438 MAMMALIAN ANATOMY 



upper canine, and its internal cingular swelling is less marked. The 

 fang is shorter. 



The premolars (Figs. 366, 367) differ from the canines by the 

 elevation of the internal basal cingulum into a distinct cusp, or deu- 

 terocone ; the crowns therefore are bicuspid. The outer cusp is con- 

 nected with the inner cusp in front and behind by transverse ridges, 

 and separated by an antero-posterior depression which is divided into 

 two pits by the median ridges of the two cusps. The crown is some- 

 what shorter than the crowns of the canine and of the incisors ; the 

 inner and outer surfaces are equally convex. The fang is usually 

 single; sometimes it is double in the second or the first upper premolar. 



The upper premolars are compressed from before backward and are 

 transversely wider ; the cusps are of nearly equal size. The crowns of 

 the lower premolars are almost circular on cross section, and the inner 

 cusp of the first is generally much smaller than the outer cusp. 



The molars (Figs. 366, 367, 368) are the large teeth with cuboidal 

 crowns and one, two, or three fangs. They usually decrease in size 



FIG. 368. 



2 



TRITURATING SURFACE OF MOLAR TEETH. 



1, first upper molar, right side; 2, view of another specimen; 3, second upper molar, right side; 4, first lower 

 molar, right side ; 5, view of another specimen ; 6, second lower molar, right side. 



from before backward, but are variable in size, especially the last or 

 wisdom tooth, which is frequently rudimentary or even absent. 



The lower molars, combined, strike against all the upper molars 

 and half of the second upper premolar. 



In the lower molars the crown has a greater antero-posterior 

 diameter and presents on its triturating surface five cusps, two on the 

 outer side, two on the inner side, and one behind, formed by the bifur- 

 cation of the antero-posterior valley. The last lower molar usually 



