228 AtJLENA. 



proper spicules in the ground-substance, but sometimes with 

 echinating spicules on the superficial fibres. 



Genus AULENA. 



Aulenidge which consist of a honeycomb-like folded lamella. 

 The fibres of the skeleton are charged with foreign bodies and 

 form a dense network. The superficial fibres are echinated on the 

 distal surface. With sand-cortex. 



Aulena laxa, Leudenfeld. 



Halme laxa, E. v. Leudenfeld, " 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). 



Irregular, decumbent, and hoi'izoutally expanded or massive and erect 

 sponges, with irregular upright digitate processes, which are about 30 millim. 

 thick and 200 millim. high. These processes are rounded at their distal 

 ends, or cut off abruptly. The smaller, more or less incrusting forms attain a 

 length of 60 millim. and a height of 20 millim. The sponge consists of a very 

 loose honeycomb structure, the meandriform lamellae of which are 1-2 millim. 

 thick. The cells of the honeycomb are of varying size, 10-20 millim. wide. 

 There is no central cavity. The surface of the lamellae which appear slightly 

 thickened distally, that is in the outer surface of the sponge, is pretty smooth. 



The skeleton is composed of a network of fibres in the interior. The main 

 fibres contain large scattered sand-grains and are 0*2 millim. thick ; the con- 

 necting-fibres measure 0-02-0*03 millim. The reticulation is very dense, the 

 meshes measuring only 0'2 millim. in width. Prom the outermost main fibres, 

 which form a tangential reticulation, echinated fibres extend to the surface. 

 The fibres of the tangential network are likewise echinated on their distal sur- 

 face. No spicules are attached to the fibres in the interior. These echinating 

 spicules are styli, 0-06-0-067 millim. long and 0-0048-0-006 millim. thick. 

 The surface itself is protected by a layer of sand 0-1 millim. thick. The super- 

 ficial echinated fibres appear to be connected with the sand-cortex. 



Aulena laxa, var. minima, Leudenfeld. 



Halme laxa, var. minima, v. Leudenfeld, " Second Addendum to the Monograph 

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

 South Wales," vol. x. part 4, p. 8^7 (1886). 



