346 DR.J.S. BOWERBANK ON SILICEO-FIBROUS SPONGES. [ May 13, 
skeleton in nitric acid, when it will be immediately apparent that no 
disintegration of the reticulated structure results from this operation, 
which would inevitably be the case if it were formed of fasciculi of 
spicula held together by sarcode only. On the contrary, the whole 
of the skeleton is formed of an irregular network of solid siliceous 
fibres approaching each other and anastomosing with more than the 
usual frequency in such sponges. 
Very few, if any, of the secondary fibres in either the transverse 
or diagonal portions of the skeleton are simple in their structure. 
-They seem always to be composed of two or more simple fibres 
running parallel to each other and anastomosing at short distances. 
Sometimes the anastomosing points of two parallel fibres are so close 
to each other that the two thus combined have the appearance of a 
narrow tape or ribbon with thickened margins and a line of nearly 
uniform pinhole perforations running down the middle of it. 
Amidst these complicated anastomosing lines of the skeleton nu- 
merous stout rectangulated hexradiate and triradiate spicula are irre- 
gularly mixed; they appear as if they were simply entangled amidst 
the tissues supporting and supported by the interstitial membranes 
of the sponge. None of them under these circumstances have any 
permanent connexion with the skeleton; neither do the spicula of 
the numerous bundles of long prehensile organs so abundant towards 
the base of the sponge ever anastomose with the skeleton-fibres or 
with each other. No marks of such an attachment can be detected 
upon any part of them ; and, in truth, their recurved spinous appen- 
dages and their long and flexible shafts imbedded in the tough mem- 
branous integuments of the dermal tissues renders such anastomsis 
of the organs with the rigid skeleton quite unnecessary ; and if we 
measure the probability of the possession of such dermal integu- 
ments by Alcyoncellum in a living state with what we know of the 
dermal structures of Dactylocalyx Masoni, Prattii, &c., little doubt 
can remain in our minds that its dermal integuments are much 
of the same nature as those of the rest of the rigid siliceo-fibrous 
sponges. The structure of the stout network of the oscular area is very 
similar to that of the corresponding organ in Iphiteon beatrix. Kach 
fibre of the net is compounded of a condensed mass of simple skeleton- 
fibres anastomosing in every direction as in that of I. beatriz. In 
truth, the more searchingly we examine the skeleton-structures of 
the beautiful subject under description the more closely we find its 
alliances to be to the great family of the siliceo-fibrous sponges. 
It is much to be regretted that, amidst the large number of speci- 
mens that have recently been imported, there does not appear to 
have been any one of them preserved in the living state as when 
taken from the sea; nor have we any well authenticated report by 
a competent naturalist of their condition when thus obtained. But 
if we may reason from the analogies presented by other siliceo-fibrous 
sponges preserved in the state in which they were taken from the 
sea, we should expect to find Alcyoncellum with a stout and some- 
what coriaceous enveloping dermal membrane; and I have in my 
possession a fragment of such a membrane about 2 lines in length, 
