56 



NORTH AMEEICAN FAUNA. 



[no. 39. 



Distribution. — Carrizo Plain, Cal. (fig. 6). 



Characters. — Size large, about as in hottx; color pale, belly buff or 

 whitish; skull similar to that of hottse, but with smaller molars. 



Color. — Summer pelage (May specimens): Upperparts dull ochra- 

 ceous-buff, paler than in angularis or pascalis; nose brownish; ears 

 blackish; underparts pale buffy or whitish (one specimen with almost 

 pure white belly) ; feet and tail white. 



SlcuU. — Very similar to that of hottse but with conspicuously 

 smaller molar crowns and smaller bullae. The narrow skull and pro- 

 jecting incisors readily separate this race from angularis or pascalis, 

 while the projecting incisors and shorter braincase distinguish it from 

 pallescens. 



Measurements. — Type ( c? ad.): Total length, 248; tail vertebrae, 

 76; hind foot, 34. Female topotype: 205, 70, 29. SJcull (of type): 

 Basal length, 40; nasals, 15; zygomatic breadth, 29; mastoid breadth, 

 23; interorbital breadth, 6.7; alveolar length of upper molar series, 8. 



Remarlcs. — This is evidently a rather local form of the hottse group 

 occupying the hot, arid, alkaline desert valley known as Carrizo 

 Plain. It is paler and more strongly differentiated than is the 

 Cuyama Valley form, in which some of the same characters are less 

 emphasized. These specimens it seems better to identify with pas- 

 calis. Dr. Grinnell says of the Carrizo Plain, ^^Faunally and zonally 

 it may be considered very arid, high Lower Sonoran. A sparse 

 prairie vegetation grows on ground that is more or less strongly 

 alkaline over most of the area." ^ 



Specimens examined. — Total number, 9, as follows: 



California (Carrizo Plain): Painted Rock (5 miles north), 3; Simmler (7 miles 

 south), 6. 



THOMOMYS BOTT^ NIGRICANS Rhoads. 

 Stephens Pocket Gopher. 



(PI. V, fig. 16.) 



Thomomys fulvus nigricans Rhoads, Proc. Acad. Nat. Sci. Pliiladelpliia, 1895, 36, 

 Apr. 12, 1895. 



Thomomys aphrastus Elliot, Field Columb. Miis., zool. ser.. Ill, 219, June, 1903. 

 Type from Santo Tomas, Lower California, 18 miles south of Ensenada at 50-100 

 feet altitude. Type collected by E. Heller; type specimen in Field Mus. 

 Nat. Hist. 



Type. — Collected at Witch Creek, 2,753 feet altitude (7 miles west of 

 Julian), San Diego County, California, by F. Stephens, December 22, 

 1893. Type specimen in Acad. Nat. Sci. Philadelphia. 



Distribution. —SouthwesteriL Cahfornia and northern Lower Cali- 

 fornia, from the San Jacinto Mountains, Cal., south to Ubar, Lower 

 California (fig. 7). 



1 Univ. of Cal., Publ. Zool., XH, 314, 1914. 



