36 REPTILES AND BIRDS. 



The class of Reptiles is divided into three orders : — the Ophi- 

 dians, comprehending the Snakes ; the Saurians, the Lizards and 

 Crocodiles ; and the Chelonians, the Turtles and Tortoises. 



Ophidians. 



In Ophidians, commonly known under the name of Snakes, the 

 body is long, round, and straight. They have neither feet, fins, 

 nor other locomotive extremities. Their mouths are furnished with 

 pointed hooked teeth. In the Boas and Pythons the teeth are 

 slender, curved, bending backwards and inwards above their base of 

 attachment. In others each maxillary bone has a row of larger 

 ones, which gradually decrease in size as they are placed further 

 back. These teeth are not contiguous, being separated by consider- 

 able intervals. The smaller non-venomous Serpents, such as the 

 Colubridce, have two rows of teeth in the roof of their mouth. Each 

 maxillary and mandibular bone includes from twenty to twenty- 

 five teeth. In the Rattlesnakes and some other typical genera of 

 poisonous Snakes, the short maxillary bone only supports a single 

 perforated fang. Their lower jaw is highly distensible ; the opening 

 being longer than the skull. They have no neck ; their eyelids are 

 immovable ; their skin is coriaceous, highly extensible, and scaly 

 or granulous, covered with a thin caducous epidermis, which de- 

 taches itself in one entire piece, and is reproduced several times in 

 one year. Their movements are supple and varied. In conse- 

 quence of the sinuosity of their bodies — for, though scale-clad, 

 Snakes are without apparent means of progression — they make 

 their way with the utmost facility. 



The very numerous species of the genus inhabit either arid or 

 moist ground, bushes or trees. Some pass much of their time in 

 the water, and one family (that of the HydrophidcE) is exclusively 

 aquatic, even pelagic in the instance of one very widely diffused 

 species, the Pelamis bicolor. In the arboreal Snakes the tail is very 

 long, and highly prehensile ; in others, as the Vipers, it is short 

 and without any prehensility. In the Sea Snakes (Hydrophidtz), it is 

 laterally much compressed. Like other true Reptiles, Snakes abound 

 more especially in warm climates, and there are many kinds of them 

 in Australia ; but the order has not a single representative in New 

 Zealand. 



Most of the Snakes feed on living animals, only a few on birds' 

 eggs. Several kinds of them prey habitually on other Snakes, as 

 the genera Namadryas, Bungarns, and Elaps, even Psammophis 



