102 



NORTH AMEEICA^T FAUNA. 



[no. 39. 



Color. — Summer pelage: Practically the same as in clusius, with 

 less gray on cheeks; upperparts light huffy- or hazel-gray, brightest 

 on crown; ear patch blackish; underparts huffy, sometimes with 

 white on chin; feet and tail whitish. Winter pelage (November 

 specimen, from Fort Custer) : Upperparts much paler, light huffy 

 gray; underparts creamy white. 



SlcuU. — Size and general form nearly as in talpoides, but less ridged 

 and with smaller molars, much larger and more rounded bullae, and 

 narrower anterior shaft of basioccipital. 



Measurements. — Type (j ad.): Total length, 238; tail vertebrae, 

 72; hind foot, 30. Male topotype: 242, 76, 30; female topotype: 

 225, 78, 29. SJcull (of type): Basal length, 37.6; nasals, 15.5; zygo- 

 matic breadth, 24; mastoid breadth, 20.3; interorbital breadth, 6.5; 

 alveolar length of upper molar series, 8. 



Remarlcs. — This is a pale Upper Sonoran form, not entirely inter- 

 mediate between talpoides and clusius, both of which are Transition 

 Zone forms (one of the humid grass-prairies, the other of arid sage- 

 brush). To some extent huUatus combines the characters of both, 

 but is not cjuite intermediate and has a well-defined range. The 

 beautiful series of specimens from Medicine Hat, Alberta, mainly 

 immature females, are in the light gray, early winter coat. They are 

 provisionally placed with this form until better characters can be 

 observed from skulls of adult males and from summer skins. 



Specimens examined. — Total number, 82, as follows: 

 Alberta: Medicine Hat, 10 (not typical). 



Montana: Alzada, 1; Cedar Creek (15 miles north of Terry), 3; Darnalls (on south 



bank Missouri River south of Glasgow), 1; Fort Assiniboine, 4; Fort Custer, 6; 



Fort Thorne, 1; Johnson Lake, 2; Piney Buttes, 2; Powderville, 4; Red 



Lodge, 1; Terry, 1. 

 North. Dakota: Buford, 4; Yellowstone River (mouth), 1. 

 South Dakota: Buffalo Gap, 3; Corral Draw (Pine Ridge Indian Reservation), 



4; Crow Buttes (Harding County), 1; Elk Mountain, 10; Fort Meade, 1; 



Rapid City, 2; Smithville, 2. 

 Wyoming: Clearmont, 1; Devils Tower, 1; Ishawooa Creek, 4; Moorcroft, 3; 



Newcastle, 5; Powder River crossing, 2; Sage Creek (west of Fort Washakie), • 



1; Wind River (north of Washakie), 1. 



THOMOMYS TALPOIDES NEBULOSUS Bailey. 

 Black Hills Pocket Gopher. 

 (PI. vn, fig. 3.) 



Thomomys talpoides nehulosus Bailey, Proc. Biol. Soc. Washington, XXVII, 116, July 

 10, 1914. 



Type. — Collected in Sand Creek Canyon, Black Hills, Wyoming 

 (at Jack Boyden's ranch, 5 miles above mouth of Canyon, at 3,750 feet 

 altitude), by Vernon Bailey, August 25, 1913. Type specimen in 

 U. S. Nat. Mus., Biological Survey collection. 



