1893.] Evolution in the Genus Megascops. 521 
EVOLUTION AND DICHROMATISM IN THE GENUS 
MEGASCOPS. 
By E. M. HASBROUCK. 
INTRODUCTION. 
The subject of Dichromatism has ever been a stumbling- 
block to scientific research, and from the time of its earliest 
admittance into zoological discussion, has been without 
apparent cause and without explanation. Few, if any, theo- 
ries have been published as to what it really is, or as to the 
possible influence governing it, while any theories that have 
been advanced stand without proof of their correctness; a 
new theory, therefore, cannot be considered as conflicting with 
any settled doctrine upon the subject. When we find a peculi- 
arity common to all forms of animal life, it becomes apparent 
that if thoroughly understood in one form, a flood of light 
will be thrown upon the same perplexing problem affecting 
the rest of the animal kingdom. 
In attempting to explain the causes and effects of dichrom- 
atism in the Screech Owl, no stone has been left unturned to 
prove the correctness of the views herein set forth. The writer 
has labored lovingly and patiently, following a course of rea- 
soning which he believes to be correct, and in submitting his 
work and its results to fellow-workers would ask for it their 
kindly consideration. The collection of the necessary data 
has been an extremely difficult task, and more information is 
still desirable from certain localities, although sufficient has 
been received to make possible the construction of a compara- 
tively accurate map of the color distribution. It is a lament- 
able fact that scientific observers of bird life are exceedingly 
scarce in the southern states and in the lower part of the Mis- 
sissippi Valley. The data obtained from these regions, 
although to a certain extent more scanty than could be 
desired, has been used. to the best possible advantage. In 
obtaining information, copies of the following circular letter 
