he continuation upwards of the broad avicularia
in nearly a straight line, and their prolongation into a sharp angular
spine, on the inner side of which is a shallow cup-like cavity, whose
sides are usually more horny than calcareous. The number of fenestrae
appears to be very constant.

The length of the branches before their dividing, and their straightness,
together with the colour of this species, render it not improbable that
it is the form intended by Lamarck (l.c.).

3. C. margaritacea, n. sp.

Cellaria vesiculosa ? Lamarck.

Cells oval or sub-globular, much compressed; avicularia short and broad,
supporting a deep cup-like cavity. Fenestrae 5, large. Lower margin of
mouth notched in the middle; back of cell minutely sulcated; sulci short,
interrupted, and irregular. A small lateral area.

Habitat: Swan Island, Banks Strait.

A very beautiful species, the branches resembling strings of minute
pearls. The pearly lustre (in the dry state) owing without doubt to the
minute sulci on the backs of the cells. These sulci are not, however,
consequent upon the drying, because they are equally apparent and
constant when the specimen has been immersed in fluid. The species may
almost at once be distinguished by the notch in the lower margin of the
mouth, which notch represents the central suboral opening present in some
other species.

4. C. ventricosa, n. sp. Table 1 figure 1.

Cells oval, compressed, rather wide below; avicularia wide, supporting
sometimes a cup-like cavity, sometimes a closed broad conical spine. The
prehensile part of the avicularium itself small, seated in a deep notch
below the acuminate summit; lateral area large and well defined.
Fenestrae 7, with fissures radiating to a rounded central opening.
Anterior surface of cell studded with minute acuminate papillae;
posterior surface smooth, sometimes spotted.

Habitat: Bass Strait, 45 fathoms.

Colour dirty white or brown. Habit stiff, stem strong, straight, branches
short and crowded--probably attains a height of four or five inches. The
only other species with which it can be confounded is C. amphora, from
which it differs in the greater size and more irregular form of the
lateral processes, in the presence of the minute papillae on the surface,
and in the absence of the narrow longitudinal band on the back; instead
of which the older cells in C. ventricosa exhibit a sort of broad scutum,
almost covering the back of the cell and sending off