174 STELOSPONGIA. 



they extend from the base to the margin of the cup-shaped sponge. Occasionally 

 they are branched under very sharp angles, so that there is a much greater 

 number of bands at the margin than at the base, and the interval between the 

 bands remains fairly uniform throughout. The bauds are composed of densely 

 woven longitudinal main fibres, which are 0*2 millim. thick, on an average 

 0'3 millim. apart, and cored with a very slender axial thread of small longi- 

 tudinally disposed foreign spicule-fragments. They are joined by connecting- 

 fibres, which appear distended in the plane of the adjacent main fibres, and 

 often fused to form perforated plates. They are 0-2-0-24 millim. thick, and 

 free from foreign bodies. The meshes are 0-04-0-4 millim. wide and perfectly 

 round. The connecting-fibres are straigat or slightly curved, 0-12 millim. 

 thick : the meshes between them are square or irregular, slightly rounded at 

 the corners ; the larger ones are on an average 1 millim. wide. 



In the skin of well-preserved specimens small, conuli-like protuberances, 

 0-05 millim. high, are observed. In each of these a large granular cell with oval 

 nucleus is situated. In the point of the conic process a small, very strongly 

 refringent granule can generally be detected. I am rather inclined to regard 

 these structures as sense-organs, although the granular cell in the little 

 conulus does not differ essentially from the ordinary granular cells which are 

 abundant in the skin. 



G-EOGBAPHiCAL DISTRIBUTION. — American coast of North Atlantic : Bahamas 

 (Boiverhank OolL). 



North coast of Australia : Darnley Island, Torres Straits (Macleay). Nor- 

 thern Territory, S. A. {Haaclce). West coast of Australia : "Western Australia 

 {Baily). East coast of Australia : Port MoUe, Q. {Ramsay). 



Stelospongia pulcherrima, n. sp. 



(Plate X.) 



Elegant, cup-shaped, regularly conical sponges, attaining a height of 200 

 millim. and a width at the margin of 130 millim. The sponge is slender, 

 higher than broad, and attached by a narrow base. The wall of the cup is about 

 8 millim. thick, and thins out towards the narrow, continuous, and regularly 

 circular margin. The inner surface is covered with longitudinally disposed 

 anastomosing ridges, which cover it with a network of meshes 15 millim. long 

 and 2-5 millim. wide. The outer surface is covered with very much higher 

 and more conspicuous, sharp and narrow ridges, which project about 4 millim. 

 over the concave fields between them ; they are on an average 9 millim. apart. 

 In the upper half they extend regularly longitudinally and do not anastomose ; 

 in the basal half they form a very regular reticulation with polygonal meshes 

 about 10 millim. wide. The limit is very clearly defined, parallel to the margin. 



