Report on the zoological collections made in the Indo-Pacific Ocean ...

;614 COLLECTIONS FROM THZE WESTERN INDIAN OCEAN.Clathrias, except perhaps C. elegans, Vosmaer (habit unknown), andC. (DlcU/ocylindrus) anchorata, Carter. The latter is only knownfrom small shapeless masses, and has the skeleton-spicule stout,smooth, and strongly curved; otherwise the spicular complementis essentially the same. In the present species the two kinds ofanchorates appear to be distinct, the smaller form being veryabundant, the larger, though evidently normally present, much lesscommon ;the occurrence of a larger and smaller anchorate in someEsperice, as pointed out by Carter (Ann. & Mag. N. H. 1882, ix.pp. 298, 299), is an analogous circumstance.36. Clathria mseandrina. (Plate LIU. fig. I ; Plate LIV.figs. 7i-h".)Sponge only known as an incrusting, widely-spreading mass,consisting of a thin basal lamina not exceeding 1 millim. in thickness,from which arise vertically, at intervals of 1 to 3 millim., parallel- walledridges, or triangular masses, about "5 to 1'5 millim. in diameter and2—1 miUim. in height, usually united laterally to form a series ofmeandrine ridges, generally 2-3 millim. apart, at the surface of thesponge. Surface of basal lamina very uneven under lens, honeycombedwith round openings "25 to -75 miUim. in diameter ; thetrabecula between the openings is hirsute with projecting spicules ;surface of vertical ridges uneven, densely hirsute with projectingspicules and skeleton-fibres, towards the base it has a honeycombedappearance similar to that of the basal lamina. Consistence in spiritslightly resistent, but soft, compressible, elastic. Colour in spiritbuflf-yellow.Main skeleton—arrangement subrectangular ; fibre dense, paleamber-yellow, echiuated sparsely below surface of sponge by spiculeno. 2, set at right angles to fibre. Primary fibres approximately verticalto surface, terminating on it in short horny points densely clothedwith spicule no. 1, which are directed outwards, parallel to the axisof the fibre ; diameter of fibre about -05 to -1 millim. ; cored withproper spicules, usually biserially arranged, to a variable distance,not exceeding •? millim., below surface ; distance of fibres apartabout -17 to '35 millim. Secondary fibres uucored, •()35-'07 millim.thick, placed at intervals of about '17 millim., approximately verticalto primaries. Dermal skeleton composed of a rather close rectangularly-meshedreticulation ; fibres about •04--07 millim. thick,apparently covered in parts by a thick incrustation of foreignbodies. Sarcode transparent, very pale yellow-brown.Spicules :—(1) Acuate, or with slightly constricted base, eithersmooth or with the base minutely spined, moderately curved, taperinggradually from base to sharp point ; size -023 by -01 1 to "013 millim.(echinating the apices of primary fibres). (2) Spined acuate, straighta head slightly indicated by a subterminal neck, spines minute tomoderate-sized, placed at right angles to long axis ; size of spicule•075 by -0063 millim. (echinating fibres of main skeleton). (3) Subspinulateor acuate, smooth, almost straight, tapering gradually from