578 REPTILES. 



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 five or six feet, and is noteworthy because of its fondness for 

 the eggs and young of Crocodiles. 



The family Teiidae includes many New World pleurodont lizards, 

 mostly terrestrial in habit, for example, Teius tegnexim, the variegated 

 lizard of tropical Brazil, sometimes measuring five feet in length ; Ameiva 

 dorsalis, the common ground lizard of Jamaica. 



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 grey lizard, L. muralis, abundant about 

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



The Scincidae are common in tropical countries, e.g.> Scincus, 

 CycloduS) Seps, Acontias (without limbs), Oligosoma (abundant in the 

 Southern States of America), Eumeces (common in America and else- 

 where). 



The Chamseleons (Chamseleontidae) are very divergent lizards, mostly 

 African. There is one genus Chanuzlco. The head and the body are 

 compressed ; the scales are minute ; the eyes are very large and mov- 

 able, with circular eyelids pierced by a hole ; the tympanum is hidden ; 

 the tongue is club shaped and viscid ; the digits are divided into two 

 sets, and well adapted for prehension ; the tail is prehensile ; the power 

 of colour change is remarkably developed. 



The Chamseleons exhibit numerous anatomical peculiarities. As in the 

 Amphisbsenas, there is no epipterygoid nor interorbital septum. The 

 pterygoid does not directly articulate with the quadrate which is ankylosed 

 to the adjacent bones of the skull. 



Class OPHIDIA. Serpents or Snakes. 



The elongated limbless form of snakes seems at first sight 

 almost enough to define this order from other Reptiles, but 

 it must be carefully noticed that there are limbless lizards, 

 limbless amphibians, and limbless fishes, which resemble 

 serpents in shape though very different in internal structure. 

 For the external shape seems in great part an adaptation to 

 the mode of life, to the habit of creeping through crevices 

 or among obstacles. Even in the thin-bodied weasels is 

 there not some suggestion of the serpent ? Yet the limbless- 

 ness of serpents is not a merely superficial abortion, for there 

 is no pectoral girdle nor sternum, and never more than a 

 hint of a pelvis. 



The skin is covered with scales, which being simply folds 



