THE FAMILIES AND GENERA OE BATS. 
135 
greatly reduced, though present. W -pattern even more distorted 
than in Clirotopterus , but still visible. Lower incisors very small, 
about equal in size, forming a concave row between canines and not 
rising to level of cingulum of the large teeth. Their crowns are 
very low, slightly wider than long, with an ill-defined cutting edge 
extending across middle. Lower canines very large, their bases 
nearly in contact postero-internally, the posterior face of shaft and 
outer portion of base flattened and slightly hollowed along region of 
contact with upper canine; cingulum indistinct and without sec- 
ondary cusps. Lower premolars compressed, with rather dull cut- 
ting edges, the middle tooth {pm 3 ) fully in tooth row and about 
half size of anterior premolar, the posterior {pm 4 ) distinctly larger 
than pm 2 , the height of its cusps about equal to length of crown. 
Lower molars still more highly modified than those of Clirotopterus , 
though in the same direction. In all three teeth the protoconid is 
very large, nearly twice as high as the hypoconid ; in m ± the para- 
conid and metaconid are so reduced as to appear as mere appendages 
to the protoconid, the former scarcely breaking the contour of the 
anterior cutting edge of the main cusp, the latter slightly less indis- 
tinct. With the increased height of the tooth both of these rudi- 
mentary cusps have been carried much farther above the base of 
the tooth than the position they normally occupy. The entoconid, 
however, remains in its usual position, though its size is less than in 
Phyllostomus. In m 2 the changes have not progressed so far, the 
paraconid and metaconid retaining their distinctness and normal 
positions with regard to the protoconid, though their size is reduced, 
and they are carried much above the level of the small entoconid. 
The posterior tooth is still less modified, though the same tendency 
is shown, and the entoconid is absent. Skull considerably elongated, 
the breadth of brain case less than one-third greatest length. Sagit- 
tal crest well developed, especially in occipital region. Paroccipi- 
tal expansions distinct, though not very large, strongly concave 
beneath. Rostrum subcylindrical. Zygoma slightly expanded an- 
teriorly and posteriorly. Audital bullae very small, covering less 
than half cochlear surface, their height at inner edge less than 
diameter. Symphysis menti very long, the jaws strongly compressed 
above it. Externally much like Phyllostomus , but with the chin 
smooth as in Chrotopterus , the muzzle much elongated, and the tail 
absent; interfemoral membrane very wide; ear extending to ex- 
tremity of muzzle ; fur normal. 
Species examined.— Vampyrus spectrum (Linnaeus). 
Remarks. — In the peculiar heightening and narrowing of the 
molars this genus shows the most aberrant type of tooth structure 
known in the subfamily. The tooth formula, however, has remained 
somewhat primitive in the presence of a large pm 3 , a character 
probably due to the elongated condition of the mandible. 
