342 
Cope.] {Jan. 5, 
ICHTHYODECTES MULTIDENTATUS. Cope. sp. noy. 
Here we have again the convex premavillary of the larger species, with 
more numerous (12) teeth than in any other of the genus. These in- 
crease in size to the first three, the last being small. The second and 
third are about equally prominent, and more so than the first. The bone 
is much contracted above, there being an excavation on the anterior 
border and contraction from behind. The superior edge is thin, and 
without trace of articular surface. Alveolar edge somewhat rugose. The 
maxillary is both narrow and thin, but is only partially preserved. It 
bears five teeth on M. .01. One of these, with complete crown, displays 
a longitudinal angle on the antero-interior face. 
No other remains were preserved. 
M. 
Lienru Ole premumllanyec ys.) ogi ty. ere are 0.089 
Depth i (OOMQUGIT : Fries Paes Ph Or +023 
HONS Ol POOUN LMG. iis VS s, HG ts eels fess oe 025 
From near Fossil Spring, W. Kansas. 
SAUROCEPHALUS. Harlan. 
Leidy has pointed out the mode of implantation of the teeth in the 
typical species of this genus. The mode of succession of the teeth has 
not yet been indicated, but is well displayed in a specimen of the jaw of 
S. arapahovius, Cope. It is known, from Harlan’s description, that a 
large foramen issues on the inner wall of the jaw, opposite each root. 
The fractured ends of the specimen exhibit the course of the canal which 
issues at this foramen. It turns abruptly downwards between the inner 
wall of the jaw and the fang of the functional tooth, and not far from 
the foramen. Its course is interrupted by the crown of the successional 
tooth. This is situated obliquely as regards the long axis of the jaw. 
It is thus plain that, the successional appearance of teeth is different 
in this genus from what I have described in the two genera preceding. 
In them the foramen is wanting, and the young crown rises within 
the pulp cavity of the functional teeth, as in the Crocodilia. In 
this genus, on the other hand, it is developed outside of the pulp 
cavity and fang of the old tooth, and takes its place as in many 
Lacertilia and in the Pythonomorpha, by exciting the absorption of the 
latter. The obconic form of these fangs in Saurocephalus is appropriate 
to such a succession, and their great length seems to preclude the nutri- 
tion of the young tooth from their bases. The use of the foramina on 
the inner face of the jaw is thus made apparent, viz., the nutrition of the 
successional teeth from without. I cannot trace the canal below the 
crown of the young tooth to the base of the pulp cavity of the old tooth ; 
and there are canals in the jaw, below the latter, one of which probably 
carried the dental artery. 
Species of this genus are less abundant in the part of Kansas examined 
by me than those of the preceding genera. Two only have been observed 
up to the present time, as follows : 
