THE EXTERNAL ANATOMY OF INSECTS 



67 



wing of Pamphilius, where veins M4, Cu,, and Cu^ coalesce with the 

 first anal vein, the united tips of these veins is designated as vein ist A, 

 the first anal vein being its most obvious element (Fig. 80), although 

 it is really vein M4+Cui+Cu2 + ist A. 



Serial veins. — In the wings of some insects, where the wing-vena- 

 tion has been greatly modified, as in certain Hymenoptera, there exist 

 what appears to be simple veins that in reality are compound veins 

 composed of sections of two or more veins joined end to end with no 

 indication of the point of union. Compound veins formed in this 



Fig. 80. — Wings of Pamphilius. 



manner are termed serial veins. Examples of wings in which there are 

 serial veins are figured in the chapter treating of the Hymenoptera. 



In designating serial veins either the sign & or a dash is used 

 between the terms indicating the elements of the vein, instead of the 

 sign -f as the latter is used in designating compound veins formed by 

 the coalescence of veins side by side. If the serial vein consists of 

 only two elements the sign & is used; thus the serial vein in the wings 

 of braconids, which consists of the medial cross-vein and vein M„ is 

 designated as m & M2. 



In those cases where sections of several veins enter into the com- 

 position of a serial vein, the serial vein is designated by the abbrevia- 

 tion of the name of the basal element connected by a dash with the 



