2. W. H. ROW—REPORT ON THE SPONGES : NON-CALCAREA. 301 
DIASTRA STERRASTRHA,n. sp. (PI. 35. fig. 4; Text-fig. 4.) 
This sponge is represented in the collection by a single specimen. It 
consists of an erect, somewhat rounded mass growing on a thin sheet of 
calcareous matter, possibly coral. The specimen shows a tendency to become 
lobose, but is not actually divided into lobes. It is, however, not a complete 
specimen ; so that the typical external form of the species may differ from 
that of the specimen here described. The fragment obtained is about 35 mm. 
in height by 25 mm. in diameter. The surface of the sponge is slightly 
grooved, and these grooves run nearly vertically down the sponge, but 
they do not seem to be connected either with oscula or pore-areas, or to be 
otherwise important. 
A considerable number of oscula occur scattered over the surface of the 
sponge. They are of greatly varying size, but ail are quite small, the largest 
/ 
Fig. 4.— Diastra sterrastrea. Development of spherasters, x 700. 
seen not exceeding 1:0 mm. in diameter. They are of very irregular shape, 
and hardly possess the usual characteristics of oscula. There is no oscular 
skeleton at all, nor can any oscular membrane be distinguished. They open 
directly, however, into the canal-system of the sponge. 
The pores are scattered all over the sponge surface, and are not collected 
into pore-areas. ‘They appear on the surface of the sponge as minute light 
spots, clearly showing up against the darker colour of the sponge. ‘This is 
apparently a pore-membrane ; and almost always in the centre of the light 
spot was a dark hole, undoubtedly the pore itself. In some of the pore- 
membranes no pore could be distinguished, presumably owing to its complete 
closure by the contraction of the membrane. 
The colour in spirit is dark brown throughout the sponge. 
The texture of the sponge is firm, but neither hard nor tough, nor is the 
sponge easily compressible. If bent out of its proper shape it immediately 
recovers it on being released. 
The ectosome is differentiated into a cortex, which possesses a special 
skeleton in the form of a special layer of oxea in its deeper parts. The oxea 
