| 1887 Challengeria tridens - Haeckel p. 1651; not figured |
| 1899 Challengeria tridens - Cleve p. 28; not figured |
| 1900 Challengeria tridens - Jørgensen p. 90; not figured |
| 1901 Protocystis tridens - Borgert p. 29; fig. 33 |
| 1905 Protocystis tridens - Jørgensen p. 141; not figured |
| 1974 Protocystis tridens - Bjørklund fig. 9 |
| 1976 Protocystis tridens - Bjørklund pl. 12, figs. 1-3 |
