280 



ZOOLOGY 



APPENDIX TO CHAPTER XVIII 



KEY TO THE FOUR OKDEKS OF REPTILES 



Trunk enclosed in a case composed of a dorsal and 

 a ventral shield (carapace and plastron) ; jaws 



without teeth ."'-.. Chelonia 



Without encasing shields ; teeth on jaws. 

 ?>i. Teeth in special cups or alveoli ; 4 legs ; 



cloacal opening a longitudinal slit .. ' . Crocodilina 

 &:>. Teeth not in special alveoli ; cloacal opening a 



transverse slit. 

 Ci. Shoulder girdle and sternum present ; 



eyelids usually present . . . Sauna, 



c-j. Shoulder girdle and sternum absent ; eye- 

 lids absent ; no feet . _. . . Ophidia 



