Type species: Eschara polymorpha Reuss, 1864
Often considered a subjective synonym of Bracebridgia.
This genus includes the species:
| Poristoma incisa | Canu, 1907 | Paleogene Eocene Ypresian-Lutetian | France |
| Poristoma magniporosa | Canu & Caillot, 1932 | Paleogene Eocene | France |
| Poristoma perlata | Canu & Caillot, 1932 | Paleogene Eocene | France |
| Poristoma polymorpha | (Reuss, 1864) | Tertiary | Europe |
| Poristoma polymorpha costulata | (Canu & Bassler, 1920) | Tertiary | USA |
Harmer notebook - entry for Poristoma
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