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Show 298 DR. j. s. BOWERBANK ON THE SPONGIAD^E. [May 5, 7. Contributions to a General History of the Spongiada. By J. S. BOWERBANK, LL.D., F.R.S., &c-Part VI. [Received April 4, 1874.] (Plates XLVI. & XLVII.) GEODIA CARINATA, Bowerbank. (Plate XLVI. figs. 1-5.) Sponge sessile, coating stems of Gorgonia or Fuci. Surface smooth, but furnished with numerous longitudinal carinae. Oscula simple, dispersed, few in number. Pores inconspicuous. Dermal membrane thin and pellucid, furnished abundantly with multiangu-lated cylindrical spicula. Skeleton-fasciculi multispiculous, compact ; spicula attenuato-spinulate, bases coincident. Interstitial membranes furnished abundantly with arborescent elongo-subsphero-stellate retentive spicula, variable in degree of development. Ovaria oval or kidney-shaped, component spicula slender and delicate. Surface-rete very minute. Colour in the dried state light fawn-yellow. Hab. South Sea (Mr. Thos. Ingall). Examined in the dried state. I received the figured specimen of this singular species from my late friend Mr. Thos. Ingall in 1854, and 1 then described and named it in M S . ; and subsequently the multiangulated cylindrical spicula of the dermis were described and figured in m y paper on the " Anatomy and Physiology of the Spongiada," in the Philosophical Transactions of the Royal Society for 1858, p. 314, plate xxvi. fig. 10, and also the arborescent elongo-subsphero-stellate retentive spicula of the interstitial membranes in p. 308, plate xxv. fig. 19 of the same part for 1858. Shortly after I had examined and named the species I saw a similar specimen in the British Museum arranged among the Corals ; and I stated to Dr. Baird that it was a sponge and told him the name I had assigned to it, and he forthwith removed it from the case and placed it among the Sponges. Subsequently I obtained a second specimen by purchase in the year 1864. The whole three specimens were similarly parasitical and very closely resembled each other in their external characters, and especially so in their singularly carinated striation. O n taking sections at right angles to the surface of the sponge, I found that these elevated ridges were produced by the projection of lines of skeleton-fasciculi through the dermal crust of the sponge to immediately beneath the dermal membrane, but in no instance did thev appear to perforate that organ. The greater portion of these carinated elevations were in a longitudinal direction ; but occasionally short transverse ridges are found connecting the longitudinal ones with each other. The dermal membrane is thin and pellucid, and when in a fine state of preservation it is literally crowded with innumerable minute |