THE FAMILIES AND GENERA OF BATS. 151 



Rostrum not specially shortened, at least half as long as braincase. 



Kostruni deep, parallel sided, almost cuboid in iovm^Pygoderma, p. 166. 

 Rostrum not cuboid. 



Nasal region occupied by a narrow emarginatiou 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 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 i 



that of brain case Uroderma, p. 154. 



Length of rostrum slightly more than i that of brain 

 case ; depth of rostrum at front of second premolar 

 less than i that of brain case. 

 Inner upper incisor bifid, m " and m „ 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 " and m 3 well de- 

 veloped, effecting the form of the surrounding 



bone EncMsthenes, 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. 



