114 MYTILID.E. 



scription agrees ad amussim with the common shell which 

 is usually regarded as M . modiolus, the animal of which 

 he says is eaten in Norway. According to Lamarck, his 

 Modiola tulipa inhabits " les mers d'Amerique." Our 

 shell is the Modiola vulgaris of Fleming. The young is 

 the Mytilus curtus of Pennant and the Modiola barbata 

 of Macgillivray. 



3. M. barba'tus *, Linne. 



M. barbatus, Linn. Syst. Nat. p. 1156. Modiola barbata, F. & H. ii. p. 190, 

 pi. xliv. f. 4. 



Body reddish-brown : mantle not folded : gills narrow, 

 coarsely pectinated ; lower pair more than twice the depth of 

 the upper ones. 



Shell irregularly triangular, pointed at the smaller end and 

 expanding obliquely outward to a broad and obtusely rounded 

 edge in front, compressed, but gibbous towards the beaks, solid, 

 somewhat glossy on the upper part, but elsewhere of a dull 

 hue owing to the close investment of the bearded epidermis : 

 sculpture, numerous concentric membranaceous ridges : colour 

 yellowish-red, or scarlet: epidermis thick, yellowish -brown, 

 minutely but deeply striated lengthwise, thickly foliated, and 

 rising on the posterior side and in front into a fringe of thorn- 

 like projections, which are distinctly serrated or barbed on the 

 side facing the ventral portion ; the epidermis is reflected over 

 the front edge and forms a glistening band inside it : margins 

 thick, straight or incurved on the ventral side, angulated 

 behind, and obtusely rounded in front : byssal sinus large and 

 rather long : beaks small, close together, incurved, placed (as 

 in M. edulis) very near the point of the shell: hinge-line 

 straight, occupying about one-half of the dorsal margin : liga- 

 ment narrow, much sunk: hinge-plate thick, deeply grooved 

 for the reception of the ligament : hinge toothless, reflected : 

 inside highly nacreous and iridescent, sometimes beautifully 

 stained with purple on the posterior side and occasionally 

 studded with sessile pearls : muscular scars indistinct : pallial 

 scar well defined. L. 1-8. B. 1. 



Var. oblonga. Shell more elongated and tumid ; ventral 

 * Bearded. 



