In general the fauna of an isolated island is interesting in the points of ecological and geographical views. Okino-shima (Lat. 34° 14' N, Long. 130" 06' E) situated in the Japan Sea, 74.9 km off Fukuoka City, is an islet about 4 km in circumference (Fig. 1 ). The whole islet consists of a mass of mountains surrounded by cliff. There is, however, only one gravel shore where the wharf is constructed at southern edge of the islet. A chain of four peaks runs from west to east along the major axis of the islet. A lighthouse stands above the summit of Mt. Ichino-take and two old batteries of war time remain at the summit of Mt. Shira-take and another place (Fig. 2 ). The whole islet belongs to the precinct of the Munakata Shrine. As the permanent residents, one Shinto priest and another lay man dwell in the shrine yard and besides them three lighthouse personnels work comming by turns. Some fishermen stay at some huts near the wharf in spring and winter fishing seasons. At the time of this survey, a number of laborers had been boarding together at some rude cabins for the purpose of repairing work of the wharf. As above mentioned, owing to the taboo of faith, difficulty of communication or strategic importance, the islet has been isolated from Kyushu for a long time. Therefore, influence of human power has not almost been imposed upon the islet and the vegetation consisted of evergreen broad-1 aved trees shows an appearance of virgin forest. Ikeda & Yasumoto (1933) and Ohshima (1934 b) reported on chiefly shore animals, and Kuroda & Uchida (1959) described a new form of shrew, Crocidura suaveolens okinoshimae which is also interesting geologically, from the islet. We stayed at the islet to study the fauna from July 24 to 28, 1958. In this paper, has been described only the peculiarity of vertebrate fauna represented by the black rat, streaked shearwater and endemic lizard. The results obtained are as follows : Mammalian fauna is very poor as in the case of other islets. Murine fauna contains only one species, Rattus rattus (Linnaeus) all over the islet. The rats inhabit not only in the district of residence near the wharf and lighthouse (Fig. 2-sts. B and C ; Figs. 3 and 4), but in the forest (Fig. 2-sts. A, D and E ; Figs. 5-8). In addition to this, the population density seems to be relatively high. By the examination of the contents of stomachs, it became clear that the rats in the district of residence were semi-wild. As to the feeding habits, considerable difference was found between the semi-wild and the wild lives (Table 1 ). The rats were considered to be just after entrance to the breeding season judging from the inspection of their genital organs and age-constitution of captures. Such a peculiarity of murine fauna is attributed to simplicity of ecological environment and geographical condition which prevents from invasion of the Norway rat, Rattus norvegicus (Berkenhout) to the islet. Besides this, an endemic shrew was reported as above mentioned. One species of Chiroptera was found by Ikeda & Yasumoto (1933), specific name being unknown. Carnivora does not inhabit in the islet. Puffinus leucomelas (Temminck) which is the most dominant species of birds in the islet, inhabits at north-western and south-western parts of the islet (Fig. 9). The habitat is closely connected with the soil and the topography of the land. The birds were just in breeding season at the time of this survey, and either of the parents sat on an egg in the nest alternately day and night. It is very interesting that the birds inhabit sympathetically together with the black rats at the same habitat. This phenomenon can b. attributed to noncompetition for foods between both species. Only one endemic lizard is fairly numerous as reptile, and no amphibian species is found in the islet. This agrees with Ohshima's report. This seems to be attributed to environmental factors, such as spray of sea-water coming up to the top of mountain at the time of typhoon, together with the condition that no water puddle is made when it rains, the slope being very steep. The endemic lizard was identified as Eumeces latiscutatus latiscutatus (Hallowell) by Prof. Koba of Kumamoto University, though he noticed some differences between common and endemic ones as mentioned below. Measurements and scale character of six endemic lizards are shown in Table 2. The endemic lizards were measured more than 200 mm in total length (Fig. 10), and individuals which have 28 scale rows were found in fairly abundance (Table 3). In the common lizards, the first supraocular does not come in contact with posterior loreal, because the first superciliary which is more than twice the size of the last superciliary keeps touch with prefrontal (Fig. 11-A). On the contrary, in the endemic lizards the first superciliary which is less than twice the size of the last one does not come in contact with prefrontal (Fig. 11-B). It is desired to study further on this point basing on many specimens.
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