Before the outbreak of the war with Japan the author had the intention to publish an extensive account on the occurrence of an aestuarine fishfauna in and in front of the large aestuarines and river-mouths so often found in India, Burma, Malaya, Thailand and Indo China and in the Greater Sunda Islands, Sumatra and Borneo, the rivers of the latter two islands being the special field of investigation. However as a consequence of the war all, thus far, unpublished notes and the greater part of the collections were lost as is the case with a most interesting sample of an aestuarine fishfauna from South New Guinea, where biologically the same conditions exist as in Sumatran and Bornean rivermouths. This last collection remained partly unpacked when war broke out and its still unassorted part disappeared. Only about 20 % of the total was found back in a more or less good condition.