402 Mr. J. 8. Bowerbank on the Spongiade, 
lessen the now almost insuperable difficulty that exists under the 
present circumstances, in determining species by description. 
I therefore propose in the first place to limit the genus Spongia 
to such species only as strictly agree in the anatomical structure 
of the skeleton with the two well-known species of the sponge of 
commerce. 
In January 1841* I had the honour of reading before the 
Microscopical Society of London, a paper “On the keratose or 
horny Sponges of commerce,” m which [ have proved the soli- 
dity of the fibre and the occurrence of spicula in certain portions 
of it; but at that time I had not been able to obtain the sight of 
a specimen of either the Mediterranean or West Indian species, 
im the precise condition in which they are, immediately after 
being taken from their native element. Since then I have been 
furnished by my friend Dr. Veronge with specimens of the West 
Indian sponges of commerce, which were undoubtedly alive when 
taken by him from the sea in the harbour at Bermuda, and some 
of which were immediately immersed in spirit to prevent the rapid 
discharge of the gelatinous interstitial matter. 
In addition therefore to my former observations on these ani- 
mals, I may state, that in a living condition the West Indian 
sponge is furnished with a thin, simple, and pellucid investing 
membrane, in which there is imbedded, without any definite ar- 
rangement, numerous simple single-pointed and simple double- 
pointed spicula, among which triradiate spicula are occasionally 
to be seen. 
In one of the specimens obtained by my friend Dr. Veronge 
and preserved in spirit, the interstitial fleshy matter is very abun- 
dant and of a considerable degree of density. It abounds with 
siliceous simple single-pointed, simple double-pointed, triradiate 
and other forms of spicula agreeing precisely in character with 
those I have described in my paper published in the Microsco- 
pical Society’s ‘ Transactions,’ as occurring imbedded in the large 
flattened fibres of the sponge. There is no definite arrangement 
of these bodies, but they appear thickly and irregularly dispersed 
amid the gelatinous matter which fills up the whole of the inter- 
stices of the fibre, excepting those spaces which form the tortuous 
canals of the sponge. 
With this additional information regarding their anatomical 
structure, I propose that the genus Spongia shall be limited to 
those species only which shall strictly agree with the well-known 
and legitimate types of the true Spongie, and that the followmg 
characters be adopted to limit and distmguish the members of the 
genus. 
Gen. Char. Skeleton composed of a network of keratose fibres 
* Transactions of the Microscopical Society, vol. i. p. 32. 
= 
