252 GEOLOGY. 



it had those powerful muscles which flying animals al- 

 ways have. Instead of the projecting keel which birds 

 have for the attachment of their large flying muscles, it 

 has a thin, flat breast-bone, like that of the sea-turtle of 

 the present day. For the full exposition of the subject 

 of arrangements for flying, I refer you to my Natural 

 History, 199 and 200. It may be added to the rea- 

 sons which Agassiz has given for his opinion that there 

 were, so far as we know, no insects of sufficient size to 

 be food for so large an animal. But, after all, there was 

 in the Pterodactyl an apparatus which might be used, to 

 some extent, in flying, though there were no muscles 

 competent to sustain flight for any length of time. We 

 must therefore conclude that it probably rose into the 

 air occasionally, very much as the flying-fish now does, 

 with, perhaps, a somewhat longer range of flight. 



357. Dinosaurs. There is a class of Jurassic land rep- 

 tiles called Dinosaurs, the name coming from two Greek 

 works, demos, terrible, and sauros, lizard. Two of these, 

 Megalosaur and HylaBosaur, are represented in Fig. 153. 



Fig. 153. 



Another is the Iguanodon, so called because it was like 

 the Iguana family of the present day, a notice of which 



