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258 GENERAL ZOOLOGY 



THE BLUE-TAILED SKINK, Eumeces quinquilineatus 

 Linnaeus 



Self -maintenance. This little lizard hunts among vege- 

 tation for insects, which constitute its principal food. It 

 sometimes eats bird's eggs, young field mice, or other 

 animals of suitable size. It is well fitted to seek and cap- 

 ture food. Its sight is very acute. The sense of taste is 

 also well developed, for ill-flavored substances are often 

 spit out after being taken into the mouth. The claws on 

 the ends of the toes enable the skink to run up and down 

 the trunks of trees with great swiftness. Though the 

 mouth is provided with teeth for holding prey, the food 

 is not chewed, except enough to kill it, before being 

 swallowed. 



The digestive organs of the skink resemble those of other 

 vertebrates, but the respiratory, circulatory and excretory 

 systems are better adjusted to terrestrial life than those 

 of the land amphibians. There is no respiration except 

 through the lungs; the structure of these organs and their 

 associated parts is more specialized than are those of an 

 amphibian. There are little chambers on the inner wall 

 of the lungs which increase the surface exposed and no 

 large branches of the blood-vessels supply the skin. Air is 

 drawn into and expelled from the lungs largely by move- 

 ments of the ribs, whereas frogs and toads have no ribs, 

 but force air in by gulping movements of the throat. The 

 chief excretion product in a reptile is uric acid, which is 

 thrown off as a solid in fact, is insoluble in water and 

 is therefore more desirable for a terrestrial animal (which 

 needs to conserve its water) than urea, which requires 

 liquid for its elimination. 



As the skink grows the "skin" is shed from time to 

 time. The whole epidermis does not come away in one 

 piece, as in many snakes, but sloughs off in patches. 

 Preparation is made in the skin before shedding occurs 

 .and a softening takes place in a particular layer of the 



