45 8 MANUAL OF ZOOLOGY. 



is broad, somewhat triangular in shape, broadest at its 

 middle, and showing a very distinct line of demarcation 

 between the head and neck. The head, also is usually 

 covered with small scales, rarely interspersed with larger 

 plates or " scuta ; ' (fig. 198). Other well-known members 

 of this group are the Death Adder (Acanthophis tortor) 

 of Australia, the Horned Viper (Cerastes) of Africa, and 

 the Puff Adder (Clotho arietans) of the Cape of Good Hope. 

 The Colubrina include for the most part harmless snakes, but 

 together with these are some of the most deadly of all the 

 venomous snakes. In accordance with this they are often 

 divided into the three sections of the Innocua, Sitspecta, and 

 Venenosa. In the first of these sections (Innocud)^ the superior 

 maxillae are provided with solid teeth only, and there are no 

 fangs. In this section are the common Ringed Snake of Bri- 

 tain, and the Boas and Pythons of warm climates. The com- 

 mon Ringed Snake ( Coluber natrioc) of Britain is 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 (Bascanion constrictor), which attains a length 

 of from three to five feet, but is perfectly harmless, so far as 

 man is concerned. The Boidce or Boas and Pythons are the 

 largest of all living snakes, attaining a length of certainly over 

 twenty feet. Their bite is perfectly harmless, 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 con- 

 dition of a shapeless bolus, fit to be swallowed. In this way a 

 good-sized Python or Boa will certainly dispose of an animal 

 as large as a sheep or goat, and it is asserted that even human 

 beings may be devoured in this way by large individuals of the 

 family. The Boas and Pythons occur in both the Old and New 

 World, the Pythons, however, all belonging to the Old World, 

 and they are amongst the most formidable of all living Ophidians. 

 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. In all, also, the dental 

 apparatus is extremely powerful, giving a firm hold for the con- 

 striction of the prey. 



In the section Suspecta, in which there are, canaliculated 

 fangs placed far back on the superior maxillae, with smaller 

 solid teeth in front of them, are certain unimportant snakes, 

 partly aquatic and partly terrestrial in their habits, and all be- 

 longing to the Old World. 



