| 1973. | Cymatium (Monoplex) echo Kuroda & Habe Oyama, K. 1973 p. 36, pl. 9, fig. 3 PreviousNo: 22012 |
| 1954. | Cymatium (Monoplex) echo Kuroda & Habe Taki, I. & Oyama, K. 1954 pl. 38, fig. 16 PreviousNo: 22012 |
| 1924. | Triton (Simpulum) costatus (Born) Yokoyama, M. 1924a p. 17, pl. 1, fig. 16 PreviousNo: 22012 |
| Condition: | Present |
| Taxonomy: | Mollusca: Gastropoda: Ranellidae: |
| Geologic Time: | Cenozoic: |
| Locality: | Chiba: Tateyama: Numa: |
| Oyama, K., 1973: Revision of Matajiro Yokoyama's type Mollusca from the Tertiary and Quaternary of the Kanto area. Palaeontological Society of Japan, Special Papers, no. 17, pp. 1–148, pls. 1–57. (Reference No. 0411) |
| Taki, I. and Oyama, K., 1954: Matajiro Yokoyama's the Pliocene and later faunas from the Kwanto region in Japan. Palaeontological Society of Japan, Special Papers, no. 2, pp. 1–68, pls. 1–49. (Reference No. 0441) |
| Yokoyama, M., 1924a: Mollusca from the coral-bed of Awa. Journal of the College of Science, Imperial University of Tokyo, vol. 45, art. 1, pp. 1–62 + i–iii, pls. 1–5. (Reference No. 0471) |
  |
| Ichikawa, T., 1983, no. 9, p. 144. |
| Ichikawa, T., 1983, no. 9, p. 211. |
| Ichikawa, T., 1983, no. 9, p. 296. |
