156 BUTTERFLIES 



have two distinct forms of coloring. The winter form has 

 been given the variety name harrisi. The butterflies of 

 this brood are decidedly lighter in color than those of the 

 summer brood to which the variety name dryas has been 

 given. The latter was originally described as a distinct 

 species by W. H. Edwards. 



The Change to the Chrysalis 



The manner in which a larva changes to a chrysalis is 

 second in interest only to that in which a chrysalis changes 

 to a butterfly. There are not a great many careful 

 descriptions by competent observers of this process in 

 print. One of the best of these is that by W. H. Edwards 

 in his splendid work on "The Butterflies of North Amer^ 

 ica," in which he describes the transformation of the 

 Comma caterpillar. It is as follows : 



"When about to transform, the caterpillar selects a con- 

 venient place on the under side of a projecting rock, or of a 

 fence rail, or of a weather board of the house, or the mid- 

 rib of a hop leaf, and having spun a little button of pale red 

 silk fixes the hooks of its hind legs therein and hangs sus- 

 pended, head downward, in the shape of a fishhook and 

 remains immovable for the space of twenty-four hours, no 

 change being perceptible except in the color of the skin, 

 which becomes partly transparent and loses its dark color 

 owing to its gradual parting from the chrysalis within. 

 Suddenly, and to a looker-on without any premonitory 

 symptom, a rent takes place in the skin at the back of the 

 head, just wide enough to allow the passage of the chrys- 

 alis, the head of which at once emerges. By a rapid con- 

 traction and expansion of the folds of the abdomen the 

 larva draws the skin upward, successively discovering the 



