1922] Graham: Wing Venation of Coleoptera 197 



calosities in the apical area which often resemble veins so 

 closely that it is only by the study of a series of wings that 

 their origin becomes clear. The presence of these secondary 

 vein-like calosities has undoubtedly led to much confusion in 

 studies of the wing venation of this order. In the plates these 

 structures are indicated by stippling, while the true veins are 

 represented by solid lines. 



The pushing toward the base of the primary venation, as 

 mentioned above, is apparent in the most primitive types of 

 Coleopterous wings studied, but is much more striking with 

 increased complexity of folding. The extreme of this modifica- 

 tion is found in the Staphyhnidae, but a highly specialized 

 condition is also apparent in other widely separated families 

 such as the Scarabaeidae, Silphidae, Nitidulidas, Ipidse, and 

 Curculionidas. Thus it appears that this line of modification 

 is correlated with the complexity of folding. Increased com- 

 plexity of folding is made necessary in two ways. Either by 

 a shortening of the elytra as in the Staphylinidae or by shortening 

 and thickening of the body, thus decreasing the elytral length 

 as compared with the wing length as in the Scarabaeidae. 



Along with this migration of the primary venation toward 

 the base of the wing and due also to increased complexity of 

 folding, there occurs a reduction of veins. Also many veins 

 become broken and branches become entirely separated from 

 the veins of their origin. 



PHYLOGENETIC SIGNIFICANCE. 



It is apparent that the final determination of phylogenetic 

 relationship cannot be based upon wing venation alone any more 

 than it is possible to base such relationship upon tarsal, thoracic, 

 or any other set of characters alone. The wings do, however, 

 give some hints which will undoubtedly be of considerable 

 value when correlated with other characters. 



The first point which is brought out in this study is that the 

 Lampyridae, using that term in its broad sense, are characterized 

 by a much simpler type of venation than any other group of 

 the order. The venation of this family approaches very closely 

 what was probably the primitive type. This, coupled with 

 the fact that the Lampyridae exhibit other primitive characters, 

 such as soft wing-like elytra, soft integument, a larger number 



