PREFACE 
TO THE THIRD EDITION. 
Eexcounacen by the public reception of the for- 
mer editions, the Author has spared neither labour 
nor expence, to render this as perfect as his op- 
portunities and abilities would permit. The pro- 
gress of botanic knowledge is so rapid, and the 
discoveries so numerous, both at home and abroad, 
that this. may rather be regarded as a new work | 
than as a republication of an old one. On this 
account, a short enumeration of the more important 
changes may possibly be expected by the reader. 
The Genera are now taken from Scureger’s 
Genera Pianrarum, published at Frankfort in 
1789, and 1791. The structure of each Genus is 
~ illustrated by references to such figures as are best 
calculated to give an idea of it, particularly those 
‘in the Jnstitutions of Tournerort, the works of : 
_Garrner, and the Cryptogamia of Hepwic. The 
" exceptions and observations at the end of cach 
Genus are also. a augmented. : 
The characters of the species have been com- 
pared with the third edition of the Species Plan- 
tarum,andwith GMeuin’s Systema Nature published 
