3:10 niESH-WATER ALGiE. 



the volume without describin<? a few of the fresh-water 



o 



Algse. 



Many may wish to learn something of Algology who are 

 at a distance from the sea, and have no opportunity of col- 

 lecting sea-plants in a recent state. It is well to let such 

 know that fresh- water Algology opens up for them a wide 

 field, which of late has been very successfully cultivated by 

 British botanists. In 184^5 we were favoured by Mr. Hassall 

 with an excellent work on the History of British Fresh- 

 water Algae, in two volumes, one of letter-press and the 

 other of plates ; and in 1848 we have had another admirable 

 work by Mr. Ralfs, on British Desmidiese, in one handsome 

 volume, containing accurate descriptions and exquisite illus- 

 trations, in thirty-five plates. To these two works we refer 

 tliose who devote themselves to this study; but as many 

 may not be disposed to purchase costly works, however 

 excellent, till they know something of what they contain, — 

 without attempting to treat of fresh-water plants at all 

 systematically, we shall describe a few, as a kind of sample 

 of the rich stores within the reach of the naturalist, however 

 remote from the sea. 



One reason, no doubt, why these plants are not more 

 generally studied, is, that they are so minute that their 

 beauty cannot be seen by the unaided eye. Even in the 



