CLASS II. GASTEROPODA: OEDER 2. BRANCHIFERA. 
516 
CULATED Sea-Eak, Raliotis tuherculata, grows to a large size in intertropical seas ; it is also 
common on the coasts of the islands of Jersey and Guernsey, where it is used for food, being 
esteemed very palatable. It is well beaten to make it tender, before being cooked. The shell is 
much used for inlaying, and other ornamental purposes. 
THE FISSURELLID^. 
These are nearly related to the preceding; the shell resembles that of the limpet. The species 
are numerous and widely distributed. They inhabit rocky beds and reefs at various depths. 
The Greek Fissurella, F. Grceca, is found in the Mediterranean and the 
Indian Ocean. There are one hundred and twenty other known species 
of this genus. 
THE PATELLID^. 
This includes the Limpets, which have a conical shell, the interior of 
which is entirely occupied by the animal. They are spread over every 
latitude, except in the Arctic regions. Millions are taken every year in 
Great Britain for fish-bait, and immense numbers on the coasts of Ireland 
for food. They are foimd principally on rocky coasts,, attached to stones and shells, at a depth 
ranging from the surface of the water to thirty fathoms. They feed on sea-weed, in the masti- 
cation of which their rasp-like tongues are very efficient. They attach them- 
selves so firmly to rocks and shells, by creating a vacuum on the under sur- 
face, that they can be detached with difficulty. It is even said that they have 
the power of dissolving and absorbing the substance to which they are affixed, 
so as often to create a deep excavation beneath them. There are many species, 
varying in form and size, the largest being found on tropical shores. The Patella pecAonata is 
found in the Mediterranean. A very small species, the P. Candida, is found in our waters. On 
the western coast of South America, there is a species a foot in diameter,, and the shell is used 
by the inhabitants for a basin. Forbes tells us that each limpet has nineteen hundred and 
twenty teeth. ' ' ; 
THE GREEK FISSURELLA. 
PATELLA PECTOKATA. 
i 
THE CHITON CHILENSIS. 
THE CHITON SPINOSTJS. 
THE CHITONIDJE. 
In the Chitons the shell is composed of eight calcareous plates, overlapping one another at the 
edges, and united by a strong leathery mantle, which forms a border all round the shell. In 
some species the mantle is fringed with hair, and in others with bristles or spines. The kinds 
are numerous, and are found on nearly all rocky shores, adhering to stones and other submarine 
bodies, like the limpets ; a fcAV have the habit of creeping in the sand. More than two hun- 
dred species are known. The Chiton Chilensis has a smooth border ; it is found in crevices of" 
rocks and under stones, near Valparaiso. The Chiton spinosus is bordered by long, black, acule- 
ated spines; found in the South Seas; length three inches. Several small species are common-i 
on our coasts. 
