44 



NORTH AMEEICAN FATJE^A. 



[no. 39, 



THOMOMYS TOWNSENDI NEVADENSIS Merriam. 

 Nevada Pocket Gopher. 



(PL III, fig. 3.) 



Thomomys nevadensis Merriam, Proc. Biol. Soc. Washington, XI, 213, 1897. 



Type. — Collected at Austin, Nevada (exact locality, bottom of 

 vaUey about 5 miles west of the town in moist soil near Reese 

 River) by Vernon Bailey, November 11, 1890. Type specimen in 

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



Distribution. — VaUeys of central and northern Nevada and south- 

 eastern Oregon, from Austin and Lovelocks, Nev., north to Alvord 

 Lake, Oreg. (fig. 5). 



Characters. — Size large; hind foot 35-40 mm.; skull heavily ridged 

 and angular with projecting incisors; colors dichromatic, buffy gray, 

 or black; in the gray phase more buffy and in the black phase more 

 plumbeous than in townsendi; mammae in 4 pairs, inguinal 2-2, 

 pectoral 2-2. 



Color. — In gray phase: Light buffy gray, shghtly paler on belly, 

 feet, and tail; nose and cheeks plumbeous; throat white. In black 

 phase: Bluish black or plumbeous all over except white throat 

 and usually white feet. There is often a small white spot on top 

 of head and the white throat patch extends to breast on some speci- 

 mens. Intermediate specimens are bluish gray or mixed gray and 

 plumbeous. 



Slcull. — Heavy and angular with long nasals and rostrum; lateral 

 ridges joined in sagittal crest in old males; zygomatic arches wide 

 spreading with slight median constriction; bullae large but depressed 

 to plane of basioccipital and with sharp anterior points; basi- 

 occipital narrowed between bullae; pterygoids high, thin, and arched. 

 Dentition heavy; incisors slightly projecting; inner groove obscure. 



Measurements. — Type ( c? ad.): Total length, 275; tail vertebrae, 

 90; hind foot, 38. Topotype ( ? ad.): 255, 82, 35. SJcull (of type): 

 Basal length, 44; nasals, 15.5; zygomatic breadth, 31; mastoid 

 breadth, 26; alveolar length of upper molar series, 9. 



Remarlis. — None of the type series are in the black phase, but 

 in a series of 15 from Battle Mountain 7 are black, 5 are gray, and 

 3 are intermediate. Other melanistic specimens come from HaUeck, 

 Argent a, Winnemucca, and McDermitt, Nev., and Lake Alvord, Oreg. 

 Like townsendi, this gopher inhabits moist fertile valley bottoms and 

 not the surrounding dry sagebrush land. Its range therefore is along 

 stream valleys, and while its close relationship with townsendi indi- 

 cates only subspecific rank, its range is apparently at present not 

 continuous with that form. On the west it is cut off from its next 

 nearest relative^ — griseus — by the Sink of the Humboldt and its desert 

 margins. 



