have fulfilled a useful task in bringing together and placing 

 in an accessible form, the various names scattered through 

 numerous publications. The tendency of his investigations 

 in this department of the subject, has been to the effect, that 

 many plants of the value of mere varieties constitutional or 

 geographic, have been hitherto regarded as species ; and he is 

 prepared to believe that a more complete acquaintance with 

 the modifications of form resulting from wide distribution, 

 would lead to the combination of plants which he has here left 

 separated. Notwithstanding this, he cannot but think that at 

 the present day the current of opinion seems to be setting too 

 strongly in this direction, in the disregard which is paid to 

 actual differences a state of things which, equally with the 

 other extreme, is opposed to the possibility of defining with 

 precision, and consequently of recognising species. 



The author ventures to hope that he may solicit the further 

 aid of Botanists in the execution of his task. In particular, 

 either information or materials which may throw light on such 

 of the species of the older authors as may still remain obscure ; 

 or such as may assist in the recognition of the new unfigured 

 species of later writers, or in correctly indicating the 

 distribution of the species generally, would be serviceable to 

 him ; and he further trusts that those who may discover errors 

 will have the goodness to point them out with the view to 

 their correction. Any communications of the nature here 

 indicated, may be sent to him, under cover to the Publisher, 

 Mr. Pamplin, Frith Street, London. 



The work will be issued in Parts, as rapidly and as 

 regularly as its preparation will permit ; and will commence 

 with the Synopsis of the Genera as a basis for the Enume- 

 ration of the Species. It is hoped that it may be found 

 practicable to issue one part monthly. 



