Diatom fossil analysis was performed to determine the depositional ages of the Miocene Noda and Fukuda formations in the eastern part of the Hiki Hills and the Miocene Arakawa Formation in the southwestern part of the Yoshimi Hills, which had problems on their stratigraphy and depositional ages. This study revealed that diatom fossils correlative to the early Middle Miocene diatom zone NPD4A (Denticulopsis lauta Zone) were found in the Noda Formation in the eastern part of the Hiki Hills, which was previously thought to be of late Middle Miocene. In addition, diatom fossils of the zones NPD4A, NPD3A (Crucidenticula kanayae Zone), and NPD3B (Denticulopsis praelauta Zone) were identified from the Arakawa Formation in the southwestern part of the Yoshimi Hills. Furthermore, diatom fossils of zone NPD4A were found in a sample of the Fukuda Formation in the eastern part of the Hiki Hills, but this sample is considered to be a part of megaclast in submarine debris flow deposits. Considering overall the results of previous studies and this study, the Noda Formation can be included in the Arakawa Formation in the western part of Hiki Hills. The Fukuda Formation can be correlated with the Ichinokawa Formation in the western part of Hiki Hills.

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Paleoparadoxiidae is the representative mammal fossil of Japanese Miocene. This paper presents the fossil records of Paleoparadoxiidae in the possession of “Fossil and Natural experience hall of Higashimatsuyama city”. There are twenty specimens from eight localities of Saitama prefecture were studied until 2015. Among these, thirteen specimens are known from one locality of Kuzubukuro Higashimatsuyama City. Since “Fossil and Natural experience hall of Higashimatsuyama city” opened in 2016, twenty-two specimens have been collected to date. Among these, Paleoparadoxiidae teeth identified upper P4, M2 and M3, and lower P1, P4?, and M2. In particular, upper P4, Lower P4 and M2 are the first report at Kuzubukuro. The number of specimens from Kuzubukuro is the largest number of Paleoparadoxiidae specimens reported from a single locality in the world. Because additional specimens are expected to be obtained in the future, these specimens could be ideal for studying morphological variations in molar teeth.

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I investigated the species composition and characteristics of cavity-nesting bees and wasps flying to the exterior walls of Saitama Museum of Natural History and the bamboo trap-nests set up on the site. As a result, I found 39 species on the exterior walls, and 29 species in the bamboo trap-nests, with the majority being cavity-nesting bees and wasps, and parasitoid wasps. Notably, Vespidae, Crabronidae, and Chrysididae were high diversity, but Megachilidae and Pompilidae were low diversity. There were few common species between the exterior walls and the bamboo trap-nests, and the species composition on the exterior walls was distinctive. Bees and wasps, and parasitoid wasps tended to fly to the sunny exterior walls. Although the exterior walls are not wooden buildings that have been known to be nesting sites for cavity-nesting bees and wasps, they are thought to be used as nesting sites.

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