sroxGinu. 451 





the proportions of the spicule. Ehlers (Espersch. Spong.) assigns 

 a bihamatc to that species *. 



80. Rhaphidophlus procerus. (Plate XXXIX. fig. K ; 

 Plate XL1I. figs, o-o" .) 



Erect, cylindrical, or very slightly compressed. Stem tapering to 

 a point above, commencing with a cylindrical approximately smooth 

 basal portion, about (5 millim. in diameter ; it gradually increases in 

 diameter towards the middle, where the antero-posterior diameter 

 is 7, the lateral diameter 8 millim. ; the lateral surfaces show a 

 tendency to develop a succession of low upwardly-projecting emi- 

 nences ; the anterior and posterior surfaces of this (middle) division 

 of the sponge are covered with closely-set rounded papillae, 1-2 

 millim. apart, 1 millim. broad by '5 to 1 millim. high ; the upper 

 fourth tapers gradually to the apex and is approximately smooth, 

 the papillae of the median part becoming gradually obsolete here. 

 Xo true branches (only two small cylindrical processes on one 

 side close together, near the middle). Base formed by several 

 branched roots, 3 to 5 millim. in diameter. Surface smooth between 

 and over eminences, compact, soft and velvet-like to the touch ; no 

 vents visible to the naked eye. Texture in spirit firm, very slightly 

 compressible, flexible, very tough ; colour pale grey. 



Main skeleton consisting of a close network of amber-coloured 

 horny or dull subopaque yellow horny sarcodic fibre, the primary 

 lines of which are about *2 millim. apart and are placed vertically 

 to the surface, the secondaries also about - 2 millim apart, crossing 

 the intervals between the primaries at approximately right angles ; 

 to the fibres are attached by their bases large numbers of the larger 

 smooth spinulate spicule, whose points project outwards and upwards 

 at acute angles to the fibre. Dermal skeleton formed of a single 

 thickness of distinct, but overlapping, dense tufts of the smaller 

 smooth spinulate spicule, one or more of the spined acuate spicules 

 occupying the centre of eaoh tuft ; the spicules are attached by 

 their blunt ends, and the points radiate outwards over the dermis. 

 Sarcode pale yellowish brown, somewhat granular. 



Spicules : — (1) Smooth spinulate ; head distinct, suboval, rather 

 narrower than middle of shaft ; shaft tapering gradually to sharp 

 point from about middle ; size *36 by •0127 millim : in fibre of 

 main skeleton. (2) As (1), but measuring -28 by -0079 millim. ; 

 forming tufts in dermis. (3) Spined acuate, with well-rounded, un- 

 dilated base, tapering to sharp point from base ; spines usually 

 absent from the apex and just above base, stout, sharp, those of 

 median portion of spicule more or less recurvate towards base ; size 

 •11 by '0127: in centre of dermal tufts and sparingly in main-skeleton 



* Spongia cactiformis, Lamarck (Ann. Mus. Hist. Nat. xx. p. 440), is also a 

 Bhaphidophlus, differing from B. arborescens, so far as the material at my dis- 

 posal shows, mainly in the non-spinulation of the smooth acuate. 



2g2 



