EXPLANATION OF PLATE U. 
23 
Plate 11. V. I. p. 175. 
1. Side View of the head of an Ichthyosaurus, marking 
by corresponding letters, the analogies to Cuvier’s 
figures of the same bones in the liead of the Croco- 
dile. (Conybeare.) 
2- Posterior part of a lower jaw of Ichthyosaurus com- 
munis, in the Oxford Museum. (Conybeare.) 
— 7. Sections presented by the component bones of Fig. 
2 in fractured parts above each section. (Conybeare.) 
8. View of the lower Jaw of Ichthyosaurus seen from 
vodiles ; but as the horny scales of Fishes, and dermal hones of Cro- 
eodilean animals are preserved in the same Lias with the bones of 
Ichthyosauri, we may infer that if the latter animals had been fur- 
nished with any similar appendages, these would also have been pre- 
served, and long ere this discovered, among the numerous remains 
that have been so assiduously collected from the Lias. They would 
certainly have been found in the case of the individual now before 
ns, in which even the Epidermis and vessels of the Rete Mucosum 
have escaped destruction. 
Similar black patches of petrified skin are not unfreqnently found 
attached to the skeletons of Ichthyosauri from Lyme Regis, but no 
remains of any other soft parts of the body have yet been noticed. 
The preservation of the skin shews that a short interval only elapsed 
between the death of the animal, and its interment in the muddy se- 
iment of wliicb the Lias is composed. 
living reptiles, tlie Batrachians afford an example of an 
boneV” naked, having neither scales nor dermal 
In the case of Lizards and Crocodiles, the scaly, or bony coverings 
protect the skin from injui-y by friction against the hard substances 
wit which they are liable to come into contact upon the land; but 
c t e Ichthyosauri which lived exclusively in the sea, there would 
m to have been no more need of the protection of scales or 
ermal bones, than to the naked skin of Cetacea, 
n t e case of Plesiosauri also, tlie non-discovery of the remains 
any dermal appendages with the perfect skeletons of animals of 
skt* 1° a similar inference, that they too had a naked 
in- The same negative argument applies to the flying Reptile 
l-amily of Pterodactyles. 
