An undescribed goby, Rhinogobius sp. BI (Bonin island type) sensu Suzuki (1992), is now endangered, however, there is little information about their micro-distribution and the habitats which are necessary for their conservation. Field research on Chichi-jima and Haha-jima islands in the Northwestern Pacific was done twice to clarify the present status of the goby populations. The presence of the goby was confirmed at all the stations in the south area of Chichi-jima Island and at four stations of Haha-jima Island. The goby inhabited deep water in streams with sand and gravel, and the population density was assessed to be comparatively high at Tokoyono-taki and Shigure-dam. The specimens collected from Haha-jima Island well matched R. sp. BI from Chichi-jima Island. But, the variation about the numbers of pectoral fin rays and predorsal scales, is low in the specimens from Haha-jima Island. The population of Haha-jima island seems to have low genetic diversity as compared with that of Chihi-jima island. Present study suggests that each population composes an independent local population.

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A single specimen of the muraenid moray eel, Gymnothorax elegans Bliss, 1883 (HUMZ 178664; 591 mm TL) was collected using the bottom longline off Ishigaki Island (60-70 m deep; 24°15'N, 124°10'E), the Yaeyama Islands, Okinawa Prefecture, Japan, in December 2001. It represents the third record of the species from Japan, and the specimen is described.

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In this biogeographical study, we compared 13 rivers in the Chugoku and Shikoku Districts. Cluster analysis revealed that 1) these rivers were divided into 4 groups based on the fish species composition; 2) these groups were corresponded with the geographical location of each river. Such a pattern was clearer in the primary freshwater fishes rather than in the diadromous fishes. We consider that the geological history of the Chugoku and Shikoku Districts can explain such biogeographical pattern.

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On Nov. 5, 2002 more than 200 medusae of Turritopsis nutricula (Hydrozoa, Anthomedusae, Clavidae) were collected in Kagoshima Bay. Most of them were well-grown or possibly mature, and they differ in some respects from conspecific medusae from Kagoshima Bay described by Bigelow (1913) and also from T. nutricula in northern Japan. A description is given based on 10 larger specimens. One medusa could be parasitized by up to 100 or more trematodes. One out of 10 immature medusae with fewer than 30 tentacles degenerated and, following this species' usual course of rejuvenation, formed a hydroid that grew to consist of three zooids at 20°C; a month later this hydroid colony disappeared without releasing medusae. One large individual medusa was cut in half, and one half was further cut into two quarters, but these three pieces did not rejuvenate.

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A living mature female medusa of Melicertum octocostatum (M. Sars) (Leptomedusae, Melicertidae) was collected in the Sea of Japan off the coast of Yamagata Pref., northern Japan in June, 2003. This specimen serves as the basis for the first description of this developmental stage of this species in Japan. The morphology, cnidome on the tentacles and oral lips (atrichous isorhizas and microbasic mastigophores), and egg size (mostly 104 μm in diameter) of this medusa are described, and occurrence records of 23 other medusan specimens of this species from the same area in Yamagata Prefecture are given. In comparison with 7 other described specimens from two localities in northern Japan (Hokkaido and Aomori Pref.), the present specimen is the largest (15.1 mm in both diameter and umbrellar height) and has the most numerous tentacles (at least 80 large tentacles and a nearly equal number of small tentacles). Two individuals of a parasitic trematode were found in the mesogloea of the female medusa.

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This paper concerns a freshwater ostracod, Notodromas monacha, with photographs of its valves and appendages. This species is different in morphology and ecology from other freshwater ostracods. Valves and most of the appendages are characteristic in shape. It usually clings upside down to the under surface of water, and swims slowly there. It sometimes falls, and in the normal posture it rests on the bottom for a long time or swims rapidly for a moment. Then it rises quickly, and hangs again down from the water surface. In Japan it is rare in ponds and paddy fields these days.

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Alpheid shrimps associated with gobiid fishes from the Japanese waters were preliminarily reviewed. Totally 11 species, Alpheus bellulus Miya and Miyake, A. brevicristatus De Haan, A. macellarius Chace, A. randalli Banner and Banner, A. rapacida De Man, A. rapax Fabricius, A. sp. 1, A. sp. 2, A. sp. 3, A. sp. 4, and A. sp. 5, were recognized. Among these, most of the unidentified species are closely related to Alpheus djeddensis Coutière which has taxonomical problem. Therefore, the taxonomic status of these species could not be cleared at present.

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Stirocorsia tosensis (Tosawa et Sugihara) is newly recorded in Kagoshima Prefecture, Kyushu, and S. apicalis Togashi is newly recorded in Gifu Prefecture, Honshu.

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Haltichella nipponensis Habu, 1960, is newly recorded in Ishikawa Prefecture, Honshu.

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Dirhinus secundarius Masi has so far been recorded from Shizuoka Prefecture in Japan and Taiwan. It is newly collected from Ishikawa Prefecture.

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Eleven species of sawflies are recorded from Tsushima, Nagasaki Prefecture, Kyushu, Japan. Out of them, six species are newly recorded from this island.

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As one of the general survey conducted by Union of Taxonomy of Japan, the number of parasitic nematodes from wild and captive avian and mammalian species including man recorded in Japan was presented from an overview of references cited in the publications (mainly the reviews). Hence, 411 species belonging to 37 families were recorded with appendix of all species names and hosts.

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