250 E. L, Troxell — Entelodonts in Marsh Collection. 



fragment of the skull with two premolars. Although the 

 first description was almost as fragmentary as the fossil, 

 we do find some accurate measurements, and later there 

 were published some drawings. Peterson has discovered 

 at the Carnegie Museum some excellent skulls which he 

 identifies as A. mortoni, and has thus put the specific 

 name on a more solid foundation. 



Archceotherium, robustum Leidy. This species was 

 made on rather an important specimen in the collection 

 of Doctor Owen, from the John Day region, and the name 

 may some day be revived by a careful study of the origi- 

 nal material, the location of which is not known at present. 

 Peterson in his memoir makes no mention of this species, 

 which Leidy himself tells us is no doubt the male individ- 

 ual of A. mortoni. 



Archceotherium in gens (Leidy). The drawing pub- 

 lished by Leidy in 1869 is by him "referred" to the spe- 

 cies made in 1856 ; whether that may be interpreted to 

 mean the same actual specimen we can not be sure. 

 Peterson says that the type is not now known, and Leidy 

 himself stated that he was "prepared to admit that these 

 larger fossil remains may have pertained to robust males 

 of Elotherium mortoni/' The type specimen represents 

 "a huge species, indicated by several mutilated canines, 

 the anterior extremity of a lower jaw without teeth, and 

 the crown of an inferior molar tooth. ' ' 



Archceotherium superbum (Leidy) is like the last spe- 

 cies ; of it Peterson says the "type is altogether inade- 

 quate "; furthermore the geological age and present loca- 

 tion also are unknown, and in his estimation the name be- 

 comes a thing simply of historical interest. 



Archceotherium imperator (Leidy) is represented by 

 fragments which are unsuitable as types and Peterson 

 states that they "should therefore be regarded only as an 

 historical record of the first report of the existence of 

 entelodonts in the John Day formation." 



Archceotherium eras sum (Marsh) was founded on two 

 skeletons in the Yale Museum concerning which there is 

 considerable misunderstanding ; it is certain that the com- 

 plete zygomatic arch, iig. 9, with associated skeletal parts 

 (Cat. No. 12020 ) 2 is one of the specimens, of the features 

 of which Professor Marsh says: "The most striking of 



2 Catalogue numbers cited refer to specimens in the Yale Fossil Vertebrate 

 Collection in the Peabody Museum. 



