ON THE JAPANESE SPECIES OF VICARYA

1. The genus Vicarya was established by D\u27ARCHIAC and HAIME upon Nerinea? verneuili D\u27ARCHIAC, a Miocene species from India.2. Discussions as to the generic value of Vicarya and as to its generic position have been given by K. MARTIN, W. H. DALL, W. D. SMITH, K. A. V. ZITTEL and recently by T. TAKEYAMA. Its position is now placed in the Potamidinae.3. The following forms are now considered as valid in the genus Vicarya, namely, ecocenica, verneuili, callosa, callosa japonica, callosa martini, callosa yokoyamai, yatuoensis and probably callosa semperi.4. Vicarya is a genus having species restricted in geographical distribution to the Far East, and ranging in time from the Eocene to Miocene, being best developed in the Lower or Middle Miocene, a time prior to its extinction which may be Upper Miocene, according to the usage of the term.5. In the Japanese Miocene are found the following forms, namely, callosa japonica, callosa yokoyamai, callosa martini and yatuoensis ; all are restricted to the Middle Miocene of Japan, and play an important role in the geological history and stratigraphical relationships of geographically isolated geological formations.6. The manuscript genus Vicaryella of T. TAKEYAMA is here defined and thus made valid ; the following species are now found to belong here, namely, tyosenica the genotype, nipponica, bacula and probably ishiiana.7. The habitat of both Vicarya and Vicaryella was one of brackish-water, at very shallow depths such as at the tidal zone, of warm water and particular nature.8. From the associated faunules of both Vicarya and Vicaryella, it is found that their stratigraphical importance is nearly equal.9. Keys to the species of both genera have been given in order to faciliate workers along this line.10. Descriptions and figures of all known species of both genera are given