SPONGES.-HALLMANN. 



127 



developed, stout fibres composed of styli. Surface conuli, 

 each forming the centre of a radiate system of slender 

 fibres. There is a dermal layer of discasters of the larger 

 kind. Megascles : — Blunt-pointed styli J65 x 11 }i, 

 together iviih a few {probably immature) sharp-pointed, 

 slenderer spicules ivhich attain an equal length. Micro- 

 scleres : — Discasters of two kinds, of which the larger 

 form a superficial layer and a packing round the main 

 fibres, and are also scattered through the ground sub- 

 stance along with the smaller. The larger are provided 

 with simple spines, the smaller often with compound 

 spines, the spines in both cases being arranged in four 

 whorls, two at either end. 



The single specimen consists ot a sessile, submassive, erect, 

 cylindrical main portion, together with a similar but smaller 

 upgrowth which arises partly from the substratum in con- 

 tinuity with the base of the former and partly from its side. 

 The main trunk is 70 mm. in height, and 30 mm. in diameter. 

 The surface, which is smooth and glabrous, is provided with 

 numerous spine-like conuli, i to 3 mm. in height. There are 

 no oscula. The surface is closely dotted with minute pore 

 areas, about .2 mm. in 

 diameter, and each with 

 two to four pores. The 

 texture is dense and com- 

 pact, the consistency firm 

 and fairly tough ; in both 

 respects the sponge is 

 somewhat suggestive of 

 india-rubber, although, of 

 course, not so dense, 

 homogeneous or elastic. 

 The colour (in spirits) is 

 pale brownish-grey. 



The main skeleton con- 

 sists of a very loose reti- 

 culation of stout fibres (up 

 to 400 mm. or more in 

 thickness) which are com- 

 posed solely of densely 

 packed parallel styli. 



Each surface-conulus forms the apex of a convergent pencil of 

 fibres, of which the axial or principal fibre only is derived 

 from the main skeletal reticulation, whilst the remainder — 

 which are very much slenderer fibres — both begin and termin- 

 ate at the surface. Probablv it would be more correct to sav 



r\ 



KJ 



Fig. 24— Lah'iDicii/ia coniilosa. a 

 Styli. b Larger discaster. c Smaller 

 discasters. 



