Bull. U. S. B. F., 1909. 
Plate XIX. 
1 
3 
4 
1. — Interior surface view of the mantle of a male mussel. X 10. 
2. — Interior surface view of the mantle of a female mussel. X 10. 
3. — Lateral view of a mussel with the shell and mantle of one side removed. Slightly enlarged. 
4. — Lateral view of a female mussel with the shell and mantle of one side and the foot, gills, 
and abdomen removed to show the main canals of the genital system. Slightly enlarged. 
Abbreviations: A, abdomen; AAd, anterior adductor muscle; AR, anterior retractor muscle; 
By, byssus; F, follicle containing male genital products; Ft, foot; G, gills; GC, genital 
canals; GP, genital papilla; L, liver or digestive gland; LP, labial palps; M, mantle; Mth, 
mouth; O, ova remaining in the mantle after spawning (4CC); PAd, posterior adductor 
muscle; PM, pallial muscles; PR, posterior retractor muscles; S, shell; U, umbo. 
