SALPiDiE. MOLLUSCA. Bkyozoa. 387 
small creatures is by contracting the whole body, and 
forcing the water out at one or the other extremity. 
Family II.— PELONAIADiE. 
Some other little Tunicaries have been found floating 
on the surface of the ocean, in various parts of the 
This family is composed of only one genus, Pelonaia, 
world, consisting of an ovoid-shaped body, terminated 
which contains two species, both of them very rare. 
by a long curved tail or swimming organ. They are 
The animals are simple and unattached. The test is 
minute in size, from one -sixth to one-fourth of an inch. 
more or less cartilaginous, smooth, or wrinkled, elon- 
and are rapidly propelled through the water by power- 
gated and cylindrical. The two orifices are not oppo- 
ful vibrations of the long, curved, lanceolate, caudal 
site each otlier, but are both placed on the same plant 
appendage. These form the genus Appendicularia. 
on two eminences on the anterior extremity. The 
Professor Forbes describes them as very numerous at 
creatures live buried in mud, quite unattached to anj 
times, and appearing at a little distance, “ as cloudy 
other body, and are extremely apathetic, presenting 
patches of red colouring matter in the water.” 
scarcely any appearance of motion. 
BKYOZOA. 
Before drawing our history of the sub-kingdom 
contracted, we should see the great resemblance which 
Mollusca to a conclusion, we ought to mention the fact 
a Bryozoon, such as Flmtra, has to a mollusk of the As- 
that the large group of animals formerly arranged 
cidian type. The nervous system of these little crea- 
amongst the Zoophytes, and known as the Bryozoa, 
tures is not formed on the radiated type, but consists 
are now included within it; and that their proper place 
of a single ganglion placed between the two orifices, as 
in the zoological system ought to be immediately fol- 
in the Tunicata. They have also a separate intestine. 
lowing the class Tunicata. The structure of the animals 
which possesses an anal orifice: and there exist a 
belonging to the Bryozoa is decidedly more molluscan 
gizzard-like organ and a rudimental liver. Still, as in 
than zoophytic ; and indeed were we only to imagine 
almost all systems these animals continue to form 
the minute tentacula which fringe the oral orifice of 
part of the class Zoophyta, we will postpone their 
many of the Ascidian tunicaries to be greatly prolonged 
further consideration till wc come to treat of that 
and clothed with cilia, and the respiratory cavity to be 
class. 
END OF MOLLUSCA 
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