494 MH. S. O. RIDLEY ON SOME 



Vents numerous, apparently only on inner surface of cup; round; 

 diameter 1 to 3 mm. 



Main Skeleton. — Arrangement rather irregular. The stout, 

 somewhat flexuous primary fibres run approximately at right 

 angles to the surface ; they are connected, usually at short ('2 to 

 •43 mm.) intervals, by secondary fibres, which run at angles varying 

 from 45° to 90°, with the primaries, and are often curved. Pseudo- 

 ceratinous (antea, p. 481) material pale yellowish brown in upper 

 part of sponge, extending beyond the margins of the skeleton-spi- 

 cules ; does not polarize light. Primary fibres ending on surface by 

 anastomosis with a dermal set of secondaries, or projecting beyond 

 it to a distance not exceeding *4 mm. on the inner, 1*5 mm. on the 

 outer surface of sponge. Both primary and secondary fibres filled 

 with parallel smooth acuates, apparently of two sizes ; both gene- 

 rally 8 to 15 spicules broad, and both echinated at short intervals by 

 single-spined cylindrical spicules, which project at right angles to 

 the surface of the fibre, and are attached by their extreme base. 



Dermis. — Fibres very tortuous, stout, forming meshes of very 

 various size and generally rounded outline ; echinated by large 

 numbers of the cylindrical spicule. 



Barcode. — In dried state transparent yellowish brown ; that of 

 the surface, however, almost covered by minute patches of a 

 granular reddish pigment. 



Skeleton-spieules of two kinds : — (1) Smooth acerate (pointed 

 at both ends), more or less bent, rather sharply, tapering to sharp 

 points from within 3 diameters of the ends ; size from 26 to '32 

 by "014 mm. ; occurring in all the fibres, and occasionally free in 

 sarcode near fibre. (2) As no. 1, but size from '19 to '25 by *011 

 to '0127 mm. ; form the greater part of the fibre. 



Echinating spicule. — Cylindrical, blunt at both ends, tapering 

 from attached end, which is about twice the diameter of free 

 end ; covered with spines, especially thickly at ends ; spines pro- 

 minent, sharp, the basal ones projecting at right angles to the 

 axis of spicule, the remainder curved towards base ; size *1 to "12 

 mm. by -0095 to "0126 mm. 



Sab. "Southern Ocean" (Peron Sf Lesueur ap. Lamarck); 

 pearl-oyster bed on N."W. coast of Australia, and "W. Australia ? 

 {Brit. Mm. coll.). 



Examined. Dry and in balsam. 



Obs. Two specimens of this species are known — the type spe- 

 cimen in the Paris Museum(e/! Lamarck, loc. cit.), and a fine speci- 

 men recently purchased for the British-Museum collection. 



The latter is a remarkably fine and attractive specimen ; has 



