718 



GEOLOGY 



selves to sea life in another way (Fig. 490). The body took on a 

 form like that of a turtle, while the neck was elongate, giving ri.-e 

 to the epigrammatic description " the body of a turtle strung on a 



Fig. 489. Outline and skeleton of Ichthyosaurus quadriscissus. (After 



Jaekel.) 



Fig. 490. Skeleton of Plesiosaurus dolichodeirus Conyb. (Restored by 



Conybeare.) 



Fig. 491. Restoration of a Jurassic crocodilian, Geosaurus suevicus. (Fra.-is.) 



snake." Locomotion seems to have been chiefly dependent on the 

 paddles, though a fin-like adaptation of the tail existed in sonic. 

 The elongation of the neck was variable, the vertebra) of the neck 



