62 THE MERYCOIDODONTID/E 



Leidy placed very little, if any, emphasis on the presence of inflated bulls in Eucrotaphus as of 

 generic value, for in 1854A (p. 55), he described a specimen with large bulls under the new name 

 of Oreodon major. Later, in 1869 (p. 106), he established another species with large bulls, term- 

 ing it Oreodon bullatus. This is significant, inasmuch as the specific name was given almost solely 

 because of the large bulls. Neither of these two species was ever referred to Eucrotaphus by 

 Leidy, nor did he publish any comments when Marsh placed these two species in Eporeodon, 

 although Leidy lived sixteen years after Marsh made that transfer. 



Cope (1884B, pp. 517-519) considered Eucrotaphus jacksoni, Oreodon bullatus, and Eporeo- 

 don occidentalis as synonymous and stated that the typical specimen of O. bullatus Leidy agreed 

 so nearly with the original type of Eucrotaphus jacksoni that he could not doubt their pertinence 

 to the same species. In this same reference Cope assumed that Eucrotaphus superseded Eporeodon, 

 as being the one first given with a definition, and included in Leidy's genus both John Day and 

 Great Plains species with inflated bulls. 



Scott (1890B, p. 340) believed that the name Eporeodon should be restricted to the John Day 

 species, because of the loss of the pollex and the different form of the magnum; not because of the 

 presence of large bulls. On page 372 of the same paper he referred to E. jacksoni as Oreodon 

 jacksoni, although in defining the two genera, Oreodon and Eucrotaphus, he said that the former 

 had small bulls and the latter large ("mit gross aufgetriebenen Bulls"). It would seem that 

 Scott did not consider the bulls of E. jacksoni of sufficient size to classify the species as a true 

 Eucrotaphus. 



In the later publications of Loomis, Matthew, Osborn, Scott, and many other vertebrate paleon- 

 tologists the genus Eucrotaphus has been almost completely abandoned in favor of Eporeodon. 



It is my opinion that there is a reasonable doubt as to exactly what genus should include this 

 type specimen of Eucrotaphus. It has a certain resemblance not only to Eporeodon, but to Agrio- 

 chcerus, as well as to two or three other of the upper Oligocene-lower Miocene genera of this 

 family. The type specimen seems to me to be inadequate for a genoholotype, and therefore 

 Eucrotaphus is indeterminate, due to the paucity of characters sufficiently diagnostic to afford a 

 clear-cut generic or even specific definition. 



I realize that this is a matter of personal opinion and that other workers may reverse my 

 decision. At any rate, I believe either that the species now listed under Eporeodon should remain 

 there or that all of them should be transferred to Eucrotaphus, if this genus is considered sufficiently 

 well defined to stand alone. I cannot see any generic distinctions between the Great Plains and the 

 John Day individuals of this group. There are large numbers of these specimens, studied in recent 

 years, which show that the distinctions postulated by Douglass (1906, p. 566) grade one into the 

 other and are not distinctive of either the John Day or the Great Plains areas. 



Measurements may be taken from the illustrations. 



Etymology: Eucrotaphus (well + temple, in allusion to the large size of the squamosal part 

 of the temporal bone). 



Genus EPOREODON Marsh 1875 



Tables 3-4 



Original Reference: Notice of new Tertiary mammals. IV. Amer. Jour. Sci. (3), IX, pp. 249-250. 

 Genotype: Eforeodon occidentalis (Marsh) 1873. 



Genoholotype: Cat. No. 10142 Y.P.M., moderately well-preserved skull, lacking portion of muzzle 

 anterior to P 2 , supraoccipital crest, superior portion of brain case, and median parts of zygomata. 



Distinguishing Characters: Average skull size larger than that of Merycoidodon culbertsonii 

 (170 mm. to 255 mm.); typical skull mesocephalic but in some cases dolichocephalic and brachy- 

 cephalic; nasal bones unreduced; premaxillaries not coossified, transversely wide distally, and 

 changing the long diameter to anteroposterior upwardly just before reaching the nasal bones; 

 muzzle moderately narrow; face, including orbits, more than half of skull length; orbits medium 

 to large and closed; antorbital fossa present with but one exception, confined to lacrimal bone, and 

 normally deep; frontals wide and unreduced; brain case elongate and moderately narrow; supra- 



