A MONOGRAPH OF THE BATS OF NORTH AMERICA. 161 



one-sixth. In the former specimen the fourth metacarpal bone is 2'""" 

 longer than the forearm; in the latter it is Just as long'. 



Bcnuirls on sex. — The i)rebrac]iial membrane is smaller in the female 

 than in the male, and stops at the distal fourth of fifth of the forearm. 

 In one example only of nine specimens of females examined was a large 

 antebrachial membrane present. Of three males examined two have 

 large antibrachial membranes which extend free to the thumb, while 

 the third terminates at the distal fifth of the forearm. Tlie auricle is 

 thicker in the fenuile than in the male. The penis is furnished with a 

 cauliform prepuce. 



Habitat. — According to Le Conte, A. cinerea is more common in the 

 Northern than in the Middle or Southern States. Judging from the 

 numbers found in collections, it is a rare bat in the far West. J. B. 

 Tyrrell (I. c.) states that it is found in Canada from Nova Scotia to 

 Manitoba. Eichardson (American Borealis, 1829, ii) obtained it on 

 the Ked Elver in British North America at an altitude of 54°. It is 

 likely that it frequents mountain ranges and table-lands in preference 

 to river valleys or coastwise regions. Mr. Thomas Say reports (Long's 

 Expedition to Eocky Mountains, 1823, i, 1G7) its collection at Council 

 Bluffs, Iowa. Say (I. c.) mentions that Prof. Barton presented a speci- 

 men of this bat to the Philadelphia Museum that had been captured in 

 Philadelphia. 



C. Hart Merriam (Mammals of the Adirondacks Eegion, 1886, 176) 

 notes that tlie flight in this species is swift and irregular. The nightly 

 range is greater than in any member of the fauna. Whenever the tem- 

 perature of the air is above 59° P. it may be seen on the wing. Like 

 many bats, it is active just before evening and at dawn. It has been 

 caught hanging from a twig of a tree as in the case of A. noveboracensis. 

 When kept in confinement it suspends itself by the claws of the feet. 



Measurements taken as an average of four individuals. 



Millimeters. 



Head aud body (from crown of head to base of tail) 68 



Length of arm 37 



Length of forearm 54 



First digit: 



Length of first metacarpal bone 4 



Length of first phalanx 8 



Second digit: 



Length of second metacarpal bone 59 



Length of first phalanx 8 



Third digit : 



Length of third metacarpal bone 60 



Length of first phalanx 19 



Length of second jihalanx 23 



Fonrth digit: 



Length of fourth metacarpal bone 53 



Length of first phalanx 11 



Length of second phalanx 13 



111— No. 43 11 



