278 THE STUDY OF ANIMAL LIFE CHAP, xm 



Some, the last for example, are terrestrial, but usually 

 live in damp places ; most pass their youth at least in 

 fresh water ; none can endure saltness, and they are 

 therefore absent from almost all oceanic islands. 



The common British newts (Triton), and the often 

 brightly-coloured salamanders (Salamandra) have in 

 adult life no trace of gills ; the rice-eel (Amphiuma) 

 and the allied Menopoma lose their gills, but persistent 

 clefts indicate their position ; the blanched blind Proteus 

 from caves and the genus Menobranclms keep their gills 

 throughout life. The remarkable Axolotl from North 

 American lakes occurs in two forms, both of which may 

 bear young ; the one form (Axolotl) has persistent gills, 

 the other form (Amblystoma) loses them, and the change 

 from the Axolotl to the Amblystoma is sometimes induced 

 by scarcity of water. (See p. 390 and fig. 119.) 



The common frogs (Rana), the Surinam toad (Pipa), 

 the common toads (Bujo), and the tree-frogs (Hyla) 

 illustrate the tailless order Anura. In none of them is 

 there in adult life any trace of gills. 



The worm-like, limbless, burrowing Amphibians (Gym- 

 nophiona) must not be confused with the blind- or slow- 

 worms, which are lizards. There are only a few genera, 

 e.g. Siphonops, Epicrium, Ccecilia. There are small 

 calcareous scales concealed in transverse rows in the skin. 

 In some forms at least there are gills in the very young 

 stages before hatching, but they do not last. The eyes 

 are minute and covered with skin. 



The race of Amphibians began in the Devonian age, 

 and the quite extinct Labyrinthodonts (from Carboniferous 

 to Triassic) had dermal armour and were sometimes of 

 large size. 



Amphibians are naturally sluggish. For long periods 

 they can fast and lie dormant ; they can survive being 

 frozen quite stiff, and though tales of toads within stones 

 are mostly due to mistakes or fancies, there are some 

 authentic cases of prolonged imprisonment. 



Few are found far from water, and the gilled condition 

 of the young is skipped over only in a few cases. In the 

 black salamander (Salamandra atra) of the Alps, which 



