576 REPTILES. 



Classification of Lacertilia. 



There are three main divisions : — [a) Geckones ; (b) Lacertse ; and 

 (c) Chamseleontes. 



(a) In the Geckos (Geckonidse) the vertebrae are biconcave or amphi- 

 ccelous, the tongue is short and fleshy, the eyelids are rudimentary, the 

 teeth are pleurodont, the toes bear numerous plaits, by means of which 

 they adhere to smooth surfaces, e.g. Platydactylus. 



(b) The Lacertae include numerous families, of which a few may be 

 noted. 



The Agamas (Agamidae) are aciodont lizards common in the Eastern 

 hemisphere. Examples. — Agama ; Draco, with the skin extended on 

 long prolongations of five or six posterior ribs ; Chlamydosaurus, an 

 Australian lizard, with a large scaled frill around the neck ; Moloch, 

 another Australian form bristling with sharp spikes. 



The Iguanas (Iguanidae) are pleurodont lizards, represented in the 

 warmer parts of the New World. Examples. — Iguana, an arboreal 

 lizard, with a large distensible dewlap ; Amblyrhynchus or Oreocephalus 

 cristatus, a marine lizard confined to the Galapagos Islands ; Basiliscus, 

 in S. Mexico, with none of the marvellous qualities of the mythological 

 basilisk ; Anolis, the American chamaeleon, with powers of rapid colour- 

 change ; Phrynosoma, the American "horned toad," with numerous 

 horny scales, and a collar of sharp spines suggesting in miniature that of 

 some of the extinct Reptiles. 



The slow - worms (Anguidae) are limbless lizards, with serpentine 

 body, long tail, rudimentary girdles, and sternum. The British species, 

 Anguis fragilis, is neither blind nor poisonous ; the tail breaks very 

 readily ; the young are hatched within the mother. 



The poisonous Mexican lizard (Heloderma suspectum) measures over 

 a foot in length, and is covered with bead-like scales. Its bite is 

 poisonous, and rapidly fatal to small Mammals. It is interesting to 

 find poisonous powers like those of many serpents exhibited by this 

 exceptional lizard. 



The water-lizards (Varanidae) are large semi-aquatic forms of carni- 

 vorous habit, most at home in Africa, but represented also in Asia and 

 Australia. The Monitor of the Nile, Varanus niloticus, may attain a 

 length of 5 or 6 ft., and is noteworthy because of its fondness for 

 the eggs and young of Crocodiles. 



The Amphisbaenidae are degenerate subterranean lizards, without 

 limbs, with rudimentary girdles, with no sternum, with small covered 

 eyes, with hardly any scales. The sooty Amphisbaena (A. fuliginosa), 

 at home in the warmer parts of S. America, is the commonest species. 



The Lacertidae are Old World acrodont lizards, such as Pseudopus 

 (Europe and S. Asia) ; Lacerta viridis, the green lizard of Jersey and 

 S. Europe ; L. agilis, the British gray lizard ; L. muralis, abundant 

 about ruins in S. Europe ; L. or Zootoca vivipara, the British scaly 

 lizard. 



The Scincidse are common in tropical countries, e.g. Scincus, Cyclodus,- 

 Seps, Acontias (without limbs). 



(c) The Chamaeleons (Chamaeleontidae) are very divergent lizards, 

 mostly African. There is one genus, Chanuzleo. The head and the body 



