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. ii. p. 407, pi. 59. f. 1, 2 ; (animal) pi. 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 fringed 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, Linnaeus. 



C. cinereus, Brit. Moll. ii. p. 402, pi. 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, being 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. 



