TADPOLES AND FROGS. 193 
Amphibia. The class includes many animals resem- 
bling toads and salamanders, besides the well-known 
turtles, snakes, crocodiles, and alligators. Among 
Reptiles the body is more or less completely covered 
Fic. 151.—A Frog’s Skeleton. 
by scales, and when there are any toes these are armed 
with claws. The heart is three-chambered, as in the 
case of Amphibians, except in alligators. The young 
do not breathe by gills as in Amphibia. The eggs are 
