ADVERTISEMENT. 



The present volume comprises two separate installments of a compre- 

 hensive work designed by the author to embrace a systematic synoptical 

 review of the entire Flora of the North American Continent. Nearly 

 forty years ago such a work, undertaken by the joint labors of our 

 two eminent botanists, Professors Torrey and Gray, was arrested by 

 the pressure of other duties, with the execution of the Polypetalous 

 division of the DICOTYLEDONS, the first class of the great PH^ENOGA- 

 MOUS series, and five orders of the Gamopetalse, including the great 

 order of the Compositse. This comprises just the scope of the projected 

 first volume of the present series. 



Assuming that the reconstruction of the first division the Polypetalse 

 would occupy some 500 pages, to constitute the 1st part of Vol. I, this 

 present 2d part of the volume is made to commence with the Gamo- 

 petalse, the full exposition of which second division extends through the 

 1st part of Vol. II. The 2d part of Vol. II will probably be occupied 

 with the third division of the DICOTYLEDONS the Apetalse ; and Vol. 

 Ill is designed to take up the MONOCOTYLEDONS. 



The present publication, therefore, though made up of two consecutive 

 parts of different volumes of the work, may be said to be complete in 

 itself in giving a complete view of the entire division of the Gamopetalse. 



The preparation of the work has been largely aided by the funds of 



the Smithsonian Institution. 



S. P. LANGLEY, 



Secretary S. I. 



WASHINGTON, December, 1887. 



(iii) 



