PREFACE 



SINCE the last introduction to the study of sea- 

 weeds was written, many years ago, the aspect of the 

 whole subject has been completely changed by 

 the progress of research. I have attempted in the 

 following pages to keep the rule of describing only 

 what I have personally verified by examination or 

 by inspection of the original account, and this has 

 been possible in nearly every case. 



It would have been more in accordance with 

 usage to begin with the sub-class Rhodopliycecc, but 

 I have permitted considerations of convenience to 

 prevail. The Rhodophyccce present so many diffi- 

 culties, to be understood only after the study of 

 other groups, that I have chosen Phwophyccm, with 

 its familiar forms of sea- wracks and tangles, for the 

 first sub-class. The Chlorophycem and Diatomacccc 

 follow naturally. The Rhodophycem next make a 



