58 



SINCLAIR— THE SMALL ENTELODONTS 



in No. 1481, Am. Mus., they are as strongly compressed laterally as 

 in our No. 11440 (Fig. 4 B), a typical A. mortoni as noted later. 



Certain unassociated upper molars from the Cypress Hills locality 

 are referred to A. coarctatum by Cope and Lambe.^ Of these, the 

 third molar, as figured by Lambe, has three well-developed and sub- 

 equal cusps in the posterior row and strong external cingulum, quite 

 different from the less complex type of cuspidation found in the 

 specimens just described. Whether this specific reference is correct 



/T /^7°f 



*7'«.3. 



Fig. 3. Archaotherium mortoni. Series of crown views, from contem- 

 porary animals, of the third upper molar, one half the natural size, showing 

 some of the variations in cusp development. A and B are of the left side; 

 the others are of the right side. C is drawn from a tooth not fully erupted, 

 the anterior cingulum being still covered by bone, pr, protocone; pi, proto- 

 conule ; pa, paracone ; mc, metacone ; vil, metaconule ; pr, posterior cingulum ; 

 hy, hypocone. 



can not be determined until lower jaws of unquestioned coarctatufh 

 type are found in association with upper molars. 



The skulls from Hat Creek and Bear Creek differ greatly in size 

 (see table of measurements) and the latter has been deformed some- 

 what by crushing, and has, unfortunately, lost the tip of the cheek 



* L. M. Lambe, " The Vertebrata of the Oligocene of the Cypress Hills, 

 Saskatchewan," Contributions to Canadian Palccontology, Vol. III., Part IV., 

 p. 26, PI. II., Figs. 10, II, 1908. 



