408 
THE STUD V OF INSECTS. 
slightly with brown to a dark cinnamon color; they are 
bordered with black, and all the veins are edged with the 
same color (Fig. 479). The fringe of the wings is spotted 
with white, and the black border on the outer margin con¬ 
tains a row of white spots. 
Fig. 479 —Basilarchta archif>f>us % 
This species is remarkable for its resemblance to the 
Monarch (Anosia plexippus , Fig. 469). But aside from the 
structural characters separating the two subfamilies which 
these butterflies represent, the Viceroy can be easily distin¬ 
guished from the species it mimics by its smaller size, and 
by the presence of a transverse black band on the hind 
wings. 
It is believed that the resemblance of these two species 
is not merely accidental, but is a result of the action of the 
law of natural selection. The butterflies of the subfamily 
to which the Monarch belongs ( Euplceince ) are exempt from 
the attacks of birds. It is supposed that this exemption is 
due to the possession by these butterflies of a disagreeable 
odor. With such an odor the conspicuous coloring of the 
butterflies is protective, the birds soon learning that such 
butterflies are not fit for food. And it can be seen that these 
birds will naturally leave undisturbed any other butterflies 
