56 EUCROTAPIIUS. 



EUCROTAPHUS, Leidy. 



Eucrotaplius Jacksoni, Leidy. 



(Plate A'II. Figs. 4-6.) 

 Eucrutaplius Jacksoni, Leidy: Proc. Acad. Nat. Sci., 1850, v. 92. 



Elicrotaphus atiritiis, Leidy. 

 (Plate Vn. Figs. 1-3.) 

 Eucrotaplnis auritus, Leidy: Owen's Rep. of a Geol. Surv. of Wise, etc., 563. 



The genus Eucrotaphus was originally proposed in the Proceedings of the 

 Academy of Natural Sciences of Philadelphia, upon a cranial fragment presented to 

 the Society by Mr. Alexander Culbertsou through his father, Mr. Jose^jh Culbertson. 



The specimen is remarkable for the great relative size of the pars squamosa of 

 the temporal bone; being hardly equalled in this respect by that of the Camel or of 

 Oreodon. 



The ftimily to which Eucrotaphus belongs has not yet been ascertained with cer- 

 tainty, though from the form and proportions of the cranium being so very much 

 like those of Oreodon, I suspect it to have appertained to the ruminantia. 



Coincidentally, Dr. Owen's collection contains the portion of a cranium corre- 

 sponding to that just indicated; but it belongs to a diflferent and rather larger 

 species. 



Besides the foregoing, no specimens have been discovered, which can be ascer- 

 tained to belong to Eucrotaphus. From the similarity in construction of the 

 cranium proper of the latter and of Oreodoii, and from the decided ruminant cha- 

 racters of the specimens upon which Agriochoerus has been proposed, with the 

 relations of size which these bear to those of Eucrotaphus, I suspect the latter two 

 are in reality the same genus. 



To the smaller species of Eiicrotaphus, the head of which was about the size of that 

 of Oreodon Culhertsonii, the name EucrotapJiun Jaclsoni was given in honor of my 

 much esteemed and distinguished friend Dr. Samuel Jackson, Professor of the In- 

 stitutes of Medicine in the University of Pennsylvania. 



For the second species the name Eucrotaphus auritus is proposed, from the rela- 

 tively larger size of the auditory bullte. 



It is unnecessary to describe in detail the specimens upon which the two species 

 are foimded, for they agree so closely with the corresponding portion of the 

 skull of Oreodon, that it is sufficient to point out the peculiarities of structure 

 which distinguish them from the latter and from each other. 



The lateral and upper ^iews of the cranium proper of Ena-ofaj/hus (PI. VII. 

 Figs. 1, 2, 4, 5,) are identical witli those of Oreodon, except, perhaps, the pars 

 squamosa is a trifling degree larger in the former, and the parietalia are rather 

 more depi-essed in advance and upon the course of the squamous suture. 



The outline of the base view (Figs. 3, 0), and the position of the foramina are 

 also the same as in Oreodon; but in Eucrotaphus, the glenoid articulation is rather 



