VESPERTILIO. 49 



turning outwardlj ; long, sub-acuminate slightlj diverging 

 tragus ; thumb slender ; foot of moderate size ; ample interfemoral 

 membrane ; last joint of tail exserted. The membranes are of a 

 lightr brown color, tending in some to a darker hue. Hair long 

 and soft, plumbeous at base behind, with light brown tips in- 

 clined to yellowish toward the head. 



The fur in front is dark maroon, or black at base with 

 whitish tips. The basal third of the car is covered with hair at 

 base : at the base of the interfemoral membrane behind a tuft of 

 hair is seen. 



In two specimens the fur had a darker tinge, the tips behind 

 being dark olive-brown, the base being black. 



This species has the largest ear of any of the American species 

 of Vespertilio. 



The cranium is greatly inflated ; the face slender and pointed. 



Dentition. 



fi 1 4 1 fi 



Molars _. Canines — . Incisors — . Canines — . Molars = 38 teeth, 



6 16 16 



Upper Jaiv. — The incisors are grouped in pairs near the 

 canines, separated by an open space. The centrals are markedly 

 bifid, the laterals obscurely so. Of the premolars the first two are 

 very small, the second being the smaller ; the third is larger, com- 

 pressed and bicuspid, the outer cusp much the larger, and longer 

 than any point of the molars proper. The remaining molars not 

 peculiar. 



Lower Jaw. — Incisors trifid, the one adjacent to the canine on 

 either side obscurely quadi-ilobed. Canines with a small basal 

 cusp behind. The premolars small, the two anterior most so, the 

 third is slender ; basal ridge thick. 



Xo specimens have been received from localities east of the 

 Rocky Mountains. It appears to be comparatively common 

 alono- the Pacific coast from Puget Sound to Lower California. 



