ricius.

1. Cellepora bilabiata, n. sp. ?

C. labiata, Lamouroux.

Cells deeply immersed; mouths in some entire and unarmed; in others, with
two acuminated conical lips; immediately beneath the apex of the
posterior lip a small sessile avicularium. Ovicells subglobular, with a
scutiform area on the upper surface, marked with several lines on each
side, radiating from a central line.

Habitat: Bass Strait.

Parasitic on several zoophytes. This species to the naked eye exactly
resembles C. pumicosa, but on closer examination several important
differences will be observable. The cells in C. bilabiata are less
rounded and less distinct than in C. pumicosa. As in that species, some
of the cells are furnished with an avicularium, and others unprovided
with that appendage; and again, some cells support an ovicell, whilst
others do not. The mouth of the unarmed cells in both species is more or
less circular and plain, but in C. bilabiata, even in the unarmed cells,
the mouth is occasionally distinctly bilabiate. In C. pumicosa the
avicularium is placed subapically on a solitary posterior obtuse mucro,
but in C. bilabiata there are two such processes longer and more pointed,
one in front and the other behind the mouth; the avicularium, as in the
former case, being placed immediately below the apex of the posterior
mucro. The ovicells also differ very much. In C. pumicosa this organ
presents several rather large circular spots or perforations ? whilst in
C. bilabiata it exhibits a scutiform or horseshoe-shaped area, marked
with several transverse lines on each side of a middle longitudinal line.

Fam. 7. GEMELLARIADAE.

Cells opposite, in pairs.

22. DIDYMIA, n. gen. Table 1 figure 6.

Cells joined side by side; opening large, oval; mouth subapical, central.
No avicularium. Ovicells contained within a cell, which is central at
each bifurcation.

1. Didymia simplex, n. sp. Table 1 figure 6.

Cells oblong, narrowed below, broad and truncate, with an angle
externally above. Back marked with transverse rugae.

Habitat: Bass Strait, 45 fathoms.

A fine species, growing in loosely-branched phytoid fronds, to a height
of several inches. In some (dried) specimens the branches are a little
incurved, but not in all. The situation of the ovicell is peculiar. It is
contained within the upper part of a cell placed between, or rather in
front of the pair, from which the two branches at a bifurcation take
their origin. The ovig