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Show 136 MR. c. w. A X D R E W S A N D OTHERS O N T H E [Feb. 20, The skeleton is composed of main lines of multispicular fibre radiating from base to surface, with an irregular reticulum between formed by bundles of one or a few spicules given off from the main lines; the axial columns alone are present in the tufts. The styles, which measure 525 x 12 p, are curved near the basal end. The nearly related species Stylotella polymastia Lendenfeld, referred to by Topsent I. c. p. 466, is synonymous with Hgmenia-cidon fenestration (Ridley). The proper position for the above species appears to be in the Axinellidae. The skeleton is composed of axial lines of monactinal spicules, the reticulation being of secondary importance and absent from the tufts; some of the spicules show a double curve, characteristic of certain typical Axinellid sponges. Distribution. Amboina ; Java ; Christmas Island. MICROCIONA DUBIA, sp. n. (Plate XII. figs. 3,3« ; Plate XIII. figs. 2 a-f.) Sponge forming an almost free or loosely incrusting lamina with margins curled up, with foreign particles adherent to the under surface where the latter is free. Colour yellow; upper surface smooth. Skeleton formed partly of columns, each composed of one stout subtylote spicule, aud partly of plumose columns of more slender tylotes opening out from base to surface, where they almost form a distinct dermal layer ; numerous short spined styli arranged vertically with bases on the basal layer of the sponge. Spongin absent. Spicules. Megascleres-stout, slightly curved subtylotes 324 x 7*5/i, head 7*7 p, slightly spined, occasionally facetted. Slender straight tylotes 318-328ju x5-5 p, head 7 p with basal end spinous. Short spined styli 48 x 7*5 p, with sharp, often curved, spines on the basal three-fourths of the length of the spicule. Microscleres-palmate isochelae from 3 to 12 p. Toxa large, slender, 39 x 1 p ; a shorter but thicker form (numerous), 6 x 1*5 p. The size of the specimen is 2*5 c.c. x 5 c.c. in area, and 1 m m. in thickness. The unispiculate columns, which occur in parts of the sponge, recall the chief character of Hgmerrhaphia. Again, the spiculation closely resembles that of certain species of Rhaphi-dophlus (R. filifer Ridley & Dendy and R. spiiculosus Dendy), but the absence of spongin excludes the new species from this genus. The specimen is probably mature, since there are several embryos near the base of the sponge. IOTROCHOTA BACULIFERA Ridley, var. TUMESCENS, var. nov. (Plate XIII. fig. 1.) Specimen forming an irregular flabellate and branching growth, 6 c.c. X 1 c.c. in area and -3 c.c. in thickness. Spicules. Styles averaging 210x10//. Strongyles 220-250 xl p, with from one to three fusiform |