The forming season of annual rings, i. e. translucent and opaque zones, in the otoliths of marine teleosts Argyrosomus, Lateolabrax and Mylio caught in the Inland Sea of Seto and Pseudosciaena caught in the East China Sea, have been made clear as follows:
(1) The translucent zones in the otolith of these fishes are formed generally from summer to autumn, and the opaque ones from winter to spring of the next year.
(2) Accordingly, calcium carbonate is deposited abundantly on the surface of otolith during summer-autumn, while it is scantily deposited during winter-spring.
(3) The translusent and opaque zones in the otolith of Argyrosomus, Lateolabrax and Mylio can be used for the estimation of age. But the zones of Pseudosciaena must be used carefully for this purpose.
(4) The status of the formation of the annual rings i~ different between Pseudosciaena in the East China Sea and the others in the Inland Sea of Seto.