"野尻湖層産カワニナ胎児殼化石について : 現生カワニナとの比較研究 "On the fossil embryonic shell of Semisulcospira libertina (GOULD) (Mesogastropoda: Pleuroceridae) from the latest Pleistocene Nojiri-ko Formation, Nagano Prefecture, Central Japan: A comparative study of recent and fossil Semisulcospira".