12 



CHELONIAD.E. 



This remarkable species is distinguislied from all the other 

 marine species, by the absence of horny plates upon the 

 body, head, and limbs ; Avhich, instead of them, are covered 

 by a tough leathery skin. In this respect it bears the 

 same relation to the family to which it belongs, that the 

 different species of Trionyx do to the fresh-water Tortoises 

 most nearly allied to them. This skin is perfectly smooth in 

 the adult ; but in young specimens it is covered with hard 

 tubercles. The head is more acute than in the other species 

 of marine Turtles : it is somewhat triangular when viewed 

 from above, the part anterior to the eyes being narrowed ; 

 the jaws are of immense strength, and the edges very sharp ; 

 the upper one has three remarkable notches, one in the cen- 

 tre, which is angular, and one on each side at a short distance 

 from the former, which are rounded. The lower jaw is 

 scarcely sinuated at the margin, and the point is very acute, 

 and somewhat hooked, corresponding with the central notch 

 of the upper. The nostrils are small, and perfectly circular. 

 The eyes rather large, opening nearly vertically, particularly 

 in the younger specimens. The view of the head here given 



is from a very large individual, of which the head and extre- 

 mities are in my collection. The carapax, or dorsal shell, 

 has seven distinct raised carinse, or ridges, which in the adult 

 are sharp, and slightly toothed : in the young they are 

 rounded, and composed of a number of round obtuse tuber- 



