68 



12. 

 Radula. Favan.t.AS.LS. 



T. with a convex, fub-orbicular, white fhell; befet 

 with numerous fine fliarp-edged flrias concentrically : ex- 

 tremely rough to the touch like a rafp : umbo central, 

 fmall ; apex turned to one fide, very little projefted . 

 umbonal region much depreffed, and marked with an 

 oblong cordiform cavity ; a flexure, at the pofterior end, 

 running from behind the umbo to the front angle, not 

 quite parallel with the cartilage flope : hinge with two 

 fmall teeth in each valve fl;anding a little oblique, no la- 

 teral ones, Infide white, not glofly ; a border round the 

 margin more perfeftly white than the reft : cicatrix nar- 

 row, running downward, nearly parallel with the margin. 



This fpecies has much the habit of x\\^ projicua, but is 

 eafily diftinguifhed from it externally by the beak being 

 Jefs produced, by the cordiform depreftion ; by the flex- 

 ure at the pofterior end, and by the fuperior convexity 

 and want of the longitudinal flricc. Internally by not 

 having any lateral teeth or groove: in the fliape and fitu- 

 ation of the tongue or cicatrix ; and in being invariably 

 white. 



With thefe flrong and eflential charafteriflic diflinftions, 

 it is hardly poffible to conceive thefe two fliells can have 

 been confounded, and yet it is fomewhat extraordinary, 

 that a fliell fo abundant as this is on fome of our coafts, 

 fhould have remained fo long unnoticed by thofe who 

 have written profefledly on the fubjeft ; for we cannot 



affix 



