LOWER LIAS. 
13 
curve from the angle forward, horizontally, at first concave, then convex, towards 
the median line, where they meet without blending at the part fractured. It is 
not probable that the symphysis would be much prolonged beyond this point. 
The degree of convergence of the contour lines of the whole skull, both median 
and lateral, with the decreasing size of the anterior teeth, makes it more probable 
that but a small proportion of the muzzle is wanting in the present specimen 
(Tabs. IV and V). The analogy of the Iguanodon might be unsafe ground for 
inferring as short a symphysis mandibulee in Scelidosaurus, but it would accord 
with the other indications of such a proportion of the conjoined ends of the rami. 
Dentition. Tabs. IV and V. 
The specimen of Scelidosaurus here described has been buried and petrified 
with the mouth shut; there has been no dislocation of the under jaw, and the skull 
shows that the teeth of the upper jaw overlapped and concealed those of the lower. 
The crowns of both series were a little inclined inward, as shown at the fractured 
fore part (Tab. V, fig. 2, «, 6) ; this, with the similar inclination of the alveolar 
plates, produces a feature which reminds one of that of toothless anility, or of the 
effect of sucking in the cheeks, in man. 
The teeth are small, or of Lacertian proportions to the jaws ; they are nume- 
rous and close -set, implanted in sockets forming an uninterrupted series along the 
alveolar border. The fang is simple, and longer than the crown, presenting a full 
ellipse in transverse section, and projecting a little beyond the socket. In the 
upper jaw the crown (Tab. V, fig. 3) begins by bulging outward, with a smooth 
convexity, subsiding as it gradually expands, and dividing to be continued along the 
middle and the margins, with intervening concavities, producing an undulated 
surface across the broadest part of the crown. The marginal convexities or ridges 
terminate each in a point at the broadest part of the crown ; whence, the plate- 
shaped tooth having thinned off to an edge, this is divided on each side into five or 
six smaller points : these denticulate margins converge straight, at an angle rather 
less than a right one, to the apex of the tooth, which is formed by the pointed ter- 
mination of the median convexity. The crown is coated by a polished enamel, of 
jet blackness in the fossil, smooth under the lens upon the convexities, finely 
punctate in the hollows of the expanded part of the crow'n. The whole tooth in 
the upper jaw is very slightly bent backward, with as slight an oblique twist, 
making the hinder angle overlap the front angle of the crowm of the tooth behind. 
The inner surface of four of the hind teeth of the right ramus of the jaw 
shows a crown with a larger proportion of the serrated part, and with the borders 
less equal, the anterior one showing as many as nine points, and the expanded 
coronal surface is uniformly and gently convex. 
