DIVISIONS OF REPTILIA. 



269 



(4.) The Colubrina comprise a great number of altogether innocuous Snakes, 

 in which the superior maxillie are provided with solid teeth only, and there 

 are no fangs. The head in the Colubrine Snakes is not much wider than the 

 neck, and is covered with large shields (fig. 193, B). The Colubrine Snakes 

 are cosmopolitan in their distribution, and an excellent example is the common 

 Ringed Snake (Colvher or Tropidonottis natrix) of Britain, a perfectly harmless 

 animal, which is commonly found in damp situations, and which lives mainly 

 upon frogs. Closely allied to this is the Black Snake {Dascanicm constrictor) 

 of North America, which attains a length of from three to five feet, but is 

 perfectly harmless, so far as man is concerned. 



(5.) The Pythonina comprise the well-known serpents termed the Boas, 

 Pythons, Anacondas, and Rock-snakes. The members of this group are the 

 largest of all living Snakes, attaining a length of certainly over twenty feet. 

 Their bite is not venomous, but they are nevertheless highly dangerous and 

 destructive animals, owing to their great size and enormous muscular power. 

 They seize their prey and coil themselves round it in numerous folds, by 

 tightening which they gradually reduce their victim to the condition of a 

 shapeless bolus, fit to be swallowed. The dental apparatus is extremely 

 powerful giving a firm hold for the constriction of the prey. They possess 

 rudimentary hind-limbs, terminating in horny anal spurs, which co-operate 

 with the prehensile tail in enabling the animal to suspend itself from trees. 

 The true Boas and Anacondas are South American, but the Pythons are 

 inhabitants of Southern Asia and Africa. 



Order III. Lacertilia. 



The third order of Reptiles is that of the LacerliUa, comprising all 

 the animals which are properly known as Lizards, together with 

 some snake - like creatures, such as the Blind- worm. They are 

 distinguished by the following characters : Usually there are two 



Fig. 194.— Iguana. 



pairs of well-developed limbs, but there may be only one pair, or all 

 the limbs may be rudimentary. In all cases, however, a scapular 

 arch is present. The vertebrae are usually hollow in front (jorocosl- 

 oiis), rarely hollow at both ends (amphiccelous). In no living Lacer- 



