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

;SPONGIIDA. 389rounding tissues. The paler colour, to the natural eye, of the lattersponge appears to be due to the greater concentration of the pigmentwithin the cells : a similar effect is produced by a similar cause insome Cephalopoda {Loligo).IG. Dysidea digitifera. (Plate XLI. fig. C.)Curved and anastomosing cylindrical digitations, about 3 millira.in diameter, arising from the upper aspect of an erect, compressed,irregular basal mass, and tapering gradually to pointed ends. Surfaceeven, minutely roughened by the presence in the dermis of acoarse, reticulate, horizontal skeleton. Yents few, scattered on mainmass of sponge, subcircular, leading deeply into sponge. Textnre(in spirit) very friable ; colour pale greyish brown. Main skeletoncomposed of large foreign bodies, united by a thin, almost colourlessmembrane (not visible unless the fibre is broken) ;primary* fibresrunning approximately at right angles to surface ; secondaries{tertiunj of Marshall) approximately parallel to surface, very shortmeshes narrow, about -07 to -09 millim. broad, rounded ;fibres -019to -Oo millim. thick. Dermal skeleton formed of fibre similar tothat of the main skeleton, about -025 to -055 millim. thick, formingcircular or oval meshes, -032 to "09 millim. broad. Sarcode palegreyish brown, rather granular.Bah. Albany Island, Torres Straits, 8 fms.This is a delicate species, distinguished from all other describedspecies by its closed digitate processes (those of D. callosa. Marshall,bear vents) ; in being devoid of connli it differs from most species,but seems to agree with Diisklea lirl-ii, Carter (Ann. & Mag. N. H.(5) vii. p. 374), ? Bowerbank.Height of sponge 40 millim. (1^ inch) ;greatest lateral extension25 millim. (1 inch) : longest individual digitation, 20 millim.(4 inch). The sponge has grown up amongst and over some specimensof Eudendriam.17. Dysidea semicanalis. (Plate XLT. fig. B.)A hollow flattened vertical common stem, giving rise to severalvertical cloacal tubes, some of which are open on one side (evidentlyformed in some cases by the folding over of surface-ridges),united more or less by their projecting knife-like adjacent edges. Tubesabout GO millim. {2^ inches) in greatest length ; mean internal diameterabout G millim. ; contracted at mouth, their walls 3 to 4 millim.in greatest thickness ; inner surface provided with a few shallowpits. Outer surface bearing a few long, but not prominent, ridgesrunning from near base to near the upper end; surface between ridgeseven, minutely honeycombed in dry state by small, longitudinallyelongated spaces, separated by fibres of dermal skeleton, and about 5millim. in their smaller diameter. Texture, in dry state, rather harshto the touch, firm but elastic, compressible and somewhat tough.Colour pale yellowish brown.* Secondary of Marshall, primary of Hyatt, vertical of Carter.