E. L. Troxell — Entelodonts in Marsh Collection. 241) 



(Marsh) 1893. P. bathrodon (Marsh) 1893. Dceodon 

 shoshonensis Cope 1878. Ammodon leidyanus (Marsh) 

 1893 (Miocene). Binohyus hollandi Peterson 1905 (Mio- 

 cene ) . 



Let ns note the status of each of these. 



Entelodon magnus Aymard is an interesting specimen 

 of which the skull and lower jaws and other skeletal mate- 

 rial constitute the first fossil of the sort found ; for many 

 years no distinctions between it and the American forms 

 were noted. 



Entelodon coarctatus Cope is undoubtedly quite dis- 

 tinct from any other American species, and from the ob- 

 servations which follow 1 it is apparent that if any of our 

 entelodonts are closely related to E. magnus of France, 

 it is this specimen described so long ago by Professor 

 Cope. 



Entelodon calkinsi (Sinclair), referred by Peterson 

 (1909, pp. 64-65) to the strange genus Dceodon, in this 

 paper is put under the new genus Choerodon. The speci- 

 men was found in the John Day beds of Oregon ; it is dis- 

 cussed more fully in connection with Choerodon caninus, 

 genoholotype, on a later page. 



Archceotherium, mortoni Leidy was the first species 

 found in America. The type specimen consisted of a 



1 These two species are shown to be similar from the subjoined table of 

 ratios: P 2 of E. coarctatus is relatively rather small as indicated by the 

 ratio 66.9 per cent, while both P 3 and P 4 are comparatively large, with 

 the ratios 80 and 80.6 per cent. The relation of P 3 and P. A in each case is 

 identical. 



Other resemblances between the two are: the very small diastemata or 

 their absence between the premolars, the first premolar small and single- 

 rooted, crowns of premolars wrinkled and compressed, with cutting edges 

 fore and aft. The main known differences between the two species are: 

 the relatively larger size in general and of P 2 in particular, and the seem- 

 ingly rougher teeth and well developed cingula of E. magnus. These dif- 

 ferences certainly can not mark a greater variation than that of species, 

 and so we would replace the American form under the old name of 

 Entelodon. 



Katios from measurements taken from the drawings of Cope and 



Peterson. 



Length of molar premolar series. 



Length of three lower molars 



Height of enamel on crown of P x 

 Height of enamel on crown of P 2 

 Height of enamel on crown of P 3 

 Height of enamel on crown of P; 



coarctatus 



Ratio E. magnus 



mm. 



% 



mm. 



167.1 



74.0 



226.0 



71.5 



75.8 



94.4 



15.8 



73.1 



21.6 



18.2 



66.9 



27.2 



25.4 



80.0 



32.0 



20.0 



80.6 



24.8 



