126 University of California PuUications. [Entomology 



but they are so small as compared with the width of the wing 

 that they are a very unimportant addition to the effective 

 width. 



The front wing is generally distinctly wider than the hind 

 wing, and when this is the case, the venation of the latter is 



very much simpler. The general 



_ -^ character of the venation is shown 



''^ ^' -'• ^,-, - j_^ in Fig. 66. No one has before 



attempted to homologize the veins, 

 FIG. 66 Diagram of the vena- bccause the venation was so simple 



tion of the Physopoda. Dotted -t^ 



lines indicate veins that may be ^1^^,^ it COUld not be made to fit 

 absent. 



into the complex schemes of vena- 

 tion of previous investigators. According to the scheme here 

 proposed, there is no difficulty in the matter. We see the 

 marginal, the primary, a posterior, and an independent. The 

 latter, with the cross veins being often wanting. 



COLEOPTERA. 



The front wings in Coleoptera are so completely transformed 

 into protective coverings for the hind pair, that their venation 

 is almost indistinguishable. The hind wings possess veins 

 of two types, usually quite distinct. Those near the base are 

 cylindrical, and resemble the veins of more typical wings, 

 while those toward the tip are usually solid for the most part, 

 and tend to fade out around their edges so as to become very 

 indefinite in shape. These are usually not treated as veins, 

 but we have previously shown that they are not essentially dif- 

 ferent from undoubted veins. In this case they are certainly 

 not to be homologized with any veins in other orders, in spite 

 of their essentially identical structure. 



The most characteristic thing about the hind wing in this 

 order is the manner of folding. These wings exhibit a good 

 deal of variation in this respect, but there is one point in which 

 they all agree, if the wing folds transversely at all — abortive 

 wings, or those not fully covered by the elytra, lose the charac- 

 teristic fold that occurs in all normal wings. This common 

 character is the dividing of the area between the two strong 

 divergent veins — the primary and the first posterior — into four 

 triangular areas by the lines of folding. These triangles may 

 be seen in Figs. 67-70. Besides these, there is always one, and 

 sometimes two, basal folds, and there are also extremely 



