VARIETIES OF OYSTERS. 175 



species: muscular scars rather distinct. Length 1*625, 

 breadth 1*475. 



Var. i, alba. Shell of a milk-white colour. 



Var. 2, Dumasii. BODY greyish, irregularly streaked 

 lengthwise with dark brown and red, and closely speckled 

 with yellowish-white : mantle thick and folded inwards ; 

 edges marked with a dark line, and thickly covered with 

 pointed cirri of various lengths and sizes, which are finely 

 ciliated ; the longer ones are very extensile, and some- 

 times curl and unfold to a length equal to half that of the 

 shell : ocelli numerous, placed more close together at the 

 sides than in front, where they are alternately large and 

 small ; they look like globules of quicksilver, or glistening 

 pearls, or white coral beads set in rings of dark bronze : 

 *foot finger-shaped, byssiferous, issuing from the notch on 

 the posterior side below the large ears of the shell ; it is 

 of a pale orange-colour. The animal occasionally uses its 

 foot for crawling. 



This variety is connected with the type by several 

 intermediate forms, as regards both the shell and the soft 

 parts. 



SHELL smaller and more solid, longer in proportion 

 to its breadth ; upper valve less convex than the lower 

 one, and sometimes quite flat or even slightly concave : 

 sculpture coarse, with 3-10 sharp ribs: ears often unequal, 

 those on the byssal side smaller than the opposite pair. 

 P. Dumasii, Payr. Cat. Moll. Corse., p. 75, pi. 2, f. 6, 7. 



HABITAT : F. Ireland and Italy. E. Loffoden I., 300 

 f. (Sars). Rather plentiful in Loch Fyne, and generally 

 distributed over our northern seas, and southward as far as 

 the Northumberland coast, in 20-90 fathoms, rough 



