The following Japanese species belong to Rissoina (s. l.), viz. Phosinella media, Rissolina costulata, R. plicata, Zebinella striata, Apataxis cerithiformis, Schwartziella otohimeae and Sulcorissoina imbricata, all of which are here examined, and the general shape is allied to that of Rissoacean groups. Their characteristic features are as follows : 1. They have an opercular process (apophysis) at the inner side of the operculum for the attachment of the retractor muscle fibres. This is one of the distinguished points from Atlantorissoina. 2. The penial duct communicates to outside with a narrow slit and is surrounded by a prostate-like tissue. The male genital tract is a narrow linear canal without a prostate gland. 3. The female genital system is quite similar to that of A. chesnelii from the Atlantic Ocean.

View full abstract

In this paper, the basal metabolism of some fresh-water molluscs in Lake Biwa-ko (Corbicula sandai, Unio biwae, Hyriopsis schlegelii, Cristaria plicata and Heterogen longispira) were reported (Tables 1-5). The respiratory value of Hyriopsis schlegelii (shell length 14 cm) is 0.2 calories per day during summer and 0.04 calories per day during winter. In the case of Corbicnla sandai (shell length 3 cm), 0.05 calories per day during summer and 0.01 calory per day during winter. In Heterogen longispira (5.5 cm), 0.07 calories per day during summer and 0.02 calories per day during winter.

View full abstract