再び北九州市立自然史博物館に寄贈されたイノセラムスとアンモナイト

抄録

This is to record the donation of the two large specimens of bivalve and ammonite from Mr. Toshio Shimanuki to the Kitakyushu Museum of Natural History. One is the left valve of Inoceramus (Inoceramus) iburiensis Nagao et Matsumoto from the Obira area of northwestern Hokkaido (Pl. 1, Figs. 1–4). It shows the characters which confirm the recently given redefinition and diagnosis of the species (Matsumoto, 1981) and also supplement certain points. The other is Fagesia spheroidalis Pervinquière from the eastern coast of Cape Soya, northern Hokkaido (Pl. 2, Figs. 1, 2). It is similar to an example from the Oyubari area of central Hokkaido described by Matsumoto & Muramoto (1978), but represents a more advanced stage of growth. A minor difference in the size of umbilicus from the lectotype from Tunisia is regarded as a variation. Remarks are given on the palaeobiogeography of Fagesia (see Text-fig. 3).

As an appendix a note is described, with T. Miyauchi, on the biostratigraphy of the Cretaceous strata exposed on the eastern coast of Cape Soya (Text-fig. 4). The Fagesia bearing bed is distinctly below the prolific part of the Zone of Inoceramus hobetsensis and probably assigned to the upper part of the Lower Turonian.