128 



University of California Pxiblications. [Entomology 



FIG. 68. Diagram of the venation and folding 

 of a beetle with double basal fold. Dotted lines 



forward, as contrasted with the wing previously studied. An- 

 other type of folding, as seen in Dermestes and other beetles 

 with rather short wings, is shown in Fig. 69. This can be 



compared, area for area, 

 with the wing last con- 

 sidered, but the result is 

 a single rather than a 

 double folding of the 

 apical region. These 

 three types of folding 

 may be considered as 

 representing three stages 

 in the development of 

 a complicated folding, 

 such as is found in the 



are lines of folding; black areas those reversed lonff-winffcd formS the 

 in folding. ° 8 > 



fundamental, or short- 

 winged, type being represented by Dermestes, and the culmi- 

 nating stage being seen in Staphylinus. 



The Staphylinid type is illustrated in Fig. 70. Here there 

 are three transverse folds and several added longitudinal folds 

 in the apical region of the wing. The method of inserting a 

 longitudinal fold is clearly 

 indicated in the diagram. 

 The carrying of the basal 

 transverse fold across the 

 anal region is another fea- 

 ture in which this insect is 

 peculiar. 



The venation of beetles, 

 as will be seen in these 

 illustrations, consists of two 

 distinct types, as was first 

 pointed out by the author 

 (Wood worth, '89). One is 



seen in Fig. 67, the other in Figs. 68-70. In the former, there 

 is a cross vein beyond the first transverse, and the whole 

 venation about the fold is unique. 



The most conspicuous elements of a beetle's venation are 

 the primary and the first posterior; between them there are 

 two independents. Basal to the fold, one or both of these may 



FIG. 69. Diagram of venation and folding 

 in Dermestes lardarius. Dotted lines indicate 

 folds; black areas those reversed in folding. 



