122 LEIOSELLA. 



short, special, efferent canal. The exhalants join to form lacunose canals in 

 the interior, which are pervaded by fine membranes, and which open into the 

 irregularly radially disposed oscular tubes. 



The surface-skeleton consists of a network of stout ridges composed of large 

 sand-grains and spicule-fragments, which are held together by a smaU quantity 

 of spongua cement. The spongin is here and there drawn out to form short 

 and slender fibres connecting more distant sand-grains with each other. 



The main fibres of the supportiug-sTceleton are joined to the surface-net by 

 trumpet-shaped extensions at their distal ends. They are 0*07 millim. thick,, 

 knotty, or even spiny, and fiUed with very irregularly disposed abundant 

 spicule-fragments and sand-grains. The connecting-fibres measure 0-018-0-027 

 millim. in thickness, are slightly curved, and free from foreign bodies ; they 

 form a very irregular network, with polygonal meshes 0-12-0-24 millim. wide. 

 The variability of the thickness of the connecting-fibres is in co-relation with 

 the variability in the size of the meshes. 



Geographical Distribution. — "West coast of Australia : Swan River, W. A. 

 (British Museum). South coast of Australia : Tasmania (British Museum). 

 East coast of Australia : Broughton Island (Ramsay) ; Port Jackson, N. S. W. 

 (Lendenfeld, Ramsay). 



Leiosella silicata, Lendenfeld. 



Emponrjia silicata, E. v. Lendenfeld, " A Monograph of the Australian Sponges. 

 — Part VI. The Genus Euspongia" Proceedings of the Linnean Society 

 of New South Wales, vol. x. p. 545 (1885). 



Small, horizontally extended, lobose, and vertically compressed sponges. 

 The largest specimens attain a length of 70 millim., a breadth of 40 millim., 

 and a height of 20 miUim. The lamellas are on an average 14 millim. thick. 

 The surface is perfectly smooth in the living sponge. There are, however, in 

 hardened specimens, which are always slightly contracted, depressions between 

 the termini of the main fibres in the skin ; the latter then appear as conuli. 

 The oscula are small and numerous, scattered irregularly over the surface, or 

 arranged in rows ; they are circular, measure 1 millim. in diameter, and 

 slightly raised over the surface. The sponge is hard and elastic. 



In the living state this species is of a greyish rose-colour ; in spirit it 

 becomes darker grey on the surface and lighter grey in the interior. The dry 

 skeleton is light brown. 



The inhalant pores measure, when dilated, 0-01 millim. in diameter, and are 

 circular. There are always a great number of pores, often as many as 30 

 in one pore-sieve. The canals which lead down from the pores are oblique, 

 and join to form larger tubes, which extend tangentially and open into the 



