OCR Text |
Show 1867.] DR. J. E. GRAY ON SPONGES. 503 Fam. 2. APHROCALLISTIDLE. Sponge tubular; tubes reticulate, sub-circular, closed at the end with a netted lid. Order II. KERATOSPONGIA. Sponge elastic. Skeleton formed of horny netted fibres, generally -without, but sometimes more or less strengthened with, minute siliceous spicules or grains of sand. Fam. 3. SPONGIADCE. Skeleton formed of one kind of reticulated horny fibres, not enclosing any spicules or sand. Fam. 4. HIRCINIAD^E. Skeleton formed of two kinds of horny fibres :-the one, forming the base of the skeleton, thick, reticulated, with a more or less distinct central line of minute spicules or grains of sand; the other very slender, at the apex of the branches, which do not anastomose. Fam. 5. DYSIDEID^E. Skeleton formed of reticulated horny fibres with sand or spicules of other sponges imbedded in the centre, and covered with a more or less tbick coat of horny matter. Brittle when dry. Fam. 6. CHALINID.E. Skeleton formed of reticulated horny anastomosing filaments, which have one or more series of siliceous spicules in the central line. Fam. 7. OPHISTOSPONGIAD.E. Skeleton netted horny, or expanded skin-like fibres, covered with superficial spicules, forming an irregular coat, or which are single or grouped, and divergent from the surface. Fam. 8. P H A K E L L I A D J G . Skeleton formed of closely reticulated horny fibres, forming an expanded mass; spicules numerous, in bundles, forming radiating, repeatedly branched lines, which do not anastomose on the surface. Subsection 2. Spicular Sponges (SPICULOSPONGI,E). Sponge fleshy, more or less strengthened by fasciculated or scattered siliceous spicules, the bundle being sometimes slightly covered with a thin layer of horny matter. Hie sarcode is generally abundant; in some few, as Euplectella, it is thin, mucilaginous, and deciduous. Order III. LEIOSPONGIA. Sponge-spicules only of one kind, often varying in size and shape in the same species. Fam. 9. HALICHONDRIADCE. Skeleton composed of fusiform or pin-shaped spicules variously fasciculated together, or rarely united by a small quantity of horny matter. Sarcode granular or fleshy. Fam. 10. POLYMASTIAD^E. Sponge with tubular fistulous branches; tubes open at the end, and formed of longitudinal and transverse fascicules of fibres. |