thin, transparent, glossy, brilliant white, reflecting me- 

 tallic colours, anteriorly tapering to a point, posteriorly 

 rounded; beaks small, pointing to wards the longer side; 

 inside smooth, glossy, hinge with a plain denticle and 

 lateral teeth. W. Coasts, Scotland. $...!. 



A. TENUE. Lam. S.Turt. B.p. 53' P.p. 433. 

 MACTRA T. Mont. p. 572. t 11. f. 7. Pen. 4. p. 194. 

 Lin. T. S.p.72. Dor. Cat. p. 33. D. p. 142. 



Turt. C. D. p. 84. Sub-triangular, equilateral, com- 

 pressed, thin, glossy white, pellucid, ventral edge 

 rounded ; hinge with a cloven and a remote lateral 

 tooth in one valve, a single plain tooth in the other. 

 i...0,40. S. Coast. 



A. BOYSII. Lam. 7. Turt. B.p. 53. t. 5,/. 4 5. 

 LIGULA B. Mont. p. 98. t. 3./. 7. MACTRA B. 

 Pen. 4. p. \96.-Lin. T. 8. p. 72. t. 1. /. 12. Dor. 

 Cat.p.93. t.\2.f. 7.D.p. U3.Turt. C. D. p. 

 84. M. ALBA. Wood, Lin. T. 6.p. 174. t. 16. /. 9. 

 to 12. AMP. A. F. p. 433. Ovate, subtriangular, 

 rounded at both ends, anteriorly shorter, thin, com- 

 pressed, glossy white, sloping from the beak at both 

 ends, ventral edge rather suddenly rounded : a single 

 umbonal denticle in each valve and a large lateral tooth 

 on each side in one valve, i f . Common on Sandy 

 Coasts. 



