The Akima Formation of the Neogene system mainly consists of pyroclastic rocks and it is divided by lithofacies into seven members. Ten samples from the Akima Formation were analyzed into each assemblage of diatoms. The diatom assemblages are composed of 66 specis and 30 genera. Their names and frequencies are shown in Table 2. The dominant and common species in them are Achnanthes lanceolata, Cocconeis placentula, Cyclotella meneghiniana, C. stelligera, Cymbella ventricosa, Diploneis ovalis, Meilosira distans, M. granulata, Synedra ulna, and all 'species show fresh v/ater forms. It may be sure that diatoms of this assemblage had lived in both stagnant and running water. From these results, the sediments containing this assemblage seem to be settling at the bottom of marsh and a river.

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Writers found many holes made by boring action of Parapholas quadrizonata on the shell surface of Crassostrea gigas, which built up a reef in situ in the upper part of the Kamiiwahashi formation in the environs of Yato-machi, Chiba City. The reef is 2 m in the thickest part and is spread horizontally in the distance of 50 m about. And it is composed of a single species, which is Crassostera gigas (THUNBERG). At the higher horizon than one-third of thickness of that reef, they could find many shells of Crassostrea gigas having holes made by Parapholas quadrizonata. Number of holes found on a single specimen of the former becomes larger as it ascends to the upper horizon of the reef, however the mean value of their number is about five to a sigle specimen. In the middle part of the reef, they found Trapezium (Neotrapezium) liratum (REEVE), Batilaria zonalis (BRUGUIERE) and B. multiformis (LISCHKE), which were buried in the silt cementing shells of Crasssostrea gigas. And in the upper part of the reef, they found Anadara (Tegilarcd) granosa (LINNAEUS), Cyclina orientalis (SOWERBY) and Saxidomus purpuratus (SOWERBY), all of which have two valves closed. Considering from writers' observation about the occurrence of the above-cited molluscs, they discussed paleoecology of Parapholas quadrizonata, which had been living in the tidal zone of the depth of the Paleo-Tokyo Bay during the deposition of the upper part of the Kamiiwahashi formation as follows. The larvae of Parapholas quadrizonata were scattered in the sea water, and some of them attached to the shell surface of Crassostrea gigas at the time when the latter had grew farely larger. As the former didn't drill through to the inner surface of the latter, and the openning of their holes often toward to the free side of the openning action of two valves of the latter, they assumed that these two species had the relation of mutualism. At the later stage of the growth of the reef, muddy sediments piled on this reef within short times and stopped the more development of the reef.

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The Hikami Granitic Complex, which extends for about 8 km E-W and 14 km N-S in the Southern Kitakami Mountains, northeast Japan, is petrographically described in detail. The Complex is petrographically divided into two granitic masses, namely A and B. Mass A mainly consists of tonalite to granite. Although the author subdivided this mass into three sub-facies, I, I' and II, according to rock facies and lithologic characters, most rocks are revealed cataclastic in texture and have undergone extensive hydrothermal alteration. Weak flow structure is characteristic throughout this mass. No contact effect on the country sedimentary rocks is apparent. The granitic mass A occupies more than two-thirds of the exposed surface of the Complex and is surrounded by Palaeozoic and Mesozoic sedimentary sequences. The Upper Carboniferous Nagaiwa series is obviously intruded by the granitic mass A in the studied area. The Ono type granite, which is petrographically equivalent to the granitic mass A, intrudes into Lower Permian rocks (Ishii et al,, 1960). The granitic mass B consists of tonalite to granite and includes the Tsubonosawa Metamorphics. It is lithologically subdivided into two subfacies and has conspicuous flow structures. Granitic rocks of the mass B are protoclastic in texture, and rarely unaltered. The mass B intrudes into the Upper Permian Toyoma series and also into the granitic mass A, while no contact effect by these granitic rocks is apparent in the host rocks. On the contrary, both the Toyama series sedimentary rocks and the granitic mass B are thermally metamorphosed by the Kesengawa type granodiorite, another granitic mass, of Middle Cretaceous age. Although the mass A is revealed as an intrusion of early Permian age, pebbles apparently derived from granitic rocks of this mass are frequently found in Middle to Upper Silurian (Kawauchi and Takainari Series) and in Lower Devonian (Ono ser.) sedimentary strata. These conflicting observations possibly signify that the granitic mass A is once was the basement of the pre-Middle Silurian stratified formations. Afterwards the mass A was partially remelted and its product (mass B) intruded into Upper Permian formations with the almost concomitant uplift of the remaining solid granitic mass A.

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