THE GREAT GROUPS OR "ORDERS" 



73 



The tortoises have shells over the body ; the croco- 

 dilians have plates placed edge to edge; the lizards 

 and serpents have overlapping scales; and on the 



Fig. 38.— Crocodiles. 



tnatera the skin is warty. The serpents are practically 

 legless'. "We know enough now to begin to learn some- 



Fig. 37.— Tuatera. 



