Cells adnate, conical, slightly curved, truncate at bottom, narrow at top; mouth vertical, external.
Habitat: Off Cumberland Islands, 27 fathoms.
Very like a Thuiaria, but the cells are not immersed, though very closely adnate, and the outer angle of the square base of each cell is in contact with the upper and back part of the one below it, so that a small triangular space or opening is left below each cell. The branches are very regularly alternate; and the polypidom is of a light brownish colour.
(b) Cells secund.
4. S. pristis, (B.).
Idia pristis, Lamouroux.
Cells tubular, all contiguous or adnate to each other, and to the rachis, upper half curved laterally, lower half closely adnate, almost immersed in the rachis; mouth looking upwards, rounded, expanded, almost infundibuliform, border slightly scalloped towards the rachis, and projecting externally. Ovicell cyathiform, long narrow with circular rugae. Mouth as large as the diameter of the cup, margin very slightly everted.
Habitat: Prince of Wales Channel, Torres Strait, 9 fathoms. Off Cumberland Islands, in 27 fathoms, fine grey mud.
I see no reason why the present species should not come under Sertularia. It is peculiar from the position and extreme contiguity of the alternate cells. The ovicells arise from the back of the rachis towards the side. When viewed posteriorly, the cells are seen through the transparent rachis, and it might thus at first sight appear as if the rachis itself were cellular and not tubular, but such is not the case. The tube is wide and continuous from end to end.
2. Cells opposite (sometimes alternate on the stem). (Dynamena).