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ALGiE FILIFORMES.

Family SIPHONEJE.

Characters. Algse composed of a continuous branched andcylindrical cell. Reproductive organs external.

Genus VAUCHERIA D. C.

Char. Frond here and there occasionally inflated. Repro-ductive organs of two hinds, consisting of capsules andantherce or horns, lateral or terminal.

Vaucheria D. C. in Vauch. Conf.; Lyngb. 65. t. 19. 23.;E. B. 1766. 933.; Flor. Dan. t. 1724. 1727.; Grev.Alga ; Brit. t. 19. Ectosperma Vauch. Conf. t. 2, 3.;Unger in N. A. N. C. xiii. p. 789. 140.; Conf. Sp.Dillw, 1.15, 16. 47. 74.

Of all the freshwater Algae none are more interesting ormore curious than those which we are about to describe. Itwas from a knowledge of the reproduction of this genus, whichwas first clearly made known by Vaucher, in his excellentwork on the Algce, the only monograph at the period in ex-istence devoted exclusively to the consideration of the fresh-water division of the tribe, that naturalists were led to entertainthe notion of sexes in this class of plants, a notion whicheven now it is by no means easy in all cases to discard.

The Vaucheria are first described in this work, becauseamongst the freshwater Alga they seem to stand alone, exhi-biting no distinct relation to any other genus of that divisionof the Algce, although to the genera Codium and Bryopsis,amongst the marine species, they manifest a close affinity.

The organs of reproduction of the Vaucheria are of twokinds, being composed of capsular bodies, and of filaments,