82 



THE GENERAL FEATURES OF WINGS 



The epiplenros. — A part of the outer margin of the elytra of beetles 

 when turned down on the side of the thorax is termed the epipleura. 



Fig. 70. — Wings of Myrmecia; b, b, b, bullae. 



Fig. 7 1 . — Wings of Labidarge dibapha ; 

 ap, appendiculate cell. 



The transverse cord. — In many cases the wing is strengthened by a 

 transverse series of cross-veins or of cross-veins and divaricated forks of 

 longitudinal veins extending across the wing just beyond the middle of its 



length. This series may be designated 

 as the transverse cord. In the wings 

 of Hepialus (Fig. 72), there is a trans- 

 verse cord extending between the 

 points marked a and b in the figure. 

 In this case the transverse cord does 

 not extend to either margin of the 

 wing; but in many insects it reaches 

 one or both margins. 



The discal cell and the discal vein. — 

 There are two terms that, although 

 not belonging to the uniform terminology, are frequently used as a matter 

 of convenience by those who have adopted the uniform terminology; these 

 are the discal cell and the dis- 

 cal vein. Si 



These terms can not be ^- 



made a part of the uniform 

 terminology for they are not 

 used in a uniform manner, 

 being applied to different 

 parts of the wing by the 

 writers on different orders. 



The term discal cell is 

 applied to a large cell which 

 is situated near the center of the wing; and the term discal vein, to the 

 vein or series of veins that limits the outer end of the discal cell. 



Fig. 



2d A 



72. — Wing of Hepialus; a-b, the transverse 

 cord. 



