188 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



more specialized characters of this group are so nearly balanced that 

 it is difficult to form an opinion as to the relative position of the 

 two families. In the structure of the sternum the Natalidse are 

 evidently the more aberrant, but this is offset by the excessively ab- 

 normal thumb of the Furipteridae. The Natalidse show the more 

 primitive condition of the teeth. 



Principal subdivisions. — Two genera of Furipteridse are now 

 known. 



KEY TO THE GENEEA OF FURIPTERIMS. 



Height of braincase, including audital bullae, much less than distance from 

 frontal angle to most posterior point of occipital region ; muzzle and 

 lips nearly simple Furipterus, p. 188. 



Height of braincase, including audital bullae, equal to distance from frontal 

 angle to most posterior point of occipital region ; muzzle and lips with 

 conspicuous warty outgrowths Amorphochilus, p. 190. 



Genus FURIPTERUS Bonaparte. 



1828. Frtria F. Cuvier, Mem. du Mus. d'Hist. Nat., Paris, XVI, p. 150. 

 Not of Linnaeus, 1758. 



1837. Furipterus Bonaparte, Iconogr. Fauna Ital., I, fasc. XXI, under 

 Plecotits auritus. 



I860. Furiella Gray, Ann. and Mag. Nat. Hist, 3d ser., XVII, p. 91, Feb- 

 ruary, I860. 



1878. Furia Dobson, Catal. Chiropt. Brit. Mus., p. 356. 



1891. Furipterus Flower and Lydekker, Mammals, Living and Extinct, p. 

 666. 



Type-species. — Furia horrens F. Cuvier. 

 Geographic distribution,. — Tropical South America. 

 Number of forms. — Only one species of Furipterus is now recog- 

 nized. 



Characters. — Dental formula : 



- 2 3. 1 . --345 67 . 2-2 1-1 2-2 3-3 



12 3. l.-~23 4 5 67*3-3 ,C 1 - l iPm 3^3' m 3^3 =36 - 



Upper incisors subequal, in pairs set obliquely to the sagittal line, 

 the space between outer tooth and canine about equal to diameter of 

 its subterete, slightly antero-posteriorly flattened crown, the median 

 space about twice as great. Each tooth has a sharply conical crown, 

 the height of which about equals greatest diameter, and a well- 

 developed, horizontal cingulum, which rises posteriorly into a small 

 but distinct cusp; height of incisors about equal to that of cingulum 

 of canine. Lower incisors forming a continuous convex row between 

 canines, the outer slightly larger than the inner, their low crowns 

 bluntly trifid on cutting edge, the middle segment larger than either 



