In an earlier paper on the phytoplankton organisms of the west coast of India, mention was made of several new taxa (Subrahmanyan, 1958). It is well known that even the finest bolting silk net does not retain all the organisms in the water and quite a lot-the nanoplankton-escape through the meshes. Such organisms amount to as much as 50 per cent of the total quantity of phytoplankters and are of great importance in the economy of the waters (Subrahmanyan and Sarma, 1966). In the present account, four new species belonging to this nanoplankton category are described, three of the genus Haplodinium Klebs emend. Subrahmanyan and one of the genus Mesoporos Lillick; so far, only one species of the former is known from Java; of the latter, only five species, all from Europe (Schiller, 1933-38 and others under references).
