428 



THE GENERAL PRINCIPLES OF ZOOLOGY 



tute the order of flying reptiles. The skull resembled that of a 

 bird in general shape (Fig. 407); teeth were present in some, 



while others appear to 

 have had a hornv beak ; 

 the neck was fairly long. 

 The bones of the outer- 

 '* most digit on the anterior 

 appendages were greatly 

 elongated, thus affording 

 attachment to a membrane 

 extending along the arm, 

 the side of the body, and 

 along the posterior ap- 

 pendage, forming a wing, 

 something like the wing 

 of a bat (Fig. 408). The 

 tail was in some cases 

 short, in others very long. 

 The resemblance to birds 

 is. very great in the struc- 

 Fig. 407. Pterodactyl™ spectabilis, a fossil flying ture, form, and arrange- 



reptiie ; three fourths of the natural size. (Aftervon .„ ,„» ~f tU hones and in 

 Mayer, from Parker and Harwell's Text-book.) 



the shape of the brain. 



which was decidedly avian. Those reptiles varied much in size ; 



most of them were not very large, but some had an expanse of 



wing of over six meters. They are found only in Jurassic and 



Cretaceous formations. 



The fifth order of reptiles, the Pythonomorpha (Gr. YlvOuv, 

 Python, and /xop(j)?], form), consisted of marine animals which 

 very rarely came to land; they had the body greatly elongated, 

 snakelike, at times attaining a length of about twenty-three 

 meters. The appendages were paddlelike, and in some cases 

 there were bony plates in the skin. They are found only in 

 the Cretaceous formations. 



The earliest known fossil bird is represented by a single genus 

 and a single species, Archceopteryx lithographica (Fig. 409), of 

 which two specimens have been found in the Jurassic rocks 

 of Bavaria. It had teeth in both jaws. The tail was long, o\ 

 many separate vertebras, and with feathers in a row on each 



