MONITORS. 113 



The whole surface of the body is covered with 

 tubercles, which do not overlap, but are most 

 frequently arranged in transverse series. Some 

 species have the scales of the back set with a 

 ring of small projecting points, the regularity of 

 which is highly ornamental. Those of the lower 

 parts are flat, lengthened, and somewhat six- 

 sided. There is no collar of great scales beneath 

 the neck, but there is a transverse fold of the 

 skin. 



The colours of these Lizards vary from black 

 to green more or less deep, with spots which 

 seem to depend on the tubercles, the tints of 

 which, variously grouped, present more or less re- 

 gular designs, resembling Mosaic work ; so that 

 the skin of the Monitors may be employed in the 

 arts like shagreen. 



The tongue, unlike that organ in the Families 

 we have described, is fleshy, and very extensile, 

 so that it can be thrown forth to a length double 

 that of the head. The greater part is cylindrical, 

 but the terminal fourth is split into two conical, 

 horny, very flexible points. When retracted, 

 more than half the length is encased in a sort 

 of sheath ; and the portion that remains exposed 

 is frequently tinged with bright colours, so as 

 to be easily distinguished by its hue, even when 

 not protruded. 



The Monitors are found in both hemispheres ; 

 and with the exception of Europe and North 

 America, neither of which have any, the species 

 are equally divided among the great divisions of 

 the globe: viz., four in Africa, four in Asia, 

 four in Australasia, and four in South America. 



These are divided into two groups, the ter- 



I 



