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Updated: June 22, 2025
In every form man has passed through, he left behind some old member or power and took on some new. He left his air-bladder and his gills and his fins with the fishes; he got his lungs from the dipnoans, the precursors of the amphibians, and from these last he got his four limbs; he left some part of his anatomy with the reptile, and took something in exchange, probably his flexible neck.
For Nevians are true amphibians. Their blood is cold; they use with equal comfort and efficiency gills and lungs for breathing; their scaly bodies are equally at home in the water or in the air; their broad, flat feet serve equally well for running about upon a solid surface or for driving their stream-lined bodies through the water at a pace few of our fishes can equal.
They were approximately equal in size, and each ship now wielded the theoretical ultimate of power for her mass; therefore neither could harm the other, furiously though each was trying. And more and more nearly they were approaching the red atmosphere of the world of the amphibians.
I may here remind the reader that various facts opposed to this view have already been given under reptiles, amphibians, fishes and lepidoptera. Mr.
There were as yet no vertebrates of any sort, not even fishes, far less amphibians, reptiles, birds, or mammals. The veritable giants of the Cambrian world were the crustaceans, and especially the trilobites, which, nevertheless, hardly exceeded in size a good big modern lobster.
"If the eggs of a mammal now differ very essentially from those of a reptile and of an amphibian because in their organization they represent the beginnings only of mammals, even as these represent only the beginnings of reptiles and amphibians, by how much more must they differ from those hypothetical single-celled amoebas which could as yet show no other characteristics than to reproduce amoebas of their own kind."
The Rays form a large tribe of cartilaginous fishes in which, although the skeleton is not osseous, the development of organs is so advanced that they would appear to be the highest of the class, approaching nearest to amphibians. They are easily distinguished from the sharks by their broad and flat body, the pectoral fins being expanded like wings on each side of the trunk.
The generality of this fact is quite remarkable: it holds good with almost all mammals, birds, amphibians, and fishes; also with many crustaceans, spiders, and some few insects, such as certain orthoptera and libellulae.
They abandoned the defensive system of warfare and boldly took up the offensive. No doubt, like their descendants, the belemnites were exceedingly active and voracious creatures. FISHES AND AMPHIBIANS. In the Triassic and Jurassic, little progress was made among the fishes, and the ganoid was still the leading type.
To the parents who desire to lead the child's mind through a long sequence of thought from the lower to the higher life, the amphibian affords an easy step in this ascending scale. And among amphibians that familiar and picturesque harbinger of spring, the frog, and his cousin the friendly toad, are the best adapted. Children are always interested in frogs because they jump so well.
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