1884.] B19 [Cope. 
identity with his 0. bullatus has already been surmised by Leidy (Report 
U. S. Geol. Survey Terrs., I, -p. 318). 
Bucrotaphus jacksoni pacificus Cope. 
This form is materially larger than the last named, equaling in dimen- 
sions and resembling in general form the Hucrotaphus 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 4. j. leptacanthus. A specimen from the White Buttes 
of Central Dakota agrees with those from Oregon in all the essential 
. chidracters, and is the second one of the sub-species I have seen which is 
not Oregonian. I have many crenia 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. 
Eucrotaphus jacksoni leptacanthus Cope. 
This is the largest form of the genus, exceeding the typical H. 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 ZH. 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 Z. j. 
jacksoni, and in the Dakota specimen of the Z. 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, Pl. IV, 
fig. 6, Proceedings Academy Philadelphia, 1853, 398 ; 1856, 164; 1857, 89. 
PROC. AMER. PHILOS. SOC. xxt. 116. 8N. PRINTED JUNE 9, 1884. 
