178 BULLETIN 57 , UNITED STATES NATIONAL MUSEUM. 
Canines large, long, and narrow, with acute points and very sharp 
posterior cutting edge, the upper decidedly larger and more lancet- 
shaped than the lower. Upper cheek teeth minute, scarcely larger 
than lower incisors, the length of the two together scarcely 
equal to length of canine along alveolus. Viewed from the 
side they are subquadrate in outline, slightly higher than long, 
the cutting edge sloping a little backward. Viewed from above 
they are seen to be narrowly wedge-shaped and drawn down to a 
very acute, knife-like cutting edge. Second lower cheek. tooth much 
like the two upper, but with cutting edge sloping forward instead of 
backward. Anterior tooth nearly one-half longer than posterior, its 
cutting edge very oblique, beginning anteriorly at level of alveolus 
and reaching height of next tooth at extreme posterior edge only. 
Posterior cheek tooth nearly as long as anterior, but with the cutting 
edge horizontal except for three or sometimes four irregular serra- 
tions (Plates IX and X, fig. 3). Skull with braincase large, very 
wide posteriorly, narrowing rapidly in front, the rostrum reduced to 
a mere support for the enormous incisors and canines. Palate deeply 
concave laterally, slightly concave longitudinally. Inter pterygoid 
space distinctly wider posteriorly than anteriorly. Audital bullae 
well developed, covering more than half surface of cochleae. Lower 
jaw with posterior segment nearly as long as anterior, its upper and 
lower borders nearly parallel, its anterior border rising abruptly; 
angular process small, nearly in line with alveoli. Ears rather 
small, separate, distinctly pointed. Thumb about one-fifth as long as 
third digit, its metacarpal with a short rounded pad at base and a 
more elongate pad under outer half. Calcar reduced to a wart-like 
exerescence not connected with interfemoral membrane, the middle of 
which terminates about half way between knee and ankle. Tail 
absent. 
Species examined. — Desmodus rotundus (Geoffroy). 
Remarks. — This is the best known and most characteristic genus 
of the family. Except for the simple lower incisors it is the most 
specialized member of the group. It seems highly doubtful whether 
the animals would be able to take other food than blood. 
Genus DI^MUS Miller. 
1906. Diwmus Miller, Proc. Biol. Soc. Washington, XIX, p. 84, June 4, 1904. 
Type-species. — Desmodus youngi Jentink. 
Geographic distribution.- — Brazil and Dutch Guiana. 
Number of forms . — Only the type species is now known. 
Characters. — Similar to Desmodus , but thumb much less elongated, 
only about one-eighth as long as third digit, the two pads on under 
side of its relatively short metacarpal coalesced ; skull with posterior 
segment of mandible higher; teeth as in Desmodus , except that the 
