350 University of California Publications in Zoology [Vol. 10 



fine-grained sandy ground away from cultivation, on the desert 

 floor close to the base of the foothills, and up in the mouths 

 of canons. Fresh mounds are rarely distinguishable on the dry 

 desert, and it is difficult to find the open burrows in the loose 

 dry earth of the desert. No unmistakable signs of gophers were 

 noted at all, far out on the desert floor away from the base of 

 the mountains. 



February 9 to 12 was evidently about the beginning of the 

 breeding season. The testes of the males were enormously devel- 

 oped. Three females were taken containing small embryos, four, 

 four, and three, respectively. All the rest of the females had 

 not yet bred, save one, which had a litter of half-grown young, 

 one of which was captured on the 11th. In no case were males 

 and females captured in the same burrow. Each burrow appeared 

 to be occupied by but one individual, save in the case where 

 there were young. Out of the forty-two gophers, fourteen, or 

 just one-third, were males. Two to one is the proportion of 

 females to males in at least one other species of the genus (see 

 Grinnell, 1908, p. 151). The dimensions of the comparable males 

 have been given in another connection (Grinnell, 1912a, p. 176). 



In our 1908 explorations, gopher workings were seen in the 

 Pinon Flat and Deep Canon country, but we failed to secure 

 specimens, and their identity remains conjectural. Thomomys 

 perpallidus, as recently restricted (Grinnell, 1912a, p. 171), 

 is still a well-marked form ; but as far as material at command 

 goes, it is found only in the immediate vicinity of Palm Springs. 



Thomomys cabezonae C. H. Merriam 



Cabezon Gopher 



Twenty-four of the gophers taken are referred by us to this 

 species. Sixteen of these (nos. 12-18-1263) were obtained at 

 the north base of the mountains in San Gorgonio Pass, 1700 feet 

 altitude, and close to Cabezon, the type locality of cabezonae, 

 and are therefore topotypes. Two others are from Snow Creek 

 (nos. 1561-1562) at 1500 feet, six miles to the eastward. Five 

 are from Schain's Ranch, 4900 feet (nos. 1624, 1626, 1638-1640), 



