100 



HIGH SCHOOL ZOOLOGY. 



(Snakes), and Crocodilia (Crococliles) are divided, frequently 

 differ more from each other anatomically, than do the orders of 

 the Birds. The orders themselves, therefore, present still less 

 in common with each other, so that the study of a type of each 

 is necessary to enable the student to grasp the structure of the 

 whole Class. Much attention has been devoted of late to a 

 New Zealand Lizard-like .animal, Hatteria, because of all the 

 living Reptiles it is the most primitive form, and most nearly 

 allied to some of the oldest fossil representatives of the Class. 

 Some reference may afterwards be made to this interesting 

 species, but we are obliged to select a more accessible form as 

 an introduction to the group. 



2. Although the Turtles in respect to their skeleton are really 

 a very highly-specialised gi'oup, yet we shall find in the soft 

 parts many structures which will remind us of the Urodela. 





Fig. 73— Snapping Turtle. Chelydra serpentina . J. 

 (After Brehm). 



The common Snapper (Chelydra serpentiitm. Fig. 73) one of 

 the least specialised, is a convenient stai-ting-point for the study 

 of the others, but the following description will apply almost 

 equally well to the little painted turtle {Chrysemys jncta). 



