103 



Modiola vagina 



Modiola discrepans 



picta 





discors 



sulcata 





trapezina 



plicatula 





cinnamomea 



semifusca 





silicula 



securis 





plicafa 



purpurata 





semen 



barbata 





lithophaga 



Modiola caudigera. 







MYTILUS. 



mytilus exustus. — Linn. 



Mawes Linnctus, plate 16, Jig. 2. 



The genus Mytilus now consists of such examples of 

 the Liunsean Mytili, as are regular, equivalve, and lon- 

 gitudinal shells; of a solid and not lamellar substance, 

 (as in the Oyster); with pointed apices at the inferior 

 end, nearly straight or slightly curved; and attached 

 to other substances by a byssus of a short thick texture ; 

 the cardinal ligament lateral, and a considerable por- 

 tion of it internal, by which, as well as the different 

 position of the apices, it is easily distinguished from 



