Thysanozoon nigrum Girard, 1851 | 1851 | | | east coast of Florida. |
Stylochus oculiferus (Girard, 1853) | prior to 1940 | | | Florida, North Carolina, rather rare. Found mostly on oyster beds. |
Euplana gracilis (Girard, 1850) | 1940 or earlier | | | Florida to Prince Edward Island, common. Habits.—Active, among seaweeds, hydroids, tunicates, etc., on pilings, also among old shells, littoral. |
Gnesioceros floridana (Pearse, 1938) | 1940 or earlier | | | Florida to Massachusetts, common in the southern part of the range. Habits.—Among sea^yeeds, quick, active, may swim to some extent. |