vi Preface, 



received from so many sources that I must leave 

 the reference at the head of each locality to speak 

 for itself, only acknowledging the special aid that 

 has been given by Mr. James Bennie, in collecting 

 the plants of the ancient silted-up lakes of the 

 Scottish Lowlands. For the constant encourage- 

 ment of Sir Archibald Geikie, Director-General of 

 the Geological Survey, I am also very grateful. 



