CARDIUM. 285 



145 fathoms off the Mull of Galloway. At Guernsey 

 it is gregarious in 15-20 fathoms. Var. 1. Hebrides 

 and Shetland. Var. 2. Guernsey, 18 fathoms. The 

 typical form occurs, according to Searles Wood, in the 

 Red and Coralline Crag. Loven and many others have 

 recorded it as Scandinavian and inhabiting various 

 depths from 3 to 100 fathoms ; I have found it at Etre- 

 tat in the North of France, as well as at Spezzia ; near 

 Cherbourg (Lamarck), Gulf of Lyons (Martin), Cannes 

 (Mace), Sicily (Philippi), and Vigo (M f Andrew). 



C. nodosum has probably been passed over as the 

 young of the common cockle (C. edule}; but that species 

 is always more globular and produced in front, and has 

 much smoother ribs and less distinct and prominent 

 tubercles. The present species differs from C. fasciatum 

 in being more solid, and usually of a milk-white colour ; 

 the ribs are more thickly covered with tubercles; the 

 beaks are nearly central ; and the posterior side is not 

 obliquely produced, as in the last -mentioned species. 

 Young shells have a somewhat square outline. The 

 most brightly coloured specimens in my collection were 

 found in Guernsey, Arran Isle (Galway), and Balta 

 Sound. Southern specimens are more triangular than 

 those from the north. 



In strict justice this species ought to be called roseum, 

 being the name given by Lamarck to the second variety, 

 three years before Turton described his C. nodosum; 

 but it is now generally known by the latter name, and 

 the shell is rarely rosecolour. I before observed that 

 Montagu's shell of the same name (to which Turton 

 erroneously referred this species) is the young of C. 

 tuber culatum. The (7. roseum of Chemnitz is a Cardissa. 

 C. punctatum of Philippi (but not of Brocchi) appears to 

 be a variety of our species. 



