Cells tubular, nearly half free, divergent laterally at a right angle. Mouth looking directly outwards, border entire, slightly everted. Ovicell ---- ?
Habitat: Prince of Wales Channel, Torres Strait, parasitic upon S. pristis.
Very like the preceding in habit and size, of which it may possibly prove to be a variety. The cells, however, throughout the whole of the polypidom are of precisely the same character, in each form, and exhibit no intermediate steps. In the present species the cells are much longer, rather narrower, and the upper half is turned out abruptly at a rightangle, whilst in the former they ascend at an angle of 45 degrees, and the free portion is much shorter. The branches in both are opposite; the ovicells are unfortunately absent in each.
8. S. mutulata, n. sp.
Cells compressed or flattened, from side to side; sometimes angular, lower half adnate, upper half divergent, projecting like a bracket. Mouth looking directly upwards, narrow oblong, quadrangular. Ovicells aculeate, with strong widely set spines, pyriform depressed.
Habitat: Prince of Wales Channel, Torres Strait, 9 fathoms.
Colour light olive grey. Polypidom about three inches high, irregularly ? branched, branches not opposite. The cells are distichous, and of a very peculiar form, but varying in some degree according to their situation. The younger (?) cells on the secondary branches are flat on the inferior or outer aspect, with two angles on each side, or are quadrangular; whilst the cells on the stems or older or fertile branches are usually rounded below, or on the outer side, and thus have only one angle on each side. The mouth varies in shape according to the cell; in the former case being a regular long rectangle, whilst in the latter it is rounded on the outer side. The ovicells are placed in a single series on one side of the rachis, as in S. digitalis, but are widely different in form.
9. S. operculata, Linn.
Habitat: Swan Island, Banks Strait.
This species occurs in all parts of the world. It is to be carefully distinguished from S. bispinosa, Gray--also an Australian and New Zealand species, but which does not occur in the present collection.