398 -Dr. Bowerbank on Hyalonema mirabilis, 
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 
mihi;” 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. 
Hyatonema, 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 
