CHALINOPSILLA. — PHYLLOSPONGIA. 115 



very rarely branched, never bent at their joining-points with the secon- 

 daries, perpendicular to the main fibres, which they connect, and 0-015 millim. 

 thick. The thickness of the secondaries varies from 0-0033-0-01 millim. 

 The meshes of the network are irregularly rectangular, 0*27 millim. wide. 



Geographical Distribution. — South coast of Australia : Port Phillip, V. 

 (F. Midler, Lendenfeld). 



Genus PHYLLOSPONGIA, 



Frondose, caliculate, or branched, never massive, lamellar Spon- 

 gidae ; with smooth, granular, or grooved siirfjxce and numerous 

 oscula. CiHated chambers spherical, 0*02-0"04 millim. wide, with 

 special efferent canals. Fibres of the supporting-skeleton slender. 



Phyllospongia velum, n. sp. 



The sponge has the shape of a curved lamella attached by a narrow base. 

 From the base, and also from the concave side of the lamella, small, lobose 

 or baud-shaped fronds grow out. There are often anastomosing ridges on the 

 concave face. The sponge attains a height of 200 and a breadth of 160 miUim. ; 

 the average thickness is 3*5 millim. . The main lamella together with the 

 small fronds form an irregular cup more or less open on one side. The sur- 

 face is smooth and slightly undulating. Oscula are scattered over the greater 

 part of the inner side of the cup. On the outer surface oscula are also present, 

 but not near so numerous, and always clustered in such places opposite which 

 there are no oscula on the inner surface. It is therefore quite correct to say 

 that the vents are distributed in a one-sided manner. The oscula are 1 millim. 

 wide and 6 millim. apart. Spirit-specimens are soft, flexible, and elastic. 

 Dry specimens which have not been washed out are pretty hard ; the colour 

 of dry specimens is whitish or light brown. 



The surface-skeleton consists of a network of horny fibres, without foreign 

 bodies. The termini of the main fibres of the supporting-skeleton, which abut 

 on the surface, are connected by straight, stout, primary tangential fibres 

 0-06 millim. thick. Three to five, generally four, such primary fibres radiate 

 from each main-fibre terminus. The wide interstices between these fibres 

 are occupied by a fine network of secondary tangential fibres, which are 

 much branched and continually anastomose ; these are 0-03 millim. thick, 

 and the meshes between them 0-15 millim. wide. In the dermal membrane 

 abundant sand-grains and other foreign bodies are found between the fibres 



