THE FAMILIES AND GENERA OF BATS. 
151 
Rostrum not specially shortened, at least half as long as braincase. 
Rostrum deep, parallel sided, almost cuboid in form -Pygoderma, p. 166. 
Rostrum not cuboid. 
Nasal region occupied by a narrow emargination extending back 
from nares to between orbits Chiroderma, p. 157. 
Nasal region without emargination. 
Interpterygoid space extended forward as a deep palatal emar- 
gination. 
Rostrum strongly depressed between high supraorbital 
ridges ; nares extending half way from front of pre- 
maxillaries to point of juncture of supraorbital 
ridges Stenoderma, p. 165. 
Rostrum rising above level of low supraorbital ridges ; 
nares extending much less than half way from front of 
premaxillaries to point of juncture of supraorbital ridges. 
Borders of palatal emargination strongly converging 
anteriorly ; inner upper incisor with crown slender, 
noticably higher than long Phyllops, p. 164. 
Borders of palatal emargination not strongly converg- 
ing anteriorly ; inner upper incisor with crown short 
and thick, scarcely or not higher than long. 
Upper molars 3-3 . Ardops, p. 162. 
Upper molars 2-2 l Ariteus, p. 165. 
Interpterygoid space not extended forward as a deep palatal 
emargination. 
Inner upper incisor slightly higher than outer, but not 
twice as large, the two teeth usually not conspicuously 
different in form or size. 
Length of rostrum fully f that of brain case, depth of 
rostrum at front of second premolar more than \ 
that of brain case Uroderma, p. 154. 
Length of rostrum slightly more than \ that of brain 
case ; depth of rostrum at front of second premolar 
less than \ that of brain case. 
Inner upper incisor bifid, m 3 and m 3 present or 
absent, so reduced in size that their presence or 
absence does not affect the form of the sur- 
rounding bone Artibeus, p. 160. 
Inner upper incisor entire, m 3 and m 3 well de- 
veloped, effecting the form of the surrounding 
bone .1 Enchisthenes, p. 162. 
Inner upper incisor much higher than outer, usually, at 
least, twice as large, the two teeth conspicuously dif- 
ferent in form and size. 
First lower molar with distinct postero-internal cusp, 
the crown very different in form from that of the 
last premolar. 
Crowns of molars both above and below heavily 
wrinkled; second upper molar with large pro- 
toconule ; upper canine with large secondary 
cusp Brachyphylla, p. 152. 
