DIVISIONS OF REPTILIA. 241 



common European Tortoise (Testudo Grceca) and the Indian 

 Tortoise (T. Indica), the last attaining a length of over three 

 feet. 



ORDER II. OPHIDIA (Gr. ophis, a serpent). This order in- 

 cludes most of the animals which would commonly be called 

 snakes or serpents, and is characterized by the following pecu- 

 liarities : The body is always more or less elongated, worm- 

 like or cylindrical, and the skin develops horny scales, but 

 never bony plates. There is never any breastbone (sternum), 

 nor pectoral arch, nor fore-limbs ; nor, as a rule, are there any 

 traces of hind-limbs. In a few cases, however, rudimentary 

 hind-limbs can be detected. The ribs are always very numer- 

 ous. The two halves of the lower jaw are composed of several 

 pieces each, and they are united to one another in front only 

 by ligaments and muscles (Fig. 120). Hooked, conical teeth 



FIG. 120. The Naja Hqje, a poisonous Snake of Egypt. 



are always present, but they are never lodged in distinct 

 sockets, and are only used to hold the prey, and not in masti- 

 cation. The lungs and other paired organs are often not sym- 

 metrical, one of each pair being usually smaller than the other, 

 or altogether absent. 



