VESPERTILIONID^ 269 



Length about loo mm. (3.95 inches) ; tail vertebrae 40 

 ( 1.60) ; ear from crown 15 (.60). 



Type locahty, eastern United States. 



Silvery^haired bats are common in the eastern United States. 

 but appear to be rare west of the Rocky Mountains. I have seen 

 no Cahfornian examples and know of but eight having been 

 taken in the State. In the eastern States this species frequents 

 tlie vicinity of streams and the borders of hardwood forests. 



Geims Pipistrellus Kaup. (A bat.) 

 Size small ; skull small and lightl}- louilt ; ears longer than broad, 

 tapering to a narrow rounded tip ; tragus straight or curved for- 

 ward ; basal fourth of interfemoral membrane thinly haired on 

 the upper side. 



Dental formula, I, 2 — 3; C, i — i ; P, 2 — 2; AT, 3 — 3X2=34. 



Pipistrellus hesperus Ai^lkn. (Western.) 



WESTERN BAT. 



Smallest California species of bat; ear short, barely reaching 

 .lostril when laid forward; ears widely separated; tragus rather 

 short, very blunt and bent forward; feet 

 small ; interfemoral membrane of moderate 

 size, sparsely haired on tlie upper surface 

 near the body, the border not f ring'ed ; face 

 and ears bare, black; color of pelage pale; 

 above ver)^ pale drab ; below brownish white ; 



111 - ' 1 1 1 • 1 1 • 11111. Western Bat. 



all the fur blackish at base; wmgs dull black. 



Length about yi mm. (2.85 inches) ; tail vertebrcX 30 (1.20) ; 

 ear from crown 10 (.40) ; expanse of wings 200 (7.90). 



Type locality, old Fort Yuma, California. 



Western Bats ran.ge from southern and eastern California 

 east to Colorado and Texas. They are a desert loving species and 

 are not common in the coast region of southwestern California. 

 Verv few remain in California in winter. The nc.rthward nu'gra- 



