S0LLA8ELLA. — SPIBASTRELLA . 67 



structure similar to that of the choua; ot the Geodidae are found ; these are 

 0"15 iinllim. wide, and communicate below with extensive lacuna) which separate 

 the cortex from the pulpa of the sponge. The latter form a nearly continuous 

 subdermal cavity 0*l-0*2, millim. wide. The interior of the sponge is lacuuose ; 

 the greater part of the space is occupied by very irregularly curved canals 

 with a pretty uniform width of 0*25 millim. 



Skeleton. — The skeleton of the pulpa consists of irregularly situated, 

 isolated, and more or less curved oxea measuring 0*7 X 0-008 millim. ; these 

 spicules are cylindrical, and abruptly pointed ; one end generally more blunt 

 than the other. Irregularly disposed bundles composed of large styli, which 

 measure 2x0*045 millim., and which are often accompanied by bundles of 

 the smaller kind described above pervade the pulpa. The bundles in the 

 subcortical layer, composed chiefly of large styli, extend tangentially and 

 longitudinally. We also observe bundles composed nearly exclusively of the 

 smaller kind of spicules, extending in a radial direction and connecting the 

 surface-tufts with the internal skeleton. The surface-tufts themselves are 

 distally as broad as the fields above described, and composed of oxea and styli, 

 which measure 0-5-0-6 x 0-01-0-012 millim. 



Geographical Distribution. — East coast of Australia {Eamsay). 



Familia SPIRASTE,ELLID.ffi. 

 Monaxonia with spirastrellid microsclera. 



Genus SPIRASTRELLA. 



Massive Spirastrellidse with stylote or tylostjlote megasclera ; 

 microsclera, stellates, and short-spiiied stronglya. 



Spirastrella australis, n. sp. 



Large and massive lamellar sponges, 10-20 millim. thick, attaining a height 

 of 300 millim. and to a breadth of 250 millim., attached by a small base. 

 The surface of the lamella is very smooth and even ; the lamellae are slightly 

 curved, and the surface is generally more smooth on the concave than on the 

 convex side ; oscula 1 millim. wide, scattered over both the concave and convex 

 surfaces. Colour of surface in spirit light brown; the same colour in the 

 interior. The canals, which extend from the uniforiuly scattered inhalant 



