Vol. 1.] 



Woodirortli . — ^y i lui V-'/^.s of Insects. 



127 



variable apical folds. In Fig. 67 the veins show very distinctly 

 the lines of folding for a double basal fold, but in this case the 

 wing is folded only once. The breaks in the veins in this case 

 are doubtless vestigial. 



The method of folding is as follows: The largest Avhite area, 

 the third coming from the front margin near the base, is the 

 only one that remains uncovered. All the adjacent areas 

 bend under it. The area in which the primary vein lies is 

 thus brought partly beneath this area. The two small triangles 



FIG. 67. Venation and folding of Harpalus caliginosis. Dotted 

 lines indicate lines of folding; black areas those that are reversed 

 in folding. 



also fold so as to lie partly over the primary vein. The tip of 

 the wing beyond the triangles folds first longitudinally along 

 a slight curve, which causes the extreme tip to fold back upon 

 the more basal portion. The folding is brought about by the 

 approximation of the tips of the primary and the first posterior 

 by their own elasticity, and the extension of the wing by a pull 

 on the anterior marginal by the extensor muscle. 



In the form represented in Fig. 68 the same method of folding 

 occurs for all but the anal area, where there is one more com- 

 plete fold. In this wing, as in the one previously considered, 

 the area (white) containing the first posterior vein is upper- 

 most when the wing is folded, all the adjacent areas being 

 doubled beneath it. The most striking feature of this wing is 

 the arrangement of the veins wherebv this third area is carried 



