THE WORTH KNOWING SERIES 
Four Volumes, Containing Nearly 200 Illustrations, 144 of Which Are in Color 
Fully Indexed 
Birds Worth Knowing 
By Neltje Blanchan 
Trees Worth Knowing 
By Julia Ellen Rogers 
Butterflies Worth Knowing 
By Clarence M. Weed 
Flowers Worth Knowing 
Adapted from the works of Neltje Blanchan 
By Asa Don Dickinson 
T HE Worth Knowing Series forms a much needed in-between link to the 
larger Nature Library books and the handy, but necessarily limited, 
Pocket Nature Guides. 
Each of these four volumes covers the most interesting American varieties 
of the subject treated. 
A general introduction to each subject is followed by detailed descriptions 
of the most interesting families, and of the more important members in each 
group. 
EACH VOLUME, NET, $1.60 
