HETEROMYID^ 169 



some extent. Their harxest is irrej^ular and short, and the main 

 dependance must l)e on stored seeds the greater part of the year. 

 Much loss through starvation must occur after unfavorable sea- 

 sons. The breeding season is spring, April to June. The usual 

 number young is four and five, but I have taken several females 

 containing seven foetuses. In favorable seasons two litters of 

 young appear to be raised. 



Perognathus Stephens! ATkrriam. 



STEPHENS POCKET-MOUSE. 



Similar to peniciUatus but very much smaller; skull short; 

 rostrum broader. 



Type locality, the northwestern arm of Death Valley, Cali- 

 fornia. 



Known only from two examples which I caught in that part 

 of Death Valley, known locally as Mesquit Valley. It is prob- 

 ably a dwarf subspecies of pejiicillafiis. 



Perognathus fallax Mkrriam. (Deceptive.) 



SHORT-EARED POCKET-MOUSE. 



Above brownish buff mixed with black ; lateral line buff, us- 

 ually well defined; white spot at base of ear small and faint; an 

 indistinct dusky crescent at base of whiskers; feet and lower 

 parts buffy white; tail pencillate and terminal third crested, up- 

 per side brownish becoming dusky terminally, white below ; skull 

 well arched; mastoids of moderate size; rostrum rather slender; 

 interparietal large, wide; outer sides of nasals parallel to ends 

 posteriorly; ears small, round; pelage coarse and mixed with 

 long coarse spines on the rump and hips, those of the rump 

 black and on the hips white. 



Length about 185 mm. (7.30 inches); tail vertebrae no 

 (4.33); hind foot 25 (i); ear from crown 7.5 (.30). 



Type locality, Reche Canon, San Bernardino Valley, Cali- 

 fornia. 



