THK FISH-LIZARD, 341 



and lizards, tortoises, serpents, and frogs, are found. 

 The lias formations (a term corrupted from layers] , con- 

 sisting of strata in which an argillaceous character 

 prevails, stand next in series. In these we have animals 

 preserved in a fossil state, of a distinguishingly different 

 character from those of the inferior strata. We meet 

 with extended beds of pentacrinites, some inches in 

 thickness ; and their remains are often so very complete 

 that every part of the skeleton can be made out, although 

 so complicated that it cannot consist of less than 150,000 

 parts. In these formations we often find the curiously 

 beautiful remains of the ammonites, of which a great 

 variety have been discovered. Of the belemnites 

 animals furnished with the shell and the ink-bag of the 

 cuttle-fish, with which it darkened the water to hide 

 itself from enemies, numerous varieties have also been 

 disentombed, with the ink-bag so well preserved, that 

 the story of the remarkable fossil has been written with 

 its own ink. In addition to these we find nautili ; and 

 sixty species of extinct fishes have been described by 

 Agassiz from the lias of Lyine Regis alone. 



When these rocks were in the progress of formation, 

 there existed the ichthyosaurus, or fish-lizard, which 

 appears, in many respects, to have resembled the croco- 

 dile of the Nile. It was a predatory creature of enor- 

 mous power, and must have been the tyrant and terror 

 of the seas which it inhabited. Its alligator-like jaws, 

 its powerful eye, its fish-like fins, and turtle-like paddles, 

 were all formed to facilitate its progress as a destructive 

 minister. The plesiosaurus was, if possible, a still more 

 extraordinary creation. To the head of a lizard was 

 united an enormously long neck, a small and fish-like 

 body, and the tail of a crocodile : it appears formed for 

 existence in shallow waters, so that, when moving at 

 the bottom, it could lift its head above the surface for 

 air, or in search of its food. The flora of this period 



