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

•;480 COLLECTIONS FROM MELANESIA.106. Geodia globostellifera. (Plate XLIII. fig. b.)Carter, Ann. >Sf Mag. N. H. 1880, vi. p. 134, pi. vi. fig. 38.I have been able conclusively to determine the true relations ofthe globostellate spicule to the sponge, which Mr. Carter appearsnot to have felt quite safe in regarding as really belonging toit. As, however, I find it to occur not only in the cortex of differentparts of the same sponge and in different specimens, butsometimes also in the sarcode beneath the crust of balls, it must beregarded as truly a production of, and thus proper to, the spongeitself. I find, what Mr. Carter does not describe, a small aceratespicule which forms small tufts on the surface, generally accompaniedby the globostellate, and probably related specially to theorifices of the canal-system. Like Mr. Carter, I have been unableto find any " anchors."My measurements of the spicules do not quite correspond with thosegiven by Mr. Carter ; but as these do not quite agree with his figures,I do not attach much importance to the discrepancy. In his descriptionthe globostellate has the same diameter (viz. j^^^ inch) assignedto it asto the shafts of the zone-spicule and body acerate, whereasin the plate, where it is figured (at fig. /) as on the same scale(" scale D," magnified 32 diameters) as those spicules, it appears asonly about one third of their diameter.The following are the chief spicular measurements from the presentspecimens :•—1. Zone-spicule (the arms of which are simple, as in Mr. Carter'sfigure, not trifid) : diameter of shaft -07 millim., of arm at baseabout '048 millim. ; expanse of any two arms together about•58 millim.2. Body acerate, 3"0 millim. long by "038 thick.3. Fork (the only one seen) : diameter of arms and shaft•016 millim. ; length of arm 1 millim.4. Geodia-ball, long diameter -09 millim.5. Globostellate, diameter -028 millim.6. "External" stellate (forming, with the globostellate, the outerpellicle, but, like it, also occurring sparingly in the subcorticalsarcode), •0063 millim. in diameter. Its arms are numerous andappear to end bluntly.7. " Internal " stellate (the arms are few in number and areusually curved), -038 millim. in diameter.8. Surface acerate; about '16 millim. long by -005 millim. indiameter.The largest specimen is about 80 millim. (3-i inches) in its greatestdiameter ; and the two specimens (which are preserved in spirit) aretinged with crimson in places, as if this was their colour during life.Hah. Port Darwin, north coast of Australia, near tide-marksbottom sand and rock.Distribution. Gulf of Manaar, Ceylon {Carter).The great interest of this species has induced me to devote some