104 



the preceding genus. Shell with one lengthened, sub- 

 lateral, club-shaped muscular impression : hinge lateral, 

 and most generally indented. Lamarck mentions, that, 

 towards the end of autumn, small crabs (Pinnotheres) 

 seek shelter from danger within these shells, without 

 injuring or molesting the animal. v 



Shells longitudinally grooved. 



Mytilus Magellanicus 



Mytilus exustus 



erosus 



bilocularis 



crenatus 



ovalis 



decussatus 



ustulatus 



hirsutus 



Domingensis 



Mytilus 



Senegalensis. 



Shells without longitudinal grooves. 



Mytilus elongatus 



Mytilus afer 



latus 



achatinus 



zonarius 



ungutfiis 



canalis 



planulatus 



ungulatus 



borealis 



■ . violaceus 



angustanus 



opalus 



corneus 



smaragdinus 



Galloprovincialis 



perna 



edulis 



