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 
Mimetillus , 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 Ilesperoptenus , but distinctly 
expanded distally. Ear 
short. 
Species examined . — Phi- 
let or rohui Thomas. 
Remark s . — This very 
distinct genus appears to 
be related to Tylonycteris , 
though lacking the pecu- 
liar flatness of the skull. 
Genus HISTIOTUS 
Gervais. 
1855. Histiotus Gervais, 
Expect du Comte de 
Castelnau, Zoot, 
Mamm., p. 77. 
1878. Yesperus Dobson, 
Catat Chiropt. Brit. 
Mus., p. 184 (subgenus 
of V esperugo) part. 
1900. Histiotus Thomas, 
Ann. Mus. Civ. di Stor. 
Nat., 2d ser., XX, p. 
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- 
sicus , 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 bullae, 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 macrotus (Poeppig), H. velatus 
(Geoffroy), and IT. montanus (Philippi). 
.Fig. 35. — Philetor rohui. Albert, New Guinea. No. 
123438. x2f. 
