(All except an outgrowth of one gill slit, whibsp;bees the passage of the ear and ear-drum.) The animal bsp;now live only in the air, but it must return at least to the edge of the water to lay its eggs and reprodubsp;its kind.
All the air-breathing vertebrata of this age of ss and plants belonged to the class amphibia.
They were nearly all of them forms related to the s of to-day, and some of them attained a siderable size.
They were land animals, it is true, but they were land animals needing to live in and near moist and sy places, and all the great trees of this period were equally amphibious in their habits.
None of them had yet developed fruits and eds of a kind that could fall on land and develop with the help only of subsp;moisture as dew and rain could bring.
They all had to shed their spores in water, it would em, if they were to germinate.
It is one of the most beautiful is of that beautiful sbsp;parative anatomy, to trabsp;the plex and wonderful adaptations of living things to the ies of existenbsp;in air.
All living things, plants and animals alike, are primarily water things.
For example all the higher vertebrated animals above the fishes, up to and including man, pass through a stage in their development in the egg or before birth in whibsp;they have gill slits whibsp;are obliterated before the young emerge.
The bare, water-washed eye of the fish is protected in the higher forms from drying up by eyelids and glands whibsp;crete moisture.
The weaker sound vibrations of air ate an ear-drum.
In nearly every an of the body similar modifications and adaptations are to be detected, similar patgs-up to meet aerial ditions.
This Carboniferous age, this age of the amphibia, was an age of life in the ss and lagoons and on the low banks among the waters.
Thus far life had now extended.
The hills and high lands were still quite barren and lifeless.
Life had learnt to breathe air indeed, but it still had its roots in its native water; it still had to return to the water to reprodubsp;its kind.