440 COLLECTIONS FKOM MELANESIA. 



shallow depressions, covered by a glabrous semitransparent mem- 

 brane, rendered rough by the projection of the low ends of the 

 primary fibres, "25 to -5 millim. apart (many smooth patches occur) ; 

 texture in spirit brittle, compressible (specimen No. 1), rather tough, 

 elastic (specimen No. 2) ; colour pale greyish (specimen No. 1) or 

 reddish brown (specimen No. 2). Internal structure cavernous, 

 loose. Vents numerous, scattered, circular or oval, leading deeply 

 into sponge ; diameter 1-5 to 3 millim. 



Main skeleton regular, rectangular in arrangement ; primary 

 fibres set at right angles to surface,' '18 to -35 millim. apart, -013 

 to -03 millim. thick ; secondary fibres at right angles to primaries, 

 •18 to -35 millim. or upwards apart, similar to primaries in propor- 

 tions ; fibres wholly composed of foreign bodies united by an almost 

 colourless, not dense, substance. Dermal skeleton formed by small 

 foreign bodies scattered abundantly over the dermis, tending to 

 aggregate into slightly denser anastomosing tracts about -14 millim. 

 broad, enclosing rounded meshes about -IB to -SS millim. in dia- 

 meter, and by the cylindrical spicules of the sponge, which by loose 

 aggregation form tracts, about 4 to 6 spicules broad, below the 

 skeleton of foreign bodies, the tracts branching and anastomosing 

 not unfrequently, and ending freely on the surface in slightly 

 expanding tufts ; sarcode subtransparent, granular, colour a warm 

 brown (slightly in specimen No. 1 , strongly in specimen No. 2, in 

 which it is more dense. Spicules: — (1) Slender acerate, smooth, with 

 veryi()6lightly enlarged subpyriform basal end, the other end rather 

 bluntly pointed ; size about -16 to -19 by -0021 by -0032 milKm. : 

 forming part of dermal skeleton and scattered over main skeleton- 

 fibres. (2) Contort bihamate, smooth, curve moderately strong, 

 points sharp, ^ddenly and sharply bent inwards ; size -032 by -002 

 millim. : abundant in subjacent tissues. (3) Tridentate equiancho- 

 rate, shaft well curved, about "0016 millim. thick ; teeth slender, 

 sharp, curved inwards, about '008 millim. long ; spicule "022 millim; 

 long. Foreign bodies small in specimen No. 1 ; large, for the most 

 part, in specimen No. 2. 



Hob. Specimen No. 1 : Prince of Wales Channel, Torres Straits, 

 7-9 fms. ; bottom sand. Specimen No. 2 : Port Jackson, 0-5 fms. 



Two specimens in spirit. No. 1 has apparently been torn from a 

 larger mass ; it is much penetrated by some thin Algse, on which it 

 seems to have grown much as Amorphina panicea grows over weed ; 

 it measures 60 miUim. by 22 millim. in its two chief dimensions. 

 No. 2 is somewhat compressed on one side, and measures 36 by 

 19 by 12 millim. The anchorate spicule is scarce in one of the 

 specilnens (that from Port Jackson), while it is abundant in the 

 other. 



The variability in colour and texture, aind perhaps in the secon- 

 dary fibres, is considerable, but not surprising, considering the 

 distance between the stations at which the specimens were obtained ; 

 in other points the agreement is close. The species is a very dis- 

 tinct one, differing from both Marshall's species in the presence of 

 a well-defined reticulate skeleton and of an anchorate flesh-spicule, 



