JURASSIC PERIOD. 



443 



expansion more remarkable than that of Cephalopods. The true 

 Reptiles were represented by numerous Enaliosaurs (sea-saurians, p. 

 339), of higher grade than the Simosaurs of the Triassic, as is shown 

 in their solid bony skulls ; by Lacertians and Crocodilians, many of 

 which were 15 to 50 feet in length ; by great Dinosaurs, the highest 

 of Reptiles ; by Flying Saurians (Pterosaurs), having wings, much 

 like Bats ; by Turtles of several genera. 



(1.) Enaliosaurs or Swimming Saurians. — The more common 

 genera of Enaliosaurs are the Ichthyosaurus, Plesiosaurus and Plio- 

 saurus. The Ichthyosaurs (the name, from the Greek, signihying fish- 

 lizard) were gigantic animals, 10 to 40 feet long, having paddles some- 

 Fig. 811. 



Reptile. — Plesiosaurus macrocephalus ( X45). 



what like the Whale (Fig. 805), long head and jaws, numerous (in 

 some species 200) stout, conical, striated teeth (Fig. 808), an eye of 

 enormous dimensions (as shown in Fig. 806), thin, disk-shaped, bicon- 

 cave vertebrae (Figs. 807 a, 807 b). The I. communis, found in the 

 Lias of Lyme- Regis and elsewhere, was 28 or 30 feet long. 



The Plesiosaur (the name meaning allied to a Saurian), (Figs. 809, 



