The author has determined the vanadium and chromium contents of the shallow-water deposits collected from all the sea-coasts of Honshu (Japan) and Korea. In this paper, the analytical results of 81 kinds of deposits from Japanese sea-coasts are described.

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In this paper, the vanadium and chromium contents of 59 kinds of deposits from Japanese and Korean sea-coasts are described. Summarizing these results and those shown in the previous paper, the author has found that the vanadium and chromium contents are in general higher in muds than in sands, and as for the sands, they are higher in the blackish ones which are low in SiO₂ and high in Fe₂O₃, MgO, etc. from Aomori, Iwate, Kanagawa and so on, and are exceedingly lower in brownish or yellowish sands which are high in SiO₂ and low in Fe₂O₃, MgO, etc. from Korea, Hiroshima, Yamaguchi and some other prefectures. The analytical results of the several fractions into which shallow-water deposits were divided by mechanical analysis are also described.

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1. The author made a schematic explanation of increase of diatoms in relation to chlorinity in the productive zone of various communities in Osaka Bay in summer, as the distributions of communities have a close relation to the surface distribution of chlorinity.
2. The schema coincides with the present state in substance, especially in Skeletonema and Nitzschia-Leptocylindrus-Thalassionema communities. However, some consideration on the effect of temperature may be needed for the case of lChaetoceros- and Lauderia-Guinardia-Thalassiosira communities.
3. External factors by which these schematic distributions are destroyed are thought to be as follows:
(i) Circular current : In the case of decaying communities, the productive zone tends to move more eastward from its optimum region than in the case of normal community.
(ii) Difference of the speed between the decrease of chlorinity and the increase of diatoms : In the case when chlorinity decreases rapidly and excessively, diatoms do not increases correspondingly, and the increase is late behind the decrease of chlorinity.
4. It is concluded that the quantity of diatoms may be expressed as a function of temperature and chlorinity in Osaka Bay.

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