VIU PREFACE 



Part II, containing the description of the groujjs of j^lants, 

 comprising about 125 pages, is delayed, but is expected to be 

 ready within a year. It will be issued separately for a time, 

 but the two parts will also be bound in one volume. 



W. F. GANONG. 

 JnsE 20, 1916. 



