CHELONIA. y 



There are some Fresh -water Tortoises, on the contrary, whose 

 long tail and voluminous members cannot be completely retracted 

 within the shell. This approximates them to the following sub- 

 genera, and particularly to the Chelydes, and renders them conse- 

 quently worthy of distinction.(l) Such is, 



Test, serpentina, L.; Schoepf. pi. vi. (The Snapper.) Easily 

 recognised by its tail, which is nearly as long as its shell, and 

 bristled with sharp and dentated crests, and by its pyrami- 

 dically elevated plates. It is found in the warm parts of North 

 America, where it destroys numbers of fishes and aquatic birds, 

 wanders far from rivers, and sometimes weighs upwards of 

 twenty pounds. 



Chelonia, Brongn.(2) 



The envelope of the Sea Tortoises(3) is too small to receive their 

 head, and particularly their feet, which are very long (the anterior 

 ones most so,) and flattened into fins. The toes are all closely united 

 in the same membrane, the two first ones of each foot being alone 

 furnished with pointed nails, one or other of which at a certain age 

 is usually lost. The pieces of their sternum do not form a conti- 

 nuous plate, but are variously notched, leaving considerable inter- 

 vals which are filled with cartilage only. The ribs are narrowed and 

 separated from each other at their external extremities; the circum- 

 ference of the shell, however, is surrounded with a circle of pieces 

 corresponding to the ribs of the sternum. The temporal fossa is 

 covered above by an arch formed by the parietal and other bones, 

 so that the whole head is furnished with an uninterrupted osseous 

 helmet. The internal surface of the oesophagus is every where 

 armed with sharp cartilaginous points which incline towards the 

 stomach. 



Test, mydas, L.;(4) T. viridis, Schn. ; Lacep. I, 1 (The 

 Green Tortoise), is distinguished by its greenish plates, thirteen 

 in number, which are not arranged like tiles; those of the mid- 

 dle range are almost regular hexagons. It is found from six to 

 seven feet long, and weighing from seven to eight hundred 



(1) This subdivision has furnished M. Fitzinger with his genus Cheltdra, and 

 M. Fleming with that of Chelgnura. 



(2) Chelonia, from ;^sm3v. Merrem has preferred the barbarous name of Ca- 



HETTA. 



(3) Commonly, but absurdly, termed Turtle,- they might, with equal propriety, 

 be called Doves. <Sm. Ed. 



(4) This name of Jfyc^os was taken by Linnaeus from Niphus. Schneider con- 

 siders it as a corruption of tf^u;. 



Vol. ILB 



