Geology and inhabitants of the ancient world / described by Richard Owen. ; the animals constructed by B.W. Hawkins.

  • Owen, Richard, Sir, 1804-1892.
Date:
1862
Catalogue details

Licence: Public Domain Mark

Credit: Geology and inhabitants of the ancient world / described by Richard Owen. ; the animals constructed by B.W. Hawkins. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    of the Ichthyosaurus being flattened from side to side, that it pos- sessed a tegumentary tail-fin expanded in the vertical direction. The shape of a tin composed of such perishable material is of course conjectural; but from analogies, not necessary here to further enlarge upon, it was probably like, or nearly like, that which the able artist engaged in the restoration of the entire form of the animal has given to it. Thus, in the construction of the principal swimming-organ of the Ichthyosaurus we may trace, as in other parts of its structure, a combination of mammalian (beast-like), saurian (lizard-like), and piscine (fish-like) peculiarities. In its great length and gradual diminution we perceive its saurian charac- ter ; the tegumentary nature of the fin, unsustained by bony fin- rays, bespeaks its afiinity to the same part in the mammalian whales and porpoises; whilst its vertical position makes it closely resemble the tail-fin of the fish. The horizontality of the tail-fin of the whale tribe is essentially connected with their necessities as warm-blooded animals breathing atmospheric air; without this means of displacing a mass of water in the vertical direction, the head of the whale could not be brought with the required rapidity to the surface to respire; but the Ich- thyosaurus, not being warm-blooded, or quick breathers, would not need to bring their head to the surface so frequently, or so rapidly, as the whale; and, moreover, a compensation for the want of hori- zontality of their tail-fin was provided by the addition of a pair of hind-paddles, which are not present in the whale tribe. The vertical fin was a more efiicient organ in the rapid cleaving of the liquid element, when the Ichthyosaurs were in pursuit of their prey, or escaping from an enemy. That the Ichthyosaurs occasionally sought the shores, crawled on the strand, and basked in the sunshine, may be inferred from the bony structure connected with their fore-fins, which does not exist in any porpoise, dolphin, grampus, or whale; and for want of which, chiefly, those warm-blooded, air-breathing, marine animals are so helpless when left high and dry on the sands: the structure in ques- tion in the Ichthyosaur is a strong osseous arch, inverted and span- ning across beneath the chest from one shoulder-joint to the other; and what is most remarkable in the structure of this “ scapular ” arch, as it is called, is, that it closely resembles, in the number.