47 



ALG.E FILIFORMES. 



FAMILY SIPHONED. 



Characters. Algae composed of a continuous branched and 

 cylindrical cell. Reproductive organs external. 



GENUS VAUCHERIA D. C. 



Char. Frond here and there occasionally inflated. Repro- 

 ductive organs of two kinds, consisting of capsules and 

 antherce or horns, lateral or terminal. 



Vaucheria D. C. in Yauch. Conf. ; Lyngb. 65. t. 19. 23. ; 

 E. B. 1766. 933.; Flor. Dan. t. 1724. 1727.; Grev. 

 Algae Brit. t. 19. Ectosperma Vauch. Conf. t. 2, 3.; 

 linger in N. A. N. C. xiii. p. 789. 140. ; Conf. Sp. 

 Dillw, 1. 15, 16. 47. 74. 



OF all the freshwater Alga, none are more interesting or 

 more curious than those which we are about to describe. It 

 was from a knowledge of the reproduction of this genus, which 

 was first clearly made known by Yaucher, in his excellent 

 work on the Alga, 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 entertain 

 the notion of sexes in this class of plants, a notion which 

 even now it is by no means easy in all cases to discard. 



The Vaucheria are first described in this work, because 

 amongst the freshwater Algae they seem to stand alone, exhi- 

 biting no distinct relation to any other genus of that division 

 of the Alga, 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 two 

 kinds, being composed of capsular bodies, and of filaments, 



