TORTOISES AND TURTLES. 383 



tionately much longer than in the adult; but, owing to tlie more rapid 

 growth of the body, this becomes gradually shorter. Young garials have the 

 body and tail ornamented with a number of oblique dark bands on a lighter 

 ground. Although the garial is commonly looked upon with suspicion, it 

 does not appear that it ever attacks man or the larger mammals. 



ORDER II.— CHELONIA. 

 Tortoises and Tuktles. 



The presence of a bony shell, in a more or less fully developed state — some- 

 times enclosing the whole body in a solid case, and in other cases reduced to 

 a kind of dish-cover on the back — is the grand distinguishing feature of the 

 tortoises and turtles, which collectively constitute the second great order of 

 reptiles. Indeed, so far as their bony framework is concerned, these strange 

 creatures may almost be described as reptiles turned inside out. For the 

 ribs, which are generally united with bony plates in the skin to form the 

 upper shell, or carapace, are actually ]ilaced outside both the blade-bones and 

 the haunch-bones ; while, when a shell is developed on the under surface of 

 the body, its front portion is formed by the equivalents of the collar-bones. 



The presence, in some form or other, of such a shell serves at once to 

 distinguish the Chelonians from all other living reptiles. In ordinary 

 tortoises and turtles the upper shell is firmly welded to the backbone; but 

 the under shell, or plastron, which may or may not be joined by its edges to 

 the sides of the carapace, is generally free from the internal skeleton. Ex- 

 ternally the shell is covered by a number of longitudinal rows of horny 

 shields, which can bo stripped off without much trouble, and then reveal the 

 underlying bony plates. Unfortunately for the ordinary student of natural 

 history, the form and mode of arrangement of these hidden bony plates are 

 of the utmost importance in the classification of many of these reptiles. 

 And as they are not shown in figures taken from specimens in the ordinaiy 

 condition, he must either refer to special works on the subject, or must visit 

 a good museum. Both the superficial horny shields and the underlying bony 

 plates have received special names ; and as some acquaintance with their 

 general mode of arrangement is absolutely essential to the study of these 

 reptiles, a brief reference to the subject must be made in this place. 



Taking any ordinary Chelonian, such as the common Greek tortoise of our 

 gardens, we find the following general arrangement obtaining in the horny 

 shields. Along the middle of the upper shell runs a single series of five 

 large symmetrical shields known as the vertebrals. On each side these are 

 flanked by a series of still larger shields, usually also five in number, termed 

 the costals. The edges of the upper shell are formed by a numerous series 

 of much smaller marginal shields, which in those forms with a complete shell 

 overlap the middle of the sides, and thus come on to the plastron. At the 

 middle of the front edge of the carapace there is very generally a small un- 

 paired shield known as the nuchal ; while the term caudal is applied to the 

 corresponding single or double shield at the opposite end of the shell. On 

 the under surface, or plastron, we find six pairs of large shields, respectively 

 named, from front to back, the gular, humeral, pectoral, abdominal, femoral. 



