CORBULA. 57 



growth ; it is contained in a cavity or depression of the car- 

 dinal tooth in the left valve: hinge-liae obtusely angular: 

 hinge-plate rather broad and strong : teeth, in the right valve a 

 thick, pyramidal, and recurved cardinal, besides a long ridge- 

 like lateral on each side ; in the left valve a thick cardinal, 

 which resembles in shape the bowl of a spoon, and may be 

 considered the cartilage-pit, altliough it is not horizontal and 

 it slopes upwards from the beak ; close to it on the anterior 

 side of the same valve is a cavity for the reception of the oppo- 

 site tooth : inside porcellanous and glossy, microscopically and 

 closely wrinkled, more or less stained with coffeecolour ; edges 

 somewhat bevelled : pallial scar slight, with an extremely 

 shallow sinus : muscular scars distinct ; anterior oval, posterior 

 nearly circular. L. 0*5. B. 0-6. 



Var. rosea. Shell rather more oval and glossy, with a 

 purplish streak on either side of the beak in each valve, and 

 the rays on the larger valve of a more vivid hue. C. rosea. 

 Brown, 111. Conch, p. 105, pi. xlii. f . 6 ; F. & H. i. p. 185, 

 pi. ix. f. 13, 14. 



Habitat : Gregarious in sand^ mud, and gravel on 

 every part of our coasts. I once found live specimens 

 burrowing in the sand at Oxwich Bay, Glamorganshire, 

 on the recess of an unusually high spring tide ; and it 

 occurs as deep as 72 f. in Shetland. It usually frequents 

 the laminarian zone. The variety is equally diffused in 

 the British seas, and ranges fi'om Norway to the Medi- 

 terranean ; Weinkauff has taken it at Algiers in brackish, 

 water. C. gibba is not uncommon in post-pliocene and 

 pliocene deposits, e. g. at Belfast (Grainger) ; raised 

 beach at Moel Tryfaen (Darbishire) ; Scotch and Irish 

 glacial beds (Smith) ; Norwich Crag at Bramerton 

 (Woodward) ; Red and Coralline Crag (Wood) ; " gla- 

 cial '^ formation near Christiania (Sars) ; Nice (Risso) ; 

 Belgian tertiaries (Nyst) ; Sicily (Philippi) ; and T no- 

 ticed it in M. Mace^s collection of upper miocene fossils 

 from Antibes. In a recent state it is universally distri- 

 buted throughout the North Atlantic, Irom the Loffoden 



D 5 



