843 
1872.] [Cope. 
SAUROCEPHALUS PHLEBOTOMUS. Cope. 
(Proceed. Am. Philos. Society, Nov., 1870. Hayden’s Geology, Wyoming, 
etc., 1871, p. 416.) 
Solomon River Region. Prof. Mudge. 
SAUROCEPHALUS ARAPAHOVIUS. Cope. 
Established on a portion of a maxillary bone, with a part of a suture, 
perhaps for attachment to a supernumerary maxillary. The size of the 
species is nearly that of S. lanciformis, and the crowns of the teeth are 
rather short, as in that species, and less elongate than in S. phlebotomus. 
The teeth are very closely set, and the alveoli are separated by very nar- 
row septa. The crowns are expanded, so that the edges overlap in some 
cases. The form of these is much compressed, width about equal to 
height, the edges convex and acute. The enamel is smooth and without 
facets. The roots are without the facets, shown by Leidy to exist in 
8. lanciformis, and appear to be longer than in that species, exceeding 
the length of the crown nearly four times. None are, however, perfectly 
exposed for complete measurement. As usual, there is a large foramen 
opposite each fang, below the inner alveolar margin, and between the 
latter and the series of foramina the surface is slightly convex and mi- 
nutely rugose. 
M. 
WEP OF DONC sx. aui vee secede be eke hese eae Nee cw aces 035 
Thickness at rugose band ......... see se reece eee e eee es 0055 
Total length of a tooth (?) ........e eee e cece ete e eee eee .02 
Length of @ CroWD... 1.2... 22. sees eee eeees dp os Ra RAR 0048 
Width eer es ee 0086 
Number, etc., in am inch. ...... ee cee eee cee eee eee eee ee eee 8. 
The size of this fish was probably about equal to that of Ichthyodectes 
anaides above described. Found loose on a cliff of blue shaly limestone, 
fifteen miles south of Fort Wallace, Kansas. 
PACHYRHIZODONTID &. 
This family of Physostomous fishes differs from the last in the nature 
of its dentition. Instead of elongate conic fangs sunk in deep alveoli, it 
has shorter and stouter fangs occupying alveoli, of which the inner side 
and part of the anterior posterior walls are incomplete. The teeth are, 
in fact, more or less pleurodont, but the extremity of the root is received 
into the conic fundus of the alveolus. 
The premaxillary bones are well developed, but the maxillaries are 
more so, and enter largely into the composition of the border of the 
mouth, There is a well-developed angle of the mandible, but no coro- 
noid bone is preserved in the specimens. The coronoid region is, how- 
ever, broken in all our specimens. The other characters of the family 
are not determinable from our imperfect materials. 
