79 



structure that they doubtless belong to the same species. One of them has the 

 shape of a graceful, thin-walled calyx, the lower end of which has been torn off, 

 but which otherwise is pretty well preserved. The sack-shaped body is about 

 1 cm. high and has an oval transverse section. The upper part is bent outward 

 and forms a horizontally-extending rim 15-20 mm. broad and only 1 mm. thick. 

 This thins out towards the free margin which is destitute of a spicular fringe. 

 Thus the whole sponge has the shape of a hat lying on its crown (pi. XIV, f. 1). 



Both the inner and the outer surface are covered by thin, fairly smooth and 

 continuous limiting layers, which represent the dermal and the gastral membrane. 

 Through them one sees the incurrent and excurrent cavities lying below. 



The second specimen consists of a flat plate, irregularly square, 1-2 mm. 

 thick and as large as a hand. On one side this plate thins out to form a pretty 

 straight, sharp margin which however is destitute of a spicular fringe ; one side 

 of this plate is covered. in its whole extent by a flat dermal membrane, the other 

 side is only in its thinner part thus covered by a limiting layer, here the gastral 

 membrane : in the thicker parts the mouths of the largest excurrent canals are 

 not covered, the gastral membrane extending inwards in those places and clothing 

 the walls of these excurrent canals. 



The third specimen is similar to the second. It appears as a plate of the 

 size of a rupee and has an irregular, torn margin. 



The parenchymal principal spicules are chiefly oxydiactines. These are 

 straight, 2 cm. and more long and of varying (4-40 M ) thickness. In the centre, 

 where the axial cross is situated, a slight swelling, or two or four rounded pro- 

 tuberances, are met with. The rays are pointed and towards the ends thickened, 

 club-shaped, and covered with short and thin spines. Occasionally also monactine 

 tylostyles, with a more or less clearly defined spherical terminal swelling (pi. 

 XIV, f. 5, 6), spherical silica-pearls (pi. XFV, f . 7) and stout hexactines occur. 



The long diactines are nearly all quite or nearly parallel to the outer and 

 inner surface but he at different levels and extend in all directions, crossing each 

 other at various angles. The stoutest and longest diactines are met with in the 

 vicinity of the gastral surface and there sometimes form distinct strands (pi. 

 XIV. f. 2). 



The pentactine hypodermalia are very stout and greatly contribute to the 

 strengthening of the body-wall. Their proximal, radial ray extends right down 

 to the vicinity of the gastral surface and is 1-2 mm. long accordingly. The 

 paratangential rays are only about 40-50 /* long and slightly bent inwards, 

 pretty blunt and smooth. 



Hypogastralia are entirely absent (pi. XIV, f. 2). 



The autodermalia are represented by numerous stauractines about 150 ;* long, 

 which are almost entirely covered with small, short spines (pi. XIV, f. 3, 4). 



