344 ENTOMOLOGICAL NEWS [Oct., '14 



opinata male suggests the query as to whether we are dealing 

 with two or one species here. A number of species of Odonata 

 are known (not to mention other groups) in which there is one 

 form of male and two forms of females within the same spe- 

 cies. Such are members of the genera Ischnura, Anomalagrion, 

 Ceratiira, Agriocnemis and Neiirothemis, Erythrodiplax um- 

 brata and funerea. While some of these so-called dimorphic 

 females are explicable as due to differences in age, others can 

 not be interpreted in that way. Can Thaiimatoneura present 

 an inverse case in which there are two forms of males and but 

 one form of female in the same species? This leads us to con- 

 sider the differences between the pellucida and inopinata males. 



When I originally described pellucida male. I could find only 

 two differences between it and inopinata male. One of these 

 was the absence of any coloring on the wing, the other the 

 presence of "a transverse pale citron band on nasus and on 

 frons connecting the yellow genal spots," this band being ab- 

 sent in inopinata male. The pale citron of dried specimens, I 

 now know, is pale blue in life. This diversity in the coloring 

 of frons and nasus holds true for the majority of the present 

 examples, but of the fourteen males of inopinata two have the 

 pale band very well marked and three others have indications 

 of some pale color on these parts. All fourteen pellucida males 

 have the pale band. The inopinata males are slightly larger, 

 average length of the abdomen 58.7, range 55-61 mm. ; hind 

 wing, average 47.6, range 45-49 mm. (14 specimens). Pel- 

 lucida: Abdomen, average 57.25, range 52-61 ; hind wing, aver- 

 age 46.85, range 44.5-49.5 mm. (14 specimens). I have not 

 been successful in finding any other differences in the imagos. 

 There is no reason to think that the two forms represent age 

 differences because no transitional individuals (so far as the 

 presence or absence of the coloring of the wings is concerned) 

 have been found. We have seen both forms emerge from the 

 larval exuviae at metamorphosis, and both forms become 

 equally pruinose on the body although so markedly different in 

 wing coloring. 



The seasonal distribution of our males is as follows: In- 



