364 THE BIRDS-HEAD CORALLINE. 
decomposing animal substance in water invariably attracts crowds of infusory animalcules, 
which then breed with amazing rapidity, so as to form a cloud of living atoms around the 
decaying body, quite invisible in the aggregate to the unassisted eye ; and these remain in the 
vicinity, playing round and round until the organic matter is quite consumed. Now, a tiny 
annelid or other animal caught by the bird’s head of a polyzoon and tightly held, would 
presently die; and though in its own substance if would not yield any nutriment to the 
capturer, yet by becoming the centre of a crowd of busy intusoria, multitudes of which would 
constantly be drawn into the tentaculean vortex and swallowed, it would be ancillary to its 
support, and the organ in question would thus play no unimportant part in the economy of 
the animal.”’ 
We now proceed to the vibraculum. It is hollow, the interior being filled, during the life 
of the animal, by a fibrous contractile substance, which enables the organ to perform its 
curious movements. These movements are very irregular as regards time, but very regular in 
their directions, each vibraculum sweeping slowly over the whole surface within its reach, first 
moving in one direction and then in the other, and it is sufficiently notable that these move- 
ments will continue for several days after the death of the polype to which it is attached. 
The mouth of a cell belonging to another polyzoon shows a curious operculum, with a 
branched form, like the horn of a fallow deer, and may be contrasted with the simple spiny 
operculum. 
IT am now going to describe several curious and bizarre forms of Marine Polyzoa. One of 
them is the Bull’s-horn Coralline of Ellis—the Ladies’ Slipper, as it is more elegantly and 
equally appropriately named at the present day. The cells of this species bear a considerable 
resemblance to a series of delicate, slender-toed slippers, adherent to each other, while from 
the opening protrudes the beautiful bell-shaped circle of tentacles. Sometimes a rudimentary 
cell may be found, but always below the aperture. 
A common creature is the Snake-head Coralline, so called from the extraordinary simili- 
tude with a, reptile. 
In another species, which is called Bednia mirabilis, the mouth is surrounded with a 
series of thorns or spines. It is found mostly on shells. Each cell is united to its pre- 
decessor and successor by a slender tube. 
The curious Farciminaria, remarkable for the array of short and stout spines with which 
its surface is thickly studded, is a New Zealand species, and appears to be the sole representa- 
tive of its family. It grows in slender branches, which are dichotomous. 
In the family to which the Gemellaria loricdta belongs, the cells are arranged in pairs and 
opposite each other, the orifices of the pairs looking in the same direction. This species is the 
Coat-of-Mail Corailine of Ellis, deriving its name from the shape of the cells, which bear no 
slight resemblance to steel corslets. 
The succeeding family, of which the Dimetépia spicata is an example, may be known by 
the arrangement of the cells, which are in pairs, but with their mouths placed at right angles 
to each other. When growing, it is a very pretty species, being white, nearly transparent, 
and attaining a height of about three inches. It grows in thick tufts, and is found in Bass’s 
Straits. 
The Shepherd’s-purse Coralline of Ellis (Wotamia bursaria) is a common European 
species, and its peculiar avicularium shows a tobacco-pipe-like head. 
A most curious vibraculum, which is toothed like a saw, belongs to a creature called 
Caberéa patagonica, living in the country from which it takes its specific name. 
On avery remarkable species, the Bicellaria ciliata, the cells are surrounded by long 
processes. An avicularium belonging to another species of the same genus is conspicuous for 
the enormously long stalk of the head, and the three finger-like appendages at the base. 
A tolerably common European species is the Bird’s-head Coralline (Bigula avicularia), 
popularly so called on account of the number, shape, and activity of the avicularia. Our 
attention is now called to a well-known polyzoa, which may be found lining the sides of rock- 
pools, or affixed to shells, and even to living crustaceans, the spider-crab being often enveloped 
