Frontal ridge, [260]
Frullania, inhabited by Rotifers, [227]
Fulcrum, in Rotifers, [210]
Funicular tissue, [471]
Funiculus, [469], [471], [472], [499], [501]
Furcularia, [216], [224], [226]
Gamble, on Platyhelminthes, [3] f.;
on Mesozoa, [92] f.
Gammarus, Rotifers attached to, [227]
Gapes, cause of, [144]