Individual numbers and gut contents of collembolans collected from 27 species of agaric fruit bodies occurring in a mixed forest of Pinus densiflora and Quercus serrata were studied. Most of the collembolans on the fruit bodies were Hypogastrura (Ceratophysella) denisana. The numbers of H. denisana relative to pileus size of the fruit bodies were significantly different among fungal species, and they did not correlate significantly with surface area of gills relative to pileus size, gill depth or distances between two adjacent gills.

　In basidiospores contained in the gut of H. denisana, three types were distinguished in the degree of deformation of the spores: intact, flattened, and hollowed and partly broken spores. These corresponded to morphological features of the spores at a higher taxonomic level. Most pigmented basidiospores kept their original shape, while hyaline, smooth ones were flattened. Hyaline spores with spines or tubercles were found intact, or hollowed and partly broken.

　Nematode-trapping fungi distributed in Okinawa Island, were isolated and identified, and the physical, chemical and biological factors in their distribution were analyzed. Eighteen species of fungi in five genera, including one unidentified species, were collected from across Okinawa Island. Arthrobotrys oligospora and Monacrosporium eudermatum were dominant species, followed by A. conoides and Stylopage sp. in order. Arthrobotrys javanica, Dactylaria effusa, M. lysipagum, and M. phymatopagum were newly recorded in Japan. These species showed specific distribution patterns according to the parent materials, depth, vegetation, pH and humus and calcium contents of the soil. Various calcium salts were added to Hopkins basal medium to examine the effect on hyphal growth, and all compounds except CaCl₂ and CaSO₄ were found to stimulate the growth of three nematode-trapping fungi out of five. In dual cultures of the 18 fungi from soils, M. bembicodes was strongly antagonized by Penicillium K1530B.