114 CHAI/IKOPSILLA. 



are more branched than in most other species, 0'3 millim. thick, and 1-1"5 

 millim. apart ; these fibres contain numerous scattered axially- situated 

 sand-grains, which average 0*4 milhm. in size. The connecting-fibres 

 ■are unbrauched and very scarce ; they measure 0*1 millim. in thickness 

 and are 1-2 millim. apart. There are no foreign bodies in the connecting- 

 fibres. 



GEOQiiAPmoAL DiSTBiflUTiosr. — South coast of Australia : Port Phillip 

 Heads, V. (B. Wilsoji). 



Chalinopsilla repens, Selenka. 



Ditela repens, E. Selenka, " Ueber einige neue Schwamme aus der Siidsee," 

 Zeitschrift fiir wissenschaftliche Zoologie, Band xvii. Heft 4 (1867), 

 Seite 567. 



Euspongia repens, R. v. Lendenfeld, " A Monograph of the Australian 

 Sponges. — Part VI. The Genus Eusjwngia," Proceedings of the Linnean 

 Society of New South Wales, vol. x. part 3, p. 524 (1885). 



Digitate, repent, and irregular incrusting sponges. The digitate parts 

 occasionally coalesce to form lamellose extensions ; usually, however, they 

 remain isolated. They attain a length of 100 millim., are cylindrical, ter- 

 minally rounded, and 12-20 millim. thick. The surface is slightly roughened 

 by indications of conuli. No sand is found in the skin, which is protected by 

 a dense tangential network of fibres. The oscula measure from 2 to 4 millim. 

 in width, are circular, and occasionally slightly raised over the surface ; they 

 are situated terminally, but also occur on the sides, particularly of large and 

 irregular digitate portions. 



The skeleton is very tender and soft, and can be pressed between the leaves 

 of a book like a flower. The colour of the sponge in spirit is yellow ; the 

 skeleton is grey, with a brownish hue. 



The surface-skeleton is composed of a dense and uniform network, the 

 fibres of which have an average thickness of 0-017 millim.; the meshes are 

 0-05 millim. wide and rather irregular. The main fibres of the supporting- 

 skeleton extend in a longitudinal direction along the oscular tube, which 

 occupies the central part of the hollow digitate processes. These fibres emit 

 branches, which curve gracefully towards the surface and terminate in the 

 superficial skeleton; they are on an average 1 millim. apart, measure 0*08 

 millim. in thickness, and are filled with sand-grains, which cause the surface 

 of the fibre to become very knotty. In the interior of the sponge a very re- 

 gular network of c(ranecting-fibres is met with. These are differentiated into 

 primaries and secondaries : the former are simple, straight or slightly curved, 



