| Amemiyaia pacifica Kato, 1944 | 1944 or earlier | | | |
| Hoploplana ornata Yeri & Kaburaki, 1918 | June 1937 | | | This splendid Hoploplana is commonly found on the undersurface of stones between the tidemarks at Zuirin-ji. |
| Planocera reticulata (Stimpson, 1855) | June 1937 | | | This species is very common in this district. |
| Pseudostylochus meridialis Kato, 1938 | June 1937 | | | Two specimens were collected under stones in a muddy beach near Zuirin-ji. |
| Pseudoceros memoralis Kato, 1938 | Jun 1937 | | | two individuals living on the undersurface of stones below the medium tidemark at Tusi-jima. |
| Prosthiostomum auratum Kato, 1937 | Jun 1937 | | | single specimen found at Zuirin-ji. |
| Prosthiostomum vulgaris Kato, 1938 | Jun 1937 | | | widely distributed collected at Tomioka. |
| Prosthiostomum sonorum Kato, 1938 | Jun 1937 | 18.2 m | | A single specimen of this species was collected by the dredge along with some corals from a depth of 10 fathoms off Tomoe-zaki. |
| Cryptocelis amakusaensis Kato, 1936 | 1937 or earlier | | | common on the sandy beach in the vicinity of the Laboratory during spring and summer, and often attacks the living periwinkle, Umbonium moniliferum to put to death. |
| Notoplana delicata (Yeri & Kaburaki, 1918) | 1944 or earlier | | | |
| Notoplana serica Kato, 1938 | 1937 or earlier | | | |
| Hoploplana ornata Yeri & Kaburaki, 1918 | 1944 or earlier | | | Tomioka, Amakusa. |
| Planocera multitentaculata Kato, 1940 | 1944 or earlier | | | Usually found together with Planocera reticulata. |
| Cestoplana marina Kato, 1938 | 1944 or earlier | | | Tomioka, Amakusa. A single specimen. |
| Pseudoceros sagamianus Kato, 1937 | 1944 or earlier | | | Found on Gelidium. |
| Prosthiostomum grande Stimpson, 1857 | 1944 or earlier | | | |