BRY0F3IS — CLADOPHORA. 



65 



the sea last August, and by the untiring exertions 

 of a few green sea-weeds the water has been 

 preserved bright and pure, even though inhabited 

 by all kinds of marine animals. 



Among the most useful, as well as the most 

 elegant of the sea-weeds used for this purpose, 

 is the little Bryopsis plumosa ; see plate d, fig. 3, 

 This brilliant and delicate little plant is common 

 enough, and may be found in the pools left by 

 the retiring tide, where it adheres to their rocky 

 walls. The colour of the plant is a very bright 

 green, and its form is so feathery, or rather fan- 

 like, that it well deserves its name of plumosa." 



In almost any little pool, between tide- marks 

 or even hanging from rocks that have been left 

 quite dry, may be seen thick tufts of a coarsish 

 horsehair-like plant, of a dull green colour, 

 often dashed with black. This is the Gladophora 

 Tupestris, one of the commonest species out of 

 the twenty that are exclusively marine. There 

 are two species that inhabit ditches and lakes 

 where the sea occasionally obtains admission, 

 and several others that prefer water entirely 

 fresh. The length of the tufts is about four or 

 five inches, often less, but seldom more. 



Anxother species of the same genus, Cladophora 

 arcta, is of a brighter green than the preceding. 



