ijl Mr. William Wood's OlfirviUhns on the 



Tab. XVIIL Fig. 13, 14. 



I believe it has not hitherto been publicly noticed, 



that the common mufcle pofTeilcs teeth ; fuch,, 



* however, is the cafe, and their fituation, clofe to the 



beak of the fliell, was firll: pointed out to me by 



Mr. Boys. 



Thefe teeth are by no means regular, either in their 

 arrangement or fhape; nor is every (hell provided 

 ' with them. The fpccimens in which I have found 



them are of a much larger fize than the common, 

 and generally make their appearance in the Lon- 

 don markets in the depth of winter; but I am told 

 they are not fo much eftcemed as the fmaller 

 ^ ones. 



The teeth are from three to feven in number, and, 

 when examined collectively, refemble in figure 

 and irregularity the knobs of a lobfter's claw. 



PINNA. 



muricata, Linn, SyJl,NaU ed, Gmei. \,p, 3364. 



The two valves of the Pinna are merely united by a 

 thin membrane, which forms a hinge of the moft 

 fimple conflru£tion, without even the veftige of a 

 tooth. 



EXPLANATION OF THE PLATES. 



Tab. XIV. 



Fig. I, 2. The hinge of the My a truncata. (a) The great tooth. 



(b)The 



