MODIOLA. CONCHIFERA. 85 



dermis green ; hinge with two teeth in one valve, and one in the 

 other. 2 inches long. Inhabits Indian seas. Chem. viii. pi. 83, 

 fig. 745. 



M. edulis, Lin. Shell oblong, convex, smooth, flattish on the pos- 

 terior, and somewhat angulated and keeled on the anterior side ; 

 beak terminal and pointed ; colour blackish-blue, radiated, and 

 covered with a brown epidermis. 2 inches long. Inhabits coasts 

 of Europe. B Penn. Brit. Zool. 



This species is extremely common on the coasts of Britain, and is used as food. 

 It is, however, not always safe ; for mussels from particular places, or at particular 

 seasons, have been found deleterious. Small pearls called seed-pearls are frequent- 

 ly found in the inside. The M. incurvatus and pellucidus appear to be only varieties 

 of this species. 



Gen. 29- MODIOLA, Lam. Mytilus, Lin. 

 Shell subtransverse, equivalve, regular, with the posterior side 

 very short ; beaks almost lateral ; hinge without teeth, late- 

 ral and linear ; ligament almost interior, in a marginal fur- 

 row ; muscular impression sublateral, elongated. 



M. vulgaris, Flem. (M. modiolus, Lin.) Shell oblong, gibbous, 

 smooth, the posterior side obliquely dilated above the hinge ; apex 

 rounded. 4 or 5 inches long. Inhabits European seas. B. 

 Browns Illust. pi. 29, fig. 1, 2, 3, 4. 



The shell of this species is the largest of the genus, being sometimes found six 

 inches long. It is covered with a purplish black epidermis. Young shells are yel- 

 lowish or chestnut, with brown rays, and have the epidermis hairy towards the 

 margin. In this last state it is the M. barbata. 



M. sulcata, Lam. Shell oblong, tumid and angular beneath, with 

 longitudinal divaricated striae j margin of the ligament crenated ; 

 colour bluish-white ; epidermis yellow. 1 J inch long. Inhabits 

 Indian seas. Chem. viii. pi. 85, fig, 760. 



M. securis, Lam. Shell oblong, incurved, acutely carinated below ; 

 epidermis blackish ; inside violet. If inch long. Inhabits coasts 

 of New Holland. Lam. vi. 1, 113. 



M. discrepans, Lam. Shell dark blue, transversely ovate, compres- 

 sed, with the two sides longitudinally ribbed, and plain in the 



middle. 1 to ! inch long. Inhabits British seas. B Brown's 



Illust. pi. 29, fig. 8. 



M. discors, Lam. Shell transversely suboval, very convex, semi- 

 transparent, with the two sides longitudinally ribbed, and plain 

 in the middle ; colour pale greenish or reddish- white, with a glos- 

 sy olive epidermis. ^ inch long. Inhabits coasts of Northern 

 seas. B Browns Illust. pi. 29, fig. 10. 



M. lithophaga, Lam. Shell elongated, cylindrical, straight, tumid 

 below ; extremities obtuse, with minute longitudinal decussated 

 striae ; epidermis chestnut or greenish ; inside bluish- white. 1 

 inch long. Inhabits Indian, European, and American seas.- 

 D'Argenv. pi. 26, fig. K. 



Fossil species of this genus are found in Britain in the oolite, carboniferous lime- 

 stone, lias, green-sand, and London clay. Flem. Brit. An. 413. 



