Boreali-Americana" as near as possible, avoiding 

 carefully to change old established names, however 

 faulty, unless in cases where good authority furnished a 

 more appropriate one. As for example, I have adopted 

 JFraxinus acuminata of Lamarck, instead of Fraxinus 

 americana^ Linn., and Cynoglossum amplexicaule of 

 Michaux for Cynoglossum virginicum, Linn. But I 

 have never approved of such changes as Juglans alba 

 and cinerea of Linnaeus to Juglans squamata and ca- 

 thartica, as the younger Michaux in his '^ Arbres Fores- 

 tiers" has done. This otherwise very useful publication 

 is full of such new names, imposed on well known and 

 long established species, and sometimes even without 

 the least hint respecting their names in other authors. 



The specific characters in most instances have been mo- 

 delled anew or altered as it was found necessary. Where- 

 ever any alteration had been made it was necessary to 

 quote the author from which the species had been taken 

 in a separate line, as page IC Monarda didyma ; after 

 the specific description I had to repeat that it was the 

 same with M. didyma, Willd. sp. pi. l.p. 125. To 

 avoid this superfluous repetition, and save as much room 

 as possible, I found it expedient to adopt, from page 72 

 to the end, the following mark ( — ), to be placed after 

 the specific character whenever it had been amended : 

 so that Stipa avenacea, page 72, is the same species de- 

 scribed by Willd. sp. pi. 1. p. 442, but the character is 

 new or augmented. Wherever the author follows the 

 description without this mark, as page 73, Saccliarum 

 giganteum^ Pers. ench. 1. p. 103, in that case the cha- 

 racter has been adopted without alteration. 

 b2 



