N. ZOOL. GAL.] 
NATURAL HISTORY. 
97 
THE NORTHERN ZOOLOGICAL GALLERY. 
FIRST ROOM. 
This Room may be considered as an appendage to the two foregoing. 
The Wall Cases contain a series of the skulls of the larger Mammalia, 
to illustrate the characters of the families and genera, and of the nests 
of birds, and the arbours of the two species of Bower-birds, the one or¬ 
namented with fresh water shells and bones, and the other w ith feathers, 
land-shells, &c. The Table Cases contain the tubes of annulose animals, 
and the casts of the interior cavities of shells and various specimens of 
shells, illustrative of the diseases and malformations of those animals. 
The first Table Case contains the hard cases of the Annulose Ani¬ 
mals which are destitute of jointed feet, and are only provided with 
bristles to assist them in moving from place to place. The species arc 
very numerous, as may be seen by the specimens kept in spirits in the 
Fifth Room of this Gallery, but only a few of them, as the Amphi- 
trite and the Serpula , have cases for their protection. The cases of 
the Amphitrites only consist of a membranaceous tube, which being 
deposited in a fluid state, attaches the stones, sand, and other neigh¬ 
bouring bodies to its outer surface. These bodies add to the strength 
of the tube, and also assist in concealing the animal from fishes and 
othqr rapacious animals. It is doubtless for the same reason that the 
larvae of the Caddis Fly found in ponds make cases of a somewhat 
similar structure. The cases of the Serpula and allied genera are 
hard, like shells, and formed in the same manner by the deposition of 
a quantity of animal matter mixed with a chalky secretion, proceeding 
from the glands on the surface of the animal. As the animal enlarges 
in growth, and requires a larger case for its protection, it continually 
adds new layers of this matter near the end of the shell where its head 
is placed, and drawing its enlarged body forwards, gradually increases 
the size of the tube to fit it to the body, on wdiich it is, as it were, 
moulded, and thus the tube assumes a tapering form. It is difficult to 
distinguish the tubes of some of these animals from the tubular shells 
of Mollusca, such as Vermetus , Magilus , &c., (some species of which 
Lamarck confounded w 7 ith them,) unless the animal can be examined; 
but there is always one difference, that the animals of Mollusca are 
invariably attached to their shell by a strong muscle, and never quit it 
except at their death, w r hile the Annelides only use it as a place of re¬ 
treat, are not in any way attached to their shells, and often leave and 
form fresh ones, as occasion may require. 
These animals are generally provided with an appendage on the side 
of the head, which bears on its end a calcareous operculum, used to 
close the mouth of the tube when the animal is contracted into it. The 
opercuta vary greatly in shape in the different genera, and sometimes 
even in the individuals of the same species in the same group of shells. 
Turton described the operculum of one of the British species under the 
name of Patella tricornis. The operculum of the New Holland genus, 
Galeolaria , is very complicated, and furnished with a series of reflexed 
plates on the edge. 
In Cases 3 and 4 are exhibited a series of shells exhibiting the more 
prominent points in the economy of Mollusca, as— 
F 
