134 Jo dal, Jd aS; 
by the basisphenoid. It is roofed by the premaxille, a little of the 
maxille, the palatines, pterygoids, and vomers. Three openings 
pierce it—the paired internal nares and the presphenoidal opening. 
Behind it medially lies the strong framework of the brain-case, and 
on either side the large depressions inclosed by the quadrates, 
quadrato-jugals, and jugals, and pierced by the lateral temporal fosse 
and the quadrate foramina. 
Where contained by the premaxille the trough is bounded on 
either side by a rounded ridge outside of which are the teeth sockets. 
This ridge has already been mentioned 
in connection with the general descrip- 
tion of the skull. 
The end of the snout bears two 
large teeth on each bone, then a 
smaller one, separated from them by 
about one-fourth of aninch. Between 
this tooth and its nearest neighbor 
to the rear is a space of three-fourths 
Fic. 4.—Cross-section of pre- 
SH inches Homescemny inch. The other teeth are closely set-— 
of snout. not over one-eighth inch apart in most 
cases—and increase in size gradu- 
ally from front to rear. The total number on each side is thirty-six, 
of which twenty are on the premaxilla, the remainder on the maxilla. 
With one exception all the teeth have been lost and the sockets filled 
with the sandstone matrix. The single tooth which remains is the 
second from the rear. It has been somewhat flattened by crushing, 
but its average cross-section is seven-sixteenths inch. It contains 
within its cavity a younger small tooth. The teeth of this specimen 
were apparently all of circular cross-section, resembling those of 
Fraas’s Mystriosuchus rather than those of von Meyer’s Belodon. 
They must have pointed obliquely outward. 
The premaxilla extends somewhat farther back on the under 
surface than above, as in the former region it has a length of eighteen 
and one-half inches. Along the last six inches of this distance it is 
excluded from the margin of the jaw by the maxilla. 
Masxilla.—On its lower side the maxilla presents a flat surface 
from which spring the rather large teeth of this portion of the jaw. 
