Proterosauria and Ichthyosaur ia. 
31 
rows of well-developed low conical teeth closely set, and so 
arranged posteriorly as to form a deep longitudinal groove 
between two or more rows of teeth on each side for the reception 
of the marginal teeth of the mandible; these teeth are small 
and closely arranged, and wear by attrition with the upper 
teeth into a sharp cutting edge. There is also present on the 
inner side of the mandible a series of large and obtuse teeth. 
The tine specimen of Ilyperodapedon Gordoni exhibited from 
Elgin shows the head, neck, and body region, and some of the 
limb-bones in fair preservation, but the whole of the caudal 
region is absent. It was a terrestrial reptile, and attained a 
length of six or seven feet, and does not appear to have been 
armed with scutes or spines, but there are traces of wrinkled 
(skin) markings on the slab near the vertebrae. 
A much larger species, named Ilyperodapedon Huxleyi, has 
been obtained from the Triassic deposits of Maleri, India; of 
which a good series of the jaws is exhibited. It is computed to 
have attained a length of 17 ft. 
Prof. Huxley remarks (“Quart. Journ.” Geol. Soc., vol. xliii., 
1887) that this order had already attained its greatest 
degree of specialization as early as the Trias ; Ilyperodapedon 
being in all respects a more modified form than Sphenodon. It 
appears therefore to be probable that in the Permian, or perhaps 
still earlier, there must have existed Lizards differing less from 
the existing genus than either Ilyperodapedon or lihynchosaurus . 
Aphelosaurus, from the Permian, Prance, is also placed here. 
Prom the Trias of Elgin in Scotland, we have the very small 
Lacertian, the Leptopleurus (Telerpeton ) , not exceeding’ seven 
inches in length. 
The Saurosternon is another small form of Triassic lizard, 
from the reptiliferous sandstones of South Africa. 
Prom deposits of Oolitic age we have the Hommosaurus , 
Sapheosaurus , and Ardeosaurus from the Lithographic stone of 
Solenhofen. 
Order VI.— PROTEROSAURIA. 
To this order is referred a reptile named Proterosaurus 
Speneri , from the Permian “ Copper-slates ” of Thuringia. 
Though capable of progression on land, it was evidently of 
aquatic habits, feeding upon the Palceoniscidce and other fishes, 
which abounded in the seas of that period. 
Order VII.— ICHTHYOSAURIA (Fish-Lizards). 
These great marine carnivorous reptiles had very short 
necks (see Woodcut, Fig. 43), probably not visible at all ex- 
ternally; the vertebree are numerous and deeply biconcave (see 
Wall case, 
No. 7. 
Table-case, 
No. 12. 
Table-case, 
No. 12. 
Proterosau- 
rus. 
Table-case, 
No. 18. 
Wall-case, 
No. 14, 
Table-cases, 
Nos. 13 and 
14. 
