184 OYSTERS, AND ALL ABOUT THEM. 



second row behind ; the former are comparatively larger, 

 pearly, and ringed with jet : foot of a brilliant orange- 

 colour or white. 



SHELL nearly circular but expanding towards each side, 

 where it forms an obtuse angle, and rhomboidal behind in 

 consequence of the projection of the ears, equilateral, 

 depressed, extremely thin and rather glossy ; lower valve 

 considerably smaller than the other, and to some extent 

 enclosed within it : sculpture, fine and close-set concentric 

 lines only : colour yellowish or milk-white, mottled with 

 reddish-brown or flake-white spots or streaks, and often 

 marked by longitudinal white rays or transverse zigzag 

 lines of a vandyke pattern : margins very thin, semicircular 

 in front and sloping about halfway on each side, at an 

 angle of 45 degrees, to the beaks ; byssal slope not toothed 

 or serrate : beaks small but prominent : ears long and 

 drooping, nearly square-set, those on the byssal side being 

 the smallest, rounded at the corner ; byssal notch slight : 

 hinge-line straight, two-fifths of the breadth of the shell : 

 cartilage small : ligament so thin as to be almost impercep- 



> 



tible : hinge-plate broad and smooth ; transverse rib slight 

 and scarcely raised : inside pearly, minutely striate length- 

 wise : muscular scars distinct. Length 0*285, breadth o'3- 



HABITAT : Shetland, 95 f. F. N. U. Germany and 

 Italy. E. Loffoden L, 300 f. (Sars) ; Arcachon (Lafont) ; ! 

 Jamaica (Barrett).! Sparingly occurring, although grega- 

 rious, on all our coasts, in muddy sand, at 2-82 fathoms. 

 Glacial deposits, Fifeshire (Fleming) ; Coralline Crag (S. 

 Wood). Its distribution extends from Finmark to the 

 ^Egean, and both in northern and southern localities it 

 appears to have a considerable range of depth, viz., 15-200 

 fathoms, Upper Norway, according to McAndrew and 



