PLATE CXXV. 



her on different parts of the sea-coast, and especially on that of 

 Cornwall, as will appear hereafter. A few shells of the species before 

 us were met with by her in the summer of 1801, on Hale sands under 

 Lelant in that county, and it is said by the country people they are 

 at times found on that coaft in some plenty. 



Though hitherto unknown as a British shell, it has been before 

 discovered in the Mediterranean sea ; for there can be no hesitation 

 in admitting it to be the shell figured by Chemnitz, as above quoted. 

 Gmelin refers to the two figures in that Work, No. 232, and 233, 

 for his species glauca ; and the description corresponds in general 

 with them, though not exactly in the colour of the rays.- — Gmelin 

 has another species of Mactra, grandis, which we at first suspected 

 to be the same as our shell. It agrees precisely in the colour of 

 the rays, but from the figure in Chemnitz's work, quoted by Gmelin 

 for that species, these rays, it appears, are far more minute, than in 

 our shell, and are also decussated by others in a concentric direction ; 

 ■*— the outline of the latter is also different,, 



