366 THE STORY OF THE LIZARD. 



direct communication with the other. In the reptiles, however, this structure 

 is considerably modified, the arterial and venous blood finding- a communica- 

 tion either within or just outside the two ventricles, so that the blood is never 

 so perfectly aerated as in the higher animals. The blood is consequently 

 much colder than in the creatures where the oxygen obtains a freer access to 

 its particles. 



In consequence of this organization the whole character of the reptiles is 

 widely different from that of the higher animals. Dull sluggishness seems 

 tOi be the general character of a reptile, for though there are some species 

 which whisk about with lightning speed, and others, especially the larger 

 lizards, can be lashed into a state of terrific frenzy by love, rage or hunger, 

 their ordinary movements are inert, their gestures express noi feeling, and 

 their eyes, though bright, are stony, cold and passionless. Their mode of 

 feeding accords with the general habits of their bodies, and the process of 

 digestion is peculiarly slow. 



The most peculiar feature of the lizard is the facility with which it is 

 enabled to^ reproduce lost parts, and more especially the tail. In many lizards, 

 when handled, the tail breaks off without any rough usage, and in all or 

 nearly all it will readily come in two if pulled when the creature is seeking 

 to escape. Such missing portion of the tail is speedily reproduced, and 

 vv'hereas the scaling of the reproduced portion is like the original, in certain 

 ';ther forms this is by no means always the case. 



The water monitor is a native of those parts of Africa through which the 

 Nile, its favorite river, flows. 



The natives have a curious idea that it is hatched from crocodile's eggs 

 that have been laid on hot elevated spots, and that in process of time it be- 

 comes a crocodile. It is almost always found in the water, though it some- 

 times makes excursions on land in search of prey. To the natives it is a 

 most useful creature, being one of the appointed means for keeping the num- 

 bers of the crocodile within due bounds. It not only searches on land for the 

 eggs of the crocodile, and thus destroys great numbers before they are hatched, 

 but chases the young in the water, and devours them unless they can take 

 refuge under the adult of their own species, which the monitor will not dare 

 attack. 



When full grown, the water monitor attains a length of five or six feet. 

 The color of this species is olive-gray above, with blackish mottlings. The 

 head is gray, and, in the young animal, is marked with concentric rows of 

 white spots. Upon the back of the neck is a series of whitish yellow bands, of 



