nt of the cell, expanding into a variously-formed limb, and serving as
protection to the mouth of the cell in front. The cavity of the tube by
which the process arises, becomes, in the expanded portion, continuous
with variously disposed grooves or channels, which terminate at the edges
of the operculum. This organ affords excellent specific characters (not
in this genus alone). Besides the sessile avicularia above noticed, many
species of this genus also possess avicularia of another kind, and which
are placed on the front of the cell below the opening and towards the
inner side, or in other words, towards the middle line of the branch. In
this genus, in all those species in which the second avicularium occurs,
each individual cell is provided with one. This additional avicularium
appears to be composed of a flexible material, and it is very easily
broken off, so that in many instances, perhaps throughout an entire
specimen the organ itself may be wanting, although its position is
clearly evidenced by the existence of a rounded opening in the usual
situation of the organ. It is necessary to distinguish this form of
flexible (if such it be) avicularium from the truly articulated and
movable avicularia, in the form of birds' heads, and which form does not
occur in the genus Scrupocellaria.

a. OPERCULATAE. Cells furnished with a pedunculate operculum.

1. S. cervicornis, n. sp.

Veins or channels in the oral operculum, branching so as to resemble the
antlers of a stag. The marginal spine next above the pedunculated
operculum, bifurcate.

Habitat: Off Cumberland Islands, 25 fathoms, fine grey mud.

A small, delicate, parasitic species, very transparent. The very peculiar
markings on the operculum at once distinguish it. The upper margin of the
mouth is furnished with five elongated spines, the innermost of which is
forked at the extremity.

2. S. diadema, n. sp.

Cells elongate, external side nearly straight, vibraculum sublateral,
very prominent. Limit of operculum entire, or obscurely bi-trilobed. A
flexible avicularium in front. Ovicell usually with a single row of four
or five openings immediately above its mouth.

Habitat: Moreton Bay.

b. INOPERCULATAE. Cells without a pedunculate operculum.

3. S. cyclostoma, n. sp.

Opening of cell nearly or quite circular, margin much thickened, with
three or four short indistinct spines above. Vibraculum sublateral. A
flexible avicularium in front. Ovicells --- ?