70 CONCHYLIA— i)/r/fyi?^. 23. 



pro magnitudine crassa et valida est. Ex altera parte ab umbone ad 

 rectam lineam procedit, ex altera rotundior est, qua sold notd abunde 

 distinguitur ab aliis" This shell for its size is thick and strong. 

 On one side it runs in a straight line from the beak ; on the other it 

 is rounded, by which mark alone it may be sufficiently distinguished 

 from all others. 



subtruncata. Mactra testd ovato-trigond incequilaterali transversim striata, umboni- 

 bus tumidis rectis. 

 Shell oval-triangular inequilateral striate transversely, with the 



beaks tumid and straight. 

 Mactra subtruncata, Montagu, Test. Brit. p. 93, and Suppl. p. 34, 

 tab. 27, hg. 1. 

 Linn. Trans, viii. p. 71, tab. 1, fig. 11. 

 Pennant, iv. p. 194, tab. 55, fig. 1. 

 Turton, British Fauna, p. 154. 

 Dorset Catal. p. 38, tab, 5, fig. 10. 

 Dilhvyn, Descript. Catal. p. 141. 

 Turton, Conch. Diet. p. 82. 

 Trigonella subtruncata. Da Costa, Br. Conch, p. 198, 

 Mus. nost. Western coasts, and Ireland. 



Shell three quarters of an inch long and more than an inch broad 

 thin and convex, of a yellowish horn-color, rough and brown at the 

 produced end, regularly striate transversely : one side truncate, the 

 other produced in a straight line to a rather acute point; beaks not 

 central, tumid and prominent, without curvature. 



A variety is found, especially in Ireland, much stronger, more 

 convex and opake, of a more regularly triangular shape, not 



