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Updated: June 25, 2025
Those who lived in the north had discovered the use of copper and had shaped for themselves knives and spear blades out of copper, but not even this metal was in use to any great extent, and for the most part they relied, down to the end of the eighteenth century, for their implements and weapons, on polished and sharpened stones, on deer's antlers, buffalo horns, sticks, sharp shells, beavers' incisor teeth, the claws or spines of crustaceans, flints, and suchlike substances in short, they were leading the same life and using almost exactly the same tools as the long-since-vanished hunter races of Europe of five thousand to one hundred thousand years ago the people who pursued the mammoth, the bison, the Irish "elk", and the other great beasts of prehistoric Europe.
In the course of the evolution of life on this planet there developed from the very simplest forms of animal organisms two different higher forms of life on the one hand the vertebrate animals, possessing an internal skeleton, and on the other hand the insects, clams, crustaceans and other creatures that have their skeletons on the outside, as one may say, in the form of shells.
The gigantic crustaceans called the EURYPTERIDS were also present in this period. The arthropods had now seized upon the land. Centipedes and insects of a low type, the earliest known land animals, have been discovered in strata of this system.
Among the anomalous forms of Old Red fishes not referable to Huxley's Crossopterygii is the Pterichthys, of which five species have been found in the middle division of the Old Red of Scotland. Some writers have compared their shelly covering to that of Crustaceans, with which, however, they have no real affinity.
Newport has described the course of this concentration in insects; and by Rathke it has been traced in crustaceans. In the early stages of the Astacus fluviatilis, or common cray-fish, there is a pair of separate ganglia to each ring. Of the fourteen pairs belonging to the head and thorax, the three pairs in advance of the mouth consolidate into one mass to form the brain, or cephalic ganglion.
Omitting structures whose organic nature has been questioned, there are left to mention a tiny seashell of one of the most lowly types, a DISCINA from the pre- Cambrian rocks of the Colorado Canyon, and from the pre-Cambrian rocks of Montana trails of annelid worms and casts of their burrows in ancient beaches, and fragments of the tests of crustaceans.
When it begins to crack, the crustaceans have to withdraw from out their cuirass the multiple mechanism of their members and appendages, claws, antennae and the great pincers, a slow and dangerous operation in which many perish, lacerated by their own efforts.
For modern investigation and the discoveries made during the progress of natural sciences have shown that in the depths of the ocean, where an everlasting darkness reigns, and where the temperature is extremely low, nevertheless a great abundance of animal life is to be found, and that there exist living beings, not only of the lowest organization, but even fishes and crustaceans of very complicated structure, all of which thrive without enjoying the slightest ray of light.
Canestrini draws the same conclusion from the fact that the males of certain species present two forms, differing from each other in the size and length of their jaws; and this reminds us of the above cases of dimorphic crustaceans. Aug. In this species, as I may add, the male is testaceous and the female black with legs banded with red.
He described to her how newts, during the breeding season, live in the water, subsisting upon tadpoles, insect larvae, and crustaceans; how, later, they make their way to the land and eat slugs and worms; and how the newly born newt has three pairs of long, plumlike, external gills.
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