SPONGES. 109 



This species appears to be very closely related to CARTER'S Stdlettinojms 

 tuberculata (18), an Australian species from which the Ceylon spouse differs chiefly 

 in its external form and reptant habit. 



RN. 242 (Stat. XXVII., Cod Bay, Trincornalee, 5 fathoms). 



Asteropus, SOLLAS (15). 

 Epipolasidae with two sorts of asters, oxyasters and sanidasters. 



Asteropus haeckeli, n. sp. Plate V., fig. 3. 



The single specimen is a small, irregular crust which has probably been attached by 

 the base, to which fragments of calcareous debris are still adherent. The upper 

 surface rises up into a broad, low, mammiform projection, with a single, rather large 

 vent (about 2 - 5 millims. in diameter) at its apex. Surface smooth, but uneven and 

 harsh to the touch, owing to the presence of huge oxea lying tangentially beneath 

 the surface or projecting slightly beyond it. Colour (in spirit) pale grey. Texture 

 internally coarse and cavernous, owing to the large exhalant canals.* Inhalant pores 

 scattered. The specimen may be only a fragment of a much larger crust ; its 

 maximum breadth is about 25 millims., and its greatest height (where the vent is 

 situated) about 1 1 millims. 



The skeleton is a very dense and very confused interlacement of huge oxea, 

 sometimes collected into very loose, ill-defined, coarse strands, which run towards 

 the surface. 



Spicules. (I.) Oxea (Plate V., fig. 3, a); usually large and stout, fusiform, 

 gradually and fairly sharply pointed at each end ; curved ; varying much in size, up 

 to about 1'9 millims. by 0'065 millim. Numerous much shorter and more slender 

 forms also occur, which may be immature. 



(2.) Sanidasters (Plate V., fig. 3, c, d); with straight, slender axis dividing into 

 two spines at each end, and with two irregular whorls of spines dividing the total 

 length into three approximately equal parts ; or with the axis irregularly spined, and 

 perhaps angulated, so that the whole closely resembles a Spirastrella microsclere ; 

 total length up to about O'OIG millim. These spicules are very abundant at the 

 surface and also common in the interior. 



(3.) Oxyasters (Plate V., fig. 3, b) ; with few, slender, very slightly spined or 

 roughened (? sometimes smooth), sharp-pointed rays and no distinct centrum ; total 

 diameter measured up to about 0'04 millim. These spicules are found in the interior 

 of the sponge, but are scarce and easily overlooked. 



The ectosome is very thick, and composed of a mixture of cystenchymatous and 

 collenchymatous tissue, slightly fibrous in places, and with numerous darkly staining, 

 oval cells scattered through it, which somewhat resemble the symbiotic Alga; of 

 Hexadella, and are probably of a similar nature. 



* The oscular tube is occupied by a Polychsete worm. 



