Venus (Japanese Journal of Malacology)

Taxonomic Study of Japanese Species of Glossaulax (Gastropoda : Naticidae)

Ryuichi MAJIMA

Article type: Article
1987 Volume 46 Issue 2 Pages 57-74
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_57

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This study deals taxonomically with Japanese fossil and modern species of Glossaulax. The following species are recognized in Japan : Glossaulax didyma (Roding), G. bicolor (Philippi), G. hyugensis (Shuto), G. hagenoshitensis (Shuto), G. nodai Majima, G. reiniana (Dunker) and G. vesicalis (Philippi).

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A New Alycaeid Subspecies, Chamalycaeus (Sigmacharax) itonis nakashimai from Tottori-ken, Japan

Hiroshi MINATO

Article type: Article
1987 Volume 46 Issue 2 Pages 75-78
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_75

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Two New Species of the Genus Mesophaedusa (Pulmonata : Clausiliidae) from Shikoku, Japan

Hiroshi MINATO, Akira TADA

Article type: Article
1987 Volume 46 Issue 2 Pages 79-85
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_79

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Systematic Position of Four Buccinid Species Collected from off Tajima in the Japan Sea

Osamu MASUDA, Tadashige HABE

Article type: Article
1987 Volume 46 Issue 2 Pages 86-90
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_86

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The systematic positions of four buccinid species collected from off Tajima in the Japan Sea are corrected by the radular feature as follows : Buccinum acutispiratum Dall to Reticubuccinum acutispiratum (Dall) ; Volutopsius hirasei Pilsbry to Habevolutopsius hirasei (Pilsbry) ; Volutopsius middendorffi emphaticus Dall to Lussivolutopsius emphaticus (Dall) ; Volutopsius furukawai Oyama to Lussivolutopsius furukawai (Oyama).

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Identity of Euprymna berryi Sasaki, 1929 (Cephalopoda : Sepiolidae)

Takashi OKUTANI, Eiichi HORITA

Article type: Article
1987 Volume 46 Issue 2 Pages 91-107
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_91

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As the results of critical observations on fashion of arm sucker enlargement, morphology of tentacular suckers and bodily and spermatophoric proportions, it was concluded that the genus Euprymna in the Japanese waters contains two sympatric species, E. morsei (Verrill, 1888) and E. berryi Sasaki, 1929.

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Histochemical and Ultrastructural Studies on the Amatorial Organ of Hemiplecta distincta (Pfeiffer) : (Pulmonata : Ariophantidae)

Somsak PANHA

Article type: Article
1987 Volume 46 Issue 2 Pages 108-115
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_108

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Histochemical and ultrastructural studies were carried out on the amatorial organ of sexually-matured snails, Hemiplecta distincta (Pfeiffer), to observe the morphology and determine the nature of secretion. The amatorial organ is situated in a right anterior position near the genital opening. The organ consists of circular and longitudinal muscles, granule secreting cells (M1) which secrete neutral-mucopolysaccharides, mucocytes (M2) which secrete acid-mucopolysacharides and lumen cells (LC) which produce zymogenic granules. The ultrastructure of granule secreting cells is discussed. The cells are identified by their superficial location and by the character of their dense mucous granules. Cytoplasm have a large quantity of rough endoplasmic reticulum, Golgi bodies and free ribosomes.

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On the Density Effect in Populations of the Mussel, Mytilus galloprovincialis

Akimichi HOSOMI

Article type: Article
1987 Volume 46 Issue 2 Pages 116-126
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_116

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In natural populations of the mussel, Mytilus galloprovincialis, the higher the population density is, the lighter the average weight of individuals is. That is, the population density and the average weight of individuals are inversely proportional. In addition, the population density is directly proportional to the biomass. Therefore, individuals are small and their growth is delayed where the biomass is high in the populations. When samples are compared between surface and bottom layers, the average size of individuals in the surface layers are significantly larger than that in the bottom layers. This seems due to the difference in growth rate between the two layers. In places where population density is high, the number of dead individuals is large. Dead mussels are almost all small in size. Where the population has a high density and large standing crop, the growth is retarded and thinning out occurs, and consequently the biomass is reduced. Where the density is low and the standing crop is small, the growth of the population continues as a kind of self-regulation within mussel populations.

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Sagamilepeta, a New Genus for "Lepeta" sagamiensis Kuroda & Habe 1971 (Gastropoda : Lepetidae)

Takashi OKUTANI

Article type: Article
1987 Volume 46 Issue 2 Pages 127-130
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_127

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 46 Issue 2 Pages 131-
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_131_1

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[title in Japanese]

[in Japanese]

Article type: Article
1987 Volume 46 Issue 2 Pages 131-132
Published: July 15, 1987
Released on J-STAGE: January 31, 2018

DOIhttps://doi.org/10.18941/venusjjm.46.2_131_2

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