165 



As far as 1 know the ''inomxjnipliie specialc"' was never published. 



Calvert, too. in a paper which has just appeared on the genus Argia, 

 reco.iiuizes this structure.* 



This structure occurs, as far as I have examined, in all the native 

 genera of the Zygoptera. but it is laclcing entirely in the Anisoptera or 

 possi])ly is replaced tin re l>y the low transverse carina across the extreme 

 anterior end of the mesepisternuni. It is found on the same general plan 

 in the different genei'a. consisting of a heart-shaped enlargement of the 

 mid-dorsal carina, on either side of which is a triangular wing with its 

 apex nuniing down to the mesinfraepisternum. 



.hern ,btsalcirifj 



In the genus Argia a more or less oblong depression (cavity— see figure 

 abovei. bounded on either end by the high basal carina of either wing 

 (see figure aliovei occurs in front of tlie heart-shaped end of the mid- 

 dorsal carina. The l)asal carina of each wing ends in front in a horn, 

 and l)eliind. in the case of the females of four of the five species, in an 

 ear-lil<e lobe (the ear— see figure abovei. In the male no elaliorate ex- 

 pansion into an ear occurs. The most strilving differences in this sti'ucture 

 are those of the size and shape of the ears. As these ears are absent in 

 the males, for tliem tlie structure loses most of its diagnostic value. How- 

 ever, for interest in comparison, figiu-es of this structure as it occurs in 

 the males of the five species are shown in the plate (see Plate II, Figs. 

 1. .■>. •">. 7 and 0). Ky reference to tliem it will lie seen at once that, in the 

 male, this structiu-e is of a more generalized type than in the female. The 

 structure as found in the male is nearer the general type found in related 

 genera. 



The .above would seem to indicate that this structure is a sexual organ 

 functiiining in the female and merely passively present in the male. One 

 would at (inco jump at the conclusion tliat it is tlie organ by wliicli tlie 

 male holds the feiiiah' during rhe act of cupulatinn. Tlic cavity would 



■Cidvert, Bull, Mus. Coiiip. Zool Xov. 1902. 



