Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 29, 2025
It is therefore very interesting to find that in the other crustacean before mentioned, the squilla, the segmentation of the body is more completely preserved, and even the first three segments, which go to compose the head, remain permanently distinct. Such an obvious and unmistakeable serial repetition of parts does not obtain in the highest, or backboned animals, the Vertebrata.
I have said that the foot first appeared when the backboned creatures came out of the waters to live upon the dry land. See how the rat I mean our common, omnivorous, scavenging, thieving, poaching brown rat when it lives near a pond or stream, learns to swim and dive as naturally as a duck. Next comes the vole, or water-rat, which will not live away from water.
This instrument, as part of the original outfit given to the pioneers of the brainy, backboned, and four-limbed races, when they were sent out to multiply and replenish the earth, is surely worth considering well. It consists essentially of a sole, or palm, made up of small bones and of five separate digits, each with several joints.
There were several anatomical differences between the two provinces, but the most conspicuous and most puzzling was the backbone. Nowhere in living nature or in the rocks was any intermediate type known between the backboned and the non-backboned animal. In the course of the nineteenth century, however, several animals of an intermediate type were found.
This period is called the age of invertebrates because, although there is an enormous wealth of animal and plant life in the Silurian, there are no backboned animals except the lowest kinds of fishes. It was supposed for a long time that even fishes were absent. Now we know they existed, but they were small and inconspicuous.
Perhaps the skeletal remains of the vertebrates of the past provide the student of fossils with his best facts, on account of the resistant nature of the bones themselves, and because the backboned animals are relatively modern; then, too, the rocks in which their remains occur have not been so much altered by geological agencies, or buried so deeply under the strata formed later.
There now begins a growth of the septum by which its edges become sharply corrugated, and the suture, or line of juncture of the septum and the shell, is thus angled. VERTEBRATES. It is with the greatest interest that we turn now to study the backboned animals of the Devonian; for they are believed to be the ancestors of the hosts of vertebrates which have since dominated the earth.
The spirally-lined air-vessels run everywhere, and branch out everywhere. The insect, in fact, circulates air instead of blood. As the prick of the finest needle draws blood from the flesh of the backboned creature, it draws air from the flesh of the insect. Who will longer wonder, then, that the insect is so light? It is aerial in its inner nature.
Couch, of Polperro in Cornwall, was equally versed in the true backboned fishes; and to him Edward sent any doubtful midges, or gurnards, or gobies, or whiffs. So numerous are the animals and plants of the sea- shore, even in the north of Scotland alone, that if one were to make a complete list of all Edward's finds it would occupy an entire book almost as large as this volume.
"To what class do the frogs and toads and newts belong? Are they Vertebrate animals? Do they belong to the land or the water?" I said they certainly do belong to the great Backboned family, and are placed in a class by themselves, as they are neither Mammalia, Birds, Fishes, nor Reptiles, properly speaking, and are called Amphibia, because they live, as it were, a double life.
Word Of The Day
Others Looking