Systematic and ecological studies on mysidacea collected by the bottom-net

A list of the 21 species represented in the collection by the bottom-net is given. Of these, 5 are impossible to be identified with the already known species, especially 2 are reserved as their genera are undecided. It is found that there are 2 races inHolmesiella affinis Ii, the large-sized and the small-sized, as like as the most related species,H. anomala Ortmann. As to a species,Pteromysis amemiyai Ii, the development of the marsupium is discussed on the basis of an adult female collected by the ORI-net. The occurrence of 2 species,Petalophthalmus oculatus Illig andPseudomma calloplura Holt andTattersall, is a new record in the Pacific. For the former species, moreover, an ecological property of the habitat is discussed.