REPOKT ON THE TETRACTINELLIDA. 
23 
and deeply staining, but it is not simply a granular mass, but a complex of discrete parts, 
each of which in a manner simulates the structure of a cell. Thus in many cases we may 
readily discern fine darkly-stained fibrils radiating through the protoplasm towards the 
periphery of the cell, and in fortunate cases these can be traced in continuity with small 
columnar or stellate bodies, within which an oval vesicular space containing a small deeply 
stained granule can be distinguished. In other cases oval vesicles with a distinct wall, and 
not merely vesicular spaces, can be distinguished, and within these granular material with 
one granule larger than the rest is to be seen. In fig. 21, PI. IV., numerous columnar 
pseudocells are shown with their bases adjacent to the nucleus and their filamentous 
extremities directed peripherally. The structures shown in this figure are those which it 
was found possible to trace with a camera ; the rest of the cell left blank presented 
similar appearances, but hardly sharply defined enough to be traced. Small deeply stained 
amoeboid cells, about 0’03 mm. in diameter, also occur in the ehoanosome, and appear to 
be young forms of the cells just described. If so, the latter are in all probability ova. 
Parasitism. — 1. Ophiurids. Each cloaca in all four specimens of the sponge 
harbours an individual belonging to some species of Ophiurid. This Ophiurid, though 
small compared with some other species, is large compared with the size of the cloaca, 
which it nearly fills. Its disc is 5 mm. in diameter, and its arms when uncoiled 45 mm. 
long ; they are recurved over the aboral surface of the disc, leaving the mouth exposed 
and the teeth projecting. Its position within the cloaca is rather to one side of it, 
within a faintly marked recess. The oscule of the chamber is large enough to allow of 
the egress of the tenant, but the rat-trap-like arrangement of the fringing spicules would 
seem to preclude return, and, as the Ophiurid does not feed on the sponge itself, it 
becomes a curious problem to discover by what means it obtains its food. 
2. Worms. Numerous encysted worm-like parasites in various stages of development 
are common on the ehoanosome. 
Cinacliyra^ n. gen. 
The cortex is not excavated by subdermal cavities ; oxeate spicules traverse it 
radiately. The incurrent and exeurrent openings are confined to special flask-shaped 
recesses. The mesoderm of the ehoanosome is a collenchyma ; the chamber system 
is eurypylous. 
Cinachyra harhata, SoUas (Pis. III., XXXIX.). 
Cinacliyra barhata, Sollas, Prelim. Account, Sci. Proc. Roy. Dubl. Soc., vol. v. p. 183, 1886. 
Sponge (PL III. fig. 1) a subspherical or subcylindrical body seated on a dense mass 
of tangled spicules, Oscules large and numerous, with a conspicuous sphinetral margin, 
1 Ktv-»/(.vpot, > 1 , a kind of bag or sieve for bolting flour. 
