238 PERMIAN FOSSILS. 
Genus Zhecodontosaurus, Riley and Stutchbury. 
“The genus Zhecodontosaurus is founded on the structure of the teeth, and their 
having been deposited in distinct alveoli.”’ In these characters it is allied to the 
typical Varanian Monitors; but with this difference, that the teeth are “imbedded in 
distinct sockets; to this condition, however, the Varani, among the squamate Saurians> 
make an approach in the shallow cavities containing the base of the teeth along the 
bottom of the alveolar groove. 
“In the ancient extinct genus in question the sockets are deeper, and the inner 
alveolar wall is nearly as high as the outer one; the teeth are arranged in a close-set 
series, slightly decreasing in size towards the posterior part of the jaw; each ramus of 
the lower jaw is supposed to have contained twenty-one teeth. These are conical, 
rather slender, compressed and acutely pointed, with an anterior and posterior finely- 
serrated edge, the serratures being directed towards the apex of the tooth, as in the 
genus Rhopalodon of G. Fischer; the outer surface is more convex than in the inner 
one; the apex is slightly recurved; the base of the crown contracts a little to form 
the fang, which is sub-cylindrical. The pulp-cavity remains open in the base of the 
crown. In their microscopic structure, the teeth of Zhecodontosaurus closely correspond 
with that of the teeth of the Varanus, Momtor, and Megalosaurus. The body of the 
tooth consists of compact dentine, in which the calcigerous tubes diverge from 
an open pulp-cavity at nearly right angles to the surface of the tooth; they form a 
slight curve at their origin, with the concavity directed towards the base of the tooth ; 
then proceed straight, and at the periphery bend upwards in the contrary direction. 
The diameter of the calcigerous tube is ;;4,,th of an inch; the breadth of the 
interspace of the tubes is =, of an inch. ‘The crown of the tooth is invested with a 
simple coat of enamel.” 
“The microscopic examination of the structure of the teeth, which I have been 
enabled to make by the kindness of Mr. Stutchbury, satisfactorily establishes the 
distinction between the Saurian of the Bristol conglomerate, and the reptiles of the 
later member of the new red sandstone system in Warwickshire, which I have 
described under the name of Labyrinthodon.” (Owen, Op. cit.) 
THECODONTOSAURUS ANTIQUUS, fizley and Stutchbury. 
Saurian, Williams. Proceedings of the Geol. Soc. Lond., vol. ii, p. 112, 1834. 
TuEcopontosaurus, Riley and Stutchbury. Proceedings of the Geol. Soc. Lond., 
vol. 11, p. 398, 1836. 
1 Riley and Stutchbury Proceedings of the Geol. Soc., vol. ii, p. 398. 
