REPORT ON THE TETRACTINELLIDA. 
133 
and that Pilochrota anancora is simply a young form of Pilochrota crassispicula. 
The choanosome is similar to that of Pilochrota crassispicula, bnt the mesoderm is 
less abundantly developed. The canals are provided with thick fibrous walls, 
and numerous fusiform cells help to form the spicular tracts. Clusters of granule- 
cells, though present in the cortex (PI. XIV. figs. 21, 22), are far less numerous in the 
choanosome. The canals are provided with numerous vela, and I observed here, 
as I have in other instances, that a velum is sometimes perforated by two circular 
apertures, each surrounded by concentric myocytes. 
The flagellated chambers are aphodal, though sometimes a few appear to be eurypy- 
lous; they measure 0’0276 by 0'031 mm. in length and breadth, and the prosopyle, 
which in many cases is exceptionally clearly shown, is single and usually measures about 
0‘012 mm . in diameter. 
The sponge is of much softer texture than Pilochrota haecheli and Pilochrota 
longancora, which are hard and harsh to the touch. 
Pilochrota moseleyi, n. sp. 
Sponge compressed, ellipsoidal or thumb-shaped, attached below, bearing a single 
oscule near the summit ; oscular margin fringed with minute oxeas. Pores in sieves, 
evenly dispersed. 
Spicules. — I. Megascleres. 1. Somal oxea, fusiform, straight or curved, more or less 
sharply pointed; 1*2 by O'OIG mm., and 1'4 by 0'013 mm. 
2. Oscular oxea, small, fusiform, sharply pointed. 
3. Orthotrisene ; rhabdome conical, pointed or rounded off near the apex ; cladi conical, 
pointed, extending horizontally almost immediately after diverging from the rhabdome. 
Rhabdome 1‘6 by 0‘05 mm., cladi 0'2 mm. long. 
4. Anatrisene ; rhabdome conical, pointed or rounded off near the apex ; cladi curving 
evenly backward almost immediately past their origin, the cladome in consequence well 
rounded in front. Rhabdome 1‘6 by 0'02 mm., cladi 0*083 mm. long, chord 0*103 mm. 
sagitta 0*082 mm. 
II. Microscleres. 5. Ectosomal chiaster, a small but evident centrum, and numerous 
fine, hair-like, truncated actines ; total diameter 0*008 mm. 
6. Choanosomal chiaster, no evident centrum, actines few in number, usually from 
five to seven, slender, rod-like or somewhat conical, roughened, abruptly truncate, seldom 
tylote ; total diameter 0*024 mm. 
Colour. — Greyish-white. 
Habitat. — Torres Strait, August 7, 1874 ; depth, 3 to 11 fathoms. 
Remarlcs . — There is but a single specimen of this sponge, it measures 14 mm. in 
height, and 9 by 12 mm. in width and breadth. The single circular oscule is 2 mm. in 
