132 ORGANIC EVOLUTION 



forms, Pierid&\ found so frequently about wet places in the 

 roads (Plate 59, A\ and most of the swallow-tailed butterflies, 

 Papilionidce, which are our most conspicuous North American 

 forms (Plate 76, D\ Some moths show warning color (Plate 

 70, A-K\ The larvae of many moths and butterflies are 

 inedible, and these also are conspicuously colored (Plate 71). 



Wallace, in his Darwinism, says : " These uneatable 

 insects are probably more numerous than is supposed, 

 although we already know immense numbers that are so 

 protected. The most remarkable are the three families of 

 butterflies Heliconidce [Plate 77, A-D~\, Danaidcz [Plate 

 76, A, E, and Plate 84, E and F~\, and Acrczidcz [Plate 76, 

 G, /, and 77, /, Z] comprising more than a thousand spe- 

 cies, and characteristic respectively of the three great tropical 

 regions: South America, Southern Asia, and Africa. All 

 these butterflies have peculiarities which serve to distinguish 

 them from every other group in their respective regions. 

 They all have ample but rather weak wings, and fly slowly. 

 They are always very abundant ; and they all have con- 

 spicuous colors or markings, so distinct from those of other 

 families that, in conjunction with their peculiar outline and 

 mode of flight, they can usually be recognized at a glance. 

 Other distinctive features are, that their colors are always 

 nearly the same on the under surface of their wings as on the 

 upper ; they never try to conceal themselves, but rest on the 

 upper surfaces of leaves or flowers ; and, lastly, they all have 

 juices which exhale a powerful scent, so that when one kills 

 them by pinching the body, the liquid that exudes stains the 

 fingers yellow, and leaves an odor that can only be removed 

 by repeated washings. 



" Now there is much direct evidence to show that this 



