The age composition of 101 individuals of Oguranodonta ogurae, which were collected in a small pond at Hirakata City, Osaka Prefecture in the late autumn of 1998, was determined by examination of the annual gorwth-interruption lines. Individuals with 5 growth-interruption lines (i. e. 6 years old) were most abundant, and there were only 5 individuals younger than 5 years old. The scarcity of young individuals may be due to the heavy drought occurred in the summer of 1994. Based on the assumption of the stable age distribution, a life table was estimated. The estimated generation time was 6.3 years.

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オグラヌマガイの妊卵期, 幼生の放出時期, 抱卵数, 幼生のサイズについて模式産地である, 大阪府枚方市楠葉の淀川ワンドで調べた。雌は2月には妊卵し始め, 4月にはグロキディウム幼生となった。幼生の放出は4月下旬より始まり, 大部分は5月中旬に放出は完了するが, 一部の雌は8月まで幼生の放出を続けるものと思われた。抱卵数は76, 000∿1, 210, 000, グロキディウム幼生の平均の殻長は0.258 mm, 平均の殻高は0.293 mmであった。従って, オグラヌマガイは夏繁殖の種であると考えられた。

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　This study aimed to examine the situation of ski clubs in junior high schools and high schools with a transition to the local communities of club activities, and organize issues related to the transition to the local communities of ski club activities. The research method was based on data published by the Japan Junior High School Physical Culture Association, All-Japan High School Athletic Federation, and Ski Association of Japan, to determine annual changes in junior high school and high school ski club students. The percentages of public and private schools participating in the 59th All-Japan Junior High School Ski Competition and the 71st All-Japan High School Ski Competition held in the 2021/2022 season were also investigated. The results showed that the number of junior high school and high school students who were members of ski clubs, and the number of students registered with the Ski Association of Japan showed a significant downward trend. The ratio of public schools to private schools in the All-Japan Junior High School Ski Championships and All-Japan High School Ski Championships showed that private schools tended to have more athletes in the Southern Kanto and Kinki regions, suggesting that the economic situation of families in urban areas has an impact on the number of athletes. As for the transition to the local communities of ski club activities, there are few obstacles to the transition of junior high school ski club activities because Alpine ski coaching for junior high school students is provided by local clubs, youth sports teams, prefectural ski federations, and professional coaches. However, the following issues were identified during the transition to local communities: “club management funds,” “securing and training instructors,” “improving instructorsʼ treatment,” and “ensuring a continuous environment for activities.”

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