The characteristics of the megafossil assemblages in the Upper Yezo Group (Upper Turonian) in the lower stream of the Pombets, the tributary of the Ikushumbets, central Hokkaido are described in this paper, discussing their paleoecological and paleoenvironmental implications. The Upper Turonian sequence along the Pombets is represented by silty to fine sandy sediments with several thin beds of fine sandstone. Calcareous fine sandy nodules are predominate at various horizons, and some of them are rich in megafossils such as molluscs, fish and lobster, together with numerous drifted plant remains and amber fragments. The assemblages in the lower part of the Upper Turonian are characterized by the abundant occurrences of the collignoniceratids and Linuparus cf. japonicus (lobster), while those in the middle to the upper parts are rich in the heteromorph ammonites (especially scaphitids), desmoceratids and tetragonitids, with an elopoidid fish, Holcolepis sp. at two horizons. With respect to the species composition and diversity, the former assemblages are similar to those in the nearshore shallow-water facies in the Manji-Yubari areas, south of the Pombets area. In contrast, the latter ones suggest the transitional biofacies from the intermediate facies reflecting the outer shelf environment to the nearshore shallow-water one in the marine Upper Turonian sedimentary basin of central Hokkaido. Judging from the ecology of allied modern species to L. cf. japonicus and the Elopoidei, and the litho- and biofacies characteristics mentioned above, it is suggested that the fine sandy to silty sediments in the Upper Turonian of the Pombets area might have had deposited on the shallow sea bottoms of about 100 m depth (inner shelf) under the influence of warm currents. We also discuss some problems on sedimentary environments and habitat distributions of Nipponites and Madagascarites in Hokkaido in Turonian times.

The morphological works on the female genital structure of Hepialidae made by Bourgogne (1949), Stekol’nikov (1967), Mutuura (1972), Dugdale (1973) and Kristensen (1978) are reviewed and summarized. The confusion on the homology of 8th sternum and the origin of lamella antevaginalis are shortly discussed. The female genital structures of six hepialid species are described and illustrated. The terminology proposed by Kristensen is the most useful to describe this structure clearly. But, the term lamella antevaginalis is not adopted, because it was originally proposed for the female genital structure of Ditrysia.

Development of the caudal skeleton of Leiognathus rivulatus was examined and described. Caudal skeletons of 3 genera of the family Leiognathidae, Leiognathus, SecrJtor, and Gazza are compared. The following features of caudal skeletons are found to be characteristic in the Leiognathidae.

1) Loss of the second uroneural.

2) Enlarged first epural.

3) Fusion between the first and second hypurals, and between the third and fourth hypurals.

4) Oar-like flange of heamal and neual spines on fourth preural centrum.

Leiognathus and Secutor have very similar structure in the caudal skeleton. The caudal skeleton of Gazza differs from those of other genera in following characters: 1) trace of fusion between PU1 and U1 is recognizable (not in other); 2) hypuropophysis is parallel with the body axis (slanted toward posterodorsal direction in others); 3) neural spine and hemal spines of PU₅ are expanded (not in others).

An occurrence of a stegodont molar from Seiryukutsu-Cave in Hiraodai Karst Plateau is reported. The material, anterior three crests of ³DM, represents characteristics of molars of Stegodon orientalis Owen. It shows a presence of late Early Pleistocene deposits in this area. The molar is almost unworn with slight occlusal facets at the anterior two crests, and it indicates very young stage of the individual.