General History of the Marine Polyzoa. 161 
celliferous shoots, held together by a ramified stem made up of 
bundles of radical fibres given off from the inferior portion of 
the shoots ; celliferous shoots consisting of a cylindrical bi- or 
trifurcate stem, which gives origin to the radical fibres and 
also to erect chitinous rods, on the summit of which are borne 
two or three similar stems, more or less dichotomously divided. 
— Zoecia pyritorm, ranged in linear series round an imaginary 
axis, so as to form cylindrical stems; aperture moderately large, 
subterminal, oblique. Avicularia not capitate. 
I am indebted for specimens of this singular and beautiful 
form to Mr. J. Bracebridge Wilson, of Geelong, an able in- 
vestigator of the Victorian Polyzoa, and an enthusiastic and 
experienced dredger. He has kindly supplied me with a 
quantity of his dredgings,. and requested me to undertake 
the pleasant office of reporting upon any thing new which 
they may yield. As a first instalment three species, which 
seem to be undescribed, are dealt with in this paper, of which 
the present is by far the most remarkable. 
A question may arise ¢n limine, as to the systematic posi- 
tion of Rhabdozoum; and possibly it may prove to be entitled 
to rank as the type of a distinct family ; but, for the present, I 
prefer to place it among the Eucratiide, with which it has 
undoubted affinity. The zocecia bear a close resemblance, 
in many respects, to those of Hucratea chelata, Linneus ; and 
they are disposed {as in that species) in linear series, each 
cell rising from behind the top of the aperture of the one 
below it; on the other hand, the redundant spinous armature 
and the extraordinary development of the radical appendages 
are eminently Bicellarian. Avicularia are of the rarest oc- 
currence amongst the Hucratiide. The cylindrical arrange- 
ment of the cells and the rod-like pedicels on which a 
‘large portion of the celliferous stems are elevated, are distinc- 
tive characters and have no parallel in either of the two 
families referred to. 
The chitinous rods, which constitute the chief peculiarity 
of the present form, are probably a modification of the (so- 
called) radical fibres. Both these structures originate on the 
surface of the cells which compose the basal portion of the 
shoots; the fibres tend downwards and constitute first the 
compound stem or trunk of the colony, and ultimately the root- 
lets, by which the whole composite structure is held to its 
place; the rods ascend and support the principal celliferous 
segments. At its upper extremity the rod expands into a 
kind of cup, the rim of which (in the only known species) is 
set round with long spines; and from this rises a short celli- 
ferous stem, which soon bifurcates. : 
Ann. & Mag. N. Hist. Ser. 5. Vol. x. el 
