CHAPTER XII. 
Moss-Animals and Lamp-Shells,— Subkingdom MOLLUSCOIDEA. 
The exact positions in the animal kingdom of the Bryozoa or moss-animals, and 
the Brachiopoda or arm-footed animals, which are generally united under the name 
of Molluscoidea, is still far from settled. The Brachiopods were long placed with 
the Molluscs, and the Bryozoa with the Corals and Sponges; but fuller knowledge 
made it evident that the Biyozoa did not in any way belong to the latter. Next, 
they were classed with the Rotifers, or wheel animalcules, under the name of 
Ciliata, as a kind of appendage to the worms, while by others they were grouped 
with the Ascidians. They are here placed with the Brachiopoda, not because the 
two groups are really related, but simply because they are alike in having no 
established place in the classification of the animal kingdom. It is true that the 
Bryozoans and the Brachiopods are sometimes classed together because of the 
similarity of their development, and also for certain supposed anatomical resem¬ 
blances between them; but these latter are far from convincing, and the similarity 
of their larval histories has been disputed. 
Moss-Animals,— Class Bryozoa. 
The moss-animals almost always live in colonies, the individuals of which are 
joined in a number of different ways to form stocks. The individual animals are small, 
and the stocks generally also small, never forming anything approaching the masses 
of substance yielded by those of the corals. The structure of the Bryozoan animal can 
be studied in the accompanying figure, which shows, greatly magnified, the external 
outline and the inner organs of a single individual belonging to the stock of a fresh¬ 
water form ( Paludicella ) from Belgium. The individual figured has been detached 
at its base from the one below it, and the one next above is broken off. The body is 
represented by a chamber or cell, in this case somewhat elongated. Its walls are stiff, 
except at the anterior end, where they are flexible enough to allow the crown of ten¬ 
tacles (a) to be protruded as in the figure, or to be withdrawn by means of muscles 
(m). One of these muscles is seen to be specially powerful, and runs through nearly the 
whole length of the cell. The mouth is at the anterior end of the body, surrounded 
by the circle of ciliated feelers or tentacles (a). The alimentary canal, which com¬ 
mences with a muscular pharynx (b) hangs down in the form of a loop into the 
body-cavity, the stomach ( g) being its lowest portion. Its terminal portion runs 
again towards the anterior end, so as to open not far from the mouth (at c). The 
whole alimentary tube is but loosely fastened to the body-wall, its chief attach¬ 
ment being by means of a single short strand at the end of the stomach called the 
funiculus, and shown in the illustration. In all adults, two masses of cells are 
