%\lt Ciiiailiaii JCiitomolojbl 



Vol. XLV. LONDON. SEPTEMBER, 1913 No. 9 



MUTUAL ADAPTATION OF THE SEXES IN ARGIA 



MOESTA PUTRID A. 



BY E. M. WALKER, TORONTO. 



On August 1st, 1912, I captured a pair of Argia moesta piitrida 

 at Go Home Bay, Out., and by killing them suddenly with 

 gasoline, prevented the separation of the abdominal appendages of 

 the male from the parts of the female with which they were in con- 

 tact. I noted carefully the relations of the structures forming the 

 connection, but unfortunately made no drawings at the time, as the 

 specimens remained in their natural position after drying and the 

 connection was apparently permanent. In carrying the specimens 

 to Toronto, however, they separated, so that I have had to rely 

 upon my original observations and a close scrutiny of the struc- 

 tures concerned in my further study of the method by which 

 coupling in this species is effected. Some difificulties as to the pre- 

 cise position of the inferior appendages of the male in relation to 

 the pronotum of the female were readily solved by making plasti- 

 cine models of the parts of both sexes and fitting them together. 



The only published account of the process of coupling in the 

 genus Argia is given by E. B. Williamson in an article entitled 

 "Copulation in Odonata."* In this paper a classification of the 

 methods of coupling in a number of zygopterous genera is given, 

 and the following extract gives all that is known in regard to this 

 process in the genus Argia, the observations having been made 

 upontwo species — A. moesta putrida and A. apicalis. 



"BB. Inferior appendages forming two jaws which grasp the 

 anterior surface of the hind lobe of the pronotum of the 

 female, the superior appendages resting in cups formed by 

 depressions in the mesostigmal laminae and the rear surface 

 of the hind lobe of the pronotum and, depending on their 



*Ent. News, XIII., pp. 143-148, 1906. "~ 



