Protoclepsydropsis kidstoni (Bertrand) Hirmer is a small fossil fern with a slender stem about 3 mm. diameter bearing petioles of a Clepsydropsis type in a ⅖ phyllotaxy.
Larger isolated Clepsydropsis petioles from the same rocks probably belong to a larger related plant. In these the petiolar bundle is sometimes oval in cross section with protoxylem groups nearer one tangential surface. Occasionally roots are borne on these petioles. A resemblance to the petioles of Asterochlœna laxa Stenzel is pointed out.