384 COLLECTIONS FEOM MELANESIA. 



fibres, was also obtained. So far as the vents can be made out, 

 tbey are numerous, and occur in a zone just inside the margin of the 

 cup. The primary fibres are very stout at the margin of cup, viz. 

 about '5 to •? millim. in diameter, exclusive of their sandy coating. 

 Hah. Port Molle, Queensland, between tide-marks ; Arafura Sea, 

 off north coast of Australia, 32-36 fms. (the larger specimen). 

 ' The external position of the sand on the fibres recalls Mauricea, 

 Carter (Ann. & Mag. N. H. (4) xx. p. 174), for which see below 

 (Garterispongia). In this point, and in the arrangement, propor- 

 tions, and other characters of the skeleton-fibres, the species strongly 

 resembles Boweihan'k's Polyjlbrospongia ^abellif era (Eroc. Zool. Soc. 

 1877, p. 459), from the north of New Guinea; but the shape of 

 that species is entirely different, being fan-shaped and quite thin,- 

 and the vents are described as inconspicuous. 



7. Stelospongus implexus. (Plate XXXIX. fig. B.) 



Stipitate, with short, usually flattened or compound pedicel ; sub- 

 turbinate, the wall usually proliferating inwards, and then anasto- 

 mosing, forming a chambered cup, with thin walls (2 to 4 millim. 

 thick). Outer and inner surfaces even, the outer marked strongly, 

 in the dry state, by longitudinal projecting skeleton-ridges, the inner 

 slightly so by the subrectangular superficial skeleton-network. Vents? 

 Texture in dry state harsh, but yielding and rather brittle. Colour 

 pale greyish brown. 



Main skeleton at some distance below surface consisting of stout 

 fascicles of primary fibres, vertical to the surface, about "17 miUim. in 

 diameter (the individual fibrils about -025 millim.), densely coated 

 by a mosaic of small sand-grains, connected towards the surface by 

 secondary lines of similar structure, about "07 miUim. in diameter ; 

 the primaries, when near the surface, become cored with foreign 

 bodies, and become more condensed, sometimes forming but a single 

 fibre, -1 millim. thick. Dermal skeleton on exterior of cup consist- 

 ing of parallel single fibres •! to "17 millim. in diameter, coated, 

 and to some extent cored, by small foreign bodies ; intermediate mem- 

 brane sparsely strewn with similar foreign bodies. Saroode pale 

 amber-yellow, transparent. Skeleton-fibre very pale yellow in the 

 small, deep amber in the large fibres. 



Hab. Port Molle, Queensland, coral-reef. 



This species differs in external form from aU those described by 

 Hyatt (Mem. Bost. Soc. ii.). In the only cup-shaped form aUuded 

 to by Schmidt (Atl. Geb. p. 29) the walls would appear to be rela- 

 tively much thicker, as is the case in S. excavatus, mihi {swpra). 

 This form approaches that species closely, the skeleton- and surface- 

 structure being almost identical in the two cases ; but the well- 

 marked tendency to proliferation and formation of secondary cavities 

 in the cup and the shortness of the pedicel further distinguish S. im- 

 plexus. This is a small species : all four specimens obtained (which 

 were dry) were in their natural state between 40 and 60 miUim. 

 high, and between 40 and 60 millim. in greatest diameter at the 

 top. 



