78 EXTINCT MONSTERS 



be considered here. The species shown in Fig. 14 had rather a 

 large head. It is obvious that such a long slender neck as these 

 creatures had could not have supported a large head, like that 

 of the fish-lizard. Consequently, we find a striking contrast in 

 the skulls of the two forms. That of the Plesiosaur was short 



FIG. 13. Mandibles of Sea-lizards. A, Peloneustes philarchus (Seeley) ; from 

 the Oxford Clay. B, Thaumatosaurus itidicus (Lydekker) ; Upper Jurassic of India, 

 c, Plesiosaurus dolichodirus (Conybeare) ; from the Lower Lias, Lyme Regis. 



and stout, and therefore such as could easily be supported, as 

 well as rapidly moved about by the long slender neck. Thus 

 we find another simple illustration of the " law of correlation," 

 alluded to on p. 7. The teeth were set in distinct sockets, as 

 they are in crocodiles, to which animals there are also points 



