Morphological change in growth process is a phenomenon restricted to organism and it is important to clarify the mechanisms of morphological change and factors affecting it. The purpose of this study is to investigate the factors controlling morphological change based on theoretical considerations of growth process and biometrical analysis of shell form. In general, since the growth rate of an organism is considered to be proportional to its size, the weight of organisms is expressed as an exponential function of its volume. Furthermore, introducing a concept of density, it is expected that the change of density with growth is either proportional or inversely proportional to the volume of organisms. Biometrical analyses of shell form were carried out in order to test the result of theoretical con sideration. The specimens use were fossil samples of Anadara kogachiensis from the Pliocene of Motobu Peninsula in Okinawa Prefecture. The relative density and weight of shell were calculated from the measured value of shell and the variation of density throughout growth process was computed. The result shows that the density variation has three phases; it decreases gradually in early stage of growth, then increases in middle stage. This result indicates that the morphology of shell is closely related to a function of organism which tries to keep the density constant and also suggests that gravity is an important external factor affecting shell morphology.

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The basal part (Gotanda conglomerate) of the Ogawamachi Group (Middle Miocene) comprises large pebbles, sometimes large boulders, of pultonic and metamorphic rocks, from which the following rock-types are discriminated under the microscope: granite, granodiorite, banded quartz diorite, diorite, amphibole schist, cordierite-biotite gneiss and biotite quartzo-feldspathic gneiss. Of these pebbles,cordierite-biotite gneiss is safely identified with the gneiss of the cordierite zone of the Ryoke belt and granitic rocks are mostly similar to some Ryoke granites. Moreover, TAKEI and KOIKE (1977) have found a small outcrop of the gneiss to the east of Ogawa-machi. From these facts, it is certain that the Ryoke belt was widely exposed to the north of the Kanto mountains before the Middle Miocene. In the northern Kanto mountains, the pelitic metamorphic pebbles in the Cretaceous system are exclusively biotite-schist. On the contrary, they are cordirite-biotite gneiss in the Middle Miocene series. Accordingly, the Ryoke belt in this area would continue to be raised at the time from the Cretaceous to the Middle Miocene. Then, the belt was changed into a subsiding zone during a time of the Miocene, and was largely covered by the Miocene sediments.

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A Significant structural belt termed as the "Koshidai-Takabo-Daiyu-in" one, was found in low-grade metamorphic terrain (the Gozaisyo and Hitachi metamorphics) by our researches during 1965-1977. It runs from Daiyu-in (Hitachi City) via Takabo-yama (Kitaibaragi City) to Koshidai-Takanukida villages (Higashishirakawa-gun, Fukushima Pref.) and hereby is estimated to be 70-80 km in its extension. Several diaphthoritic bodies including a small amount of alumino-silicate porphyroblasts, especially kyanite-andalusite ones, were found within the belt. The "Takabo metamorphics" is a kind of diaphthorites, which were firstly paid an attention to these petrological significance by SUGI (1938). A significance of unearthings of the "Koshidai-Takabo-Daiyu-in structural belt" and the alumino-silicate bearing diaphthoritic bodies leds to the conclusions that this belt is not a simple fracture belt but the structural one in a synthetical sense, in which the metasomatized uplifting bodies with alumino-silacate porphyroblasts, hydrothermal-metasomatic altered rocks with metal mineralization of copper and manganese and various acidic plutonics are distributed. These events seem to be related to migmatization activities taken place in certain parts of the "Takanuki metamorphics", probably of the Indosinian Orogeny. In this paper certain significances of the structural belt, kyanite-andalusite porphyroblastic diaphthorite and the "Takabo metamorphics" are mentioned.

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Ponape Island, the largest island of the East Caroline Islands, is located at Lat. N. 6°55′ and Long. E. 158°15′. The author obtained a xenolith of anorthositic gabbro at the Fall Tokiwa of the River Panparipi on December 13th, 1971. The host rock is dark gray and compact olivine basalt. Olivine phenocrysts are less than 1% in mode. Olivine nodules, ellipsidal and drop shape, are striking. The xenolith, hypidiomorphic-granular to allo-triomorphic-granular, shows cataclastic texture and granulation, and is composed of plagioclase, augite, olivine, ilmenite and secondary minerals. The xenolith has some characters of metamorphic rock and is not simple igneous rock. Concerning to the origin of this rock, the author considered this rock has the same origin as many massive anorthosites. Many massive anorthosites were formed in pre-Cambrian continental crust. Although there is not corresponding layer which has seismic wave velocity of 6.0 to 6.7 km/sec, the thickness of the crust is known as 15 to 20 km under the East Caroline Ridge. This value of the thickness is three to four times as thick as normal oceanic crust. The author suggest a possibility of the existence of pre-Cambrian continental crust under Ponape Island or the East Caroline Islands.

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