INTRODUCTION. 41 



arrangement of Engler and PrantPs " Natiirlichen Pflan- 

 zenf amilien, " adopted as a standard at the Madison Meet- 

 ing of the Botanical Section of the A. A. A. S. , seems to us 

 not sufficiently well known, accessible, and understood in 

 this country to make it advisable to adopt it at present in 

 a local Flora, or in a mere list of plants. It has been 

 adopted in Algae alone in this Catalogue. As our decision 

 in regard to the standard of nomenclature obliged us to 

 follow Gray's Manual, it seemed well to us to follow its 

 arrangement also, so far as its scope allowed, and beyond 

 that to follow the manuals and other works already 

 mentioned in the Preface. 



