30 
BULLETIN 57 , UNITED STATES NATIONAL MUSEUM. 
incisors with crown well differentiated from root, its length greater 
than height or width, 0 its cutting edge approximately horizontal, but 
with two evident notches. No striking differences in size or form 
between the teeth composing a series, except that the outer lower 
incisor is often wider than the others and with one or two blunt sup- 
plemental cusps posteriorly. 
Canines simple, the upper larger than the lower and usually the 
highest tooth in the entire series. Cingulum well developed, that of 
the lower tooth conspicuously oblique. Shaft subterete, that of the 
upper tooth flattened or slightly concave on inner side, that of lower 
tooth similarly flattened or concave posteriorly. The shaft of the 
upper tooth at base occupies almost entire crown, while that of lower 
appears to. be situated a little in front of middle of crown so that the 
posterior portion 
forms a slight heel. 
Premolars except 
pm 4 essentially like 
the canines, though 
very much smaller 
and with height of 
crown not conspicu- 
ously greater than 
1 e n g t h . Cingulum 
well developed, hori- 
zontal or slightly ob- 
lique. Posterior up- 
per premolar much 
larger than either of 
the others, its cusp 
nearly as high as that of canine, from which it differs in shape in 
the presence of a conspicuous flange-like posteroexternal extension, 
with well-developed cutting edge and supported by a second root. 
Inner side of this extension flat, continuous, with flattened postero- 
internal surface of cusp ; crown with a slight but evident postero- 
internal heel ; cingulum well developed, often forming an anterior 
cusp at base of main cusp and occasionally another on heel. 
The first and second upper molars resemble each other, though 
the second is usually the larger of the two. The crown (fig. 4) is 
much wider than long or high, three-rooted, and set obliquely, so 
that the outer portion is higher than the inner. & Its outer border is 
« Length=diameter in axis of tooth row ; width— diameter perpendicular to 
tooth row ; height=distance from lower edge of cingulum to extremity of high- 
est cusp. 
& Strictly speaking, it is lower, more ventral, but in the position in which the 
teeth are always examined it is higher. 
C 
Fig. 4.— Typical molar teeth of an insectivorous bat. A — 
Crown view of maxillary molar. A.— Crown view of 
MANDIBULAR MOLAR. C. — SIDE VIEW OF MAXILLARY MOLAR. 
ecd. — ENTOCONID. mtS. — METASTYLE. 
hC.— HYPOCONE. pc— PARACONE. 
hcd. — HYPOCONID. pcd. — PARACONID. 
me— METACONE. prC.— PROTOCONE. 
mcd. — METACONID. pred. — PROTOCONID. 
ms— MESOSTYLE. pS. — PARASTYLE. 
