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

SPONGIIDA. 42165. Rhizochalina singaporensis, Carter, ysit. (Plate XLI. fig. s.)Pliloeodictyon siugaporeuse, Carter, Ann. ^ Max). N. H. (1883) xii.p. 326, pi. xiii. tig. 17."With this species I identify a series of specimens which usuallyhave tlie outward habit of 2i.Jistulo.sa, but in winch a large proportionof the (usually acerate) spicules have both ends more or lessrounded. In the most perfect specimen the cortex is glabrous,chestnut to purplish-brown in colour, thin ; the fistuhe are wantingon one, presumably the lower, surface. A smaller specimen consistsof a barrel-shaped mass adherent by its lower surface to two othersponges, and giving off from one lateral extremity one, from theother two fistulie and no others. A detached fistula exhibitsfurcation, dividing into two unequal branches at an angle of about3U° to each other. In one remarkable specimen the central part ofthe body is elongate, slightly compressed, and measures 110 millim.(4|- inches) in its present length, while its diameter does not exceed12 millim. anywhere ; in its other characters it agrees well withthe above specimens. A fragment of the bulbous part of a largespecimen shows that part of this specimen, when perfect, to havepossessed a diameter of about 75 millim. (3 inches).The ends of the spicules show almost every stage between amerely blunted point and a rounded end like that of the base of anordinary acuate spicule : some thin, completely acerate forms, whichoccur mixed with the blunt forms in the subcortical tissues, areperhaps the young of the latter, indicating the typical shape fromwhich the adult spicules have diverged. The largest adult spiculeshave nearly the same size as the acerates of the typical form ofR.Jistidosa, viz. -3 by "0127 millim., but they vary immensely inlenr/th; the thin acerates measure "28 by -004 millim. In Carter'sspecimen the acerates measure "3 by -017, the blunt forms •04-"08by -004 millim.Three fistulse retain their ends, and these are finger-like andclosed.Hab. Prince of Wales Channel, West and Alert Islands, TorresStraits, 7 fms.Distribution. Singapore (Carter).I may explain that I had at first distinguished this form as avariety of R.Jistiilosa;but as Mr. Carter has, since then, publisheda description of it as a distinct species, and as T had already feltthat it should perhaps be so described, I assign the name proposedby him to the Australian specimens.56. Rhizochalina spathulifera.(Plate XXXIX. fig. E ; Plate XLI. fig. q.)Main body elongated, flexuous, cylindrical or somewhat compressed,12-17 millim. in greatest diameter. External portion (cortex) in drystate even, hard and dense on the stem, where it is about -7 millim,thick; rather uneven, porous atid compressible on the brandies;