74 



RiTER Tortoises. - 



-REPTILES.- 



-Marlse Tortoises. 



iu front and pointed, the bones composing it being 

 nearly naked. The jaws are horny, and covered with 

 a dependent, fleshy fold of skin resembling lips, and 

 which can cover the mouth. The nostrils are pro- 

 longed into a thin cylindrical tube, like a small mov- 

 able ptobcscis. Their carapace is very broad, and 

 nearly flat— fig. 23. It is soft, destitute of plates, and 

 covered with a flexible and cartilaginous sort of skin, 

 which extends all round the edges of the shell. These 



Fig. 23. 



edges are soft, and destitute of bones, and the ribs are 

 only united together and to the vertebrae above, whilst 

 they are separate below. The plastron or breastplate 

 is formed of a ring of bones, the centre not being ossi- 

 fied, and covered with a continuous skin. In adult 

 individuals these bones are furnished with rough 

 callosities on the prominent parts. The legs are short 

 and strong, and nearly of equal length behind and 

 before. 



None of the .ipecies are European, all that have as 

 yet been described being found in the large rivers and 

 deep lakes of the hotter portions of the globe. The 

 Nile and the Niger in Africa ; the Euphrates and 

 Ganges in Asia ; the Mississippi and Ohio in America, 

 are the principal places of abode of these animals. 

 Some of them attain a very large size. Pennant men- 

 tions individuals which weighed seventy pounds, and 

 he had one which lived in his possession for three 

 months that weighed twenty pounds, and was twenty 

 mches long in the shell. The neck measured thirteen 

 and a half inches in length. Individuals of the species 

 known as the Sewteree {Chitra ladka), a native of 

 the Ganges and other rivers of India, have been taken, 

 which, according to Dr. Cantor, weighed two hundred 

 and forty pounds. 



The River tortoises are in a great measure noctur- 

 nal animals. At night, when they consider themselves 

 free from danger, they come forth from the water to 

 stretch themselves out on the rocks in the little islets, 

 or take up a position on the trunks of trees overturned 

 in the rivers, but from which they precipitate them- 

 selves again into the water at the least noise or appear- 

 ance of danger. They are very voracious, and very 



nimble in pursuit of their prey. This consists of fishes, 

 reptiles, and mollusca, to which they are continually 

 giving chase, and which they pursue while swimming. 

 They in their turn are eagerly sought after hj man, for 

 their flesh is much esteemed as an article of food. In 

 order to catch them it is necessary to angle for them, 

 and to bait the hook with live fishes or other small 

 animals, to which motion must be given, for they will 

 not touch carrion or motionless prey. When they 

 seize their prey, or when they are called to defend 

 themselves, they dart their head and long neck forward 

 ^vith the rapidity of an arrow. They bite severely, 

 nor will they let go their hold without taking out the 

 piece seized. Their bite in consequence is much 

 dreaded by the fishermen, who generally cut off their 

 heads as soon as they are caught. The males appear 

 to be less numerous than the females, or at least they 

 are less frequently seen near the shore, the females - 

 being obliged to come to land to lay their eggs. These 

 they deposit in large holes which they dig out in the 

 sand, of sufficient size to hold fifty or sixty. They are 

 white, spherical, with a shell which is solid, but only 

 membranous or very slightly calcareous. 



THE TYESE OR SOFT TORTOISE OF THE NILE 

 {Tiionyx XUoticus) — represented in Plate 6, fig. 7 — 

 is a good illustration of the family. The carapace is 

 rather convex in the centre, oval or somewhat orbicular 

 in shape, covered with a skin which is coriaceous, 

 rough to the touch, and of a greenish colour or blackish- 

 brown, dotted with white or yellowish spots. The 

 breastplate is white, the rough callosities bluish. The 

 head is rather long, the jaws very strong, the lips 

 much developed and thick, and the tail is conical, 

 thick, and pointed. The Tyrse (for "by that name it 

 is known on the banks of the Nile) sometimes reaches 

 three feet in length. It inhabits the river Nile, but is 

 fouud in other rivers both of West and North Africa. 

 These animals are said to be very destructive to the 

 young crocodiles, devouring them in great numbers as 

 soon as hatched. 



This is the only species of Trionyx that inhabits the 

 Nile. Several other species are found in the rivers in 

 India and America, but we have not space to mention 

 them. 



MARINE TORTOISES ok TURTLES 

 {Clieloniidce). 



Of all the species of the Tortoise race, the Marine 

 species or Turtles are those which have more especially 

 attracted the attention of mankind from the earliest 

 periods of antiquity. Aristotle distinguishes them 

 from all the others by the term Thalassios {SaXaaaiog 

 or ^aXccT-r/o;), a term derived from the Greek, meaning 

 those animals which " frequent the sea." There are 

 two groups into which they may be divided, according 

 to the structure of the carapace, viz., those which have 

 this part of their shell, as well as their neck and feet, 

 covered with more or less hard and horny scales, and 

 those the carapace of which, and the external parts of 

 their body, are covered with a hard, thick, homy skin. 

 The structure of the limbs is one of the most remark- 

 able characters of this family, and distmguishes then.i 



