CHELONIA. 271 



The Teurapins, or Box-Tortoises, (Terrapene, Mcrrem ; Kinosteriion, Splx ; Cisluda, Fleming), — 

 The breast-plate of ■which is divided into two pieces by a moveable articulation, and which liave the 

 power of completely closing their carapace \vhen the head and limbs are withdrawn into it. 



Some have only the anterior segment of the breast-plate movL^able, as T. suhiiigra, Lin., and T. c/ausa, Sclitcff. ; 

 while in others both segments are equally mobile, as T. tricarinata, Schccff., and T. penm-t/tvanica, Id. 



There are some Fresh-water Tortoises, 



The Chei.ydrons {Chelt/dra, Pitzinger ; Ckclonura, Fleming;, — ■ 

 Which have a long tail and great limits, that cannot be quite withdrawn within their armour. Tlicy 

 approximate to some of the following genera, and more pai-ticularly to the Chelydes, and should rank 

 as a particular subdivision. 



Such is the Long-tailed Tortoise (T. serpenfina, Lm.), which is known by having- its tail almost as lone; as the 

 carapace, and beset with dentelated and pointed crests, and pyramidal scales. It inhabits the warm reK,iotts of 

 North America, is very destructive to lish and water-fo\vl, ascends far up the rivers, and sometimes attains a 

 weight of twenty pounds. 



The Turtles {Chelonia, Brongniart ; Caretta, Merrem) — 

 Have their envelope too small to receive the head, a.nd more especially the feet, which latter are 

 extremely elongated, (particularly those in front,) flattened to serve as oars, and have all their toes 

 closely united, and enveloped in the same membrane. The two first toes alone of eatdi foot 

 are furnished with pointed nails, and even these are apt to fall, one or the other of them, at a certain 

 age. The pieces which compose their plastrou do not form a continuous plate, but are variouiily 

 dentelated, and leave great intervals, which are occupied only by cartilage. Their ribs are narrowed, 

 and separate one from another at their external portion, but the entire circumference of the cara- 

 pace is occupied by a circle of pieces corresponding to sternal ribs. The temporal fossa is covered 

 over by an arch formed of the parietals and other bones, in such a manner that the whole head is 

 guarded by a continuous bony casque. The cesophagus is internally armed throughout with carti- 

 laginous points, and sharp tubercles directed towards the stomach. 



The Edible or Green Turtle (T. midas,\Aii.) is distinguished by its greenish scales, to the number of thirty, 

 wliich do not cover each other in the manner of tiles, and the medial of which are ranged in almost regular hexa- 

 gons. It attains a length of six or seven feet, and a weight of seven or eight hundred pounds. Its flesh supplies 

 ail agreeable viand, very wholesome to mariners traver^ng the torrid zone. It feeds in great troops upon the 

 algas in the deptlis of the ocean, and approaches the mouths of rivers to respire. Its (t^i^-^, which are deposited in 

 the sand where the sun may warm them, are very numerous, and line eating; but its shell is not employed in 

 manufactures. 



A neighbouring species {Ch. maculosa, Nobis,) has the middle plates twice as long as wide, and of a fulvous 

 colour, marked with great black spots ; and another (Ch. lac/iri/mata, Nobis,) has plates as in the preceding one, 

 but raised into a boss posteriorly, and black splashes upon the fuhous. The scales of both those are useful iu 

 numufactures. 



The Imbricated Turtle (T. imbricata), which is less than the green one, with a more lengthened muzzle and 

 dentelated jaws, and bearing thirteen yellowish and brown scales, which cover each other in the manner of dies, 

 furnishes the best iortoise-shfll employed in the arts; but its flesh is disagreeable and unwholesome, though the 

 eggs are very delicate. It inhabits the seas of hot climates. 



There are yet two species allied to the Imbricated Turtle, the Ch. virgata, Nobis, the scales of which are more 

 raised, and the medial equal, but with more pointed lateral angles, and radiating black lines ; and Ch. radiaia^ 

 Schjelf., Avhich merely differs from the last by having the hindmost of its middle scales wider, being perhaps a 

 mere variety. 



Finally, the Hawk-billed Turtle (T. caretta, Gm.) is more or less brown or rufous, with fifteen scales, the media] 

 of which have raised crests, more particularly towards the extremity; the point of the upper mandible is crookeii, 

 and the fore-feet longer and narrower than in the others, preserving also better-marked nails. It inhabits 

 several seas, and even the Mediterranean, subsists on Testacea, has bad flesh, and shell which is in low estima- 

 tion, but it furnishes an oil that burns welL 



Merrem has recently distinguished, as 



The Leatherbacks {Sphargis, lU. ; Coriudo, Fleming; DcrmocheUs, Lcsueur), — ■ 

 Those species which have no scales, but the carapace of which is invested with a sort of leather. 



Such is a large species of the Mediterranean [which has occurred two or three times on the Britis!^ sho'-csl 

 (T. cor ncia, Lin.), the carapace of which is oval, and pointed behind, with three prominent longitudinal ridges. 

 There is ariother in the Atlantic {Dermochelis atlantica, Lefevre]. 



' The Chelydes {Chelys, Dumeril ; Ma/amata, Merrem) — ■ 



Resemble the Fmydes by their feet and nails ; but their envelope is much too small to iiiulose tlio 



