re 
COLOR AND SEX. 45 
exact value remains to be determined by closer obser- 
vation. | 
Color and Sex.*—It is not possible here to discuss at 
length the vexed question of sexual coloration. But, as a 
means of directing observation, I present a synopsis of 
the principal types of secondary sexual characters, with 
some of the theories which have been advanced to ac- 
count for them. 
SYNOPSIS OF THE SECONDARY SEXUAL CHARACTERS 
OF BIRDS. 
I, STRUCTURAL, 
Male larger than female (usual). 
Size. : Female larger than male (rare). 
4 Color. Male brighter than female. 
* ) Female brighter than male (rare). 
Assumption of plumes, ruffs, crests, eigen, 
Plumage. + etc.: special modification of wing and tai 
Form. feathers. 
a. Worn by male alone. 
q 6. Worn by both sexes. 
Sole or greater development in male of brightly col- 
Of the body. ored bare tracts of skin, combs, wattles, caruncles, 
and other fleshy or horny appendages. 
Of the feet. Sole or greater development in male of spurs, 
Male with more highly colored or larger bill than 
Of the bill. ; female. 
Il, FUNCTIONAL. 
By male when similar to or brighter than female. 
Pursuit. ; By female when brighter than male, 
Display. By male of accessory plumes and other appendages. 
Battle. By male using spurs, wings. bill, etc. 
Masic. Voeal, by male and, rarely, female. _ 
Mechanical, by male and sometimes female. 
Dances, mock fights. atrial evolutions, construction of 
Special bowers, decoration of playgrounds, attitudinizing, 
habits. strutting, etc, 
a. By male before the female. 
6. Among the males alone. 
* Read Darwin, The Descent of Man and Selection in Relation to 
Sex (D. Appleton & Co.). Wallace, Darwinism (Macmillan Co.). 
