PHILIP A. MUNZ 3 



I— INTRODUCTION 



At the present time it is not necessary to offer either explanation 

 or excuse for the use of venation as a guide to the phylogeny of a 

 group of insects, particularly of any of the Neuropteroids, the 

 exceedingly rich and varied veining of which has been the basis of 

 many excellent pieces of work. The purpose of this paper is to 

 make the fullest possible use of wing-veins as a means of interpre- 

 ting relationships and as a method of identifying the genera of one 

 of the suborders of the Odonata, the Zygoptera. It must be remem- 

 bered, however, that venation is not the only index to genealogy, 

 nor perhaps always the most reliable, but it is one of the most 

 evident and fundamental and therefore most valuable methods 

 which we have to enable us to determine relationships. In some 

 cases, without doubt, a study of genitalia and morphology will throw 

 more light on the situation and even change some of our concep- 

 tions which have been arrived at from the study of the wings only. 



The nomenclature of the veins of the Zygoptera and their 

 homologies to those of other groups have been thoroughly worked 

 out, but, since the days of Baron de Selys, no attempt has been 

 made to consider the whole suborder in detail and to make keys 

 for identification. A word of explanation may be permissible in 

 regard to the keys herewith submitted; I have examined such 

 material as I have had access to in an endeavor to make them as 

 generally applicable as possible; but in some cases descriptions , 

 only could be used, since during the past two years correspondences 

 with many European workers and hence the securing of many\ 

 desirable figures ha\'e Ijeen imj^ossible. I feel, however, that the 

 paper is justifiable, if for no other reason than to ha\'e in one place 

 in the literature such wing-photographs as have been collected in 

 the course of the work, the \'enation of many genera not ha\-ing 

 been published before. 



A cknowledgemeuts 



To the many who have kindly contributed material and sugges- 

 tions for this study my gratitude is due and is thankfully given. 

 This problem was undertaken at the suggestion and under the 

 direction of Professor James G. Needham, whose unfailing interest 



MEM. AM. ENT. SOC, 3. 



