8 ' PERCY SLADEN TRUST EXPEDITION 
membrane there is a more or less strongly marked tendency to orientation with one ray 
pointing away from the osculum, and in the radial tubes there is a distinct orientation 
with one ray pointing towards the blind end of the tube. In fact the radial tubes may 
almost be said to have an articulate tubar skeleton, albeit of an ill-defined character, the 
“joints” being very confused. 
The spicules may be classified as follows :— 
(1) Triradiates of the gastral membrane (Plate 3, fig. 5, w):—These vary in form 
from regular, equiradiate and equiangular to markedly sagittal. The angles, however, 
appear always to be equal. The rays are usually long and slender, usually straight but 
sometimes a little crooked, varying greatly in length, up to about 0°27 mm. with a 
diameter of about 0°01 mm. at the base. They are sharply and gradually pointed and 
sometimes the diameter increases slightly before tapering off to the apex. 
(2) Triradiates of the radial tubes (Plate 3, fig. 5, ¢):—These are usually more or 
less markedly sagittal, owing to the greater length of the distal (basal) ray, but they 
remain equiangular. The paired rays, as usual, follow the curvature of the wall of the 
radial tube. At the blind distal ends of the radial tubes, where the spicules become much 
smaller, the sagittal character tends to disappear. The spicules in the walls of the radial 
tubes perhaps never become as large as the largest of those in the gastral membrane. 
In a triradiate from about the middle of a tube the distal ray measured about 0:12 mm. 
in length, and each of the oral rays about 0°085 mm., all with a diameter of about 
00075 mm. at the base. A triradiate from the blind end of a tube was almost equiradiate, 
with rays about 0°07 mm. in length. 
(3) Quadriradiates:—These differ from the triradiates only in the development 
of a slender and frequently crooked apical ray (Plate 3, fig. 5, e). They occur both in 
the gastral membrane (Plate 8, fig. 5, b) and in the walls of the radial tubes (Plate 3, 
fig. 5, d, e), but are much more conspicuous in the latter, where their apical rays measure 
about 0°09 mm. in length. 
There can, I think, be no question of the close relationship of this species to the 
Australian Dendya tripodifera. It ditters chiefly in the much less regular arrangement 
of the radial tubes and in the absence of the special “tripod” spicules from the distal ends 
of these tubes. 
Register No., Locality, dc. cvt. 2, Amirante Isles (Seychelles), 13.10.05, E. 16, 
39 fathoms. 
Family Leucascide Dendy (emend.). 
Sponge typically forming a massive colony, usually with several or many oscula, but 
may be integrated into a single individual with definite external form. With no large 
central gastral cavity lined by collared cells, but with an exhalant canal system devoid 
of collared cells. Flagellated chambers ranging from long, and possibly branched, with 
a tendency to radial arrangement around the larger exhalant canals, to small, approxi- 
mately spherical and irregularly scattered. With a distinct and independent dermal 
membrane (or cortex), pierced by true dermal pores. Skeleton consisting mainly of 
