258 _ Zoological Society :— 
form, such as is represented in fig. 48 of plate 23 of the ‘ Philoso- 
phical Transactions’ for that year. But in the sponge under de- 
scription the shaft is not prolonged through the common base of the 
. triradiating branches, and the second division of these branches is 
much longer than the first or third; the third division, or ultimate 
branchlets, are pointed, and not in the same plane with each other 
or with the preceding portion of the branch, just as in the case of 
the spiculum represented in the figure already referred to. The 
shafts of the spicula project into the reticulations of the skeleton. 
In addition to the large spicula, the dermal membrane abounds with 
minute elongato-stellate spicula having short stout cylindrical radii ; 
and a very few of these are dispersed in the interstitial membranes 
beneath the dermis. On the surface of the skeleton, immediately 
beneath the dermis, there is an abundance of long acuate spicula, dis- 
posed either singly or in fasciculi which are often parallel with each 
other. These acuate spicula are not found in the deeper interstitial 
portions of the sponge, but a few long, very slender, and flexuous 
spicula are occasionally to be found there. No sexradiate spicula 
could be detected, nor were any gemmules observed. 
The single example of this sponge which has been obtained was 
brought up from deep water off the coast of Madeira. It was at- 
tached to a rock or stone by the middle portion of the underside. 
Its colour is white; and although its texture even when fresh was 
firm, the finger-nail easily made a permanent impression upon its 
surface. The animal matter was in comparatively small quantity. 
When a portion of the sponge was immersed in nitric acid it acquired 
a yellow tinge. The shape is that of a concave disk or shallow cup, 
with the border undulated into a few strong folds, some of which 
rise two or three inches above the rest of the surface. In one instance 
the opposite sides of a fold have grown together. The general ap- 
pearance calls to mind a large fungus such as is sometimes seen 
attached to the trunk of an old tree. It measures fourteen inches 
across in one direction, in another twelve inches, and it has a thick- 
ness varying from half an inch to nearly an inch. 
Dr. Gray has had the kindness to let me examine the half of a 
siliceous sponge which came into his possession from Mr. Stutchbury, 
who obtained it, I understand, from Barbadoes, and described it in 
the ‘ Proceedings of the Zoological Society,’ 1841, p. 86, under the 
name of Dactylocalyx pumiceus, in these words :—‘‘ Sponge fixed, 
siliceous; incurrent canals uniform in size; excurrent canals large, 
forming deep sinuosities in the outer surface, radiating from the root 
to the outer circumference.”’ Comparing the sponge now described 
with Dr. Gray’s, I find in mine no well-marked system of incurrent 
and excurrent canals with large orifices, as in the Barbadian sponge, 
which latter is of a much more open and porous texture, and besides 
exhibits in its present state not the slightest trace of a skin. 
Dedicated to Dr. J. 8. Bowerbank, F.R.S., who has devoted his 
attention for many years to the Spongiade, and who is now giving 
to the scientific world, through the medium of the ‘ Philosophical 
Transactions,’ the results of his important investigations. 
