260 The Scottish Naturalist. 



other species. The capsular fruit, or oogonia, are spherical, and 

 sessile on the side of the erect thread (see Fig. i), and occur often 

 on the same tuft with the antheridia, but on distinct threads. I 

 have already issued this plant with both kinds of fruit in my 

 Fasc. Alg. Brit. rar. II. The fruit in this species, as in most 

 others of the marine Vaucherice, is found from August to November. 



Harvey's figure of V. velutina Ag., Phyc. Brit., t. 351, is con- 

 sidered by Dr. Nordstedt to represent two species ; the right-hand 

 figure at the base, with sessile oogonia, he refers to V. spJicerophora, 

 Nordst, the left-hand figure to V. Thuretii, but as Harvey does 

 not figure the antheridia, it is impossible to decide this point. 



Having thus disposed of the marine species already described 

 as British, I may venture to translate, for the benefit of those 

 British algologists to whom the scattered literature on the subject 

 is not easily accessible, Dr. Nordstedt's classification, as given in 

 the Bota?iiska Notiser, 1879, and afterwards to describe more in 

 detail the species which he has discovered during his recent flying 

 visit to this country. The additional species likely to be found in 

 Britain by those that have time and will take the trouble to search 

 for them, may thus be described and illustrated : — 



VAUCHERIA. 



I. Antheridia sessile, not separated from the thallus 



by a short empty cell. 



A. Tubuligerae. Antheridia not hooked at the end, elongate, 

 cylindrical or barrel-shaped, with an apical pore ; red pigment- 

 body not collected in the middle of the mature oospore. 



(a.) Oogonia globular. 



1. Vaucheria dichotoma Ag. — Dioicous, oogonia sessile, hori- 

 zontal ; antheridia ovate, conical, horizontal. (Fig. 1). 



2. V. Thuretii, Woronin. — Monoicous ; oogonia sometimes 

 stalked, sometimes sessile, oospore filling up only the upper 

 rounded portion of the oogonium. (Fig. 2). 



II. Antheridia separated from the thallus by a short 



empty cell. 

 A. Androphoreae. Antheridia numerous and hooked, ses- 

 sile on an enlarged chlorophyll cell or androphore, which is 

 attached by a short empty intervening cell to the side of the 

 thallus. 



