THE PHYLOGENY OF THE ZYGOPTEROUS DRAGON- 

 FLIES AS BASED ON THE EVIDENCE 

 OF THE PENES* 



Clarence Hamilton Kennedy, 

 Ohio vState University. 



This paper is merely the briefest outHne of the writer's 

 •discoveries with regard to the inter-relationship of the major 

 groups of the Zygoptera, a full account of which will appear in 

 his thesis on the subject. Three papers^ by the writer discussing 

 the value of this organ in classification of the Odonata have 

 already been published. 



At the beginning, this study of the Zygoptera was viewed as 

 an undertaking to define the various genera more exactly. The 

 writer in no wise questioned the validity of the Selysian concep- 

 tion that placed the Zygopterous subfamilies in series with the 

 richly veined " Calopterygines" as primitive and the Pro- 

 toneurinae as the latest and final reduction of venation. 



However, following Munz- for the Agrioninse the writer was 

 able to pick out here and there series of genera where the devel- 

 opment was undoubtedly from a thinly veined wing to one 

 richly veined, i. e., Megalagrion of Hawaii, the Argia series, 

 Leptagnon, etc. These discoveries broke down the prejudice in 

 the writer's mind for the irreversibility of evolution in the 

 reduction of venation in the Odonata orders as a whole. Undoubt- 

 ably in the Zygoptera many instances occur where a richly 

 veined wing is merely the response to the necessity of greater 

 wing area to support a larger body. 



As the study progressed the writer found almost invariably 

 that generalized or connecting forms were usually sparsely 

 veined as compared to their relatives. The first startling dis- 

 covery was that Hy poles tes (Ortholestes) was a near relative of 

 Amphipteryx and not Lestid at all, others followed; Hemiphlihia 

 had no near relatives in the Coenagrioninse but was probably 

 nearer the Megapodagrioninae, that the minute Micromerus was 

 the least specialized Libellagine genus that the Megapodagri- 



*A second paper will appear in the Ohio Jour, of Sci. for December. 



1 Ent. News, July, 1916, Jan., 1917. July, 1917. 



2 Mem. Amer. Ent. Soc. No. 3, 1919. 



19 



