VARIETIES OF OYSTERS. 173 



The animal of the adult scallop, when at rest, is a 

 study for a painter, with its large and bright pink ovary, 

 and its mantle studded on each side with a row of brilliant 

 eyelets, like dew-drops glittering in the sun of a May 

 morning. The transverse plates form hollow or vaulted 

 scales in young shells, and their surface is minutely and 

 closely tuberculed, like the cells of Polyzoa. In the fry 

 the upper valve is much larger than the lower one, and 

 overlaps it. The ribs are not then formed, but the byssal 

 sinus is well developed. Specimens from the Firth of 

 Forth and Shetland are much larger than usual, although 

 slightly differing from each other in their relative pro- 

 portions Occasional distortions or monstrosi- 

 ties occur. P. opercularis may be readily known from either 

 of the two foregoing species by its circular form, greater 

 size, and nearly equal ears. The P. Audouinii of Payrau- 

 deau can hardly be considered a variety. Its sculpture is 

 that of the P. lineaius of Da Costa, and only differs from 

 that of ordinary specimens in the scales being more regular 

 and continued across the ribs. The P. subrufus of Turton 

 is merely the young state, with a straighter outline. Many 

 other specific names have been invented by authors, for 

 still more trifling varieties. 



4. P. SEPTEMRADIATUS, Miiller. 



P. septeniradiatus, Mull. Zool. Dan. Prodr., p. 248, No. 2992. 

 P. Danicus, F. and H. 2, p. 288, pi. 52, f, 1-2, 7-10. 



BODY whitish, tinged with fleshcolour, and minutely 

 speckled with flake-white ; the colour is also diversified by 

 blotches and streaks of dark brown, orange, yellow, or 

 greenish : mantle thick, folded inwards on each side ; the 

 margin is fringed with numerous cirri or tentacles, which 



O O 



are closely and finely ciliated ; they are of different sizes, 



