398 Dr. Bowerbank on Hyalonema mirabills, 



another) between the sponge and the coral." But, if this theory 

 of Dr. Gray's be correct, the " mutual understanding" must have 

 been carried very much further than the Doctor supposes — even 

 to the extent of sharing the spicula of their respective skeletons 

 between them, as the remarkable cylindro-cruciform siliceous 

 spicula, so abundant in the inner coat of the envelope of the 

 siliceous rope of spicula, are still more so in the body of the 

 basal sponge. This uniformity in their anatomical structure, to 

 an unprejudiced naturalist, would seem rather to identify them 

 as parts of the same animal than of two distinct species, how- 

 ever closely attached by ties of " mutual understanding." But 

 the truth appears to me to be, that, although Dr. Gray has had 

 the British Museum specimen with the spongeous base under his 

 care for many years, he has never yet made a careful micro- 

 scopical examination of the tissues of its basal mass. 



In page 291 he writes, " In 1860 Professor Max Schultze 

 published the elaborate essay above quoted ; and he regards 

 the rope of siliceous spicula as part of a sponge, and the 

 polypes as parasitic on it, calling the polypes Polythoa fatua 

 mihij" and he continues, "Dr. Bowerbank, adopting the same 

 view, in his lately published work on British Sponges, gives the 

 following as the generic character of the genus Hyalonema." 

 This asertion is incorrect, as I have always maintained that the 

 siliceous axis, its envelopment, and the basal sponge were all 

 parts of the same animal, as the following generic characters I 

 have proposed will prove. 



Hyalonema, Gray. 



" Skeleton an indefinite network of siliceous spicula, composed 

 of separated elongated fasciculi, reposing on continuous mem- 

 branes, having the middle of the sponge perforated vertically by 

 an extended fasciculus of single, elongated, and very large spi- 

 cula forming the axial skeleton of a columnal cloacal system " 

 (vol. i. p. 196). 



I will not at present follow the author of the paper through 

 all his reasonings on the subject, as mere opinion or mere 

 argument form by no means the best mode of settling such 

 disputes, and as I shall shortly publish a full detail of my 

 examinations of the anatomy and physiology of Hyalonema, in 

 which, I trust, I shall be able to prove that the basal sponge, the 

 spiral axis, and its coriaceous envelope are really parts of one and 

 the same animal. There is another misrepresentation which I 

 cannot allow myself to pass without comment. Dr. Gray, in 

 page 292, writes, " Unfortunately Dr.Bowerbank does not seem 

 to have considered it necessary to examine the specimens, but 

 simply copies the plate^ or to examine other genera of corals ; or 



