Lyonsiella ( Simplicicordia ) trigonata (Yokoyama, 1922)
| 1973. | Lyonsiella (Simplicicordia) trigonata (Yokoyama, 1922) Paralectotype Oyama, K. 1973 p. 120, pl. 57, fig. 18 |
| 1954. | "Thyasira" trigonata Yokoyama, 1922 Paralectotype Taki, I. & Oyama, K. 1954 pl. 29, fig. 12 |
| 1922. | Thyasira trigonata Yokoyama, 1922 Syntype Yokoyama, M. 1922a p. 158, pl. 9, fig. 12 |
| Condition: | Present |
| Taxonomy: | Mollusca: Bivalvia: Verticordiidae: |
| Geologic Time: | Cenozoic: Pleistocene: |
| Horizon: | Imba Group: |
| Locality: | Chiba: Ichihara: Shito: |
| 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., 1922a: Fossils from the upper Musashino of Kazusa and Shimosa. Journal of the College of Science, Imperial University of Tokyo, vol. 44, art. 1, pp. 1–200 + i–viii, pls. 1–17. (Reference No. 0465) |
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| Ichikawa, T., 1983, no. 9, p. 141. |
| Ichikawa, T., 1983, no. 9, p. 208. |
| Ichikawa, T., 1983, no. 9, p. 277. |
