154 CEYLON PEARL OYSTER REPOET. 



tissues between the fibres, especially in the dermal membrane (Plate X., fig. 8, o). 

 When fully developed they are slightly curved and somewhat hastately sharp -pointed, 

 measuring about 0'072 millim. by 0'00265 millim. 



R.N. 58 (Gulf of Manaar) ; 321 ; ? 346 (distinguished from the type chiefly by the 

 numerous well developed oxea arranged uniserially in the slenderer fibres of the 

 dermal skeleton and multiserially in the stouter fibres ; while the spicules themselves 

 are occasionally strongylote). 



Ceraochalina multiformis, LEKDENFELD, var. manaarensis, DENUY Plate VII., fig. 2. 

 1889, Pachychalina multiformis, var. manaarensis, DENDY (3). 



I identify with this variety a single specimen attached to a pearl oyster, which is 

 represented in Plate VII., fig. 2. A feature which I omitted to mention in my 

 original description of the variety is the echination of the fibres of the dermal 

 skeleton by projecting oxea, singly or in groups. 



The species was recorded by LENDENFELD (51) from Australia and New Zealand. 



R.N. 98 (Gulf of Manaar, dry). 



Ceraochalina ceylonica, n. sp. Plate VII., fig. 3 ; Plate X., fig. 6. 



Sponge (Plate VII. , fig. 3) massive, irregular, sometimes clathrous, with a slight 

 tendency to become lobose or digitate. Surface strongly and copiously aculeated 

 by sharp-pointed conuli about 4 millims. in height ; minutely fibro-reticulate between 

 the conuli. Vents numerous, scattered, about 4 millims. or 5 millims. in diameter ; 

 the openings of deep, cylindrical oscular tubes. Colour (in spirit) pale brown ; 

 texture firm and tough, but compressible and resilient. The largest specimen 

 (R.N. 5, figured) measures 200 millims. by 160 millims. in horizontal dimensions, bv 

 90 millims. in height. 



The main skeleton is a very strongly developed, irregular or rectangularly meshed 

 network of stout, horny fibre, containing usually a large number of small oxea 

 scattered irregularly throughout the spongin substance, but almost always more or 

 less parallel with the long axis of the fibre. Occasionally (R.N. 5) the spicules are 

 much less strongly developed and may be completely absent from some of the fibres. 

 Numerous spicules also occur scattered between the fibres. The thickness of the 

 fibres is variable, say about 0'08 millim. for the primaries and not much less for the 

 secondaries 



The dermal skeleton is a polygonally meshed network of fibre containing a very 

 large proportion of spongin and a good many spicules. The latter are, for the most 

 part, imbedded in the spongin substance more or less longitudinally ; at frequent 

 intervals, however, little groups of oxea, or single spicules, project more or less at 

 right angles from the fibre in an echinating manner, and thus give a rather 

 characteristic appearance to the dermal skeleton. The meshes of the dermal 



