29 



when fliut, have a large oval gape or opening in front, 

 oppofue the hinge. Infide white: hinge furnidied with 

 a fmall plate, or rudiment of a tooth, projetling inwards. 



There feems to have been various opinions, with re- 

 fpe6l to the clafs in which this fliell fliould be placed. 



Mr. Pennant, who firft gave it to the public, met 

 with it in the Portland Cabinet ; and feemed to be doubt- 

 ful with regard to the genus in which it ought to be 

 placed, by the trivial name of Dubia he affixed to it. 



Da Costa has placed it with his Chama, which con- 

 fifts chiefly of Linncean Myce. Do6lor Pulteney has 

 made it a Pholas ; we prefume under the authority of 

 Do6lor Solander. It does not however appear that 

 there ever were fufficient grounds for placing it in the 

 Pholas senus. Even Dottor Pulteney himfelf remarks, 

 that he has feen feveral of thefe (hells, but had not ^^.en 

 one with the accefTory valves, the effential part of the 

 characler of that trenus. 



O 



Mr. Pennant and Da Costa mention its polTeffing 

 a tooth, or the rudiment of one. This circumftance per- 

 haps has more inclined us to fix it in the Mya genus i 

 others may perhaps hereafter remove it to the Mytilus ; 

 for the fmall elevation of the hinge is fcarccly to be deno- 

 n)inated a tooth. 



In 



