Dysidea, , Johnston.

Gen. DYSIDEA, Johnston. View in CoL

Char, emend. Fibrous arenaceous sponges, in which the fibre is chiefly composed of foreign microscopic objects (sand, fragmentary sponge-spicules, &c.), held together by a mere film of keratine, supporting the flakes of the parenchymatous sarcode; traversed by the branches of the excretory canal ­ system; assuming a variety of sponge-like forms, on which the pore-dermis may be continuous and smooth, or rendered more or less uneven and rough by projection of the subjacent fibre, according to the species.