SPONGES. 125 



firm and the specimen contains a good deal of coarse sand imbedded in it. The colour 

 (in spirit) is pale yellowish-grey. The surface is smooth, hut rather uneven. No 

 vents visible. Pores scattered in small groups '. 



The main skeleton is a very dense and confused reticulation of stout megascleres. 

 The preparation only shows very feebly developed surface brushes. 



Spicules. (1.) Tylostyli ; usually curved, with stout, fusiform or sub-fusiform 

 shafts and well-developed ovoid heads ; apex gradually and evenly and fairly sharply 

 pointed. Size when full grown about 0'5 millim. by 0'01'J millim. 



(2.) Spirasters ; short and slender, closely resembling those of var. triucomalicusm ; 

 about 0*012 millim. long; not very abundant. 



R.N. 178 (type of variety), 179 (both from Lagoon, Galle, June, 1902). 



Spirastrella tentorioides, n. sp. Plate V., fig. 7. 



The single specimen bears a striking resemblance in external form to Tentorium 

 semisuberiles, consisting of a short columnar body ending above in a strongly convex 

 and sharply-defined pore- and vent-bearing area of darker colour* than the remainder 

 of the surface. The surface of the column is subglabrous and irregularly furrowed 

 longitudinally. On one side a much smaller column is given off as a vertical offshoot, 

 terminating above like the large one. The specimen is attached below to a mass of 

 calcareous debris by a broad base and narrows somewhat towards the apex of the 

 column. Total height about 24 millims. Diameter of the column in the middle 

 about 15 millims. Colour (in spirit) light grey. There are several wide exhalant 

 canals running vertically through the column, and probably several smallish vents at 

 the apex. Only one vent, however, is now visible, forming the outlet of the largest 

 canal, and measuring only about 1'5 millim. in diameter. The inhalant pores are 

 scattered between the surface brushes of spicules on the rounded apex of the column, 

 around the vents. 



The main skeleton is a very dense, confused reticulation of megascleres, permeating 

 the whole of the soft tissues, close up to the walls of the canals, on the one hand, and 

 to the dermal surface on the other. In this reticulation the spicules lie in all 

 directions, but around the inhalant canals they are mostly placed lengthwise, with 

 their apices pointing upwards. Surface brushes are confined to the rounded summit 

 of the column, where they are well-developed. 



Spicules. (I.) Tylostyli (Plate V., fig. 7, a, h)\ straight or slightly curved, with 

 stout, sub-fusiform shafts gradually and sharply pointed at the apex, and well- 

 developed oval heads ; size when full grown about 6G millim. by 0'0164 millim., but 

 much smaller in the surface brushes. 



(2.) Spirasters (Plate V., fig. 7, c-fj) ; varying much in shape and size, usually 

 slender, but sometimes stout; e.g., (a) short, slender, simply curved, with projections 

 (hardly spines) on the convex side ; length about 0*008 millim. ; (b) short, slender, 

 * The darker colour is due to the entanglement of dirt amongst the spitule-brushe=. 



