1954 年 3 巻 4 号 p. 174-179
1. Attempting pollen analysis on the Mogami coal-field and Okitama coal-field of those in Yamagata Prefecture, comparative investigations between strata and distribution of fossil pollen were carried out. 2. In the Mogami coal-field, climatic division and changes of genera between upper formation and lower formation are obvious from the facts of predominance of extinct genera such as Sequoia, Taxodium, Liquidambar, Cunninghamia and others in the stage of the lower coal-bearing fornation and of predominance of temperate genera such as Alnus, Fagus, Quercus, Juglans and others in the stage of the upper coal-bearing formation. 3. Fossil pollen found in the Okitama coal-field is justly the same as those in the Mogami coal-field. Therefore, it may be concluded that the plant geographical distribution in the whole prefecture of Yamagata is quitely the same and a vast flora consisted chiefly of extinct genera such as Sequoia, Taxodium and others have covered there. 4. From the pollen-analytical results, it is deduced that floral genera of lignites of Mogami coal-field and Okitama coal-field are alike each other and are contemporary with those of Pliocene, Tertiary of the Mogami district.