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 Natalidae are 
evidently the more aberrant, but this is offset by the excessively ab- 
normal thumb of the Furipteridae. The Natalidae show the more 
primitive condition of the teeth. 
Principal subdivisions. — Two genera of Furipteridse are now 
known. 
KEY TO THE GENERA OF FURIPTERIDSE . 
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. 18$. 
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 Amorphocliilus, p. 190. 
Genus FURIPTERUS Bonaparte. 
1828. Furia 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 
Plecotus auritus. 
1866. Furiella Gray, Ann. and Mag. Nat. Hist., 3d ser., XVII, p. 91, Feb- 
ruary, 1866. 
1878. Furia Dobson, Catal. Chiropt. Brit. Mus., p. 356. 
1891. Furipterus Flower and Lydekker, Mammals, Living and Extinct, p. 
666 . 
. Type-species . — Furia, barrens 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 . -- 3 4 5 6 7 . 2-2 
1 2 3 . 1 . - 234567 ^ 3 - 3 ’ ^ 
1-1 
1 - 1 ’ 
pm 
2-2 
3 - 3 ’ 
m 
3 - 
3 - 
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 
