1 



A MONOGRAPH OF THE BATS OF NORTH AMERICA. 109 



absent; tlie anterior V nearly of the same size as the second; the heel is 

 rudiniental, the apex is seen as on the posterior jjart of the cusp of the 

 heel in fig". In the third molar the posterior commissure of the protocone 

 is entire and adjuts against the palatal end of the anterior limb of the 

 second V, the second limb being absent. 



Mandibular iveth. — The first incisor presents a trifid cutting edge and 

 is more inclined than the others from within outward, thus permitting 

 much of the base to be seen when the tooth is viewed from above. The 

 second and third teeth gradually increase in thickness, the last named 

 having a distinct nodosity back of, but on the same level with, the trifid 

 cutting edge. Tlie canine is concave on its posterior border, and pre- 

 sents an unusually broad cingulum. Of the three premolars the first 

 is slightly larger than the second, the third is largest of the series, and 

 is trihedral. All are surrounded by complete cingula. The molars are 

 quite as in Vespertilio distinguished by possessing high acute tips.* A 

 minute cusp out lines the posterior border of each molar at the lingual 

 base of the heel. In the first and second tooth the heel is larger than 

 the V, and projects farther on the buccal side and is without a trace of 

 a commissure. The third molar differs from the same tooth in any of the 

 genera of the group in the triangular form of the heel, but is a little 

 smaller than the corresponding part in the first and second molar. It 

 also is without a commissure. 



Notes on the sl-eleton. — Coracoid process of scapula, with base broader 

 than the apex, which is obscurely bifid. The inferior border of tlie 

 innominate bone at the ischium and pubis produced. The thyroid fora- 

 men is subrotund. Eibs, eleven in number. Ulna as in A. fuscus. 

 Palatal ruga?, seven. 



Bemarlcs on sex. — No secondary sexual characters have been detected. 

 Females are much more numerous than males in the Adirondacks. 

 (Merriam, 1. c.) Out of eighty-five caught in one locality, but one was a 

 male. In collections the males are less commonly seen than the females. 

 I have examined ten males and fifteen females. The penis is whitish, 

 long, subcylindroid — prepuce not expanded. 



Habitat. — I)istributed throughout the United States. It would ap- 

 pear from specimens in museums to be much less common toward tlie 

 Western range than in the East. At the date of the publication of the 

 monograydi it had not been found in the Rocky Mountains or in 

 California. According to J. B. Tyrrell (^lam. of Canada, 1888), L. 

 noctivagans is found as far north as Hudson Bay. 



Habits. — 0. Hart Merriam (/. c.) has given close attention to the 

 habits of the silvery bat. In his work on the Mammals of tlie Adiron- 

 dack Region, this writer states that L. noctivagans is the most common 

 bat in that section. In one locality, out of seventy species secured 

 sixty-three were of this species. It is the earliest sj^ecies to appear, 

 and is especially fond of water ways and the borders of hard- wood 



'These are often worn oft'iu the fuHt ami second molars in old iudividnals. 



