THALASSODENDBON. 



223 



Thalassodendron digitata, n. sp. 



The sponge consists of a mass of stout digitate processes, which are more 

 or less upright and grow oat from a broad basal mass. The processes are 

 inflated at the base, conic, tapering towards the abrupt end, which bears a ter- 

 minal osculum. The surface of the skeleton appears peculiarly villous. 



The sMeton consists of spiculiferous main fibres and aspiculous con- 

 necting-fibres. The former are 0-05 millim. and the latter 0-03 miUim. 

 thick. The spicules in the former are slender, terminally thickened, straight 

 or irregularly curved, strongyla 0-2 millim. long. The main fibres are 

 echinated by smooth and stout, blunt styH, 0-1 miUim. long, and at the base 

 0-01 millun. thick. The echinatiug styh are often confined to the distal 

 surface of the fibres. 



G-EOGKAPHiCAL DISTRIBUTION.— North coast of Austraha: Torres Straits 

 (Macleay). 



Thalassodendron typica, u. sp. 



Horizontally expanded, broad, irregularly caliculate or flabelliform and 

 curved sponges. The free margin of the cup is pretty narrow, and generally 

 incised at one place, so that the whole structure does not appear radially sym- 

 metrical. The sponge attains a height of 200 miUim. The margin of the cup 

 measures in large specimens 250 miUim. in diameter. The surface is covered 

 with radially situated, longitudinal ridges which are about 8 mUHm. apart. The 

 wall of the cup has an average thickness of 12 millim. 



The shdeton consists of mam and connecting-fibres. The former are O'll 

 mnUm. thick, and filled with spicules ; the latter 0-05 miUim. thick, and aspi- 

 culous. The spicules in the former are straight styh, 0-2 millim. long, and 

 0-005 millim. thick. They are sUghtly echinated by styh, scarce, stout, smooth 

 or sUghtly spined, 0-03--007 millim. long, and at the base 0-008 millim. thick, 

 often entirely imbedded in the horn-substance of the fibre. 



Geogeaphical Distribution.— East coast of Austraha (Bamsay). 



Thalassodendron rubens, n. sp. 



Large, branched, erect sponges, which consist either of a bunch of digitate 

 processes, or which appear more flabelliform. The branches are about (3 milhm. 

 thick. The surface is slightly grooved. 



The skeletoa consists of a network of fibres, 0-03-0-2 millim. thick, which 

 contain somewhat irregularly disposed styh, 0-15-0'25 millim. long and 0-004- 



