CEEODONTA. 283 



heel on the inner side of the posterior base; anterior base injured. The 

 first true molar has very little sectorial character, and resembles the corre- 

 sponding tooth of a Pelycodus. It differs entirely from that of the D. fmida- 

 minis in the possession of a well-marked posterior internal cusp, which is 

 connected by a ridge with the large internal lateral cusp of the heel. The 

 anterior cusps of opposite sides subequal. A weak external basal cingulum 

 on the anterior half of the crown; no internal cingulum. Enamel of the 

 teeth wrinkled. 



Measurements. 



M. 



Length of premolar series 0140 



Elevation of Pm. iv 0040 



Diameters of M.i^''"*^™?"^*^"*"- "^^^^ 



( transverse Wi'i 



Depth of ramus at Pro. i 0090 



Depth of ramus at M i 0113 



On comparison with the D. fundaminis, the first molar tooth has the 

 same dimensions, but the premolars are considerably smaller. The ramus 

 is also shallower. Found by Mr. Baldwin in the Puerco beds of Northwest- 

 ern New Mexico. 



DIDELPHODUS Cope. 



American Naturalist, June, 1882, p. 522. 

 ? 1 ? ^ 9 



Dental formula: I. ^; C. -; Pm. ^; M. -. Second superior molar a 



simple cusp; third with an internal cusp; fourth with a simple external cusp 

 without heel. True molars with two external cusps, set well in from the 

 external border. Last superior molar narrowed and transverse. Inferior 

 dentition like that of Stypoloplius, except that the fourth premolar has a 

 small internal tubercle. Canine large. ' Symphysis not coossified. 



This genus differs from Deltatherium in the presence of an additional 

 premolar tooth in the lower jaw. It is uncertain whether there is a first 

 superior premolar, but I cannot find an alveolus for it. From Stypohplms 

 it differs in the triangular character of the superior molars and the simple 

 trenchant form of the fourth superior premolar. In the latter respect it is 

 identical with Proviverra of Riitimeyer. I should refer the American spe- 



