164 CALIFORNIA MAMMALS. 



(usually narrow) on the sides with but little intermixture of 

 black; a small or obscure whitish spot at the base of the ear; a 

 more or less distinct crescentic blackish line at the base of the 

 whiskers; tail buffy, darker above. Young; drab buff above. 



Length about 120 mm. (4.70 inches) ; tail vertebrae 62 

 (3.15) ; hind foot 18 (.70). 



Type locality, San Bernardino, California. 



Interior valleys of southern California. Occasionally com- 

 mon locally after wet seasons, but usually rare. I have never 

 seen them abundant but once, this was after the wet spring of 

 1884, when they became plentiful at San Bernardino for two 

 or three years, almost disappearing later. 



The young are usually four in number, and are lx)rn in 

 May, June and July. One female in the gray immature pelage 

 taken June 4th, contained but two foetuses. It is my impression 

 that this species does not often dig burrows, but hides under 

 weeds and dead leaves. 



Perognathus pacificus Mearns. (Of the Pacific.) 



SAN DIEGO POCKET-MOUSE. 



Very small; above ochraceous buff thickly mixed with black; 

 a narrow lateral stripe of buff which widens on the sides of the 

 head; distinct narrow black crescents at the base of the whiskers; 

 a small white spot at the base of the ear and another indistinct 

 larger buff one behind the ear; feet and lower parts white; tail 

 buff below, darker above ; skull small and narrow ; mastoids less 

 inflated than usual in the small species; transverse breadth of 

 interparietal greater than the longitudinal. 



Length about 109 mm. (4.30 inches) ; tail vertebrae 54 

 (2.12); hind foot 15.5 (.60); ear from crown 5 (.20). 



Type locality, mouth of the Tijuana River, near the last 

 boundary monument. 



This exceedingly small Pocket-Mouse is one of the rarest of 

 mammals yet, though some one may find them plentiful unex- 



