Third Group.—The floating power is due to the presence of air-bearing tissue in the seed-tests or fruit-coats.

Section I. The buoyant tissue occurs at the outside or forms the periphery of the seed or fruit. Unless otherwise indicated the fruit is implied in the list below.

Additions of shore-plants from Malaya and tropical America mostly given in Schimper’s work on the Indo-Malayan strand-flora.

Note.—Here belong a species of Vitex, probably V. agnus castus, the fruits of which occur in the stranded drift of the Sicilian beaches, and also the British littoral shore-plants, Cakile maritima, Crithmum maritimum, Matricaria inodora, and Scirpus maritimus.

Section II. The buoyant tissue forms a layer inside the hard test of a seed or inside the shell of the “stone” of a drupaceous fruit, and to this cause the floating power is mainly or entirely due.

Note.—I have followed Schimper in respect to Pandanus, but it might be by some placed in the first section of this group.