98 
BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
strongly in contact at about middle; the outer placed somewhat 
behind inner, beyond the well-developed cingulum of which they 
scarcely extend, their terete crowns with small inner cusp; lower 
incisors closely crowded between canines, the crown larger than high, 
and. about as broad as long, narrowed posteriorly, the upper surface 
with distinct concavity, and dull cutting edge distinctly, though not 
deeply, bilobed. Upper canines high and short, with distinct, though 
not unusually developed, very oblique cingulum, but no secondary 
cusps, the inner surface slightly concave, with median ridge, the 
outer surface uniformly convex; lower canines not peculiar except 
for a slight twist in the shaft at about middle. Cheek teeth both 
above and below essentially normal, except that the main cusps of the 
upper molars are placed unusually far inward and the mandibular 
molars project very noticeably beyond outer edge of jaw. Upper 
premolar nearly parallel sided, its crown more than twice as broad as 
long, its two cusps well developed and strongly resembling a pro- 
tocone and paracone. Lower premolars showing no special peculiar- 
ities, the posterior (pm 4 ) almost in contact with canine, the anterior 
much crowded inward. First and second upper molars subequal, the 
four cusps, three styles, and the commissures all well developed ; 
hypocone very distinct, terete, but with scarcely a trace of commissure. 
Posterior surface of each tooth strongly concave, so that the three 
molars are separated by very noticeable spaces. Third upper molar 
with about half the crown area of second, its three cones, two styles, 
and three commissures well developed. Lower molars with all the 
normal elements distinct. Form of skull highly characteristic; brain 
case deep, short oval in outline, with very prominently flaring, shelf- 
like mastoid region and distinct sagittal crest. This divides ante- 
riorly into two rather high ridges extending out nearly perpendicu- 
larly and strongly downward over broadly terete interorbital region. 
Rostrum about half as long as braincase, highly arched, the nares 
almost tubular and opening directly forward except for a slight 
posterior emargination. Palate distinctly concave laterally, almost 
flat antero-posteriorly ; behind tooth rows it narrows very gradually, 
much as in the Pteropidae. Audital bullae small, but covering about 
half surface of cochleae. Ears separate, slender and pointed, with 
well-developed tragus. Muzzle pointed, the nostril pad strongly 
projecting, but nostrils not tubular. Lips very full. Chin with well- 
developed cross ridges. Tibia and foot together equaling about 60 
per cent of total length. Tail well developed, considerably more than 
half as long as femur, extending about to middle of interfemoral 
membrane. 
Species examined. — Noctilio leporinus (Linnaeus), including both 
“ leporinus ” and “ mastivusj 5 
