OPHIDIA. 629 



The Agamas (Agamidse) are acrodont lizards common in the Eastern 

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

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

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

 another Australian form bristling with sharp spikes. 



Iguanas (Iguanidse) 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 ; 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 (Anguidse) are limbless lizards, with serpentine 

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

 fragilis is not blind or poisonous, as popularly asserted ; the tail breaks 

 readily ; the young are hatched within the mother. 



The poisonous Mexican and Arizona lizards (Heloderma horridum 

 and H. suspectum] are over a foot in length, and are covered with 

 bead-like scales. 



The Varanidse are large carnivorous forms, most at home in Africa, but 

 represented also in Asia and Australia. The Monitor of the Nile, Varanus 

 niloticus, 5 or 6 ft. long, destroys eggs and young of Crocodiles. 



The Amphisbsenidse are degenerate subterranean lizards, without 

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

 eyes, with hardly any scales. 



The Lacertidae are Old World pleurodont lizards, such as Pseudopus 

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

 S. Europe. 



The Chamseleons (Chamaeleontidse) are very divergent lizards, 

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

 body are compressed ; the scales are minute ; the eyes are very large 

 and separately movable, 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 Chamaeleons exhibit numerous anatomical peculiarities. As in 

 the Amphisbsenas, there is no epipterygoid. The pterygoid does not 

 directly articulate with the quadrate, which is ankylosed to the adjacent 

 bones of the skull. 



Order 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 

 snakes in shape though they are very different in internal 



