192 
ANIMAL ACTIVITIES. 
Taste. Special organs of taste are found on the 
tongue and on the membrane lining the mouth. 
Fic. 150.—Unstriped Muscie-fibres. 
Touch. The skin is well supplied 
with nerves, and there are special 
tactile areas. 
Classification. The frog belongs 
to the division of Vertebrata known 
as Amphibia or Batrachia. They 
receive their name Amphibia from 
the fact that the young live in water 
breathing by gills, while the adult 
forms breathe air. As might be ex- 
pected, there are exceptions to this 
general rule. The Amphibia are 
destitute of scales, the skin being 
perfectly naked, and in most cases 
provided with peculiar glands. They 
have no claws. The Amphibia differ 
from the fishes in having a connection 
between the mouth and nostrils, and 
also between mouth and ear. The 
heart in the adult has three chambers, 
a ventricle and two auricles. In the 
larva the heart is two-chambered. 
All live in fresh water. To this class 
belong the toads, frogs, and sala- 
manders. 
Reptiles. Questions similar to 
those used concerning the frog may 
be answered about turtles and snakes. 
Living turtles and snakes are easy to 
obtain and fairly easy to keep alive. 
A large box with glass sides covered 
with wire netting makes a good vi- 
varium. Sand and gravel and a dish 
of water should be kept in the bottom of this box. A 
little moss provides a carpet. 
The class Reptilia resemblesin many ways the 
