t rarely) an avicularium
of more moderate size on both sides. But the character of the species by
which it is more particularly distinguished consists in the presence on a
great many cells, in one part or other of the polyzoary, of the two large
and strong spines projecting BACKWARDS. This retrocession of the spines
is alone a sufficient character to distinguish the present species from
the South African form above alluded to (C. taurina, B.) And the length
and lateral position of the vittae would distinguish the unarmed cells
from those of C. elegans.

12. C. umbonata, n. sp.

Cells more or less pyriform, alate, narrow below, bulging or ventricose
upwards. Avicularia large and strong. Vittae strap-shaped, anterior,
extending from the level of the mouth to the bottom of the cell, with
elevated acuminate papillae or short spines. A broad compressed
projecting process on the middle of the back.

Habitat: Bass Strait, 45 fathoms.

The cells in this species are small, inflated or ventricose, and as it
were sub-globular above, becoming much attenuated below--but the cavity
of the cell does not appear to extend into this contracted portion, in
which is contained the connecting tube strengthened by calcareous
matter--the inferior continuation of the lateral alae, which descend from
the base of the avicularium. Owing to the large size of the avicularia,
the upper part of the cell is much widened, and the whole acquires
somewhat of a triangular form, and has a peculiar rugose aspect, derived,
in part also, from the large size and elevation of the acuminated
papillae, not only of the vittae but on the surface of the cell itself.
The central umbo or crest posteriorly is a marked feature.

c. Without vittae or fenestrae.

13. C. carinata, n. sp.

Cells oval, narrowed at both ends; lateral processes (without avicularia
?) projecting horizontally upwards from the sides of the mouth about the
middle of the cell. Mouth nearly central, with a small tooth on each
side, and below it a triangular space with three strong conical
eminences. The cell which bears the ovicell geminate.

Habitat: Bass Strait, 45 fathoms.

This remarkable form differs so widely in many respects from any of its
congeners, as almost to deserve to be considered as the type of a
distinct sub-genus. The lateral processes, which may be taken to
represent the perfect avicularia of the other species, are, as far as can
be ascertained from specimens that have b