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Updated: September 17, 2025
Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is some truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification.
It is said truly that the Ammonite, Orthoceras, and Nautilus of these ancient rocks were of the tetrabranchiate division, and none of them so highly organised as the Belemnite and other dibranchiate cephalopods which afterwards appeared, and some of which now flourish in our seas. Therefore, we may infer that the simplest forms of the Cephalopoda took precedence of the more complex in time.
The great oyster family dates from here. Cephalopods are now to have their day. The archaic Orthoceras lingers on into the Triassic and becomes extinct, but a remarkable development is now at hand for the more highly organized descendants of this ancient line. We have noticed that in the Devonian the sutures of some of the chambered shells become angled, evolving the Goniatite type.
In the Silurian ages, invertebrates brachiopods and crinoids and cephalopods were the dominant types. But very early no one knows just when there came fishes of many strange forms, some of the early ones enclosed in turtle-like shells.
He paused a moment, as if in deference to my inability to follow him on such an abstruse topic, then resumed, "As far as I am able to determine, this poison or toxin is an amin similar to that secreted by certain cephalopods found in the neighborhood of Naples. It is an aromatic amin. Smell it." I bent over and inhaled the peculiar odor.
That fantastic extension of the Cephalopods to cover the Pteropods ... But I wander from Hapley and Pawkins. It was war to the knife. However, it would scarcely interest the reader to detail how these two great men quarrelled, and how the split between them widened until from the Microlepidoptera they were at war upon every open question in entomology. There were memorable occasions.
Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is some truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification.
The day of the ammonite and the belemnite also now drew to a close, and only a few of these cephalopods were left to survive the period. It is therefore at the close of the Cretaceous that the line is drawn which marks the end of the Middle Age of geology and the beginning of the Cenozoic era, the era of modern life, the Age of Mammals.
Let us first glance at the advances among the inhabitants of the seas. The most important and stimulating event in the seas is the arrival of the Ammonite. One branch of the early shell-fish, it will be remembered, retained the head of its naked ancestor, and lived at the open mouth of its shell, thus giving birth to the Cephalopods.
CEPHALOPODS. Among the mollusks we must note the evolution of the cephalopods. The primitive straight Orthoceras has now become abundant. The nautilus, which began its course in this period, crawls on the bottom of our present seas.
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