Three problems on the early Pleistocene molluscan fauna are discussed in this paper.
1. Fresh water molluscan fauna in Paleolake Biwa and its environs
The fresh water molluscan fauna in Lake Biwa consists of 43 species and bears 19 endemic species. A part of the fauna occurs in lacustrine sediments of the Paleo-Biwa, Osaka and Tokai groups. It seems that the speciation and changes in distribution correspond to the geologic development of the lakes.
2. Continental coastal mollusks
Continental coastal mollusks are now living in inner bay in Japan. They are on the decline in number and distribution. Some of the elements of the continental coastal fauna are found in early Pleistocene formations. Considering the vertical and geographical distribution of the fauna in age from early Pleistocene to Recent, same problems as the fresh water molluscan fauna occur in this case.
3. “Omma-Manganzi” fauna
There is a problem on the cold sea water type “Omma-Manganzi” fauna in the Pliocene Wakimoto stage. In comparison with the Pliocene faunas and floras in Kamchatka and Alaska which indicate environment warmer than now, it needs to check the age and the features of the “Omma-Manganzi” fauna. Conclusion on this problem is postponed because of the synthesis of various data makes possible to solve the problem.
