The Sasagami hills located to the east of the Niigata plain are one of the most suitable area for the study of the Shibata-Koide tectonic line (Yamashita, 1970). The movement of this tectonic line since Miocene is closely related to the tectonic development of the Niigata Cenozoic sedimentary basin. In addition in this area, it was said that the Pleistocene strata correlative to the "Yashiroda Formation", which gives rise to some problems in relation to the standard stratigraphy of Niigata prefecture, are widely distributed. In this paper, the present writer intends to describe the detailed stratigraphy of the Miocene to the Pleistocene strata especially of the "Yashiroda Formation", and to restore the movement of the Shibata-Koide tectonic line. Results of the research are summarized as follows: 1. On the east side of the Shibata-Koide tectonic line, the Miocene series are divided into the Arakawa Formation and the Yamanokami Formation, which unconformably overlies the granitic basement of the Gozu mountains. 2. On the west side of the tectonic line, the continuous deposits from the Miocene to the Pleistocene are distributed on the Sasagami hills. They are classified into the Sakanaiwa, the Haguro, the Dainich, the Sasagami Formations, the Zingamine conglomerate member and terrace deposits. 3. Based on the lithologic facies and the fossils yielded, the Sasagami Formation can be correlated to the Uonuma Group and not to the "Yashiroda Formation". 4. Well developed terraces on the west and the south of the Sasagami hills are divided into the following three groups from their relative height: T1 group (20〜30m in relative height), T2 group (1〜15m) and T3 group (0〜2m). 5. The Shibata-Koide tectonic line in this area may be represented by a step-fault system with westerly throwndown sense. The total throw is estimated more than 4000 m. 6. The notable appearance of the Shibata-Koide tectonic line might be in the late Miocne to the Pliocene, and the particular topography in the Gozu-Sasagami area would be formed since the middle Pleistocene.

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高知県横倉山東部山麓の2地点から,下部石炭紀上部ビゼー世を示すサンゴ化石を多数発見した.本論文において,上記産地の地質を報告し,あわせて同産の新属新種と考えられる四射サンゴ1種を記載する.本地域の下部石炭系を「文徳層(新称)」と命名する.文徳層は,粘板岩を主とし基性凝灰岩を爽在する厚さ200mほどの地層で,下部白亜系中の断層帯にそって幅せまく分布している。全体として,蛇紋岩中の捕獲岩状の産状を呈し,断層帯中には,下部石炭系以外に,岩相上シルル-デボン系と考えられる地層や,同じく上部ペルム系と思われる地層をともなっている.サンゴ化石は,上記基性凝灰岩中の石灰岩レンズ,および蛇紋岩中の捕獲岩として産する石灰岩プロックより産する.Aulostrotion yokokuraense(新属新種)は,Lithostrotion科に含まれるcerioid型の群体サンゴで,aulos様の軸構造をもつことを特微とする.この構造は,正規のaulosが,主セプタが軸部で湾曲し相互に連結することによって形成されるのと異なり,ドーム状に盛り上った床板によって形成されるのを特微とする.このような特微的なaulos様の構造を,新たにPseudoaulosと名づける.

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Recently new materials of Stegodon orientalis OWEN were discovered from Murakashi Quarry, Kuzuu-machi, Aso district, Tochigi Prefecture. Those materials consist of fossil bones and molars obtained from the fissure-filling deposits, and are considered to belong to one young individual. The molars are composed of ₂DP, DP₄, M₁. The measurements of those molars indicate that, for example in the case of M₁, there are some characteristics of narrow crown breadth, high lamellar frequency and thin enamel. It is remarkable that these characteristics are common to other two specimens from Kuzuu area which were formerly described by TOKUNAGA and TAKAI (1938) and SHIKAMA (1949). Nevertheless, in comparison with other specimens of Japan and China, there seems to be some differences with each other in some degrees. It may suggest that the differences are due to geographical or chronological variation. According to the analysis of pumice grains included in the yielded sediments, the horizon of the present materials is correlative with the Lower Kuzuu formation and is contemporaneous with the Tama Loam stage of the Middle Pleistocene.

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