36 SEA TORTOISES. 



23. The FAMILY OF SEA TORTOISES, (Turtle) Ckelonia. 

 The Tortoises that live in the sea, differ from all others, both in 

 their conformation and habits. Their flattened paws, which are 



really paddles, are only suited for 

 Fig. 8. swimming, and their toes, which 

 are closely pressed together, and 

 enveloped in the same membrane, 

 are entirely immoveable. Only the 

 two first toes of each foot have 

 nails, and these fall off at a certain 

 time ; and the anterior extremities, 

 in place of being of nearly the same 

 length as the posterior, are more 

 than twice as long. The carapax 

 is arched and cordiform ; and near 

 the edge of this shell, the ribs are 

 not widened and soldered together, 

 and, as in the preceding family, the 

 sternum is in the form of a frame open in the centre. The 

 nostrils are not prolonged into a trunk, but are surmounted by 

 a fleshy mass, which acts like a valve, in closing these openings 

 when the animal puts its head under water. The edges of the 

 beak are very trenchant, and the upper mandible is hooked. 



29. These tortoises feed principally on marine plants, and only 

 leave the water in the laying season: they swim with great 

 facility, and they are sometimes met several hundred leagues from 

 land, floating on the surface of the sea : they appear to be able to 

 sleep in this way, and they also dive very well. At the laying 

 season, they leave their habitual haunts and resort to the shores 

 of some desert island, to deposit their eggs in holes which they 

 dig upon the beach. During the night the females leave the water 

 for the purpose of laying; they drag themselves on the beach 

 beyond the line of high tide, and with their anterior extremities 

 excavate a hole about two feet deep in which they deposit their 

 eggs in regular ranges, and cover them with sand, which they 

 level off so carefully as to leave scarcely a trace of their labour. 

 The operation over, they return immediately to the sea. The 

 number of eggs is very considerable; sometimes as many as two 

 hundred, and the laying is repeated two or three times a year. 

 After exposure to the sun for fifteen or twenty days, they burst, 

 and the young, which are not yet provided with shell, imme- 

 diately make for the sea. Generally, they find difficulty at first 



28. What are the characters of Sea Tortoises ? 

 2S). What are their habits ? 



