480 COLLECTIONS FUOil 11ELAXESIA. 



106. Geodia globostellifera. (Plate XLIII. fig. b.) 

 Carter, Ann. $ Mag. N. H. 1880, vi. p. 134, pi. vi. fig. 38. 



I have been able conclusively to determine the true relations of 

 the globostcllate spicule to the sponge, which Mr. Carter appears 

 not to have felt quite safe in regarding as really belonging to 

 it. As, however, I find it to occur not only in the cortex of dif- 

 ferent parts of the same sponge and in different specimens, but 

 sometimes also in the sarcode beneath the crust of balls, it must be 

 regarded as truly a production of, and thus proper to, the sponge 

 itself. I find, what Mr. Carter does not describe, a small acerate 

 spicule which forms small tufts on the surface, generally accom- 

 panied by the globostellate, and probably related specially to the 

 orifices of the canal-system. Like Mr. Carter, I have been unable 

 to find any " anchors." 



My measurements of the spicules do not quite correspond with those 

 given by Mr. Carter ; but as these do not quite agree with his figures, 

 I do not attach much importance to the discrepancy. In his descrip- 

 tion the globostellate has the same diameter (viz. -^ inch) assigned 



to it as to the shafts of the zone-spicule and body acerate, whereas 

 in the plate, where it is figured (at fig. /) as on the same scale 

 ("scale D," magnified 32 diameters) as those spicules, it appears as 

 only about one third of their diameter. 



The following are the chief spicular measurements from the pre- 

 sent specimens : — 



1. Zone-spicule (the arms of which are simple, as in Mr. Carter's 

 figure, not trifid) : diameter of shaft *07 millim., of arm at base 

 about *048 millim. ; expanse of any two arms together about 

 ■58 millim. 



2. Body acerate, 3 - millim. long by -038 thick. 



3. Fork (the only one seen) : diameter of arms and shaft 

 •01 6 millim. ; length of arm 1 millim. 



4. Geodia-ball, long diameter -09 millim. 



5. Globostellate, diameter -02S millim. 



6. " External" stellate (forming, with the globostellate, the outer 

 pellicle, but, like it, also occurring sparingly in the subcortical 

 sarcode), *0063 millim. in diameter. Its arms are numerous and 

 appear to end bluntly. 



7. " Internal " stellate (the arms are few in number and are 

 usually curved), '038 millim. in diameter. 



8. Surface acerate; about 'IB millim. long by -005 millim. in 

 diameter. 



The largest specimen is about 80 millim. (3i inches) in its greatest 

 diameter ; and the two specimens (which are preserved in spirit) are 

 tinged with crimson in places, as if this was their colour during life. 



Hab. Port Darwin, north coast of Australia, near tide-marks; 

 bottom sand and rock. 



Distribution. Gulf of Manaar, Ceylon {Carter). 



The great interest of this species has induced me to devote some 



