About 90 years ago Edmund von Mojsisovics (1888) described several species of Daonella and Monotis together with some ammonites from the Triassic strata of Sakawa basin of Shikoku and a few other areas as the first report on Mesozoic molluscan fossils from Japan. Since then, many paleontologists and stratigraphers have contributed to the description and classification of Japanese Mesozoic Bivalvia. Approximately 860 taxonomic names of species-group have been used in these studies, of which about 770 are regarded here as valid (see Table 1). The majority of them have been regarded as endemic species and subspecies, the known distribution of which is restricted to Japan and its adjacent areas. A number of characteristic genera and subgenera also were proposed through these studies, and they often seem to be important for the taxonomic and evolutionary considerations of this class from the international viewpoint.

More than 250 scientific papers were devoted to the description and classification of esozoic Bivalvia from Japan and its adjacent areas. They appeared in many periodicals from various societies and institutions. Unfortunately many of them have a restricted circulation and are sometimes hardly accessible even by domestic students. In recent years foreign paleontologists have frequently treated and discussed Japanese Mesozoic Bivalvia in their comparative or comprehensive taxonomic studies (e.g., Cox et al., 1969). However, some studies by Japanese authors were overlooked, and in some cases taxonomic positions and diagnostic characters of endemic taxa were misinterpreted. This inconvenience appears to have arisen from the want of communication between Japanese and foreign students, although it must be partly due to such unfavorable circumstance as insufficient description, inadequate illustration, our unfamiliar writing of foreign languages and taxonomic proposal on too poorly preserved material. Because taxonomy must be an international science, this status is deeply regrettable.

Although some of these describers were already retired or deceased, most of the type specimens are now fortunately kept at various institutions in Japan. About a half of them are registered and actually observable at the University Museum, University of Tokyo, to which I am now attached.

The main purpose of this study is to summarize the present status in the classification of fossil Bivalvia hitherto described from the Mesozoic of Japan and its adjacent areas (Saghalin, Kurile, Korea and Formosa) and to offer a handy manual for further investigation. The systematic catalogue in this article treats such basic information about every taxon as synonymy, references, primary type specimen (holotype, syntype, lectotype or neotype) and its repository, type locality, known vertical range and geographic distribution, Omitted are works such as faunal lists in stratigraphic papers with neither description nor illustration, picture books with no original illustration, guide books for excursions and various unscientific accounts. Specific and subspecific names are revised and modernized as far as possible, but proposals of new taxonomic names and new designation of lectotype specimen are avoided except in a few special cases. In the annotated list of genera and subgenera proposed on the Japanese materials are given their diagnostic characters and other basic information together with some comments on their taxonomic positions.

Illustrations are, of course, often as valuable as, or more informative than, verbal descriptions. It is, however, impossible to illustrate all the type specimens in a limited space, because they are too numerous. Only selected specimens of about 90 important species (including most of the type-species on which new genera or subgenera were proposed) are shown in the annexed plates. Most of them are original type specimens, but some are better preserved topotype specimens, the taxonomic identification of which is undoubted. Photographs were newly prepared (Plates 1-8) except for several reproduced from original illustrations (Plates 9, 10).