Abstract
THE RATTLE OF THE RATTLESNAKE.—The habit of sloughing is common to all serpents: a short time before the removal of the old skin takes place, the new epiderm makes its appearance beneath the old. The mode of growth of the new and the removal of the old is the same in all snakes, with the exception that, in those with a rattle, that portion of the slough that covers the tip of the tail is retained to form one of the rings of the rattle. The attachment is simply mechanical; the rings are merely the sloughs off the end of the tail. The terminal bone of the tail is formed of vertebrae that have coalesced and changed in great measure their shape; in the different species the number of vertebrae included in this bone varies considerably, and sometimes it varies in individuals of the same species. With the purpose of indicating the manner of growth of the rattle, and as far as possible determining its origin, Mr. S. Carman has followed up its appearance in several species, full details of which, with figures, have been lately published. In the very young rattlesnake, while the vertebrae are still separate, there is no rattle, but about a week after birth a well-marked button is seen; with the first slough the first ring is set free, the button being pushed forward, and a third button is gradually perfected. In time the traces of the vertebrae in the terminal bone are almost obliterated; the bone becomes thickened, pushed forward at its edges, and otherwise enlarged. In a full-grown rattlesnake the hinder seven of the rings belong to the period of the snake's most rapid growth—they form the “tapering rattle” formerly used in classification of the species; while four of the rings and the button are formed while the gain in size was less rapid, and form the “parallelogrammic rattle” of the old classifiers. Many serpents besides those possessed of a “crepitaculum” are addicted to making a rattling noise by vibrations of the end of their tails. In illustration of the extent to which the tail has been modified in different cases, Mr. Carman figures the tails of several species, among others that of Ancistrodon contortrix, Lin., the copperhead of the United States. The tip of its tail is directed downwards as well as a little backwards; most often the button has one or two swellings in a degree resembling those on a ring of the rattle. A living specimen “of this snake” kept for a year or more, would take to rattling on the floor whenever it was irritated; the sound was made by the terminal inch of the tail, this part being swung from side to side in the segment of a circle, so that the tip might strike downward. The result was a tolerable imitation of the sound made by a small rattlesnake.—(Bulletin Museum Comp. Anatomy, vol. xiii. No. 10, August 1888.)
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Biological Notes . Nature 39, 569 (1889). https://doi.org/10.1038/039569a0
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DOI: https://doi.org/10.1038/039569a0