ADVERTISEMENT TO THE SECOND EDITION. 



EIGHT years have now elapsed since the publication of the 

 first edition of this work, and during this period much has 

 been done, both in this country and on the Continent of 

 Europe, to further our acquaintance with the Algae. Many 

 new species have been discovered, the natural result of a 

 greater attention to the subject ; and much has been done 

 to advance our knowledge of the structure and fructifica- 

 tion of these plants. From both circumstances have re- 

 sulted many improvements in classification ; and if we 

 admit that much still remains to be done before our classi- 

 fication can be considered perfect, we may also congratu- 

 late the numerous company of British Algologists on the 

 progress that has been made in illustrating their favourite 

 branch of study, and on the flourishing condition to which 

 it has arrived. 



In the present edition an improved distribution of the 

 marine species, particularly of the Red sea-weeds (Rhodo- 

 spermeae) has been, it is hoped, introduced. I have been 

 forced, however, to omit the fresh-water Algae, which were 

 included in the first edition, for two reasons : first, because 

 they have recently been treated at large in a separate work, 

 by a cotemporary; and secondly, because my attention 

 has been so exclusively turned to the marine Algae, whilst 



