Page:Encyclopædia Britannica, Ninth Edition, v. 23.djvu/479

Ocean (fig. 4). It is carnivorous, feeding on fish, molluscs, and crustaceans, and not esteemed as food, although it is eaten by the native fishermen. A great part of the turtle-oil which finds its way into the market is obtained from the Atlantic species of this genus; also tortoiseshell of an inferior quality is obtained from it.

Fig. 7.—The Matamata (Chelys fimbriata), with side view of head, and separate view of plastron.

The Green Turtle (fig. 5), which yields the materials for the celebrated soup, belongs to the genus Chelonia; it is distinguished from Caouana by having thirteen vertebral and costal shields only, which are not imbricate. These animals are herbivorous, feeding on marine Algx only; they occur in the Indo-Pacific and Atlantic; and, although several species have been distinguished, they all may possibly be referable to one only.

Fig. 8.—Upper View of the Turtle of the Euphrates (Trionyx euphratica).

The turtle imported into Europe comes chiefly from the West Indies. Instances are recorded of the flesh of this species having acquired poisonous qualities. The Hawksbill Turtle, Caretta (fig. 6), so named from its rather elongate and compressed curved upper jaw, does not reach the same size as the other turtles, and is readily recognized by the thirteen imbricate scutes of its carapace. It seems to be more abundant in the Indian than in the Atlantic Ocean, but is plentiful only in certain localities. As, however, these turtles always resort to the locality where they were born, or where they have been wont to propagate their kind, and as their capture is very profitable, they become scarcer and scarcer at places where they are known to have been abundant formerly.

Fig. 9.—Lower View of Trionyjc euphiatica.

If the plates of tortoiseshell are detached from the animal when decom position has set in, their colour becomes clouded and milky, and hence the cruel expedient is resorted to of suspending the turtle over fire till heat makes the shields start from the bony part of the carapace, after which the creature is permitted to escape to the water. There is no doubt that turtles thus allowed to escape to the water after such an operation may survive; but it is very improbable that the epidermal shields are ever sufficiently regenerated to be fit for use. At Celebes, whence the finest tortoiseshell is exported to China, the natives kill the turtle by blows on the head, and immerse the shell in boiling water to detach the plates; dry heat is only resorted to by the unskilful. The natives eat the flesh of this turtle, but it is unpalatable to Europeans; the eggs, however, are regarded as equal to those of the other turtles.

Of the family Chelydidse the most remarkable type is the Matamata, Chelys fitnbriata, a native of the Guianas and northern Brazil (fig. 7). In its strongly depressed and flat head, long tubelike snout, weak jaws, minute eyes, skinny tentacles, it bears a striking similarity to the Surinam toad, Pipa americana, which inhabits the same countries. The neck is very broad and depressed, and fringed with foliated tentacles, floating in the water like some vegetable growth, whilst the rough bossed carapace resembles a stone, an appearance which evidently is of as great use to this creature in escaping the observation of its enemies as in alluring to it unsuspicious animals on which it feeds.

The family of Carettochelydidx contains a single genus, Carettochelys, quite recently discovered in the Fly river, New Guinea, and exhibiting a remarkable combination of characters. Its limbs are formed very much like those of the marine turtles, whilst the shell lacks epidermic scutes, as in the Trionychidx.

In the freshwater turtles, or Trionychidae (figs. 8 and 9), the cara pace is reduced to a flat disk, which is covered with soft skin. The neck and limbs can be lodged under the broad skinny borders of the carapace; also the plastron is very imperfectly ossified, and sometimes dilated into large flexible lobes which may cover the limbs. The latter are much flattened and broadly webbed, and only the three inner toes armed with claws. The jaws are concealed under broad, fleshy lips, the nose projecting like a short proboscis. These turtles are carnivorous, and very ferocious; when they want to bite or seize their prey they project their neck and head with lightning rapidity. They are well known on the upper Nile, Euphrates, Ganges, Yangtse-kiang, and Mississippi, and, indeed, distributed over all the large fresh waters of the geographical regions to which