432 JANE STEPHENS : ATLANTIC SPONGES 



Sometimes one end is rounded off while the other is rather sharply pointed, so that 

 the spicule looks like a stylus. Length , 22-0 , 3 mm. by 0'005-0'007 mm. (7) 

 Sterrasters. — Spheroidal, and slightly flattened, 0'085-0'l mm. in diameter. (8) 

 Somal strongylospherasters. — These have a comparatively large centrum and 

 numerous very short, blunt, knob-like rays. Diameter 0'005-0'007 mm. (9) 

 Spherasters, occurring beneath the sterrastral layer, '01 3-0 '02 mm. in diameter. 

 (10) Choanosomal oxyasters, with usually two to seven rays. The rays are conical, 

 sharply pointed, and covered with minute spines, except at the base. The rays are 

 0'02-0'032 mm. in length by about 0'005 mm. in thickness at their base. The diameter 

 of the whole spicule is 0'045-0'065 mm. Very abundant. 



The arrangement of the excurrent and incurrent openings, the form of the 

 megascleres, and the presence of the cortical anatrisenes in this species recall Geodia 

 miilleri (Fleming). The two species differ especially as regards their microscleres. 

 The somal asters of Geodia littoralis, with their comparatively large centrum and 

 short, knob-like rays, differ in shape from the corresponding spicules of G. miilleri, 

 which are typical chiasters. The spherasters lying immediately beneath the 

 sterrastral layer differ in proportions in the two species, and are more clearly marked 

 off from the other asters in Geodia littoralis than in G. miilleri. The choanosomal 

 asters of the older species are very variable, passing from chiasters to oxyasters, 

 with slender, usually fairly numerous rays. They differ altogether in appearance 

 and size from the oxyasters of G. littoralis with thick rays, which are few in number. 

 The sterrasters of the new species are slightly larger than those of G. miilleri. 



Geodia libera n. sp. (Plate XXXVIII, fig. 6 ; Plate XL, fig. 2.) 



Station 478. Table Bay, shore. May 1904. One specimen. 



Station 482. Houtjes Bay, Saldanha Bay, shore. 19th May 1904. Four 

 specimens. 



The largest specimen, which was collected in Table Bay, is an irregular, nodular 

 mass, 20*5 cm. long by 12 cm., with a thickness of about 9'5 cm. The remaining 

 specimens are much smaller. They are irregularly rounded or oval, and closely 

 resemble small, dark-skinned potatoes in appearance. They are about 65 mm., 

 57 mm., 31 mm., and 28 mm. in length respectively. One of the small specimens is 

 slightly embedded in an Alcyonarian colony, but is nowhere attached to it. The 

 other specimens, including the largest, are a little injured in places, but show no 

 sign of having been fixed to any support. 



The colour in spirit of the largest specimen is dark greyish purple externally, 

 and is yellowish internally, while the smaller sponges are a paler purple outside, with 

 a pale yellow interior. 



The surface is even, for the most part, but harsh to the touch. In places it is 

 strongly hispid. There are no large oscula, nor is there a specially marked oscular 



