62 



white, gloffed with a pearly hue, as viewed in fome par- 

 ticular lights ; umbo placed nearly central, very fmall, 

 pointed, and turned a little to one fide: the anterior fide 

 flopes very confiderably to an obtufe point ; the oppofite end 

 is much larger and perfeftly rounded. Infide finooth, 

 glofiy- white, with ufually more ox^, lefs tinge of yellow 

 towards the beak ; hinge furniflied with three teeth in 

 one valve, one of which is lateral, not very remote ; in 

 the other valve only two fmall central teeth. 



The remarkable charafter of this fliell is, that the valve 

 pofTefled of three teeth, or (as Doftor Pulteney ex- 

 prefTesit) the left valve, is finely, regularly, and elegantly 

 ftriated in a diagonal direftion; but not very confpicu- 

 ous without the afiifl;ance of a lens ; the other valve is 

 quite plain, except the ufual concentric wrinkles, which 

 are faint; this valve turns a little inwards, at the point of 

 the produced end, to correfpond with the other which 

 reflefts at that part. It is fubjetl to fome variety, with 

 refpeft to the diagonal flri?e peculiar to the finifl;ral 

 valve; in fome thefe run all over, except down the car- 

 tilage flope ; in others only half way from the finaller 

 end, the larger end being only marked with concentric 

 wrinkles. 



This fpecies might readily be confounded with the T. 

 tenuis, but is broader in proportion to its length, and 

 more produced and pointed at the fmaller end : it is in- 

 deed more like the T. Ixta in fliape, but greatly inferior 



in fize. 



We 



