Sixteen new species of the genus Amalda of the Family Olividae are described. They are, A. (Alcospira) fasciata n. sp., A. (Al.) ponderi n. sp., A. (Al.) pullarium n. sp., A. (Al.) coenobium n. sp., A. (Al.) colemani n. sp., A. (Al.) lanceolata n. sp., A. (Al.) rubrofasciata n. sp., A. (Exiquaspira) bulbosa n. sp., A. (E.) festiva n. sp., A. (E.) rottnestensis n. sp., A. (E.) sydneyensis n. sp., A. (Mundaspira) pinguis n. sp., A. (M.) nitidanosum n. sp., A. (M.) tenuis n. sp., A. (Gracilispira) acuta n. sp. and A. (G.) procerum n. sp. all from Australia.

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A new subspecies of Euhadra grata (Gude) is described and named echigoensis. This subspecies is characterized by having sharply angulated periphery of the body whorl and distinctly raised growth riblets as well as short vagina and long stalk of receptacle seminis.

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A valvatid snail found in the Lakes Kizaki and Nakatsuna, Nagano Prefecture, is the closest to Cincinna simusyuensis (Miyadi, 1935), but differs therefrom in having 60-65 ciliated growth lines. Thus, it is here described as a new species Cincinna kizakikoensis.

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Phenacovolva (Pellasimnia) mikado n. sp. from off Shikoku, Japan, is the largest among the subgenus. This is pure white with elongated rostra. The posterior rostrum is characterized by its parallel-sided duck-bill shape.

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Cyclostremiscus chamizal, n. sp., and Solariorbis cortezi, n. sp., are described from the northern Gulf of California, Mexico, and compared with their closest congeners.

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Among the benthos materials collected by the Icebreaker Shirase from Breid Bay, Antarctica, a new species of the genus Brookula, B. (s.s.) sinusbreidensis was found. The description is given.

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The orange species of Rostanga, previously known as R. muscula : Baba, 1935, or R. arbutus : Baba, 1937, is reidentified as R. orientalis Rudman & Avern, 1989. The black (purplish black) species of Rostanga, R. arbutus : Baba, 1937 (in part), is reidentified as R. risbeci Baba, n. sp.

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Hemocytes of Heminerita japonica were found to be amoebocytes. The hemocytes migrated chemotactically to H. japonica serum in low level. Chemokinesis of the hemocytes was also observed in 20% serum. The hemocytes migrated to a suspension of Vibrio parahaemolyticus strain D-3. The migration to the bacterium was not stimulated in the molluscan serum. From these evidences, the hemocytes are suspected to participate in the clearance of the bacterium from H. japonica.

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Clithon retropictus ranged in the highest density at Hashizu estuary where salinity of water fluctuated between 5 and 26‰, while Nerita albicilla and Heminerita japonica ranged at the coasts along Cape Muroto with salinity levels of 30-38 and 10-42‰ respectively. When they were maintained in water with different salinity levels, C. retropictus survived at a wide salinity range while N. albicilla and H. japonica died in low salinity levels.

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Chromosomes of 11 species in the Diplommatinidae have been studied. All of these species had the chromosome number 2n=26. Chromosome complements of these species consisted of metacentrics and submetacentrics. Integrated optical density (OPTDI) of the nucleus stained with Feulgen dye has been measured in 15 species of the Diplommatinidae. Larger size species showed higher value in OPTDI. The OPTDI values differed with inter- or intraspecies.

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[in Japanese]

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