632 DR. J. S. BOWERBANR ON THE SPONGIAD.E. [May 7, 



jected beyond the present surface for about half their own length. 

 The network of the skeleton is completely irregular, even imme- 

 diately beneath the inner surface of the crustular dermis ; and, in 

 consequence of the great size of the spicula of which it is composed, 

 the network is large and open. The spicula are all more or less 

 fusiform, and their apices rather bluntly terminated, so much so in 

 some cases as to almost entitle them to be designated as fusiformi- 

 cylindrical. A few large acuate spicula occur intermixed with them. 



The connecting spicula correspond in size with those of the ske- 

 leton ; they are very few in number ; some of them have their large 

 ternate apices so deeply imbedded in the crustular mass as to be 

 nearer to its outer surface than to its inner one ; but the greater 

 number occupy their usual positions, in close adhesion to the inner 

 surface of the crustidar dermis. The component spicula of the 

 ovaria are more than usually delicate in structure, the outer surface 

 of the organ having its reticulations very minute. They are ex- 

 ceedingly abundant in their mature form in the dermal crust ; and 

 in the interstitial membranes beneath they may be found in every 

 imaginable stage of development. When seen sideways they appear 

 somewhat oval in consequence of their being slightly depressed ; but 

 when viewed with the foramen upward, or directly beneath, they 

 present a regular circular form. 



At the first view this species may be readily mistaken for a Geodia ; 

 but a microscopical section at right angles to its surface immediately 

 removes the false impression. 



Hymeniacidon angulata, Bowerbank. (Plate XLIX.) 



Sponge sessile, coating ; surface smooth but very uneven, coria- 

 ceous. Oscula simple, large, and very numerous. Dermis coria- 

 ceous ; dermal membrane spiculous, spicula arranged in more or less 

 flat fan-shaped fasciculi, ovo-spinulate, long and slender. Defensive 

 spicula spinulo-multiangulated cylindrical, very variable in size and 

 form, few in number, very minute. Skeleton densely crowded with 

 spicula ; spicula ovo-spinulate, variable in size and structure. 



Colour in the dried state dark ochreous yellow. 

 Hah. Madeira (Dr. Nathaniel Lister). 

 Examined in the dried state. 



I received eight specimens of this species from Dr. Nathaniel 

 Lister of Madeira, who found them on the rocks at near low-water 

 mark. The largest was 1 2 inches long, by 7g inches greatest breadth, 

 and 2\ inches thick ; the smallest one was A\ by 3| inches, and 

 1| inch in thickness. The whole of them agreed very closely in 

 their external characters. In the dried state their surfaces are very 

 uneven, apparently from the effects of contraction in drying. 



The oscula are exceedingly numerous and very large ; and in one 

 case fully open they measured 8 lines in diameter. In the greater 

 number of the specimens they were mostly closed ; but in one the 

 whole of them were open to their fullest extent, giving to the sponge 

 an appearance closely approximating to that of a mass of irregularly 



