This genus was so called from the resemblance of its testaceous covering
to a coat of mail. The form of the Chiton is very similar to a
well-known insect called the woodlouse, found in decayed timber; it
generally adheres to rocks, or lies rolled up like a ball among seaweed
and stones. In length it seldom exceeds an inch, except in tropical
climates, where they are sometimes three or four inches long. In general
there are eight valves, the termination of which is surrounded by a
scaly or rough ligament, which enables the animal to expand or contract
its shell freely. It presents a great variety of colour; in general it
is dark brown, overcast with a shade of green, but some are beautifully
variegated with pink, yellow, blue, or red; interior green or whitish.
Shell more or less elongated, consisting of a longitudinal series of
eight very symmetrical calcareous pieces, more or less curved, and round
at both extremities; summit more or less marked, and when imbricated,
always from front to rear.
Chiton gigas.
C. squamosus.
C. Peruvianus.
C. spinosus.
C. fascicularis.
C. marginatus.
_C. squamosus._ The scaly Chiton. Pl. 1, fig. 1.
Depressed, valves large, carinated, well imbricated; the interstices
offering well-marked lateral spaces; the border of the mantle regularly
scaly.
_C. marginatus._ The marginated Chiton. Pl. 1, fig. 2.
Valves carinated and projecting over each other; finely shagreened, with
a dusky reddish-brown margin.
_C. fascicularis._ The fasciculated Chiton. Pl. 1, fig. 3.
Valves more narrow, imbricated, without distinct spaces; lateral parts
of the skin naked or hairy, but always provided with silky or hairy
tufts disposed in pairs between the junctions of the valve.
_C. spinosus._ The spiny Chiton. Pl. 1, fig. 4.
Shell beset with long, thin, curved, tubular, hairy, blackish spines.