Notes on Some Tertiary Non-Marine Mollusca from North Nippon

Abstract

1) Six new localities of Viviparus jimboi SUZUKI were found in the Oligocene Isikari series in the Province of Isikari, Hokkaido (Pl., 5(2), figs., 4-6)., 2) Among the thiarids from the Isikari series and the Uryu group in Hokkaido, the following three forms were distinguished., Semisulcospira fiscina (YOKOYAMA):- Thiara fiscina YOKOYAMA, 1932, Journ., Fac., Sci., Imp., Univ., Tokyo, ser., 2, vol., 3, pt., 6, p., 237, pl., 1, figs., 2, 3., Semisulcospira fiscina SUZUKI, 1941, Journ., Fac., Sci., Imp., Univ., Tokyo, ser., 2, vol., 6, pt., 2, p., 22, pl., 1, figs., 5-8., Melanoides (Semisulcospira) fiscina OTATUME, 1942, Journ., Geol., Soc., Japan, vol., 49, p., 586, p., 162, pl., 10, figs., 9-20., Occurence: Isikari series and Uryu group., Semisulcospira fiscina yokoyamai, n., subsp., ;- Semisulcospira fiscina SUZUKI (non YOKOYAMA, 1932), 1941, loc., cit., pl., 1, fig., 5., Melanoides (Semisulcospira) fiscina OTATUME (non YOKOYAMA), loc., cit., pl., 10, figs., 7, 8., Compared with S., fiscina s., s., this shell is narrower, having the much weaker longitudinal ribs., Occurrence: Isikari series and Uryu group., Melanoides otatumei SUZUKI, n., sp., :- Thiara fiscina OTATUME (non YOKOHYAMA), 1942, loc., cit., p., 162, pl., 10, figs., 1-6., This species is distinguishable from Semisulcospira fiscina s., s., and S., fiscina yokoyamai by the somewhat larger and narrower shell, the higher spire with straight outlines, the lower last whorl, and the more indistinct longitudinal ribs which are almost obsolete on the lower part of each whorl., The general outline of this shell may assure its reference to the genus Melanoides, though its aperture as usually seen in Semisulcospira and rather rare in Melanoides remarkably protruded downward beyond the base., Holotype: Pl., 10, figs., 1a-c (OTATUME, 1942)., Paratypes: Pl., 10, figs., 2-6 (OTATUME, 1942)., Occurrence: Isikari series., 3) Two new localities of Margaritifera perdahurica (YOKOYAMA) were found in the Isikari series in the Province of Isikari, Hokkaido (Pl., 6(3), figs., 1, 2)., 4) A specimen obtained from the later Oligocene Urahorp group in the Province of Kusiro, Hokkaido, appears to be referable to the genus Lamprotula, though it is too imperfect to make an exact identification (Pl., 6(3), fig., 7)., It is an internal mould of the left valve and is ovate in outline with the beak at the anterior extremity and the strong hinge-plate., It bears some resemblances to L., paihoensis KING, L., paihoensis minor LEROY, L., fibrosa (HEUDE), L., nojimensis UEJI and L., simanensis SUZUKI (MS), but the antero-ventral corner is not so protruded and the hinge-plate is not so strong as in the other forms., It is very interesting that a Tertiary shell which is closely related to Lamprotula occurs in Hokkaido., 5) Judging from the external features of the shell, Unio kobayasiensis OTUKA from the Early Miocene Yotuyaku series in Iwate-ken (Pl., 5(2), figs., 3a, b) may belong to the genus Inversidens., It differs from the recent Nipponese I., reiniana (KOBELT) in having the much higher anterior part and the more straight ventral margin., Furthermore, it has the anterior part much shorter than in the other recent forms of the genus as well as in I., isikariana SUZUKI from the Isikiri series in Hokkaido., 6) A new locality of Lanceolaria pisciformis (YOKOYAMA) in the Isikari series in Hokkaido was noted., 7) A strongly deformed specimen of Lepidodesma septemtrionale SUZUKI was obtained from the Early Miocene Estoru coal-bearing formation in the Nayosi coal-field, South Karahuto (Pl., 5(2), fig., 7, pl., 6(3), fig., 3)., It agrees well with the holotype specimen (a young shell) from the Isikari series in Hokkaido and some specimens from the Dui coal-bearing formation in the Dui coal-field, North Sachalin (Pl., 6(3), figs., 4-6). [the rest omitted]