Here, however, the parallel with evolution ends, for the majority of 
mature amphibians, unlike the mammals, are incapable of breaking com¬ 
pletely with their aquatic mode of life. The reproduction of their kind 
can, as a rule, only be accomplished in a watery medium. So, back to 
the streams and ponds these amphibians must return to lay their eggs. Their 
cycle is completed. 
The amphibians of today are described and classified as follows: 
CLASS: 
AMPHIBIA — the amphibians, represented by about eighteen 
hundred living species of worm-like amphibians (coecilians), 
salamanders and newts, frogs and toads. All are backboned ani¬ 
mals, respiring chiefly through their skin. They have three- 
chambered hearts and, like reptiles, a variable body temperature 
that corresponds with the temperature of the surrounding air or 
water, hence they too are also called “cold-blooded.” In winter 
they hibernate. They are covered with a glandular skin, in some 
smooth, in others rough. They usually deposit their eggs in the 
water, and these gelatinous bodies after hatching, with but a few 
exceptions, pass through an aquatic larval existence before chang¬ 
ing into gillless adults. The eggs, unlike those laid by reptiles, are 
never covered with a calcareous shell. 
ORDERS: 
GYMNOPHIONA —the limbless, worm-like, short-tailed coecilians 
comprising some nineteen genera and fifty-odd species, generally 
distributed throughout the tropics with the exception of the island 
of Madagascar. 
CAUDATA — the four-limbed, tailed salamanders and newts, of which 
there are more than one hundred and fifty kinds distributed in 
most temperate and tropical countries of the earth. 
SAL1ENT1A —the long hind-limbed, tailless frogs and toads which 
number more than sixteen hundred species scattered throughout 
the temperate and tropical regions. 
In various parts of the world frogs and toads not only aid man by 
eliminating noxious, crop-destroying insects, but also serve as food. French- 
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