HIRCTNIA. 181 



thick at the base, and thins out toward the sharp margin. The cup grows out 

 from a basal mass o£ varying size. On the inner surface conuli 2-3 millim 

 high are observed, situated in rows, which form irregular ridges on the surface, 

 often anastomosing to form a network with irregular polygonal meshes. The 

 outer surface is covered with irregular, short, digitate processes 10 millim. 

 thick, which are rather irregularly distributed, and often coalesce to form 

 lamellar outgrowths with sharp margins. The whole of the outer surface is 

 covered with very small conuli 0*5 millim. high. The oscula are 3 millim. 

 wide, and scattei*ed over the outer surface of the cup-shaped sponge. The 

 colour of the living sponge is dark reddish brown on the surface, and 

 intensely orange-yellow in the interior. These colours are retained by spirit- 

 specimens. 



The skeleton consists of longitudinal fascicles of fibres, in which large sand- 

 grains are contained, chiefly at the joining points of the slender fibres which 

 form the trellis-like fascicles. The connecting-fibres are mostly simple, 0-07- 

 0*1 millim. thick, and attached to the main fibres by numerous diverging roots, 

 which are about 0-05 millim. broad. The longitudinal fascicles are 0-8 millim. 

 broad, and the individual fibres uniformly 0-04-0-07 millim. thick. The meshes 

 are 2-3 millim. wide, roundish. The filaments are very abundant, smooth, and 

 hyaline, 0-004-0'007 millim. thick ; on the surface of some of them brown 

 spots are observed. The terminal knots are oval, 0*008 millim. broad. 



Geographical Distribution. — West coast of Australia : Western Australia 

 {Bailey). East coast of Australia : Illawarra, Port Jackson, N". S. W. (Len- 

 denfeld). 



Hircinia arenosa, n. sp. 



Cup-shaped, more or less pedunculate sponges, which are either tall and 

 slender, much higher than broad, or low and flat, extended horizontally. In 

 every case the cup-shaped part of the sponge is very regularly conic. The tall 

 and slender specimens attain a much larger size than the others, being often 

 250 millim. high. The peduncle is short, cylindrical, and distended above, so 

 that it does not appear clearly distinguished from the upper cup-shaped portion 

 of the sponge. The wall of the cup is in large specimens very uniformly 12 

 millim. thick. In the smallest I have seen the wall measured 8 millim. The 

 free margin is pretty regularly circular, and lies in a plane perpendicular to 

 the axis of the sponge. The tall specimens with a peduncle are particularly 

 regular in shape. Those, however, which are not pedunculate, and also the 

 smaller horizontally extending ones, are more irregular ; in these the margin 

 is uneven, slightly undulating. The free margin is rounded off. The surface 

 of smaller specimens is always perfectly smooth, and also the largest have a 

 perfectly smooth inner surface. On the outer surface of very large specimens 



