464 COLLECTIONS FROM MELANESIA. 



LEUCOPHLffiUS. 



Carter, Ann. $ Mag. N. II. 1883, xii. p. 823. 



92. Leucophlceus fenestrates. (Plate XLII. fig. s.) 



Massive, suberect, terminating above in thin edges, on each side 

 of which open wide pouch-like vent-cavities, which also open to tho 

 surface laterally by rounded apertures. Surface minutely undulating, 

 but glabrous. Texture in spirit rather tough, compressible, soft ; 

 colour dull greyish brown. Main skeleton composed of irregular, very 

 loose tracts of spicules, 3 to 10 spicules broad, extending in various 

 directions and lying at various angles ; the dermis is supported 

 by some closely set subvertical tracts of similar character lying 

 between the subcortical crypts. Dermal skeleton composed of very 

 loose and irregular tracts or aggregated masses of spicules inter- 

 crossing so as to form an almost continuous sheet, in the intervals 

 of which are placed the pores. Sarcode pale brown, subtransparent. 

 Spicule smooth straight, or almost straight acuate, tapering gra- 

 dually from centre to moderately sharp point, and from centre 

 gradually to well-rounded undilated base, which has, however, only 

 about half the diameter of the centre of the shaft ; size of spicule 

 •5 to -8 by -019 to -022 millim. 



Hob. Port Darwin, 8-12 fms. ; bottom sand and mud. 



The height of the single specimen is 38 millim., greatest diameter 

 (at base) 20 millim. ; it forms an irregular, elongated pyramid, with 

 the apex flattened out and somewhat twisted. In size and shape 

 of the spicules the species resembles Hymeniacidon crustula, Bower- 

 bank (Mon. Brit. Spong. ii. p. 185), from the British Seas, which is, 

 however, massive or mammillated and, owing to the inferior diameter 

 (•012 millim.) of the spicule, shows the slenderness of the basal end 

 much less distinctly. It is nearly related to L. massalis, Carter 

 (I. c), from W. Australia, but is darker in colour, is less distinctly 

 penicillate, and has the spicule rather larger. 



Leucophlceus fenestratus, var. (Plate XLIII. fig. g.) 



A dry, upright, flattened specimen, which has grown around a 

 Hydroid bush, appears closely allied to the above species. It appears 

 to have formed part of a long wall-like mass, 70 millim. (24- inches) 

 high and 15-20 millim. thick. Like it, it is surmounted by pyra- 

 midal processes, and is traversed from the upper surface downwards 

 by large cloacal spaces. Colour white, with a tinge of green. The 

 spicules differ from those of the typical form in measuring 

 •9 by - 032 millim. : as, however, a small series of specimens of this 

 species from the western part of the Indian Ocean (see Part II. 

 of this work) includes within itself as great a variation in this 

 respect a<5 is shown by these two Australian specimens, I do not 

 assign distinct varietal names to these two, at first sight, very 

 distinct Australian specimens. 



Hah. Arafura Sea, 32-36 fms. ; bottom sand, mud, and shells. 



