THE FAMILIES AND GENERA OF BATS. 97 



it with the Chilonycterime (' Mormopini ') as a section of the Phyl- 

 lostomidre. 



Remarks. — That this group should be regarded as a distinct family 

 is sufficiently indicated by the peculiarities of the wing, shoulder 

 joint, skull, and pelvis. Its relationships, however, are less clear. 

 The large trochin and small trochiter with its slight articulation with 

 the scapula indicate a low position near the Rhinopomidse and Em- 

 ballonuridse, while the structure of the premaxillaries, though 

 obscured by the early fusion of the elements of the rostrum, is not 

 very different from that found in Rhinopoma. It seems probable, 

 therefore, that the three families originated somewhat closely together 

 among the more primitive of the Microchiroptera, though each 

 throughout its subsequent development has followed a different path. 



Principal subdivisions. — Two genera may be distinguished among 

 the species of Noctilionidse. 



KEY TO THE GENERA 01' NOCTILIONID.B. 



Length of tibia unci foot together more than half ' total length : ' upper 

 molars separated postero-internally by wide spaces ; commissure of 

 hypoeone in m l and m." obsolete Xoctilio, p. 97. 



Length of tibia and foot together less than half ' total length ; ' upper 

 molars separated postero-internally by narrow spaces; commissure of 

 hypoeone in m ' and m 2 well developed Dirias, p. 99. 



Genus NOCTILIO Linnseus. 



1776. Xoctilio Linnaeus, Syst. Nat., I, 12th ed., p. 88. 



1808. Noctileo Tiedemann, Zoologie, I, p. 530 (Naehtlowe, V[espertilio] lep- 



orinus Linnams). 

 1821. Celteno Leach, Trans. Linn. Soc. London, XIII, p. 69 (~brooksiana= 



leporinas). 

 1878. Xoctilio Dobson, Catal. Chiropt. Brit, ilus., p. 393 (part). 



Type-species. — Vespertilio leporinns Linnseus. 



Geographic distribution. — Tropical America north to Cuba and 

 southern Mexico. 



Number of forms. — Two forms, leporinus and mastivus, the status 

 of which is not clearly understood, are now usually recognized. 



Characters. — Dental formula : 



-2 3.1. 4567-2-2 1-1 1-1 3-3 



1— .1.-2-4587 l 1^1' ° —1> Pm 2^2' m 3^3= 2 *- 



Upper incisors very unequal, closely crowded at middle of space 

 between canines ; the inner about twice as high as long, .subterete, but 

 with noticeable posterior heel, their shafts curving outward distally, 

 25733— No. 57—07 m 7 



