272 
PEOFESSOR H. G. SEELEY ON THE STRUCTURE, ORGANIZATION, 
have the bone chiefly on the occipital plate. It is about 8 milliins. in length and width, 
with the external margin slightly concave, and the inner border slightly convex. 
The bone which is anterior to the epi-otic is in contact with the external process of 
the parietal, and is hence named the squamosal. It is oblong, and inclined obliquely, 
downward, forward, and outward. Its inferior margin helps to define the posterior 
post-cjuadrate concavity of the skull. It is 1 centim. long and less than half as wide. 
Its superior anterior border helps to give attachment to a slender bone which extends 
from the external angle of the parietal to the malar, and forms the postero-inferior 
border of the orbit. That bone is about 1'2 centim. long and 2 millims. wide. Its 
inferior border is concave and helps to enclose a small oblong vacuity between it and 
tbe scjuamosal behind and the malar below. This vacuity might correspond with the 
position of the bone which I term supra-quadrate—the supra-temporal of Owen and 
some authors. Below the squamosal is the quadrate, which has already been shown in 
other species to be compressed from front to back. It descends as a vertical pedicle, 
which lies below the hinder part of the orbit, and has its chief extension below and 
behind the malar. It is well seen on the inner side of the jaw, where it sends a strong 
process inward and upward to the pterygoid bone, and its rounded distal articular end 
is exposed externally by fracture on the left side ; but it is otherwise completely 
hidden from view by the enormous quadrato-jugal bone, which is imperfect on the 
left side from being broken away. It is perfectly preserved on the right side, wdiere 
it extends downward, outward, and backward, terminating posteriorly in a tuberosity 
which terminates the semi-circular contour of the post-orbital excavation. The form 
of the bone is obliquely sub-quadrate, 1’4 centim. high, and about 1 centim. wide, wdth 
the posterior border concave, and the anterior border convex. It is convex from above 
downward, where the lower extremity is reflected inward, but does not descend to 
the articulation so as completely to hide the quadrate. It is remarkable that the 
quadrato-jugal has a, considerable extension behind the quadrate bone. 
The malar bone, which forms the inferior border of the orbit, is an irregular 
crescentic bone, which is concavely constricted in the middle, and is in contact with 
the maxillary bone below in front, where it tapers away to meet the lachrymal at the 
anterior corner of the orbit. On the corresponding posterior surfaces it meets the quad¬ 
rato-jugal below and the post-orbital behind. It contributes with the maxillary in front 
and the quadrato-jugal behind to define a concave and somewhat angular excavation 
of the contour of the head below the orbit. The malar extends behind the maxillary ; 
its length is 1'7 centim.; its depth at the middle constriction is 1 or 2 millims. 
The maxillary bone, as preserved, mea.sures 2T centims. on the right side, but 
appears to be shorter on the left. The surface of the bone is concave from front to 
back, and convex from above downward, where it is 8 millims. deep, with a superior 
convex contour. It extends back somewdiat beyond the alveolar border; and above 
tbe alveolar border it contains one or two comparatively large vascular foramina. 
There are six teeth in each maxillary bone. They difter in no wmy from similar teeth 
