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Show 354 DR. BOWERBANK ON ALCYONCELLUM SPECIOSUM. [Mar. 28, I might make a searching investigation of the peculiarities of its structure. Dr. A . Farre also allowed m e the free examination of his specimen, described and figured in the ' Transactions of the Linnean Society of London,' vol. xxii. p. 117, pl. 21, as Euplectella cucumer, Owen. I have repeated these investigations on two other specimens in m y possession, of nearly the same size and form as that formerly possessed by M r . Cuming, but now in the British Museum ; and I have found that the structure of their skeletons and the curious and beautiful forms of spicula contained in their interstices are perfectly identical even to the minutest form ; so that we m a y reasonably and safely conclude that there is but one species of this beautiful sponge known to us at present in England, and that it is identical with the species described by M M . Quoy and Gaimard in their ' Zoology of the Voyage of the Astrolabe.' Neither of the above-named authors, nor Prof. O w e n in either of his descriptions of the sponge, has given us a detailed statement of its specific characters ; I shall therefore proceed to endeavour to rectify this omission as follows:- ALCYONCELLUM SPECIOSUM, Quoy et Gaimard. Sponge sessile, cylindrical, more or less curved, enlarging progressively from the basal to the distal extremity; upper portion furnished with numerous sharp ridges of interlacing fibres disposed diagonally and somewhat symmetrically; apex truncate, closed by a coarse, ventricose, fibrous network, and encircled by a strongly produced fibrous ridge or frill. Base furnished with numerous fasciculi of large and long prehensile spicula projected downward • spicula attenuato-quaternate, barbed alternately for about one-third of their length from the distal extremity. Oscula congregated, terminal. Pores congregated; inhalant apertures symmetrically equidistant, disposed in lines radiating from the base to the apex of the sponge. Dermal membrane unknown. Skeleton symmetrical; primary lines radiating from the base to the apex, equidistant; secondary lines at right angles to the primary ones ; interstitial structures interlacing diagonally. Spicula of the membranes :-interstitial spicula rectangulated, attenuated hexradiate spicula, short and stout, rarely completely developed; and the same form with slender and delicate radii, fully developed; also attenuated rectangulated triradiate, api-cally spined. Spicula of the sarcode :-trifurcated attenuato-hexra-diate ; and floricomo-hexradiate, very minute. Colour, skeleton very light amber-yellow. Hab. Philippine Islands, Island of Bohol, 10 fathoms (Mr. LLugh Cuming) ; Island of Zebu, about 24 fathoms (Mr. R. Geale). Examined in the skeleton state. The form of the skeleton of the sponge is exceedingly graceful; it is that of an elongated Cornucopia, composed of a beautiful and regular network of siliceous fibres. It has no solid base to retain it in an erect position; but in lieu of this support it is furnished with a vast number of curious and beautiful retentive spicula, each acting the part of a line and grapnel when their recurvo-quatemate heads |