160 HA.LME. 



Halme villosa, Lendenfeld. 



Aulena villosa, E. v. Lendenfeld, " A Monograph of the Australian Sponges. 

 — Part V. The Auleninac," Proceedings of the Linnean Society of New 

 South Wales, vol. x. p. 309 (1885). 



Massive, spherical, or oval sponges attached by a small base, but never 

 pedunculate, attaining a height of 40 millim. and a breadth of 30 millim. 

 The colour of the living sponge is yellowish grey, but seems to be subject to 

 variations. In spirit and dry it appears dirty grey. The surface is covered 

 with abundant cylindrical, terminally rounded conuli, which are about "2 millim. 

 high, 0*8 millim. thick at the base, and 1*4 millim. apart. The direction in 

 which these conuli protrude from the surface varies. They invariably radiate 

 from a common centre ; but this centre may be situated further up or lower 

 down, as the case may be. In some specimens this centre coincides with the 

 centre of the sponge, and the conuli stand perpendicular to the surface ; in 

 others, again, it lies near the base of the sponge, and then the conuli tend 

 upward. It appears that the locality where the sponge grows has something 

 to do with the position of the conuli. These conuli are soft and resilient, and 

 move with the water-currents, so that the sponge appears villous. Between 

 the conuli very fine, soft, and tender membranes, perforated by large cix'cular 

 pseudoscula, which lead into the system of vestibular lacunae below, are spread 

 out. These vents are circular, and situated in groups of 1-4 ; they measure 

 2-5 millim, in width. The difference between this and other species of Halme 

 lies in the fact that in them the body consists of lamellae, and in this species 

 of cylindrical trabeculae. Whilst in most species of Halme the vestibular lacunae 

 are simple empty spaces between the sponge-lamellae, they are traversed by 

 numerous fine membranes (which subdivide them into smaller, more or less 

 spherical compartments) in H. villosa. These compartments are connected by 

 large circular pores in the membranes which are spread out between them. 

 It is apparent that by movements of these membranes the direction and force 

 of the water-current can be gx-eatly influenced. We find that there are 

 nervous and muscular elements in these membranes, by the united action of 

 which, no doubt, the water-current is regulated. The meshes of the network 

 formed by the true body of the sponge measure 1-2 millim. in width ; this is 

 the extent of the vestibular lacunae. 



The compartments into which the vestibular spaces are divided are more or 

 less spherical, and measure 0*2-0*5 millim. in width. This structure has a 

 froth-like appearance, and fills the whole of the vacant space in the meshes. 

 The thickness of the membranes is on an average 0*017 millim. The circular 

 pores in them are situated in the middle of the fields, limited by the lines where 

 the membranes join. They are pervaded by slender horny fibres which siq:)- 

 port them. 



