1915. ] 



THOMOMYS TALPOIDES GROUP. 



103 



Distrihution.—BlsiGk Hills, S. Dak., and Bear Lodge Mountains, 

 Wyo. (fig. 10). 



Characters. — Size of talpoides; color more brownish gray; skull 

 slender, lightly ridged; dentition light; bullae well rounded; not 

 very different externally ivomfossor, but mammae in 6 pairs, inguinal 

 2-2, abdominal 2-2, pectoral 2-2. 



Color. — Summer pelage (July and August): Upperparts dull gray- 

 ish brown; nose plumbeous or dusky; ear patch blackish; underparts 

 buffy, generally with white on chin and sometimes on breast; feet 

 and tail whitish gray or buffy. Winter pelage (held over in April 

 specimens from Redfern, S. Dak.) : Dark buffy gray, darker than in 

 similar coat of talpoides, not so rufescent as in fossor; underparts 

 light buff. Young (half -grown July specimen from Custer, S. Dak.) : 

 Dull and dark, as in talpoides. 



Slcull. — Larger and more heavily ridged than in talpoides but less 

 heavily ridged than in rufescens; temporal ridges parallel in adults, 

 and interparietal triangular; audital bullas full and well rounded but 

 not so large as in huUatus; basioccipital slender. Dentition conspicu- 

 ously light. Compared with fossor, the skull is larger, relatively 

 wider, and more robust. 



Measurements. — Type: Total length, 230; tail vertebrae, 66; hind 

 foot, approximately 32 (27 without toenails). Average of 4 female 

 topotypes: 226, 65, 31.5. Slcull (of type): Basal length, 37.7; nasals, 

 14.3; zygomatic breadth, 24.3; mastoid breadth, 20; interorbital 

 breadth, 6.5; alveolar length of upper molar series, 7.7. 



Remarlcs .—Thi^ is a well-marked form of talpoides, occupying the 

 higher parts of the Black Hills and Bear Lodge Mountains, and 

 coming down in wooded canyons to the base of both ranges in the 

 Canadian and Transition Zones. In the Bear Lodge Mountains it is 

 less strongly differentiated from talpoides and shows a tendency to- 

 ward hullatus, but can best be placed with the Black Hills form. 



Specimens examined. — Total number, 27, as follows: 

 South Dakota: Beaver Creek, 1; Custer, 4; Redfern, 4; Spring Creek, 1; Ti- 

 gerville, 2. 



Wyoming: Bear Lodge Mountains (at 6,000 and 6,200 feet altitude), 6; Rattle- 

 snake Creek (head, at 6,000 feet in the Black Hills), 2; Sand Creek Canyon, 5; 

 Sundance (in canyon at base of Bear Lodge Mountains), 2, 



THOMOMYS TALPOIDES CARYI Bailey. 

 Bighorn Pocket Gopher. 



(PI. VII, fig. 6.) 



TTiomomys talpoides caryi Bailey, Proc. Biol. Soc. Washington, XXVII, p. 115, July 

 10, 1914. 



Type. — Collected at head of Trapper Creek, at 9,500 feet altitude, 

 in the Bighorn Mountains, Wyoming, by Merritt Cary, July 10, 1910. 

 Type specimen in U. S. Nat. Mus., Biological Survey collection. 



