The males appear to be fewer in number than the females, or at least they come less frequently to the banks of rivers, where the females resort to deposit their eggs in hollows, which contain from fifty to sixty. The number varies according to the age of the females, which are less fruitful in proportion to their youth. The eggs are spherical, their shell is solid, but membranous or slightly calcareous.
Gym/sopa, Dum. and Bibr. (Triony.r, Geoff.; Aapidonectes, Wagler). Carapace with a cartilaginous circumference, very large, floating behind, and deprived of bone externally ; sternum too narrow behind to hide the limbs completely when the animal draws them up under the carapace. Trionyx and Teatudo ferox of authors.
G. spingerus. M. Lesueur states that towards the end of April, or most frequently in May, the females of this species seek out on the river banks sandy spots for the depo a of their eggs ; steeps of ten or fifteen feet elevation deter them not when they are choosing pieces exposed to the sun. Their eggs are spherical, and their shell is more fragile than that of the eggs of the species of Elodians living in the same waters ; their eggs amount to from fifty to sixty. M. Lesueur counted in the ovary twenty ready for laying, and a great quantity of others of variable dimensions, from that of a pin's head to the much greater volume which they attain when they are covered with their calcareous coat. The retreats of these tortoises are on rocks and on the trunks of trees overthrown in the river. They may be taken with book and line baited with a little fish ; they are very voracious, and bite their captors, so that the prudent cut off their heads. IL Leaueur was often bitten by those he had: they dart out their heads like lightning. The young begin to show themselves in July. The flesh of this species is very delicate.
Cr Thirovedii (Trionyx Congeticno, Cur.; T. Ifurunt. Gray) ; G. ocellatus (Trionyx orellattio,llardwick ; T. Ifortim, the young, Gray) ; O. linentsto (Trionyx "Egyptiacuo, var., Hertlw.; T. Indica., Gray); G. Jeronimo (Trinity% Jeronimo, Schweigg.); C. aubplanus (Trionyx subplanua, Geoff.) ; C. Evphraticus Euphraticua, Geoff.).
Cryptoptia, Dum. and Bibr. (Triony.r, WagL ; Ent yda, Gray).— Carapace with narrow cartilaginous borders aupnorting above the neck and behind the thighs small Irony pieces; sternum large, forming in front a moveable door or lid which can hermetically close the aperture of the osseous box. The posterior part of the sternum
furnished right and left with a cartilaginous operculurn, shutting the apertures which give passage to the hind feet ; there is a third operculum besides to stop the opening whence the tail issues.
C. gramma (Trionyx granoms, Schweigg.). It lives in fresh-water lakes. The flesh is eaten. C. Pmeyalcnsis.
Family IV. Thalaasiane, Sea-Tortoises, or Turtles. (C7aloninchr, Gray ; Coretteids, Fitzing.; Halyehelones, Ilitgen ; Oincopod Tortoises, Wagl.).
This family is at once distinguished from all the others by the comparatively depressed carapace and the long and broad paddles, the anterior of which are very much prolonged when compared with the posterior ones. Indeed their limbs are entirely so modified as to become swimming organs.
The Turtles hardly ever leave the sea excepting for the purpose of laying their eggs; but some accounts state that they will crawl up the shores of desert islands in the night, and clamber up the edges of isolated rocks far at Bea, for the purpose of browsing on certain favourite marine plants. They have been seen in smooth water no far as 700 or 800 leagues from the land, floating motionless on the surface of the sea as if they were dead, and it has been supposed that they are then asleep. They dive well, and can remain beneath the surface a long time, as might be expected from the extent and volume of their arbitrary lungs, capable of retaining and furnishing a sufficient quantity of air while they are submerged.
Messrs. Durneril and Bibron speak of the Potamians and Turtles as exceptions to the rest of the Chelonia, which, generally speaking, can produce no other sounds than hisses : we find however from Mr. Darwin's account above given, that the Great Land-Tortoises, the males at least, bellow loudly at the pairing semen. The cries of the Potamians and of some Thalassians have been noticed by observero, and especially those of the Coriaceous Turtle, or Sphargis. Individuals of this last genus, when hampered in nets or grievously wounded, have been heard to utter loud roars, from which they derive their name (eroaperyito), to roar, or cry loudly).