EEPORT ON THE TETRACTINELLIDA. 
131 
surrounding protoplasm of the exterior of the cell, appearing as a pale circular area 
within a darkly stained granular field, bounded by a polygonal margin. In one instance, 
instead of a young aster, two minute siliceous globules were observed within the 
spicule cell. Fibrous strands are frequently seen wandering irregularly through the 
sarcenchyma. 
The flagellated chambers vary from about 0'0197 by 0’0237 mm. to 0'0237 by 
0'0276 mm. in length and breadth. 
The structure of the fibrous bands by which foreign objects are attached to the 
sponge is similar to that described under this head in Pilochrota gigas. 
Pilochrota purpurea, var. longancora, Sollas (PI. XIV. fig. 37). 
Pilochrota longancora, Sollas, Prelim. Account, Sci. Proc. Roy. Dubl. Soc., vol. v. p. 190, 1886. 
Sponge, small, somewhat quadrangular, cushion-shaped, with rounded margins ; free. 
A single circular oscule on the upper ^rface, in the centre of a circular periproctal 
membrane or cloacal roof. Margin of the oscule minutely fimbriated by a short fringe 
of minute oxeas projecting radiately in the plane of the aperture. Surface of the 
sponge rough, uneven ; pores lying in irregular winding channels or pits, separated by 
irregular spicular ridges and pillars. 
Spicules. — I. Megascleres. 1. Oxea, fusiform, straight, or more usually slightly 
curved; sharply, but sometimes abruptly pointed ; l'63by0’035 mm. 
2. Orthotrieene ; rhabdome conical, sharply pointed, with simple cladi, projecting at 
first outwards and forwards, but curving into horizontality toward the end. Rhabdome 
2T by 0’047 mm., cladi 0'35 mm. long. 
3. Anatrisene; rhabdome long, slender, conical, sharply pointed, but sometimes 
rounded off at the end ; cladi conical, making a large angle with the rhabdome, and only 
slightly recurved. Rhabdome 3'5 by 0'0237 mm., cladi 0’075 mm. long, sagitta 0‘048 
to 0’06 mm.; chord from 0T27 to 0T4 mm. 
4. Oxea of the oscular membrane, minute. 
II. Microsclere. 5. Chiaster, 0'009 mm. in diameter in the ectosome, increasing to 
0'012 mm. in the choanosome. 
Colour. — Ashen-grey ; the choanosome of a brownish- white tint. 
Habitat. — Torres Strait, August 1874 ; depth, 3 to 11 fathoms. 
Remarks. — This sponge is almost identical with Stelletta purpurea, Ridley, being 
chiefly distinguished by the much greater length of the anatrisene. There is but one 
specimen in the collection; it measures 20 by 15 mm. in length and breadth, and 11 mm., 
in height. The circular oscule is 1'5 mm., and the surrounding membrane 3 mm. in 
diameter. 
