108 CIIALINOPSILLA. 



regularly dichotomously dividing processes. It attains a height of 400 millirn. 

 The branches are cyliudrieal, on an average 12 millirn. thick, and taper to 

 conic sharp-pointed ends. From a stout stem, which is attached ■ by a 

 trumpet-shaped, extended base, and has a thickness of about 20 millim. and 

 a leno-th of 40 millim., three or four branches grow out. All the branches 

 originate from the upper end of the stem and extend upward and slightly 

 outward. They are dichotomously branched, exceptionally one of the branches 

 is thicker than the other ; as a rule, however, this is not the case. At 

 the branching points they are much widened and compressed, particularly 

 near their distal, often nearly flabellar ends. The oscula are scattered and 

 numerous, slightly prominent, 2 millim. wide and 5-7 millim. apart, often 

 situated in longitudinal rows. The surface, apart from the prominent 

 oscula, is smooth and sliglitly undulating. The dry skeleton is light greyish 

 brown; spirit-specimens are darker. When dry, the sponge is hard and 

 resisting ; in spirit, however, soft, elastic, and easily compressible between the 

 fingers. 



The surface-skeleton consists of a simple network, without a distinction of 

 primary and secondary fibres. The suji^Jortim/skeleton is composed of main 

 and connecting-fibres. The former extend longitudinally in the axes of the 

 digitate jjrocesses, where they form occasional and irregular anastomoses. 

 From these axial supporting fibres branches are given off, which extend 

 towards the surface in a plumose fashion and enclose an angle of about 15° 

 with the longitudinal axial fibres. They are slightly branched, but do not seem 

 to form anastomoses, except close to their base. They are 0*2 millim, thick 

 and 0*5 miUim. apart. Thinner ones, however, are by no means rare, and 

 the thin main fibres appear more approximated to each other than the thicker 

 ones. The numerous ramifications of these main fibres and their varying 

 thickness renders the whole structure more irregular than the skeleton of most 

 other species. The connecting-fibres are, for the most part, simple connections 

 of adjacent main fibres perpendicular to the latter ; occasionally, however, they 

 appear slightly branched. They are, on an average, 0-06 millim, thick and 0*5 

 millim, apart, and joined to the main fibres by trumpet-shaped extensions of 

 their bases ; the meshes accordingly appear well rounded off. All the fibres 

 are charged with foreign bodies — siliceous spicules, sand, &c. ; these form an 

 axial thread in the main fibres of the supporting-skeleton, which is about half 

 as thick as the fibre, and surrounded by a clear layer of spongin. At the 

 joining-points of the connecting-fibres these columns of foreign bodies are 

 drawn out to form conic points, which extend some distance into the con- 

 necting-fibres. In the connecting-fibres themselves an often interrupted 

 series of foreign bodies is observed, which lies axially, and appears as a con- 

 tiuuatiou of the conic protuberances on the columns in the main fibres above 



