of the Genus Stenomylus. 



305 



the pit, the tooth in addition to its great height must increase 

 still more by growth at the base during life. 



The lower dentition. — The lower incisors are flattened and 

 expanded at the top so that each successive incisor slightly 

 overlaps the preceding one. The laterally compressed canine 

 is grouped with the incisors and has assumed the incisiform 

 character completely. Even the iirst premolar is semi-incisi- 

 form and stands close behind the canine, being thus in the 

 incisor group. Behind this there is a considerable gap in front 

 of the second premolar, which, though two-rooted, is con- 

 siderably reduced. Behind this in turn occurs a wide dias- 

 tema followed by the small but sharp third molar. It is only 



Fig. 6. 



Fig. 6. Stenomylus hitchcocki, mandible with lower dentition, x 1 / 2. 



the fourth premolar which is to any degree functional as a 

 grinding tooth, and this is a short, narrow, single-cusped tooth 

 without any pit, of molariform adaptation. The three molars, 

 however, are developed into deep hypsodont and compressed 

 teeth, each with its deep pits. The iirst molar is the smallest 

 of the three, consisting of two lobes, which like the others 

 have a straight face on the inner side, there being no columns 

 except the parastyle on the front margin of each molar. This 

 tooth cuts the gum apparently at about the end of the first year 

 and wears very rapidly, for when the third molar appears this 

 tooth has worn below the base of the pit ; but it is to be remem- 

 bered that in the lower teeth the pits are not nearly as deep as 

 in the upper molars. While the second lower molar is some- 

 what larger, it is otherwise like the first. But the third molar 

 has three lobes, the last one being only a little smaller than the 

 two preceding it. The extreme depth of this tooth is shown by 

 the illustration (fig. 7), which is a typical young specimen of 

 S. hitchcocki, and shows that in a crown 34 mm high the pit is 



