214 



BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



times its length along outer edge of alveolus. Skull (fig. 35) with 

 rostrum relatively even more shortened than in Tylonycteris, and 

 with very conspicuous peg-like projections over anterior edge of orbit, 

 but without any of the flattening characteristic of Tylonycteris and 

 Jfimetillus, the depth of braincase through audital bulla nearly 

 equal to width above posterior roots of zygomata. The general out- 

 line of the skull is therefore not unlike that of Lasiurus. Externally 

 about as in Pterygistes, the fifth finger nearly as much shortened, its 

 length equal to metacarpal and half of first phalanx of fourth. 

 Penis with bone well developed as in H es peroptenus, but distinctly 



expanded distally. Ear 

 short. 



Species examined. — Phi- 

 letor rohui Thomas. 



R emarks . — This very 

 distinct genus appears to 

 be related to Tylonycteris, 

 though lacking the pecu- 

 liar flatness of the skull. 



Genus HISTIOTUS 

 Gervaisr 



1855. Histiotus Gervais, 

 Exped. du Comte de 

 Castelnau, Zool., 

 Mamm., p. 77. 



1878. Vvttpents Dobson, 

 Catal. Chiropt. Brit. 

 Mus., p. 184 (subgenus 

 of Vesperugo) part. 



1900. Histiotus Thomas, 

 Ann. Mus. Civ. di Stor. 



Pig. 35— Philetok kohui. Albert, New Guinea. No. Nat., 2d sei\. XX. p. 



1234,38. x2f. 546, July 4, 1900 



(genus). 



Type-species. — Plecotus velatus I. Geoffroy. 



Geographic distribution. — South America. 



Number of forms. — Five species of Histiotus are currently rec- 

 ognized. 



Characters. — Dental formula and structure of teeth as in Epte- 

 sious, but outer upper incisor considerably reduced, its tip scarcely 

 extending beyond cingulum of inner. Skull as in Eptesicus, but 

 more elongated and with larger audital bulla?, their diameter more 

 than double width of space between them. Ears very large, at least 

 as long as head, and united by a ridge or low band of membrane 

 across forehead. 



Species examined. — Histiotus macrotvs (Poeppig), H. relatus 

 (Geoffroy), and H. montunus (Philippi). 



