mexico 111 Bones in this ash belong mainly to birds. Among the mammals it was possible to identify Pappogeoimjs sp., Sijlvilagus floridamis, Neoclioerus pinckneyi, Lutra canadensis, Peromysciis maldonadoi, Odocodeus virg,inianus, and Mormoops megaloplu/lla. The association of a(]uatic birds principally ( cormorants, herons, grebes, etc. ) and mammals like Lutra and Neoclioerus indicates that 24,000 years ago the region of Tlapacoya was more humid than now; probably the vegetation was more luxuriant than in Recent times. It is possible also that the average temperature was higher than it now is, as indicated by the presence of Mormoops, a bat which is abundant in warm regions. On the other hand, the rest of the mammalian fauna is found today in both warm and cool climates. Thus the fauna does not clearly indicate a particular climate. The other stratum with bones was found in the trench alpha and was dated as 22,000 years old. Bones from this level were of large mammals and it is believed that they were brought in by man, because they were grouped around several big stones and associated with charcoal. Most of the bones belong to a big deer, Odocodeus haUi, here described on the basis of its large size — larger than any other known Odocodeus. Comparison of O. halli with Sangamona reveals that they differ in the construction of the lingual ridges of the molars. Other remains found associated with O. liaUi were identified as follows: Urusus americanus, an almost complete skeleton; Si/Jvda- gus cunicularius, Pappogeomys sp., Neotoma mexicana, Microtus mexicanus, Canis sp., Procyon lotor and Odocodeus virginianus. All these mammals except the two first named still live today in the Valley of Mexico. LiTERATURA CiTADA Alvarez, T. 1966. Roedores fosiles del Pleistocene de Tequesquinahiia, Estado de Mexico, Mexico. Acta Zool. Mexicana, 8 (3): 1-16. Dalquest, W. W. 1961. Sylvilagiis cunicularius in the Pleistocene of Mexico. Jour. Mamm., 42: 408-409. Freudenberg, W. 1922. Die Saugetierfauna des Pliociins und Pospliocans von Mexiko. II Teil: Mastodonten und Elefanten. Geol u. Paleont. Abhand., 14: 103-176. C.oodlife, E., y M. Goodlife 1966. Un sitio Pleistocenico en Tlapacoya, Estado de Mexico. Bol. Inst. Nac. Antiopol. e Hist., 23: 30-32. 1969. Excavaciones en el cerio de Tlapacoya, Estado de Mexico, Sitio I. En prensa. 112 Misc. Publ. 51, Unr . Kansas Mus. Nat. Hist. Haynes, C. v., Jr. 1967. Muestras de C14, de Tlapacoya, Estado de Mexico. Bol. Inst. Nac. Antropol. e Hist., 29: 49-52. Hooper, E. T. 1957. Dental patterns in mice of the genus Peromijscus. Misc. Publ., Mus. Zool., Univ. Michigan, 99: 1-59, 24 figs. KXJRTEN, B. 1963. Fossil bears from Texas. Pearce Sellards Ser., Texas Mem. Mus., 1: 3-15, 6 figs. Merriam, C. H. 1895. Monographic revision of the pocket gophers. . . . N. Amer. Fauna, 8: 1-258, 19 pis., 71 figs. Stock, C. 1950. Bears from the Pleistocene cave of San Josecito, Nuevo Leon, Mexico. Jour. Wasliington Acad. Sci., 40: 317-321, 1 fig. BIOGEOGRAPHY OF SOUTHWESTERN BOREAL AND DESERT MAMMALS BY James S. Findley The southwestern part of the United States is a funnel-shaped region, consisting ecologically of an eastern and a western desert bisected by forested highlands through which only one or two lowland gaps permit the interchange of desert organisms. During later Pleistocene time the two deserts have been sundered and reunited, and the biota of the forested highlands has alternately spread and been fragmented into island-like refugia. It is my thesis that these historical events have been the principal agents in the remarkable diversification of mammals in the Southwest. This con- clusion is reached primarily on the basis of the observation of contemporary distribution and variation patterns and secondarily on the basis of deductions from known facts of southwestern climatic history. If the patterns of distribution and variation of mammals ap- peared non-correlated, one might conclude that a diversity of factors had shaped the patterns. If on the other hand certain pat- terns reappear commonly, one might suppose that only a few factors were involved, and it might be possible to identify these. It seems to me that the kinds of patterns displayed by southwestern mammals are indeed limited and often similar. The most frequent of these patterns are described in the following section. I have not attempted to be exhaustive, hoping that the selected examples are typical and point the way to the overall picture. The Boreal Pattern Boreal mammals are those that occupy montane coniferous forest zones where soil moisture is available and aridity is not an important limiting factor. The major features of the boreal pattern are: 1. Reduction of number of kinds of strictly lioreal species with decreasing latitude, even given seemingly comparable habitats. 2. Gradual replacement of northern boreal species with others at succes- sively lower latitudes. 3. Altitudinal zonation of northern and southern boreal species in areas of sympatry. 4. Increase in lower altitudinal limits of northern kinds at successively more southerly latitudes. (113) 114 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist, 106 Fig. 1. Geographic distribution of three species of Eiitamias: black, E. mini- mus; blotched pattern, E. dorsalis; stipple, E. quadrivittatus group. N Fig. 2. Altitudinal relationships of three species of Eiiiamias on southwestern mountain ranges: black, E. ininimiis; stipple, £. quadrivittatus group; blotched pattern, E. dorsalis; A, Animas Mountains; B, Black Range; W, White Moun- tains; J, Jemez Mountains. FiNDLEY — Southwestern Mammals 115 Selected examples ol southwestern boreal mammals displaying \'arious aspects of this pattern follow. Chipmunks of the Genus Eutomios Figures 1 and 2 show geographic and ecologic distribution of chipmunks in a part of the Southwest. Using the White Mountains of Arizona as a focal point for discussion, it can be seen that in the higher parts of this range the least chipmunk, Eutamias minimus, occurs in a rich, mesic, mixed coniferous forest along with the gray-necked chipmunk, E. cinereicollis, which is found to the lower limit of the ponderosa forest and there overlaps, and is replaced by, the cliff chipmunk, E. dorsaJis. The latter may, under suitable circumstances, occur nearly to sea level in the Sonoran desert. Eutamias dorsalis is widespread around the margins of the Sonoran desert, occurring in chaparral, encinal, pinyon-juniper woodland, and similar xeric habitats. However in the absence of other chip- munks, this species may occur in pine or mixed coniferous forest. The gray-necked chipmunk, together with its close relatives and Fig. 3. Geographic distribution of two species of Microtiis: black, M. nionianus; blotched pattern, M. mexicanus. 116 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. ; long Jackson Hole _.n VtYYYt ////////. •.•,:.•.♦.•.•.•.•.•.•. pen n ' ' M J emez I / lUi .iiiiiiiiiiiiiiii Y YYY V\/ -•,• • • • • • • •• •• ••- •.• •••• •• • •• • •• ff* •• •• • ••••• • • ' • • • I mon tonus White iiiiiiiiiiiii nnex iconus M ogol lo n > uYjYtn Fig. 4. Diagram of habitat relationships of four species of Microtus on three southwestern mountain ranges and in Jackson Hole, Wyoming. ecological vicariants, E. qiiadrivittatus, E. canipes, and £. hulleri, is widespread in mixed coniferous and ponderosa forest. In the absence of dorsalis, the species qiiadrivittatus and canipes occur down to the lower edge of the woodland, and, in places, even into FiNDLEY — Southwestern Mammals 117 the grassland. Eutamias minimus, in the Southwest, is limited to some of the most mesic ranges, but farther north occurs over wide continuous areas, even into the sage-grassland in Wyoming and adjacent states. That the least chipmunk is well adapted to boreal conditions is suggested by its extensive postglacial spread across the Canadian coniferous forest. Voles of the Genus Microtus Figures 3 and 4 depict geographic and ecologic distribution of several species of Microtus in the Southwest. Again using the White Mountains as a focal point, we find there the northern species, M. montamis, living in the most mesic microtine habitat — grass- sedge meadows around streams and ponds. In drier grasslands at the same altitude, and down to the lower edge of ponderosa forest occurs M. mexicanus. The montane and Mexican voles seem to occupy somewhat analogous positions to the least and gray-necked chipmunks, respectively, but there is no microtine analog to the cliff chipmunk. If we look below the pine forest in the Southwest for a grazer that is a grass-tunnel dweller, we find various species of the cricetine genus Sigmodon, an animal much more tolerant of xeric conditions than any Microtus. Aside from its drought-tolerant quali- ties, Sigmodon is so Microtus-\ike in reduction of countershading, reduction of appendages, burrowing and tunnel-dwelling propensi- ties, diurnal activity, grazing habit, and ability to respond to grass growth with population irruptions, that it might be thought of a "microtoid" cricetine. The species M. longicaudus is not primarily grass-dwelling, but rather a species of the forest edge, and thus does not enter directly into competition with the other two Microtus, nor is it closely related to them, usually being placed in another sub- genus. Thus its distribution in the Southwest is not directly related to the history of the other two species. On those ranges where the montane vole is not found, the Mexican vole occupies the most mesic habitats as well as more xeric areas, and I earlier ( Findley and Jones, 1962) postulated a competitive relationship between the two species, mexicanus invading those places in post-pluvial times where montanus had become extinct. Rabbits of the Genus Sylvilogus Geographic and ecologic distribution of three species of Sylvi- lagus in the Southwest is shown in Figures 5 and 6. The higher elevations of the White Mountains are inhabited by S. rmttaUii. 118 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 5. Geographic distribution of three species of SlJlviIa^tls: black, S. niii- iallii; blotched, S. floridamis; wliite, S. auduhonii. More southerly and lower ranges are occupied by S. floridamis, which occurs so low as 2000 feet in Arizona ( Hoffmeister and Lee, 1963). In the woodlands, grasslands, and deserts at all lower eleva- tions in the Southwest occurs S. auduhonii. Farther north S. nuttalUi is more continuously distributed and often occurs at low elevations in the absence of the other two species. That S. floridamis is not, at first glance, a convincing analog of the Eutamias quadrivitatus group and Microtus mexicamis cannot be debated. Sijlvilagus flori- damis is widely distributed in the eastern United States and in Mexico, and attempting to derive the species by pluvial abandon- ment in the Southwest may seem to be in violation of the precepts of Occam's razor. However, the range of S. floridamis in the South- west is highly disjunct, and western populations are largely sep- arated from those to the east. The populations of the region, including those of Mexico, are quite variable, and it seems to me that the conspecificit)' of this widespread assemblage is far from obvious. There is at least a possibility that the montane, forest- FiNDLEY — Southwestern Mammals 119 SYLV ILAGUS Fig. 6. Diagram of altitiidinal relationships of tliree species of Stjlvilagus on selected mountain ranges in the Southwest. MYOTIS lucifugus »'..""/'■»« .V r I .V' ^an^vryumanensis .•;'".'.->^S3 vel ifer Desert Grass & woodland Boreal forest Fig. 7. Diagram of habitat relationships of six species of Mijoiis in the South- west. dwelling S. floridamis of the Southwest and the Sierra Madre Occi- dental is a derivative of the closely related S. miftallii. Serological 120 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 8. Distribution of bats of the Myotis evotis group: solid lines enclose range of M. evotis; blotched pattern, M. keenii; stipple, M. thijsanodes. and karyological studies are strongly indicated for this group of mammals. Bats of the Genus Myotis Three groups of three species each may be delineated among the Myotis of the Southwest. ( 1 ) The lucifugtis group, consisting of hicifiigus (including occtdttis), ytimanensis, and velifer, alike in having unkeeled calcars, large feet, relatively short ears, and rela- tively short broad rostra with relatively large molars, the paralophs, metalophs, and hypocones of which are well-developed. Usually these bats are found near sources of permanent water of relatively large size. (2) The evotis group, consisting of evotis, keenii (races apache and aurictihis), and thysanodes, alike in having long ears, relatively long, slender rostra, slightly keeled or non-keeled calcars, a tendency to have a fringed trailing edge to the uropatagium, and upper molars with reduced or absent lophs, and a reduced hypo- cone. (3) The volans group, consisting of volans, Jcihii (formerly FiNDLEY — Southwestern Mammals 121 Fig. 9. Distrilmtion of bats of the Myotis hicifti^iis group: solid lines enclose range of M. hicifiigus; blotched pattern, M. ijwnanensis; stipple, M. vclifer. subulatus), and califoniicus, alike in small size, medium ears, strongly keeled calcar, small feet, and hicifugiis-\ike molars. Sum- mer geographic and ecologic distribution of some of these species in the Southwest is shown in Figures 7 through 9. In each case, one member of a species group is definitely boreal, one is most com- mon at middle elevations in pine forests and woodlands, and one is a desert and grasslands species. The lucifugus group requrres special comment in this regard. Maternity colonies of M. lucifugus occultus and M. yumanensis occur at some rather low elevations as at Socorro, New Mexico, and Blythe, California. Here, however, the colonies are located near large permanent bodies of water, the Rio Grande and the Colorado River. In the postpluvial retreat of these water-loving species, it might be expected that they would persist in the few water-rich lowland habitats, especially the more arid-adapted yumanensis, which, of course, is much more common in south^\'estern lowlands than is lucifugus. 122 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. The Desert Patterns Desert mammals are those living in lowlands where aridity exerts a dominant limiting and molding force on the animals. Desert mam- mals in the region under consideration exist in an eastern ( Chihua- huan) center and a western (Sonoran) center, and frequently extend from one center to the other through the lowland gap ( the Deming Plain) extending across southwestern New Mexico and southeastern Arizona. Several patterns seem to recur among these mammals. 1. Widespread continuous distribution through both deserts with little striking geographic variation. Dipodomys merriami seems typical of this pattern. Teroiinathiis peniciUatus recently studied by Hoffmeister and Lee (1967) seems to show several concordant character shifts, one of which coincides with the Continental Divide. Other species include Notiosorex crawfordi, SijJvilogus auduhonii, Lepus californicus, Peromyscus eremicus, Omjchomys torridus, and Neotoma albigida. 2. As above but with one or more sharp character breaks, often in the area of the Continental Divide, or between southern and central Mexican Plateau populations. Unpublished results of a study by myself and Gerald L. Traut reveal that the desert bat PipistreUtis hesperus, while showing numerous local adaptations, is di\'isible into a large eastern and a small western population. Whereas in some areas size of this species is responsive to climate, this is not the explanation for the present distribution of the two populations. The two kinds contact, with a steep clinal change in size, along the Continental Dixide ( Fig. 10 ) . The widespread hispid cotton rat, Sigmodon hispidus, occurs in parts of the southwestern deserts where a cover of grass is available. While these animals extend across the Deming Plain, Mohlhenrich ( 1961 ) thought that they had entered this area recently, and Gen- naro ( 196S ) concurred as a result of his finding that cotton rats in the Deming Plain were not adaptively colored. Gennaro thought that these animals had entered the Deming Plain from both east and west. Recently Earl Zirnmermann (personal communication) has revealed that animals from southern Ai-izona ha\e a fundamen- tal chromosome number of 38, while those from Lubbock, Texas, to the east have a fundamental number of 52 to 54. It may well be that the two differently colored hispid cotton rats of the Deming Plain also differ karyologically, providing an important example of this pattern. FiNDLEY — Southwestern Mammals 123 Fig. 10. Size in PipistreUus Jicsperus leased on 10 size variables. The darker the circle the larger the bats from that area. Black areas are forested highlands. Fig. 11. Eastern limits of western desert species described in text. Black areas are forested highlands. 124 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 3. Largely confined to the Sonoran desert, barely extending to the Continental Divide area. Selected species are Choeromjcteris mexicana, Perognathus haileyi, Macrotus tvaterhousii, Spermophilus tereticaudus, Perognathus longimembris, Perognathus amplus, Dipo- domys deserti, and Peromyscus merriami. Eastern limits of selected species in this category are shown in Figure 11. 4. Largely confined to the Chihuahuan desert, barely extending into the Continental Divide area. Selected species are Spermophilus spilosoma, Perognathus merriami, Perognathus flavus, Perognathus hispidus, Dipodomys spectahilis, Dipodomys ordii, Onychomys leucogaster, ReitJirodontomys montanus, Peromyscus leucopus, and Neotoma micropus. Western limits of selected species from this category are shown in Figure 12. 5. Like 3 or 4 above, but with a close relative in the other desert. Determination of this situation depends upon sound knowl- edge of relationships, frequently not available. That the white-sided jackrabbits, Lepus caUotis and L. alleni, are closer to each other than to other species seems accepted by students of the group. Ranges of the two are basically Chihuahuan and Sonoran, re- spectively. The antelope squirrels, Ammospermophihis, show a similar pattern, more striking because of disjunction, and because the trans-Coloradan isolate, A. leucurus, has encircled the Chihua- huan desert from the north and thus closely approaches its Chi- huahuan relative (A. interpres). Perognathus intermedins and P. nelsoni seem to fit this pattern although here the Sonoran isolate, P. intermedins, has extended well into the Chihuahuan desert, whereas its Chihuahuan relative, P. nelsoni, seems to have been rather sedentary. Ranges of two of these species pairs are shown in Figure 13. Development of Patterns That major ages of cool, moist climates, recurring during the Pleistocene, caused depression and coalescence of montane forests in the Southwest seems established beyond reasonable doubt. This is the only easily acceptable explanation for the existence of south- western montane boreal islands. If more than one cycle of pluvial-interpluvial conditions affected the Southwest, and if montane highlands existed there to act as interpluvial refugia for boreal organisms, it is possible to hypothe- size a series of events that could have led to the present diversifica- tion of the southwestern boreal and sub-boreal mammalian fauna. FiNDLEY — Southwestern Mammals 125 Fig. 12. Western limits of eastern desert and grassland species described in text. Black areas are forested highlands. Fig. 13. Ranges of related pairs of species: solid lines, Lepiis aUeni (west) and L. callotis (east); dashed lines, Aminospermophilus hairi.sii (west) and A. inierpres (east). 126 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. A A A Fig. 14. Diagrams showing hypothetical sequence of events in development of zonation of lioreal mammals in the Southwest. See text for explanation. These hypothetical events are diagrammed in Figure 14, where the stippled pattern represents the distribution of a boreal mammalian taxon, moving northward and southward, as well as up and down mountain slopes, with Pleistocene climatic fluctuations. Figure 14A represents conditions during a pluvial time when boreal species A is continuously distributed in the Southwest. In figure 14B, inter- FiNDLEY — Southwestern Mammals 127 plux'ial climates have resulted in northw aid and upward \\'ithdrawal of species A with its isolation on a mountain range. Figure 14C represents a later time during the interpluvial when the montane isolate has differentiated, perhaps in response to the arid marginally boreal conditions in which it was trapped as well as through the vagaries of random genetic phenomena, and now is different from its northern relative and hence designated B, and shown with a different pattern. Figure 14D shows another pluvial time. Species A and B have both mo\'ed southward, B, by viitue of its adaptation to less boreal conditions, being commonest in lower and more southern areas. Note that A and B may coexist and hence are con- sidered to ha\e speciated. Figure 14E depicts another interpluvial. Species A and B have moved northward and upward. On the moun- tain both are now isolated, A, still more borealy adapted than B, occupying higher more mesic areas. A continuation of this cycle of exents might result in still more complex stratification of boreal mammals. Such a situation would result only if the taxon involved could adapt to the somewhat more arid conditions obtained on small boreal islands. Many boreal isolates would become extinct with each interplu\'ial, leaving no descendants. If the postulated series of extents ever took place, we might expect to find some cases of closely related, probably congeneric species occupying successive altitudinal zones, or at least local habitats differing in available moisture, on southwestern mountain ranges. With each expansion of the boreal environment during pluvial times, the highlands of the Deming Plain must have been largely unavailable to desert mammals with the result that Sonoran and Chihuahuan segments of the ranges of many species must have been separated from one another. Under these ciix-umstances, divergence of the two segments could ha\'e proceeded in response to differential selective pressures and random phenomena, with the following pos- sible results. ( 1 ) Elimination of one segment of the population. With postpluvial spread of desert organisms the surviving population reoccupies the entire desert area, as has Dipodomys merriami. (2) The two segments differentiate but do not attain reproductive isola- tion, hence secondary intergradation takes place when they reestab- lish contact, as seems to be the case with PipistreUtis liesperus. (3) Only one population survives, but fails to reoccupy the entire desert area, perhaps because it has become too dependent on low or high desert conditions. Examples might be Spermophihis tereti- 128 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. caiuJus and S. spilosoma. (4) The two populations attain repro- ducti\'e isolation. Perhaps there are no cases of this among mam- mals where the specific level of the populations is demonstrated by natural sympatry, though this may be an artifact of our imperfect knowledge of degrees of relationships between species. However, there seems little doubt that Lepus callotis and L. alleni are spe- cifically distinct, and many species pairs such as the two Omjchomys may be examples of this situation. Some patterns suggest that in immediate postpluvial times eastern grassland species spread westward across the Deming Plain into the grasslands of southern Arizona. Subsequent progressive aridity limited these grassland species to grassland zones between desert and encinal on many desert mountain ranges, thus resulting in doughnut shaped relict ranges for some species such as Dipo- domijs ordii in southern Arizona. Of course, such grassland species may have existed on both sides of the Continental Divide during pluvial times, since pluvial grasslands were evidently widespread in southern Arizona and in Sonora. It is evident that repeated dividing and reuniting of deserts could provide the mechanism for the proliferation of desert species. Summary So far back in the Pleistocene as the present physiography has existed in the Southwest, we may imagine an oscillating series of boreal expansions coupled with desert contractions, alternating with desert expansions coupled with boreal retreats. The former phases resulted in desert speciation, the latter in boreal speciation. It seems to me likely that the majority of distribution and variation patterns in the Southwest and indeed in all of western North America will be found to be largely shaped by these events. Literature Cited FiXDLEY, J. S., AND C. J. JONES 1962. Distribution and variation of voles of the genus Microtiis in New Mexico and adjacent areas. Jour. Mamm., 43:154-166, 5 figs., May 29. Genxaro, a. L. 1968. Color \ariation of the hispid cotton rat in New Mexico. Jour. Mamm., 49:317-318, May 20. HOFFMEISTER, D. F., AND M. R. LeE 1963. Taxonomic review of cottontails, Sylvilagus floridanus and Sylvilagus nuttalhi, in Arizona. Amer. Midland Nat., 70:138-148, 2 figs., July. 1967. Revision of the pocket mice, Perognathus penicillatus. Jour. Mamm., 48:361-380, 5 figs., August 21. MOHLHEXRICH, J. S. 1961. Distribution and ecology of the hispid and least cotton rats in New Mexico. Jour. Mamm., 42:13-24, 3 figs., February 20. HOLOTYPES OF RECENT MAMMALS IN THE MUSEUxM OF NATURAL HISTORY, THE UNIVERSITY OF KANSAS BY J. Knox Jones, Jr., and Hugh H. GExNOWays Various museums in recent years have published Hsts of type specimens housed' in their collections. Such lists provide a useful point of reference for systematists and, for that reason, have been encouraged by the International Council of Museums. In 1968, that organization issued "A preliminary list of catalogues of type speci- mens in zoology and palaeontology," compiled by A. W. F. Banfield, and a revised list is planned for 1971. This catalogue of holotypes of mammals in The University of Kansas Museum of Natural History is particularly appropriate for the present volume, because Professor E. Raymond Hall was directly responsible for the descriptions of 20 taxa here listed, and was instrumental in arranging support for field work that resulted in the collection of many others. The first type specimen of a mammal designated from the col- lections at Kansas was the holotype of ''Reitliroclontomys dijchei,' described by J. A. Allen (1895:120). This specimen, originally KU (old series) 5232, was renumbered as 10127/8431 in the mammal collection of the American Museum of Natural History, where it now is housed. Similarly, the holotype of "Mimoii cozwnelae," named by E. A. Goldman (1914:75), previously was in the collec- tion at Kansas (original number, if any, unknown), but was pre- sented to the U. S. National Museum, where it now is deposited as USNM 203191. Ninety-nine holotypes and one allotype were among the nearly 120,000 specimens of Recent mammals housed in the Museum of Natural History as of December 31, 1968. These include two insecti- vores, 17 bats, five lagomorphs, 73 rodents, and two carnivores. Four of the holotypes — Nijcteris vinsoni Dalquest, Scotophiliis al- vensJebeni Dalquest, Eumops perotis renatae Pirlot, and Ochotona princeps howelli Borell — were donated to the museum subsequent to the original description. Additionally, two holotypes of the rodent genus Ochrotomijs are designated in this volume. (129) 130 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. List of Holotypes In the following list, holotypes are arranged under the name by which they were originally described. Condition of specimens and current nomenclatorial status of taxa are mentioned where appropri- ate. Under each ordinal name, genera are listed phylogenetically (those from North America after Hall and Kelson, 1959), whereas species and subspecies are arranged alphabetically. Insectr'Ora Cryptotis euryrhynchis Genoways and Choate, Proc. Biol. Soc. Washington, 80:203, December 1, 1967. Holotype. — Adult male, skin and skull, KU 107143, from Volcan de Fuego (also called Volcan de Colima), 9800 ft., Jalisco; obtained July 10, 1966, by Percy L. Clifton, original number 11059. Remarks. — Braincase of skull smashed and coronoid process of left ramus broken. Scalopus montanus Baker, Univ. Kansas Publ., Mus Nat. Hist., 5:19, Feb- ruary 28, 1951. Holotype. — Adult male, skin, skull, and body skeleton, KU 35668, from Club Sierra del Carmen, 2 mi. N and 6 mi. W Piedra Blanca, Coahuila; obtained April 7, 1950, by J. R. Alcorn, original number 11093. Chiroptera Nycteris vinsoni Dalquest, Jour. Mamm., 46:256, May 20, 1965. Holotype. — Adult female, skin and skull, KU 105221, from S bank Save River, 212 km. SSW Beira, Mozambique; obtained October 8, 1963, by Walter W. Dalquest, original number 18739. Leptonycteris nivalis longala Stains, Univ. Kansas Publ., Mus. Nat. Hist., 9:355, January 21, 1957. Holotype.— Aduh female, skin and skull, KU 33087, from 12 mi. S and 2 mi. E Arteaga, 7500 ft., Coahuila; obtained July 11, 1949, by W. K. Clark, original number 787. Remarks. — Regarded as a synonym of Leptonycteris nivalis (Saussure, 1860) by Davis and Carter (1962:194). Stumira ludovici occidentalis Jones and Phillips, Univ. Kansas Publ., Mus. Nat. Hist., 14:477, March 2, 1964. Holotype.— Adult female, skin and skull, KU 92798, from Plumosas, 2500 ft., Sinaloa; obtained August 31, 1962, by Percy L. Clifton, original number 2939. Remarks. — Canine and first premolar of right ramus missing. Natalus mexicanus saturatus Dalquest and Hall, Proc. Biol. Soc. Washing- ton, 62:153, August 23, 1949. Holotype. — Adult male, skin and skull, KU 23815, from 3 km. E San Andreas [=Andres] Tuxtla, 1000 ft., Veracruz; obtained January 10, 1948, by Walter W. Dalquest, original number 8621. Remarks. — Hole in the mid-ventral region of skin; left upper canine missing. Arranged as Natalus .stramineus saturatus by Goodwin (1959:7). Jones and Genoways — Holotypes of Mammals 131 Regarded as a synonym of Nataltis .stiaininctis nicxicanus Miller, 1902, by Handley (1966:770). Myotis argentatus Dalquest and Hall, Univ. Kansas Publ., Mus. Nat. Hist., 1:239, December 10, 1947. Holotype.— Adult male, skin and skull, KU 19228, from 14 km. SW Coatzocoalcos, 100 ft., Veracruz; obtained February 2, 1947, by Walter W. Dalquest, original number 7052. Myotis elegans Hall, Univ. Kansas Publ., Mus. Nat. Hist., 14:163, May 21, 1962. HoIoUjpe.—Aduh female, skin and skull, KU 88398, from 12)^ mi. N Tihuatlan, 300 ft., Veracruz; obtained September 24, 1961, by Percy L. Clifton, original number 985. Remarks. — Right upper incisors and canine, left upper canine and second small premolar, and lower left first molar missing, both zygomatic arches broken, and both auditory bullae separated from skull. Myotis evotis auriculus Baker and Stains, Univ. Kansas Publ., Mus. Nat. Hist., 9:83, December 10, 1955. Holottjpe. — Adult female, skin and skull, KU 55110, from 10 mi. W and 2 mi. S Piedra, 1200 ft., Sierra de Tamaulipas, Tamaulipas; obtained June 9, 1953, by Gerd H. Heinrich, original number 7061. Remarks. — Skin with hole along ventral slit. Arranged as Myotis keenii auriculus by Findley (1960:18). Arranged as Myotis auriculus auriculus by Genoways and Jones (1969:10). Myotis nigricans dalquesti Hall and Alvarez, Univ. Kansas Publ., Mus. Nat. Hist., 14:71, December 29, 1961. Holotype. — Adult male, skin and skull, KU 23839, from 3 km. E San Andres Tuxtla, 1000 ft., Veracruz; obtained January 5, 1948, by Walter W. Dalquest, original number 8444. Remarks. — Skin with hole along right side; right zygomatic arch broken. Myotis planiceps Baker, Proc. Biol. Soc. Washington, 68:165, December 31, 1955. Holotype. — Adult male, skin and skull, KU 48242, from 7 mi. S and 4 mi. E Bella Union, 7200 ft., Coahuila; obtained June 24, 1952, by Albert A. Alcorn, original number 920. Remarks. — Parietals and major portion of frontals missing. Myotis thysanodes pahasapensis Jones and Genoways, Jour. Mamm., 48:231, May 20, 1967. Holotype. — Adult male, skin and skull, KU 100704, from 6 mi. N New- castle, 6000 ft., Weston Co., Wyoming; obtained July 2, 1965, by Ronald W. Turner, original number 156. Myotis velifer brevis Vaughan, Univ. Kansas Publ., Mus. Nat. Hist., 7:509, July 23, 1954. Holotype. — Adult male, skin and skull, KU 22631, from Madera Canyon, 5000 ft., Santa Rita Mountains, Pima Co., Arizona; obtained March 12, 1948, by J. R. Alcorn, original number 5571. Pipistrellus subflavus clarus Baker, Univ. Kansas Publ., Mus. Nat. Hist., 7:585, November 15, 1954. Holotype. — Adult female, skin and skull, KU 48270, from 2 mi. W Jimenez, 132 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. 850 ft., Coahuila; obtained June 19, 19.52, l>y Rollin H. Baker, original number 2062. Scotophilus alvenslebeni Dalquest, Jour. Mamm., 46:258, May 20, 1965. Holotijpe. — Adult male, skin and skull, KU 105222, from S bank Save River, 212 km. SSW Beira, Mozambique; obtained October 9, 1963, by Walter W. Dalquest, original number 18767. Remarks. — Regarded as synonym of Scotophilus gigas Dobson, 1875, by Dalquest (1966:134). Lasiurus intermedius insularis Hall and Jones, Univ. Kansas Publ., Mus. Nat. Hist., 14:85, December 29, 1961. Holotijpe. — Adult female, specimen stored in spirits with skull removed, KU 81666, from Cienfuegos, Las Villas Prov., Cuba; obtained January 3, 1948, by D. Gonzales Muiioz, original number, if any, unknown. Remarks. — Skull missing left auditory bulla. Antrozous bunkeri Hibbard, Jour. Mamm., 15:227, August 10, 1934. Holotype. — Adult female, skin and skull, KU 9302, from 7 mi. S [actually 4/2 mi. S, ^4 mi. E] Sun City, Barber Co., Kansas; obtained September 2, 1933, by Hobart Smith and Claude W. Hibbard, original number 538 (Hibbard). Remarks. — Arranged as Aiitrozous pallidits hunkeri by Krutzsch and Vaughan 1955:97, 99) and by Morse and Class (1960:15). A corrected state- ment of the type locality was published by Jones et al. ( 1967:25). Molossops greenhalli mexicanus Jones and Genoways, Proc. Biol. Soc. Wash- ington, 80:207, December 1, 1967. Holotype.— Adult male, skin and skull, KU 108609, from VA mi. SE Teco- mate, 1500 ft., Jalisco; obtained December 7, 1966, by Percy L. Clifton, original number 11998. Eumops perotis renatae Pirlot, Le Naturaliste Canadian, 92:5, January, 1965. Holotype. — Adult female, specimen stored in spirits with skull removed, KU 115920, from Cumana, Sucre, Venezuela; obtained on unknown date by R. P. C. Prieto, original niunber, if any, unknown. Remarks. — Skull cracked across interorbital region and longitudinally along the palate; part of right maxillary, part of fourth upper premolar, and part of left parietal missing. This specimen, which was originally deposited in the Collegio San Jose in Cumana, Venezuela, was obtained for the Museum of Natural History 1)y James D. Smith from R. P. C. Prieto. Smith entered the specimen in his field catalogue as number 2852. Pirlot (1968:90) claimed specific rank for renatae. Lagomorpha Ochotona princeps howelli Borell, Jour. Mamm., 12:306, August 24, 1931. Holotype. — Adult male, skin and skull, KU 45705 (originally number 8744 in collection of Ralph Ellis), from summit of Smith Mountain (near head Bear Creek, S end of Seven Devils Mountains), 7500 ft., Adams Co., Idaho; obtained July 16, 1930, by Raymond M. Gilmore, original number 1325. Ochotona princeps obscura Long, Univ. Kansas Publ., Mus. Nat. Hist., 14: .538, July 6, 1965. Holotype. — Subadult male, skin and skull, KU 32918, from Medicine Wheel Ranch, 9000 ft., 28 mi. E Lo\ell, Big Horn Co., Wyoming; obtained July 7, 1949, by J. W. Twente, original number 232. Jones and Genoways — Holotypes of Mammals 133 Remarks. — Braincase cracked but intact, tips of nasals and posterior exten- sion ot the left zygomatic arch missing. Sylvilagus floridanus nelsoni Baker, Univ. Kansas Publ., Mus. Nat. Hist., 7:611, April 8, 1955. Holotype. — Adult female, skin and skull, KU 57771, from 22 mi. S and 5 mi. W Ocampo, 5925 ft., Coahuila; obtained April 4, 1952, by Rollin H. Baker, original number 2571. Remarks. — Posterior portion of right supraorbital process missing. Regarded as synonym of Sylvilagus floridanus robusttis (Bailey, 1905) by Raun (1965: 521). Lepus americanus seclusus Baker and Hankins, Proc. Biol. Soc. Washing- ton, 63:63, May 25, 1950. Holotype. — Adult male, skin and skull, KU 20897, from 12 mi. E and 2 mi. N Shell, 7900 ft.. Bighorn Mts., Big Horn Co., Wyoming; obtained July 8, 1947, by Gilbert Winemiller, original number 22 of Joao Moojen. Remarks. — Baker (1959:145) believed seclusus to be preoccupied by Lepus timid us seclu.sus Degerbpl, 1940, and therefore proposed the replacement name Lepus americanus setzeri for this subspecies. Long (1965a:548: 1965b: 125- 126) considered the name Lepus americanus seclusus Baker and Hankins not to be preoccupied by Lepus timidus seclusus Degerb0l because the latter name pertains to a "variety" or "forma," which ha\e no standing under the Code; therefore he regarded Lepus americanus .setzeri Baker as a junior synonym of L. a. seclusus. Lepus califomicus curti Hall, Univ. Kansas Publ., Mus. Nat. Hist, 5:42, October 1, 1951. Holotype. — Adult female, skin and skull, KU 35470, from an island, 88 mi. S and 10 mi. W Matamoros, Tamaulipas; obtained March 19, 1950, by E. R. Hall, original number 6783. RODENTIA Eutamias minimus silvaticus White, Univ. Kansas Publ., Mus. Nat. Hist., 5:261, April 10, 1952. Holotype. — Adult female, skin and skull, KU 20050, from 3 mi. NW Sun- dance, 5900 ft.. Crook Co., Wyoming; obtained July 4, 1947, by H. W. Setzer, original mmiber 1692. Eutamias umbrinus fremonti White, Univ. Kansas Publ., Mus. Nat. Hist., 5:575, December 1, 1953. Holotype. — Adult male, skin, skull, and prepared baculum, KU 41790, from 31 mi. N Pinedale, 8025 ft., Sublette Co., Wyoming; obtained July 8, 1951, by Rollin H. Baker, original number 1596. Eutamius umbrinus monlanus White, Univ. Kansas Publ., Mus. Nat. Hist., 5:576, December 1, 1953. Holotype. — Adult male, skin, skull, and prepared baculum, KU 20105, from )2 mi. E and 3 mi. S Ward, 9400 ft., Boulder Co., Colorado; obtained August 1, 1947, by E. L. Cockrum, original number 721. Marmota monax bunkeri Black, Jour. Mamm., 16:319, November 15, 1935. Holotype.— Aduh female, skin and skull, KU 3089, from 7 mi. SW Law- rence, Douglas Co., Kansas; obtained March 8, 1920, by Fred Hastie, original number, if any, unknown. 134 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Spermophilus spilosoma oricolus Alvarez, Univ. Kansas Publ., Mus. Nat. Hist., 14:123, March 7, 1962. Holotijpe. — Adult female, skin and skull, KU 55497, from 1 mi. E La Pesca, Tamaulipas; obtained March 27, 1953, by Gerd H. Heinrich, original number 6933. Thomoniys bottae angustidens Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:508, June 1, 1953. Holotijpe. — Adult male, skin and skull, KU 48481, from Sierra del Pino, 6 mi. N and 6 mi. W Acebuches, Coahuila; obtained July 3, 1952, by Rollin H. Baker, original number 2141. Remarks. — Hall and Kelson (1959:416) arranged tliis and other subspecies of Thomomys hottae as races of Thomomijs umhrimis; however, several recent authors (Anderson, 1966:189; Dunnigan, 1967:144; Patton and Dingman, 1968:2) have shown the t\\'o species to be distinct. Thomomys bottae caneloensis Lange, Proc. Biol. Soc. Washington, 72:131, Noveml^er 4, 1959. Holotijpe. — Adult male, skin and skull, KU 51788, from Huachuca Moun- tains, west foothills, Canelo, 10 mi. S Elgin, 5100 ft., Santa Cruz Co., Arizona; obtained November 30, 1952, by Gerd H. Heinrich, original number 5551. Allotype.— Adult female, skin and skull, KU 51786; obtained November 29, 1952, by Gerd H. Heinrich, original number 5549. Thomomys bottae humulis Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:503, June 1, 19.53. Holotype.—Adu\t male, skin and skull, KU 35746, from 3 mi. W Hda. [Hacienda] San Miguel, 2200 ft., Coahuila; obtained April 4, 1950, l^y J. R. Alcorn, original number 11039. Thomomys bottae retractus Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:507, June 1, 1953. Holotijpe.— Aduh male, skin and skull, KU 44826, from Fortin, 3300 ft., 33 mi. N and 1 mi. E San Geronimo, Coahuila; obtained March 29, 1952, by Rollin H. Baker, original number 1971. Thomomys bottae rubidus Youngman, Univ. Kansas Publ., Mus. Nat. Hist., 9:.376, February 21, 19.58. Holotijpe.- Aduh female, skin and skidl, KU 72954, from 2 9/10 mi. E Caiion City, 5344 ft., Fremont Co., Colorado; obtained March 17, 1957, by Richard S. Miller and Phillip M. Yougman, original number 253 (Youngman). Thomomys bottae villai Baker, Uni\ . Kansas Publ., Mus. Nat. Hist., 5:505, June 1, 1953. Holotype.— Adult female, skin and skull, KU 44816, from 7 mi. S and 2 mi. E Boquilias, 1800 ft., Coahuila; obtained March 1, 1952, by Rollin H. Baker, original number 1816. Thomomys talpoides attenuatus Hall and Montague, Univ. Kansas Publ., Mus. Nat. Hist., 5:29, February 28, 1951. Holotijpe.— Adult male, skin and skull, KU 15095, from 3)2 mi. W Horse Creek Post Office, 7000 ft., Laramie Co., Wyoming; obtained July 16, 1945, by Henry W. Setzer, original number 629. Thomomys talpoides meritus Hall, Univ. Kansas Pul)l., Mus. Nat. Hist., 5:221, December 15, 1951. Jones and Genoways — Holotypes of Mammals 135 Holottjpe. — Adult male, skin and skull, KU 25628, from 8 mi. N and 19/2 mi. E Savery, 8800 ft., Carbon Co., Wyoming; obtained July 19, 1948, by George M. Newton, original number 4. Thomomys talpoides rostralis Hall and Montague, Univ. Kansas Publ., Mus. Nat. Hist., 5:27, February 28, 1951. Holottjpe. — Adult female, skin and skull, KU 17096, from 1 mi. E Laramie, 7164 ft., Albany Co., Wyoming; obtained August 26, 1946, by C. Howard Westman, original number 320. Remarks. — The date on which the holotype was captured was incorrectly given as July 16, 1945, in the original description. Thomomys umbrinus varus Hall and Long, Proc. Biol. Soc. Washington, 73:35, August 10, 1960. Holotype. — Adult male, skin and sk-ull, KU 75271, from 1 mi. S El Dorado, Sinaloa; obtained November 14, 1957, by William L. Cutter, original number 1452. Remarks. — Left upper premolar missing. Regarded as a synonym of Thomorinjs bottae sinaloae Merriam, 1901, by Dunnigan (1967:149). Geomys bursarius industrius Villa-R. and Hall, Univ. Kansas Publ., Mus. Nat. Hist., 1:226, November 29, 1947. Holotype. — Adult male, skin and skull, KU 14083, from Ui mi. N Fowler, Meade Co., Kansas; obtained December 30, 1941, by H. H. Hildebrand, orig- inal number 16. Remarks. — Exposed portion of right upper premolar missing. Heterogeomys hispidus latirostris Hall and Alvarez, An. Escuela Nac. Cien. Biol., 10:121, December 20, 1961. Holotype. — Adult female, skin and skull, KU 82968, from Hacienda Tamia- hua, Cabo Rojo, Veracruz; obtained April 2, 1960, by M. R. Lee, original number 1822. Remarks. — Catalogue number of the holotype was incorrectly listed in the original description as 83968. Arranged as Orthogeomys hispidus latirostris by Russell (1968a: 531). Pappogeomys alcomi Russell, Univ. Kansas Publ., Mus. Nat. Hist., 9:359, January 21, 1957. Holotype. — Adult female, skin and skull, KU 39806, from 4 mi. W Maza- mitla, 6600 ft., Jalisco; obtained October 18, 1950, by J. R. Alcorn, original number 12835. Pappogeomys bulleri infuscus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:610, August 5, 1968. Holotype. — Adult male, skin and skull, KU 33451, from Cerro Tequila, 10,000 ft., 7 mi. S and 2 mi. W Tequila, Jalisco; obtained May 13, 1949, by J. R. Alcorn, original number 9186. Pappogeomys bulleri lutulentus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:612, August 5, 1968. Holotype. — Adult female, skin and skull, KU 92984, from Sierra de Cuale, 7300 ft., 9 km. N El Teosinte ( =Desmoronado), Jalisco; obtained October 28, 1962, by Percy L. Clifton, original number 3236. Pappogeomys castanops elibatus Russell, Univ. Kansas Publ., Mus. Nat. Hist, 16:672, August 5, 1968. 136 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Holotype.—Aduk female, skin and skull, KU 58092, from 12 mi. W San Antonio de las Alazanas, about 7500 ft., Coahuila; obtained January 10, 1954, by Robert W. Diekerman, original number 2268. Pappogeomys castanops parviceps Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:673, August 5, 1968. Holotype. — Adult female, skin and skull, KU 87152, from 18 mi. SW Ala- mogordo, 4400 ft., Otero Co., New Mexico; obtained June 30, 1961, by M. Raymond Lee, original number 4067. Pappogeomys castanops perexiguus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:676, August 5, 1968. Holotype. — Adult female, skin and skull, KU 55584, from 6 mi. E Jaco, Chihuahua, 4500 ft., in Coahuila; obtained March 18, 1953, by Gerd H. Hein- rich, original number 6262. Pappogeomys castanops pratensis Russell, Unix. Kansas Publ., Mus. Nat. Hist., 16:653, August 5, 1968. Holotype. — Adult female, skin and skull, KU 52051, from 8 mi. W and 3 mi. S Alpine, 5100 ft., Brewster Co., Texas; obtained December 30, 1952, by Gerd H. Heinrich, original number 5684. Pappogeomys castanops surculus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:688, August 5, 1968. Holotype. — Adult female, skin and skull, KU 62470, from La Zarca, Duran- go; obtained May 29, 1954, by Robert W. Diekerman, original number 3361. Remarks. — Left upper premolar missing. Pappogeomys castanops torridus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:665, August 5, 1968. Holotype. — Adult female, skin and skull, KU 84461, from 3 mi. E Sierra Blanca, about 4000 ft., Hudspeth Co., Texas; obtained August 13, 1960, by M. R. Lee, original number 2659. Pappogeomys tylorhinus brevirostris Russell, Univ. Kansas Publ., Mus. Nat. Hist., 16:733, August 5, 1968. Holotype. — Adult female, skin and skull, KU 66151, from 2 mi. E Celaya, 5800 ft., Guanajuato; obtained January 17, 1955, by Robert W. Diekerman, original number 4844. Remarks. — Tips of upper incisors missing. Cratogeomys castanops buUatus Russell and Baker, Univ. Kansas Publ., Mus. Nat. Hist., 7:597, March 15, 1955. Holotype.— Aduh female, skin and skull, KU 48498, from 2 mi. S and B'A mi. E Nava, 810 ft., Coahuila; obtained June 16, 1952, by Robert J. Russell, original number 276. Remarks. — Exposed portion of third upper molar missing on both sides. Arranged as Pappogeomys castanops huUatus by Russell (1968b:632). Cratogeomys castanops jucundus Russell and Baker, Uni\ . Kansas Publ., Mus. Nat. Hist., 7:599, March 15, 1955. Holotype. — Adult female, skin and skull, KU 56603, from Hermanas, 1205 ft., Coahuila; obtained December 5, 1953, In- Robert \V. Diekerman, original number 2051. Remarks. — Arranged as Pappogeomys castanops jucundus by Russell (1968b: 648). Jones and Genoways — Holotypes of Mammals 137 Cratogeoniys castanops soididulus Russell and Baker, Univ. Kansas Piihl., Mus. Nat. Hist., 7:600, March 15, 1955. Holotype. — Adult female, skin and skull, KU 56614, from IJ2 mi. NW Ocampo, 3300 ft., Coahuila; obtained December 16, 1953, by Robert W. Dickerman, original number 2164. Remarks. — Arranged as Pappogeomys castanops soididulus by Russell (1968b: 658). Cratogeomys castanops ustulatus Russell and Baker, Univ. Kansas Publ., Mus. Nat. Hist., 7:598, March 15, 1955. Holotype. — Adult female, skin and skull, KU 34589, from Don Martin, 800 ft., Coahuila; obtained August 19, 1949, by W. Kim Clark, original number 1034. Rouaiks. — Arranged as Pappogeomys castanops ustulatus by Russell ( 196815: 667). Cratogeoniys gymnurus atratus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 5:539, October 15, 1953. Holotype. — Adult female, skin and skull, KU 31880, from top of Cerro Viejo de Cuyutlan, 9700 ft., 19 mi. S and 9 mi. W Cuadalajara, Jalisco; obtained February 17, 1949, by J. R. Alcorn, original number 7902. Remarks. — Arranged as Pappogeomys tylorhinus atratus by Russell (1968b: 731). Cratogeomys gymnurus tellus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 5:537, October 15, 1953. Ho/of(//)C.— Adult female, skin and skull, KU 33454, from 3 mi. W Tala, 4300 ft., Jalisco; obtained June 2, 1949, by J. R. Alcorn, original number 9376. Remarks. — Arranged as Pappogeomys gymnurus tellus by Russell (1968a: 482, 571; 1968b:756). Cratogeoniys zinseri niorulus Russell, Univ. Kansas Publ., Mus. Nat. Hist., 5:541, October 15, 1953. Holotype. — Adult male, skin and skull, KU 36679, from N end Lago Sayula, 4400 ft., 9 mi. N and 2 mi. E Atoyac, Jalisco; obtained March 23, 1950, by J. R. Alcorn, original number 10889. Remarks. — Exposed portion of left upper incisor missing. Considered a synonym of Pappogeomys gymnurus gy?uniirus (Merriam, 1892) by Russell (1968b: 751). Cratogeomys zinseri zodius Russell, ITniv. Kansas Publ., Mus. Nat. Hist., 5:540, October 15, 1953. Holotype. — Adult male, skin and skull, KU 31879, from 13 mi. S and 15 mi. W Guadalajara, Jalisco; obtained February 6, 1949, by J. R. Alcorn, original number 7747. Remarks. — Exposed portion of left upper incisor and left lower third molar missing. Arranged as Pappogeomys tylorhinus zodius by Russell (1968a:535; 1968b:742). Perognathus flavescens cockrunii Hall, Univ. Kansas Publ., Mus. Nat. Hist., 7:589, November 15, 1954. Holoty pe.—Suhadu\t female, skin and skull, KU 13045, from 4)2 mi. NE Danville, Harper Co., Kansas; obtained December 1, 1939, by Sam Tihen, original number 99 of J. A. Tihen. Remarks. — Both zygomatic arches missing. 138 Misc. PuBL. 51, Univ. Kansas Mus. Nat. Hist. Perognathus flavus bunkeri Cockrum, Univ. Kansas Publ., Mus. Nat Hist 5:205, December 15, 1951. Holotype.— Adult female, skin and skull, KU 11716, from Conrad Farm, 1 mi. E Coolidge, Hamilton Co., Kansas; obtained July 1, 1936, by F. Parks and C. W. Hibbard, original nimiber 894 (Hibbard). Remarks.— Leit zygomatic arch missing, right ramus broken, and hole in right parietal. Perognathus flavus medius Baker, Univ. Kansas Publ., Mus. Nat Hist 7:343, February 15, 1954. Holotype.— Adult female, skin and skull, KU 48583, from 1 mi. S and 6 mi. E Rincon de Romos, 6550 ft., Aguascalientes; obtained July 14, 1952, by Rollin H. Baker, original number 2215. Remarks. — Right zygomatic arch missing. Perognathus flavus pallescens Baker, Univ. Kansas Publ., Mus. Nat Hist 7:345, February 15, 1954. Holotype.— Adult male, skin and skull, KU 40298, from 1 mi. SW San Pedro de las Colonias, 3700 ft., Coahuila; obtained February 9, 1951, by J. R. Alcorn, original number 14177. Perognathus flavus parviceps Baker, Univ. Kansas Publ., Mus. Nat. Hist 7:344, February 15, 1954. Holotype. — Adult female, skin and skull, KU 38402, from 4 mi. W and 2 mi. S Guadalajara, 5100 ft., Jalisco; obtained June 15, 1950, by J. R. Alcorn, original number 12020. Remarks. — Right zygomatic arch missing. Dipodomys ordii largus Hall, Univ. Kansas Publ., Mus. Nat. Hist. 5:40 October 1, 1951. Holotype.— Adult female, skin and skull, KU 27234, from Mustang Island, 14 mi. SW Port Aransas, Aransas Co., Te.xas; obtained June 30, 1948, by W. K. Clark, original number 543. Dipodomys ordii parvabullatus Hall, Univ. Kansas Publ.. Mus. Nat. Hist 5:38, October 1, 1951. Ho/of (//)c.— Adult male, skin and skull, KU 35454, from an island, 88 mi. S and 10 mi. W iMatamoros, Tamaulipas; obtained March 19, 1950, by E. R. Hall and Curt \on Wedel, original number 6778 (Hall). Remarks. — Both zygomatic arches missing and hole in right parietal. Reithrodontomys fulvescens meridionalis Anderson and Jones, Univ. Kansas Publ., Mus. Nat. Hist., 9:522, January 14, 1960. Holotype.— Adult male, skin and skull, KU 71388, from 9 mi. NNW Esteli, Esteli, Nicaragua; obtained July 15, 1956, by J. R. Alcorn, original number 21464. Reithrodontomys gracilis insularis Jones, Proc. Biol. Soc. Washington, 77:123, June 26, 1964. Holotype.— Adult male, skin and skull, KU 92262, from 8 mi. ENE Ciudad del Carmen, Isla del Carmen, Campeche; obtained July 7, 1962, by William C. Stanley, original number .373. Reithrodontomys spectabilis Jones and Lawlor, Univ. Kansas Publ., Mus. Nat. Hist., 16:413, April 13, 1965. Holotype.— Adult male, skin and skull, KU 92294, from 2}i km. N San Jones and Genoways — Holotypes of Mammals 139 Miguel, Isla Coziimel, Quintana Roo; obtained August 8, 1962, by Ticul AKarez, original numlier 848. Peromyscus angustirostris Hall and Alvarez, Proc. Biol. Soc. Washington, 74:203, August 11, 1961. H olotype. —0\d adult male, skin and skull, KU 83226, from 3 km. W Zacaulpan, 6000 ft., Veracruz; obtained April 12, 1960, by M. Raymond Lee, original number 1886. Remarks. — Regarded as a synonym of Peromtjscus furvtts J. A. Allen and Chapman, 1897, by Mus.ser (1964:12). Peromyscus boylii cansensis Long, Univ. Kansas Publ., Nhis. Nat. Hist., 14:101, December 29, 1961. Holotype. — Adult male, skin and skull, KU 81830, from 4 mi. E Sedan, Chautauqua Co., Kansas; obtained December 30, 1959, by C. A. Long, orig- inal number 456. Remarks. — Both zygomatic arches broken. Regarded as a synonym of Pero- myscus boylii attwateri J. A. Allen, 1895, by Choate et al. (1967:312). Peromyscus difficilis petricola Hoffmeister and de la Torre, Proc. Biol. Soc. Washington, 72:167, November 4, 19.59. Holotype. — Adult female, skin and skull, KU 33239, from 12 mi. E San Antonio de las Alazanas, 9000 ft., Coahuila; obtained August 2, 1949, by W. Kim Clark, original number 979. Remarks. — Left ramus broken. Peromyscus maniculalus ozarkiarum Black, Jour. Manim., 16:144, May 15, 1935. Holotype. — Adult male, skin and skull, KU 10104, from 3 mi. S Winslow, Washington Co., Arkansas; obtained August .30, 1934, by Ruby Black, original number 853 of J. D. Black. Remarks. — Right zygomatic arch broken. Peromyscus melanophrys coahuilensis Baker, L^ni\. Kansas Publ., Mus. Nat. Hist., 5:2.57, April 10, 19.52. Holotype. — Adult female, sldn and skull, KU 35019, from 7 mi. S and 1 mi. E Gomez Farias, 6500 ft., Coahuila; obtained November 20, 1949, by W. K. Clark, original number 1293. Remarks. — Skin with slippage on belly and right flank. In the original description in the statement of particulars about the holotype, the locality of capture was incorrectly given as "Gomez Farias, 6500 ft., Coahuila," although elsewhere in the paper it is located correctly. Peromyscus melanophrys micropus Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:255, April 10, 1952. Holotype. — Adult male, skin and skull, KU 31760, from 3 mi. N Guadala- jara, Jalisco; obtained January 18, 1949, by J. R. Alcorn, original number 7402. Remarks. — The date on which the holotype was obtained was incorrectly given in the original description as January 11, 1949. Peromyscus ochraventer Baker, Univ. Kansas Publ., Mus. Nat. Hist, 5:213, December 15, 1951. Holotype.— Aduh female, skin and skull, KU 36958, from 70 km. [by high- \\ay] S Ciudad Victoria and 6 km. W of the [Pan American] highway [at El Carrizo], Tamaulipas; obtained January 12, 1950, l)y William J. Schaldach, Jr., original number 566. 140 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Peromyscus truei erasmus Finley, Univ. Kansas Publ., Mus. Nat. Hist 5:265, May 23, 1952. Holotype.— Young adult female, skin and skull, KU 34417, from 8 mi. NE Durango, 6200 ft., Durango; obtained August 16, 1949, by J. R. Alcorn, original number 10255. Reryiarks. — Right z>'gomatic arch broken. Regarded as a synonym of Pero- mijscus truei gentilis Osgood, 1904, by Baker ( 1960:321 ). Baiomys musculus pullus Packard, Univ. Kansas Publ., Mus. Nat. Hist., 9:401, December 19, 1958. Holotype.— Aduh female, skin and skull, KU 71605, from 8 mi. S Condega, Esteli, Nicaragua; obtained July 15, 1956, by A. A. Alcorn, original number 4218. Baiomys taylori canutus Packard, Univ. Kansas Publ., Mus. Nat Hist 9:643, June 16, 1960. Holotype.— Adult male, skin and skull, KU 62075, from 1 mi. S Pericos, Sinaloa; obtained June 14, 1954, by A. A. Alcorn, original number 1754. Remarks. — Left ear missing and some slippage of pelage on left shoulder. Baiomys taylori fuliginatus Packard, Univ. Kansas Publ., Mus. Nat. Hist., 9:645, June 16, 1960. Holotijpe.— Adult male, skin and skull, KU 36765, from 10 mi. E and 2 mi. N Ciudad de Maiz, 4000 ft., San Luis Potosi; obtained January 17, 1950, by J. R. Alcorn, original number 10400. Sigmodon hispidus solus Hall, Uni\. Kansas Publ., Mus. Nat. Hist., 5:42, October 1, 1951. Holotype.— Adult male, skin and skull, KU 35468, from an island, 88 mi. S and 10 mi. W Matamoros, Tamaulipas; obtained March 22, 1950, by E. R. Hall and Curt \()n Wedel, original number 6806 (Hall). Remarks. — Hole in left orbit and left zygomatic arch cracked in region of infraorbital foramen. Neotoma albigula subsolana Alvarez, Univ. Kansas Publ., Mus. Nat. Hist., 14:141, April 30, 1962. Holotype.— Adult male, skin and skull, KU 56950, from Miquihuana, 6400 ft., Tamaulipas; obtained July 20, 1953, by Gerd H. Heinrich, original number 7553B. Neotoma angustapalata Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:217, December 15, 1951. Holotype. — Subadult male, skin, skull, and prepared baculum, KU 36976, from 70 km. [by highway] S Ciudad Victoria and 6 km. W of the [Pan Ameri- can] highway [at El Carrizo], Tamaulipas; obtained January 14, 1950, by William J. Schaldach, Jr., original number 578. Neotoma mexicana eremita Hall, Jour. Washington Acad. Sci., 45:328, October 31, 1955. Holotype. — Adult female, skin, skull, and body skeleton, KU 64532, from 1 mi. S San Francisco, 50 ft., Nayarit; obtained January 27, 1955, by J. R. Alcorn, original number 17830. Neotoma mexicana scopulorum Finley, Univ. Kansas Publ., Mus. Nat. Hist., 5:529, August 15, 1953. Jones and Genoways — Holotypes of Mammals 141 Hohttjpe.—0]d adult male, skin and skull, KU 37137, from 37° 47' N, 103° 28' W, 3 mi. WV Higbee, 4300 ft., Otero Co., Colorado; ol)tained May 16, 1950, by R. B. Finley, Jr., original number 500516-1. Remarks. — Left upper first molar appears to ha\e been lost in life. Nelsonia neotomodon cliftoni Cenoways and Jones, Proc. Biol. Soc. Wash- ington, 81:97, April 30, 1968. Holotii])c.—\i\\\\i female, skin , and skull, KU 1094.37, from 2;^ mi. ENE Jazmin, 6800 ft., Jalisco; obtained October 20, 1966, by Percy L. Clifton, original number 11706. Microtus montanus codiensis Anderson, Univ. Kansas Publ., Mus. Nat. Hist., 7:497, July 23, 1954. Holotype. — Adult female, skin and skull, KU 27578, from 3 1/5 mi. E and 3/5 mi. S Cody, 5020 ft.. Park Co., Wyoming; obtained August 11, 1948, by James W. Bee, original number 18-8-11-48. Microtus montanus pratincolus Hall and Kelson, Uni\. Kansas Publ., Mus. Nat. Hist., 5:75, October 1, 1951. Holotype. — Adult female, skin and skull, KU 34004, from 6 mi. E Hamil- ton, .3700 ft., Ravalli Co., Montana; obtained August 14, 1949, by John A. White, original number 477. Remarks. — Subspecilic name emended to pratincola by Hall and Cockrum (1953:417). Microtus montanus zygomaticus Anderson, Univ. Kansas Publ., Mus. Nat. Hist., 7:500, July 23, 1954. Holoiypc. — Adult male, skin and skull, KU 32761, from Medicine Wheel Ranch, 9000 ft., 28 mi. E Lo\ell, Big Horn Co., Wyoming; obtained July 8, 1949, by R. Freiburg, original number 105. Microtus ochrogaster taylori Hibbard and Rinker, Univ. Kansas Sci. Bull., 29:256, October 15, 1943. Holotype. — Adult female, skin and skull, KU 14126, from U2 mi. N Fowler, Meade Co., Kansas; obtained June 17, 1942, by George C. Rinker, original number 1195 of C. W. Hibbard. Remarks. — Hole in left auditory bulla. Microtus pennsylvanicus alcomi Baker, Univ. Kansas Publ., Mus. Nat. Hist, 5:105, November 28, 1951. Holotype. — Adult female, skin and skull, KU 21552, from 6 mi. SW Kluane, 2550 ft., Yukon Territory, Canada; obtained August 24, 1947, by J. R. Alcorn, original number 5240. Microtus pennsylvanicus finitus Anderson, Univ. Kansas Publ., Mus. Nat. Hist, 9:96, May 10, 1956. Holotype. — Adult female, skin and skull, KU 50204, from 5 mi. N and 2 mi. W Parks, Dundy Co., Nebraska; obtained August 16, 1952, by J. Knox Jones, Jr., original number 906. Remarks. — Right zygomatic arch broken. Microtus pennsylvanicus pullatus Anderson, Univ. Kansas Publ., Mus. Nat. Hist., 9:97, May 10, 1956. Holotype. — Adult male, skin and skull, KU 37873, from 12 mi. N and 2 mi. E Sage, 6100 ft., Lincoln Co., Wyoming; obtained July 19, 1950, by Rollin H. Baker, original number 1343. 142 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Microtus pennsylvanicus tananaensis Baker, Univ. Kansas Publ., Mus. Nat. Hist., 5:107, November 28, 1951. Holotype. — Adult female, skin and skull, KU 21509, from Yerrick Creek, 21 mi. W and 4 mi. N Tok Junction, Alaska; obtained July 20, 1947, by J. R. Alcorn, original number 5023. Remarks. — Left auditory bulla broken. Microtus pennsylvanicus uligocola Anderson, Univ. Kansas Publ., Mus. Nat. Hist., 9:94, May 10, 1956. Holotype. — Adult male, skin and skull, KU 26898, from 6 mi. W and 32 mi. S Loveland, 5200 ft., Larimer Co., Colorado; obtained July 26, 1948, by James O. Lounquist, original number 349. Synaptomys cooperi paludis Hibbard and Rinker, Univ. Kansas Sci. Bull., 28:26, May 15, 1942. Holotype. — Adult male, skin and skull, KU 13713, from Meade County State Park, 14 mi. SW Meade, Meade Co., Kansas; obtained July 12, 1941, by Claude W. Hibbard, original number 528. Synaptomys cooperi relictus Jones, Univ. Kansas Publ., Mus. Nat. Hist., 9:387, May 12, 1958. Holotype. — Adult female, skin and skull, KU 51617, from Rock Creek Fish Hatchery, 5 mi. N and 2 mi. W Parks, Dundy Co., Nebraska; obtained Novem- ber 1, 1952, by J. Knox Jones, Jr., original number 995. Zapus hudsonius pallidas Cockrum and Baker, Proc. Biol. Soc. Washington, 63:1, April 26, 1950. Holotype. — Adult male, skin, skull, and body skeleton, KU 22953, from NW corner sec. 4, T. 12 S, R. 20 E, 6)2 mi. N and 1%, mi. E Lawrence, Douglas Co., Kansas; obtained May 4, 1948, by E. Lendell Cockrum and Rollin H. Baker, original number 916 (Cockrum). Carnivora Taxidea taxus kansensis Schanz, Jour. Mamm., 31:346, August 21, 1950. Holotype. — Adult female, tanned (cased) skin and skull, KU 21989, from 4 mi. SE McLouth, Leavenworth Co., Kansas; obtained November 30, 1947, by Henry Murr and prepared by James O. Lounquist, original number 46. Remark.^. — Bullet hole entering skull through right parietal and leaving through right alisphenoid, but braincase intact. The taxonomic status of this nominal subspecies is uncertain because the species is in need of systematic review. Mephitis macroura eximius Hall and Dalquest, Univ. Kansas Publ., Mus. Nat. Hist., 1:579, January 20, 1950. Holotype.— Adult female, skin and skull, KU 19272, from 15 km. W Piedras Negras, 300 ft., Veracruz; obtained January 13, 1947, by J. Mazza and Walter W. Dalquest, original number 7017 (Dalquest). Geographic Origin of Type Specimens The countries, states, and territories whence originated the holotypes in the foregoing list are here arranged alphabetically. Names of species and sulispecies are listed alphabetically, in the combination used in the original description, under the place names. Jones and Genoways — Holotypes of Mammals 143 Canada Yukon Territory Microtus pennsylvanicus alcorni Baker Cuba Lasiuiu.s intermedins iusularis Hall and Jones Mexico Aguascalientes Peio^nathus ftaviis mcdius Baker Campeche Reithrodontomys gracilis iusularis Jones Coahiiila C ratogeomys castanops hullatus Russell and Baker Cratugeomys castanops jucundiis Russell and Baker Craiogeomys castanops sordidnhis Russell and Baker Crato'^eomys castanops nstnlatus Russell and Baker Leptonycteris nivalis longala Stains Myotis planiceps Baker Pappogeomys castanops elihatus Russell Fappogeomys castanops perexiguus Russell Perognathus flavus pallescens Baker Peromyscus clifficilis petricola Hoftmeister and de la Torre Peromyscus melanophrys coahiiilensis Baker Pipistrellus subflavus clams Baker Scalopus montanns Baker Sylvilagus floridanns nelsoni Baker Thomomys hottae angustidens Baker Thomomys hottae humulis Baker Thomomys hottae retractus Baker Thomomys hottae villai Baker Durango Pappogeomys castanops surculus Russell Peromyscus truei erasmus Finley Guanajuato Pappogeomys tylorhinus hrevirostris Russell Jalisco Cratogeomys gymnurus atratus Russell Cratogeomys gymnurus tellus Russell Cratogeomys zinseri morulus Russell Cratogeomys zinseri zodius Russell , Cryptotis euryrhynchis Genoways and Choate Molossops greenhalli mexicanus Jones and Genoways Nelsonia neotomodon cliftoni Genoways and Jones Pappogeomys alcorni Russell Pappogeomys hulleri infuscus Russell Pa))pogeomys hulleri lutulentus Russell Perognathus flavus parviceps Baker Peromyscus melanophrys micropus Baker Nayarit Neotoma mexicana eren^ita Hall Quintana Roo Reithrodontomys spectabilis Jones and Lawlor San Luis Potosi Baiomys taylori fuliginatus Packard Sinaloa Baiomys taylori canutus Packard Sturnira ludovici occidentalis Jones and Phillips Thomomys umhrinus varus Hall and Long 144 Misc. Publ. 51, Una'. Kansas Mus. Nat. Hist. Tamaiilipas Dipodomy.s oidii paivahuUatiis Hall Lepiis colifornicus ctirti Hall Myotis evotis auriculus Baker and Stains Neotoma alhigula siibsolana AKarez Neotoma angusiapalata Baker Pewtuysciis ocliravcntcr Baker Sigmoiloit liispidu.s solus Hall SpermophiUis spilosoma oricohis Alvarez Veracruz Heterogeomys hispid us latirostris Hall and Alvarez Mephitis macrouio eximius Hall and Dalqiiest Myotis argentatus Dalquest and Hall Myotis ck'gans Hall Myotis nigricans dalquesti Hall and Alvarez Natahis mexicanus saturatus Dalquest and Hall Peromyscus angustirostris Hall and Alvarez Mozambique Nycteris vinsoni Dalquest ScotO))JiiIus alvenslehcni Dalquest Nicaragua Baiomys miisculus puUus Packard Reithrodontomys fulvescens meridionalis Anderson and Jones United States Alaska Microtus pennsylvanicus tananaensis Baker Arizona Myotis velifer hrevis Vaughan Tliomomys bottae caneloensis Lange Arkansas Feromyscus maniculatus ozarkiarum Black Colorado Eutamias umbrinus montanus White Microtus pennsylvanicus tdigocola Anderson Neotoma mexicana scopuJoruni Finley Tliomomys bottae rubidus Youngman Idaho Ochotona princeps howelli Borell Kansas Antrozous bunkeri Hibbard Geomys bursarius industrius Villa-R. and Hall Marmota monax hunkeri Black Microtus ochrogaster taylori Hibbard and Rinker Perognathus flavescens cockrunii Hall Perognathus fiavus hunkeri Cockrinn Peromyscus boyUi cansensis Long Synaptomys cooperi pahidis Hibbard and Rinker Taxidea taxus kanscnsis Schanz Zapus Jiudsoiiius ])uUidus Cockruni and Baker Montana Microtus montanus pratincohis Hall and Kelson Nebraska Microtus pennsylvanicus finitus Anderson Syiiaptomys coo))eri rehctus Jones New Mexico Pappogeomys castanops parviceps Russell Jones and Genoways — Holotypes of Mammals 145 Texas Dipodomijs ordii largus Hall Fappogeomijs castanops pratcnsis Russell Fappogeomijs castanops tonidus Russell Wyoming Etitaiiiias viininuis silvatictis White EutuDiias uiiihiiiitis frcnionti White Lepus arnericanus seclusiis Baker and Hankins [=zLcptis arnericanus sctzeri Baker] Microtiis nionta)ius codiensis Anderson Microtus niontanus zt/gornaticus Anderson Microtiis ))ennsiilvanicus puUatus Anderson Myotis tlujsanodes pahasapensis Jones and Genoways Ochotona princeps ohscura Long Tlionionu/s talpoides attenuatus Hall and Montague Tlionioniiis talpoides merittis Hall Tlioniontijs talpoides rostralis Hall and Montague Venezuela Eumops perotis renatae Pirlot Literature Cited Allen, J. A. 1895. On the species of the genus Reithrodontomys. Amer. Mus. Nat. Hist, 7:107-143. Anderson, S. 1966. Taxonomy of gophers, especially Thomorntis in Chihuahua, Mexico. Syst. Zool, 15:189-198, 6 figs. Baker, R. H. 19.59. Substitute name for Lepus arnericanus seclusus Baker and Hankins. Jour. Manini., 40:145. 1960. Mammals of the Guadiana Lava Field, Diuango, Mexico. Publ. Mus. Michigan State Univ., Biol. Ser., l:.30.3-.328, 3 figs. Choate, J. R., C. J. Phillips, and H. H. Genoways 1967. Taxonomic status of the brush mouse, Peromifscus hoylii cansensis Long, 1961. Trans. Kansas Acad. Sci., 69:306-313, 2 figs. Dalquest, W. W. 1966. Scotopliilus alvenslebeni Dalquest a synonym of Scotoi^hihis gigas Dobson. Jour. Mamm., 47:134. Davis, W. B., and D. C. Carter 1962. Review of the genus Leptonycteris ( Mammalia :Chiroptera). Proc. Biol. Soc. Washington, 75:193-198. DUNMGAN, P. B. 1967. Pocket gophers of the genus Thomomys of the Mexican state of Sinaloa. The Radford Review, 21:139-168, 4 figs. Fixdley, J. S. 1960. Identity of the long-eared myotis of the Southwest and Mexico. Jour. Mamm., 41:16-20, 1 pi., 1 fig. Genoways, H. H., and J. K. Jones, Jr. 1969. Taxonomic status of certain long-eared bats (genus Myotis) from the southwestern United States and Mexico. Southwestern Nat., 14:1-1.3, 5 figs. Goldman, E. A. 1914. A new bat of the genus Mimon from Mexico. Proc. Biol. Soc. Washington, 27:75-76. Goodwin, G. G. 1959. Bats of the subgenus Natalus. Amer. Mus. Novit., 1977:1-22, 2 figs. 146 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Hall, E. R., and E. L. Cockrum 1953. A synopsis of the North American Microtine rodents. Univ. Kansas Pul)l., Mus. Nat. Hist., 5:373-498, 149 figs. Hall, E. R., and K. R. Kelsox 1959. The mammals of North America. Ronald Press, New York, l-.xxx -\- 1-546 + 79 and 2:viii + 547-1083 + 79, illustrated. Handley, C. O., Jr. 1966. Checklist of the mammals of Panama. Pp. 753-793, in Ectoparasites of Panama (R. L. Wenzel and V. J. Tipton, eds.). Field Mus. Nat. Hist., Chicago, xii + 861 pp., illustrated. Jones, J. K., Jr., E. D. Fleharty, and P. B. Dunnigan 1967. The distributional status of bats in Kansas. Misc. Publ., Mus. Nat. Hist., Univ. Kansas, 46:1-33, 11 figs. Krutzsch, p. H., and T. A. Vaughan 1955. Additional data on the bacula of North American bats. Jour. Mamm., 36:96-100, 1 fig. Long, C. A. 1965a. The mammals of Wyoming. Univ. Kansas Pub!., Mus. Nat. Hist., 14:49.3-758, 82 figs. 19651). Taxonomic status of the snowshoe rabbit, Le])us (imericantis sechisiis Baker and Hankins. Proc. Biol. Soc. Washington, 78:125-126. Morse, R. C, and B. P. Glass 1960. The taxonomic status of Antrozous htmkeri. Jour, Mamm., 41:10- 15, 2 figs. Musser, G. G. 1964. Notes on geographic distribution, habitat, and taxonomy of some Mexican mammals. Occas. Papers Mus. Zool., Univ. Michigan, 636: 1-22, 1 fig. PaTTON, J. L., AND R. E. DiNGMAN 1968. Chromosome studies of pocket gophers, genus Thomomijs. I. The specific status of Thomomijs umhrinus (Richardson) in Arizona. Jour. Mamm., 49:1-13, 8 figs. PiRLOT, P. 1968. Chiropteres du Perou, specialement de Haute- Amazonie. Mam- malia, 32:86-96, 2 figs. Raun, G. G. 1965. The subspecific status of the cottontail, Sijlvilagus ftoridamis, in northern Coahuila, Mexico. Jour. Mamm., 46:519-521. Russell, R. J. 1968a. Evolution and classification of the pocket gophers of the subfamily Geomyinae. Univ. Kansas Publ., Mus. Nat. Hist., 16:473-579, 9 figs. 1968b. Revision of pocket gophers of the genus Pappogeomys. Uni\-. Kan- sas Publ., Mus. Nat. Hist., 16:581-776, 10 figs. ECOLOGY OF POCKET GOPHERS OF MESA VERDE, COLORADO BY Charles L. Douglas The Mesa Verde land mass consists of about 200 square miles of plateau country in southwestern Colorado near the Four Corners, where Colorado, Utah, Arizona, and New Mexico have a common boundary. The Mesa Verde, named by early Spanish explorers of the Southwest, is the remnant of a plateau laid down by late Creta- ceous seas. Erosion has dissected the plateau until it is now a cuesta consisting of long, finger-like mesas joined at their northern ends but otherwise separated from each other by deep canyons (Figs. 1-3). In 1906, part of the land mass was set aside, by Con- gress, as Mesa Verde National Park in order to preserve dwellings of prehistoric Indians, for which the area is famous. Today, more than 52,000 acres are included within the boundaries of the park. Elevations in Mesa Verde National Park range from 8572 feet at Park Point down to about 6500 feet at the southern ends of the mesas, where the canyons are from 600 to 900 feet deep. Mesa Verde is in the pinyon-juniper climax region that extends through much of the Southwest; and pinyon-juniper woodland is the domi- nant canopy cover on the tops of the mesas. Oak chaparral and mixed shrubs occur on slopes. Past fires apparently have permitted establishment of a shrub zone at some of the higher elevations. Sagebrush grows in the bottoms of canyons and in many of the drainages on top of the mesas, and also persists as a late successional stand on the disturbed soil around prehistoric surface dwellings. Stands of Douglas fir occurs on many of the cooler north-facing slopes where micro-climates are favorable for its growth. Indixidual trees and small stands of ponderosa pine are found in sheltered places throughout the Mesa Verde. Climatically the Mesa Verde is semi-arid. Precipitation has averaged about 18 inches each year for the past 45 years, with July and August generally having the most precipitation. Precipitation is heavier on the higher, northern end of the park than on the southern end, owing to the proximity of the northern parts of the park to the nearby La Plata Mountains. (147) 148 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. I08°30' I08°25' 37° 15' 37° 10' UTE MOUNTAIN INDIAN RESERVATION 10,000 FEET MESA VERDE NATIONAL PARK AND VICINITY MONTEZUMA COUNTY COLORADO I08°30' I08°25' Fig. 1. Map of Mesa Verde National Park and vicinity, showing localities at which specimens of pocket gophers have been collected. Interdisciplinary research recently conducted under the auspices of the Wetherill Mesa Archeological Project has resulted in reports on mammals of the park ( Douglas, 1963, 1967a, 1967b ) , on amphib- ians and reptiles (Douglas, 1966), on plants (Erdman, 1962; Erd- man et al, 1962; Welsh and Erdman, 1964; Fritts et ah, 1965; Doug- las and Erdman, 1967), and a report on climatic conditions in the Douglas — Pocket Gophers of Mesa Verde 149 park is in press. Earlier zoological studies include a report on mam- mals by Anderson ( 1961 ) . Pocket gophers, Tliomomys bottae aureus, are found in Mesa Verde along roadsides where soil has been disturbed, in grassy meadows, in stands of sagebrush, and in the shrub zone along the north rim of the park. Gophers occasionally are found in openings in the pinyon-juniper \\'oodland, in oak brush, and in rocky areas that do not appear to offer adequate conditions for fossorial animals. The diversity of habitats used by gophers led me to study their ecology in Mesa Verde. This report is the first to result from these studies. Gophers were studied periodically from 1962 through 1967. Field notes were kept on locations and activities of colonies and indi\iduals from 1961 through 1963. Trapping and analyses of habitats was begun in 1963 and continued through 1967. Most of the gophers trapped for use in this study were caught in 1965 and 1967. Twenty-eight months were spent in residence in Mesa Verde National Park from 1961 through 1964; also, I visited the park from August 10 to 16, 1965, April IS to May 5, 1967, and September IS to 30, 1967, to study pocket gophers. Distribution of Gophers in Mesa Verde Gophers have been collected in Mesa Verde at the places shown in Figure 1; the localities are listed below under "specimens exam- ined" and "other locality records." Specimens listed under the latter heading have not been examined by me. Specimens housed in various collections are designated as follows: Museum of Natural History, Uni\'ersity of Kansas (KU); United States National Mu- seum (USNM); Mesa Verde National Park (MV); Museum of Verte- brate Zoology, University of California ( M VZ ) . Specimens presently in my personal collection are listed by locality, followed in paren- theses by the number of indi\'iduals. A total of 132 specimens from Mesa Verde were examined and measured. To the best of m\' knowledge, the specimens listed below represent all gophers that ha\'e been taken in the park. Specimens examined. — Total 132, as follows: Mancos River, 6200 ft. ( KU 69307-69315); head Prater Canyon, 7700 ft. (13); Upper Well, Prater Canyon, 7575 ft. (KU 69279); Prater Canyon, 7500 ft. ( KU 7.5977); ^i mi. N Middle Well, Prater Canyon, 7,500 ft. ( KU 69280); Midd'e Well, Prater Canyon, 7.500 ft. (KU 69281-69285); 6.8 mi. S North Rim, Moccasin Mesa ( KU 1020.58); 8 mi. S North Rim, Moccasin Mesa (20 and also KU 1020.59-102061); 9 mi. S North Rim, Moccasin Mesa (2); Morfield Canyon, 7600 ft. (KU 75978); 150 Misc. PuBL. 51, Unw. Kansas Mus. Nat. Hist. Fig. 2. View of Navajo Canyon looking northward toward the confluence with Spruce Canyon. At this point, the canyon bottom is 600 feet lower than the tops of the mesas. Park Point, 8400-8500 ft. (16 and also KU 102047-102048, 102050-102057); ?i mi. S, 1% mi. W Park Point, 8000 ft. (KU 69286-69288); 1!^ mi. S, 1% mi. W Park Point, 8000 ft. (KU 69289); VA mi. S, 2 mi. W Park Point, 8075 ft. (KU 69290); sec. 27, head East Fork, Navajo Canyon, 7900 ft. (KU 69291-69292); sec. 27, head East Fork, Navajo Canyon, 7875 ft. ( 1 ); head West Fork, Navajo Canyon (1); J2 mi. N Far View Ruins, 7825 ft. (KU 69293); Far View Ruins, 7700 ft. (KU 69294); 100 yds. W Far View Ruins (1); 200 yds. W Far \'iew Ruins (6); 300 yds. W Far View Ruins (3); Far View Ruins, )i mi. W Highway (1); Drainage 'A mi. S Far View Ruins (1); 200 yds. S Far View Ruins (1); Douglas — Pocket Gophers of Mesa Verde 151 ■4 mi. S Far View Ruins Road, 30 ft., E Highway (2); 1 mi. SW Far View Ruins (2); 1.2 mi. S Far View Ruins Road (1 and KU 102062); 100 yds. N Wetherill Lab, 7050 ft., Cliapin Mesa (2); Residence Area, 7000 ft., Chapin Mesa (1); N Rim, Wetherill Mesa, 8239 ft. (2); 3 mi. N Rock Springs, 8200 ft. (KU 69295-69298); 2.2 mi. N Rock Springs (1); 2M mi. N, M mi. W Rock Springs, 8100 ft. (KU 69299-69301); 2 mi. N, Y, mi. W Rock Springs, 7900 ft. (KU 69302-69303); 1 mi. NNW Rock Springs, 7600 ft. (KU 69304); Y^ mi. NNW Rock Springs, 7500 ft. (KU 69305); Rock Springs, 7400 ft. (1 and KU 69306). Other locality records.— Frater Canyon, 7600 ft. ( MVZ 74408-74410); Far View Ruins, 7700 ft. (MV 7852/507, 7853/507); Mesa Verde, northern end, 8100 ft. (USNM 149087). The distribution of gophers is influenced by a complex inter- relationship of edaphic and climatic factors. Since gophers spend most of their lives in subterranean tubes, it is important that the soil in which they live be of sufficient depth to permit development of feeding tunnels as well as deeper living chambers where micro- environmental variables are more constant. Friability and constitu- ency of soils influence the ability of gophers to dig new tunnels and the amount of friability undoubtedly affects gaseous exchanges be- tween air in the tunnels and air in the interstices of the soil (see Kennerly, 1964). Soils on mesa tops are loessal in origin; the earliest preserved loess in Mesa Verde probably is Sangamon in age (Arrhenius and Bonatti, 1965 ) . Soils in Mesa Verde generally are shallow, although deeper soils occur in some saddles between ridges along the northern rim of the land mass, and in the bottoms of canyons where deep, sandy alluvial terraces occur. It was observed early in the study that gophers occurred in a variety of vegetational associations within Mesa Verde. Soils in these associations ranged from deep, sandy alluvium found in drain- ages, to the shallow soils of the pinyon-juniper woodland. In some places, gophers dug tunnels through hard layers of subsurface caliche, and numerous pieces of it were present in their mounds. In a former gravel storage area, gophers dug to the surface through about one foot of hard-packed gravel that was almost impossible to excavate with a shovel. On Park Point, individuals dug through a residual layer of loose rock to deposit rock-filled soil above ground. In other areas on Park Point they dug small contorted tunnels around and between subsurface boulders in areas that offered little in the way of soil and vegetation. In order to learn more about the composition of soils in gopher habitats, samples of soil were collected from the top two inches of 152 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. *^*.* ^' ..Ml f'.^' ■*' ''•^♦■« V Fig. 3. Prater Canyon near upper well, looking southward. Pocket gophers live in the sedge- and grass-covered soils of the canyon. the surface in 18 of the major trapping localities ( Table 1 ) . These samples were analyzed for particle size by the hydrometer method, which permits rapid determinations of percentages of clay, silt, and sand (Bouyoucos, 1967). The results of the hydrometer analyses are given in Table 1. Each of the values listed in this table represents an average of duplicate samples. The soils from various gopher habitats are moderately fine to medium in texture, and arc classified as silty clay loam ( 27 to 40 per cent clay ) , silty loam ( 40 per cent or more silt ) , or as sandy clay loam ( up to 39 per cent silt ) . Of much more im- portance than the classification of the soils is the fact that mod- erately fine to medium soils have excellent capacities for retaining moisture, being surpassed only by fine soils containing more than 40 per cent clay. Available moisture is defined as that percentage between field capacity and wilting point, and is expressed in inches of moisture per foot of soil. The range and average values of avail- able moisture for soils in the state of Colorado are as follows: moderately fine, 1.6-2.5, axerage 2.2; medium (40 per cent or more silt), 1.6-2.5, average 2.3; medium (0 to 39 per cent silt), 1.5-2.4, average 1.9 inches per foot (Orville Parsons, personal communica- tion ) . Douglas — Pocket Gophers of Mesa Verde 153 Table 1. — Percentages of clay, silt, and sand occurring in soil samples FROM VARIOUS LOCALITIES IN MeSA VeRDE NATIONAL PaRK, AS DETERMINED BY THE HYDROMETER METHOD. Locality Clay Silt Sand Park Point 23.60 43.10 33.30 Park Point, 8500 ft 16.10 29.10 54.80 Park Point, 8400 ft. 1 11.60 45.55 42.85 200 >ds. W Far View Rnins 16.40 36.85 46.75 300 yds. W Far View Ruins 24.15 30.15 45.70 300 yds. W Far View Ruins 31.70 32.90 35.40 1 mi. SW Far View Ruins 26.10 35.10 38.80 200 vds. W Far View Ruins 19.50 39.25 41.25 North Rim Wetherill Mesa 12.60 48.10 39.30 2.2 mi. N Rock Springs 15.10 50.60 34.30 Prater Canyon, 7600 ft. 17.30 23.90 58.80 Prater Canyon, 200 yds. S Highway ._ 30.00 37.00 33.00 Moccasin Mesa, northern end 11.30 52.70 36.00 Head Meadow, 8 mi. S North Rim, Moccasin Mesa 20.80 45.75 33.45 Meadow, Moccasin Mesa, 8 mi. S North Rim 25.65 43.05 31.30 Meadow, Moccasin Mesa, 8 mi. S North Rim 27.00 45.20 27.80 Meadow, Moccasin Mesa, 8 mi. S North Rim 24.00 51.20 24.80 100 yds., N Wetherill Lab, Capin Mesa 18.50 33.80 47.70 It was somewhat unexpected to find so much variation in samples from the same general area. Nevertheless, soils in Mesa Verde are known to occur in mozaic patterns, and variation in soil composition within a valley, or between various elevations on a ridge, such as Park Point, probably is to be expected. Probably the most important factor determining distribution of gophers is vegetational ground cover. Distribution of various plants of importance to gophers is regulated by the distribution of soils suitable for their growth and by amounts of nutrients and moisture available in such soils. Factors such as the tolerance of a plant for shade or sunlight, the serai stage in which the plant usually occurs, kinds of dispersal agents, chemical factors in the soil, and more, play regulatory roles in the ability of plants to invade certain areas. When species of plants are heavily cropped by gophers, the ability to grow new roots may be a limiting factor in the survival of such .species in areas used by gophers. Some plants, such as Poa fendleriona, are common to various ^'egetational associations within Mesa Verde, whereas others are restricted to a particular association. In order to analyze the rela- tionship of plants to the distribution of gophers, the vegetation was analyzed at each major trapping locality. Nineteen of the trapping sites were chosen for intensi\'e analysis of the vegetation. The sites were selected to include various associations, and all localities at which particle sizes of the soils had been analyzed. The dominant 154 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. and codominant species of plants were determined at each site, then other species were Hsted in order of their relative abundance. More than 70 species of plants were recorded from the 19 sites. The most abundant plants in gopher habitats consisted of about 30 species; these are listed below in order of their relative number of occur- rences : Foa fendleriana Eriogonum racemosum Pensfeiuon linarioicles Amelanchier utalicnsis Solidago petradoria Pinus edulis Junipenis osieosperma Aster higelovii Chnjsothammis depressus Lupiniis argenteus Astiagahis scoptdortim Artemisia tridentata Artemisia nova Lithosperm iim niderale Purshia tridentata Erigeron speciosus Artemisia ludoviciana Eriogonum nmhellatum SpJiaeraJcea coccinea Tragopogon pratensis Achillea millefoliurn Clienopodittm sp. ChrysotJwmmis nauseosus Comandra umbellata Koeleria cristata Stipa comafa Opuntia sp. Castilleja chrom,osa Erigeron flagellaris Fcndlera rupicola The ground cover at the head of Prater Canyon was composed mostly of Carex praegraciUs, Equlsetiim sp., and Agropyron deser- torum. Although these species were of major importance to a large colony of gophers at this site, they were found only at this locality and therefore did not rank among the 30 most abundant species listed above. The first 10 species of plants listed above are widely distributed in Mesa Verde. Of these, six species (or in two cases closely related species ) were eaten by captive gophers ( Table 2 ) . It seems reason- able to assume that when a species is found in more than half of the 19 localities it is utilized by gophers. Plants such as Chnjso- thamnus sp., having numerous, succulent roots, probably are utilized more than plants such as Aster higelovii, which has only one major root. Plants with widespreading root systems can be cropped re- peatedly whereas plants with fewer roots may be killed after the first severe cropping. Gophers influenced changes in vegetation from year to year by their selection of certain species. This was especially evident in the meadow of Moccasin Mesa. In 1965, tunnels of gophers were found under almost every clump of cactus {Opuntia sp.) occurring in the meadow. In some cases the entire underground parts of the plants were eaten and the part above ground was pulled partly into a Douglas — Pocket Gophers of Mesa Verde 155 Table 2. — Food items consumed by captives of Tliomomijs hottae {-\-, EATEX; O, NOT EATEN; , NOT OFFERED). Plant Roots Stem Leaves Other Artemisia frigida — + + — Artemisia hidoviciana + + 0 — Aster higelovii + > + + flowers Astragalus seopuJoriim + + o — Castilleja cliromosa + + + — CJirysopsis villosa + + + (basal) — Chnisothamnus nauseosus - + + — — Eqtiisetutn sp. + — — — Fendlera riipieola — + — — Liipinus caiidatus + + — — Pcdicidaris centranthera _— + + + — Penstcmon linarioides + + + — Querciis gamhelii + — — acorns Solidago petradoria + + — — SpJiaeralcea coccinea + o o — burrow. Some clumps of cacti recovered by 1967, but others died out completely and the area was invaded by primary successional species such as Sphaeralcea coccinea. Climatic factors affecting plants may also cause gophers to shift their area of activity, thereby allowing recovery of the vegetation in the former area of concentration. In 1965, moisture from heavy winter snows and spring rains promoted a luxuriant growth of grasses and herbs on Moccasin Mesa (see Fig. 4). Tn the autumn of that year, vegetation in the meadow was dense and gophers were concentrated around the periphery of the meadow at the edges of the pinyon-juniper woodland. Only a few gophers were found in the meadow. In this case, many more roots were available in the meadow than in the relatively sparse ground cover of the wood- land. The next year vegetation in the meadow was more normal in density, and gophers were again concentrated there. I suppose that gophers preferred the deeper soils and more abundant plants in the meadow, but were concentrated in the more sparsely vege- tated areas when plants in the meadow became too dense for unhampered movement or vision above ground, because gophers appear to avoid tall, dense vegetation. Gophers move tons of soil each year (Kennerly, 1964; Down- hower and Hall, 1966). Mounds often cover the surface sufficiently to prevent further growth of the underlying vegetation. Succession of plants on mounds then progresses as it would on any denuded ground, but because of the relatively small area covered by each mound, succession is fairly rapid. Mound obliteration in Mesa Verde customarily takes two or three years, whereas larger denuded 156 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. «««• % 'yt.. «*?.-■ .•«i..:*R it- Fig. 4. Meadow on Moccasin xMesa, S mi. S i\oith Rim. Heavy precipitation in winter and spring of 1967 promoted the unusually luxuriant growth of grasses shown here. areas require longer to recover. An example of the slow rate of succession in Mesa Verde is seen on the northern part of Wetherill Mesa, which burned in 1934. In 1967 this area supported shrubs, grasses, and herbaceous species, but pinyon and juniper seedlings had not become re-established despite the presence of unburned woodland adjoining the area. Likewise, in 1961, seedlings of pinyon and juniper were just becoming established in a large area on Chapin Mesa that was burned in 1858. In June of 1964, stakes were placed beside each of 20 new gopher mounds in the meadow on Moccasin Mesa (see Fig. 5). These mounds were inspected in the autumn of 1964 and again in 1965 and 1967, in order to learn which species of plants were early invaders of such disturbed soil. No new vegetation appeared on the mounds in 1964. In August, 1965, Sphaeralcea coccinea and Tragopogon pratensis were present. In May, 1967, SpJtaeralcea coc- cinea, Tragopogon pratensis, Artemisia dracunculus, and Foa pra- tensis grew on the mounds. Douglas — Pocket Gophers of Mesa Verde 157 ». P'.' A ...'i\g •'^'•' ' ' ■ ', '.' ..^*^^" '«<,t«»» 5 "rC ^ •''s';^-1k;. Fig. 5. Photograph of gopher habitat in meadow on Moccasin Mesa. Mounds made, and staked, in 1965 were nearly obliterated in two years time (photo- graph taken in September, 1967). Individuals of Thomomys browse above ground around the openings of burrows. Exidence of feeding usually is found on plants within a six- to 12-inch radius around the opening of the burrow. Such grazing was especially evident in areas where rabbit brush, Chrijsoihamnus nauseosus, occurred. Gophers appear to relish the above-ground parts of this plant as well as its roots, as was verified by the feeding of captives ( Table 2 ) . Gophers also harvested sweet vetch, Astragalus scopiilorum, and Indian rice grass, Oryzopsis hymenoicles, and aerial parts of these plants were found in tunnels. Such aerial parts were cut into lengths of six or seven inches before being taken below ground. Side tunnels of burrows often were packed with small pieces (one to two inches long) of roots and grass stems. These accumu- lations probably represent food caches that are stored for later use. All such caches filled with vegetation and soil were found within one or two feet of a burrow opening. Several cones and numerous nuts of pinyon pine, Vinus eduUs, were found in the cache of one gopher. 158 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. The cones had been opened and most of the nuts had been removed and eaten; the chewed coats of seeds remained in the tunnel. This was especially interesting because the nearest pinyon pine was about 30 feet from the opening of the burrow; the opening was also at that part of the tunnel nearest the woodland. Captive gophers soon die if they are not given succulent plants or roots to eat. On the other hand, captives gain weight and thrive on a diet of potatoes and rolled oats, supplemented with fresh green vegetation. Gophers probably do not produce much if any, meta- bolic water. Roots found in cheek pouches and in tunnels indicate that they prefer non-woody, succulent roots that can be eaten easily. Few woody roots were recovered from cheek pouches or from tun- nels. Captives chewed the softer parts of roots and stems, but rarely bothered with woody roots when other foods were available. All stomach contents of Thomomijs that I have seen always were green in color, indicating extensive foraging on aerial parts of plants. The fossorial mode of life permits Thomomys to avoid the prob- lems of thermo-regulation that would be attendant with living on the surface. Fossorial forms are known to ha\'e poor thermo-regula- tion and a generally low tolerance to high temperatures. The maintenance of water balance also can be a pressing problem facing species Hving in arid environments. Relative humidity is more con- stant in burrows than it is at the surface (Kennerly, 1964); thus living in subterranean tunnels permits gophers to avoid desiccation and the need for obtaining larger amounts of moisture to facilitate osmoregulation. The storage of roots and stems underground provides a source of moist vegetation for gophers. This would be advantageous to them in the hottest months of summer and during periods of drought when aerial parts of plants, and perhaps many root systems are reduced in moisture content. Thomomys hottae apparently is well adapted to life in arid environments because of its behavior, rather than because of its physiological adaptations. Thomomys hottae is coprophagic, and captives often were ob- served to eat feces. This was accomplished in such a way that it has not been possible to determine whether this species produces two kinds of droppings, as do rabbits. At any rate, captive in- dividuals produce copious droppings and, as would be expected, the caecum is large and probably contains bacteria that break down cellulose. Douglas — Pocket Gophers of Mesa Verde 159 Reproduction, Growth, and Development In Mesa Verde, reproduction in Thomomijs occurs only in spring. Pregnant females were taken in late April and early May; females with enlarged uteri were taken in April, August, and Sep- tember, indicating that reproducti\-e activity probably begins in March, or perhaps late in February. The gestation period for T. hottae is about 18 to 19 days (Schramm, 1961). Lactating females were taken in early May, but none of 31 females taken in August or September was lactating (Fig. 6). Four females had from two to four embryos each (average three). Two other females each had ^ 10 < Q > Q o Pregnant Q Lactating Q Enlarged Uterus JJ APRIL MAY ] Non- Reproductive P — T r1- , 1 AUG. SEPT. W 20- u Pt ^ kJ n 1- iO ' LlI h- n l—, u. 1-, o /o- ^ X 1- ^ , 1 2 ^ LU _J - 0 — APR. MAY AUG. NUMBER OF SEPT. INDIVIDUALS Fig. 6. Condition of reproductive organs of dissected gophers collected in Mesa Verde from 1965 through 1967. Reproductive condition of females (upper) in \arious months; size of testes of males (lower) collected in various months. 160 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. three placental scars. Howard and Childs (1959:295) reported an average litter size of 4.6 for T. h. meica from California. Young of the year appeared in traps in April, May, August, and September. Unfortunately, no gophers have been trapped in Mesa Verde earlier than April and none has been taken in June or July; the data on reproduction are therefore incomplete. Eight males taken in late April and early May of 1967 were in breeding condition. Howard and Childs (1959:300) separated kill- trapped individuals of T. botfae into three age classes by the size of the testes. Testes of animals less than five months of age were between one and 10 millimeters in length (average 4.5 mm.). Males nine months or older had testes 12 millimeters or longer. Figure 6 shows the length of testes in males taken in Mesa Verde in various months of the year. Testes of adults taken in spring were engorged, highly vascularized, and scrotal, whereas those of adults taken in August or September were flaccid, wrinkled, and less vasculariza- tion was present. Testes of young males were not apparent external- ly and it is difficult to sex such young animals without dissecting them. Figure 7 shows the distribution of sizes of males and females taken from Mesa Verde, and the months in which they were taken. Although the samples are somewhat limited, it is apparent that young of the year grow rapidly and attain adult size by autumn, when separation of young and adult individuals can best be accom- plished by examining reproductive tracts. Apparently, few females breed in the first year, whereas all individuals a year old or older evidence reproductive activity. This agrees with reports in the literature (Howard and Childs, 1959:302). Table 3 summarizes measurements taken on 122 specimens examined in this study. Measurements for young of the year ( young and subadult individuals ) are given separately from those of adults. Juveniles are those animals that are still in the nest, or that have Juvenal pelage. These individuals can be distinguished easily from adults, but seldom appear in traps. Young individuals are those that are moving about on their own, and those in which the juvenal pelage is being replaced. Subadults are those young of the year that have reached adult proportions but have not yet bred. Adults are those indixiduals sho\\'ing signs of reproductive activity. In some cases, young of the year may breed and thus would then be classified as adults, but breeding in the first season probably is an unusual occurrence in Mesa Verde. Douglas — Pocket Gophers of Mesa Verde 161 5 APRIL / / 0 Z ■ r- 1 1 ' CO 5 _J < Q > 0 MAY V I T 1 r / -■ / -a T 1 I r- Ll_ O on UJ QQ 0 AUGUST 10 5- SEPTEMBER MALES 7^ FEMALES / / ^/ * 1 r 1 1 ' ' 176 I7S- 185 186- 195 196- 205 206- 215 216- 225 226- 235 LENGTH IN MILLIMETERS 236- 245 246- 255 Fig. 7. Size distril:)ution of 63 male and 57 female pocket gophers taken in Mesa Verde National Park and vicinity. In young females the pubic symphysis is not fully absorbed, the nipples are not enlarged, and the uterus usually is not dilated nor does it show other evidence of breeding activity. Individuals meet- ing these criteria were considered to be young of the year, irrespec- tive of their external size or dimensions of the skull. Three young females taken in late April measured 177 to 197 millimeters in total length (average 187 mm.), indicating the rapid growth achieved by 162 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 3. — Measurements, in millimeters, of Thomomijs bottae. Adult in- dividuals WERE THOSE EXHIBITING EVIDENCE OF REPRODUCTIVE ACTIVITY; YOUNG INDIVIDUALS WERE THOSE JUVENILES AND YOUNG OF THE YEAR SHOWING NO REPRODUCTIVE ACTIVITY. MeAN, MAXIMUM AND MINIMUM ARE GIVEN IN THAT ORDER FOR EACH MEASUREMENT. 30 adult 28 young 37 adult 27 young Measurement females females males males Total length .. 211 201 220 203 240 220 250 225 185 175 187 174 Length of tail .- 57 57 62 60 66 71 79 83 42 48 48 50 Length of hind foot 29 28 29 29 32 30 35 33 26 24 27 25 Condylobasal length .. 37.4 35.8 39.3 35.5 40.6 38.5 44.9 39.9 34.1 32.0 34.4 30.8 Palatal length - 22.0 21.0 23.4 20.9 23.9 23.6 26.7 23.5 20.3 17.9 19.6 17.5 Length of nasal ._ 11.9 11.2 12.9 11.3 13.4 12.5 15.3 13.8 10.7 9.4 10.2 8.7 Zygomatic breadth .. 23.6 22.6 24.9 22.0 25.6 24.6 28.4 25.5 21.5 19.3 22.6 19.6 Mastoidal breadth . 19.4 19.1 20.3 18.6 20.9 20.1 23.0 21.0 18.0 15.9 16.8 16.3 Least interorbital lireadth - 6.3 6.3 6.1 6.3 6.8 6.8 6.9 6.8 5.6 5.7 5.3 5.8 Alveolar length of maxillary toothrow ..- 7.4 7.3 7.7 7.2 8.7 8.3 8.9 8.1 6.6 6.2 6.5 6.5 Length of mandible .. 25.3 24.4 26.9 24.6 28.6 27.3 31.8 27.5 22.9 20.1 22.4 21.2 Capacity of braincase (cc. ) 1.3 1.2 1.3 1.3 1.5 1.4 1.6 1.4 1.1 1.0 1.1 1.1 young individuals in the first several months of life. Twenty-three young females taken in August and September measured from 178 to 219 millimeters in total length (average 202), whereas 27 adult Douglas — Pocket Gophers of Mesa Verde 163 females had total lengths of 185 to 238 millimeters (average 212). It is apparent that most young individuals attain adult size quite rapidly. Individuals born early in the season may reach adult pro- portions by late spring and certainly do so by autumn. In young males the testes are mucJi smaller than those of males more than one year old (Howard and Childs, 1959:300). Thirty young of the year had testes between three and 10 millimeters in length (average 6.0), and total lengths from 187 to 226 millimeters (average 209). Nineteen adults had testes that measured 11 to 20 millimeters in length (average 15) and total lengths ranging from 187 to 250 (average 223). Youngman (1958:366) studied museum specimens of T. hottae from Colorado, and established three criteria for adulthood: ". . . (a) suture obliterated between supraoccipital and exoccipital, (b) suture at least partly obliterated between basisphenoid and basioccipital, (c) supraorbital crests not widely separated and al- most parallel. ..." I examined 26 skulls from young females, col- lected in the course of the present study, in order to see if these three criteria are applicable when reproductive condition is known. The skulls were from animals that were unquestionably young of the year. These individuals exhibited no internal or external evi- dence of reproductive activity, the pubic bar had not been resorbed, and they were among the smaller individuals taken. Females were used because their lack of reproductive activity can be determined with much more certainty than can that of males. Of the 26 young of the year, 16 met Youngman's first criterion (see above), 18 met the second criterion, and 12 met the third. Because of the rapid rate of growth in young and subadult in- dividuals, developmental characteristics of the skull may be mis- leading for the establishment of age groupings. I do not consider the above-listed criteria adequate for differentiating young of the year from adult individuals. When studying museum specimens, the investigator must establish arbitrary criteria for separating age groupings. At present there is little known about rates of growth in geomyids, as in other non-game species, and it would be vii'tually impossible for an investigator to assign accurate age groupings on the basis of skull dimensions alone, without having knowledge of the condition of reproductive organs, and in the case of females, the condition of pubic bones. Many investigators do not dissect female gophers, or if they do, the tendency seems to be to make no notation on the specimen label unless embryos are found. There is 164 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. more of a tendency to measure and record the size of testes. It is to be hoped that in the future investigators will record lack of embryos as well as their presence; information as to presence or absence of the pubic bar in females also should be recorded. Climatic Conditions Affecting Gophers at Park Point Climatic conditions were studied at Park Point, (S575 feet eleva- tion (see Fig. 8), the highest point in Mesa Verde, as part of an environment measurement program of the Wetherill Mesa Project. Fig. 8. View southward from Park Point, the highest elevation in Mesa Verde (8575 feet). Gophers lived on this ridge from 1961 to 1967 despite the rocky nature of the soil. As mentioned earlier, one of the largest colonies of pocket gophers in Mesa Verde occurs at Park Point. Thus the choice of this site for a weather station was indeed fortunate. The occurrence of gophers on this rocky ridge was first noticed when the weather station was installed. Gophers later were observed to pile mounds of soil in areas where, because of rocks, I had difficulty in obtaining soil samples at the six- and 12-inch depths. I was surprised to find a sizeable colony of gophers on this ridge where the soil was shallow and rocky and where vegetation, although not in short supply, Douglas — Pocket Gophers of Mesa Verde 165 seemed to require such an expenditure of effort for gophers to obtain. A standard U.S. Weather Bureau shelter was installed at this site in September of 1961 and instruments were run through December, 1963. Air temperatures and relative humidities were recorded by means of a Bendix hygrothermograph; soil temperatures were re- corded at depths of two, six, and 12 inches by a Kahl three-pen thermograph; and precipitation was measured by means of a standard Weather Bureau rain gauge. Soil moisture was determined gravimetric-ally at depths of two, six, and 12 inches about twice each month. Table 4 summarizes the climatic conditions at Park Point. Pre- cipitation at this site is the highest of that at any sites measured in the Mesa Verde. The higher parts of the Mesa Verde land mass are first to receive moisture from ephemeral storms that originate in the nearby La Plata Mountains. Therefore, the higher, northern ends of the mesas are more mesic than the southern ends, and winters are the more severe at the higher elevations. Park Point has the most severe climate of the Mesa Verde as far as cold, persistent snows, and frozen soils are concerned. The growing season at this site is shorter than that at lower elevations. The range of thermal tolerance of Thomomys hottae has not yet been studied, but it is apparent that this species escapes the high surface temperatures and the metabolic stresses that would result from living at such temperatures, by living six or more inches below the surface. Gophers are active in the winter at Park Point, and in the spring evidence of winter digging is apparent as tubes of soil lying on the surface. In winter, soil temperatures at all levels varied only a few degrees on either side of freezing. Soil temperatures at the lower levels were found to be only slightly above freezing in March when, it is thought, most of the young are born. There is little air move- ment in tunnels of TJiomomys; therefore, temperatures in tunnels are the same as those in soils at the same depths (Howard and Ghilds, 1959:332; Wilks, 1963:272; Kennerly, 1964:408). The tubes of soil evident on the surface in spring represent tun- nels in the snow that were filled with soil. There would seem to be little need for gophers to move soil in order to feed on surface vegetation in the winter, because they could, and do, tunnel in the snow at the surface ( see Marshall, 1941 ) . Some of the roots prob- 166 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 4. — Soil temperatures at depths of two, six, and 12 inches and PRECIPITATION RECORDED AT PaRK PoINT, 8500 FT., MeSA VeRDE NATIONAL Park. The range represents extreme temperatures for each month; MEAN temperatures REPRESENT A MONTHLY AVERAGE OF DAILY MAXIMUM AND MINIMUM READINGS. An ASTERISK INDICATES INCOMPLETE DATA. Two inches Six in( :hes 12 inches Precipitation Date Range Mean Range Mean Range Me.in in inches 1962° April 29-72 51.0 36-59 48.5 39-52 46.5 0.39 1962 May 33-79 55.7 39-67 53.0 40-59 50.9 0.93 1962 June 42-103 71.6 47-81 66.4 49-72 62.7 1.03 1962 July 55-104 78.7 63-83 72.9 64-74 69.7 2.02 1962 August 52-105 77.9 60-85 73.2 63-76 70.2 1.97 1962 September 38-96 66.3 45-77 63.4 48-69 61.8 2.13 1962 October 34-76 51.7 38-64 50.2 41-56 48.8 2.94 1962 November 30-64 40.3 31-54 39.9 32-48 .39.4 1.50 1962 December 24-41 29.8 26-35 30.4 26-33 30.2 0.90 1963 January 23-31 27.5 2,5-32 29.1 2.5-34 29.9 1..30 1963 Feliruary 26-34 30.4 28-35 31.4 28-35 .32.1 1.20 1963 March 24-64 33.2 27-51 32.6 28-45 33.0 1.00 1963 April 28-73 47.1 32-59 45.2 35-53 44.1 0..55 1963 May 42-95 67.5 46-76 63.1 48-68 60.6 0.16 1963 June 45-111 76.8 55-89 71.2 59-79 69.1 0.07 1963 July 55-110 81.8 61-90 76.7 66-81 75.3 1.97 1963 August 54-110 74.5 58-87 70.7 63-80 70.3 7.62 1963 September 49-99 72.9 56-79 67.8 61-71 66.6 0.45 1963 October 36-100 64.5 43-77 .59.9 49-70 .59.8 2.70 1963 November 24-66 39.2 32-54 38.8 34-49 40.5 1.04 1963° December 24-44 33.6 29-36 32.7 32-36 34.6 0.75 1964 April 27-70 43.4 32-55 40.6 35-48 40.0 1964 May 31-92 60.0 35-74 56.0 38-67 54.0 1964 June 40-107 75.0 49-82 68.0 52-75 66.0 1964 July 53-112 82.0 61-89 75.0 65-80 74.0 1964° August 47-104 74.0 58-83 70.0 63-76 69.0 ably are dug and eaten below the surface, even though the first few inches at the surface are frozen. Mounds could not be piled easily in the winter due to the pressure of overlying snow, and tunnels may be dug in the snow to accept this excess dirt. The number of surface tubes indicate that gophers do not dig soil extensively throughout the winter. Soil for surface tubes must come from below the surface, for I have found no evidence of surface gouging that would be expected if gophers were digging shallow trenches to obtain roots at the surface, and then were filling the snow tunnels behind them. I think that food caches and surface feeding are the most likely sources of food in winter months when the ground is frozen. It seems likely that tubes of soil may represent that removed during tunnel cleaning, especially by females preparing to bear young. Gophers in Mesa Verde have two periods of increased mound production. One period is apparent late in the autumn, especially in Douglas — Pocket Gophers of Mesa Verde 167 October and November, prior to the onset of cold weather. The other period is in the spring after the ground thaws. In Mesa Verde the ground thaws and the kinds of animals that hibernate begin to appear above ground by about the first of April. The only significant reduction in mound building activity occurs in June and July, when surface temperatures are high. It is not known whether Thomomijs aestivates during part of the summer, although Howard and Childs ( 1959) have suggested this possibility. In Mesa Verde there is some mound building throughout all months of spring, summer, and autumn. Mound building has been thought to be associated with an in- crease in soil moisture (Miller, 1948). Kennerly (1964) has shown that the period of increased mound building by Geomys begins before and subsides later than the period of sustained high soil moisture. He suggested that a basic biologic rhythm is involved and that factors other than soil moisture influence mound building. In Mesa Verde, the months generally having the most precipita- tion are July, August, and February. Although the increase of mound building in the spring appears to coincide with an increase in soil moisture, the autumn period of activity comes after the period of increased soil moisture. Parasitism Trap-killed gophers were placed in a plastic bag immediately upon removal from their burrows. Ectoparasites were killed by placing a piece of cotton soaked in carbon tetrachloride in the closed bag with the gopher. After several minutes the parasites could be brushed from the fur and collected on a piece of paper. Endopara- sites were recovered from stomachs and intestines, were stored in 70 per cent ethanol, and were later sent to experts for identification. Gophers in Mesa Verde are heavily parasitized by fleas. Several individuals had more than a dozen fleas each; the most heavily parasitized individual, an old male, had 53 fleas of two species. This male was captured alixe, and it was apparent from his frequent scratching that the fleas caused a great deal of discomfort. Only one tick, an adult Dermacentor andersoni, was found on a gopher collected in this study. The tick was found on the cheek, in the middle of a circle about one half inch in diameter where the fur had been rubbed off. Such aggravation by parasites may be linked to the irregular molting patterns seen in Tlwmomijs. 168 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. It was surprising to find gophers parasitized by larvae of botflies, because these flies lay eggs on the fur of animals, an activity that obviously occurs above ground. The lar\'ae found in gophers appear to me to be identical in appearance with those of Cuterehra cyanella Jones found in Peromyscus from Mesa Verde (Douglas, 1967a). Judging from larvae found under the skin and from open exit holes made by larvae, infected gophers have from one to three larvae each. The incidence of infestation was highest in September. Some larvae were found in August, but none was observed in gophers collected in spring. In summary, parasites presently known from Thomomys hottae from Mesa Verde are as follows: Dermacentor andersoni (Acarina, Ixodidae); Cuterehra cf. cyanella ( Diptera, Cuterebridae ) ; Trichu- ris fossor (Nematoda); DactylopsyUa (Foxella) ignota, Dactylopsylla rara, and DactylopsyUa sp. (Siphonaptera). In addition, specimens of Cestoda, Mallophaga, and mites currently are being studied and will be reported elsewhere. Predation Coyotes are the major carnivores in Mesa Verde that are known to prey upon pocket gophers (Howard and Childs, 1959:337; Wilks, 1963:277). Foxes also are common in the area, but appear to rely more upon berries and lizards than do coyotes. I examined a total of 114 coyote scats that were collected at Mesa Verde each month from September, 1963, through August, 1964. Numerous rodents, but no pocket gophers, were present in the 253 food items repre- sented (Douglas, 1967a). Sixteen scats of foxes contained several rodents, but no gophers. Bobcats also are present in Mesa Verde, but scats of bobcats were seen only rarely, and none has been analyzed. Hawks, owls, and eagles live in Mesa Verde. Red-tailed hawks were seen frequently on the burned area on the northern end of Wetherill Mesa. I haxe not been successful in locating occupied hawk or owl nests there. Howard and Childs (1959:337) reported that gophers comprise 7.4 per cent of the diet of red-tailed hawks, and 71.4 per cent of the diet of barn owls at the San Joaquin Experi- mental Range in California. It seems likely that owls may be a significant predator on gophers in Mesa Verde. There are two species of snakes, the gopher snake, Pituophis melanoleucus, and the rattlesnake, Crotalus viridis, in Mesa Verde that could be considered as potential predators on gophers ( Doug- Douglas — Pocket Gophers of Mesa Verde 169 las, 1966). Of the two, the gopher snake is more abundant. I have collected and examined numerous gopher snakes and other snakes in Mesa Verde, but none contained gopher remains. Gopher remains were not present in the 130 scats of carnivores that I examined, and none was present in 35 scats of coyotes from the area examined by Anderson ( 1961 ) . Therefore, it seems unlikely that carnivores exert much influence on population dynamics of gophers in Mesa Verde. Anomalies The following skeletal and dental anomalies were noted in specimens examined. The lower jaw of an adult male (CLD SIO) has a deformed coronoid process, composed of two parts. The ventral part is of normal size in width and depth, but the dorsal part is slender and abnormally close to the articular process. The coronoid process appears to have been broken, then to have ankylosed where the halves touched. The dorsal part of the process barely clears the squamosal when the jaws are articulated in occlusal position with the skull. Another adult male (KU 75977), taken on November 10, 1957, in Prater Canvon, 7500 ft., bv T. R. Alcorn, has several anomalies of the skull. A tumerous growth had deformed the zygomatic plate of the right maxilla, and also involved smaller bones in the area. The right zygomatic plate is abnormally thick, antero-posteriorly; a bulge of bone protrudes from the posterior part of the plate into the orbit. There is a small hole in the maxilla just anterior to the lacrimal. A wormian bone is present at the junction of the right maxilla, lacrimal, and frontal bones. The right jugal is abnormally short and thick, and the zygomatic arch is somewhat displaced medially because of the tumerous growth on the zygomatic plate and a bending of the rostrum to the right. The posterior, ventral margins of the premaxillae appear to have broken, owing to the torsion of the rostrum. A suture occurs in the left premaxilla in line ^\'ith the posterior border of the nasals, and a suture occurs some- what posterior to this in the right premaxilla. The torsion of the rostrum has resulted in malocclusion of the upper and lower incisors, but the maxillary and mandibular toothrows appear to be normal. A young female (CLD 959) has an unusual dental anomaly. The anterior prism of each lower premolar (p4) is unworn and 170 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. projects dorsally two and three millimeters above the posterior prisms of the respective premolars. The reason for this anomaly appears to be related to the mobility of the jaws. The glenoid fossa in gophers is several millimeters in length and is parallel to the long axis of the skull. This arrangement facilitates propalinal chew- ing with the cheekteeth, and allows forward movement of the jaws such that the incisors occlude and can be used when the cheekteeth are disengaged. Normally, when the lower jaws are at their pos- teriormost position and the cheekteeth are occluding, the anterior prism of each lower premolar lies in line with the posterior prism of each upper premolar. In this specimen the jaws cannot mo\'e far enough posteriorly for such an overbite to occur. The mobility of the lower jaws is restricted because the distance between rami is not great enough at their posterior ends. Thus, the articular processes bind against the medial sides of the glenoid fossae and against the bullae, before reaching their posteriormost position in the fossa. As a result, the anterior prisms on the lower premolars do not occlude, and remain unworn. Discussion In Mesa Verde, pocket gophers live in soils having less than 32 per cent clay and varying amounts of sand and silt. Ten of 18 samples of soil from areas inhabited by gophers contained more silt than sand, whereas the other eight contained more sand than silt. It seems likely that the percentage of clay affects the ability of gophers to use soils more than do varying amounts of silt and sand. Downhower and Hall (1966) found Geomijs in Kansas Hving only in soils having less than 30 per cent clay and more than 40 per cent sand. Attempts by these authors to introduce pocket gophers at places where none lived were least successful where soils had a relatively high clay content. Although the percentage of clay in most of the soils in Mesa Verde was low, it was sufficiently high in most localities to make the setting of traps difficult when the soil was dry. Soils at various localities on the mesa were dry and hard during much of the sum- mer, whereas those in the bottoms of canyons remained friable throughout the year. The largest sites of concentration of gophers in Mesa Verde occurred in areas having deep soils. Nevertheless, gophers were taken from rocky areas and from places in the woodland where soils Douglas — Pocket Goppiers of Mesa Verde 171 were eight inches or less in depth. In such cases, deeper soils gen- erally were within part of the individual's range. When a gopher was taken from a shallow burrow system, it invariably was a young indixidual. Burrow systems of adults were at varying depths below the surface, depending upon the depth of soil and amount of rock in the habitat. In deep sandy soils, main tunnels of adults generally were eight to 12 inches below the surface; feeding tunnels were shallower. Gophers live in various vegetational associations in Mesa Verde. In some places grasses are the most abundant plants, but in most places shrubs and various herbaceous species also occur in the ground cover. Gophers eat a variety of roots and aerial parts of plants, as was determined from feeding experiments with captives and by inspecting contents of caches and cheek pouches of gophers. Most localities at which gophers have been taken in Mesa Verde are on the northern half of the park, at the higher elevations. Gophers are most abundant along the North Rim and in the deep soils of canyons. In general, large colonies do not occur on the mesas at elevations of less than 7000 feet; the lowest canyon eleva- tions at which gophers were taken was at 6200 feet along the Mancos River. The occurrence of a large colony of gophers on the southern end of Moccasin Mesa is somewhat unusual. Gophers were not found in sandy drainages on the southern ends of other mesas in the park. I think that the deepness of the soil in the meadow on Moccasin Mesa and the persistent moisture of lower depths helps to explain the ability of gophers to live there. This soil moisture is reflected also in the abundance of grasses and herbaceous species in the ground cover; a dense ground cover is not common at lower eleva- tions on the mesas. Apparently the soil in the meadow is deep enough over the underlying bedrock to retain runoff moisture effectively. Cactus is thought to be an important source of moisture for gophers, especially on the southern end of Moccasin Mesa. Less precipitation occurs at the lower elevations on the southern end of Mesa Verde, thus soils and plants tend to dry out earlier in the summer at these elevations than at higher, more mesic elevations on the north. The roots of cacti were cropped severely during summer months by gophers on Moccasin Mesa. Such a reliance upon cacti was not evident in habitats of higher elevations in the park. 172 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Captive gophers were found to prefer soft, fleshy roots to hard, woody roots. Roots found in food caches and in cheek pouches of gophers were mostly fleshy kinds. Grasses, bushes, and shrubs have numerous soft fleshy roots that apparently can be cropped repeat- edly. Plants having only one major tap root, as do many herbaceous species, can be eliminated rather quickly by having their roots cropped. It is thought that Thomomijs influences the succession of vegetation by a series of events. Initially the soil is disturbed by mound building, thereby providing a seed bed for early successional plants such as globe mallow and other weedy species. Gophers eat roots of the weedy plants that have become established and the evidence indicates that many plants are killed in the process. In about two years time, the earliest-built mounds have become obliterated. Because the disturbed area usually is small, invasion by plants is rapid. The gopher thus changes the habitat temporarily insofar as the vegetation is concerned. On the other hand, gophers turn over large quantities of soil, and their burrows permit percola- tion of moisture to lower depths; storage of roots, and deposition of fecal material also raises the organic content of the soil. The two periods of increased activity in mound building, occur- ring in spring and in late autumn, appear to be related, respectively, to increasing and decreasing temperatures at the 12-inch depth. The causality of this relationship can only be inferred. Gophers also bear young in spring during the period of soil warming, although the earliest breeders must bear young when the soil is still rather cold. Thomomijs apparently forages above ground more extensively than has been supposed. Pine cones found in a food cache suggest that at least one individual may have foraged at a distance of about 30 feet from its burrow. Shrubs, especially rabbit brush, occurring within several feet of fresh mounds showed evidence of browsing. It is assumed that the browsing was done by gophers, owing to the proximity of the shrubs to the mounds and because of the fondness of captives for stems of this shrub. Various investigators have remarked that gophers, when released near their burrow, do not alwavs seem to be aware of where to enter their tunnels, and often dig new holes. This may be due to in- dividuals being released in daylight; gophers are known to forage above ground at night, and occasionally in the daytime when the sky is overcast. Evidence indicates that gophers forage around the Douglas — Pocket Gophers of Mesa Verde 173 openings of their burrows, and that they move about on the surface and perhaps range for some distance from the openirigs. Remains of Tlwmomys have been found in owl pellets (Howard and Child, 1959) and these gophers also have been taken in snap traps set for mice (WilHams, 1955:227). Larvae of bot flies were found in gophers taken in Mesa Verde, indicating that they spend enough time above ground for Hies to lay eggs on their fur. The present lack of knowledge about how to accurately deter- mine the age of gophers from skeletal characteristics presents a per- plexing problem. Young of the year were found to attain adult size at a rapid rate, and animals several months old could not be differ- entiated from adults on the basis of skeletal or bodily dimensions. Examination of reproductix'e organs allows separation of young of the year from adults and this is of some value in studying popula- tions. It would be invaluable to future studies of gopher populations if an accurate method of estimating chronological age could be found. Studies presently are being conducted toward this objective and these will be reported elsewhere. Relationship of Gophers to Archeological Sites Mesa Verde National Park was formed to protect dwellings of prehistoric Indians who once lived in the area. Park officials are responsible for protecting not only these prehistoric ruins, but also the flora and fauna. Burrowing rodents occasionally cause damage to important archeological sites, and although gophers are less of a problem than rock squirrels, chipmunks, or badgers, they can and do damage sites by burrowing through such things as trash mounds, which would be far more valuable if undisturbed. In Mesa Verde Site 786, a gopher skeleton was recovered from a timnel that ended on the floor of a kiva, 72 inches below the surface of the ground (Arthur Rohn, personal com- munication). The digging of a tunnel to this deptli undoubtedly was facilitated by the friable nature of the fill in the kiva. Such burrows easily can allow small artifacts to become juxtaposed in the occupational strata, thereby render- ing interpretation difficult, if not impossible. In order to maintain the integrity of archeological sites in Mesa Verde and elsewhere, gophers and other burrowing rodents should be removed as soon as possible after they are noticed in such places. Macabee traps are recommended for pocket gophers and are most effective when used in pairs — one trap being set in each direction in a main underground tunnel. Gophers are important members of the faunal assemblage, however, and should be removed only when they are distiul)ing archeological sites or underground cables. Acknowledgments These studies were begun while I was Biologist for the Wetherill Mesa Archeological Project. This and other studies would not have been possible without the support and encouragement of Dr. Douglas Osliorne, Long Beach 174 Misc. Publ. 51, Uxw. Kansas Mus. Nat. Hist. State College, formerly director of the Wetherill Project. I am grateful to Robert R. Patterson, The University of Kansas, who took his vacation time to assist me in the field in 1963 and 1965. Mr. Chester A. Thomas, formerly Sviperintendent, and Mrs. Jean Pinkley, formerly Chief of Interpretation at Mesa Verde National Park, assisted me by arranging for my NPS collaborator- ship and collecting permits. Stanley Welsh, Brigham Young University, and James A. Erdman, United States Geological Survey, Denver, proxided identi- fications for numerous species of plants. Mrs. Marilyn A. Colyer, Mancos, Colorado, assisted me in analyzing vegetation in \arious habitats. I am indebted to John Ubelaker for identifying endoparasites and to Cluff Hopla for identify- ing fleas from numerous gophers. The opportunity to work in the field in 1967 was made possible by a grant-in-aid from the Society of The Sigma Xi. The Wetherill Mesa Project was an interdisciplinary program of the National Park Service to which the National Geographic Society contributed generously. I am indebted to the Society for a major share of the support that resulted in this report. This paper is contribution no. 48 of the Wetherill Mesa Project. Literature Cited Anderson, S. 1961. Mammals of Mesa Verde National Park, Colorado. Univ. Kansas Publ., Mus. Nat. Hist., 14:29-67, 2 pis., 3 figs. Arrhenius, G., and E. Bonatti 1965. The Mesa Verde loess. Amer. Antiquity, 31 (part 2):92-100, 6 figs. BouYOucos, G. J. 1962. Hydrometer method improved for making particle size analyses of soils. Agronomy Jour., 54:464-465. Douglas, C. L. 1963. Apache pocket mouse found in Mesa Verde National Park, Colorado. Southwestern Nat., 8:173. 1966. Amphibians and reptiles of Mesa Verde National Park, Colorado. Univ. Kansas Publ., Mus. Nat. Hist., 15:711-744, pis. 37-38, 6 figs. 1967a. Comparatixe ecology f)f pinyon mice and deer mice in Mesa Verde National Park, Colorado. Ph.D. dissertation, Uni\'. Kansas, Law- rence, 209 pp. 1967b. New records of mammals from Mesa Verde National Park, Colorado. Jour. Mamm., 48:322-323. Douglas, C. L., and J. A. Erdman 1967. Development of terminal buds in pinyon pine and Douglas-fir trees. Pearce-Sellards Series, Texas Mem. Mus., 8:1-19, 5 figs. DowNHOWER, J. F., and E. R. Hall 1966. The pocket gopher in Kansas. Misc. Publ. Mus. Nat. Hist., Univ. Kansas, 44:1-32, 8 figs. Erdman, J. A. 1962. Ecology of the pinyon-juniper woodland of Wetherill Mesa, Mesa Verde National Park, Colorado. M.A. thesis, Univ. Colorado, Boulder. Erdman, J. A., W. A. Weber, and J. M. Tucker 1962. Querciis ajoensis in Colorado. Southwestern Nat., 7:269-270. Fritts, H. C, D. G. Smith, and M. A. Stokes 1965. The biological model for paleoclimatic interpretation of Mesa Verde tree-ring series. Amer. Antiquity, 31 (part 2):101-121, 10 figs. Howard, W. E., and H. E. Childs, Jr. 1959. Ecology of pocket gophers with emphasis on Thomomys bottae mewa. Hilgardia, 29:277-358, 40 figs. Douglas — Pocket Gophers of Mesa Verde 175 Kenxerly, T. E., Jr. 1964. Microenvironniental conditions of the pocket gopher l)mr()\v. Texas Jour. Sci., 16:395-441, 16 figs. Marshall, \V. H. 1941. Thomomys as hurrowers in the snow. Jour. Manim., 22:196-197, 2 figs. Miller, M. A. 1948. Seasonal trends in burrowing of pocket gophers (Thomomys). Jour. Manim., 29:38-44, 1 pi., 2 figs. Schramm, P. 1961. Copulation and gestation in the pocket gopher. Jour. Mamm., 42:167-170. Welsh, S. L., and J. A. Erdman 1964. Annotated checklist of the plants of Mesa Verde, Colorado. Brigham Young Univ. Sci. Bull., Biol. Ser., 4:1-32. WiLKS, B. J. 196.3. Some aspects of the ecology and population dynamics of the pocket gopher (Geomy.s btirsarius) in southern Texas. Texas Jour. Sci., 15:241-283, 5 figs. Williams, O. 1955. Distribution of mice and shrews in a Colorado montane forest. Jour. Mamm., 36:221-231, 1 pi., 1 fig. YOUN'GMAX, P. M. 1958. Ceographic variation in the pocket gopher, Thomomys bottae, in Colorado. Univ. Kansas Publ., Mus. Nat. Hist., 9:363-384, 7 figs. COTTON RATS OF THE SIGMODON FULVIVENTER GROUP BY RoLLiN H. Baicer Cotton rats of the genus Si^modon are dominant grass-eating and runway-making rodents in most grassy habitats of south tem- perate and tropieal North and Middle America. In this region, cotton rats play a role somewhat similar to that of voles of the genus Microtiis in north temperate and boreal parts of the continent. The genus is known from late Pliocene deposits of North America; one present-day species, S. luspidtis, is recorded from as far back as Sangamon times in the late Pleistocene. Today, rodents of this genus are widely distributed (see Fig. 1) from southern United States (north to 40° N latitude at the Kansas-Nebraska border) southward to coastal Peru (south to about 8° S latitude). Cotton rats are at home at altitudes ranging from sea level in coastal marshes to more than 3200 meters in the highlands of the Trans-Mexican Volcanic Belt. Ecologically, they are associated with grasses — which may be almost pure stands of perennial bunch grasses, mixed grasses and herbs, or mixed grasses and shrub growth — in a variety of habitats and climates in both xeric areas (where annual rainfall may be no more than 100 millimeters) and mesic situations (where annual rainfall may be more than 500 millimeters ) . Cotton rats have been known to science since 1825, when Say and Ord described Sigtiwdon Jiispidus from Florida. Descriptions of cotton rats from other localities appeared in the literature in the middle and late 1800's, and in 1902 Vernon Bailey reviewed the specific status of North American cotton rats and established the two presently recognized groups: the semi-naked-tailed S. Jiispidus and the hairy-tailed members of the S. fidviventer group. Bailey's find- ings and later taxonomic accounts, mostly by Nelson and Goldman and by Goodwin, form the basis for the synopsis found in Hall and Kelson (1959:671-679). According to the latter, the fidviventer group contains 12 species from widely-scattered locations in and along the Cordillera from Arizona, New Mexico, and Texas, south to the Mexican state of Oaxaca. It is the purpose of this report to review and revise this present taxonomic arrangement in light of (177) 178 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 1. Geographic distriliution of cotton rats. 1. Sigmodon hispidus. 2. Sig- modon fulviventer group. additional field and museum studies that have added to our knowl- edge of the distribution, ecology and systematics of the S. fulviventer group. Specimens examined are listed in the accounts of each taxa discussed. The number from each locality is noted, using abbreviations for the museums listed below to indicate where specimens are on deposit. I am grateful to the persons whose names appear below for allowing me the privilege of examining the specimens: (AM) American Museum of Natural History, G. G. Goodwin, R. G. Van Gelder, and S. Anderson; (CAS) California Academy of Sciences, R. T. Orr; (DMNH) Dallas Museum of Natural History, F. W. Miller; (FM) Field Museum of Natural History, P. Hershkovitz; (KU) University of Kansas, Museum of Natural History, E. R. Hall and J. K. Jones, Jr.; (LA) Los Angeles County Museum, K. Stager and C. A. McLaughlin; (LSU) Louisiana State University, Museum of Zoology, G. H. Lowery, Jr.; (MSU) Michigan State Baker — Sigmodon fulviventer Group 179 UniNersity, The Museum, R. H. Baker; (MVZ) Uuiveisity of California, Museum of Vertebrate Zoology, S. B. Benson and W. Z. Liclicker; ( OC ) Occi- dental College, J. W. Hardy; (TCWC) Texas Cooperative Wildlife Collection, Texas A&M Uni\ersity, W. B. Davis; (TT) Texas Technological College, R. L. Packard; (UI) University of Illinois, Museum of Natural History, D. F. Hoflmeister; (UM) University of Michigan, Museum of Zoology, W. H. Burt and E. T. Hooper; (UNAM) Instituto de Biologia, B. Villa-R.; (US) U.S. National Museum including Biological Sur\eys Collection, R. H. Manville and C. O. Handley, Jr. Field data and specimens (preserved or brought liack alive) have been obtained by summer expeditions from The Museiuu at Michigan State Univer- sity, beginning in 1957. Parties, headed by the author, \ isited known collecting sites for \arious species of cotton rats and also other likely places located geographically bet\veen these localities. Collecting was accomplished each summer from 1957 through 1967, except for 1962. Funds to assist in defraying costs of field work have geen generously provided l)y the MSU Development Fund, private donors Mrs. E. R. Warren and Mr. Russell Jameson, and the National Science Foundation (GB 2227). In the course of field work 25 per- sons, including long-time associate Dr. Robert G. Webb, accompanied me and must be recognized as important contributors to the success of the expeditions. These persons, most of them at the time advanced students in biology at Michigan State University, are Bruce R. Baker, Larry P. Bowdre, Daniel E. Boyle, Bernard J. Cripps, Peter L. Dalby, Julian P. Donahue, Leslie C. Drew, James J. Drake, Rol:)ert L. Fleming, William C. Gasaway, John Keever Greer, John J. Grost II, James R. Koschmann, David E. Mohrhardt, Michael K. Peter- sen, Carleton J. Phillips, Rudolph Scheibner, Henry L. Short, Charles E. Smith, Thomas Struhsaker, Donald F. Switzenberg, Charles L. Warner, Jr., Daniel Womochel, Robert G. Webb, and Frances E. Welling. I am grateful to the many persons in Mexico who were cooperative, offered advice, or allowed our field parties to \isit their properties, especially to Dr. Rodolfo Hernandez Corzo, Direccion General de la Fauna Silvestre, for granting scientific study permits. As always, I have depended to a great degree on the council of my good friend Dr. Bernardo Villa-R., whose vast knowledge of Mexican mammals is readily and generously shared with others. I acknowledge the help of Dr. John Beaman in identifying plants and Dr. Richard B. Loomis and Dr. Robert Traub for identifying ectoparasites. Finally, I dedicate this modest report to a truly great advisor and friend. Professor E. Raymond Hall, with whom I have spent many years of pleasant association and to whom American mammalogy owes so much for his steadfast determination to under- stand fully speciation in North American mammals. All measurements in this report are given in the metric system. Capitalized color terms are those of Ridgway (1912). Those localities printed in Roman type in the lists of specimens examined or of other records are recorded on the distribution maps as either solid circles ( specimens examined ) or as solid squares (other records). Localities printed in Italic type are not mapped be- cause of their proximity to other places that are mapped. All localities are arranged in the lists from north to south. Measurements of animals of the two sexes are included together since sexual dimorphism in the dimensions used was found to be negligible, although Chipman (1965) noted significant differ- 180 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. ences between sexes in weight and length of head and body in S. hispidus from Louisiana. Unless otherwise credited, all photographs were taken by the author. Determixatiox of Age in Cottox Rats Characteristics of the several species of cotton rats were determined by both gross and microscopic examinations. The selecting of comparati\e age-classes offered a prolilem because series of museum specimens include mostly young individuals. This is probably because most of them have been caught in museum special traps, which are not satisfactory for taking animals larger than 60-80 grams. Experience shows that the small- to medium-sized animals also make up a major segment of the trappable cotton rat population, especially in the period of greatest breeding activity in the warm months of the year, during which time most collecting parties are active. Cotton rats of each species, born and reared in captivity in the MSU Museum Live Animal Colony, were killed at intervals and measured. Growth curves, which level out at 250-300 days, are shown in Figures 2 and 3 (see also Hoffmeister, 1963, and Chipman, 1965). In laboratory-raised animals, females produced offspring at 87 days 190 100 200 300 400 180- 70 60 50, 500 600 S. fulwiventer 5. alleni S. leucotis S. ochrogngthu s _ 100 200 300 400 500 AGE IN DAYS 600 190 180 170 160 150 140 130 120 110 100 90 80 60 50 Fig. 2. Growth as judged by length of head and body in cotton rats of the Sigmodon fulvivei^ter group. Data from laboratory born and reared animals, the exact ages of which were known at death. Baker — Sigmodon fulviventer Group 181 37.5 3S.0 )5.0 100 -1— 200 300 400 SOO 600 — T" S. fulviventer S. glleni S. leucotis S. ochrognothus 37.5 35.0 32.5 30.0 27.5 22.5 20.0 17.5 - 18.0 100 200 300 AGE IN 400 DAYS 500 600 Fig. 3. of the Crania] fiiowth as judged by condylopremaxillary length in cotton rat.s Sif!.mod()n fulviventer group. Data from laboratory born and reared animals, the exact ages of which were known at death. (S. alleni), 77 days (S. fulviventer), and 71 days (S. hispidus and S. ochrognathus) and would have mated approximately 35 days earlier. Cotton rats (S. hispidus) in the wild are known to breed at 40-50 days of age (Odum, 1955). It is suspected then that the "normal" life span in natme is no more than six months (Meyer and Meyer, 1944, and Odum, 1955). This would mean that the trap- pable population would include few truly "full-grown" adult animals (at least 250 days old) and would help account for the scarcity of such animals in population samples preserved in museum collections. Study specimens of colony-raised animals purposely killed at 100 days and at 200 days were compared with wild-taken specimens with similar age charac- teristics. It was concluded that a cotton rat less than 75 days old is a juvenile, between 75 and 200 days old is a young adult, between 200 and 300 days old is an adult, and more than 300 days old is an old adult. A detailed study of the characteristics of aging, pelage development, and breeding habits will appear in a later report. Evolution in Recent Species Grass-eating as an Isolating Mechanism Probably an important factor in speciation in cotton rats has been the inabihty of different species to Hve together in the same habitat. On the few occasions when two species ha^'e been collected within the same grassy area, one has been common (seemingly dominant) 182 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. and the other rare. Field observations lead me to suspect that the local distribution of individual species has fluctuated owing to this competition in changing environments, especially due in the past century to various land-use practices by man, including clearing and lumbering, grazing of livestock, and cultivation. This activity has caused environmental changes that have favored one species o\'er another. Thus, in Michoacan, S. hispidus li^'es in undisturbed bunch grass (sacaton), whereas S. ciUeni lives nearby in heavily-grazed, brushy, fallow fields. The general negative interspecific reaction of species of cotton rats is not unique but seems typical as well of other grass-eating, runway-making rodents, notably \'oles of the genus Micwtus ( Find- ley, 1954; Anderson, 1959; Findley and Jones, 1962). In the Mexican highlands, cotton rats, M. mexicanus, and Neoiomodon alstoni (Davis and Follansbee, 1945) seem to avoid habitats occupied by the others. This relationship can be found also in such places as Kansas, where the aggressive S. hispidus probably is replacing M. ochrogaster, appearing to have accomplished this already in parts of Louisiana, Texas, and Oklahoma. In short, any given grassy habitat may harbor only one (or one dominant) species of grass-eating, runway-making rodent, but seed-eating species (included in such genera as Peromysciis, Reitlvodonfomys, Baiomijs, Liomys, Perogna- tJius) appear to experience little evident incompatibility in their own group or with the grass-eater, whose runways they use seem- ingly without restraint. That we find several seed-eating rodents but only one grass- eating rodent in a given grassy habitat may be because each seed- eater is adapted to a "smaller" segment of the environment (and thus allows space for se\'eral species) than is the grass-eater, whose habitat requirements may be too "broad" to allow for close neighbors with similar food habits. Species segregation and replacement, then, can be an important factor in evolution in Sigmodon. Ancestry Cotton rats are presumed to be of Neotropical origin, and prob- ably arose in early or middle Pliocene from a yet unknown, grass- eating cricetine ancestor. This ancestor probably had a four-rooted first lower molar (C. W. Hibbard, personal communication) and may have developed as a progressive oftslioot of the main line of phyllotine rodent origin ( Hershkovitz, 1962:23). It is suspected that cotton rats evohed in a Middle American pastoral habitat, although Hershkovitz (1966) believes it to be South American. Since the Baker — Sigmodon fulviventer Group 183 ^- hispidus ^ ^ S. hispidus S. fulviventer Sinaloa Durango Zacatecas Fig. 4. Distribution of species of Sigmodon along an east-west transect in northwestern Mexico between 23° 30' N and 24° 30' N. first terrestrial rodent en\'ironments to become established on the Panamanian land bridge after its emergence in late Pliocene were undoubtedly a series of grassland successions leading ultimately to savannas and forests, cotton rats could have easily moved southeast- ward to populate coastal parts of northern South America where they occur today ( see Fig. 1 ) . However, unlike other cricetines such as the rice rats (genus Oryzomys), cotton rats appeared unable to spread southward in South America to reach such likely habitats as the Argentine Pampas. Perhaps cotton rats (for which no South American fossils are known) arri\'ed later than rice rats and faced well-entrenched competitors or were blocked by encroaching in- terior and coastal forests in northern South America. In North America grasslands, which had their beginnings in the late Miocene and their great development in the Pliocene, extended southward into what is now Mexico and offered a broad avenue to northward movements of cotton rats (see Cohn, 1965:138-139). Throughout the Pleistocene this area was subjected to alternating mild and cool periods, and to aridity (Dillon, 1956:173) and subhumid conditions ( Hibbard, 1960 ) . Even so, early cotton rats, if possessed of some of the same ubiquitious characteristics as their modern counterparts, should have had no difficulty surviving such changes from the warm climate of their Neotropical home. The genus is first reported from the Blancan of the late Pliocene (Hibbard, 1960:17) with the modern species, S. hispidus, known 184 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. from what is now Texas as early as Sangamon times (third inter- glacial) in the Pleistocene (Moore Pit local fauna, Slaughter, 1966: 90). From the south-central United States, S. Jiispidus was presumed to have been displaced southward and laterally during Wisconsin glaciation into refugia in peninsula Florida and the Southwest (alluded to by Blair, 1958:460). Following the melt of the glacia- tion, S. J}ispichis appeared again in the southern Great Plains and seems still to be on the move northward (to the southern border of Nebraska in 1958 — Jones, 1964:212). As mentioned previously, S. hispidus is replacing Microtus ochrogaster as the dominant grass- eating, runway-making rodent in Oklahoma and parts of Kansas. Perhaps it was as late as Wisconsin times that conditions occurred to account for the evolution from S. hispidus of the distinctive S. fulviventer group. Today, these species generally replace (ecologic segregation) one another in and along the cordillera from Arizona and Texas southeastward to Oaxaca. Although there is some overlap (see profile, Fig. 4), one species dominates in each suitable montane environment: S. fulviventer in open, elevated grasslands; S. ochro- gnathus in bunch grasses on arid, rocky slopes; S. leucotis in mesic, boreal grass-shrub; and S. alleni in mesic, boreal-tropical grass- shrub. Presumably, basic stocks of S. hispidus occupied some of these habitats in the late Pleistocene with climatic, vegetational, and edaphic selective forces operating so as to produce the generally allopatric Recent species ( see Fig. 5 ) . Of the species of the S. fulviventer group, S. alhni might have been derived most recently from a stock of S. hispidus (from the westward in the Pacific coastal lowlands), whereas the other three species could have been derived from stocks of S. Jiispidus found on the Mexican Plateau. It is thought that S. fulviventer and S. alleni are less differentiated from S. hispidus than are S. ochrognathus and S. leucotis. The latter species seems most remote and could have branched off even earlier than the others, being set apart by unique features including rostral depressions and a reduced or absent lingual root on the first molar (see also Dalby and Lillevik, 1969). In summary, Sigmodon consists of one wide-spread, ubiquitous species, S. hispidus, and four derived species that occupy compara- tively small, allopatric ranges, mostly in western Mexico. Speciation in and along the cordillera in southwestern North America may have come about through ecologic segregation and morphologic di\'er- gence resulting from the availability of arid uplands, rocky slopes, and mesic boreal and mesic tropical-boreal habitats (presumably Baker — Sigmodon fulviventer Group 185 Sigmondon ochrognathus Xeric hillsides of desert mountains Sigmodon fulviventer Open grasslands in foothills and mountains Sigmodon leucotis Boreal grass-shrub Mexican Plateau stock Sigmodon hispidus Pacific Lowlands stock Sigmodon alleni Boreal-tropical grass-shrub Fig. 5. x\dapti\e relationships of Recent cotton rats. unoccupied by grass-eating rodents) in which the parent hispid species lacked survival ability. Selection for characters found in the species occurring in these habitats today was the result. Segregation and character displacement probably were intensified because of the general incompatibility of different kinds of cotton rats in the same living places. Key to Species of Cotton Rats ( Genus Sigmodon ) 1. Tail sparsely haired and scaly in appearance, individual scales broad, 0.75 mm. wide; skull generally long and narrow, basioccipital long and ]:)road, palatal pits shallow Sigrnodon his))idiis 1'. Tail heavily haired and not scaly in appearance, individual scales narrow, 0.50 mm. wide; skull generally short and broad, basioccipital either long and narrow or short and broad, palatal pits deeply marked Sigmodon fidviventer group, 2 2. Ears (inside of pinnae) whitish, in marked contrast to color of dor- sum; interparietal generally less than 2.0 mm. in length at midline; upper part of each premaxillary with pronounced rostral depression; 186 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. mesopterygoid fossa generally parallel-sided at anterior end; lingual root of first lower molar reduced in size and sometimes absent .._. S. leucotis 2'. Color of ears not conspicuously difl^erent from color of dorsum; interparietal usually 2.0 mm. or more in length at midline; upper part of premaxillary with slight or no rostral depression; mesopterygoid fossa generally not parallel-sided anteriorly; lingual root of first lower molar not reduced in size 3 3. Buff coloring on nose and around eye conspicuous; adult size small, length of head and body averaging 143 mm. and condylopremaxillary length averaging 32.0; auditory bullae small and elongate; median keel on basioccipital developed; lateral bulge of capsular projections of upper incisors pronounced; interparietal with slight to marked median posterior notch; paraoccipital process cur\'ed (when \aewed from ]:)elow) and notched on the anterior base S. ochrognathiis 3'. Buff color on nose and around eye usually not in marked contrast with rest of dorsum; adult size large, length of head and body averag- ing at least 168 mm. and condylopremaxillary length averaging at least 34.5; auditory bullae large and broad (relative to length of skull); lateral bulge of capsular projections of upper incisors slight to moderate; interparietal usually lacking any indication of a median posterior notch; paraoccipital process (when viewed from below) generally straight or slightly hooked 4 4. Color of dorsum always brownish, undeiparts washed with whitish or pale buff; adult size medium, length of head and body averaging 168 mm. and condylopremaxillary length axeraging 34,5; skull flattened in appearance, long and narrow; incisive foramina not extending to line drawn between anterior ends of first upper molars; basioccipital short and wide; mesopterygoid fossa broad anteriorly; median keel on palate slighdy de\eloped; palatal pits moderately deep; incisors usually markedly recurved ( opisthodont ) S. allcni 4'. Dorsum "pepper and salt" in color, undeiparts washed with buff; adult size large, length of head and body averaging 179 mm. and condylopremaxillary length averaging 36.5; skull arched, short and broad; incisive foramina extending to or beyond a line drawn be- tween anterior surfaces of the first upper molars; foramen ovale large, at least three-fourths diameter of third upper molar; basioccipital long and narrow; mesopterygoid fossa narrow anteriorK'; median keel on palate well developed; palatal pits markedly deep; incisors not highly recurved S. fulvivcnter Sigmodon alleni Sigmodon olleni, the brown cotton rat, is the most tropical- adapted member of the S. fulviventer group. Its preferred Hving places are in mixed grass-herbs-shrub areas in the Pacific coastal lowlands and extending up to the mesic boreal-tropical ecotone on the Pacific-facing slopes of the Sierra Madre Occidental, the Sierra Madre del Sur, and where these mountain chains join at the western end of the Trans-Mexican Volcanic Belt ( see Fig. 6. ) It is recorded Baker — Sigmodon fulviventer Group 187 from near sea level in Nayarit, Colima, and Oaxaca to as high as 3050 meters in Jalisco. Uahiiat and Habits The brown cotton rat seems to pref,er moist, vine- and shrnb- co\ered slopes in tropical or mixed tropical-boreal situations, and thereby occupies parts of the Tropical Deciduous Forest and humid Pine-Oak Forest (vegetation zones of Leopold, 1959). My acquain- FiG. 6. Geographic distrilKition of the Isrown cotton rat. 1. Sigmodoii allcni alleni. 2. Sigmodon alleni vulcaui. 3. Sigmodon alleni planifrons. tance with this species is from only four localities, although I spent time during each of several summers trying to find S. aUeni at places where it had been previously taken in Sinaloa, Nayarit, Jalisco, Michoacan, Guerrero, and Oaxaca. At one locality (in Michoacan) S. alleni was common, but at three others (in Sinaloa and Oaxaca) it was uncommon. As yet the habitat requirements of this species are poorly known, although it is surely more adapted to shrub habitat than to open grasslands. Specific trapping localities are discussed below. Sinaloa. — At 1.7 km. E Santa Lucia, 1720 ni., two 1:)rown cotton rats were trapped on June 23, 1955. This locality is on a Pacific-facing slope in the upper foothills of the Sierra Madre Occidental in tropical deciduous vegetation. 188 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. just below the pine-oak belt. Cotton rats were caught in a narrow canyon in dense second-growth shrub of a fallow corn field. The writer visited this place on several other occasions but caught no other S. alleni, although one S. hispidiis was lived-trapped there in the summer of 1967. Small mammal associates at this place included Liomijs pictus, Reitlnodontomys fulvescens, Peromyscus hoylii and Neotoma mexicana. Michoacdn. — Twenty-five S. alleni (12 males and 13 females) were taken 10 km. W Capacuaro, 2360 m., in grazed and logged pasture with scattered oaks and pines as the prominent woody vegetation. The cotton rats li\'ed in short, closely-grazed, grassy areas with scattered forbs coxering the dark volcanic soil. Some evidence of runways were found under shrubs and immedi- ately adjacent to rock walls (see Fig. 7). The animals were active both at night and dming daylight hours in this sparse habitat. Because it rained during most of our successful trapping period at this locality, I judge that cotton rat movements were not curtailed by precipitation. Several were seen moving across open, grazed turf bet\veen clumps of forbs or shrubs. Nests, presumed to be constructed by cotton rats, were found in rotting pine logs, imder volcanic rocks, beneath a pile of pine bark, and in a rotted pine stump, out of which Fig. 7. Habitat oi the brown cotton rat, Sii^iitodoii allciii, near Capacuaro, 2360 m., Michoacan. Photograph taken on July 22, 1967. a cotton rat was flushed. Grass used as nest material and also found as cuttings along runways was identified as Eiagrostis limhata. Owing to heavy grazing by cattle, this grass was able to mature only in protected clumps of shrubs or adjacent to rock fences. Other plants collected were species of the genera Hypiis and Ltipiniis, and Sohmiim eJacagnifoliinn. Of interest here is that 25 S. aUcni were ]i\e-trapped in two nights (July 20-21, 1967) in a sparsely- vegetated area of mixed pasture and fallow fields of less than 25 hectares. The Baker — Sigmodon fulviventer Group 1(S9 only other small mammal captured in the ]i\e-traps was Pcromyscus hotjlU. This ahility of S. allcni to li\e in an open area with \egetati\e co\er consisting of forhs and shrubs is in marked contrast to the little-disturbed grassy situations required as living places by S. fulviventer and S. ochrognathus. At Dos Aguas, 2135 m., Hooper ( 1961, 1962) found S. aUeni in growths of grass, poison ivy, other herbs, and shrubs in an' area of pine forest mixed with some broad-leafed oaks, alder, and madrone. Tree trunks and branches were draped with lichens, bromeliads, and orchids. Jalisco. — J. H. Batty collected 29 brown cotton rats on Volcan de Fuego ". . . at an altitude of about 10,000 feet, July 10 to 28, 1905" (Allen, 1906: 248). The exact hal)itat from which these rodents were taken is imknown. Previously in 1892, Nelson and Goldman (Goldman, 1951:180) had ascended adjacent Sierra Nevada de Colima without taking this cotton rat; a field party from the Michigan State University in 196.3 (Baker and Phillips, 1965) also climbed to the fir belt on this mountain without finding S. alh'ui, although S. hispidus was taken along grassy fence rows on the lower, southeastern slope. J. Knox Jones, Jr. (personal communication) reported that a field party from the University of Kansas Museimi of Natural History ascended the Volcan de Fuego in 1966 without finding brown cotton rats. Guerrero. — Nelson and Goldman (Goldman, 1951:152) obtained the brown cotton rat at Omilteme and subseciuently named it S. giierrerensis. In 1964, a field party from Michigan State University failed to reach this place owing to rains in the mountains but did collect, without finding brown cotton rats, in "similar" montane country near Xochipila, somewhat to the north of Omilteme. After spending several summers having little success in finding cotton rats at localities visited more than 60 years earlier by Nelson and Goldman, I have concluded that the scarcity or absence of this species is because many of the habitats in which it lived have been altered by man's land uses since the turn of the century. This change has presumably "eliminated" some of the pre- ferred living places of these cotton rats. Oaxaca. — The brown cotton rat was live-trapped on the Pacific side of the Sierra Madre del Sur at approximately 13 km. SSW Juchatengo, 1920 m. This locality, on the road between Oaxaca and Puerto Escondido, is approximately 200 meters below the seawardmost crest of the mountains and 18 kilometers east of Juquila, the type locality of S. planifron.s. The collecting site was in a transition between the pine-oak montane forests and the tropical semi-deciduous forests, the latter being mostly in protected, well-watered canyons (see Baker and Womochel, 1966). Cotton rats were live-trapped in second-growth vege- tation, often thick and tangled, in fallow, hillside cornfields. Plants growing on these abandoned fields belong to species in such genera as Rttbiis, Lupinus, Adianium, Castilleia, Solarium, Acalypha, Valeriana, Geranium, Cerastium, Cyperus, Hedyotis, Bomarea, Arbutus, and Tradescantia, and the species PJiytolacca decandra, Zeugites mexicana, Toxidendron radicans, and Ostrya virginiana. Small mammal associates obtained were Marmosa mexicana, Liomys irroratus, Onjzomys alfaroi, Reithrodontomys sumichrasti, Peromyscus megalops, Peromyscus evides, and Neotoma mexicana. On returning to the same locality three years later (in 1967), I was unable to catch any more cotton rats. Nowhere in Oaxaca have collectors obtained a large series of this rodent; George Goodwin (personal communication) reported six specimens taken at 190 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Santa Lucia as the largest number. I took four brown cotton rats near Juchatengo; near Capacuaro, Michoacan, we caught 25 specimens of S. aUeni along with one small mammal associate, Peromijscus botjlii. Two young S. alleni were captured ali\'e in a grassy roadside ditch next to a poorly-drained palm jungle 8 km. ESE Rio Grande, ele\ation less than 30 in., in July, 1967. This low, moist area adjoined a coastal mangrove swamp. Taken at the same place were Liomtjs pictiis, Tijlomijs niidicaudus, Peromijscus mexi- canus, and Neotoma mexicana. Association of brown cotton rats witli other species of ilie genus. — There is no report of S. alleni li\'ing in ecological association with S. fulviventer, S. leticotis, or S. ochrognathiis. On the western slopes of the Sierra Madre Occi- dental in Durango (see Fig. 4) and southeastward, the ranges of S. alleni and S. leticotis might meet at the junction of the pine-oak belt and the tropical habitat. It is also possible that S. alleni and S. fulviventer may occupy some- what the same areas in the vicinity of Patzcuaro in Michoacan, where Nelson and Goldman caught a large series of the latter in the 1890's and Hall and Villa-R. (1949:465) took the former species, which they erroneously identified as S. melanotis. The latter authors also took S. hispidus at the same place. It is suspected that in the Patzcuaro area S. alleni occupies brushy areas, and S. fulviventer and S. hispidus occupy grassy situations. I failed to obtain any of the species directly west of Patzcuaro in the summer of 1963. Near Santa Lucia in Sinaloa, S. hispidus was captured in a run\\'ay under a dense tangle of Acacia and Mimosa on a moist, tropical hillside. This place is not unlike that where S. alleni was taken nearby a few years previously. Near Carapan in Michoacan, S. hispidus was trapped in open sacaton meadows, whereas S. alleni was caught in overgrazed shrubs not many kilometers away near Capacuaro. Since S. hispidus has proved to be an aggressive species elsewhere, such as extending its range northward from the Oklahoma-Kansas line to Nebraska in a space of about 56 years (Cockrum, 1948, and Jones, 1964:212), there is good reason to believe that S. hispidus may usurp habitat (possibly altered by man) formerly inhabited by other species of cotton rats. Specific Characters and Comparisons A rich, brownish dorsum together with medium size ( for captive animals, maximum weights are 178 grams for a male and 180 for a non-pregnant female; ma.ximum lengths of head and body are 173 mm. and 183, respectively) and strongly recurved incisors (opistho- dont) distinguish S. alleni from other species in the S. fulviventer group. Other unique characters include skull with flattened appear- ance when viewed laterally, bulge of capsular projections for the upper incisors slight, and paraoccipital processes, when viewed from below, slightly hooked rather than straight or curved. From S. fulviventer, S. alleni differs further in having underparts washed with \\'hitish or pale buff rather than tawny; skull long and narrow instead of short and broad; auditory bullae smaller in rela- tion to breadth; basioccipital short and wide instead of long and narrow; posterior ends of incisive foramina usually not extending Baker — Sigmodon fulviventer Group 191 (rather than extending) to a hnc drawn between the anterior sur- faces of the first upper molars; anterior end of mesopterygoid fossa broad instead of narrow; anterior Hp of foramen magnum obviously (rather than slightly) notched; foramen ovale small (no more than half width of M3) instead of large (at least three-fourths width of M3); palatal pits shallow rather than deep; and median keel of palate slightly developed instead of well de\ eloped. From S. leticotis, S. alleni is further distinguished by hairs of inside of ear not whitish in contrast to rest of dorsum; skull long and narrow instead of short and broad; auditory bullae smaller in relation to breadth; basioccipital short and wide instead of long and narrow; posterior ends of incisive foramina usually not extending (rather than extending) to a line drawn between the anterior sur- faces of the first upper molars; anterior end of mesopterygoid fossa broad rather than parallel-sided; length at midline of interparietal more (instead of less) than 2 mm.; anterior lip of foramen magnum obviously (rather than slightly) notched; rostral depressions on sides of premaxillae slight instead of deep and pronounced; angular process of lower jaw rounded instead of slightly hooked; lingual root of first lower molar large rather than reduced or absent. From S. ochrognathus, S. aUeni differs further in nose lacking extensive and contrasting yellow coloring; skull long and narrow instead of short and broad; auditory bullae larger and broader; median keel on basioccipital slight instead of obvious; bulges of capsular projections for upper incisors slight rather than pronounced; median-posterior area of interparietal lacking distinct notch; and paraoccipital process (from ventral view) slightly hooked rather than curved with a basal notch. From S. liispidus, S. alleni is distinguished by small size of tail scales (0.5 mm. wide rather than 0.75 mm. wide); tail heavily haired instead of sparsely haired; incisors usually more strongly recurved ( opisthodont ) ; basioccipital short in relation to breadth rather than long; paraoccipital processes (from ventral view) slightly hooked instead of generally straight; and palatal pits moderately deep rather than shallow. Geographic Variation Brown cotton rats occur along the Pacific-facing mountains and foothills from southern Sinaloa southeastward to eastern Oaxaca at the Isthmus of Tehuantepec. Probably their systematic relationships have remained unclear because of the a\'ailability of only a few scattered specimens in museum collections. These have been given an assortment of no less than six specific names since 1902, when 192 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Vernon Bailey named S. alleni (see Hall and Kelson, 1959:676-679). Like S. leucotis, S. aUeni seems to occupy a disjunct range with field collectors being especially lucky to pick up more than one or two individuals at any locality. Field parties from the Michigan State University worked the Pacific slopes from Sinaloa to Oaxaca at- tempting to gather specimens from heretofore unreported and inter- mediate localities. Little additional material was obtained, although live animals from near Capacuaro, Michoacan, and from near Jucha- tengo, Oaxaca, were successfully bred as well as crossed in the live colony (the findings from this study will appear in a later report). Herein, cotton rats previously assigned to the specific names S. gtierrerensis, S. macdoiigaUi, S. macrodon, S. plonifrons, and S. vulcani all are arranged as a single species under S. alleni, the oldest available name. All share the common specific characteristics as presented in the prexious section and may differ from one another in minor ways that demonstrate intraspecific geographic variation. In general, these cotton rats are larger and darker in the montane areas and smaller and paler in coastal situations. However, popula- tions in the northwestern part (assigned to S. a. alleni) and in the southeastern part (assigned to S. a. planifrons) of the range of the species are both smaller and paler than populations from the central sector (assigned to S. a. vulcani) of the species distribution. To determine the degree of size difference, measurements of the con- dylopremaxillary lengths of the wild-taken animals listed in Table 1 were evaluated by analysis of variance. The overall differences be- tween the means of this cranial dimension are just significant at the five per cent level (F^3.72). The degree of difference between the indix'idual means of the four samples was then determined by the new multiple range test (see Table 2). Population means under- scored by a common line in the table are not significantly different. As suggested above, the smaller animals representing S. a. alleni from the northwestern part of the range (Sinaloa, Nayarit, and northern JaHsco) and representing S. a. planifrons from the south- eastern part of the range (Oaxaca) are not significantly different from each other, but are significantly different from the two samples from the central part of the range (southern Jalisco and Michoacan) that represent S. a. vulcani. Sigmodon alleni alleni Bailey Sipmodon alleni Bailey, Pioc. Biol. Soc. Washington, 15:112, June 2, 1902. Type. — Young adult male, skin and skull; no. 88227 U.S. National Museum; from San Sebastian, Mascota, Jalisco; obtained on March 15, 1897, by E. W. Nelson and E. A. Goldman, original no. 10708. Baker — Sigmodon fulviventer Group 193 g 173 < a z o H H O U Z o 03 H Q < O z o O « H X H a z W o EC w z H < Q U H O w aa C cS 5 I'd < tc2 •S8 c'V N IP S s «i o ll-S ■Sft c S K c II: Mug 1-4 O C re O D-S "re 5 * 5 o Sb C/3 Tj< i> ^ o lO ^ (M i3 1 05 coco ceo irj CD cc ^2 °^co 00 CO ^lO ino ^' lO co2 s 2-t a '^. CO ~ CO CO '^ in coed T^cd COOT cdtN CO CO t~ ^J^ -f oo2 2q 2-1 2^1 Ol Ol GO ^H ^2 2 CO 23 CO ci cq Xl Gi ^2 -^2 So 2t- o c? t-H '^ t- CD coin coin -t in incq in^ inVi in in in in q2 2^^ 00 co' = q2 2o oi CO CD ^in coin ino> in'csi — t* in CO t- S oc -^2 2^ t^ ~ X ^ in CO co^. CO CO ?- ^CO CO H Cj CD CO CO in o o ^- o o ^— ^ CO o co CO CC o CO (N c^ ^ s CO oq 1 -^CM o cJ5 of^i 6 1 <^6 fM c^id) C m CD S-^ S-=^ in 1 CO , ^o — -3 c c ^ s C ^" .^ 0) c .^ s '3 0; *^ o p 1 . « S c *c5 0^ ~ ^, a = i! ~ < 2 m 194 Misc. Publ. 51, Unr'. Kansas Mus. Nat. Hist. Range. — Mixed grass-forb-shrub areas on western slopes of the Sierra Madre Occidental and adjacent Pacific coastal lowlands from southern Sinaloa south- ward to northwestern Jalisco (see Fig. 6). Diagnosis. — Size small for the species ( see Table 1 ) ; dorsum intermixed with black hairs and agouti-banded hairs of Ochraceous-Tawny; underparts and upper surfaces of feet whitish or pale buff; base of tail slightly darker than dorsum; skull short and broad with short rostnmi and small auditory bullae. Comparisons. — From S. a. vulcani, S. a. alleni differs in size smaller (see Talile 1 ) ; color paler ( upperparts Ochraceous-Tawny rather than Clay Color ) ; skull smaller with flatter cranium, shorter rostrum, and less expanded auditory bullae. Remarks. — This northernmost subspecies of S. alleni is characteristically pale in color and smaller than adjoining S. a. vulcani. Specimens have been taken at elevations from near sea level at San Bias up to 1723 meters near Santa Lucia. In its coastal habitat, S. a. alleni probably comes into some contact with S. hispidiis. At Santa Lucia, alleni was caught in hillside fallow-field habitat in 1955 and hispidus was taken in 1967 in approximately the same place. S))ecimens examined (20). — Sixaloa: 2 km. E Santa Lucia, 1723 m., 2 (KU); Copala, 4 (LACM). Nayarit: San Bias, 1 (US); Tepic, 2 (US); Valle de Banderas, 1 (US). Jalisco: San Sebastian, 10 (US). Sigmodon alleni vulcani J. A. Allen Sigmodon vulcani J. A. Allen, Bull. Amer. Mus. Nat. Hist., 22:247, July 25, 1906. Sigmodon guerrerensis Nelson and Goldman, Proc. Biol. Soc. Washington, 46: 196, October 26, 1933, type from Omilteme, 2440 m., Guerrero. Type. — Young adult female, skin and skull; no. 26310 American Museimi of Natinal History; from Volcan de Fuego, 3050 m., Jalisco; obtained on July 25, 1905, by J. H. Batty, original no. 2330. Range. — Western slopes of Sierra Madre Occidental and Sierra Madre del Sur and coastal plain from southwestern Jalisco southeastward to southern Guerrero (see Fig. 6). Diagnosis. — Size large for the species ( see Table 1 ) ; dorsum intermixed with black hairs and agouti-banded hairs of Clay Color; underparts and upper surfaces of feet whitish or pale buff; base of tail slightly darker than dorsum; skull large and broad with cranium abruptly expanding posteriorly; auditory bullae large. Table 2. — Result of new multiple range test on condylopremaxillary LENGTHS OF CRANIA OF SAMPLES OF Sigmodon olleili. POPULATION MEANS UNDERSCORED BY A COMMON LINE ARE NOT SIGNIFICANTLY DIFFERENT. s. a. planifrons S. a. alleni S. a. vulcani Locality Tehuan- tepec, Oaxaca Sinaloa, Naya- rit, northern Jalisco Volcan de Fuego, Jalisco Michoacan Means of condylo- jremaxillary engths 30.80 31.10 32.18 32.53 Baker — Sigmodon fulviventer Group 195 Comparisons. — For comparison with S. a. alleni, see account of that sub- species. From S. a. planifrons, S. a. vtilcani dilFers in size larger; color of upperparts darker (near Clay Color rather than Cinnamon-Buff); skull larger and broader; skull flatter; nasals longer; incisors less recur\ed. Remarks. — This large, dark subspecies occurs from near sea level in Colima to a])o\e 3000 meters in Guerrero. It occupies a variety of hal^itats from mesic, l)orcal-tropical, montane forest-shrub to coastal shrub-vine areas. In many places its distribution seems to be interdigitated with populations of S. hispidus. Speciryiens examined (67). — Jalisco: 10 km. SSW Autlan, 1372 m., 2 (UM); 9 km. NNW Barro de Navidad, 2 (KU); Volcan de Fuego, 3050 m., 36 (AMNH). Colima: 3 km. E Santiago, 1 (KU). Michoacax: 3 km. W Patzcuaro, 2380 m., 2 (MVZ); 6 km. S Pdtzcuaro, 2350 m., 2 (MVZ); 14 km. E on road from Angahuan, 2300 m., 2 (UM); i.5 km. E on road from Anfiahuan, 2300 m.. 2 (UM); 10 km. W Capacuaro, 2059 m., 3 (MSU); 9 km. N Uruapan, 1 (UM); 7 km. N and 2 km. W Uruapan, 1937 m., 1 (KU); Urtiapan, Cupatitzio National Park, 1 (UM); 23 km. W Dos Aguas, 2135 m., 5 (UM); Dos Aguas, 2135 m., 3 (UM). Guerrero: Omilteme, 2440 m., 1 (UM),2 (US). Other record. — Michoacax: Tancitaro, 1830 m. (Hall and Villa-R., 1949: 465). Sigmodon alleni planifrons Nelson and Goldman Sigmodon planifrons Nelson and Goldman, Proc. Biol. Soc. Washington, 46:197, October 26, 1933. Sigmodon planifrons minor Goodwin, Amer. Mus. Novit., 1705:1, Fel)ruary 4, 1955, type from Santa Lucia, 1220 m., 12 km. NE Tenango, Tehuantepec, Oaxaca. Not Sigmodon minor Gidley, 1922. Sigmodon macdougalli Goodwin, Amer. Mus. Novit., 1705:3, February 4, 1955, type from Santo Tomas Teipan (rain forest abo\e village), 2135 m., 12 km. S San Bartolo Yautepec, Yautepec, Oaxaca. Sigmodon macrodon Goodwin, Amer. Mus. No\it.. 1705:4, February 4, 1955, type from Cerro San Pedro (rocky summit), 1098 m., 20 km. W Mixtequil- la, Tehuantepec, Oaxaca. Sigmodon planifrons setzeri Goodwin, Jour. Mamm., 40:447, August 20, 1959, a renaming of S. p. minor Goodwin. Type. — Young adult female, skin and skull; no. 71918 U.S. National Mu- seum; from Juquila, 1525 m., Oaxaca; olitained on February 28, 1895, by E. W. Nelson and E. A. Goldman, original no. 7569. Range. — Western slopes of the Sierra Madre del Sur and adjacent Pacific coastal lowlands of southern Oaxaca eastward to the Isthmus of Tehuanatepec (see Fig. 6). Diagnosis. — Size small for the species ( see Table 1 ) ; dorsum intermixed with Ijlack hairs and agouti-banded hairs of near (a) Cinnamon-Buft'; imder- parts and upper surfaces of feet whitish or pale buff; base of tail slightly darker than dorsum; skull small and flat; rostrum depressed; incisors markedly recurved. Comparisons. — For comparison with S. a. vidcani, see account of that sub- species. Remarks. — This subspecies is smaller (especially those from Tehuantepec) and .shghtly less richly colored than S. a. vulcani, its relative directly to the 196 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. northwest. Although much of the available study material consists of young animals, the few adults present show that there is considerable variation between populations in coastal Oaxaca. Animals from lower elevations are smaller and those from mesic tropical situations on the higher slopes seem larger. Goodwin ( 1955 ) detected some of this \'ariation and quite reasonably named three taxa from the area of Tehuanatepec. However, a comparison of his material with the recently-obtained and laboratory-raised animals from near Juchatengo shows that the differences are not of sufficient magnitude to warrant retention of these taxa and that all of the populations should be arranged imder the oldest name, S. a. planifroiifi. The arid tropical shrub habitat in coastal areas of Oaxaca is chiefly the home of S. hispidus, with grayish S. h. mascotensis to the westward and brownish S. h. ischyrus to the eastward. The distributional relationship between S. alleni and S. hispidus in this area is obscure, although S. allcni in the low- lands can be expected in highly mesic situations, such as palm forests near mangrove. The brownish S. h. ischyrus resembles S. alleni in color and in tail hair, but is larger with a longer tail and shorter, thinner pelage. Specimens examined (29). — Oaxaca: Santo Tomas Teipan, 21.35 m., 12 km. S San Bartolo Yautepec, Yautepec, 1 (AMNH); Arroyo Palmar (Tequi- sistldn), Tehuantepec, 3 (AMNH); Arroyo Arenal, Tehuantepec, 3 (AMNH); Cerro PoUe, Tehuantepec, 3 (AMNH); Cerro del Chorro, Tehuantepec, 1 (AMNH); Cerro de Pastle, Tenango, Tehuantepec, 1 (AMNH); Cerro Ocate, Tenango, Tehuantepec, 1 (AMNH); Llano de Ocate, Tehuantepec, 2 (AMNH); Tres Cruces, Tehuantepec, 5 (AMNH); Santa Lucia, 1220 m., 1 (AMNH); Cerro San Pedro, 1921 m., 20 km. W Mixtequilla, 1 (AMNH); 40 km. SSE Miahuatlan, 1647 m., 1 (CAS); 2 km. NNW Soledad, 14.33 m., 2 (KU); 13 km. SSW Juchatengo, 1921 m., 1 (MSU); Juquila, 1525 m., 2 (US); 8 km. ESE Rio Grande, 30 m., 1 (MSU). Sigmodon fulviventer Habitat and Habits The tawny-bellied cotton rat (Fig. 8) is an inhabitant of the mesquite-grassland that occurs in a north-northwest to south-south- east direction along the eastern base of the Sierra Madre Occidental (see Leopold, 1959:27-28). This range extends northward to central New Mexico and Arizona and southward to the northern base of the Transverse Volcanic Belt in Jalisco and northern Michoacan (see Fig. 15). To the westward, the mesquite-grassland merges with the pine-oak of the higher elevations of the mountains at approximately 2000-3000 meters. To the eastward the growing aridity of the lower elevations causes a gradual change to the desert. Leopold (loc. cit.) noted that the mesquite-grassland has been the major Mexican habitat for the pronghorn (Antilocapra americana), the mule or burro deer (Oclocoileus hemionus), the white-sided jackrabbit (Lepus callo- Baker — Sigmodon fulviventer Group 197 •*4«*i^ Fig. 8. A tawny-bellied cotton rat, Sigmodon fulviventer, captured near Bo- quilla, Durango, on July 10, 1965. Photograph taken in October, 1965, by Robert Brown. tis), and for such rodents as the banner-tailed kangaroo rat (Dipo- domys spectabilis), the grasshopper mouse (Onijchomys torridusj, the northern pygmy mouse (Baiomys taylori), the spiny pocket mouse (Liomys irroratus), the hispid pocket mouse (Perognathus hispidus), and the tawny-belHed cotton rat (S. fulviventer). How- ever, as Leopold stated, much of this fine grassland, interspersed with mesquite, acacias, cacti, agaves, and herbaceous plants, has been depleted by overgrazing. Today, habitats suitable for cotton rats consist of scattered plots, which have been protected from heavy grazing by cattle, goats and sheep, along fence lines, at edges of cultivated fields, along rights-of-way of highways and railroads, and in situations where low thorny shrubs protect grasses under- neath. The reduction in the quality of the habitat for cotton rats and other grassland mammals is not a recent development; E. A. Goldman (1951:291), who went to Zacatecas in December, 1902, hoping to collect topotypes of S. fulviventer, wrote: "The season had been a dry one and at the time of my visit the hills, overgrazed 198 Misc. Publ. 51, Uxiv. Kansas Mus. Nat. Hist. Fig. 9. Runway of the tawny-bellied cotton rat, Sigmodon fulvicenter, in grass belonging to species of the genera Bouteloua and Muhlenhcrgia. Photo- graph taken near Atotonilco, 2040 m., Durango, on July 11, 1967. by goats, were nearly bare, leaving no local habitat suitable for the cotton rat." Tawny-bellied cotton rats have been found in association with bunch grasses. Their well-worn runways may be completely hidden in thick, grassy cover or may be periodically exposed (see Fig. 9) with segments of trails covering distances over bare ground of as much as a third of a meter between grassy clumps. Plant and animal associates are described in the following paragraphs. CliihuaJuia. — Ta\\ny-bellied cotton rats were found in open, moderately- grazed grasslands. One such place (2 km. N Gallego, 1610 m. ) had hea\'y grass ( Miihlenbergia sp. ) in poorly-drained areas \\ ith niunerous nmways paralleling roadside or railside ditches (see Fig. 10). Other plants collected were KiiJjnia chlorolepis, Engclmannia pinnatifida, Aphanostcplius ramosissimiis, Allionia sp., Baileya mtiltiradiata, Jatropha niacruJUza, Hedijotis rubra, and Evolvidtis sericeus. Small mammals obtained in association with S. fulvivei^ter at the Gallego locality were Dipodomijs spectabdis, Pcrognaditts liispidiis, Pcrognathtis flaviis. Pcrognaditis nclsnni, Baiomys tot/Iori. Onychomys torridus, Rcithrodontoimjs megaloti.s, RcitIuodo)iloi)iyf> niontaniis, Peroinyscus inanicu- latus, and Neotoma albigula. Although this locality was \isited on two occasions (in 1965 and 1967), only one S. liispidiis was captured. This indicates that at least two cotton rats were present, I)ut S. liispidus \\ as scarce and S. fidviven- ter was common, based on trap success. Baker — Sigmodon fulviventer Group 199 il Fig. 10. Ele\ated grasslands near Gallego, 1610 m., Chihuahua. The dry bunch grass is inhabited by die tawny-bellied cotton rat, Sigmodon fulviventer. Photograph taken on July 4, 1965. Durango. — At 3.3 km. NE Boquilla, 1952 m., tawny-bellied cotton rats were caught in the level part of a mountain valley floor in mixed grassland, mesquite, acacia, juniper, and oaks (see Fig. 11). Grasses were mostly Miihlenbergia sp. and Aristida sp. Composites present were Erigcron sp., LeucoJene cricoidcs, and Sanvitalia sp. Nightshade (Solanum sp.) also was present in the vicinity of runways. Small mammal associates included Perognathus nelsoni and, on adjacent hillsides, S. ochrognathus. At 12 km. NNE Boquilla, 1890 m., a locality just abo\e the Durangan grassland plains to the eastward but \\ithin a scattered stand of juniper, acacia, Mahonia thfoliaia, and mesquite, S. ftd- viventer was captured in runways in clumps of grass ( Mtdilenbergia sp. ) and scattered composites, Baileya sp. and Haplopapptis spinulosus. Small mammal associates included Notiosoiex craicfordi (see Baker, 1966:345), Perognathus jiavus, Perognathus nelsoni, Perognathus hispidus, Reithrodontonnjs megalotis, Onycliomys torridus, Baiomys taylori, and (on adjacent hillsides) S. ochrogna- thus. At 9 km. NNW Canatlan, 1952 m., S. fidviventer was caught in runways in a dense stand of grasses, Bouteloua gracilis and Muhlenbergia sp., which were protected from intense grazing by an overhead growth of low acacia. Also present were Verbena sp., Perymenium sp., and Haplopappus spinulosus. Runways led from one clump of grass to another, tlirough bunches of prickl>' pear (Opuntia sp.), among rocks, and between roots of huisache and acacia. One S. fidviventer was dug out of a burrow, which was appro.ximately three- fourths of a meter long with a tunnel diameter of 45 mm. Other mammals caught in these runways were Liomys irroratus, Perognathus nelsoni, Reithro- 200 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 11. Field camp in oak grove near Boquilla, 1952 m., Durango. The sparsely-vegetated hillsides are occupied by the yellow-nosed cotton rat, Sig- yuodou ochrognathus, and the \alley floor by the tawny-bellied cotton rat, Sigmodon fidviventer. Photograph taken on July 1, 1965. dontomtj.s megalotis, Peromyscus pectoralis, Baiomys taylori, and, on adjacent hillside.s, S. ochrognaihus. In the vicinity of Hacienda Coyotes, 2475 ni., tawny-bellied cotton rats were trapped in open grassy meadows surrounded by pine-oak vegetation characteristic of the higher parts of the Sierra Madre Occidental. These rodents and their runways were most common in bunch grasses adjacent to rock fences, and seemed to a%oid stands of tall sacaton grass, in which Microtus mcxicanus was the only grass-eating rodent captured. The meadow was dotted with plants belonging to species of the genera Verbena, Cnapha- lium. Achactogcron. Commcliua, Hctcrodieca, and Ranuucultis, and to Achillae lamdosa and Taraxacum ufficinale. Other small mammals caught in cotton rat runways were Reithrodontomijs megalotis, Peromyscus melanotis, and Pero- myscus boylii. Sigmodon leucotis and Microtus mexicanus were present, but not trapped in the same areas, and were presumably ecologically segregated. At 5 km. SE Tepehuanes, 1789 m., one S. fidviventer was trapped in a small patch of Johnson grass, Sorghum halepense, in an apple orchard that was protected from grazing by a rock fence. This patch also produced a catch of Baker — Sigmodon fulviventer Group 201 Fig. 12. Mixed desert shrub and mesquite grassland near Atotonilco, 2040 m., Durango. Here, the tawny-ljellied cotton rat, Sif^moclon fulviventer, is the dominant grass-eating rodent and the hispid cotton rat, Sigmodon Jiispidiis, is less common. Photograph taken on August 11, 1967. Liomys inoratus, Ferognathus flavus, Rcithrodoutomijs megahtis, Peiomij.scus hoylii, and Pewwysciis truei. The latter two species were taken adjacent to a high canyon wall that bordered the orchard on one side. At Hacienda Atotonilco, 2040 m., tawny-bellied cotton rats were found in distinct, well-used runways (see Figs. 9 and 12) in mixed grass, weeds, and shrubs along an arroyo. Clumps of grass were identified as blue gramma, Botitelotia gracilis, and Muhlenbergia sp. Runways also led through tall weeds of the genus Viguiera. Verbena hipinnatifida also was collected in the cotton rat area. Thorn shrubs of the genus Mimosa made up the woody cover along the arroyo; pods emptied of the beans w^ere found in small piles along runways. It was supposed that S. fulviventer or other rodents used this food. Other small mammals captured in runways and adjacent habitats included Notiosorex crawfordi, Liomys irroratus, Perognatlius flavus, Perognatlius hispidus, Reith- rodontomys fulvescens, Baiomys taylori, and Sigmodon hispidus. S. hispidus was uncommon, and S. fulviventer seemed to dominate as the grass-eating njdent in the community. Zacetccas. — One S. fidviventer was hand-caught in mid-afternoon in a rim- way in tall grass, Muhlenbergia sp., at 13 km. S Villanue\'a, 2090 m. Guanajuato. — Runways of S. fulviventer were noted in elevated grassland sinroimded by oak-covered valleys in the mountains of extreme northwestern Guanajuato at 8 km. SW Ibarra, 2500 m. (see Fig. 13). Tliis cotton rat was taken in runways in open country and near the edge of the oak timber in mixed grass and low-growing scrub oak, Quercus sp. Most runways were through grasses belonging to species of the genera Muhlenbergia, Stipa and Bouteloua. 202 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. Fig. 13. Open grassland and oak-filled canyons near Ibarra, 2500 m., Guana- juato. The mixed grass, forbs, and scrub oak clumps in the foreground are occupied by the tawny-bellied cotton rat, Sigmodon fidviventer; the rocky canyon slide in the background is the habitat of the white-eared cotton rat, Sigmodon leucotis. Photograph taken on July 19, 1966. Moderate grazing by cattle seemed not to be a limiting factor on cotton rat distribution over this broad grassland. Other plants identified were Euphorbia sp., Oenothera sp., Milla hiflora. Dahlia coccinea, OxaUs sp., Sisyrinchium sp., Verhesina sp., Calochartus sp., Zemenia sp., Hijpoxis .sp., Castilleia sp., Achae- togeron sp., Baccharis ghitinosa, Linum sp., Bouvardia sp., and Giitierrezia ghttinosa. Other small mammals taken in runways were Peromyscus manicidatus and, on adjacent hillsides, S. leucoiis. The skull of a cotton rat, disgorged by a gopher snake, Pituophis sp., was obtained at this locality. A nest containing four young S. fulviventcr (with eyes not yet open) was found on July 21 imder a large rock (30 by 60 centimeters), adjacent to a rock wall in an abandoned corral (see Fig. 14). The nest was of shredded grass about 75 mm. in circum- ference and 50 mm. high, and situated in a shallow depression about 25 mm. deep and 100 mm. across. Jalisco. — Taw n\'-bellied cotton rats were captured (mostly by hand) in mi.xed \egetation in a fence row bordering a field of carrots at 2 km. NW La Barca, 1525 m. Grass and weeds were growing in piles of mesquite branches, which had been placed over the vegetation on the field side of the barbed-wire fence. The runways, mostly directly under the fence wire, led through thick Bermuda grass (Cynodon dactylon), with some morning glory {Ipomoca sp.) growing on the fence. Cuttings of both morning glory and Bermuda grass were found in rodent trails; a nest constructed entirely of Bermuda grass \\'as found along one runway. The field part\- visited this place between 2:00 and 4:00 p.m. on Jul>' 14, 1966, set Sherman li\e-traps in runways at one end of the fence line and, starting at the other end, dro\ e any animals using the run- Baker — Sigmodon fulviventer Group 203 ways toward the traps. This action was repeated se\eral times. Either captured or obser\ed were the anipliihians, Rana pi))icns and Hyhi cxiivia, the reptiles, Sceloponts toiqiiatiis, Cnemidophortis scalaris, and Thamnophis sp, and Baiomys taylori. Sigmodon hispidus was captured nearby, within the \egetable field but not in the fence row. At 2/2 km. W Mazamitla, Hooper (1955:21) captured one tawny-bellied cotton rat in a plant community consisting of grass, weeds, cactus, scrub oak, and a few shrubs. This place was in the oak belt, altitudinally just below the pine forest. Less than two kilometers away he captured S. Jiisjtidus in under- storx' plants including grass, blackberry, and Salvia. Fig. 14. Nest of young of the tawny-bellied cotton rat, Sifj.inodoii fidviventer, found under a rock near Ibarra, 2500 m., Guanajuato. Photograph taken on July 19, 1966. New Mexico. — Mohlhenrich ( 1961 ) found taw ny-bellied cotton rats at ele- vations of 1200 to 1920 meters, mostly associated with piiion, oak, and juniper, and often found in swales containing thick grasses such as Hilaria jamesii. Association of iaicity-hellicd cotton rats witli other species of tlie gemis. — Sigmodon fulviventer has been taken in association with or immediately adjacent to S. hispidus, S. leucotis, and S. ochrognathus (see Fig. 4). Probably S. /(//- 204 Misc. Publ. 51, Unr'. Kansas Mus. Nat. Hist. viventer and S. alleni do not co-exist liecause of their differing ecological preferences. In the grasslands on deep alluvial soils along the eastern base of the Sierra Madre Occidental, S. fulviventer dominates or presumably excludes other cotton rats. When found in the xicinity of either S. leticotis or S. oclirognathiis, S. fulviventer occupies the level, open areas lea\ing the periphe al rocky, sparsely-vegetated slopes to the former. However, where .S. fulviventer is absent, S. leucotis (in Durango west of San Luis and southwest of ^'icente Guerrero) and S. ochrognathus (in Coahuila in the Sierra del Carmen and southwest of Ocampo and in Texas in the Chisos and the Davis mountains) may take over all available grassy habitats. Whereas S. fulviventer comes in contact with S. leucotis and S. ochrognathus in the higher foothills and in mountain meadows of the Sierra Madre Occidental, S. fulviventer is more apt to li\e in some degree of association with S. hi.spidus in the lower, eastern parts of its range, especially where the mesquite grasslands and the desert habitat interdigitate. In New Mexico, Mohlhenrich ( 1961 ) found hispid cotton ^ats more common in plant commimities containing Cottonwood trees, joint-fir, cat- tail, saltbush, mesquite, creosote-bush, choDa, and prickly pear and tawny- bellied cotton rats more common in communities containing pinon, juniper, evergreen oak, and grasses such as Hilaria jamesii. In areas where both species occur in New Mexico, S. fulviventer is found at higher elevations with lower temperatures and more vegetatixe cox'er, whereas S. hispidus occurs at lower elevations with higher temperatures and more sparse vegetative cover. Tliis same situation seems to prexail where the distribution of these species adjoin along the western border of the Mexican Plateau. In the northern part (in Chihuahua near Gallego and in Durango at Atotonilco) S. fulviventer appeared, at least from our trapping records, to be more abundant than S. hispidus. In more humid Jalisco (near La Barca), however, we captured almost equal nimibers of each (fixe S. fulviventer and four S. hispidus), although each species was from a different part of a cultivated field. It would seem that the ftdviventer group of cotton rats saturates most suitable habitats in the western part of the Mexican Plateau, in the adjacent Sierra Madre Occidental, and in montane grasslands from Trans-Pecos Texas and Coahuila westward to Arizona, Chihuahua, and northern Durango. In southern Zacatecas, Jalisco, and Michoacan, where rainfall increases markedly, S. hispidus takes over more of the available grassland habitat, apparently restricting greatly the areas used by S. fulviventer and S. leucotis. In these states, grassy places that in Durango might ordinarily harbor S. fulviventer contain only S. hispidus. Elevated grasslands in eastern Chihuahua, western Texas, and western Coahuila seem entirely suitable for occupancy by S. fulviventer, although now are included in the ranges of S. ochrognathus (in the higher areas) and S. hispidus (in the lower areas). It would appear diat S. fulviventer has been unable to "cross" desert country in the \icinity of the Rio Grande in New Mexico and Texas and in the Bolson de Mapimi in Chihuahua and Coahuila to reach these areas to the eastward. The success of S. ochrognathus and the ubiquitous S. hispidus in occupying these desert mountains suggests that they, as species, can survive more xeric conditions than S. fulviventer. Parasites. — Dr. Robert Traub identified from S. fulviventer the fleas, Poly- genis martinez-haezi Vargas, 1951, and Archopcas Icucopus ssp. from near Baker — Sigmodon fulviventer Group 205 Boquilla, and Picochaetis sp. from near Hda. Coyotes. Doran (1955:164) recorded die nematode, Litomosoidcs carinii (Travassos, 1919), from S. /. melanotis. Specific Characters and Comparisons The "pepper and salt" colored upper parts and the tawny under- parts, coupled with large size (for captive animals, maximum weights are 222 grams for a male and 206 for a non-pregnant female; maximum lengths of head and body are 197 mm. and 200, respec- tixely) distinguishes S. fulviventer from other members of the S. fulviventer group. Other unique characters include: anterior end of mesopterygoid fossa narrow; foramen ovale large ( at least three- fourths width of M3); palatal pits markedly deep; and median keel on palate well developed. From S. alleni, S. fulviventer is further distinguished by skull more arched, short and broad rather than long and narrow; incisors less recurved; basioccipital more elongate in comparison to width; auditory bullae, in relation to size of skull, larger; posterior ends of incisive foramina extending (instead of not) to or beyond a line drawn between the anterior surfaces of the first upper molars; and paraoccipital process, when viewed from below, straight instead of hooked. From S. leucotis, S. fulviventer differs further in interparietal more than (instead of less than) 2 mm. long; rostral depressions on upper premaxillary slight instead of pronounced; angular process of lower jaw more rounded and less hooked; and lingual root of first lower molar normal, not reduced or absent. From S. ochrognathus, S. fulviventer is further distinguished by whitish tips of hairs on inner side of pinnae that do not contrast with color of pelage of rest of head; auditory bullae large and broad rather than small and elongate; median keel on basioccipital slight instead of obvious; anterior lip of foramen magnum not obviously notched; bulge of capsular projections of upper incisors moderate rathc-r than pronounced; median-posterior notch in interparietal absent instead of present; and paraoccipital process (in \entral view) straight instead of curved with basal notch. From S. hispidus, S. fulviventer differs in small size of tail scales (0.5 mm. wide rather than 0.75 wide); tail heavily haired instead of sparsely haired; posterior ends of incisive foramina extending (in- stead of usually not ) to or beyond a line drawn between the anterior surfaces of the first upper molars; foramen ovale larger, at least 206 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. three-fourths instead of one-half the width of M3; palatal pits more deeply marked; and median keel on palate better developed. GeograpJiic Variation Tawny-bellied cotton rats were recognized by Bailey (1902) as belonging to three distinct species: S. minimus Mearns 1894, with type locality on the Mexican-New Mexico boundary and southern- most collecting locality at Casas Grandes, Chihuahua; S. ftilviventer Allen, 1889, with type locality at Zacatecas and northernmost col- lecting locality at Durango, about 800 kilometers southward of Casas Grandes; and S. melanotis Bailey 1902, with type locality at Patz- cuaro, 400 kilometers to the south of Zacatecas. Hall and Kelson (1959:676-677) retained Bailey's arrangement and noted that S. minimus was polytypic by listing subspecies named for New Mexi- can populations (also see Findley and Jones, 1963) and citing records for S. m. minimus from northern Durango, thus bridging the gap considerably between known collecting stations of S. jninimus and S. fulviventer (to about 300 kilometers — Rosario to Durango). They also reported additional collecting localities to shorten the gap between S. fulviventer and S. melanotis to about 325 kilometers (Zacatecas to Mazamitla, Jalisco). Baker and Greer (1962:121-123) concluded that S. minimus and S. fulviventer were conspecific and arranged taxa previously desig- nated as S. minitntis under the older name, S. fulviventer. My own field work in southern Zacatecas, northwestern Guanajuato, and in the vicinity of Lago de Chapala in Jalisco has provided specimens from additional collecting stations to reduce the gap between S. fulviventer and S. melanotis to less than 175 kilometers and to demonstrate that tawny-bellied cotton rats live in grassy upland habitats in more or less continuous fashion all the way south to the northern foothills of the Trans-Mexican Volcanic Belt. Since char- acters distinguishing S. melanotis from S. fulviventer (see accounts of subspecies) are, in magnitude, no greater than those distinguish- ing one subspecies of S. fulviventer from another, S. melanotis is arranged as a subspecies with the older name, S. fulviventer, being used to designate all of these tawny-bellied cotton rats. Subspecies now recognized are: Sig,moclon fulviventer fulviventer J. A. Allen, Sigmodon fulviventer goldmani Bailey, Sigmodon fulviventer mini- mus Mearns, and Sigmodon fulviventer melanotis Bailey. S. /. goldmani is not treated in the accounts beyond. Baker — Sigmodon fulviventer Group 207 Fig. 15. Geographic distribution of tawny-bellied cotton rats. 1. Sigmodon fulviventer goldmani. 2. Sigmodon fulviventer minimus. 3. Sigmodon fulviven- ter fulviventer. 4. Sigmodon fulviventer melanotis. In their study of this species (listed as the least cotton rat, Si 05 x2 CO :::o'i 1— 1 co»o 00 Tt< ^2 cio 0^ Tf CO 10 CD -t -r 3 00 u O. CO o C5 O' CO 10 Ol OcO CM CO .— 1 C-1 ^co OCO ^6 cot^ CO 01 "■^ — ' ""^ _,_^ 10 0 10 CO^ t-^ "^ J, 10 , ,-hoo CO — 1 01 in o o 03 O O fM in ■^ CD COCO CO -« CO CO r-H 05 ^H CO CO o o CT> lOCO coco CO 00 10 CO o ffl (N d_^ I — I •. o CO ^ CD 05 CD COro CO CO qa o —^ o CM a> 00 tf 00 CO dco cdt^ CO CO ick c iniS ^ in o o o o 00 CO pin in CD CO » CSl CM inco ^^. m CO (Mas CD CD OJ m in -tCO in CO CO CO roCO c^oi CO 1 CO ^H CO Jh CO CO 0 CO CO ^ ^ 0 ^ CD 00 (J t- CO t^ CO w 0 ^u 00 1 — 1 Ol r^ci CO 1 t- CD I t^ -A ^cn . — 1 oi . — 1 0 -H CD 00 o CO CO CO s o -a in Oi c« O o (M 210 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Table 4. — Result of new multiple range test on con dyloprem axillary LENGTHS OF CRANIA OF SAMPLES OF Sigmodoji fiilvivetiter. Population means ITNDERSCORED by a common line ARE not significantly DIFFERENT. Subspecies S.f. Gallego, Chihuahua fu s.f. Ivwenter s.f. melanotic S. f. minimus- S. f. melanotis Locality Coyotes, Durango Ibarra, Guanajuato La Barca, Jalisco Cross Chihuahua- Jalisco Means of condylopr maxillary lengths e- 30.7 32.5 34.0 34.8 33.9 between the samples, analysis of variance was applied to the con- dylopremaxillary lengths. The overall differences between the means of this dimension are highly significant (F=r 18.36). A new multiple range test was then made to determine the degree of dif- ference between the means from the selected localities (see Table 4). Population means underscored by a common line are not sig- nificantly different. As expected, the sample from Chihuahua (rep- resenting S. /. minimus) is significantly different from all other samples; the samples from Durango and Guanajuato (representing S. /. fulviventer) are not significantly different from each other; the samples from Guanajuato, from Jalisco (representing S. /. melanotis) and from a cross between animals from Chihuahua and from Jalisco also are not significantly different from one another. This test demonstrates that there are subspecific differences between these Mexican populations of tawny-bellied cotton rats and there is logic for arranging them under three subspecific designations. Sigmodon fulviventer minimus Mearns Sigmodon minima Mearns, Proc. U.S. Nat. Mus., 17:130, July 19, 1894. Sigmodon fulviventer minimus Baker and Greer, Michigan State Univ., Publ. Mus., Biol. Ser., 2:123, August 27, 1962. Tijpc. — Young adult male, skin and skull; no. 21187/37291 U.S. National Museum; from near Monument no. 40, 1500 m., Hidalgo Co., New Mexico, on the Mexican boundary line, 166 km. W initial monument on west bank of Rio Grande; olitained on April 26, 1892, by Edgar A. Mearns and Frank X. Holzner, original no. 1704. Range. — Elevated grasslands of southeastern Arizona, central and south- western New Mexico, northeastern Sonora, westcentral Ghihuahua and north- central Durango (.see Fig. 15). Diagnosis. — Size small for the species; dorsum intermixed with l^lack hairs and agouti-banded hairs near (c) Pinkish Buff; underparts and upper surfaces of feet and tail with this same pale coloring; base of tail slightly darker, hairs dark Pinkish Buff. No measurements of wild-taken specimens are given; con- Baker — Sigmodon fulviventer Group 211 suit Talile 3 for listing of selected measurements of laboratory-raised animals from north-central Chihuahua (Gallego). Comparisons. — To compare S. /. goldmani of New Mexico with S. /. mini- nttts, the reader may refer to the account by Findley and Jones (1963). From S. /. fitlviventci\ found directly to the southward, S. /. minimtis differs in size smaller (see Table 3); color paler (near Pinkish Bull rather than Cinnamon- Buff) both a!io\e and below; zygomatic arches noticeably wider in relation to length of skull. Remarks. — Sigmodon fuhivcnicr minimus is the smallest and palest of the Mexican tawny-bellied cotton rats. This subspecies is identifiable as far south- ward as north-central Durango where the color of specimens from near Boquil- las is almost identical to that of animals from Gallego. Specimens from near Canatlan in west-central Durango show an intermediate coloring between the paler S. /. tninimus and the darker S. /. fulviventer, but are assigned to the latter subspecies. Specimens examined (42). — Soxora: Los Nogales, 1 (US), Santa Cruz River, near Monument no. Ill, 6 (US). Chihuahua: Casas Grandes, 2135 m., 1 (US); 2 km. N Gallego, 1366 m., 2 (MSU). Duraxgo: Ro.sario, 9 (AMNH); Rio Sestin, 10 (AMNH); Guanacevi, 1 (AMNH); Rancho Bailon, 5 (AMNH); 11 km. NNE Boquilla, 1952 m., 7 (MSU). Sigmodon fulviventer fulviventer J. A. Allen Sigmodon fulviventer J. A. Allen, Bull. Amer. Mus. Nat. Hist., 2:180, October 21, 1889. Type. — Young adult male, skin and skull: no. 1975/1244 American Museum of Natural History; from Zacatecas, Zacatecas; obtained on August 17, 1889, Ijy Audley Buller, original no. 59. Range. — Grasslands on eastern foothills of the Sierra Madre Occidental from central Durango southeast\vard to western Guanajuato and southern Zacatecas (see Fig. 15). Diagnosis. — Size medium for the species; dorsum intermixed with black hairs and agouti-banded hairs of Cinnamon Bufl"; underparts and upper sur- faces of feet and tail washed with similar coloring; base oi tail darker, near ( a ) Clay Color. Average and extreme external and crania! measurements of nine wild-trapped adults (measurements compare closely with those of 100- day-old, laboratory-raised animals from the same locality, see Table 3) from Hda. Coyotes, Durango, are as follows: length of head and body, 150 ( 138-164); length of hind foot, 28 (26-30); height of ear from notch, 21.6 (20-22); con- dylopremaxiUary length, 32.5 (31.2-33.7); zygomatic breadth, 19.7 (18.8-20.6); least interorbital constriction, 4.9 (4.6-5.3); interparietal breadth, 10.8 (10.0- 11.4); depth of cranium, 10.9 (10.7-11.1); length of nasals, 12.1 (10.6-12.7); and alveolar length of maxillary toothrow, 6.5 (6.2-6.9). Comparisons. — For comparison with S. /. minimus, see account of that sub- species. From S. /. melanotis, S. f. fulviventer differs in size smaller (see Table 3); color less rich (Cinnamon-Buff rather than near (a) Clay Color) both above and below; skull less massive in appearance and less arched in the interorbital area. Remarks. — Sigmodon fulviventer fulviventer is intermediate in both size and coloration between S. /. minimus to the northward and S. /. melanotis to the 212 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. southward. There is evidence of intergradation witli the former subspecies in specimens taken near Canatlan in Durango. These are more or less intermediate in color but allocated to S. /. fulviventer. Specimens from an elevated grass- land near Ibarra in Guanajuato are paler than typical S. /. ftdvivet^ter, but in terms of size show a tendency toward the larger S. /. melanotis of nearby Jalisco. As Table 3 shows, the laboratory-raised animals from Ibarra also are more or less intermediate in size between animals from Hda. Coyotes in Durango and from near La Barca in Jalisco. Specimens examined (42). — Durango: 5 km. SE Tepehuanes, 1780 m., 1 (MSU); 9 km. NNW Canatlan, 1950 m., 2 (MSU); 4 km. SE Atotonilco, 2037 m., 1 (MSU); 5.5 km. SE Atotonilco, 2037 m., 1 (MSU); 10 km. N Durango, 2 (UI); Durango, 2 (US); Hda. Coyotes, 2475 m., 1 (CAS), 12 (MSU). Zacatecas: Laguna Valderama, 67 km. W Fresnillo, 2380 m., 5 (CAS); Zacatecas, 3 (AMNH); 13 km. S Villanueva, 2090 m., 1 (MSU). Guanajuato: 8 km. SW Ibarra, 2500 m., 9 (MSU); 12 km. SW Ibarra, 2623 m., 3 (MSU). Sigmodon fulviventer melanotis Bailey Sigmodon tnelanotis Bailey, Proc. Biol. Soc. Washington, 15:114, June 2, 1902. Type. — Adult female, skin and skull; no. 50190 U.S. National Museum; from Patzcuaro, 2135 m., Michoacan; obtained on July 15, 1892, by E. W. Nelson, original no. 2834. Range. — Mesic grasslands of the southwestern part of the Mesa Central ( southern part of the Mexican Plateau ) bordering and in the foothills of the northwestern slopes of the Trans-Mexican Volcanic Belt (see Fig. 15). Dis- tribution in grasslands and mixed agricultural country spotty, presumably be- cause of competition with S. hispidus. Diagnosis. — Size large for the species; dorsum intermixed with black hairs and agouH-banded hairs near (a) Clay Color; underparts, upper surfaces of feet and tail washed with similar rich coloring; base of tail slightly darker. No measurements of wild-taken specimens are given; consult Table 3 for selected measurements of laboratory-raised animals from Jalisco. Comparisons. — From S. /. fulviventer, which occurs directly to the north- ward, S. /. melanotis is larger and more richly colored as indicated in the accoimt of the former subspecies. Remarks. — Until now, the systematic status of S. melanotis has remained unchanged since first described by Bailey in 1902. Its rich coloring (especially conspicuous on the underparts of the specimens from Patzcuaro, Michoacan) and its characteristic "pepper and salt" dorsal appearance set it apart from other cotton rats. Moreoxer, its seemingly spotty distribution has been a deterrent to collectors. Aside from the extensive type series taken in the I890's, from the vicinity of Patzcuaro, there were no sizeable series assigned to this taxa extant, imtil members of a Michigan State University Museum field party saw a tawny-bellied cotton rat cross the road near La Barca, Jalisco, in July of 1966, and subsequently caught it and four others. In other cases (see specimens examined), only a few examples of these rats from localities in Michoacan and Jalisco occur in Mexican and American museums. The Patz- cuaro series is the richest in color; specimens from near Zamora and in the vicinity of Lago de Chapala are slightly paler ( tending in color to be closer Baker — Sigmodon fulviventer Group 213 to Cinnainon-Bufl than to Clay Color), which shows evident relationship with the more northward and paler S. /. fulviventer. Specimens assigned to the latter from Ibarra in Guanajuato also are somewhat intermediate in size between the larger S. /. melanotis and its smaller relatives to the northward. Specimens examined (18). — Jalisco: 2 km. NW La Barca, 1525 m., 1 (MSU); 2 km. N Mazamitla, 1 (UM). Michoacax: 5 km. S Cumuato, 1 (UNAM); 3 km. E La Palma, SE side Lago de Chapala, 1 (MSU); 18 km. E Zamora, 1 (TCWC); Patzcuaro, 2135 m., 12 (US). Sigmodon leucotis Siiimodon leucotis, the white-eared cotton rat, occupies montane habitats in a Y-shaped distributional pattern (see Fig. 16) from appro.ximately 25° N latitude in the Sierra Madre Occidental (in the west) and the Sierra Madre Oriental (in the east) southeast- ward into the central part of the Trans-Mexican Volcanic Belt and culminating in the Sien-a Madre del Sur in Oaxaca. This cotton rat lives in a comparable, but more mesic, habitat than does S. ochro- gnatJnis, which occupies montane areas generally northward of 25° N latitude. Hahitot and Habits The white-eared cotton rat is strictly a montane species and associated chiefly with mesic pine-oak habitat. In such areas the species seems most adapted to mixed grass and shrub cover on shal- low, rocky soils, although animals also have been taken in grassy meadows, adjacent to streams, in "sacaton" meadows, and in scat- tered clumps of bunch grass on dry, rocky slopes. The latter situa- tion is much like that preferred by S. ochrognathns, although these species ha\e never been found together where their ranges overlap (in latitude) in the Sierra Madre Occidental of central Durango. In grassy patches, S. leucotis can be taken in well-used runways, typical of other cotton rats. In low, shrub cover, runways are obscure or absent; little or no sign may be present and the detection of the presence of the species in such areas can be difficult. Such places, with exposed rocky ledges and shallow soils, often appear to be more suitable for species of Pewmyscus and Neotoma than for Sigmodon. Like S. ochrognatlius, S. leucotis does not seem to exist in such dense populations as does S. hispidus or S. fulviventer. Descriptions of collection stations are given below. Durango. — In boreal, mesic, pine-oak forest 30 km. SSW of Tepehuanes, 2500 m., two white-eared cotton rats were trapped in dense shrubs on a hill- side coxered with mixed pine, oak, man/anita, and juniper. The catches were made under clumps of Ceanothiis fendleri and scrub oak, Quercus sp. Other plants in this thicket included bunch grass {Muhlenbergia sp.), Senccio 214 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 16. Geographic distriljution of the white-eaied cotton rat. 1. Sigmodon leucotis leucotis. 2. Sigmodon leucotis alticola. actinella, and species of the genera, Geranium, Cosmos, Valeriana, CastiUcia, Achaetogeron, Lupinus, Tradescantia and Cologania. At ground level there was no e\idence of runways among the woody stems of the shruljs or at the bases of grass clumps. No burrows were found although one surface nest of grass, thought to be that of a cotton rat, was located at the base of a manzanita bush, ArctostapJu/los. The nest measured 130 mm. in circumference and 80 mm. in depth. Although no other small manunals were captured in this bushy habitat, Peromyscus hoijlii and Pcromyscus melanotis were taken in adjacent woody cover and Thomomys innbrinus, Reitlirodontomy.s megalotis, and Micro- ttis mexicanus in wet montane meadows dotted with clumps of sacaton grass. Within 3 km. of San Luis, 2300 m., S. leucotis was found in an open meadow along a cold, mountain tributary of the Rio Piaxtla (see Fig. 17). Tliis area was surrounded by boreal pine-oak, fir-aspen forest. Traps set in runways also captured Reithrodontomys megalotis and Peromyscus melanotis. Microtus mexicanus was present, but only in the open grass, whereas S. leucotis occupied the shrub zone. At Hacienda Coyotes, 2475 m., white-eared cotton rats li\ed on partly- bare, rocky slopes imder patches of low vaccinium and manzanita, just at the edge of dense pine-oak forest. No runways or cuttings were e\'ident, but holes under rock ledges were conspicuous. Traps placed in front of these holes captured most of the animals. No other small mammals were taken in associa- tion with S. leucotis, although Reithrodontomys megalotis, Sigmodon fulviven- ter, and Microtus mexicanus occupied adjacent wet meadows in bunch grasses and sacaton. Baker — Sigmodon fulviventer Group 215 Fig. 17. Riparian grass-shrub habitat surrounded by pine-fir boreal forest near San Luis, 2300 m., Durango. The Mexican vole, Microtus mexicanus, uses the open grass, whereas the white-eared cotton rat. Sigmodon Icucotis, seems to prefer the areas of mixed shrubs. Photograph taken on July 17, 1957. On a canyon side, approximately 3.3 km. N of Pueblo Nue\o, 1S30 m., a white-eared cotton rat was shot (by headlight at night) in an area of large rocks in an abandoned weedy and brushy peach orchard ( see description in Webb and Baker, 1962:328). This locality is situated on the west side of the Sierra Madre Occidental in mixed boreal-tropical habitat. Intensi\e trapping in the place where the one cotton rat was shot produced no more indix'iduals. Other mammals taken there were Thomomijs umbrinus, Peromyscus hoijlii, and Neotoma mexicana. This is the most "tropical" habitat in which S. Icucotis has been found. In southern Durango on the Rancho Las Margaritas (47 km. S and 28 km. W Vicente Guerrero, 2545 m.), S. leucotis was captured in pine-oak habitat in a narrow valley in obscure runways in scattered bunch grasses (see Drake, 1958). Other small mammals in this association were Thomomys umbrinus, Eutamias bulleii, Reithiodontomys megalotis, and Peromyscus boylii. In nearby canyon-side habitat our field party caught Peromyscus difficilis, Peromyscus truei, Neotoma mexicana, and Nelsonia neotomodon. Zacatecas. — At approximately 13 km. W of Milpillas, 2530 m., J. Dan Webster (personal communication) reported catching S. leucotis in a wet meadow surrounded by boreal pine-oak forest. At 15 km. W Zacatecas, 2135 m., white-eared cotton rats were found at a creek border in willow trees and baccharus bushes. Guanajuato. — At the Rancho La Puerta Guadalupe ( 8 km. SW Ibarra, 2500 m. ) S. leucotis occupied obscure runways in grass leading between rocks and clumps of low-growing (40 centimeters high) scrub oak (see Fig. 13). The 216 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 18. Open \alley meadow surrounded l)y oak torest near Ibarra, 2590 m , Guanajuato. The sacaton, Briza rotundata. is occupied by the white-eared cotton rat, Sigmodon leucotis, and three species of Peromyscus. Photograph taken on July 22, 1966. bunch grasses included representatives of the genera Muhlenbergia, Stipa, and Bouteloua. This location was on a sloping hillside with large oaks and manza- nita in the shallo\\' \alley below. Abo\e the slope the le\'el open grasslands were occupied by Sigmodon ftdviventer. In runways used by S. leucotis, we found grass cuttings, the husks of acorns and manzanita berries, and small piles of lily bulbs. These foods might ha\e been used by the white-eared cotton rat or by other small mammals found in the runways (Pcromijscus hoijlii, Pcromijscus maniculatus, and Pcromijscus truei). At 13 km. S Ibarra, 2590 m., S. leucotis was captured in a small meadow of about two hectares along a cold stream and surrounded entirely by an oak forest (see Fig. 18). This opening contained short grass, Piptochaetium sp., with scattered clumps of bimch grass, Muhlenbergia sp., and sacaton, Briza rotundata. Eaten-out areas at the bases of these grasses plus a few leaf cuttings were the only evidences of sign attributable to cotton rats. One cotton rat was taken in front of a hole beneath a prickly pear plant, in mixed oak and manzanita. There was no exidence that either S. fulviventer or Microtus mexi- canus were present, although the moist meadow seemed ideal for the Mexican vole. Small mammal associates in the sacaton area were Thomomys umbrinus, Peromyscus dijficilis, Peromyscus boylii, and Peromyscus truei. Morelos. — In a moist, open meadow 6.5 km. NW Huitzilac, 2800 m., one white-eared cotton rat was captured in an eaten-out area at the base of a large clump of sacaton, Muhlenbergia macroura (see Fig. 19). This clump was one of a large number that surrounded an open meadow containing such plants as Senecio pinnatisectus. Ranunculus sp., and Taraxacum officinale. Sur- Baker — Sigmodon fulviventer Group 217 rounding the meadow was a lioreal forest of pine, oak, fir, and other montane vegetation. Small mammal associates were Reithrodontomijs mef^alotis, Pcro- mysciis inelanotis, Ncotoiiiodou alstoni, and Microtus mexicantis. In the case of the latter two, both grass-eating "competitors" of the cotton rat, M. mexi- canus was most abundant in the short grass-herb meadow and N. ahtoni (see Davis and Follansbee, 1945) dominated the sacaton clumps. On the basis of these observations, S. leucotis exddently was rare and perhaps at an ecological Fig. 19. Open valley meadow surrounded by pine-fir boreal forest near Huit- zilac, 2800 m., Morelos. The open meadow is occupied by the Mexican vole, Microtus mexicanus; the \olcano mouse, Neotomodon alstoui, is the dominant grass-eating rodent in the large clumps of sacaton w here the white-eared cotton rat, Siginodon leucotis, is unconunon. Photograph taken on July 24, 1964. disadxantage. This same locality was \isited again three years later (in 1967) and the entire area was intensely live-trapped for three days, without obtaining other S. leucotis. Davis (1944:399), caught five animals in a meadow with Microtus at Monte Rio Frio in the state of Mexico, but subsequently failed to catch others. Field parties from the Michigan State Unixersity Museum also failed to find cotton rats in montane habitats in the vicinity of Oaxaca in the state of Oaxaca and in the vicinity of Pinal de Amoles in Queretaro; specimens were obtained at both places by E. W. Nelson and E. A. Goldman in the 1890's (Bailey, 1902:116). The fact that S. leucotis may live in shrub vege- tation, especially where bunch grass habitat is grazed ofi^, makes the presence of the species difficult to determine. Association of white-eared cotton rats with other species of the genus. — Sigmodon leucotis has not been taken in company with S. alleni, S. hispidtis, or S. ochrogiuithus. Perhaps S. leucotis and S. (illeni might associate in such situa- tions as foimd in the \icinity of Pueblo Xuexo in Durango where the former species has been taken in a mixed boreal-tropical habitat, not unlike some of 218 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. the places in Michoacan and Oaxaca where S. alleni occurs. In the mountains of west-central Durango, S. leucotis and S. ochrognathus occur in the same latitude (see Fig. 4) but at different elevations, with the former in higher more mesic areas and the latter on the lower slopes and foothills in arid oak- juniper areas. The two species, S. leucotis and S. ftilviventer, were found in the same areas in Durango (vicinity of Hacienda Coyotes) and in Guanajuato (8 km. SW Ibarra). At both of these places, S. ftilviventer dominates the open grass- lands whereas S. leucotis lives on the rocky, brushy, well-drained slopes. The meeting ground of these two species appears to be at the junction of these two en\ironments. In somewhat similar situations, where S. fulviventer is absent (as at San Luis and the Rancho Las Margaritas in Durango), .S. leucotis takes over both habitats. Also, S. leucotis seems to avoid extensive association with other grasseaters, Microtus mexicanus and Neotonwdon ahtoni, when S. ful- viventer is absent (as at Huitzilac in Morelos). When S. leucotis, S. fulviventer and M. mexicanus are in the same area (as at Hacienda Coyotes in Durango), S. leucotis occupies the forest-meadow ecotone (mixed brush on rocky slopes). S. fulviventer occupies the bunch grass flats, and Microtus mexicanus, although occasionally taken in runways with S. fulviventer, occupies exclusi\ely the poorly-drained parts of the montane meadow that is co^'ered with clumps of sacaton. Parasites. — Dr. Robert Traub identified the flea, Pohjgenis martinez-haezi Vargas, 1951, from S. leucotis from near Hda. Coyotes. Dr. Richard B. Loomis identified the chiggers, Hijponeocula argenicola and Fonsecia sp., from S. leu- cotis from the same area. Specific CJuiraciers and Comparisons Conspicuous whitish ears in contrast to a brownish-gray head and body together with small to medium size (for captive animals, maximum weights are 131 grams for a male and 140 for a non- pregnant female; maximum lengths of head and body are 160 mm. and 169, respectively), pronounced premaxillary depressions on each side of the rostrum, and highly reduced or absent lingual root on the first lower molar distinguish S. leucotis from other species in the S. fulviventer group, and, with the exception of size, from S. hispidus as well. Other unique characters are: anterior portion of mesopterygoid fossa parallel-sided; interparietal short, length at midline less than 2 mm.; angular process of lower jaw slightly hooked rather than rounded. The reduction or absence of the lin- gual root on the first lower molar is possibly the most distinctive character and sets this species apart as perhaps the most liighly evolved in the genus ( see also Dalby and Lille\ik, 1969 ) . From S. alleni, S. leucotis is further distinguished by skull short and broad rather than long and narrow; dorsal profile of skull more arched than flattened; upper incisors less instead of more recurved Baker — Sigmodon fulviventer Group 219 ( opisthodont ) ; auditor) bullae large instead of small in relation to size of skull; basioccipital long and narrow rather than short and wide; posterior ends of incisixe foramina extending (rather than not extending) to a line drawn between the anterior surfaces of the first upper molars; anterior lip of foramen magnum slightly instead of obx'iously notched; and paraoccipital process (from ventral view) straight rather than slightly hooked. From S. fulviventer, S. leucotis differs in color of under parts (usually whitish not buff), and in that the foramen ovale is small (no more than half width of M3) instead of large (at least three- fourths width of M3 ) . From S. ochro^^nathus, S. leucotis is further distinguished by nose usually lacking extensive, contrasting yellow coloring; auditory bullae large and broad instead of small and elongate; basioccipital long and narrow instead of short and wide; median keel on basioc- cipital slight rather than obvious; posterior ends of incisive foramina extending (rather than not extending) to a line drawn between the anterior surfaces of the first upper molars; notch on anterior lip of foramen magnum slight instead of ob\'ious; bulge of capsular projec- tions for upper incisors moderate rather than pronounced; inter- parietal without (instead of having) medium-posterior notch; and paraoccipital process (from ventral view) straight rather than curved with a basal notch. From S. hispidus, S. leucotis differs in small size of tail scales (0.5 mm. wide rather than 0.75 mm. wide); tail hea\ily haired instead of sparsely haired; skull short rather than long; palatal pits deep as opposed to shallow; and median keel on palate conspicuous rather than slight. Geographic Variation Although certain cranial and dental characters seem to set S. leucotis apart as the most distinctixe Recent species in the genus, the apparent lack of geographic \'ariation in this montane species is surprising and can be compared with the condition found in mono- typic Peromyscus melanotis, which occupies some of the same habi- tat in the same Y-shaped distributional pattern in the Sierra Madre Occidental, the Trans-Mexican Volcanic Belt (part), and the Sierra Madre Oriental. On the southward side of the watershed of the Rio Balsas, the more richly-colored S. leucotis in Puebla and Oaxaca can be easily distinguished at the subspecific level. Herein, cotton rats pre\'iously assigned to S. leucotis and to S. alticola are arranged as belonging to the same species, with the 220 Misc. Publ. 51, UiNiv. Kansas Mus. Nat. Hist. former name being adopted as the specific name because of page priority. Both species were named by Vernon Bailey in his 1902 paper with the description of S. leucotis appearing on page 115 and that of S. alticola on page 116. After examining and comparing recently-obtained material from localities in Aguascalientes and Guanajuato, which are intermediate between places from where S. leucotis and S. alticola were previously reported (see Hall and Kelson, 1959:678), it was readily evident that these montane cotton rats in central and southern Mexico belong to one species. Cotton rats of this species were obtained in abundance (as based on series in museum collections) only at a few places: in Durango near San Luis, at Hda. Coyotes, and southwest of Vicente Guerrero; in Zacatecas in the Valparaiso Mountains; in Aguascali- entes near Cerro del Jagiiey; in Guanajuato near Ibarra; in the state of Mexico at Monte Rio Frio; and in Morelos near Huitzilac. Field parties from the Michigan State University Museum either failed to obtain any or could not get adequate series of animals in numerous "likely" montane localities from west-central Durango and central Nuevo Leon south to Oaxaca, including such out-of-the-way places as Pinal de Amoles in Queretaro. Furthermore, live animals (from Hda. Coyotes and Ibarra) brought back to the MSU Museum Live Animal Colony, unlike the other species of cotton rats, produced few offspring under captive conditions. It is my opinion that this animal may be highly adapted to certain montane mixed grass and brush areas, but presumably in many such situations gives way to other grass-eating "competitors" including Microtiis mexicanus and possibly Neotomodon alstoni and S. fiilviventer. At least this is one way to explain the disjunct distribution, because on many occasions S. leucotis was not taken in places that looked almost "identical" to other sites where the animals were easily obtained. Sigmodon leucotis leucotis Bailey Sigmoclou leucotis Bailey, Proc. Biol. Soc. Wasliington, 15:115, June 2, 1902. Sigmodon alticola amoles Bailey, Proc. Biol. Soc. Washington, 15:116, June 2, 1902, type from Pinal de Amoles, Queretaro. Type. — Young adult female, skin and skull; no. 92001 U.S. National Mu- seum; from Valparaiso Mountains, 2653 m., Zacatecas; obtained on December 2, 1897, by E. W. Nelson and E. A. Goldman, original no. 11812. Range. — Montane grass-brush habitats from approximately 25° N latitude in the Sierra Madre Occidental and Sierra Madre Oriental southward to the Trans-Mexican Volcanic Belt in the states of Morelos and Mexico (.see Fig. 16). Diagnosis. — Size large for the species; dorsinu intermixed with black hairs and agouti-banded hairs, Pinkish Buff or slighth' darker, near (c) Cinnamon- Baker — Sigmodon fulviventer Group 221 .s Co ^ fc, ^S^ o ^Sg y b xj3 a (3*3 S "pSg '— ^ 1^- ,^ 5 < -c o r^ Mh a 1^ •«-rt C/3 !i S h4 < a z o H ■£ 3 0 ac U Q .Q P N o >< >, b u, O o^^ 75 S U2i H a rt H X ^*^ _ H 21^ Q J3 S o < 0) a C K« en W O < ri* J513 u «.s^ > C^ 0 •< v^^ iJ 0 »2 H Z >. U ^7313 M *- n: o i< ^o| u ^^1 c« < u M < a » H U W l; 1-1 3.S a ^ lo u pq < c-— H hJ cJ5 00 in 00 -^o -f< o lOi^ CD (N CD -H co4 Co'^t" CO CD d CD CO CO 05 CD lO -H ^ ;z; in ;z, CD 1— I 1— I o d CO CD o' CD CO 2' ^: M o^2 ic2 co^ t- 05 ::'^ 2-+. 2-^ d 1—1 CJ< o o o CO -t 1— 1 ^i6 —I in o in -t ^H G> lO t^ ino in CD in in -r •r in -V CD in -V 2 o CJ _d co2 00 00 ci f— ( d 1— H d T-H -H O 5 o m m CO CO <^ieo co^. CO CO CO CO CM 00 05 CD CO CO o CO o CO o o N CO ^ ^ o a; 3 c OS lO in co' in o d Ol ^ r o t- o •«?». d ^H ^ ^ CO '>z CO o CO sj •V CO S tc 00 05 ^^ o t- Ol CO oco CD(M 05 a> t^ CD ^d «>iin C] o\ Cl oo' CI in o CD m ^:!; 2- t- CO 00 1— 1 -r 1 -^ , -f in -r ^ cq ■-HCO ^ -T 1 — 1 1 — ( ^H -t CO -t -r -r Cl O O U o in co" CO 00 d in d d in oo' 00 05 CO d CO CO Ol in oq 00 o CO 0,05 S -I c 2 0:5 '■^ o CM >^ d" .1 CO u a cr> E -3 CO f7! o ■' c c 3 S -< s 222 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. BufF; base of tail darker; under parts whitish but sometimes washed with bufF; skull wide in interorbital area, heavily ridged, and with noticeably large audi- tory bullae. Selected external and cranial measurements are gi\en in Table 5. Comparisons. — From S. /. alticola, S. I. leiicotis differs in: size larger (see Table 5); color paler (near Pinkish Buff rather than Clay Color); imder parts usually not washed with pale buff; skull more massive, with greater width in interorbital area; auditory bullae larger; nasals broader; palatal pits deeper. Remarks. — Sigmodon leucotis leucotis is slightly larger and much paler in color than S. /. alticola from the Sierra Madre del Sur, southward of the Rio Balsas, whose watershed seems to have effectively barred the north-south passage of many mammalian species (see Baker, 1963:245). Specimens of S. /. leucotis from the northern limits of its range ( Durango, Zacatecas, Quere- taro, and Nuevo Leon) are palest (Pinkish Buff), whereas specimens from further to the south are slightly more richly colored (near Cinnamon-Buff). Sjjecimens examined (112). — Nuevo Leox: 20 km. SSW Galeana, 1891 m., 1 (CAS). DuRAXGo: 30 km. SSW Tepehuanes, 2500 m., 2 (MSU); 2.5 km. W San Luis, 2303 m., 2 (MSU); San Luis, 1 (AMNH); 1 km. E San Luis, 2.348 »i., 6 (UM), 1 (UNAM); 25 km. ENE Coyotes, 2544 m., 1 (MSU); 7 km. N from higlncaij on road to San Luis via Coyotes, 2 (CAS); 92 km. W Durango, on road to El Salto, 2407 m., 7 (CAS); Hda. Coyotes, 2477-2501 m., 4 (CAS), 8 (MSU); El Salto, 2318-2440 7n., 15 (FM), 2 (US); 3 km. N Pueblo Nuevo, 1830 m., 1 (MSU); 43 km. S and 30 km. W Vicente Guerrero, 2547 m., 9 (MSU). Zacatecas: 13 km. S Chalchuites, 2623 m., 4 (CAS); 13 km. W Milpillas (or 100 km. W Fresnillo), 2531 m., 1 (CAS); 27 km. W Mdpillas (or 112 km. W Fre.millo), 2531 m., 1 (CAS); Valparaiso Mountains, 2653 m., 10 (US); 15 km. W Zacatecas, 2135 m., 1 (CAS); 17 km. S Pinos, 2165 m., 1 (UNAM). Aguascaliextes: 5 km. N Cerro del Jagiiey, 2501 m., Sierra Fria, 15 (MVZ); Rio de San Pedro, NW side San Antonio, 1 (MVZ); 1 km. S La Labor, 1830 m., 1 (MVZ); 7.5 km. NW Calvillo, 1830 m., 1 (MVZ). Guanajuato: Puerta de Guadalupe, 2196 m., 8 km. W Ibarra, 1 (OC); J3 km. SW Ibarra, 2592 m., 1 (MSU). Queretaro: Pinal de Amoles, 2 (US). Me.xico: Monte Rio Frio, 45 km. ESE Mexico, 5 (TCWC); Hda. Cordoba, 2600 m., 1 (UM). Morelos: 4 km. N Tres Cumbres, .3202 m., 2 (TCWC); 3 km. W Huitzilac, 3050 m., 4 (TCWC); 7 km. W Huitzilac, 2806 m., 1 (MSU). Sigmodon leucotis alticola Bailey Sigmodon alticola Bailey, Proc. Biol. Soc. Washington, 15:116, June 2, 1902. Type. — Young adult male, skin and skull; no. 68231 U.S. National Museum; from Cerro San Felipe, 3050 m., Oaxaca; obtained on March 15, 1894, by E. W. Nelson and E. A. Goldman, original no. 6624. Range. — Montane grass-shrub areas in parts of the Sierra Madre del Sur of Puebla and Oaxaca (see Fig. 16). Diagnosis. — Si^e medium; dorsum intermixed with black hairs and agouti- banded hairs. Clay Color becoming more Sayal Brown on rump and at base of tail; under parts, tops of hind feet, and tail faintly washed with buff (Pale Pinkish Bufi); skull slender, lightly constructed, and with narrow interorbital space; small auditory bullae; and shallow palatal pits. Measurements are given in Table 5. Baker — Sigmodon fulvivexter Group 223 Comparisons. — For comparison wilh S. /. kitcotis, see account of that sub- species. Remarks. — Again the paucity of study material made an analysis of geo- graphic \ariati()n difficult, but this sul)species is much more richly colored tlian S. /. Icucotis. A sulnidult from near Acatzingo, Puebia, is less richly colored above but has the distinctive ])uffy wash on the underparts. The wide- spread occurrence and abundance of voles (genus Microtus) in lioreal grassy areas in Oaxaca lead me to wonder if the white-eared cotton rat in Oaxaca plays a secondary role and is highly restricted ecologically. Specimens examined (6). — Puebla: 15 km. NE Acatzingo, 1 (KU). Oaxaca: 25 km. W Oa.xaca, 2897 m., 2 (US); Cerro San Felipe, 2200 m., 2 (UM), 1 (US). Sigmodon ochrognathus Sipnodon ochrognathus, the yellow-nosed cotton rat, is the most xerophilous species in the genus. It is adapted to the dry, rocky slopes ( oak-pinon- juniper habitat) of the eastern side of the Sierra Madre Occidental from Arizona and New Mexico south to central Durango and in the widely-scattered desert ranges of the Mesa del Norte (northern part of the Mexican Plateau) in Trans-Pecos Texas, western Coahuila, northeastern Durango, and probably eastern Chihuahua (see Fig. 20). Habitat and Habits The yellow-nosed cotton rat is an inhabitant of the desert moun- tains of the American Southwest. It li\es chiefly on rocky slopes with scattered clumps of grasses, mostly in oak-juniper habitat ( see Figs. 11 and 21), although it occupies grassy montane flats in localities where other species of Sigmodon are not present. Un- doubtedly, the preferred habitat of S. ochrognathus has been altered where grazing by livestock, especially goats, has been severe. How- e\'er, this cotton rat will persist on rocky hillsides where only sparse grass occurs. Its runways are often well-marked in thick grass but are rarelv visible on bare hillsides, where the animals dart from one rock shelter to another. On several occasions animals were observed (especially in the vicinity of Boquilla, Durango) moving across such open spaces of as much as one meter in distance. Cuttings of grass blades and piles of fecal droppings are generally conspicuous; openings into burrows, many being excavated by pocket gophers (Tliomomys timbrinus), may be obscured behind or at the sides of rocks. These cotton rats will often feed at the base of a clump of grass. Since the grass droops down, it is necessary for one to raise up the dead grass to find the rat's secluded chamber, circling around the base of the clump. 224 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Fig. 20. Geographic distril^ution of the yellow-nosed cotton rat, Sigmodon ochrop.nathus. As a species, this cotton rat lives under more xeric conditions than any of the other species in the genus. Succulent plants may provide necessary moisture on dry hillsides, because it is doubtful that S. ochrognathus has much opportunity to find surface water in such well-drained situations, even if rain were more prevalent than is actually the rule in these foothills. Although no quantitative data are available, one obtains the impression that S. ochrognathiis occurs in less concentrated numbers than do other species of cotton rats. Perhaps the food supply is generally less abundant on the rocky hillsides than on deep alluvial valley soils where S. ftdvwenfer and S. luspidiis live. The seemingly lower carrying capacity of the hill- side habitat may cause yellow-nosed cotton rats to be more widely spaced in nature than other cotton rats. This suggestion is based on the fact that it is unusual to catch more than one yellow-nosed cotton rat at any one trap station, although there was no reason to indicate that the rodents did not share common runwavs. Hoffmeis- Baker — Sigmodon fulviventer Group 223 Fig. 21. Hill.side occupied by the yellow-nosed cotton rat, Sigmodon ochrogna- thiis, near Fort Davis, 1610 m., JefF Davis Co., Texas. The \egetative co\er consists of scattered shrubs of species belonj^ing to the genera Jiiiui)cnis, Rhus, and Mimosa and grasses of the genera Aiuhopogoit, Botitelotia, Miililenhcrgia, Ehjoimnis, Aragrostis, Setaria, and Panicinu. Photograph taken on August 17, 1967. ter ( 1963), who described the habits of S. ochrognathus in Arizona, found nests, usually of grass, in thickets of grasses or drooping Nolina and Agave. Captive rats sometimes made nests of cotton either inside or outside of refuge cans placed in their cages. Hoff- meister as well as Baker and Greer (1962:125) have given dimen- sions of runway systems and burrows. Descriptions of several col- lecting localities are given below. Diirango. — x\t 12 km. NNE Boquilla, 1890-1965 ni., yellow-nosed cotton rats were captured on two occasions (10 July 1965 and 8 July 1967). Most animals were taken on a north-facing slope on the eastern foothills of the Sierra Madre Occidental (see Fig. 11). The slope was rocky and covered with scattered shrubs — algerita (Mahouia trifoliata), cliff rose (Cowania mexicana), and catclaw {Mimosa sp.). Moderately-grazed chunps of tall grass of the genus Mnhlenbergia, and composites, Haplopapptis spinulosus and Baileija sp., were scattered on this hillside. Small mammal associates taken with S. ochrognathus include Perognathiis nelsoni, Reithrodontomijs fidvescens, Reithrodontomijs megalotis, and Baiomys iaylori. Sigmodon ftdviventer lived on the grassy valley floor which adjoins the hillsides. At 9 km. NNW Canatlan, 1950 m., yellow-nosed cotton rats were taken on a rocky hillside in runways through clumps of grasses, Bouteloua gracilis and Muldenhergia sp., mostly protected from grazing by thick over-head cover of Acacia, Mimosa and prickly pear (Optintia). Associated small mammals ob- tained in the area were Perognathtis nelsoni, Liomys irroratus, Thomomys urn- 226 Misc. Publ. 51, Unw. Kansas Mus. Nat. Hist. hrinus, Reithrodoniomijs fulvescens, Peronnjsctis pectoralis, Baionujs laylori, and, on adjacent flats, Si^nwdon fulviventer. Coahuila. — Baker (1956:278) found yellow-nosed cotton rats in runways in bunch grass, prickly pear, and scrub oak at 1616 meters in elevation (in the Sierra de la Madera), and in thick grass in a narrow valley floor with runs leading to burrows under small oaks at 2135 meters in elevation (in the Caiion del Hillcoat in the Sierra de la Encantada). Taylor et al. (1945:26) found cuttings, burrows, and piles of earth in grass in the Sierra del Carmen. Texas. — A north-facing, rocky hillside 3 km. NW Fort Davis, 1610 m., in Jeff Davis County (see Fig. 21) was covered with scattered cedars, Junipertis sp., and shrubs, Rhus trilohata, Rhus microphtjUa, and Mimosa sp. Yellow- nosed cotton rats were caught in obscure runways in clumps of grasses includ- ing Bonteloua gracUis, Boiiteloua curtipendula, Andropogon saccharoides, Mtih- Icnhergia spp., Ehjomirus harbictdmis, Aragrostis pilosa, and Setaria macro- stachija. Leaf cuttings, presumed to have been left in the rimways by S. ochwgnathiis, of Andropogon saccharoides, Setaria macrostachija, and Panicum sp. were identified. Small mammal associates were Perognathus nelsoni and Peromijscus pectoralis. In Brewster County, Denyes (1956) found S. ochrogna- thiis in such plant associations as sotol-sachuiste, oak chaparral, gramma-blue- stem, and feathergrass-grama. New Mexico. — Findley and Jones (1960) found S. ochrognathus in an alti- tudinal range from 1160 to 2560 meters, from the upper limits of the grassland into the pine-oak forests on rocky slopes. In higher areas this cotton rat is associated with pines, juniper and oaks; at lower elevations it lives in bunch grass, Yucca, Agave, Opuntia, and beargrass (Nohna). These authors also observed the rodents in association with plants belonging to such genera as Dasyhrion, Fouquieria, Prosopis, Mimo.m, Acacia, Arctostaphtjios, and Cero- carpus. Arizona. — Hoffmeister (1963) recorded the yellow-nosed cotton rat on grassy, rocky slopes near or within the oak belt. He listed plant associates as Quercus, Agave, Nolina, Cowanio mexicana. Mimosa hiuncifera, Opuntia, Yucca, Rhus ovata, and Dasyhrion wheeleri. The sparse cover used by S. ochrognathus included Bonteloua gracilis, Bouteloua curtipendula, Aristida sp., Heteropogon contortus, Muhlenbergia sp., Senecio longilobus, Grindelia aphanactis, and Eleocharis sp. Small mammal associates, according to Hoff- meister, were Thomomys umbrinus, Reithrodontomys fulvescens, Peromyscus hoylii, Peromyscus eremicus, and Ncotoma albigula. Association of yellow-nosed cotton rats with other species of the genus. — The yellow-nosed cotton rat occupies rocky, bunch-grass slopes from just below to within the pink-oak-juniper belt. Where it is the only cotton rat present (as in southwestern Texas and western Coahuila), S. ochrogtmthus also occurs on grassy montane "flats" or alluvial fans where deep soils and few rocks occur. In most of its range in New Mexico, Arizona, Chihuahua, and Durango, how- ever, this cotton rat is absent or occurs only peripherally in the latter habitats because these areas are occupied by S. fulviventer, although Hoft'meister (loc. cit.) found S. ochrognathus and S. hispidus at one place in Arizona. Near Canatlan, Durango, S. ochrognathus was captured in bunch grass and shrulis on a hillside slope of approximately 20 degrees, whereas S. fulviventer was trapped in more or less identical, but less rocky, cover at the base of the Baker — Sigmodon fulviventer Group 227 slope where tlie alhuial fan l)egan to le\el out. Here, the two species were not taken at the same trap stations and according to Held notes, were not trapped closer together than 18 meters. At this locality, in July of 1965, 17 S. ocIuo^natJuts and three S. fiilviocntcr were caught. The larger catch of S. ocJuo^iuitlius probably is the result of trap placement, more on the rocky slopes than on the level base. In the \icinity of Boqnilla, Durango, we also caught both species of cotton rats; S. ocJirofinatJiiis was taken on rocky, bunch- grass slopes and S. fulviventer in grassy areas on "flat" hilltops and in the deep soils of valley floors. In one narrow intermontane valley ( 3.3 km. NE Bociuilla ) containing bunch-grass, a few scattered rocks and reddish "clay" soil, I caught in one live-trap set in a nmway, one S. fulviventer on the night of 8 July 1965 and one S. ochrog.nathus the following day. Here was one instance where both species "occupied" the same nmway and were caught at the same trap station. At 12 km. NNE Boqnilla tawny-bellied cotton rats seemed entirely restricted to a grassy, hilltop flat, and yellow-nosed cotton rats occupied the rocky slopes almost entirely around the hill. Although the ranges of S. ochro^nathus and S. leucotis "overlapped" in latitude in the Canatlan-Tepehuanes area of west-central Durango (see Fig. 4), the yellow-nosed cotton rat seemed confined to the lower^ dry slopes of the foothills (no higher than 1950 meters in elevation), whereas S. leucotis occupied higher mesic areas of mixed grass, brush and rocks (at an elevation of 2500 meters), well within the montane boreal forest of the Sierra Madre Occidental. It would appear that as a species, S. ochrognathus is the cotton rat mostly highly adapted to the extreme aridity of the lower slopes of the "desert" mountains of the northern part (Mesa del Norte) of the Mexican Plateau. This kind of habitat, in the more mesic southern part (Mesa Central) of the Mexican Plateau in such states as Aguascalientes and Guanajuato, is occupied by S. leucotis. Parasite. — Dr. Robert Traub identified the flea, Pohjfienis martinez-haezi Vargas, 1951, from S. ochrognathus from near Canatlan, Durango. Specific Characters and Comparisons The drab gray dorsum contrasting with an ochraceous-colored nose and eye-ring together with small size (for captive animals, maximum weights are 130 grams for a male and 133 for a non- pregnant female; maximum lengths of head and body are 154 mm. and 149, respectively) distinguish S. ochroiinaihus from other species in the S. fulviventer group. Other uni(|ue characters in- clude: small and elongate auditory bullae; an ob\ious median keel on the basioccipital; pronounced lateral bulges of the capsular projections of the upper incisors; a median-posterior notch on the interparietal, and curxed paraoccipital processes with distinctive basal notches. From S. alleni, S. oclirognatlius further differs in having a short and broad skull rather than a long narrow one, and slightly recurved incisors rather than pronounced recurved (opisthodont) incisors. 228 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. From S. fidvive titer, S. ochrognatlnis is further distinguished by whitish instead of tawny underparts; less-arched skull; short rather than long (in relation to width) basioccipital; posterior ends of incisive foramina not extending (rather than extending) to a line drawn between the anterior surfaces of the first upper molars; anterior end of mesopterygoid fossa broad instead of narrow; an- terior lip of foramen magnum obviously notched rather than not; and foramen ovale small (no more than half width of M3) instead of large (at least three-fourths width of M3). From S. leucotis, S. ochrognatlnis is further distinguished by less- arched skull; short and broad rather than long and narrow basioc- cipital; posterior ends of incisive foramina not extending (rather than extending) to a line drawn between interior surfaces of the first upper molars; anterior end of mesopterygoid fossa expanded instead of parallel-sided; anterior lip of foramen magnum obviously notched rather than not; length at midline of interparietal more instead of less than 2 mm.; rostral depressions on sides of premaxil- laries slight rather than pronounced; angular process of lower jaw rounded instead of slightly hooked; and lingual root of first lower molar large instead of reduced or absent. From S. hispidus, S. ochrognathus difi^ers in narrower tail scales, 0.50 mm. rather than 0.75; heavily haired instead of sparsely haired tail; short and broad rather than long and narrow skull; short instead of long (in relation with width) basioccipital; less arched skull; deep rather than shallow palatal pits; and conspicuous instead of slight median keel on the palate. Geograph ic Va riatio n Yellow-nosed cotton rats have been considered as being sep- arable into three subspecies (Hall and Kelson, 1959:677-678) : S. o. madrensis Goldman and Gardner, S. o. montanus Benson, and S. o. ochrognathus Bailey. Later S. o. madrensis was placed in synonymy under S. o. hadeiji J. A. Allen, which had been previously regarded as a subspecies of S. hispidus (Baker and Greer, 1962:125). The presence of distinctive geographic variation in this species with its isolated desert-mountain populations seems at first logical, although Findley and Jones (1960), after a thorough examination of most museum specimens then extant, came to the conclusion that no significant geographic variation was discernible. They thought that the presently disjunct environment in which S. ochrognatlnis lives has not long been separated. This is in line with the findings of Baker — Sigmodon fulviventer Group 229 Wells (1966) that xerophilus woodland ( oak-pinon-juniper ) vege- tation, in which associations S. ochrognathus lives today, occurred as much as 800 meters lower in elevation perhaps 11,560 to more than 40,000 years B. P. (during the Wisconsin pluvial) than today. This would then mean that these disjunct populations have not been separated for much more than 10,000 years. Furthermore, it is likely that this xerophilus woodland maintained its continuity in the Mesa del Norte up to a postglacial period of heavy rains, per- haps between 6210 and 7756 B.P. (Findley and Jones, 1960:468), and that the present disjunct montane distribution may have re- sulted from ensuing desiccation after the above dates. Findley and Jones felt that the disjunct habitat of S. ochrognathus may be so newly developed that isolation has not been long enough to allow for a discernible degree of geographic variation. Relying in part on the findings mentioned above and in part on study of material from Durangan localities from which S. ochrognathus lias not been reported previously, I am inclined to consider yellow-nosed cotton rats, for the present, as belonging to a monotypic species. Sigmodon ochrognathus Bailey Sifimodon ochroffiiafliiis Bailey, Proc. Biol. Soc. Washington, 15:115, June 2, 1902. Sigmodon baileyi J. A. Allen, Bull. Amer. Mus. Nat. Hist., 19:601, November 12, 1903, type from La Cienega de las Vacas, 2990 m., Durango. Sigmodon ochrognaihus montanus Ben.son, Proc. Biol. Soc. Washington, .5.3:1.57, December 19, 1940, type from Peterson's Ranch "Sylvania"), 1860 m., 3 km. N Sunnyside, Huachuca Mts., Cochise Co., Arizona. Sigmodon ochrognathus madrensis Goldman and Gardner, Jour. Mamm., 28:58, February 17, 1947, type from foothills of Sierra Madre Occidental, 50 km. NW Parral, 1890 m.. Chihuahua. Table 6. — Selected measurements (averages and extremes) of wild- caught AND OF laboratory-raised (100 DAYS OLD ) Signiodon ochrognathus. 9 km. NXW Canatlan, .3 km. NE Boquilla, ,, . Durango Durango Measurement (8 specimens, (6 specimens, wild-taken) laboratory-raised) Length of head and body 1.39 (1.32-144) 1.38(1.30-144) Length of hind foot 28 (25-29) 29 (29-30) Height of ear from notch 21 ( 20-22 ) 19 ( 18-19 ) Condvlopremaxillary length 31.2(30.2-32.0) 29.4(28.6-30.1) Zygomatic breadth 18.7 (18.3-19.4) 18.1 (17.6-18.4) Least interorbital constriction 4.8 (4.6-4.9) 4.8 (4.6-5.1) Depth of cranium* 10.0(9.6-10.3) 9.5(9.4-9.7) Length of nasals 11.7 (11.0-12.5) 11.5 (11.2-12.1) Alveolar length of max. toothrow 6.3 (6.1-6.4) 6.1 (6.0-6.2) Measurement taken as described by Findley and Jones (1963:308). 230 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Type. — Young adult female, skin and skull; no. 110333 U.S. National Museiun; from Chisos Moimtains, 2840 m., Brewster Co., Texas; obtained on June 13, 1901, by Vernon Bailey, original no. 7681. Range. — Montane habitats, mostly arid, rocky, bunch-grass-covered slopes in pinon-oak-juniper in southern Arizona, southwestern New Mexico, Trans- Pecos Texas, Chihuahua, Coahuila, and Durango (see Fig. 20). Diagnosis. — See account of specific characters and comparisons. Remarks. — In Talkie 6 are presented selected external and cranial measure- ments of young adult, wild-taken specimens and of laboratory-raised, 100- day-old specimens, all from Durango. The two samples originated from localities approximately 175 km. apart. The 100-day-old individuals are smaller and less mature than the wild-taken sample, the latter judged to be almost adult. Specimens examined (41). — Chihuahua: near Parral, 1890 m., 1 (US). Coahuila: Tinaja de Telles, 1464 m.. El Jardin Ranch, Sierra del Carmen, 1 (TCWC); Juarez Caiwn, 1464 m., Sierra del Carmen, 16 (DMNH), 3 (US); 33 km. S and 7 km. W Ocampo, 1616 m., 3 (KU). Durango: Rancho San- tuario, 4 (AMNH); La Cienega de las Vacas, 1 (AMNH); Arroyo de Bucij, 1 (AMNH); 11 km. NNE Boquilla, 1952 m., 2 (MSU); 2 km. NE Boquilla, 1890 ;»., 1 (MSU); 3 km. NE Boquilla, 1952 m., 2 (MSU); 9 km. NNW Canatlan, 1950 m., 11 (MSU); 2 km. ESE Atotonilco, 2043 m., 1 (MSU). Other records. — Chihuahua: 5 km. SW Pacheco; 13 km. NE Laguna, 2211 m.; 3 km. W Minaca, 2104 m.; Cherry Ranch, 18 km. NW Cocomorachi (Findley and Jones, 1960:468). Duraxgo: Guanacevi (Baker and Greer, 1962:126). Literature Cited Allen, J. A. 1906. Mammals from the states of Sinaloa and Jalisco, Mexico, collected bv J. H. Battv during 1904 and 1905. Bull. Amer. Mus. Nat. Hist., 22:191-262, pis. 20-23. Anderson, S. 1959. Distribution, variation, and relationships of the montane vole, Microtus montanus. Univ. Kansas Publ., Mus. Nat. Hist., 9:415- 511, 12 figs. Bailey, V. 1902. Synopsis of the North American species of Sigmodon. Proc. Biol. Soc. Washington, 15:101-116. Baker, R. H. 1956. Mammals of Coahuila, Mexico. Univ. Kansas Publ., Mus. Nat. Hist., 9:125-335, 75 figs. 1963. Geographical distribution of terrestrial mammals in Middle America. Amer. Midland Nat., 70:208-249, 1 fig. 1966. Further notes on the manmials of Durango, Mexico, four. Nhunm., 47:344-345. Baker, R. H., and J. K. Greer 1962. Mammals of the Mexican state of Durango. Michigan State Univ., Publ. Mus., Biol. Ser., 2:25-154, 4 pis., 6 figs. Baker, R. H., and C. J. Phillips 1965. Mammals from El Ne\'ado de Colima, Mexico, four. Mamm., 46: 691-693. Baker, R. H., and D. Woxiochel 1966. Mammals from southern Oaxaca. Southwest. Nat., 11:306. Baker — Sigmodon fulviventer Group 231 Blaih, W. F. 1958. Distributional patterns of vertebrates in the soutliern United States in relation to past and present en\'ironments. Pp. 433-468 in Zoo- geography (C. L. Hubbs, ed.), AAAS Publ., 51:.x + 509 pp., ilhistrated. Chipman, R. K. 1965. Age determination in the cotton rat (Sigmodon hispidiis). Tulane Studies Zool., 12:19-38, 15 figs. COCKRUM, E. L. 1948. The distribution of the hispid cotton rat in Kansas. Trans. Kansas Acad. Sci., 51:306-312, 3 figs. CoHx, T. J. 1965. The arid-land katydids of the North American genus Neohancttia (Orthoptera: Tettigoniidae ) : their systematics and a reconstruction of their history. Misc. Publ. Mus. Zool., Univ. Michigan, 126:1-179, frontispiece, 24 figs. Dalijy, p. L., and H. a. Lillevik 1969. Taxonomic analysis of electrophoretic blood serimi patterns in the cotton rat, Sigmodon. Michigan State Univ., Publ. Mus., Biol. Ser., 4:65-104, 4 pis., 11 figs. Davis, W. B. 1944. Notes on Mexican mammals, jour. Mamm., 25:370-403. Davis, W. B., axd L. A. Follaxsbee 1945. The Mexican volcano mouse, Neotomodon. Jour. Mamm., 26:401- 411. Denyes, H. a. 1956. Natural terrestrial communities of Brewster County, Texas, with special reference to the distribution of the mammals. Amer. Mid- land Nat., 55:289-320, 3 figs. DiLLOX, L. S. 1956. Wisconsin climate and life zones in North America. Science, 123: 167-176, 13 figs. DOHAN, D. J. 1955. A catalogue of the Protozoa and helminths of North American rodents. III. Nematoda. Amer. Midland Nat., 53:162-175. Drake, J. J- 1958. The brush mouse Peromijscus hoijlii in southern Durango. Michigan State Univ., Publ. Mus., Biol. Ser., 1:97-132, 3 pis., 8 figs. FiXDLEY, J. S. 1954. Competition as a possible limiting factor in the distribution of Microtus. Ecology, 35:418-420, 1 fig. FiXDLEY, J. S., AXD C. J. JOXES 1960. Geographic \ariation in the yellow-nosed cotton rat. Jour. Mamm., 41:462-469, 1 fig. 1962. Distribution and \ariation of \oles of the genus Microtus in New Me.xico and adjacent areas. Jour. Mamm., 43:154-166, 5 figs. 1963. Geographic variation in the least cotton rat in New Mexico. Jour. Mamm., 44:307-315, 9 figs. Goldman, E. A. 1951. Biological investigations in Mexico. Smithson. Misc. Coll., 115:.\iii + 476 pp., frontispiece, 70 pis., 1 map. Goodwin, G. G. 1955. Three new cotton rats from Tehuantepec, Mexico. Amer. Mus. Novit., 1705:1-5. Hall, E. R., and K. R. Kelsox 1959. The mannnals of North America. Ronald Press Co., New York. 2:\iii + 547-1083 + 79 pp., figs. 313-553, maps 321-500. 232 Misc. Publ. 51, Univ. Kansas Mus. Nat. Hist. Hall, E. R., and B. Villa-R. 1949. An annotated check list of tlie mammals of Michoacan, Mexico. Univ. Kansas Publ, Mus. Nat. Hist., 1:431-472, 2 pis., 1 fig. Hershkovitz, p. 1962. Evolution of Neotropical cricetine rodents (Muridae) with special reference to tlie phyllotine group. Fieldiana: Zool., 46:1-524, frontispiece, 123 figs. 1966. Mice, land l)ridges and Latin American faunal interchange. Pp. 725- 751 in Ectoparasites of Panama (R. L. Wenzel and V. J. Tipton, eds.). Field Mus. Nat. Hist., xii + 861 pp., 93 pis., 154 figs., 1 map. HiBBARD, C. W. 1960. An interpretation of Pliocene and Pleistocene climates in North America. 62nd Ann. Rep., Michigan Acad. Sci., Arts, Letters, 1959-60, pp. 5-30, 2 figs. HOFFMEISTER, D. F. 1963. The yellow-nosed cotton rat, Sigmodon ochrognathus, in Arizona. Amer. Midland Nat., 70:429-441, 7 figs. Hooper, E. T. 1955. Notes on mammals of western Mexico. Occas. Papers Mus. Zool., LTniv. Michigan, 565:1-26. 1961. Notes on mammals from western and southern Mexico. Jour. Mamm., 42:120-122. 1962. The glans penis in Sigmodon, Sigmomys, and Rcitlirodon ( Roden- tia, Cricetinae). Occas. Papers Mus. Zool., Univ. Michigan, 625: 1-11, 2 figs. Jones, J. K., Jr. 1964. Distribution and taxonomy of mammals of Nebraska. Univ. Kansas Publ., Mus. Nat. Hist., 16:1-356, pis. 1-4, 82 figs. Leopold, A. S. 1959. Wildlife of Mexico the game birds and mammals. Univ. California Press, Berkeley and Los Angeles, xiii + 568 pp., 194 figs., illustrated. Meyer, B. J., and R. K. Meyer 1944. Growth and reproduction of the cotton rat, Sigmodon liispidiis hispidus. under laboratory conditions. Jour. Mamm., 25:107-129, 2 pis. Mohlhenrich, J. S. 1961. Distribution and ecology' of the hispid and least cotton rats in xNew Mexico. Jour. Mamm., 42:12-24, 3 figs. Odum, E. p. 1955. An ele\'en year history of a Sigmodon population. Jour. Mamm., 36:368-378, 1 pi, 4 figs. Ridgway, R. 1912. Color standards and color nomenclature. Privately printed, Wash- ington, D.C., iii -f 43 pp., 53 colored pis. Slaughter, B. H. 1966. The Moore Pit local famia; Pleistocene of Texas. Jour. Paleont., 40:78-91, 6 figs. Taylor, W. P., W. B. McDougall, C. C. Presnall, and K. P. Schmidt 1945. Preliminary ecological sur\ey of the northern Sierra del Carmen, Coahuila, Mexico. Mimeo., 48 pp., 16 figs., 1 map. Webb, R. C, and R. H. Baker 1962. Terrestrial vertebrates of the Pueblo Nuevo area of southwestern Durango, Me.xico. Amer. Midland Nat., 68:325-333, 1 fig. Wells, P. V. 1966. Late Pleistocene vegetation and degree of pknial climatic change in the Chihuahuan Desert. Science, 153:970-975, 2 figs. CONE CACHES AND MIDDENS OF TAMIASCIURUS IN THE ROCKY MOUNTAIN REGION BY Robert B. Finley, Jr. The red squirrel (Tamiasciurus hudsonicus) of the Rocky Moun- tain region is an animal of the coniferous forests. Its conspicuous middens of cone debris are easily recognized throughout the Rocky Mountains from Alaska to Arizona. In this \ast region deciduous hardwood forests are of minor extent and Httle importance as pro- ducers of food for squirrels. Tamiasciurus is well adapted to these conditions and is able to subsist on almost any of the conifer seed crops that may be a\'ailable. In the West, red squirrels are able to survi\'e a winter of complete cone crop failure (M. C. Smith, 1968) but rarely, if ever, occupy hardwood stands without conifers. In the eastern United States and adjacent Canada red squirrels are likewise primarily dependent on conifer seed crops, but they also make considerable use of hardwood mast where available and are able to exist in some deciduous forests without conifers (Hatt, 1929:43). As to be expected of a species so wide ranging, the red sc^uirrel has a wide adaptability to different habitats and food supplies. It is not known to what extent this adaptability represents genetic dif- ferences between populations and to what extent it is behavioral response to one environmental condition or another. Much informa- tion has been published on the life history and behavior of red squirrels of the northeastern (Klugh, 1927; Hatt, 1929; Layne, 1954) and northwestern (Shaw, 1936; C. C. Smith, 1968) United States. Because much less has been reported for the Rocky Moun- tain region, a contribution to knowledge of red squirrel habitat relations is presented here. The caching habit of red squirrels has long been known and exploited in the West by foresters and nurserymen as a source of conifer seeds for planting (Cox, 1911:17). It is usually the cheapest source for large quantities of seed of the commercially and horti- culturally desirable spruce, fir, and pine trees, and the seeds thus harvested have high \iability ( Lavender and Engstrom, 1956 ) . However, some timber managers accuse the squirrels of harvesting such a high percentage of cones of certain species as to prevent (233) 234 Misc. Publ. 51, Uxiv. Kansas Mus. Nat. Hist. adequate natural forest regeneration. Inasmuch as there seems to be Httle information in the hterature on the economic status of Tamiasciurus in the Rocky Mountains, some observations on this aspect are also given. This paper is based on examination of sexeral hundred middens and caches of Tamiasciurus hudsonicus fremontii, T. li. mogoUonen- sis, and T. h. richardsoni in Colorado, northern Arizona, and western Montana in the period 1963 to 1968. Approximately 60 of these were excavated for cone caches, and 34 of the more noteworthy middens were described in some detail. Many of the middens in the Front Range of Colorado were examined repeatedly in different years. Much general information was gained from Harrx' M. Swift, nurseryman and owner of Colorado Evergreens, Inc., of Golden, Colorado, who has had many years of experience collecting and marketing conifer seeds from squirrel caches in Colorado. I am indebted to Curtis H. Halvorson for many stimulating discussions of his red squirrel studies in Montana and for reviewing a draft of this paper. William B. Finley, U.S. Forest Service, first acquainted me with the remarkably productixe cone caches on the Kaibab Plateau. Characteristics and Variation of Middens and Caches The importance of conifer seed in the diet of the red squirrel is strikingly evident to anyone who examines one of the great midden heaps under a dense, shady stand of blue spruce (Picea pungens) alongside a mountain stream in Colorado. The larger middens are freciuently 20 to 30 feet across, one to one and a half feet deep in the center, and carpet the ground to the exclusion of all living plants. The surface is usually littered with fresh cone scales and cores dropped by the squirrels. The material below is loose and damp, easily dug into with the bare hands. As one digs into the deeper deposits the material at lower lexels is found to be older and more decomposed, forming a rich mulch in contact with the mineral soil. Large middens must be decades old and represent the accumula- tions of many successive generations of red squirrels. Such a mid- den is an example of ecological homeostasis, for its owner can easily store in it a much larger supply of food in good condition than a squirrel could store under a similar tree stand not previously oc- cupied by red scjuirrels. Cache holes are much harder to dig in soil and the cones dry out (juicker if not covered with cone litter. FiNLEY — Cone Caches of Tamaisciurus 235 The continuing utility of such a long-used midden is illustrated by a medium-sized one I saw in 1963 under a recently dead spruce tree 57 feet tall near Corral Park, 8600 feet, in the Rio Grande National Forest, Colorado. The midden was exposed in the sunlight but still in use by the squirrel chattering from a dead limb above. Almost five years later the midden was still acti\e, as evidenced by an accumulation of fresh cone scales and cores of blue spruce around the base of the dead tree. The midden, on a north-facing slope, was still damp below a depth of three inches in mid-June. Sparse grasses and blooming red columbines (Aquilegia elegantula) were growing on its outer portion. There was a grass nest about 30 feet high in a live blue spruce standing 20 feet upslope from the dead tree. Active middens remain fairly loose, with fresh or discolored cone scales and cores on the surface, but old inactive middens become mixed with needle litter, compacted, weathered, and decomposed. Abandoned middens eventuallv become covered with a laver of forest duff; if exposed to some sunlight, they gradually become coxcred o\'er with encroaching grasses, forbs, mosses, kinnikinnick (Arctostapljylos tivo-tirsi), or low shrubs. Kinds of Cones Cached Although cones of nearly all species of needle-leaved trees in Colorado are cached for food, there are differences in preference. In general, red squirrels seem to prefer cones of blue and Engel- mann spruce (Picea en