On June 24th, 1797 some magacerid bones were found at a hillside of Fukamachi, Kamikuboiwa, Tomioka City, Gunma Prefecture, and on July 7th of the same year natives excavate the site and gained antlers, jaws, vertebrate, scapula, limb bones etc.; they presented them to MAEDA, the feudal lord of the district. In November, 1798, a small stone monument of this discovery was built upon the hill. In the summer of 1800, Motohiro TANBA, head doctor of the TOKUGAWA family, kept a record of his description, illustration and determination of the materials. His manuscript is very accurate and now preserved in Hensyo temple in Kamikuroiwa. Choyokan Manpitsu written in 1811 by Tozan KAMAHARA mentioned this discovery. The bones had been stored in the house of MAEDA in Edo, but in 1933 Toshisada MAEDA donated all the materials to the Zyagu shrine in Nanukaichi, Tomioka City, and henceforward they have been kept perfectly as sacred treasures of the shrine. In April, 1959 Syuichi TSUGAWA visited the shrine and recognized the treasures as megacerid fossils of excellent preservation. In March, 1961, the writers visited the locality and verified the existence of the stone monument. The materials of this interesting discovery and history is the best specimens ever known in Japan of Sinomegaceroides yabei (Shikama) of late Pleistocene.
In order to make clear the geological development of the Japanese Islands, it is necessary to comprehend the geological histories of the adjacent areas. On these lines the recent knowledge on the Cambrian and Ordovician systems of the U. S. S. R. have been introduced by Kobayashi elsewhere in this journal. Silurian is a period of the oldest age of rock formations in Japan. On the Silurian system of China the present writer has already described its geological and geographical features. Here he intends to summarize the Silurian system in the U.S.S.R. from the literatures. Its description is made as follows: I. Introduction II. On the Guide books and Geological maps III. General Remarks on the Silurian System IV. Outline of the Silurian Stratigraphy. A. Lower Llandovery Stage, B. Upper Llandovery Stage, C. Wenlock Stage, D. Lower Ludlow Stage, E. Upper Ludlow Stage V. Summary on the Geographical Development References A distribution map of the Silurian system in the U. S. S. R is inserted on page 26. The Silurian zonation based on the graptolitic fauna is shown in form of a table in comparing with the Bohemian succession. The regional stratigraphy, igneous activity, Silurian paleontology and others will be outlined as the continuation of this paper.