38 CONC HYLI A— Z>/r£ryi2^. 11. 



Named from Mr. Swainson, of Elm Grove, near Liverpool, 

 long- known in the annals of British Conchology. 



decussata. gpHENiA testd ovutd decussatifii striata, margine undato. 

 Shell oval, with decussate striae, and the margin uudate. 

 My a decussata. Montagu, Suppl. p. 20, tab, 28, fig. 1. 



Pennant, Brit. Zooi. iv. p. 167. 



Wood, Conch, p. 99. 



Dillwyn, Descript. Calal. p. 46. 



Turton, Conch. Diet. p. 102. 

 Taken in the Firth of Forth, by Capt. Laskey. 



We are unacquainted with this shell, but conclude from Mon- 

 tagu's description, that it falls into this genus. It is said to be 

 half an inch long, and rather more in breadth, oval, white, 

 undulate at the margin, with irregular transverse ridges which are 

 crossed by regular longitudinal striae, forming tubercles at the 

 anterior end. In the hinge a broad erect tooth in one valve, 

 and a projecting plate with a small indentation in the other. 



11. COUBVLA.—BRUGUIERE. 



Testa suhtrigona, insquivalvis, incequilateralis, chaisa. Cardo 

 valv<s sinistrce dente conico cumjoveoldadjectd, valva dextrce dente 

 cochleariformi cum Joveold; laleralibiis mdlis, Ligamntum 

 internum. 



