132 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



Species examined.— Phylloderma stenops Peters (type specimen of 

 Guandira oayenensis Gray, of which the skull is badly damaged). 



Remarks.— Although showing throughout a general resemblance to 



Phyllostomus this genus is readily distinguishable by the bifid middle 



upper incisors, the narrow lower molars, and the presence of the 



minute pm 3 . 



Genus TRACHOPS Gray. 



1825. Istiophorus Gray, Zool. Journ., II, p. 242, July, 1825 (part). Not of 

 Lacepede, 1802. 



1846. Histiophorus Agassiz, Nomenelator Zool., Index Univ., p. 183. 



1847. Trachops Gray, Proc. Zool. Soc, London, p. 14. 



1865. Trachyops Peters, Monatsber. k. preuss. Akad. Wissensch., Berlin, p. 



512. 

 1878. Trachyops Doeson, Catal. Chiropt. Brit. Mus., p. 481. 



Type-species. — Trachops fuliginosus Gray = Vampyrus cirrhosus 

 Spix. 



Geographic distribution. — Tropical America, north to southern 

 Mexico. 



Number of forms. — The type species is the only form now recog- 

 nized. 



Characters. — Dental formula : 



-2 3. 1. --34567.2-2 1-1 2-2 3-3 „ , 



ra^T-T5T8T667 * 2 = 2' ° 1 = 1 ** 8 = 8' m 3^=^ 



Maxillary teeth like those of Phyllostomus (anterior face of canine 

 similarly grooved) , but outer incisor very small, almost hidden 

 between canine and inner incisor, cheek teeth relatively larger than 

 in Phyllostomus, the greatest transverse diameter of m 2 nearly 

 equal to width of palate a ; m 1 and m - with large, well-defined 

 hypocone and noticeably elongated postero-external segment. Ex- 

 cept for the presence of a minute pm 3 smaller than the lower incisors 

 and crowded completely from toothrow on inner side, so as to be 

 invisible from without, the mandibular teeth differ from those of 

 Phyllostomus in the noticeable compression or narrowing of the 

 • crowns of the molars, and the general elevation of all the cusps 

 except the hypoconid of m t and m .,, which is somewhat more reduced 

 than in the related genus. The entoconid of these two teeth is, how- 

 ever, much more developed than it is in Phyllostomus. Skull more 

 elongated and rounded than that of Phyllostomus; interorbital 

 region smoothly rounded and somewhat depressed; posterior zygo- 

 matic expansion angular-emarginate in front, the anterior expan- 

 sion barely indicated; audital bullce covering about half surface of 

 cochleae, their height fully equal to width. Externally similar to 



a In Phyllostomus lmstatus it is about one-half, in P. discolor considerably 

 less than half, and in P. latifolius and /'. longifolius slightly more than half. 



