186".] DR. BOWERBANK ON HYALONEMA LUSITANICUM. 905 



alcjonoid, aud of Antipathes among the sclerobasic zoanthoid po- 

 lypes." 



The fact of the general law of increment by means of concentric 

 layers being common to the spicula and fibres of sponges aud 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 Spon(/iadcB. 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, pi. 13, vol. i. 

 of ' Monograph of the British Spongiadse.' The same structure 

 obtains in the genus Diplodemia, as represented in pi. 14. f. 273, 

 and also in the genera Desmacidon and Raphyrus, represented by 

 figs. 264 and 265, pi. 1 3, 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 circu- 

 lation 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 cor- 

 rect ; but as regards the assertion that " there is no such structure 

 in Hyalonema," I must leave my 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 ap- 

 pears to 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 logic 

 of facts. 



Dr. Gray, in his paper on " Hyalonema lusitanicum," read January 



Proc. Zool. Soc— 1867, No. LVIII. 



