THE MESOZOIC AGES. 2il3 



portraits. Every text-book figures the well-known 

 types of the genera Ichthyosaurus and Plesiosaurus ; 

 we need scarcely, therefore, dwell on them, except to 

 state that the catalogues of British fossils include 

 eleven species of the former genus and eighteen of the 

 latter, We may, however, notice some of the less 

 familiar points of comparison of the two genera. 

 Both were aquatic, and probably marine. Both swam 

 by means of paddles ; both were carnivorous, and 

 probably fed principally upon fishes ; both were pro- 

 per reptiles, and breathed air, and had large and 

 capacious lungs. Yet with these points in common, 

 no two animals could have been more different in 

 detail. The Ichthyosaurus had an enormous head, 

 with powerful jaws, furnished with numerous and 

 strong teeth. Its great eyes, strengthened by a circle 

 of bony plates, exceeded in dimensions, and probably 

 in power of vision under water, those of any other 

 animal, recent or fossil. Its neck was short, its trunk 

 massive, with paddles or swimming limbs of compara- 

 tively small size, and a long tail, probably furnished 

 with a caudal fin or paddle for propulsion through the 

 water. The Plesiosaur, on the other hand, had a 

 small and delicate head, with slender teeth and small 

 eyes. Its neck, of great length and with numerous 

 joints, resembled the body of a serpent. Its trunk, 

 short, compact, and inflexible, was furnished with 

 large and strong paddles, and its tail was too short to 

 be of any service except for steering. Compared with 

 the Ichthyosaur, it was what the giraffe is to tha 



