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.)

To which may be added, that the species are frequently coloured, red or bluish.

1.  A. neritina, Lamouroux.

Habitat:  Rio de Janeiro.  Broken Bay, New South Wales.

This species appears to be one of the most generally distributed of the
Polyzoa; it occurs in nearly every latitude in both hemispheres.

2.  A. tridentata.  Krauss.  Corall. d.  Sudsee page 3 figure 2.

Habitat:  Bass Strait (?)

This species is placed doubtfully in the Rattlesnake Collection.  It occurs, however, in Van Diemen’s Land and New Zealand (Dr. Hooker) and is abundant in South Africa.

Fam. 4.  CABEREADAE.

Polyzoarium entirely divided into ligulate dichotomous bi or multiserial branches; back nearly covered by large vibracula; avicularia sessile.

16.  CABEREA, Lamouroux.

Selbia, Gray. op.c.  Volume 2 page 292.

Cells bi-multiserial, in the latter case quincuncial.  Posterior surface of branches concealed by large vibracula, which are placed obliquely in a double row, diverging in an upward direction from the middle line, where the vibracula of either row decussate with those of the other.  Avicularia when present of the flexible kind, sessile on the front of the cell.