and Acapulco Sponges. 275 



therses " — since it is exceedingly plentiful in the West-Indian 

 seas, growing in some parts where the water is hardly a metre 

 dee]) (de F. et M., " Revue," p. 37), and yet 1 found a specimen 

 equally affected by it which was dredged near Cape St. 

 Vincent on board H.M.S ' Porcupine' in 374 fathoms. Al- 

 though, in most instances, the whole of the sarcode is 

 destroyed, still in many this is only partially the case, while, 

 of course, there are also many instances wherein there is no 

 trace of the filament at all to be seen, and tlie Hircinia re- 

 mains so far intact. Lastly, the transformation goes on so 

 gently and yet so completely that the delicate white lace- 

 like reticulation which is often seen in the dermal sarcode 

 tympanizing the polygonal divisions between the projecting 

 points of the fibrous structure on the surface of the Hircinia 

 is frequently left when every particle of sarcode that was 

 in contact with it has. disappeared, thus remaining on a 

 tympanizing membrane formed by the filaments instead of 

 the sarcode. This lace-like reticulation arises from the deli- 

 cate fibro-reticulation in the dermal sarcode, before mentioned, 

 attaching to itself microscopic objects of all kinds, which 

 sometimes goes on to such an extent as to produce a con- 

 tinuous incrustation, in which case, of course, the reticulated 

 structure becomes obscured. 



Group 16. Aeenosa. 

 Dysidea tuhulosa, n. sp. 



Tubes erect, groiiped in juxtaposition ; fragile. Colour 

 white, chiefly from being densely charged with a small white, 

 filiform, branched coralline (Jania). Tubes 1^ inch high and 

 ^ inch in diameter when dry. 



Hab. Marine. 



Log. Nassau. 



Obs. This, in description and figure, corresponds with de F. 

 et M.'s Terpios jania (p. 101, pi. xxii. figs. 8, 9), in which 

 the spicules are said to be " aciniformes," whatever this may 

 mean ; but it is not the case, in particular, with our specimen, 

 Avhere the variety of difterent forms of fragmentary sponge- 

 spicules and other foreign bodies at once testifies to its nature j 

 hence the name above given. As we cannot assume that the 

 Jania^ when growing by itself, has this tubular form, so we 

 cannot assume that it belongs to the Dysidea alone ; hence 

 it may be produced by the two growing together jyari jjassn ; 

 although another instance of this kind Avas dredged in the 

 harbour of Acapulco by Capt. AV. H. Cawne W^arren, in 

 which the sponge is Renicra Jibulata^ Sdt., in combination 



