60 



NOETH AMEEICAK FAUHA. 



Tno. 39. 



THOMOMYS BOTT.E ALTICOLUS Allen. 

 Sierra Laguna Pocket Gopher. 



(PL IV, fig. 8.) 



Thomomys fulvus alticolus Allen, Bui. Am. Mus. Nat. Hist., XII, 13, Apr. 4, 1899. 



Type. — Collected at Sierra Laguna, Lower California, Mexico 

 (altitude 7,000 feet), by Dane Coolidge, July 10, 1896. Type specimen 

 in British Museum. 



Distribution. — Victoria Mountains, southern Lower California (fig. 7) . 



Characters. — Size and proportions of anitx or slightly smaller; 

 well furred and dark colored; skull slightly slenderer than in anitse, 

 but very similar; mammae in 4 pairs. 



Color. — Winter pelage: Upperparts dark ochraceous or snuff brown, 

 heavily clouded with dusky, usually darkest along median line of 

 back; nose, ear patch, and cheeks blackish; underparts washed with 

 bright ochraceous-tawny ; lining of cheek pouches, feet, and tip of 

 tail usually whitish. Summer pelage: Clear ochraceous, scarcely 

 darker above than below, or varying to almost black in specimens 

 with a strong tendency toward dichromatism. 



Slcull. — Slightly slenderer than that of anitx, less slender than in 

 typical nigricans, and with larger bullae, wider occiput, and wide 

 premaxillse. 



Measurements. — ^Average of 5 topotypes ( c? ad.): Total length, 

 225; tail vertebrae, 72; hind foot, 30. Average of 5 topotypes ( $ ad.) : 

 203, 67, 28. Slcull (of topotype, c? ad.) : Basal length, 38; nasals, 13.5; 

 zygomatic breadth, 24; mastoid breadth, 20; interorbital breadth, 

 6.5; alveolar length of upper molar series, 8.5. 



Remarries. — This is a dark, mountain form of anitse from the higher 

 zone of nut pines and oaks. The two forms are so closely related 

 that the skulls are practically indistinguishable, but the skins greatly 

 differ in color. Compared with nigricans, the skins are scarcely dis- 

 tinguishable, but the skulls are strikingly different. 



Specimens examined. — Total number, 52, as follows: 

 Lower California (southern): La Laguna, 20; Victoria Mountains, 32. 



THOMOMYS BOTT^ RUSSEOLUS Nelson & Goldman. 

 San Angel Pocket Gopher. 



(PI. IV, fig. 9.) 



Thomomys hottm russeolus Nelson & Goldman, Proc. Biol. Soc. Washington, XXII, 25, 

 Mar. 10, 1909. 



Type. — Collected at San Angel, Lower California, at 100 feet 

 above sea level, by E. W. Nelson and E. A. Goldman, October 15, 1905. 

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



1 No. 146836, U. S. Nat. Mus. 



