172 Mr. William Wood's Ohfervations on the 



Tab. XVIII. Fig. 13, 14. 



I believe it has not hitherto been publicly noticed, 

 that the common mufcle pofTefics teeth ; fuch, 

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

 beak of the (hell, was firft pointed out to me by 

 Mr. Boys. 



Thefe teeth are by no means regular, either in their 

 arrangement or fliape; nor is every fhell provided 

 with them. The fpecimens 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 efteemed as the fmaller 

 ones. 



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

 when examined colleftively, refemble in figure 

 and irregularity the knobs of a lobfler's claw. 



PINNA. 



murkata. Linn. SyJl.Nat. ed. Gmel. \.p. 3364. 



The two valves of the Pinna are merely united by a 

 thin membrane, which forms a hinge of the moft 

 fimple conftru6tion, 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 tooths 



Cb)The 



