AULENA. 229 



Small, incrusting, horizoutally expanded sponges. From the upper surface 

 irregular lobose processes may arise, which are never higher than broad. The 

 network of the sponge-lamella is dense. The lamellae are on an average 

 1 millim. thick, and the cells of the honeycomb 10 millim. wide. The surface 

 is smooth. Small oscula measuring 0-5 millim. in width are scattered sparsely 

 over the whole of the surface. The colour of fresh specimens is yellowisli 

 grey. In spirit and dry they appear darker brown. The living sponge is very 

 soft and resilient ; dry skeletons are hard and inelastic. 



The skeleton of the interior consists of slightly knotty main fibres 0-2 millim. 

 thick, containing large scattered sand-grains, and connecting-fibres 0-028 

 millim. thick, which are free from foreign bodies. The outermost main fibres 

 are echinated on their external side. Perpendicular fibres 0-027 millim. thick 

 extend from them to the surface; these contain no foreign bodies, and 

 are echinated by very irregularly disposed styli, which are straight, cylindrical, 

 abruptly pointed, and measure 0-067 millim. in length and 0-0048 millim. 

 in thickness. There are no spicules scattered in the ground-substance. The 

 surface is protected by a sand-cortex, on the lower side of which the echinated 

 fibres abut perpendicularly with trumpet-shaped extensions. 



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

 'N.S.^Y.(Lendenfeld). 



Aulena laxa, var. digitata, Lendenfeld. 



ffalme laxa, var. digitata, E. v. Lendenfeld, '■ Second Addendum to the Mono- 

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

 South Wales, vol. x. part 4, pp. 847-848 (1886). 



This sponge attains a height o£ 300 millim. and a breadth of 70 millim. 

 The digitate processes which arise from the basal massive portion of the sponge 

 attain a length of 200 millim. and a thickness of 30 millim. The surface is 

 uneven, undulating. The distal ends of the branches are rounded or cut off 

 abruptly. The meshes of the honeycomb have a width of 20 millim., and 

 the lamella itself is 2 millim. thick. The surface is smooth ; the scattered 

 oscula measure 0-5 millim. in diameter. The colour of the fresh sponge is 

 light grey or white. Fresh specimens are soft and resilient, dry skeletons 

 hard and inelastic. Just below the outer surface, canals 0-11 millim. wide are 

 observed, which appear to communicate ; these represent the subdermal cavity. 

 In the interior the canals measure 0-08 millim. in diameter. 



The internal slceleton is composed of main fibres, 0-07 millim. thick, which 

 are pretty smooth and contain axially scattered sand-grains. The connecting- 

 fibres are 0-008 millim. thick. The tangential net of main fibres below the 



