Dysidea

Hab. Marine.

Massive, sessile, more or less contracted towards the base, simple or lobate; lobes convex, mamilliiorm, digital, sub ­ branched or indefinitely varied in their forms. Consistence firm, but easily broken, light. Colour grey externally, generally orange-yellow internally. tSuriace smooth and even or more or less rough, consisting of the dermal membrane, raised or not into small conuli by the projection of the subjacent aienaceous fibre. Pores in juxtaposition, uniformly continued over the dermal membrane, or interrupted in their continuity by the projections of the subdermal fibre. Vents numerous and large, sitm ted on the prominent parts, at the ends of the mamilliform lobes, or along the borders or ridges of the crested growths. [Structure fibro-reticulate: fibre arenaceous, tympanized in its interstices by the parenchymal sarcode traversed by the branches of the excretory canal-systems. Size variable.

Obs. When fresh this sponge, although firm, is easily broken, on account of the minimum of keratine which holds together the arenaceous material of the fibre. 1 have as ­ sumed that it is the species alluded to by Dr. Bowerbank, because out of a great number of specimens in Mr. W ’ ilson ’ s collection, as well as in the British Museum, 1 can find no other meriting the term “ Dysidea, and Dr. Bowerbank docs not appear to have gone beyond the description of its fibre, while it is certain that it was among the Australian sponges which Air. Kirk sent to him about the end of 1840 (Trans. Microscop. Soc. Loud. vol. i. p. 32).

Loc. Port Phillip Heads, South Australia. Depth variable.