FLOOR.] EASTERN ZOOLOGICAL GALLERY. 
17 
which (the T. gigas), when fall grown, is the largest and heaviest of 
shells, some of them weighing more than 300 pounds. The Phola- 
daeea, or Boring shells, live sunk perpendicularly in holes in rocks, or 
in sand. Tables 39-48 contain the Asiphonophora, which have the 
mantle-leaves free, and sometimes a separate single siphonal opening, 
for the emission of the water, as the Mussels and Oysters, many of 
which secrete pearls ; the brightly-coloured Spondyli, or " Thorny 
Oysters," with their rough, foliated or spiny shells, and the thin 
Placunse, or " Cake-Oysters," which are semi-transparent. 
In Table 49-50 are shells of the MoUusca which have no distinct 
foot on the under side of the body, and which either live attached to 
marine bodies [Brachiopoda], or float on the surface of the sea (Ptero- 
poda), or walk on their heads [Cephalopoda). The Pteropoda have an 
expanded fin on each side of the small foot. Of these the Limacina and 
Clio are so abundant in the Arctic Seas as to form a great part of the 
food of the whale. The animals of Cephalopoda (of which the Cuttle- 
fish is an example) have eight, ten, or many strong and elongated 
arms round the mouth of their large and distinct head, on which they 
crawl : the mouth is armed with large beak-like jaws. Their eyes are 
large, and their back is generally supported with a horny blade, some- 
times strengthened with a shelly coat, as the cuttle bone. They have 
a secretion of a deep black colour, which they emit when in danger, 
and thus conceal themselves. They are very voracious creatures. 
The female of the Paper Nautilus (Argonauta) fabricates a delicate 
symmetrical shell, in which she lays her eggs, and thus protects them. 
Both sexes of the Pearly Nautilus form a shell for their protection, 
one portion of which is divided into chambers. Some of the extinct 
chambered shells, as the Ammonite, are placed with the Nautilus 
Shell in Table 50. 
In some of the side Table Cases there are — a series of specimens ex- 
hibiting the structures, diseases, deformities, and reparations of shells, 
such as the distorted variety of the common Garden Snail, described as 
Helix cornucopice ; a series of the eggs and egg-cases of Molluscs; a 
series of specimens exhibiting the shells used for commercial purposes, 
such as the cameos, mother-of-pearl, gloves made from the byssus of 
the Pinna, the Chank shells carved by the natives of India and used 
in their temples. In another Case are specimens of the various kinds 
of Sea Slugs (Holothurice) ; in China and the East Indian Archi- 
pelago they are sold as articles of food, under the name of ,Tre- 
pang. 
Some of the rarest examples of small quadrupeds are exhibited on 
the Table Cases. The stuffed specimen of the Aye-aye of Madagascar 
shows its large ears, the slender middle finger of the fore-hand, and 
the thick thumb of the hind-hand. The skeleton of the same animal 
shows the strong curved chisel-shaped front teeth : w4th these the 
Aye-aye gnaws down to the burrows of wood-eating grubs, and with 
its slender hooked finger extracts them. It is nocturnal, arboreal, 
and is guided to its favourite food by its acute sense of hearing. Also 
the curious Chlamydophorus and its singularly formed skeleton from 
