During recent dives by the crewed submersible Shinkai 6500 in abyssal depths on the landward slope of the Japan Trench (5343-5379 m), five gastropod and four bivalve species were collected from seep environments. The gastropods include a recently described species in the Neomphalidae, two new species in the Provannidae, a single species in the Buccinidae, and a new species in the Cancellariidae. Bivalves are represented by a single species of the Solemyidae, a single species of the Thyasiridae and two species of the Vesicomyidae, the most of which were previously described from greater depths in the same trench.
The vertical distribution of Japeuthria cingulata (Reeve, 1847) was studied on Sakura-jima Island, Japan. Frequency distributions of shell size showed that newly hatched juveniles appeared in April, but their recruitment did not seem to be concentrated in any specific period over a year. In the intertidal area, the vertical distribution range of J. cingulata was larger than that of Cronia margariticola (Broderip, 1833) and Morula musiva (Kiener, 1836). Juvenile J. cingulata occurred in the lower zone, while adults occurred from the lower zone to the middle zone (broadly defined). No seasonal change of distribution in the intertidal area was observed.
The ancient Nakasuji sand dune on Taramajima Island in the Sakishima Archipelago features two layers of intercalated eolian dust paleosol. The eolian dust layers have yielded terrestrial molluscan fossils in large numbers. There are in all 21 species of land mollusc, including six now extinct on the island. The fossils are predominantly minute fossils, but larger specimens are also preserved well without severe damage. This indicates that these assemblages are autochthonous. The species composition of the minute fossils differs from layer to layer. Gastrocopta (Sinalubinula) armigerella and Tornatellides boeningi are dominant in the lower paleosol layer and the underlying sand layer, while Georissa japonica, Carychium cymatoplax, Platyrhaphe hirasei nudus and Aphanoconia yaeyamaensis dominate the upper layer. Judging from the habitats of their Recent counterparts, it is inferred that the fossil assemblages in the lower layers were formed near the coast lines and that those in the upper layer were formed in and around coastal forests. This could be due to a fall in sea level associated with glacial eustasy in the last ice age.