THE FAMILIES AND GENERA OF BATS. 
235 
philus being supposed to have strictly Vespertilionine relationships, 
while Antrozous appeared to be derived from some primitive Phyl- 
lostomine stock. While the genera are very distinct, I am inclined 
to accept Peters’s view and place them together as a subfamily of 
Vespertilionidae. In any event, Nyctophilus seems to be not specially 
allied to the Plecontines, as its muzzle is very differently formed, and 
the teeth show no tendency to become reduced in strength. 
Principal subdivisions. — Two genera of Nyctophilinse are now 
known, one peculiar to each of the regions inhabited by the group. 
KEY TO THE GENERA OF NYCTOPHILINiE. 
Lower incisors 2-2 ; extremity of muzzle with distinct horseshoe-shaped 
ridge Antrozous , p. 235. 
Lower incisors 3-3 ; extremity of muzzle with low but evident nose- 
leaf A yctophilus, p. 236. 
Genus ANTROZOUS H. Allen. 
1862. Antrozous H. Allen, Proc. Acad. Nat. Sci. Philadelphia, p. 247. 
1878. Antrozous Dobson, Catal. Chiropt. Brit. Mus., p. 170. 
1894. Antrozous H. Allen, Monogr. Bats N. Amer. (1893), p. 64, March 14, 
1894. 
1897. Antrozous Miller, North American Fauna, No. 13, p. 42, October 16, 
1897. 
Type-species. — V espertilio pallidus Le Conte. 
Geographic distribution. — Warmer parts of western North Amer- 
ica, from Texas to the Pacific coast, and from the Columbia Piver to 
central Mexico. 
Number of forms. — Three forms of Antrozous are now recognized. 
Characters. — Dental formula : 
- 2 - . - 1 . 4 5 6 7 . 1-1 1-1 
12 -.- 1 . - 2 - 4 5"6 7 4 2 ^ 2 ’ ° \-V pm 
1-1 
2-2 
, m 
3-3 
3-3 
= 28 . 
Upper incisor large, simple, its shaft more than half as high as 
canine, against which the tooth is crowded at base ; lower incisors sub- 
equal, trilobed, the high, narrow crowns very strongly imbricated. 
Canines moderately large, not peculiar in form, the cingulum distinct 
but small. Cheek teeth normal both above and below ; m 1 and m 2 
without hypocone, and with base of protocone so short that it does not 
extend back to level of metacone, the W pattern rather shallow but 
perfectly distinct, m 3 with less than half the crown area of m 1 or m 2 > 
its protocone, para cone, and parastyle well developed, but no other 
cusps present, and the second commissure reduced to the merest trace ; 
lower molars with outer cusps unusually high as compared with those 
of inner side ; m 3 with second triangle much reduced, and apparently 
consisting of the hypoconid only. Skull with rather high, smooth 
braincase, deep interorbital region, and large rostrum, the dorsal 
profile with no special concavities or convexities; rostrum decidedly 
