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Updated: June 29, 2025
On the other hand, the Crossopterygian Ganoids exhibit the closest connection with Lepidosiren, and thereby with the Amphibia. It should not be forgotten that the development of the Lampreys exhibits curious points of resemblance with that of the Amphibia, which are absent in the Sharks and Rays.
They would take spades and hammers and magnifying glasses and fountain pens, and Oswald's cigar lighter and some lunch, and come back at night with a fine mess of these here trilobites and vertebrae; and ganoids and petrified horseflies, and I don't know what all; mebbe oyster shells, or the footprints of a bird left in solid rock, or the outlines of starfish, or a shrimp that was fifty-two million years old and perfectly useless.
They form a great contrast to the fish of the secondary strata, as, with the exception of the Placoids, they are all Teleosteans, only one genus, Pycnodus, belonging to the order of Ganoids, which form, as before stated, the vast majority of the ichthyolites entombed in the secondary are Mesozoic rocks.
The first vertebrates are sharks, ganoids and garpikes, which are the highest in structure of all known fishes. Darwin's hypothesis demands this order reversed. A painter presented a man with a red canvass, claiming that it represented the children of Israel crossing the Red sea. The question was asked, "Where are the Israelites?" The painter answered, "They have crossed over."
So again, while the group of fishes, termed ganoids, is, at the present time, so distinct from that of the dipnoi, or mudfishes, that they have been reckoned as distinct orders, the Devonian strata present us with forms of which it is impossible to say with certainty whether they are dipnoi or whether they are ganoids.
The Archegosaurus, which we have figured, and the Anthracosaurus, are forms which appear to have existed in great numbers in the swamps and lakes of the age. The fish of the period belong almost entirely to the ancient orders of the ganoids and placoids. Of the ganoids, the great megalichthys Hibberti ranges throughout the whole of the system.
You remember that the fin on the tail of a fish is as a rule bilobed. Now the backbone of a perch or cod ends at a point in the end of the tail opposite the angle between the two lobes, without extending out into either of them. In the shark it extends almost to the end of the upper lobe. Now we have seen that sharks and ganoids are older than cod.
Of the old type of Selachians we have again one lingering representative in our own times to give us the clue to its ancestors, as the Gar-Pike explains the old Ganoids, and the Chambered Nautilus helps us to understand the Chambered Shells of past times.
So far as our present information goes the Ganoids are as old as the Sharks; and it is very interesting to observe that the remains of the oldest Ganoids, Cephalaspis and Pteraspis, have as yet displayed no trace of jaws. It is just possible that they may connect the Monorhina, with the Sturgeons among the Amphirhina.
Then comes the continuation of the description of the Ganoids and the Scomberoids, and an additional sheet contains a sketch of my ichthyological classification. The plates are even more successful than those of the first number. If all goes well the third number will appear next July.
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