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Show 324 DR. J. S. BOWERBANK ON SILICEO-FIBROUS SPONGES. [May 13, IPHITEON PANICEA, Valenciennes. Sponge cyathiform, slightly pedicelled. Surface of rigid skeleton even ? Oscula, pores, and dermal membrane unknown. Skeleton symmetrically radial; radii short and stout; areas of the rete mostlv six-sided, spaces within triangular; fibre cylindrical, incipiently spinous. Tension-spicula simple, hexradiate, slender, abundantly spinous; radii terminally more or less clavate. Retentive spicula spinulo-pentafurcated? hexradiate stellate, few in number. Gemmules simple, membranous, subspherical, irregularly dispersed, very numerous. Colour in the living state unknown. Hab. Porto Rico, 1/99 (Prof. Valenciennes). Examined in the state of skeleton. The specimen designated Iphiteon panicea in the Museum of the Jardin des Plantes, Paris, is said to have been brought from Porto Rico in the year 1/99. It is an irregularly cup-shaped sponge, the diameter of its distal margin being about equal to its height, which, to the best of m y recollection, was from 7 to 8 inches. From the colour and general appearance of the specimen, I believe it to be the one from which Prof. Valenciennes gave a small fragment to Prof. Melville some years since, which he kindly transferred to me, and which fragment contains the gemmules in situ. I have so fully described the general structure of the skeleton in m y description of the genus, as to render it unnecessary to dilate further on that portion of its history. No fragments of the expansile dermal system could be detected; and we are therefore deprived of the most important specific characters. I could not detect auxiliary skeleton-spicula, simulating hexradiate spicula, springing from the primary skeleton-fibres and anastomosing freely with each other, as in Dactylocalyx; but in lieu of them true simple hexradiate tension-spicula were frequently to be seen in groups in the interstitial spaces, but they never appeared to inosculate with each other or to deviate from their normal forms. These spicula are of comparatively large size; the radii are slightly and progressively attenuated, and entirely and acutely spinous, but they do not terminate in a point, but either in a group of acute spines or they are more or less subclavate. The retentive spicula appear to be exceedingly few in number in the interstitial tissues; iu several small masses of the skeleton abounding in sarcode and gemmules I found but two of them. The secondary radii were apparently five in number, but they were so much obscured by the surrounding sarcode as to render the determination of this character very uncertain. The simple membranous subspherical gemmules are very like those of a halichondroid sponge; they are very numerous, somewhat variable in size and form, and are nearly all of them attached to the skeleton-fibres. A portion of the skeleton with the gemmules is figured hi the |
