190 THE VOYAGE OF H.M.S. CHALLENGER. 



The rarity of the spined stylote spicules and their occurrence mainly (almost solely) 

 in the oldest part of the sponge suggest the possibility of their being rudimentary 

 and derived from some ancestral form which possessed them in abundance. 



Localltij. — Off Bahia ; shallow water. One specimen. 



Off Bahia; depth, 7 to 20 fathoms. One specimen. 



Raspailia jlagelliformis, Ridley and Dendy (PL XXXIX. fig. 1). 



1886. Raspailia Jlagelliformis, Eidley and Dendy, Ann. and Mag. Nat. Hist., ser. 5, vol. xviii. 



p. 482. 



Sponge (PI. XXXIX. fig. 1) erect, stipitate, branched; stem short and stout, rigid; 

 branches cylindrical, very long and slender, flexible and whip-like ; tapering slightly 

 towards the free end and never anastomosing with one another. Total length of sponge 

 about 425 mm.; length of stem 44 mm.; greatest diameter of same 12"5 mm.; diameter 

 of branches about 4 mm. Colour in spirit yellowish-grey. Texture; each branch 

 consists of a dense, tough, horny looking axis, of darkish colour, coated with a thick 

 layer of a soft, rather friable, yellowish substance, which is easily peeled off so as to leave 

 the axis clean. Surface very minutely hispid. Oscula small, scattered. 



Skeleton. — Containing a very large proportion of horny matter accumulated in a well- 

 defined central axis which is also densely charged with the stylote spicules. In this 

 central axis the spicules are arranged in not very definite tracts, which, instead of being 

 truly longitudinal in direction, are slightly oblique, and cross one another at very acute 

 angles, giving rise to a somewhat lattice-like arrangement ; the spicules are, however, very 

 densely packed throughout the whole axis, so that no large open meshes appear. From 

 the central axis there radiate outwards and obliquely upwards, through the soft tissues 

 towards the surface of the branch, abundant but loose bands of sjDiculo-fibre, formed of 

 spicules like those found in the axis ; these bands terminate at the surface in a dense 

 velvet-like pile, composed of tufts of small, slender, stjdote or subtylostylote spicules 

 whose apices project for a very short distance beyond the surface. 



Spicules. — Megasclera ; of one form only, viz., smooth, very slender styli, straight or 

 nearly so, very sharply but not very gradually pointed at the apex ; measuring in the 

 surface tufts about 0'3 by 0-0032 mm. (very often shorter), and in the deeper parts of 

 the sponge about 0*45 by 0*009 mm. 



This sponge has a considerable resemblance both in external form and in its spicula- 

 tion to Rasimilia ausfraliensis, Ridley,^ from Port Darwin, but differs in being branched, 

 in its thicker and more friable cortical layer, and in the smaller size of its spicules ; with 

 the exception of the character of the external form, the same remarks aj)ply to its 

 relations to the reticulate Raspailia clathrata, Ridley '' from Torres Strait. 



Locality. — Simon's Bay, Cape of Good Hope ; depth, 10 to 20 fathoms. One specimen. 



' Zool. CoU. H.M.S. " Alert," Brit. Mus., 1884, p. 460, pi. xlii. figs, m, m'. Op. cit., p. 461. pi. xli. fiy. F. 



