166 STELOSPONGIA. 



Stelospongia australis, n. sp. 



The synonyms will be found below in the descriptions of the varieties. 



Pyriform, erect, pedunculate, flabelliform, lobose, or low incrusting sponges, 

 which attain a maximum height of about 300 millim. The varieties S. a, cana- 

 Uculata, S. a. villosa, S. a. conulata, and S. a. fovea are erect, radially symmetrical, 

 more or less pedunculate and pyriform, or club-shaped. Irregular colonies of 

 pyriform individuals of these varieties occur, in which their distal ends 

 remain distinct ; sometimes, however, they may be entirely joined, as occa- 

 sionally in S. a. fovea. In S. a. levis we meet with thick flabellar forms which 

 appear as more or less laterally fused pyriform individuals distinct in their 

 distal portions. S. a. conulissima is small, low, and incrusting. 



The surface is covered with large conuli in all the varieties, with the excep- 

 tion of S. a. levis, the surface of which is partly smooth, and partly covered with 

 small conuli. In the other five varieties the conuli are 1-5 millim. high and 

 1-4 millim. apart. The distal ends of the fascicles of main fibres which 

 support these conuli project in the skeleton as tufts or villi 1*5-10 millim. 

 over the surface. They are longer and more slender in S. a. villosa than in the 

 other varieties. These projecting fascicle-termini are scattered uniformly over 

 the surface, as, for instance, in S. a. villosa ; or arranged in more or less 

 regularly longitudinal rows, as particularly in S. a. canaliculata ; or they are 

 arranged in lines which form a very regular network with polygonal meshes in 

 the surface, as in S. a. fovea. The oscula are always very large and conspi- 

 cuous, 8-12 millim. wide and circular. In the pyriform varieties there is 

 always one osculum only, and this is situated centrally on the summit of the 

 sponge. In the colonies there is, of course, an osculum on the summit of each 

 one of the fused individuals. In S. a. levis an osculum is observed on the 

 side near the summit of each of the processes which rise from the margin 

 of the flabelliform sponge. In S. a. conulissima the oscula are few in number, 

 scattered over the surface, and surrounded by a funnel-shaped tube 8-18 

 millim. long, which is supported by longitudinal fascicles of main fibres. In 

 skeletons these appear as very conspicuous frills round the oscula. 



The colour of living specimens is brown, with a more or less distinct violet 

 tiuge, on the surface, and grey or yellowish in the interior. The dry skeletons 

 are light to dark brown, stiii, but slightly compressible and elastic. 



The main support of the skeleton consists of flattened, band-shaped, occa- 

 sionally also cylindrical fascicles of main fibres, which extend upwards along 

 the wall of the centrally situated oscular tube, and give off branches curving in 

 a plumose manner outwards to the surface. The fascicles are 0'8-6 millim. 

 wide. The most slender are observed in S. a. conulata, where they are cylin- 

 drical ; and the widest in S. a. fovea, where they are exquisitely band-shaped, 

 about 0-7 millim. thick, and here and there 6 millim. wide. These fascicles 



