542 A. MONOGRAPH OF THE AUSTRALIAN SPONGES, 



Skeleton. (Plate XXXVI., fig. 4.) 



The main fibres are continuous from the base, apparently to the 

 extremities of the net sti'ucture of this sponge. This species in 

 every respect pi-esents many peculiarities, which stamp it to a 

 transition form between the genera Euspongia and Hippospongia. 

 Also the main fibre show in some places indications of a similarity 

 with those of Hippospongia. 



The main fibres are on an average 0'5 mm. apart, often however 

 two or three extend for a long distance parallel and remain close 

 together. 



The fibres are completely filled with sand. The grains of this are 

 small. The surface is roughened by numerous knobs, which often 

 attain a height equal to half the diameter of the fibre. 



The sand grains average 0-U09 mm. The thickness of the main 

 fibre is 0'038 at the thinnest, and 0-14 mm. at the thicker parts. 



The connecting fibres form a network of meshes measuring on 

 an overage 0-2 mm., in width in the interior of the sponge. Here 

 they are 0"05 mui., thick. The connecting fibres do not contain 

 any foreign bodies. 



On the surface another kind of network is met with. The 

 meshes are narrower and the fibres thinner, and the whole structure 

 is more irregular. This surface skeleton is however by no means 

 always present and may be a pathological structure, caused 

 locally to make its appearance where cammensols have taken up 

 their abode. 



Nothing is known of the histology of this species. 



Geographical Distribution. 

 East Coast of Australia. Port Jackson, (Ramsay.) 



Bathymetrical Distriuution. 

 30-40 metres. 



