siphonacejE. 245 



cheria, named in honour of the Eev. M. Yaucher, a Gene- 

 vese botanist. 



Only three of the British species of this genus are 

 marine, the remainder grow in fresh water. They are 

 all insignificant, and cannot be easily preserved. The 

 process of development and fertilization of their zoo- 

 spores is, however, very curious, and has been carefully 

 studied and described at great length by Pringsheim. 



Vaucheria sub marina. The submarine Vaucheria. 



This species is figured and described in Berkeley's 

 Gl. Br. Alg., p. 24, t. 8, and the same figure and 

 description are given in the ' Phycologia Britannica/ 

 The description is as follows : — " Plant growing in dense, 

 fastigiate masses in muddy spots, covered by the sea at 

 every tide. Threads far slenderer than in Vaucheria 

 dichotoma, stained below by the mud, above dark-green, 

 forked ; the branchlets generally somewhat strangulated 

 just above their insertion ; the main stem clothed, above 

 the part where the branchlet is given off, with numer- 

 ous, almost sessile, more or less ovate, or lanceolate 

 coniocystse, which are pointed, at first entirely green, 

 but eventually with a pellucid border. One single in- 

 stance occurred in which the fruit consisted of two, 

 placed end to end." 



Vaucheria marina. The marine Vaucheria. 



Fronds growing in tufts or singly, an inch or two high, 

 sparingly, forkedly branched, slender. Fructification in 

 pear-shaped, lateral sporangia. 



This plant grows on mud, etc., between the tide- 

 marks during summer, and is annual. When fresh it is 



