96 BEITISH FOSSIL REPTILES. 



fractured on the left side ; on the right side it is entire. The malar bone (26) 

 begins anteriorly, in a pointed form, between the lacrymal and maxillary, 

 increases in depth as it extends beneath the orbit, sends up a process which 

 bifurcates to receive the point of the post-frontal in the cleft, and extends 

 backward and downward as a slightly convex and somewhat roughened plate, 

 which articulates by its lower convex, but somewhat irregular, border with the 

 squamosal (27). The posterior border of the malar presents a regular and well- 

 defined, concave curve. The chief peculiarity of the bone is its unusual vertical 

 extent posteriorly. The squamosal (Pis. 45, 46, 27) articulates with the 

 lower border of the malar, and expands to be articulated with the outer part of 

 the lower half of the tympanic (ib. 28). This deep and powerful arch of bone, 

 answering to the zygoma in mammals, afforded attachment to large, masseteric 

 muscles operating upon the lower jaw. Similar muscles may have been extended 

 between the ridges of the upper and lower jaws. 



The tympanic (partly exposed in PI. 45, 28) is a long bone, compressed from 

 before backward, almost vertical in position, with a slight forward bend, but 

 firmly wedged between the mastoid and par-occipital above and between the 

 squamosal and pterygoid below. The back part of the tympanic is convex 

 transversely at its inner half, concave at its outer half, where the margin is 

 slightly produced to join the upper part of the squamosal ; the inner part of 

 the tympanic is more extended where it is overlapped or abutted on by the 

 pterygoid. Below this expansion the tympanic becomes contracted and thickened, 

 forming a kind of neck to the transversely extended convex terminal condyle. 



In the vertical position and length of the tympanic, Scelidosa^lrus resembles 

 the Lacertia ; in its fixity and extent of its connections it resembles the 

 Grocodilia. 



The lower jaw includes in each ramus an articular (29), a surangular (30), a 

 coronoid (30'), an angular (31), a splenial (32), and a dentary (33) piece. 



The articular (PI. 47, fig. 2, 29) is situated in the inner side of the sur- 

 ano-ular (PL 45, 3o), and is thickened and projects inward to form the cavity 

 for the major part of the tympanic condyle, the outer border of which rests on 

 the surangular. This element, convex externally, presents a longitudinal ridge 

 near its upper part, which rises to join the posterior angle of the dentary element 

 in forming a low coronoid process. The angular (ib. 31) does not extend beyond 

 the surangular, but makes with it the angle of the lower jaw ; it grows in vertical 

 extent as it advances, is convex externally, unites with the dentary, and sends 

 forward from its lower part a pointed process between the dentary and splenial 

 elements. The splenial (PL 46, 32) makes a small appearance on the outer side of 

 the ramus, between the angular and dentary (33), but is chiefly visible as a broad, 

 smooth plate (PI. 47, fig. 2, 32), applied to the inner side of the dentary. The 



