HATCHER : OLIGOCENE CANID^ 77 



The sectorial, or P>, is exceptionally well preserved on the right side in No. 

 553. In form and structure it much resembles the same tooth in Canis urostictus, 

 though it is proportionately a little longer antero-posteriorly than in that spe- 

 cies and is thus a little more specialized perhaps than in that species. I think 

 Professor Scott has somewhat exaggerated the primitive characters of this tooth, 

 for aside from its general resemblance to that tooth in the species just cited I note 

 that the antero-external cone as well as the posterior is quite as trenchant as in 

 certain modern species, Canis cancrivorus for instance ; while the antero-internal 

 cone is proportionately no more prominent than in Canis azarse, C. lagopus, C. vulpes, 

 or certain varieties of C. familiaris. If we compare this tooth with that of Proda- 

 phxnus scottii, a supposed ancestral form known from a single series of teeth discov- 

 ered by the present writer in the Uinta beds of northeastern Utah, the compara- 

 tively specialized nature of this tooth in Daphosnus becomes even more apparent. 

 The antero-external cone of the sectorial in Daphosnus is highly trenchant posteri- 

 orly and pushed inward. The antero-internal cusp is small. The posterior cone is 

 small and trenchant. The shear is oblique, a primitive character, as in Canis can- 

 crivorus and most of the smaller species of modern dogs, not parallel with the 

 longer axis of the skull as in C. occidentalis and the wolves generally. Surrounding 

 the tooth there is a well-defined basal cingulum. 

 In Fig. 4, a, h, c represent the superior sectorials re- 

 spectively of Prodapheenus scottii; Daphosnus felinus 

 (No. 553) and Canis laqopus. The comparative de- ,. . ^ ■ , ■ r.. 



^ ' ^ ^ ^ Fig. 4. Crown view of right superior sec- 



gree of specialization of that tooth in Daph0S7lUS is torials of ; a, Prodapheenus seottU w. & M. at- 



well shown in these figures. ^^^ ^- ^ ^■'' KD<wi'<enus feiinus (No. 553); 



-._-,. •11 n ^ iT^^) Canis lagopus. All natural size. 



M.- IS exceptionally well preserved on both 

 sides in skull No. 553, it is completely surrounded by a basal cingulum which is 

 least distinct on the anterior border. The crown of this tooth is subtriangular in 

 outline and supports three well defined cones of which two are external and one 

 internal. The two external cones are conical in shape, subequal in size and situ- 

 ated well within the basal cingulum. The internal cone is crescentic in form and 

 there is a faint indication of an anterior intermediate cone between it and the 

 antero-external cusp. The molars of the opposite sides converge posteriorly so 

 that the palate is widest between the posterior borders of the sectorials. 



M.- is much smaller than M.-, but has the same general pattern except that the 

 external cones are situated nearer the outer margin of the tooth and the posterior 

 is much smaller than the anterior. 



M.- is represented only by the alveolus, which mdicates that this tooth was 

 small and not functional. 



