EEPTJLES. 193 



Turtle, and with these the animal moves rapidly through 

 the water, they being a pair of aquatic wings. On land, 



Fig. 157. Green Turtle. 



their walk is an awkward shuffle with these flippers. 

 They are very convenient instruments, however, in scoop- 

 ing out holes in the sand for their eggs. Nearly two 

 hundred eggs are laid in one nest. When laid, they are 

 covered up with the sand. The white of these eggs, 

 which are highly prized, does not harden in boiling. The 

 Green Turtle, the flesh of which is considered so great a 

 luxury, is common on the shores of most of the islands 

 of the East and West Indies. It has been known to 

 reach a weight of five or six hundred pounds. The tor- 

 toise-shell of commerce comes from the Hawksbill Tur- 

 tle. In this animal the horny plates are large, and are 

 arranged like shingles on a roof. 



319. Of the second order of Reptiles, the Crocodiles, 

 there are two groups the true Crocodiles, common to 

 both hemispheres, but most abundant in the Nile and 

 other African rivers, and in the Ganges ; and the Alliga- 

 tors, which are confined to America. There is not any 

 very great difference between them ; but the Crocodiles 

 are more thoroughly aquatic than the Alligators, and 



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