A small broken fragment only preserved; parasitic upon Sertularia mutulata, so that its habit cannot be satisfactorily determined.  It is of a greenish colour, but this may be adventitious, although general and uniform throughout the specimen.  This species differs from the above in being much larger, and in wanting the two perforations on each side above the mouth—­in the less comparative size of the opening of the cell, and in the remarkable elevation of the sharp margin surrounding the upper half of the cell.  In the looser aggregation, and in the form of the cells, it shows the transition from Salicornaria to Cellularia.

Fam. 2.  CELLULARIADAE.  Cells disposed in the same plane.

10.  CELLULARIA, Pallas.

Character:  (B.) Cells bi-triserial, oblong* or rhomboidal, contiguous.  Opening of cell occupying at least half of the front.  Margin thickened, sometimes spinous above.  A short spine or a sessile avicularium on the upper and outer angle.

(Footnote.  This shape of the cells is given from the back view of them.)

A. inarmatae—­without avicularium.

1.  C. monotrypa, n. sp.

Cells oblong, narrowed below, with a single perforation, in the upper and outer part behind.  Opening oval, margin smooth; a short spinous process at the upper and outer angle; a sharp short spine in the middle of the upper border of the middle cell, at a bifurcation.  Ovicell ? in form of a very shallow excavation in the upper part of the cell in front.

Habitat:  Bass Strait, 45 fathoms.

The only species with which this can be confounded, is C. peachii (Busk.  Annals of Natural History volume 7 second series page 82 plate 8 figure 1.)

The latter, however, is very much smaller, the cells narrower in proportion to their length, and the margin of the opening minutely verrucose.  The cell has more than one posterior perforation; and the central cell at a bifurcation is rounded above and without a spinous process; lastly, the ovicell is much loftier and tesselated on the surface.

11.  SCRUPOCELLARIA, Van Beneden.

Character (modified).  Cells rhomboidal, with a sinuous depression on the outer and posterior aspect.  Each furnished with a sessile avicularium at the upper and outer angle in front, and with a vibraculum placed in the sinus on the outer and lower part of the cell behind.  Opening oval, or subrotund, spinous above.  Ovicells galeriform.

This natural genus is characterised more particularly by the presence upon EACH cell of a sessile avicularium seated on, or in fact forming the upper and outer angle, and of a vibraculum placed on the back of the cell.  The cells in some species are provided with a pedunculate operculum, by which it is intended to designate a process, which arising by a short tube from the anterior wall of the cell, immediately beyond the inner margin of the opening, projects forwards and bends over the front of the cell, expanding into