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Show 138 MR. C. W. ANDREWS AND OTHERS ON THE [Feb. 20, Skeleton consisting of slender vertical main lines, loosely joined by single spicules in horizontal plane excepting near the surface, where the main fibres are isolated. Spicules. Styles 132 xlfi, with a sharp bend at the centre. Oxea 1 4 4 X 4 J U , sharply curved at the centre, and gradually diminishing to sharp points. The skeleton is like that of a Petrosia, but very loosely arranged. The specimen is too fragmentary to serve as the type of a new species. RHIZOCHALINA PELLUCIDA Ridley. 1884. Rhizochcdina pellucida Ridley (11. p. 608, pi. liv. fig. j). There are only three small fragments of fistules, the longest being 4 m m . in length and 1*5 m m . in diameter. The spicules are slightly smaller than in the type specimen, being 240 x 9 p in the former, and 260 x 10 p in the latter, but the shape is the same. Distribution. Providence Island, Mascarene Group; Christmas Island. RHIZOCHALINA SESSILIS, sp. n. (Plate XII. fig. 5 ; Plate XIII. fig. 8.) Sponge pyramidal or digitate, sessile, arising from an incrusting base; surface smooth; consistence firm but rather brittle ; colour (in formol) white-crystalline ; translucent. Skeleton consisting of an axial or central open spiculo-fibrous network formed of broad loose strands about 10 spicules thick, surrounded by a cortical network of more slender strands at right angles to the central network, and of a dermal isodictyal network with strands 2-3 spicules thick, with unispiculate strands in the interstices. Spicules. Oxea 372 > 14/.<, curved at the centre and diminishing suddenly near the ends to sharp points. Micioscleres 0. There are several specimens and fragments, most of them being of flattened digitate form, the largest being 30 mm. in height, 8 m m . in breadth, and 3 m m . in thickness. The specimens preserved in alcohol are dark yellow at the surface, and bright yellow in the interior, the formol specimens being white. The new species is very near Pellina eusiphonia Ridley (11. p. 414, pi. xii. fig. x), from Port Darwin, but differs in the shape of the sponge and in the size of the spicules. These two species come within the subfamily Phlceodyctiinae rather than within the Renierinae. RENIERA INNOMINATA, sp. n. (Plate XII. figs. 6, 6 a ; Plate XIII. figs. 5 a-b.) Sponge incrusting ; colour pale brown with a faint reddish tinge ; texture soft and elastic. Skeleton forming a rather regular reticulum of unispiculate fibres with triangular (mostly) and quadrangular meshes with nodes cemented with spongin. |