212 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



outer upper incisor, make it seem possible that the animal is gener- 

 ically distinct from tickelli and blanfordi. The peculiarities of the 

 prepuce and the presence of a large bone in the penis may indicate, 

 as supposed by Dobson, that the three species form a single group, but 

 the value of these characters is not yet well understood. 



Genus TYLONYCTERIS Peters. 



1872. Tylonycteris Peters, Monatsber. k. preuss. Akad. Wissensch., Berlin, 



p. 703. 

 1878. Vesperus Dobson, Catal. Chiropt. Brit. Mus., p. 184 (subgenus Yes- 



perugo) part. 

 1898. Tylonycteris Miller, Proc. Acad. Nat. Sci. Philadelphia, p. 321, July 



25, 1898 (genus). 



Type-species. — Vespertilio pachypus Temminck. 

 Geographic distribution. — Malay region from Tenasserim to the 

 -Philippine Islands. 



Number of forms. — Only one species is now recognized. 



Characters. — Externally like a small Ep- 

 tesicvs with the entire head greatly broadened 

 and flattened and a conspicuous fleshy pad 

 on ball of thumb and sole of foot. Skull (fig. 

 34) so broad that depth of brain case through 

 audital bulla is barely one-half mastoid 

 breadth; upper surface flat, sloping gradu- 

 ally forward to nares ; rostrum very short and 

 broad, its length scarcely equal to lachrymal 

 Pie. 34— tylonycteris pachy- breadth, its depth at front edge of orbit less 

 pus. adult male, tkong, t h an h a ] f breadth at same region; maxillaries 



LowekSiam. No. 83626. xl'. f ' . 



not concealing tooth rows when viewed from 

 above; a distinct blunt projection over anterior upper edge of orbit, 

 perhaps representing an incipient postorbital process. Dental form- 

 ula as in Eptesicus, and teeth not peculiar except in the following 

 characters : Inner upper incisor conspicuously, bicuspidate, its crown 

 much longer than broad and nearly as long as high, the outer cusp 

 projecting noticeably inward, so that the greatest width of the tooth 

 is at level of its point ; upper canine with a well-developed secondary 

 cusp on posterior cutting edge, unconnected with cingulum and ex- 

 tending nearly to middle of main shaft. 



Species examined. — Tylonycteris pachypus (Temminck). 



Remarks. — This genus is well characterized by the remarkable flat- 

 tening of the skull, a character which it shares with Mimetillus only, 

 combined with the perfectly normal wing. The skull is so unusual in 

 form that it appears almost as if artificially crushed. This tendency 

 to widening is reproduced in the inner upper incisor, but not to any 

 appreciable degree in the other teeth. 



