On the basis of the collections of the R/V Vityaz in the Banda Sea, Indonesia, a review of the chiton fauna of the genera Belknapchiton and Leptochiton was carried out. Leptochiton commandorensis, until now known only from the northern Pacific near the Commander Islands, is here added to the four known Indonesian deep sea species. This species turned out to be with juveniles in the pallial groove. A scanning electron microscope study of the collected specimens of B. giganteus made a corrected, supplemented description of this rare species possible. The age variability of the valves shape and shell sculpture of the two collected species was studied. Particular attention is paid to the age variability of the number of micraesthetes on the tegmentum grains and the position of the mucro.

Described is a new species of the genus Stenosemus from the Gulf of Alaska. It differs from the other species of this genus from the Northeast Pacific by having longitudinal undulating folds in the pleural areas of the intermediate valves, flattened, smooth dorsal calcareous corpuscules on perinotum and rectangular central teeth of radula.

A new camaenid Aegistohadra baii sp. nov., close to Aegistohadra delavayana but having smaller and more conical shell and anatomically different, was described from Yunnan, southwest China. Helix seraphinica Heude, 1889 was confirmed to be an Aegistohadra species based on structure of genital organs. Cryptozona yunlongensis Chen Y., Chen D. et Zhang, 1997 is transferred to Aegistohadra based on shell and genital characters.

The work is based on a study of long-term collections of molluscs of the family Bithyniidae from the waterbodies of the Tyumen region (Western Siberia), located within the world's largest Ob-Irtysh natural focus of opisthorchiasis. Difficulties with species identifications of bithyniid snails, the first intermediate hosts of Opisthorchis, necessitate the publication of photographic images of Bithyniidae shells and an identification key based on discrete morphological characters. It has been established that 14 species of Bithyniidae belonging to five genera inhabit the Tyumen region, an annotated list of species is given, and a brief zoogeographical description is given. The most abundant species are Digyrcidum starobogatovi and Boreoelona sibirica, whereas Paraelona milachevitchi were found solitary.