Antedon

Abstract: In the year 1827 Mr. J. V. Thomson, Deputy Inspector-General of Military Hospitals, described and figured what he believed to be a new recent Crinoid, under the name of Pentacrinus Europœus; and in June 1835 communicated to this Society a “Memoir on the Star-fish of the genus Comatula, demonstrative of the Pentacrinus Europœus being the young of our indigenous species.” In this memoir the author describes and figures a series of Pentacrinus Europœus from its earliest stage, in which it is represented as “an attached ovum in the form of a flattened oval disk, by which it is permanently fixed to the point selected, giving exit to an obscurely jointed stem ending in a club-shaped head”; to its most perfect attached condition, in which the head is compared with, and found closely to resemble the youngest free Antedon taken with the dredge. The period of the disappearance of the pentacrinoid larvæ on the oar-weed exactly corresponds with that of the appearance of the most minute free Antedons in the water. Mr. Thomson’s observations were conclusive. I am not aware that they have hitherto been repeated in detail on the European species, but the “pentacrinoid ” stage of Antedon has ever since been the frequent and familiar prize of the dredger, the wonderful beauty and gracefulness of its form and movements, and its singular relations to the Echinoderm inhabitants of modern and of primæval seas, rendering it an object of ever recurring admiration and interest.

Abstract: That the only secure basis of Zoological Science is afforded by a thorough elucidation of the structure and life-history of typical forms representing particular subdivisions of the Animal Kingdom, will not, I anticipate, be disputed by any Naturalist of the present day. And every one who is even slightly acquainted with the history of that Science must be well aware that the standard Monographs which have been devoted to this object have exerted a more permanent influence on its progress, than have any of those comprehensive Systems which have been set up from time to time, and, after lasting for a while, have been overthrown to make way for others scarcely more durable. For any System of Classification is liable to be invalidated by new discovery; and the utmost which can be claimed for it is, that it accurately represents the state of knowledge at the time of its promulgation. But every Monograph which contains a faithful description of the structure and life-history of any type whatever, however far it may be from absolute completeness, presents a body of facts which subsequent research may add to but cannot set aside; and may come to acquire, even at a long subsequent period, a value not anticipated by its author. I cannot suppose, therefore, that any apology is needed for my offering to the Royal Society a detailed account of perhaps the most interesting of our British Echinoderms; of which the structure, notwithstanding the attention given to it by various eminent Anatomists, has been hitherto but very imperfectly made out; whilst of its life-history still less is known. That I have solved every problem which its study has presented, is far more than I can afiirm; but I venture to think that what I now bring forward Will stand the test of future scrutiny; and that the results I have attained will prove of importance, not merely in leading to a better understanding of the important group of which Antedon is a representative, but also in helping to the solution of certain fundamental questions in General Physiology.