niBcixiA. 183 



0*1 millim. wide, and join to form larger canals with irregular annular strictures. 

 These lead from the outer layers of the sponge into the central layer, and 

 there open out into one of the oscular tubes, 0-5-1 millim. wide, which extend 

 longitudinally upwards in this layer, then bend abruptly round and open out 

 by the oscula on the inner surface. These oscular tubes show vexy distinct 

 annular strictures at pretty frequent intervals. The two superficial layers, the 

 one below the inner and the other below the outer surface, have the same 

 structure. 



The ground-substance in the vicinity of the ciliated chambers is charged 

 with pretty abundant granules. The ground-substance in the central layer, 

 however, which lies in the vicinity of the oscular tube, contains alike no ciliated 

 chambers, no small canals, and no granules. Cells appear to be scarce in this 

 tissue. Stellate elements are observed at long intervals. Just below the 

 surface of the oscular tubes circular muscles are observed ; these are particularly 

 well developed in the annular strictures. 



Some specimens of this sponge are rather similar to Pliyllospongia vasiformis. 



Geogeaphical Distribution. — West coast of Australia : "Western Australia 

 (Baily). South coast of Australia : Port Phillip Heads, V. (-S. Wilson). East 

 coast of Australia : Port Jackson, W. S. W. (Lendenfeld). 



Hircinia halmiformis, n. sp. 



The sponge consists of a meandrically folded lamella, 15-30 millim. thick, 

 and attains a breadth of 75 millim. and a length of 85 millim. The surface is 

 perfectly smooth. The oscula are 2 millim. wide, scattered over the whole of 

 the surface, and on an average 5 millim. apart. They lead into a system of 

 anastomosing lacunose oscular tubes in the interior of the sponge, which might 

 perhaps be considered as vestibular cavities of the exhalant system, being rather 

 similar to the exhalant vestibular spaces of certain species of Halme. 



The skeleton consists of a pretty uniform network of loose columns of large 

 sand-grains, 0*8 millim. thick. The meshes formed by this network are elon- 

 gate, oval, on an average 2 millim. long and 0*8 millim. broad. The sand- 

 grains in the column are on an average 0*2 millim. apart, and connected by 

 short, straight, and unbranched spongin-fibres, 0-03-0'05 millim. thick. Each 

 sand-grain is enveloped by a thin coating of spongin. 



Geographical Distribution. — West coast of Australia : Western Australia 

 {Baily). 



