抄録
1. A quantitative survey of the aquatic insects in seven tributaries of the upper region of the Chikuma River has been undertaken at 22 stations by members of the research group of Chikuma from March 1957 to January 1958. 2. The number of species collected from these stations was 53,among which 16 were Trichoptera, 12 were Ephemera, 6 were Diptera and the rest belonged to Coleoptera and Neuroptera. 3. The dominant species in the upper region of the river were found to be Ephemera, but in the lower region Trichoptera species were abundant. When the type of river becomes "Bb" the nymph of Potamonthus kamonis took the
