69 



We have before remarked the great fimilarity in feveral 

 of the fpecies of this genus, deftitute of fixed difllnguifliing 

 chara6lers, and of courfe individual opinion will be foiuided 

 on the fpecimens confulted. By this rule we cannot at pre- 

 fent be convinced that tlie M. Avo?ieiifis is the fame as M. 

 anatinus, notwithftanding the high confideration we enter- 

 tain for a recent opinion to that effect given in Vol. viii of the 

 Linnean Tranfadlions. 



Mytilus faba, Gmel St/sf. p. 3C59: DecussaTUS. 



Chem. Conch, viii. t. 85. f. 761 ? 



Shell longitudinally ovate, with the umbo at the fmaller end : 

 fides equal. It is very thin, pellucid, of a pearly white when 

 divefted of the epidermis, (which is of a pale olive-brown); 

 and is finely firiatcd longitudinally, crofTed by more minute 

 /Iria in a tranfverfe direction, that gives it a decufiated ap- 

 appearance when examined under a microfcope. The 

 infide is fmooth with a nacred glofs ; at the hinge is a flight 

 indenture, and the margin contiguous (lightly denticulated; 

 and near the front margin is a fingular reflected tranfverfe 

 ridge, but whether this is a conftant charadler, or accidental, 

 cannot be determined : indeed only one valve of this curious 

 little Ihell has come under examination, and that through 

 the favour of Mr. Laskey, who found it in fand on the 

 Scotijlj coafl:. 



It is about one eighth of an inch in length, and not quite 

 fo broad. The convexity of the valve gives it the appear- 

 ance 



