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.
4. Patella. The Limpet or Dishlike Shell. Forty-five species.
The Patella of Linnæus was divided by Lamarck into several distinct genera, and now comprehends only such shells as are of a conical form, with an imperforated summit. The anterior is that part to which the summit inclines, and is always more narrow than the posterior part.
It derives its name from its resemblance to a little dish; the colour and structure are various; some are smooth, others granulated, and many are covered with elevated tuberculated ribs. The exterior is sometimes of a pale fawn colour, and the interior of a bright pink; some have a silvery hue, but the more general colour is bluish white or light brown.