42 



Orbiculata, Shell white, orbicular, dei)refled, and cancellated : the umbo 

 Tab. 29. f. 7. remarkably finall, beneath which is a minute cordiform dc- 

 preflion, Infide white ; margin plain : teeth, two primary 

 approximate, and one remote Handing tranfverfe ; the mar- 

 gin where the lateral tooth is placed projects into an angle. 

 Diameter five eighths of an inch. 



This fiiell has probably been confounded with Vetius ti~ 

 genua, but it differs fomewhat in contour, is not fo flat, more 

 orbicular, and more coarfely decuHated, and the lateral tooth 

 is much more remote than in tigerina. 



Found on the fliore near Dunbar, bv Mr. Laskey. 



DrsEBA, Venus dysera, Gmel. Syst. p. 32G8. Tart. Lin. iv. p. '1\Q. 



Chem. Conch, vi. t. 28. f. 287—2.90. 

 Lister Conch, t. 277 — 278. 



Shell fub-ovate, fub-cordate, with difiant concentric, ele- 

 vated, and reflected ridges ; the interltices coarlcly ftriated 

 in a longitudinal direc^lion : umbo fmall, and much reclined, 

 beneath which is a cordiform depreffion : the colour is white, 

 but on the cartilage flope of one valve are feveral tranfvei-fe 

 rufou.s-brown lines. Infide white : the hinge lurnilhed witli 

 three teeth in each valve, but in that which is defiitute of the 

 markings on the cartilage flope, the outer tooth next to the 

 beak is very minute : the margin is crenulated. Diameter 

 not quite three quarters of an inch. 



Sevcra 



