80 S. W. Williston. 
and occupying nearly the whole extent of their margin and the 
upper half of their externo-superior surface, are the elongated and 
oval epipterygoids. They continue the aclivity of the pterygoid 
wings on the outer side a little more steeply, ending in an obtuse 
point a little back of the orbitosphenoid plates, which touches, but 
is not suturally united with, the parietals above. These epiptery- 
goids are broader in front, where they come in contact with each 
other over the pterygoids. The quadrates in the larger specimens, 
and also in one of the smaller, are preserved nearly or quite intact, and 
in their natural relations. They unite with four bones only, the ptery- 
goids by a very broad and loose union, as shown in Fig. 1, Plate IIT; 
with the outer ends of the paroccipitals, as also shown by the dotted 
lines in the same figure and in Plate IJ, Fig. 1, and by their 
posterior everted articular margin with the outer extremity of the 
postparietals and, much more extensively, with the “epiotics” near 
the cranial wall. The thin, expanded proximal plate of the quadrate, 
as shown in Fig. 1, Plate III, narrows into a distinct neck, chiefly 
by a groove which winds from the under side about the hind margin 
a little above the articular extremity. The notch thus formed is 
clearly the auditory notch, corresponding to the notch or foramen in 
the quadrate of the mosasaurs and lizards; and possibly also it 
corresponds with the so-called quadrate foramen of the Pelycosauria. 
Doubtless the Cotylosauria had a small external ear situated nearly 
as it is in the lizards, above the angle of the mandible. The artic- 
ular surface of the quadrate for the mandible is oblique to the plane 
of the bone, so as to look more nearly downward in the normal 
position of the quadrate. Its outer side projects into a rather narrow 
process, but does not touch, much less articulate with, the roof bones. 
The mandibles, in comparison with the skull, are stout and heavy 
bones, and amply attest the predaceous habits of the animals. They 
are slightly expanded in front, where they meet in short symphysis, 
heaviest and stoutest just back of the orbits and broadest also here. 
They are nearly straight or gently incurved anteriorly, turned in- 
wards in a broad curve behind. The splenial bones unite in a 
median symphysis in front and extend back nearly to the articular, 
leaving a broad, elongate open cavity on the inner side from imme- 
