PLECTODENDEON. — CLIONA. 67 



attains a heiglit of 200 and a width of 250 millim. I have seen in other 

 museums some specimens which appeared to me to be at least twice the size 

 of the largest in this collection, The surface is pretty even and smooth ; 

 the projecting ends of the spicules in the surface-tufts, however, give it a 

 roughness clearly perceptible to the touch, although not perceptible to the 

 eye : a faint and regular network, with meshes 1'5 millim. wide, makes 

 its appearance on the surface ; it is the result of the tissue in the inter- 

 stices of the surface-tufts being of a darker hue than the tufts themselves. 

 Colour in spirit light brown, uniform throughout. Inhalant pores are found in 

 the slight depressions between the surface-tufts only ; they lead into tangential 

 canals situated 0-3 millim. below the surface; these canals are 0-2 millim. high 

 (diameter in a radial direction), and tangentially very much extended, so as to 

 form true subdermal cavities. The exhalants join to form rather wide, oval 

 canals, 1 millim. in diameter, which are the beginnings of oscular tubes ; the 

 latter terminate in oval oscula, situated in the meshes of the sponge-net ; they 

 measure 1 to 2 x 7 millim. and are faii'ly numerous ; no oscula are ever found 

 on the face of the flabelliform sponge. 



Skeleton. — The irregular reticulation of loose and scattered spicules in the 

 interior becomes more regularly fibrous towards the surface ; the bundles 

 terminate in widely extended surface-tufts. The whole of the skeleton consists 

 of spindle-shaped, slightly curved, sharp, and at one end gradually pointed, 

 tylostylote spicules, measuring 0*24 x 0-008 millim. ; the bulb measures 0-014 

 millim. in diameter; it has the shape of a depressed rotation ellipsoid, and is 

 situated terminally ; the distal surface is quite flat and level, vertical to the 

 axis of the spicules. Thus the spicule attains the shape of a nail. 



Geographical Disteibution. — East coast of Australia : Port Jackson, 

 N. S.W. (-RfWHSrt^/). North coast of Australia: Torres Straits (Macleay); 

 Northern Territory, S. A. (Haaclx). 



Genus CLIONA. 



Boring Suberitidse, the skeleton of which consists of smooth 

 tylostyh. 



Cliona, sp. ? 



The holes which this sponge bores in shells are 0-4-l*l millim. wide 

 and very regularly circular; they lead into irregular canals, which re- 

 peatedly curve and pervade the whole of the shell. I have not observed the 

 sponge itself, only the holes which it bores, and can therefore not give any 

 description. 



Geogeaphical Disteibution. — East coast of Australia : Port Jackson, 

 K. S. W. (Lendenfeld). New Caledonia (Ramsay). 



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