TOUTOISES. 53 



able them to naovo either on the water or on land. In the 

 turtles, these limbs appear in the form of broad, flat, un- 

 divided paddles, well-adaY)ted for moving in the water, but 

 awkward as instruments of locomotion, even on the level, 

 sandy shores to which they resort at the breeding season. 



The tortoise has a fleshy tongue like that of a })arrot. 

 The brain is but slightly developed, scarcely filling the cavity 

 of the skull in the maiine species. At the same time, the 

 animal possesses great muscular irritaljility, and extreme 

 tenacity of life. All are oviparous, and bury their eggs, 

 which are hatched by the warmth of the sun. The water 

 tortoises, when seen below the surface, move like birds in the 

 air, the paddles flapping like wings. 



The order is divided into four groups : first, Chersians, or 

 the land tortoises ; second, the Elodians, or marsh tortoises ; 

 third, the Potamians, or river tortoises ; fourth, the Thalas- 

 sians, or sea tortoises, generally called turtles. These gTOups 

 are again variously subdivided. 



The waters of Tropical America abovmd with the second and 

 third families. The Elodians, found in the shallow pools of the 

 Amazonian Valley, swim with facilit}^, and move quickly over 

 the ground. They feed not only on vegetables, but prey on 

 living animals — river molluscs, and other water creatures. 



The Potamians, which are found in vast numbers in the 

 larger rivers, grow to a great size, — some weighing seventy 

 j)Ounds. They feed much as the last described. They swim 

 with ease, both on the suiface and at mid-watei'. The upper 

 part of the body is generally brown or gray, with regular 

 dotted spots ; while the under parts are pale white, rosy, and 

 bluish. When they seize their food, they dart out their heads 

 and long necks witli the rapidity of ari'ows, and l)ite sharply 



