HALICHONDRIA. 81 



of 0*07 millim. ; the meshes of the network are more or less quadratic, 0-35 

 millim. wide. The fibres are composed of irregular spicule-buudles. The 

 spicules are straight oxystrongyla with sharp or bluut points, 0*2 millim. long 

 and 0-006 millim. thick. Similar but more slender spicules are scattered 

 abuudantl}^ through the ground-substance. 



GrEOftRAPHicAL DiSTEiBTJTiON. — East coast of Australia : Port Jackson, 

 N. S. W., 30 metres (Lendenfeld). 



Halichondria rubra, var. digitata, uov. 

 (Plate II. tig. 1.) 



This variety is distinguished from the species //. rubra by the small diameter 

 of its digitate processes, which are also more numerous ; they are cylindrical, 

 and do not exceed 15 millim. in thickness. The sponge attains a height 

 of 300 millim. The surface is roughened in consequence of the main fibres 

 slightly protruding beyond it. The scattered oscula are circular, 3-4 millim. 

 wide. 



The skeleton consists of a network in which main and connecting-fibres can 

 be distinguished. The main fibres measure 0'15 millim. in thickness, and the 

 connecting-fibres 0*07 millim. ; the meshes of the network are 0*35 millim. 

 wide. The spiades are slender and often slightly curved ; they are on an 

 average 0-15 millim, long and 0*004 millim. thick. 



GEOGEAPniCAL DISTRIBUTION. — East coast of Australia : Port Jackson, 

 N. S. W. {Ramsay). 



Halichondria mammillata, u. sp. 



Large, massive, or horizontally extended, cake-shaped sponges of irre- 

 gular shape, from the upper surface of which dome-shaped protuberances grow 

 out. The sponge attains a breadth of 200 millim., the processes are 40-60 

 millim. high, at the base 40 millim. broad, and situated close together. 

 The surface is smooth ; on the summit of each dome a circular osculum, 7-12 

 millim. wide, is situated ; from this a cylindrical oscular tube of the same 

 diameter extends downward. 



The sheleton consists of stout main fibres, which are connected by single 

 spicules and by loose spicule-bundles. The main fibres are 0*12 millim. thick 

 and on an average 0*24 millim. apart. The spicules are mostly straight, excep- 

 tionally also slightly curved, sharp-pointed, oxystrongyla, 0-25 millim. long and 

 0-006 millim. thick. 



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



N. S. W. {Ramsay). 



