Umbonium ? sp.
| 1937. | Umbonium ? sp. |
| 1929. | Umbonium sp. |
| Condition: | Present |
| Taxonomy: | Mollusca: Gastropoda: Trochidae: |
| Geologic Time: | Cenozoic: |
| Otuka, Y., 1937a: The geologic age of the Tertiary formation near Hamada, Simane Prefecture, Japan. Japanese Journal of Geology and Geography, vol. 14, nos. 1–2, pp. 23–32, pl. 3. (Reference No. 0392) |
| Yokoyama, M., 1929a: Neogene shells from some provinces of Chugoku. Journal of the Faculty of Science, Imperial University of Tokyo, Section 2, vol. 2, pt. 8, pp. 363–368, pl. 70. (Reference No. 0496) |
 |
| Ichikawa, T., 1983, no. 9, p. 103. |
| Ichikawa, T., 1983, no. 9, p. 378. |
