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Show 1868.] DR. J. E. GRAY ON XYLOSPONGIA COOKII. 637 4. Note on Xylospongia cookii, a New Genus of Palmated Sponges in the collection of the British Museum By Dr. J. E. G R A Y , F.R.S., V.P.Z.S., &e. In the British Museum is a very extraordinary, lobed, woody, palmated body, with eight flattened, irregularly netted, strap-like lobes. It has been in the collection for many years, but has not been named ; indeed grave doubts have been entertained if it were not the woody skeleton of some vegetable production. Being without any habitat, it has been left unnoticed, in hopes that a second specimen might occur accompanied by some details of its history. It was doubtless collected on the sea-coast, as one of its sides is more or less covered with the undervalves of some very young oysters and other attached marine shells. Being desirous of knowing more of its structure, I submitted a small fragment of it to the examination of Mr. M. C. Cooke of the India Museum, who informs me there can be no doubt of its being a sponge belonging to my family Halichondriadee, the substance of it being studded with abundance of smooth, slender, fusiform, slightly curved siliceous spicules. I have named the species after Mr. Cooke. XYLOSPONGIA (Fam. HALICHONDRIADEE). Frond compressed, fan-shaped, divided above into strap-shaped flat lobes, rather wider at the ends. Root an expanded disk. Stem thick, woody, subcylindrical below, compressed above and expanded into a flat fan-like frond, which is divided above into eight or ten strap-like flat lobes, like the fingers on the hand, the lobes varying rather in width, the outer one on each side being the narrowest. The root and stem are solid, wood-like ; the upper part of the broad expanded, fan-like part of the stem more or less pierced with different- sized perforations, and the part divided into strap-like reticulate lobes, which are generally rather wider at the ends. The expanded part of the stem and the strap-like lobes are all formed of parallel cylindrical filaments, about as thick as twine, which in the upper part of the stem are united together by woody matter, leaving only a few perforations between them ; but in the strap-like lobes the filaments are much more distinct, rather flexuous, inosculating where they meet their neighbouring subparallel filaments, united by the woody material, which is not quite so thick as the filaments. The surface is rather rugose, the minute rugosities of the stem and filaments being placed longitudinally and parallel to each other. Spicules of one kind, minute, slender, fusiform, often very slightly curved or arched. XYLOSPONGIA COOKEI. Hab. • |