30 



BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 



m ts 



incisors with crown well differentiated from root, its length greater 

 than height or width, 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 

 P c f\ C forms a slight heel. 



pre Premolars except 



pm * essentially like 

 the canines, though 

 very much smaller 

 and with height of 

 crown not conspicu- 

 ously greater than 



p IG , 4.— Typical molar teeth of an insectivorous bat. A.— length. Cmgulum 

 Crown view of maxillary molak. B.— Crown view of y^-gll develoDed hori- 



TWATjnTWTTT.AR Mm.AP f!: — KtDF. VIEW OF MAXILLARY MOLAR, -y ' 



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 hi shape in 

 the presence of a conspicuous flange-like postero-external 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. 6 Its outer border is 



a Length = diameter in axis of tooth row; width=diarneter perpendicular -to 

 tooth row ; height=distance from lower edge of cingulum to extremity of high- 

 est cusp. 



6 Strictly speaking, it is lower, more ventral, but in the position in which the 

 teeth are always examined it is higher. 



MANDIBULAR MOLAR. C— SIDE VIEW OF MAXILLARY MOLAR. 



ecd. — ENTOCONID. Wis. — METASTYLE. 



kC. — HYPOCONE. pC. — PARACONE. 



ftcd— HYPOCONID. pcd.— PARACONID. 



mc. — METACONE. pre. — PROTOCONE. 



mCd. — METACONID. prCd. — PROTOCONID. 



ms. — MESOSTYLE. pS. — PARASTYLE. 



