136 SPECIFIC 



Specimen deep violet, beaks white ; somewhat 

 triangular. 



Inhabits most seas, at the bottom of which it is 

 found adhering by the byssus in large clusters. It 

 is generally known as the common muscle. 



PLATE XI. 



Fig. 1 . Pinna pectmata . 



Shell transversely striate, wrinkled towards the 

 base. 



Gualt. Test. Tab. 79. A. 



Specimen horn-colour with darker clouds ; about 

 10 obsolete ribs converging to the smaller end; 

 triangular; hyaline; brittle. A smooth variety. 



Inhabits India and Europe. 



PLATE Xn. 



Fig. 1. Argonauta Argo. 

 Shell having the keel slightly toothed on both 

 sides. 



Lister Conch. Tab. 254, 255. 



