222 M. R. TJiorpe — John Day Pr ornery cochoeri, 



but during the year Leidy's '^Contributions to the Extinct 

 Vertebrate Fauna of the Western Territories" was 

 issued, which contained a lateral view of the skull, and 

 tooth, jaw, and skull parts. In this reference Leidy notes 

 that ''in most of the specimens the temporal surface 

 slopes from the sagittal crest with a slight sigmoid 

 curve"; the course of the squamous suture is followed 

 by a pair of grooves, one in front and the other behind, 

 the former being the more prominent. The bullae are 

 ovoidal, with the antero-posterior diameter the greater, 

 and they extend from the paramastoid process to the 

 middle line of the glenoid articular surface, and project 

 below it for half their length.. 



Marsh placed this species under the genus Eporeodon, 

 which he established in 1875. He based this classification 

 on the presence of large bullae and on the large size of the 

 animal. The name was again changed in 1879 by Cope, 

 who placed it under Eiicrotaphus, without stating his 

 reasons therefor, while in 1884 he placed it under the 

 genus Merycockwnis Leidy. In his key to the species, 

 he laid emphasis on the position of the infra-orbital 

 foramen ; expansion of the posterior part of the zygoma ; 

 moderate posterior production of the palate ; head elon- 

 gated; and otic bullae large and compressed. Douglass 

 was the first to propose a division of the forms of Mery- 

 cochoerus. He referred M. leidyi, chelydra, macrostegus, 

 and montaniis to the new genus Pr ornery cochoerus , which 

 he proposed, with P. superhus (Leidy) as the type ; while 

 he left M. proprius, rusticiis, laticeps, compyessidens, 

 altiramus, and madisoniiis under Merycochoerus. Mat- 

 thew had also definitely determined that many forms, 

 not similar to the type of Merycoclia'rus, had been placed 

 in that genus. He proposed to refer some of the species 

 to a new genus, Paracotylops, with P. superhus (Leidy) 

 as the type. 



Additional characters. — From the many specimens 

 in the Marsh Collection, it is possible to expand the knowl- 

 edge .of this species. The superior molars are internally 

 surrounded by a well developed cingulum. The metastyle 

 is large and robust. It forms an abrupt angle with the 

 hypocone and is situated almost in an antero-posterior 

 line with the paracone. The premolars are normally 

 spaced, as are the incisors. The incisive foramina are 

 roughly right-triangular, with the apex posteriorly di- 



