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

;spoNGnDA. 397Eah. Thursday Island, Torres Straits.The abrupt termination of the spicules and the stouter fibre distinguishthis form of C. nuda. A single dry specimen, X05 millim.(44- inches) long.25. Cladochalina subarmigera.(Plate XXXIX. fig. H ; Plate XLI. figs. Z, I'.)Repent, tortuous, solid, subcylindrical ; stems 4 to 8 millim. indiameter (2 to 4 in a dwarf form), branching dichotomously atrather long intervals, somewhat fiattened above. Branches of samegeneral character as stems, often increasing somewhat in diametertowards apices, maximum length about 45 millim., attached atvarious points of lower surface. A few sharp points 1 to 2 millim.long project from sides ofstem and branches here and there, especiallyin the neighbourhood of the larger vents ; absent in somespecimens ; surface otherwise even. Vents numerous, in a singleseries, 2 to 6 millim. apart, along upper surfaces of stem andbranches, circular, 1 to 2 millim. deep, 1 to 2*5 millim. in diameterlumen cylindrical ; margins level with the flattened upper surfaceof the sponge. Texture in spirit compressible, elastic, tough ;surface somewhat harsh to the touch ; colour umber-brown.Main skeleton strictly rectangular in arrangement, rather variablein siz.e of meshes and diameter of fibres in diiferent specimens ;thus the distance between primaries is '28 to '77 millim., betweensecondaries "042 to -28 millim. ; diameter of primaries -053 to '09millim., of secondaries "035 to -053 millim. (in dwarf form, primaries-035 to -053, secondaries '023 to -035 millim.) ; fibre almostentirely spicular, a very narrow horny margin alone being usuallydiscernible (rarely in the dwarf specimen) ; spicules 6- to polyserialin primaries, 3- to 5-serial in secondaries (in the dwarf form,4- to 8-serial in the former, 2- to 4- in the latter). Dermal skeletonof irregular wide meshes, composed of fibres of the same structureas those of the main skeleton ; between these a close angular networkof fine unisijiciilar fibre, meshes -053 to '08 millim. in diameter.Horny matter of fibres amber-yellow. Sarcode rich yellowish brown,finely granular. Spicules smooth acerate, slender, almost cylindricalto within three diameters of ends, whence they taper to sharp points ;size -08 by -0032 millim., '09 by -0032, -095 by -002, to -12 by•002 (in difl^erent specimens).Hah. Warrior Ilecf, Alert Island, Thursday Island, Prince ofWales Channel, Torres Straits, 4-7 fms., &c. ; bottom pearl-shellsor sand, &c. Albany Island, X. coast of Australia, 3-4 fms. ; bottommud (dwarf form).A few spirit-specimens represent the larger form of the species,one of them is 105 millim, (4| inches) in maximum extent. A smallspecimen, 25 millim. long, is the dwarf form above mentioned.The species is perhaps most closely allied to Cladochalina armiqera,Duch. & Mich., of described species ; the surface-spines, however,which are the most striking external feature of C. anjn(/era, are