1884.] • ( 519 [Cope. 



; identity with his 0. bullatus has already been surmised by Leidy (Report. 

 U. S. Geol. Survey Terrs., I, p. 318). 



Encrotaphus jacksoni pacificus Cope. 



This form is materially larger than the last named, equaling in dimen- 

 sions and resembling in general form the Eucrotaphus major Leidy, of 

 the White River beds. It is no doubt the form which has been identified 

 under that name by Leidy in his report on John Day Fossils in the Report 

 of the U. S. Geological Survey of the Territories, Vol. I. It is different 

 from that animal in the form and position of the paroccipital process, as 

 already pointed out. I have eight crania disengaged from the matrix 

 which agree in dimensions and other characters assigned to this sub-spe- 

 cies. In one of them the paroccipital process presents an approach to the 

 form of that of the E. j. leptacanthus. A specimen from the White Buttes 

 of Central Dakota agrees with those from Oregon in all the essential 

 characters, and is the second one of the sub-species I have seen which is 

 not Oregonian. I have many crania of this sub-species not yet entirely 

 cleared of matrix. 



From John Day river and Crooked river, Oregon ; C. H. Sternberg and 

 J. L. Wortman ; White river of Nebraska, Mus. Princeton. 



Encrotaphus jacksoni leptacanthus Cope. 



This is the largest form of the genus, exceeding the typical E. major in 

 the length of the skull by 23 mm. It is thus far represented in my collec- 

 tion by two very perfect crania. There is considerable reason for antici- 

 pating that this form will turn out to be a valid species. Besides the pecu- 

 liar form of the paroccipital processes, the typical specimen presents the 

 following characters : 



The frontal region is flatter than in the two other sub-species, and is 

 concave on the median line in transverse section. This concavity is 

 probably partly abnormal. The profile of the sagittal crest instead of pre- 

 senting a gently convex outline, is concave, rising posteriorly. The lateral 

 occipital crests instead of being angulate are truncate behind, and the in- 

 ferior angle projects much beyond the vertical line of the occipital con- 

 dyles. As this part is broken off in most of my specimens of the E. j. 

 pacificus, I cannot decide as to its value. The inferior carina of the tym- 

 panic bone extends forwards to contact with the internal extremity of the 

 postglenoid process. It does the same in the Oregon specimen of E. j. 

 jacksoni, and in the Dakota specimen of the E. j. pacificus. In two of 

 the latter, from Oregon, where the part is cleaned, the keel does not extend 

 so far forwards or inwards. 



The typical specimen is from the John Day beds of John Day river, 

 Oregon, and was found by Jacob L. Wortman. 



Eucrotaphus major Leidy. 



Oreodon major Leidy, Ancient Fauna of Nebraska, 1853, p. 55, PI. IV, 

 fig. 6. Proceedings Academy Philadelphia, 1853, 398 ; 1856, 164 ; 1857, 89. 



