loO APLYSTNOPSIS. 



posed o£ bands O'04-O-l millim. broad. The meshes in this network are round, 

 rather irregular, 0-03-0"08 millim. wide. The membranes spread out in these 

 meshes are free from foreign bodies. In each two to four oval inhalant pores 

 are situated, which are O'0 1-0-03 millim. wide. When distended these pores 

 occupy nearly the whole of the mesh, aud then nothing remains of the sieve- 

 membrane but a few fine threads between the pores. 



From each mesh a canal, 0-08-0-1 millim. wide, leads down into a system of 

 anastomosing tangential canals, which undermine the skin. The most slender 

 of these are 0*06 millim. wide. They join to form larger stems, which converge 

 and open into the upper ends of large perpendicular canals 1 millim. wide, 

 which extend down into the interior of the sponge. These inhalant canal-stems 

 are 2-3 millim. apart ; annular strictui-es are observed in them. Sleuder branches 

 are given off from these stems in great abundance. The ciliated chambers are 

 somewhat irregularly spherical, 0-033 millim. wide, and destitute of special 

 efferent canals. 



Geographical Distribution. — East coast of Australia : Port Jackson, 

 N. S.W.iLeadc'Hfeld). 



Aplysinopsis digitata, n. sp. 

 (Plate XII.) 



Erect massive sponges, with large, regularly cylindrical, digitate processes. 

 The whole sponge attains a height of 250 millim. The processes are straight, 

 and uniformly 20-30 millim. thick. Erom the upper rounded end a cylindrical, 

 about 15 millim. broad and 10-20 millim. long tube arises, which surrounds 

 the osculum. On the summit of each of the three to six processes observed, 

 one osculum 10 millim. wide is situated. A straight, regularly cylindrical tube 

 — the oscular tube — extends downwards from each osculum ; this is uniformly 

 10 millim. wide, and situated axially in the processes, so that the latter appear 

 regularly tubular. Below, in the massive basal part of the sponge, these 

 oscular tubes are continued in the shape of curved, somewhat tortuous canals, 

 which do not anastomose, however. 



The surface is covered with blunt conuli, 2-5 millim. high and 2-4 millim, 

 apart. 



The colour of the living sponge is light red on the surface and dirty grey in 

 the interior. 



The skeleton consists of main fibres 0-3 millim. thick, and simple connecting- 

 fibres 0-16 millim. thick. Large sand-grains form an axial column in the former. 

 In the latter pith-cylinders 0-1 millim. wide are observed. 



The inhalant canal-system is similar to that of A, elegans. The large inha- 

 lant stems are perpendicular to the surface and terminate close to the wall of 

 the central oscular tube. The exhalants have a more irregular course, and are 



