250 CHITONID/. 
ductive organs; and of the other sex, we only meet with the 
doubtful oviducts, and a conspicuous well-filled ovarium in the 
genial epoch; it may therefore be inferred that these animals 
depend on their own individual generative influences. 
C. AsELLus, Chemnitz. 
C. asellus, Brit. Moll. ui. p. 407, pl. 59. f.1, 2; (animal) pl. A. A. f. 5. 
C. cinereus, Auct. 
The anatomy of this species is nearly the same as of the 
preceding, which we have considered the type of the genus, and 
as the external organs do not vary greatly, I shall only men- 
tion the deviations; the principal, and I believe the only one 
of the least consequence, is, that there are only ten branchial 
fillets on each side the body, which do not nearly occupy half 
the extent of its circumference. The inner surface of the 
mantle in different individuals exhibits the various hues of 
flesh-colour: the foot is a dull muddy purple. The margin of 
the mantle is powdered with minute, granular, dark, sand-like 
points, and frmged with very short, fine, close-set, pale yellow 
filaments. 
This species, at Exmouth, is rarely met with in the littoral 
or laminarian districts; its habitat is within the coralline 
limits, and it is scarce. 
C. cinereus, Linneus. 
C. cinereus, Brit. Moll. 1. p. 402, pl. 58. f. 1, as C. marginatus. 
C. marginatus, Auct. 
The same remarks apply to this as to the preceding species, 
from which the only decided variation is the greater number 
of branchial leaflets, bemg seventeen on each side, of a dull 
flesh-colour, and occupying considerably more than half the 
circumference of the mantle, which on its inner surface is also 
flesh-colour. A fine, setose, short, thick, pale rufous fringe 
clothes the margin of the mantle, which is minutely granu- 
lated, as if aspersed with dark sand-points. 
This very common species is strictly, at Exmouth, a littoral 
one, and rarely found beyond its limits. 
