h between the two horns
there is continued nearly, if not quite, to the inner extremity of the
organ, and along its upper border, a shallow groove, in which is lodged
the seta when in a state of rest. In most species the seta is serrated
with distant teeth on one side.

Where there are more than two rows of cells, the marginal cells differ in
conformation from the central.

As in Scrupocellaria, the opening of the cell is sometimes protected by a
pedunculate operculum. The genus, therefore, may, like that, admit of
being divided into sections, distinguished respectively by the presence
or absence of a pedunculate operculum.

a. Operculatae.

1. C. rudis, n. sp.

Multiserial; opening of cells oval, margin much thickened, with a strong
projecting upturned spine on each side in the central cells, and with
three strong and long similar spines on the outer side, and a smaller one
on the inner side in the marginal cells. Operculum spatulate, or pointed
above, entire. Each cell of the central rows with two small avicularia in
front, immediately below the mouth. Each marginal cell with a single
large vibraculum in front below the mouth. Vibracula slender, very
transparent. Setae short, not serrated.

Habitat: Bass Strait.

Colour dirty white: forms a broad frondose polyzoarium 1 1/2 to 2 inches,
or perhaps more, in height. The branches, all disposed in the same plane,
are flat, thick, and about 1/8th of an inch wide, composed of from four
to six rows of comparatively small cells, which viewed behind appear
lozenge or diamond-shaped, and arranged quincunically. It is not always
easy to observe with accuracy the outline of the vibracula, owing to the
extreme tenuity of their walls, but the groove along the upper border is
very distinct and most usually has the seta lying in it. The avicularia
on the marginal cells are very large, but not uniform in size. Along each
border of the branches runs a bundle of radical tubes, the number of
which diminishes as the branch ascends, each terminating in a vibraculum.

2. C. zelanica, Busk.

Selbia zelanica, Gray. Dieffenbach's New Zealand, volume 2 page 292.

Crisia boryi, Audouin. (Savigny Egypt plate 12 figure 4.)

Biserial; opening of cell oval or elliptical, rounded at each end,
crossed in front, and thus divided into two nearly equal parts by a
transverse calcareous band, from the lower edge of which depends a
pedunculate, falciform operculum. Cells frequently produced upwa