402 



THE MUSSEL 



CHAP. 



outer and inner gill-lamina (Fig. 103). Seen from the 

 surface (Fig. 101), each lamina presents a delicate double 

 striation, being marked by faint lines running parallel 





with, and by more pronounced lines running at right 

 angles to, the long axis of the organ. Moreover, each 

 lamina is double, being formed of two similar plates, the 

 inner and outer lamdlce, united with one another along 



