sponges from the Atlantic Ocean. 463 



The peculiarity of the staple spicule of the interior is that it 

 presents four smootli, round arms, which, radiating irregularly 

 from a central point, soon divide into two branches respectively 

 that terminate botryoidally or in the form of a bunch of 

 grapes, which unites or interlocks with that of the neigh- 

 bouring branch ; and thus the internal structure is formed, 

 except at the surface, where the branches immediately under 

 the dermal layer of disks &c. terminate respectively in flat 

 filigreed or dendriform expansions which do not intermingle 

 with those of opposite branches. In tlie dermal disks there is 

 a circular space opposite the end of the shaft with a trijid 

 line, which represents the trifid central canal ; and this in the 

 body of the spicule of the interior is often seen in its quadruple 

 forni^ from the addition of the shaft, which makes tlie fourth 

 arm. Colour yellowish grey or white. Here, again, I prefer 

 the term ^^ Discodermia^'' of Bocage to that of '"'' Dactylocalyx^'' 

 Bowerbank, for the reasons above mentioned. 



Several fragments of this sponge were dredged up on board 

 the ' Porcupine,' probably near Cape St. Vincent ; but they 

 are all dry and without number. Unlike the foregoing, they 

 are all more or less rounded and elliptical, varying in size, 

 under I inch long by ^ of an inch in their short diameter. 

 One fragment is a little longer and somewhat lobed ; but they 

 give no idea whatever of what the general form of the entire 

 sponge might have been. Like the fragments of the foregoing 

 species, too, they are sarcodeless, and partly filled with deep- 

 sea mud and its accompanying minute organisms, but not 

 overgrown with other sponges, perhaps from their having been 

 less stationary and more exposed to friction than the fragments 

 of Corallistes BowerhanMi ^ except in one instance, where the 

 rolled fragment presents a depression in which there is a good 

 specimen of Opkiraphidites tortuosus. 



The peculiar form of their internal structure, and the presence 

 of the peculiar dermal disks amongst it in considerable num- 

 bers, although no trace of the flesh-spicule remains, are quite 

 sufficient to establish the species. 



For good illustrations of the dermal and flesh-spicules, 

 together with that of the staple spicule of the interior, 

 see Dr. Bowerbank's figures ^(Proc. Zool. Soc. 1869, pi. vi. 

 figs. 9-14) and Bocage's " Eponges siliceuses nouvelles de 

 Portugal et de I'ile St. lago, Archipel de Cap-Vert" (Journal 

 des Sci. Mathemat., Phys. et Naturelles, no. iv. Lisbonne, 

 1869). 



It may seem strange that only dead fragments of this and 

 the foregoing Corallistes were dredged up on board the ' Por- 

 cupine ;' but when it is remembered that these sponges grow 



