70 CONCUYUA—ni i HYRA. 23. 



pro magnifudine crassa et valida est. Ex altera parte ah 

 nmbone ad reclam lineam procedit, ex alierd rolundior est, 

 qud sold notd almnde 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. 



siibfnincata. Mactra testd ovato-trigoud intt'quilaterali transversim striatd, 

 umbonibus tumidis recti's. 

 Shell oval-triangular inequilateral striate transversely, with the 



beaks tumid and straight. 

 Mactra subtruncata, Montagu, Test. Brit. p. 93, and Sujipl. 

 p. 34, tab. 27, fig. 1. 

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

 Pennant, iv. p. 194, tab. 5S, fig. 1. 

 Turton, British Fauna, p. 154. 

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

 Dillwyn, 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 trun- 

 cate, 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 



