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Show 1867.] DR. BOWERBANK ON HYALONEMA LUSITANICUM. 905 alcyonoid, and oi Antipathes among the sclerobasic zoanthoid polypes." The fact of the general law of increment by means of concentric layers being common to the spicula and fibres of sponges and to the horny axes of the Gorgoniadce, upon which the author lays so much stress, no more proves their relationship to each other than it would to the trees and herbs of the vegetable kingdom, or to the bones of the mammalia; and the reasonings deduced from this aphorism are so inconsequential as to render it quite unnecessary to pursue this portion of the subject any further. The third position assumed by the author is, that " The spicules of sponges are only covered with sarcode ; while the spicules of the Hyalonema are each surrounded by a layer of corium exactly like the inner surface of the bark or corium of the polypes." The law thus attempted to be laid down is essentially incorrect, and could never have been enunciated by any one even moderately acquainted with the anatomy and physiology of the Spongiadce. In all Halichondroid sponges, where the spicula are connected with each other the junctions are formed not by sarcode, but by masses of keratode closely enveloping the adjoining points of the spicula, much after the fashion of a plumber's joint; and in some genera, as in Chalina, the spicula are entirely immersed in the keratose fibres of the sponge, as represented in figures 262 and 263, pl. 13, vol. i. of ' Monograph of the British Spongiadae.' The same structure obtains in the genus DijAodemia, as represented in pl. 14. f. 273, and also in the genera Desmacidon and Raphyrus, represented by figs. 264 and 265, pl. 13, of the same work. The premises attempted to be established by the author thus being proved to be essentially false, it is unnecessary to follow him through the series of reasonings which he has based upon them. The fourth position assumed by the author is, that " The essential character of a sponge is, that it is permeated by canals for the circulation of the water, which is emitted by oscules ; and there is no such structure in Hyalonema." This law, as far as it concerns the structure of a sponge, is correct ; but as regards the assertion that " there is no such structure in Hyalonema," I must leave m y readers who are acquainted with the papers of Professors Brandt and Max Schultze and myself to form their own opinions on the subject. The author's fifth law is, that "The attachment to the sponge appears Tb** be the habit of a single species ; for the Portuguese species, which agrees with the Japanese in most of its essential characters, lives free in the sea, and has the small end of the coral, which in the Japan species is sunk in the sponge, covered with polypes like the rest of the surface." This position, after our knowledge of the acquirement by Prof. Bocage of a specimen of his H. lusitanicum with the basal mass of sponge attached to it, is effectually negatived by the inexorable lo°ic of facts. Dr. Gray, in his paper on " Hyalonema lusitanicum," read January PROC. ZOOL. Soc-1867, No. LVIII. |