230 AULENA. 



surface is composed of fibres 0-09 millim. thick, which are different from the 

 main fibres in the interior, inasmuch as conic projections arise from their outer 

 side, which are about half as high as these fibres are thick. These conic pro- 

 tuberances are densely echinated, and on an average as far apart as they are 

 high. There are no spines in the spaces between them. From these tangential 

 fibres, perpendicular echinated fibres extend to the surface. The latter contain 

 foreign bodies — sand-grains, which, however, are smaller than those in the 

 main fibres of the interior. The perpendicular fibres, which abut with trumpet- 

 shaped extensions on the dermal sand-cortex, are slightly branched, 0-0067 

 millim. thick, and very densely and regularly spined. The spicules are straight, 

 abruptly pointed, cylindrical styli, 0'067 millim. long and 0-006 millim. thick. 

 There are no spicules scattered in the ground-substance. 



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

 JS". S. W. {Lendenfeld). 



Aulena gigantea, Lendenfeld. 



Hahne gigantea, E. v. Lendenfeld, " Second Addendum to the Monograph 

 of the Australian Sponges," Proceedings of the Linnean Society of New 

 South Wales, vol. x. part 4, p. 847 (1886). 



The varieties of this species differ from each other only in their external 

 appearance. They consist of a basal mass, which may have a diameter 

 of 100 millim., attached by a broad base. It varies very much in height, 

 forming sometimes half or more of the whole sponge, and reduced at other 

 times to a low lamella. Digitate processes grow out from the upper 

 side of the basal mass ; these are either irregular with bulbous outgrowths, 

 or slender and conic, or also regularly fusiform, thickened in the middle. 

 These processes attain a length of 400 millim., and a greatest width of 

 60 millim. The whole sponge is hollow, so that the digitate processes 

 appear tubular, closed at the ends. The central cavity is about as wide as the 

 wall is thick. The latter consists of an exquisitely honeycouibed structure ; it 

 is perforated by large polygonal canals, which lead from the outer surface to 

 the central tube, and which in their course extend centripetally downwards. 

 These tubes are, in the variety micropora 3 miUim., in intermedia 5 millim., 

 and macropora 7 millim. wide. The septa between these tubes are formed by 

 lamelliB only 1 millim. thick ; they terminate in the surface in a regular reticula- 

 tion with polygonal meshes. The free margin is slightly thickened, so that the 

 superficial holes which lead into these tubes are smaller than the tubes are 

 wide. These marginal thickenings are about 2 millim. wide. The colour of 

 all the varieties in spirit and when dry is dark brownish grey. In the 



