1911] Muttkowski, A Synonymical Sute. 169 



left hind wing the origin of i\l2 is spurious, namely, it arises 

 from a. crossvein which forms part of an inserted triangular cell 



(Schaltzelle Ris.)* 



In the foregoing three points are evident : 



i. In American Ccenagrion there is a strong tendency toward 

 Ischnura venation, especially in the hind wing. 



2. The venation of Palearctic Ccenagrion is more normal, i. e. 

 it approximates that of Bnallagma. 



3. Hawaiian species show a tendency to increase the num- 

 ber of postnodals, and the origin of M2 is correspondingly separ- 

 ated from the nodus by a greater number of cross veins. 



These considerations offer food for thought for the phylo- 

 genist. There can be little doubt of the fact that Ischnura is more 

 specialized than Bnallagma and Ccenagrion, which latter genus is 

 more recent than its relative. In the tendency toward simplifica- 

 tion the American species of Ccenagrion appear to be more ad- 

 vanced than Palearctic species, while Hawaiian species are most 

 primitive. 



Milwaukee Public Museum, September 1, 1911. 



* An enlargement of a wing- photograph of this specimen has been 

 made and will be published later on with a detailed study of the) aberra- 

 tion, which is aberrant not only in respect to M2 but also in respect to most 

 major features of wing- venation.— March 18, 1912. 



