158 ALLAN HANCOCK PACIFIC EXPEDITIONS \0L. 20 



PLATE 2 



Fig. 7. Choromytilus chorus (Molina) 1782. Chile. (Chace collec- 

 tion) Length: 115 mm. 



Fig. &. Choromytilus chorus (Molina) 1782. Chile. (Chace collec- 

 tion) Inside, showing partly separated posterior retractor 

 scars and pittings in the ventral half of the valve. 

 Length: 128 mm. 



Fig. 9. Crenomytilus grayanus (Dunker) 1853. Japan. (San 

 Diego Museum) Length: 111 mm. 



Fig. 10. Crenomytilus c/rayanus (Dunker) 1853. Japan. (San 

 Diego Museum) Enlarged part of ventral margin showing 

 the fine crenulations. 



