258 ENTOMOLOGICAL NEWS fJ une > ?I 3 



The Medio-anal Link in Agrioninae (Odonata). 



By E. B. WILLIAMSON, Bluffton, Indiana. 



Venational characters may generally be described in a vari- 

 ety of ways ; and the number of ways depends largely on the 

 complexity of relationships of the part or character defined 

 or described. I do not refer to the use of synonyms (as tri- 

 angle free, triangle uncrossed), but to those characters which 

 for their definition depend on some expressed or implied rela- 

 tionships with other characters or parts. It may be taken for 

 granted that, in describing any part of the wing, that descrip- 

 tion is best which is clearest, and which places most import- 

 ance on evolutionary changes of that or related parts. More- 

 over, it is desirable that all workers should be in harmony in 

 their use of terms and their conception of evolutionary 

 changes. When such harmony exists, uniformity of descrip- 

 tions will inevitably follow. 



The Agrioninae alone remain about as the genius of de 

 Selys, expressed in his classification, left them. His Legion 

 Lestes has properly been given subfamily rank, but on no 

 characters not recognized by him. It is certain that the con- 

 tents of others of his legions and "grandes genres" will be 

 altered more or less, and also that many of his groupings or 

 divisions under his subgenera will be described as genera. 

 Probably thus more Agrionine genera will be described in the 

 future than all other Odonate genera yet uncharacterized. 

 Moreover, the literature may be expected to be voluminous, 

 and for this reason uniformity in descriptions is desirable and 

 possible. 



For venational descriptions the Comstock-Needham system 

 seems most desirable ; and Needham in his Genealogic Study 

 called attention to the evolutionary changes which have taken 

 place in the veins forming the distal (apical) ends of the 

 quadrangle and subquadrangle. Later I named these two 

 parts in the Calopterygidae the medio-anal link. The medio- 

 anal link may now be defined as the cross vein forming the 

 distal end of the quadrangle and that part of Cu2 opposed 

 to Cui and placed transversely to the long axis of the wing. 



