364 FOOTLESS A3rPHIBIA. 



whicli, at an early period of tlieir existence, are thus 

 organized, and at different periods of their lives 

 possesrs both lungs and gills. Some of these, when 

 very young, have gills only, and, like fishes, respire 

 water : but as they advance in age, the gills become 

 obliterated and lungs are developed. 



Such are the Frogs, Toads, and Newts, called, 

 from this circumstance, Caducihranchiate* Amphihia, 

 or Amphibious animals with perishable gills. In 

 another group, the gills are persistent through life, 

 even after the lungs are completely formed, and, 

 of course, animals so provided can live indifferently, 

 either in the air or in water. These are called 

 Perenni'branchkde'\ Ampliihia, or Amphibious animals 

 with perennial or persistent gills. 



xVnimals of this description present many characters 

 in common : instead of being covered with scales, 

 their skin is naked, smooth, and often moist. Their 

 body is either depressed and squat as the Toad and 

 Frog, elongated like the Salamanders or Newts, or 

 worm-like as in the Caecilias. The head is flattened 

 and joined to the body, without the intervention of a 

 neck. They have no ribs, and their toes are not 

 furnished with claws or nails. 



The Amphibia thus distinguished ai-e classified as 

 follows : — 



Footless Amphibia {Apoda).^ 



The Amphibia, which, from tlieir total want of 

 limbs, have been termed A2)oda, so much resemble 

 snakes in their general form, and even in some 

 particulars of their internal structure, that Cuvier 

 arranged them with the serpents, and by the super- 

 ficial observer, they might almost be mistaken for 

 worms ; such are 



The Blind Worms {CseciUa).^ 



* Caduciis, easily falling ; branchise, gills, 



t Ferenms, perennial ; hmncliise, gills. 



X a, a, icithout ; ttovs, ttoSos, pons, podos, a foot— footless. 



§ Cseciis, Mind. 



