ADVEETISEMENT TO THE THIKD EDITION. 



In preparing this edition, I have taken every pains 

 to make it a complete elementary guide to the 

 study of our marine Algse. I believe, from the 

 growing interest which is now manifested in the 

 investigation of these beautiful plants, that the ad- 

 ditional information suppUed both in the Introduc- 

 tion and in the descriptive portion of the work, 

 will meet with general approval. Besides the de- 

 scriptions of the common sea-weeds, concise notices 

 of the distinguishing features of the rarer ones 

 are now included, thus furnishing the student with 

 the characters of all the kinds found on our shores, 

 classified and named in accordance with the ar- 

 rangement and nomenclature adopted by Dr. Har- 

 vey in the last edition of his excellent work, the 



