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

8P0NGIIDA. 473101. Stelletta purpurea.(Plate XL. fig. E ; Plate XLIII. figs, j, /.)Free, subspherical or suboval. A single circular vent (about 2millim. in diameter in moderate-sized specimens) often present ; itleads deeply into the sponge. Surface subpapillose, i. e. embossedwith small semiglobular elevations, visible most readily under alateral light. Colour purple in spirit, when well preserved. Adistinct cortical layer with sarcode of the same consistency as thatof the central part of the sponge, about '7 millim. broad, containingthe subcortical crypts, and formed (in adult specimens) by the spaceintervening between the heads of the superficial zoue-spicules ;a subcortical zone of anchors and smaller zone-spicules. Deepsarcode transparent, brownish yellow ; that of surface purplishred, rather granular.Spicules:— (1) Zone-spicule ; shaft stout, tapering gradually tosharp point, 1'4 to 1-6 by -045 to -06 millim. ; arms strong,tapering gradually to sharp points, projectiug somewhat forwardat the commencement, and then curving backwards slightly, "27by -043 to '06 millim. in length and breadth respectively, (2)Anchor, long, tapering to sharp point ; head almost flat above ;arms turning rather abruptly back to form an angle of about 45°with shaft, tapering to sharp points ; expanse of arms at theirpoints •! millim. ; diameter of shaft about •035 millim. : length ofshaft about 2 millim., of arms about '07 millim. Head usually lyingbelow the zone of " chones. " (3) Body acerate, long, slender,tapering very gradually from centre to sharp points ;size about 1*5to 2 by -037 millim. (4) Minute stellate of flesh; about 7 to10 arms ; no percex^tible body ; arms straight, very slender, viz.about -0008 millim. in diameter, apparently smooth, terminatedby minute head ; diameter of spicule across arms -02 to -025millim. : distributed throughout all parts of the sarcode.JIab. Prince of Wales Channel, Thursday Island, and WestIsland, Torres Straits, 4-9 fms. ; bottom sand or sand and coral.Port Darwin, 7-12 fms. ; bottom sand and mud. Arafura Sea oflfN.W. coast of Australia, 32-36 fms. ; sand, mud, and shells.Specimens not abundant at any of the stations. The singlespecimen from West Island is remarkable for being half coveredby specimens of lotrocliota purpurea, RMzocJialina sinr/aj)orensis,Cladochalina niida, and a coralline.Stelletta purpurea, var. retroflexa. (Plate XLIII. fig. h.)This name may be appliedto a specimen which has the expanseof the arms of the zone-spicule somewhat greater than in the typicalform, while their diameter is less, and one or more of the armsgenerally has the point bent backwards abruptly, so as to form anangle of about 135° with the rest of the arm. The specimen isglobular, and has a vent about 1-5 millim. in diameter. The bend