218 CHITONID.E. 



species resemble punctures, and produce a latticed ap- 

 pearance. 



It is the C. albus of Pulteney and Montagu (but not 

 of Linne), C. alveolus of Sars, and probably C. tubercu- 

 latus of Leaches *" Mollusca of Great Britain/ 



5. C. cine'reus^, Linne. 



C. cinerea, Linn. S. N. p. 1107. C. asellus, F. & H. ii, p. 407, pi. lix. 

 f. 1, 2, and (animal) pi. A A. f. 5. 



Body broadly oval, brownisb-yeUow, orange, or of a some- 

 what tawny flesheolour : mantle thin : girdle rather narrow, 

 covered with small oval, rather shiny, yeUowish-white or 

 darker-coloured granides, which he one upon another in a thick 

 heap ; margin closely fringed with sharp whitish spines : head 

 semicircular, surrounded by a narrow hood : mouth fonning 

 when at rest a transverse and concentrically wrinkled sht ; but 

 when open and showing the teeth, it becomes circular : giUs 

 pale brownish -yellow ; only from 6 to 10 of the plumes or 

 leaflets nearest the tail, on either side are visible, the others 

 being convoluted and withdrawn : foot oval, broader in front, 

 and margined by a pinkish line : vent short and tubular. 



Shell compressed : plates as in C. canceJlatus, but less solid 

 in proportion to the size ; lateral compartments indistinct : 

 scidpture similar to that of the last species, although much 

 finer and never exhibiting a punctured or cancellated appear- 

 ance : ridge sHght, more or less conspicuous : colour pale yel- 

 lowish, often irregularly streaked lengthwise with dark lines, 

 and sometimes having a transverse mark of the same hue on 

 the lateral compartment near the beak in each plate: heal-s 

 small: inside porceUanous, streaked in the middle hke the 

 outside, displaying the leaf-like shoulders described in C. can- 

 cellatus ; margin not notched, but crenulated in the same way 

 as in the last two species. L. 0-5. B. 0-35. 



Yar. Rissoi. Shell of a uniform pale yellowish colour. 

 C. Bissoi, Payraudeau, MoU. Cors. p. 87, pi. iii. f. 3, 4. 



Habitat : Stones, and old shells (especially oysters) , 

 everywhere in the laminarian, coralline, and deep-sea 



* Ash-coloured. 



