魚沼層群より産出した2種のカニ化石
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概要
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Two species of fossil crabs, Macrophthalmus (Mareotis) sp. and Charybdis sp., were found from the Plio-Pleistocene Uonuma Group, Niigata Prefecture, Central Japan. Macrophthalmus (Mareotis) sp. was collected from the Lower Formation of the Uonuma Group. The carapace of the species has many granules on the outer surface and narrow flontal portion. There are two longitudinal granular rows on the branchial region. The species having these characteristics is similar to Recent Macrophthalmus (Mareotis) Japonicus (de HAAN), but differs in its small breath of carapace. Macrophthalmus (Mareotis) was found with molluscan and foraminiferan fossils living in the inner bay. Charybdis sp. was collected from the lower part of the Middle Formation of the Uonuma Group. The species has twin ridges observable in the intestinal region. Moreover, there are ridges and granues one behind another in both branchial regions. These characteristics are very similar to those of Charybdis variegata (FABRICIUS). The species was found with molluscan fossils living in fine-sandy bottom under the shore water.
- 地学団体研究会の論文
- 1986-07-25