74 THE STORY OF REPTILE LIFE. 



are shed periodically, generally in the form of 

 large flakes, but in certain instances they are 

 cast off in one piece, e.g. the Slow-worm (Anguis). 

 Skin-glands, as in the birds, are conspicuous by 

 their absence. The nearest approach to these 

 organs are certain pores in the anal and femoral 

 regions. Each of these pores perforates a scale, 

 and leads into a tubular invagination, or infolding, 

 which is lined with what are known as epidermal 

 cells, the breaking up of which produces a 

 yellowish debris, and by filling up the tube, 

 eventually appears at the surface in the shape of 

 .a little cone. Their use is unknown. 



The teeth present some interesting variations 

 in the nature of their attachment to the jaws. 

 Thus in some forms they become immovably 

 fixed, or ankylosed, by their bases with the 

 inside of the jaw, when the dentition is said to 

 pleurodent; in others, they are as firmly fixed 

 to the cutting edges of the jaws, forming then 

 an acrodent dentition. When the teeth are 

 lodged in sockets, as happens in the Crocodiles, 

 the dentition is described as thecodent. 



Most Lizards, like the Tuatera, are remarkable 

 for their ability to part company with their tails 

 .at a moment's notice. When threatened, this 

 organ, in many species, is temptingly raised as 

 if to invite or perhaps challenge the enemy to 

 seize it. If this be done it immediately breaks 

 off, leaving its owner to make good his escape 

 before his would-be captor has had time to 

 recover from his surprise. But these tail-less 

 lizards have no need to adopt the stratagem of 

 the fox in the fable, to persuade their fellows to 



