PLATE CLI1. 



PINNA LMVIS. 



SMOOTH PINNA, OR HAM SHELL. 

 GENERIC CHARACTER. 



Animal Limax. Shell sub-bivalve, fragile, erect, gaping at one 

 end, and furnished with a byssus or beard : hinge toothless, and 

 uniting the valves into one. 



SPECIFIC CHARACTER. 



Shell nearly triangular, horn-colour, smooth : valves rugose on the 



posterior part. 



Pinna ljsivis : testa sub-triangulari cornea laevi : valvis posterius 

 rugosis. 



This species of Pinna which differs from any that has been before 

 described as a British shell ; and if we are not mistaken, from either 

 of the Linnaean or Gmelinian species of the genus also ; was received 

 by A. M'Leay, Esq. among other curious shells that were dredged 

 up on the coast of Shetland. 



The difference between this and the other analogous kinds, seems 

 to consist in its being of a more triangular form, and in not having 

 .vol. v: c 



