THE FAMILIES AND GENERA OF BATS. 
255 
row between canines; crowns deeply and unequally bifid, the outer 
lobe less than half as large as inner ; height about equal to that of 
large cingulum of canine; no indication of backward prolongation 
of crowns. Canines relatively low and weak, the height of the upper 
teeth distinctly less than the distance between their bases, the diameter 
of the shaft in both maxillary and mandibular teeth much less rela- 
tively to that of crown than in Nyctinomus ; anterior surface with 
longitudinal groove well developed, especially in upper teeth, and 
anterior cutting edge unusually prominent; cingulum well developed, 
forming a distinct posterior cusp above, and anterior and posterior 
cusp below. Anterior upper premolar (pm 3 ) a minute (sometimes 
deciduous) spicule considerably smaller than cingulum of canine. 
Posterior upper premolar (pm 4 ) essentially as in Nyctinomus , but 
main cusp smaller and lower, and postero-internal heel more devel- 
oped; antero-internal cusp well developed but small. Lower pre- 
molars proportioned as in Nyctinomus but resembling the canine in 
the much reduced diameter of the cusp as compared with the crown. 
This is especially noticeable when teeth are viewed from above, the 
periphery of the crowns appearing like an enormously developed cin- 
gulum. Molars essentially normal, but differing from those of Nyc- 
tinomus in several important particulars. In all of the upper teeth 
the protocone is unusually narrow and ridge-like, leaving a very wide 
concave area between bases of cusps ; hyppcone barely indicated by a 
slight angularity of posterior commissure of protocone;- m 3 with 
crown area fully three-fourths that of m 1 and much more than that 
of pm 4 , the metacone and third commissure well developed. Lower 
molars peculiar in the very narrow triangles and strongly incurved 
main cusps. As in the upper teeth, the concavities of the crowns are 
unusually large as compared with the diameter of the cusps. Proto- 
conid of m 2 and m 3 with a distinct incipient secondary cusp on outer 
side slightly above middle. Inner cusps as in Nyctinomus , the ento- 
conid of m 3 equally well developed. Skull broad and much flattened, 
in general appearance not unlike that of Tylonycteris , the dorsal pro- 
file straight from nares to lambda ; depth of braincase about one-third 
greatest breadth, its length about one and one-third times that of ros- 
trum ; depth of rostrum in lachrymal region slightly less than one-half 
lachrymal breadth and about one-half length of rostrum. Lachrymal 
ridges prominent, giving the rostrum a peculiar diamond-shaped out- 
line. Antorbital foramen large, opening conspicuously forward. Palate 
broad, slightly arched, both laterally and longitudinally, the anterior 
emargination about twice as long as wide, extending back to middle 
of canine. Basisphenoid pits barely indicated. Pterygoids parallel. 
Audital bullae about as in Nyctinomus , but slightly more emarginate 
on inner side. Zygoma weak, not expanded at middle. Mandible 
with coronoid process slender, high, and strongly curved backward, 
