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

382 COLLECTIONS FROM MELANESIA.fibres rounded-angled meshes, "14 to -21 millim. in diameter, betweenthe primaries, which are about •i2 millim. apart. Skeleton-fibresamber-yellow in colour, usually homogeneous in appearance throughout.Primaries cored to some little distance from surface by ausuallj' single series of small foreign bodies : secondaries uncored.Sarcode dull pale brown, subtransparent. Texture of sponge inspirit very tough and elastic.Hah. Alert Island, Torres Straits, 7 fms.[^Distribution. " Australian Seas " {LcunarcJc) ?]HIPPOSPONGIA.Sclmhe, Zeitsch. luiss. Zool. xxxii. p. 614.Under this head, owing to the sheet-like aggregation of theskeleton-fibres on the different surfaces, and the large tubular cavitiesformed by the excretory canals, I am for the present includingthose Spongiidae with maeaudrine main excretory canals, as Cacospongiacavernosa., Esper, and Spongia intestinalis, Lamarck, as asubdivision of the genus. Characters may, perhaps, in the futurebe discovered in their soft parts to justify their separation fromthat genus. The following is a third species referable to this sectionof Hippospongia.5. Hippospongia derasa*. (Plate XLI. fig. A.)Sponge subglobose ; surface and interior of skeleton honeycombedby meeandering and branching excretory canals 2 to 3 millim. indiameter at the surface, opening into larger s])aces at a short distancewithin the sponge. Texture of sponge firm, but elastic, in drystate ; colour buff, becoming ochreous in parts.Skeleton at surface between openings of canals smooth and compact,as if pared by a knife ; walls of canals smooth. Primary fibressimple, straight, either ( ) cored and set at right angles to surface, but1not projecting beyond it, diameter, where not distended by foreignbodies, -05 millim. ; or (2) not cored by foreign bodies, set a2:)proximatelyat right angles to cored primaiies, diameter about '035millim. Secondaries forming either subrectangular or irregularmeshes between the primaries ; diameter -018 to '022 millim.Diameter of the ultimate meshes -07 to -14 millim. ; distance betweenprimary fibres "IS millim. Fibre dense, homogeneous, elastic ;colour pale amber-yellow.Hah. West Island, Torres Straits (washed up).The single dry specimen is subhemisphcrical, and measures 60millim. (2|- inches) in length by 35 millim. {l\ inch) in height.The species is most nearly allied to H. (Sjjongia) intestinalis, Lamarck,but has the fibres only about two thirds the stoutness ofthose of that species, and it is subglobose instead of being elongatedand tubular. The texture of intestinalis is coarser and harsherthan that of this species, partly owing to the thickness of the fibres* Drrado, to rub down, in allusion to the smootbiiess and compact textureof the Burf'ace.