remarkable Species of Cliona. 59 
the open end of those diaphragms that are perforated, a thin 
film of dried protoplasm or structureless membrane extends 
(Pl. I. fig. 10, 7), with a small central or excentric lumen 
(fig. 10, 2). In the membranous film a few spicules are 
usually present. 
There can be no doubt as to the attachment of the dia- 
phragms ; for on removing one from its chamber it often leaves 
behind it a row of adherent spicules. 
On examining the interior of the chambers of the Cliona 
one finds its body-spicules lying full length against the walls, 
without any tendency to a regular arrangement; one also 
finds fragments of structureless membrane adhering loosely to 
the walls, or lying freely in the interior of the chambers, and 
in these each of the different spicules of the species are con- 
tained. Small rounded granular bodies (Pl. I. fig. 12, c, and 
fig. 18) also occur rather plentifully in these bits of mem- 
brane; and since they sometimes contain vacuoles (fig. 18, d), 
we may regard them as desiccated cells. 
The walls themselves are pitted all over with hemispherical 
excavations (fig. 8) having rounded edges, and usually about 
0-001 inch in diameter. These, which are usual, I suppose 
to be the first results of the solution by which the Cliona 
excavates its abode. 
Little circular openings (PI. I. fig. 16) are also visible on 
the sides of the chambers, and become much more clearly 
exposed after washing the chambers with a little dilute acid ; 
they lead into tubular processes of variable length, generally 
simple, sometimes bifurcating, and apparently terminating 
blindly. / 
On the outside of the Jsts containing the Cliona may be 
seen a number of rounded holes (PI. I. fig. 17), by which the 
chambers with which they communicate freely open to the 
exterior. ‘These holes are not very abundant; indeed I have 
been surprised not to find more of them. ‘They occur in 
groups, and appear to be of two kinds—one larger (fig. 17, 0), 
serving probably for the oscules of the sponge, and the other 
smaller, for its pores (fig. 17, p). Generally in the Clionide 
they present a crown of pin-like spicules pointed outwardly. 
On dissolving a fragment of the infested Js7s in acid we 
liberate the spicules it “contains, and then find not only the 
forms we have already described, but a number of others of 
quite a different character, particularly the abundant sword- 
like forms, of which instances are exhibited in Pl. IL. figs. 
10,11. At first I thought these were proper to our species 
C. mucronata ; and since ‘they appeared to be more numerous 
- in its chambers than the mucronate forms, I set them down as 
