Formica rufescens, [219].
—— sanguinea, [219].
—— flava, neuter of, [240].
Frena, ovigerous, of cirripedes, [192].
Fresh-water productions, dispersal of, [383].
Fries on species in large genera being closely allied to other species, [57].
Frigate-bird, [185].
Frogs on islands, [393].
Fruit-trees, gradual improvement of, [37].
—— —— in United States, [85].