218 



VERTEBRATE ZOOLOGY 



tions are utterly fish-like, but the fundamental internal anatomy of 

 the creature is essentially reptilian. It seems probable that the ich- 

 thyosaurs were viviparous, as are some purely aquatic reptiles of 



FIG. 124. Group of Mesozoic Reptilia. A, Long-necked plesiosaur, Elas- 

 mosaurus; B, short-necked piesiosaur, Trinaciomerion; C, ichthyosaur, Bap- 

 lanodon; D, pterodactyl; E, "Ostrich" dinosaur, Struthiomimvs; F, carnivorous 

 dinosaur, Tyrannosavrus; G, giant herbivorous dinosaur, Brachiosaurus; fl, 

 hooded "duck-bill" dinosaur, Coryihosaurus. (Redrawn after Osborn.) 



to-day; for it is inconceivable that creatures so purely aquatic in 

 habits should come ashore to lay their eggs. 



