50 BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
distinct terete cusp slightly in front of middle of crushing surface 
(Plate VIII, fig. 3). 
Species examined. — Niadius princeps (Miller). 
Remarks. — In the somewhat increased size and the squarish out- 
line of the cheek teeth this genus shows a slight approach to Thoop- 
terus ; but the terete cusp in pm 4 and m 4 differs conspicuously from 
the ridge which occupies the same position in the related group. 
Genus THOOPTERUS Matsehie. 
1878. Cynopterus Dobson, Catal. Ckiropt. Brit. Mus., p. 80 (part, latidens= 
nigrescens ) . 
1899. Thoopterus Matschie, Flederm. des Berliner Mus. fiir Naturk., p. 77 
(part). Subgenus of Cynopterus to contain nigrescens , melanocephalus, 
and Manfordi. 
Type-species. — Cynopterus nigrescens Gray (C. latidens Dobson). 
Geographic distribution . — Borneo, Celebes, Morotai, and Luzon. 
Number of forms. — Only two species of Thoopterus are known, T . 
nigrescens (Gray) and T . spadiceus Thomas. 
Characters . — Like Cynopterus in external characters (tail and cal- 
car present). Skull as in Cynopterus , except that interorbital region 
is narrower and zygomata stand out more widely. Teeth as in Cy- 
nopterus ^ but incisors smaller (though of the same proportions) ; 
upper canine without trace of secondary cusp, except a slight angular 
elevation of the cingulum postero-internally ; lower canine with a 
rather abrupt lobule on inner side, developed from cingulum and not 
forming a distinct cusp ; and cheek teeth ( except the small pm 2 
and pm 2 ) greatly enlarged, their crowns subquadrate in outline. 
The crown of pm 4 and m 1 is crossed by a distinct ridge, this better 
developed in Thoopterus nigrescens than in T . spadiceus , in which it 
is somewhat obscured by the unusually large inner lobe. In the type 
of T . spadiceus the smaller upper premolar is absent and no trace of 
its alveolus can be detected. 
Species examined. — Thoopterus nigrescens (Gray), T. spadiceus 
* (Thomas). 
Remarks . — This genus is at once recognizable by its general re- 
semblance to Cynopterus (though with the tail somewhat reduced), 
and the enlarged, subquadrate cheek teeth. As here used the limits 
of the group differ from those originally assigned to it by Matschie 
in the exclusion of the species melanocephalus and blanfordi; the 
first of which is a Cynopterus ; while the second I have made the type 
of the genus Sphcerias. 
