Vlll PREFACE. 



an introduction to the study, and a guide to his early 

 Avanderings on the shore among the rocks and tide-pools. 

 I have freely used all the works mentioned above, par- 

 ticularly the ' Nereis Boreali- Americana ' and ' Phyco- 

 logia Britannica/ and have endeavoured to condense the 

 facts that they contain into the most intelligible, least 

 technical, and briefest language that a strict regard for 

 scientific accuracy would permit. I have, also, recorded 

 with diffidence the results of my own experience and 

 study, and have collected all the information that I 

 could obtain from friends and fellow-students. 



I have embodied in the text my acknowledgments to 

 those persons who have kindly furnished me with speci- 

 mens or information ; I must here thank those from 

 whom I have received more general assistance. I am 

 most deeply indebted to my uncle, Dr. John Edward 

 Gray. His early instruction and great example first led 

 me to take delight in the study of botany ; his recom- 

 mendation obtained for me this opportunity to use the 

 knowledge that he had induced me to acquire ; his library 

 has supplied me with the costly scientific works to which 

 I have had to refer ; and the material in his ' Handbook 

 of Water-weeds ' and his manuscript notes have been 

 freely placed at my disposal. For all these benefits, and 

 for his valuable counsel, which has been, during the pre- 

 paration of these pages, as it has been throughout my 

 life, my ever-ready resource on any occasion of doubt or 

 diflaculty, I am deeply grateful. To Mrs. Gray, also, I 

 owe many thanks, for the advantages that I have de- 

 rived from the study of the authentic specimens of rare 



