G4 SAURIA. 



This family contains the largest species of Lizards ; the greater part of them live in the 

 neighbourhood of large rivers, and are excellent swimmers, their long, compressed tail 

 serving as a propeller ; they are carnivorous, feeding on all the different water-animals and 

 on the eggs of birds, and likewise on those of other large reptiles. 



Their movements on land are not much less rapid than in the water. Several species 

 climb trees ; they are active during a part of the night. The external nasal opening leads 

 into a spacious cavity situated on the snout ; when the animal dives, it closes the nasal aper- 

 ture, and retaining a certain quantity of atmospheric air in that pouch, or rather in the 

 two pouches, it is enabled to remain under water for a prolonged period without the necessity 

 of rising to the surface in order to breathe. It is the same plan of structure as that with 

 which a large northern Seal [Cystophora horealis) is provided. 



They are found in the tropical parts of Africa, Asia, and Australia. The species of British 

 India belong to the following genera : — 



Nostrils an oblique slitj in, or nearly in, the middle between eye and 



extremity of snout Varanus, p. 64. 



Nostrils a more or less rounded opening, near the extremity of the snout . Hydrosaurus, p. 67. 



VARANUS. 



Varanus (part.), Merr. Amph. p. 58. 



The nostrils are an oblique slit, situated in, or nearly In, the middle 

 between the eye and the extremity of the snout. Scales elliptic, small ; 

 those on the back and on the sides not imbricate, each being surrounded by 

 a small, circular, granular fold. Tail with a low crest, formed by two or 

 four series of strongly keeled scales. Throat with a transverse fold. 



The species are the following : — ■ 



The free part of the middle fore toe (without claw) is half as long as the snout . . V. flavescens, p. 65. 



The free part of the middle fore toe (without claw) is much longer than the half 

 snout ; all the superciliary scales equally small. Ventral scales in 90 trans- 

 verse series. Neck without angular dark cross bauds V. dracana,"^. 65. 



The free part of the middle fore toe (without claw) is much longer than the half 

 snout ; all the superciliary scales equally small. Ventral scales in 105 trans- 

 verse series. Neck with dark angular cross bands, their points being directed 

 backwards V. lunatus, p. dQ. 



Superciliary scales small, with a series of larger ones along the middle . . . . V. nebulosus, p. 66. 



