PRIMARY DIVISIONS OF THE CHELONIDES. 115 



luscous animals. The green turtle {^Chelonia mydas), so 

 weU kno^vn to epicures^ belongs to this group^ and is 

 abundant in the tropical latitudes of the Atlantic Ocean. 

 The logger-head turtle {Chelonia carettd), on the con- 

 trary, is nearly confined to the Mediterranean ; and al- 

 though its flesh is stated to be rank and disagreeable, we 

 can assert the contrary from personal experience : it is, 

 in fact, fully equal to that of the green turtle. This 

 group is very limited, there being only seven species of 

 the genus Chelonia, and one of Sphargis. The shells of 

 the different marine turtles are singularly varied : in some, 

 the scales are imbricated, or laid over each other in the 

 manner of tiles ,• in others, they are fixed, with their 

 sides joining each other in the same manner as we see 

 in the land tortoises ; while in the Sphargis, or coriaceous 

 turtle, the shell is covered by a thick leather-like skin. 

 This latter structure is very important, because it shows 

 us plainly which group succeeds in the scale of nature. 

 The coriaceous turtle grows to an immense size, and has 

 been captured on the British coast. 



(118.) The next group is formed of the Trionicidce, 

 or soft tortoises. They derive this name from the shell 

 being thin and soft ; they have in fact no external plates, 

 both sides of the body being covered with a cartila'gin- 

 ous skin, through which, when dry, the rugged and 

 granulated structure of the ribs is seen. The horn of 

 their beak is clothed externally with fleshy lips ; and 

 their nose, unlike the other tortoises, is prolonged into a 

 smaU proboscis, having the nostrils at the tip {fig. 33.) : 

 the sternal plates, as in the sea tortoises, are partly in- 

 dented. The feet (fig. 34.) are palmate, and usually fur- 

 nished with five toes, but three only of them have sharp 

 and incurved claws. The tail is very short, and in some 

 almost wanting. As they live entirely in fresh water, 

 they are provided with an additional power of swimming 

 besides that of their palmated feet, for the loose skin of 

 their body forms a thin narrow flap round the edges of the 

 shell, and thus performs the office of a fin. They seem 

 to be entirely carnivorous, or at least the Indian species, 



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