JURASSIC AXIMALS. 



447 



called a bird-like reptile. Most agree, however, that it is a reptilian 

 bird. 



It is interesting to note the different ways in which the same func- 

 tion — that of flying — is effected in different animals, without violating 



Fig. 704.— Head of Archaeopteryx macroura (after Dames). 



the law of limb-structure. In the Bat the resisting plane is produced 

 by stretching a membrane between the enormously elongated palm and 

 finger-bones ; in the Pterodactyl only one finger is enormously en- 

 larged and elongated for this purpose ; in the Bird the same bones are 



A B C 



Fig. 705.-^4, Fore-limb of Bat; B, Bird; C, Archseopteryx; D, Pterodactyl. 



shortened and consolidated, and the resisting plane is got by the use 

 of feathers. This was the method also in the Archaeopteryx, but the 



