42 MONITORS. [CH. I 



World family is that of the Monitors (Varanidae) ; there 

 are a large number of species which range over the 

 Oriental, Ethiopian and Australian regions ; the group 

 comprises some of the largest of lizards, arid some of them, 

 such as the Nilotic Monitor which lives upon the eggs and 

 young of the Crocodile, are aquatic in their mode of life. 

 The structure of the Monitors is such as to separate them 

 very widely from other lizards ; but they have no 

 particular relationship, as was at one time held, to the 

 peculiar American family of the Teiid;e, of which the 

 Teguexin is an example. The Lacertidaa are also a 

 peculiarly Old World family. To them belong two out of 

 the four indigenous lizards of this country. The fourth, 

 the Blind worm, is the representative of the family 

 Anguidae. The most limited range of any family is 

 afforded by the Helodermatidae, containing but one genus, 

 Heloderma, the Gila monster of the state of Arizona. 

 With one possible exception, it is the only poisonous 

 lizard. Australia has one peculiar family of lizards, the 

 Pygopodidae. America has two others besides those 

 mentioned, viz., Xenosauridae and Xanthusiidse. The 

 distribution of the lizards undoubtedly shows a marked 

 difference between the Old and New Worlds. Moreover the 

 Old World is more logically to be divided perpendicularly 

 than horizontally according to Dr Giinther. He would 

 divide the world into six regions, (1) America, (2) Africa 

 and Europe, (3) India and the Mantchurian sub-region of 

 the Pala^arctic, (4) Madagascar, (5) Tropical Pacific, and 

 (6) New Zealand, characterised of course as far as the 

 true lizards are concerned by negative characters. It is 



