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Show 122 ZOOLOGICAL COLLECTIONS M A D E DURING [Jan. 4, Microciona tuberosa, Bowk. Hymedesmia polita. (Ma- (Straits of Malacca.) gellan.) - c,„ ?/ c • 7 f Spined all over. Length Spined all over. Length o. Small Spmed I ^ .; breadth "0079. 40135 ram.; breadth Acuate. j -006334. 4. Eqaianchorate. Same characters in both. ' Very thinly incrusting ?, Incrusting. Echinating sending out at intervals columns buried in sarcode, echinated columns about with the exception of ter- •34 m m . long. minal spicule-points. "Externally echinated by Smooth, except at points of small spined acuates; sar- projection of skeleton-code dark, not constantly bundles; slightly but con-spicular. stantly spicular. Sarcode Granular, reddish brown. Granular, reddish brown. Habit Dermis This appears to be its nearest described ally; but it is placed with Hymedesmia provisionally (in spite of its wanting the bihamate spicule found in the type, H. zetlandica) in preference to Myxilla and Microciona, owing to its fundamental divergence in spiculation from the type species of those genera. {Note. Any discrepancies between this account of M. tuberosa and that given by Dr. Bowerbank in his description in Proc. Zool. Soc. 1875, p. 281, are justified by an examination of the type specimen. The " somewhat complicated rete," said to be formed by the " skeleton- columns " {I. c.) appears to be not due to the sponge-skeleton, but to an anastomosing mass of tubes formed probably by an arenaceous foraminifer; for the axis of the "columns" is, as a rule, not spicular, but formed of minute grains of sand,) TRACHYTEDANIA l, n. gen. Sponge. Main skeleton composed of vertical inferiorly distinct spiculo-fibres, terminating on surface in radiating brushes ; spicula siliceous, united by a minimum of sarcode, lying parallel in fibre, of three forms, viz. spined acuate, smooth acuate, terminally or sub-terminally inflated cylindrical. Flesh-spicules siliceous, slender, acerate. Sarcode pale-coloured. A basal lamina of spicules may be present. This genus is based on the new species T. spinata. It differs from all the known species of Tedania, Gray, in having three kinds of skeleton-spicules, one of them being spined ; that genus, however, seems to be the nearest genus at present defined. TRACHYTEDANIA SPINATA, sp. n. (Plate X. fig. 10.) Incrusting, laminar. Surface level, glabrous; under lens seen to be minutely but thickly pitted. Colour yellowish white. Vents 1 Pores ? Main skeleton a series of independent, approximately vertical spiculo-fibres, about 3 to 6 spicules thick, rising from a basal lamina of fine cylindrical spicules, and deflected laterally at surface, there breaking up into a horizontal brush of somewhat radiating cylin- 1 From rpaxvs, rough, in allusion to the spined basal spicules, and Tedania, the name of the allied genus. |