476 SINCLAIR— ENTELODONTS FROM THE 



In preparation the skull and jaws have not been separated from 

 their position in the matrix, so that the triturating surfaces of the 

 teeth have not been exposed. The specimen shows interesting path- 

 ological structures in the shape of battle scars which will be dis- 

 cussed in a subsequent paragraph on the habits of entelodonts. 



ArchcBotherium mortoni Leidy. 



Five skulls of small entelodonts secured by the Princeton 1920 

 Expedition from the " turtle-oreodon layer " of the lower Oreodon 

 beds in the drainage basins of Indian and Bear Creeks in Penning- 

 ton County, South Dakota, agree so closely with Mr. Troxell's 

 A. clavus clavus that, with his description before me, I can not sep- 

 arate our material from his. Another specimen. No. 11009, from 

 the lower Oreodon beds in Corral Draw, collected by Mr. H. F. 

 Wells in 1894, shows remarkably close agreement with A. clavus 

 darbyi Troxell, the few dififerences between them not being of 

 specific rank in my opinion. None of this material, however, have 

 I been able to separate from A. yn-ortoni. Although the type^ of this 

 species is a fragment of the left side of the face, with pj and p^ in 

 place, more complete skulls, originally in the collection of Dr. 

 Owen, were later referred by Dr. Leidy himself to A. mortoni and 

 beautifully figured,'^ constituting " heautotypes " ^ of the first order, 

 of importance. These specimens lack both dependent and posterior 

 jugal processes, but otherwise agree closely with the Princeton ma- 

 terial, allowing a certain amount of variation in size for difference 

 in age, sex and individuals. Whatever be the ultimate status of 

 Mr. Troxell's species, I am disposed to refer all of our small entelo- 

 donts from the Big Badlands to Leidy's A. mortoni. 



Mr. Troxell's figured specimen of A. clavus clavus lacks the tip 

 of the cheek flange, and it is also indicated as missing in the specimen 

 figured by Peterson^ and referred to A. mortoni. As this is com- 

 plete in two of our Princeton skulls, I have illustrated it in the ac- 

 companying figures (Figs. 7, 8). 



" Figured by Dr. Leidy in " Ancient Fauna of Nebraska," PI. IX., Fig. 3. 

 7 "Ancient Fauna of Nebraska," Pis. VIII., IX. 



* Schuchert and Buckman, Science, n. s., Vol. 21, No. 545, p. 900, 1905. 

 ^ " A Revision of the Entelodontidae," Memoirs Carnegie Museum, Vol. 

 IV., No. 3, Figs. 4-6, May, 1909. 



