Cells much elongated outwards, horizontal or projecting portion oblong, rounded at the extremity; 2 to 5 long curved submarginal spines, externally a single dorsal spine about halfway down the cell; opening oval, narrower outwards; very oblique mouth at the outer end. Avicularia ---- ?
Habitat: Bass Strait, 45 fathoms.
Quite distinct from B. ciliata not only in its size, which is nearly three times as great, but in the form of the cell and the opening. The number of spines varies very much, and two or three of them, not unfrequently, arise from a common projecting process or base.
4. B. johnstoniae.
Cells obliquely truncated above with a short spine on the outer angle; opening large, suboval, with an obtuse angle outwardly; margin slightly thickened, wholly unarmed.
Habitat: Off Cumberland Islands, 27 fathoms, fine grey mud.
Of a light grey colour: grows in large loose tufts, composed of long forked ascending branches. It is a very peculiar species, and some difficulty has been found in finding it a place. In the opening of the mouth, and the external short spine, it is a Cellaria; and in the colour and want of distinct articulation, it approaches Acamarchis; whilst in the form of the cell, and their mode of mutual connection, it is a Bicellaria: it differs from all other species of that genus, however, in the absence of any long spines, and in general habit. Were it not referred to that genus, it would probably constitute the type of a distinct one. A curious little trident-like organ is visible in the narrow part of some cells.
15. ACAMARCHIS, Lamouroux.
Character. (B.) Cells elliptical,* closely contiguous; opening very large, margin simple, not thickened. Avicularia not always present, like birds' heads.
(*Footnote. Viewed posteriorly.)