222 CHARACTERS OF VERTEBRATE ANIMALS 



characteristic of fish and low types of other vertebrate groups. 

 In Reptiles generally it is most commonly the case that the centra 

 are concave in front but convex behind. 



2. Scale-footed Lizards make up a small family of snake- 

 like forms found in Australia, Tasmania, and New Guinea. The 

 fore-limbs are entirely wanting, though the hind-limbs are repre- 

 sented by lobe-like projections, but for which these creatures 

 might well be mistaken for serpents. An examination of their 

 structure, however, clearly shows that they are true lizards. 



The Common Scale-foot (Pygopus lepidopus] of Australia and 

 Tasmania may be mentioned as an example. 



3. The family of Agamoid Lizards is a very large one, limited 

 to the southern and eastern parts of the Old World. A typical 

 form is the Black -lipped Tree -Lizard (Calotes nigrilabris] of 

 Ceylon. Its body is of a metallic green tint, except the lips 

 and sides of the head, which are black. Among the more 

 remarkable members of the family are the so - called Flying 

 Lizards or Dragons of South Asia, small forms which certainly 

 do not live up to the latter name. These animals do not fly 

 in the proper sense of the word, but there is a parachute -like 

 expansion on each side of the body, supported by extensions of 

 some of the ribs, and capable of being folded up or extended. 

 The Malayan species (Draco volans] is well known. The 

 Thorny -tailed Lizards of Africa and Asia have the tail covered 

 with rings of spiny scales, and one species, the Dabb (Uromastix 

 spinipes], is common in Arabia, Egypt, and Crete. Australia 

 furnishes two remarkable species in the Frilled Lizard (Chlamy- 

 dosaurus Kingi), which has the habit of walking about on its 

 hind-legs, and the Moloch (Moloch horridus), covered with large 

 thorny spines. 



4. The Iguanas are, with few exceptions, found in the warmer 

 parts of America and the West Indies. The Common Iguana 

 (Iguana tuberculata) is a good type of the family, and the promi- 

 nent toothed ridge running down the middle of the back is a 

 characteristic feature. It is a vegetarian and lives mostly in 

 trees, but is also a very active swimmer. It may attain a length 

 of over 4 feet, which includes, however, the exceedingly long tail. 

 One of the most interesting members of the family is the Gala- 

 pagos Sea- Lizard (Amblyrhynchus cristat^ls\ the only known 

 marine member of its order. In size it rather exceeds the 



