84 



NORTH AMEEICAN FAUNA. 



[ NO. 39. 



form of the fulvits group, with a range corresponding to that of the 

 creosote bush in the Detrital and Big Sandy Valleys, and extending 

 well up into the Grand Canyon. 



Specimens examined.— TotsA number, 34, as follows: 



Arizona: Big Sandy Creek (at 2,000 feet altitude), 7; Dolans Spring, 7;^ Grand 

 Canyon (at 4,500 feet in lower end of Prospect Valley on Hualpai Indian 

 Reservation), 4; Little Meadows (in Sacramento Valley), 2; Mineral Park, 

 3; 1 Mud Spring, 8; ^ Willow Spring, 3.^ 



THOMOMYS FULVUS INTERMEDIUS Mearns. 

 Mountain-Top Pocket Gopher. 



(PL VI, fig. 5.) 



Thomomys fulvus intermedius Mearns, Proc. U. S. Nat. Mus., XIX, 1897, 719, July 30, 

 1897. 



Type. — Collected on summit of Huachuca Mountains (9,000 feet 

 altitude) southern Arizona, by F. X. Holzner, September 6, 1893. 

 Type specimen in U. S. Nat. Mus. 



Distrihution. — Upper slopes of mountains in southeastern Arizona 

 and extreme southwestern New Mexico (fig. 8). 



Characters. — Smaller than fulvus, with conspicuous black back 

 and bright brown sides; skull small and slender; ears and claws 

 medium; mammse in 4 pairs, inguinal 2-2, pectoral 2-2. 



Color. — Upperparts dark tawny shading into black along the back 

 from nose to tail, in some specimens forming a broad and clear black 

 band and in others indistinct and brownish black; underparts pale 

 tawny; tail brown, with whitish tip; feet soiled whitish. May, August, 

 and September specimens show practically the same coloration. 



Slcull. — Small and slender; zygomata very slender and strictly 

 parallel ; nasals narrow, deeply emarginate ; bullae small and flattened ; 

 basioccipital triangular; pterygoids thickened at base and with 

 narrow fossa; interparietal small and generally triangular. Denti- 

 tion light. 



Measurements. — ^Type ( c? ad.): Total length, 200; tail vertebrae, 

 66; hind foot, 26. Adult male, from Fort Huachuca: 200, 59, 27. 

 Adult female from Fort Huachuca: 198, 62, 25. Slcull (of type): 

 Basal length, 34; nasals, 13; zygomatic breadth, 22; mastoid 

 breadth, 18; interorbital breadth, 7; alveolar length of upper molar 

 series, 6.5. 



Remarlcs. — This small, black-backed form of the fulvus group has 

 a wide and scattered range with considerable variation on the different 

 mountains. On top of the Chiricahua Mountains it is a little larger 

 than typical; on the crest of Animas Peak, a little smaUer; on the 



iln Detrital Valley. 



