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. Interpterygoid 

 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. Dirrmus Miixek, Proc. Biol. Soc. Washington, XIX, p. 84, June 4, 1904. 



Type-npecies. — Desmodus youncfi 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 



