224 



THE WOKLD OF LIFE 



B 



in size and shape, one from the Lower Lias of Warwickshire 

 being 22 feet long, but detached vertebra? sometimes indicate 



a much larger size. In 

 the older Triassic beds 

 smaller species are found 

 which were less completely 

 aquatic ; and these seem to 

 show an affinity to Am- 

 23hibia rather than to rep- 

 tiles, indicating that the 

 two aquatic orders may 

 have had independent ori- 

 gins. 



Still later, in the Cre- 

 taceous formation, there 

 were other aquatic reptiles 

 quite distinct from all the 

 preceding, and more al- 

 lied to our living lizards, 

 having well-formed swim- 

 ming feet, but snake-like 

 bodies. These serve to in- 

 dicate how completely the 

 ?'^-.?^-~?^S'H^,''''^ ^^^ and Hind (B) reptiles of the Secondary 



Paddles of Ichthyosaurus intermedius. ^ 



From Lower Lias of Lyme Regis. One-third CpOCh OCCUpicd the plaCC 

 nat. size. (B.M. Guide.) n^^ ^ ^ ,^ T\r 



now nlled by the J\lam- 

 malia, somewhat similar forms adapted for aquatic life being 

 again and again developed, just as the Mammalia subsequently 

 developed into otters, seals, manatees, porpoises, and whales. 



Order — Ornithosauria 



We come finally to one of the most remarkable developments 

 of reptilian life, the bird-lizards, more commonly known as 

 Pterodactyls, which accompanied all the other strange forms 

 of reptilian life in the Mesozoic period. They are first found 

 a little later than the earliest Dinosaurs, in the Lowc-r Lias of 



