抄録
The small freshwater shell known to be the ice age relic species, Pisidium nipponense Kuroda, distributes in Yamagata, Niigata and Nagano Prefecture in our country.
In this paper the writer has attempted to investigate the diatom t h anatocoenoses in the interior body and the digestive organ of the shell, which was collected from the small pond of Sphagnum-bog at Mt. Ogenashi located in the south-western part of Niigata Prefecture.
As a result of analysis on some diatom valves of the small tyipe, Eunotia pec t inalis var. minor, Pinnularia braunii, P. interrupta, P. subcapitata and Neidium alpinum, were detected together with Protozoa, Euglena sp., Acella sp., Paramecium sp., and Trichocera sp. of Trichocercidae.
