THE CANADIAN ENTOMOLOGIST. 179 



is seen in other species of dragonflies and is apparently dependent 

 upon climatic conditions.* There are no other differences worthy 

 of note, except possibly the somewhat shorter interruption of the 

 antehumeral thoracic bands, the posterior spots being more elongate 

 and less rounded. 



Selys placed A. interrogatum doubtfully as a race of the palai- 

 arctic A. concinniim, with the following statement concerning its 

 differential characters (1. c, p. 1254). 



" 1° Les taches postoculaires un peu dentelees en arriere; 



"2^^ Les raies antehumerales interrompues en point d'exclama- 

 tion. 



"3'^ La tache basale carree du 2e segment non prolongee 

 jusqu'au bout, et la bande dorsale des 23 et 3e amincie en avant." 



I ha\'e not seen concinniim, but from a comparison of my 

 specimens of interrogatum with Selys' description, I think it im- 

 probable that the two forms are conspecific though evidently 

 closely related. In concinniim the antehumeral bands are entire, 

 but narrowed above, while in interrogatum they are sharply di- 

 vided, but not narrowed. In the male of concinniim the transverse 

 band on segment 2 is described as being connected by a stalk 

 with the apical ring, while in interrogatum this connection is not 

 present. Segments 3-5 are described as being black in the apical 

 half, whereas in interrogatum the black area includes considerably 

 less than half of segment 3, and more than two-thirds of segment 5. 

 The apical blue area of segment 7 in interrogatum is not mentioned 

 in the description of concinniim and instead of a black dot on the 

 sides of segments 8 and 9 a black line is described as present. 

 The description of the female does not reveal any differences not 

 noted by Selys. 



Hagen compares interrogatum with his so-called variety 

 servum of C. resoliitum. This is a form in which the antehumeral 

 bands are divided, resembling an exclamation mark. It is the 

 normal form in Newfoundland, but is hardh' worthy of a varietal 



*I have discussed this subject as it relates to the genus Aeshna in " The 

 North American Dragonflies of the genus Aeshna " (Univ. Toronto Studies, 

 Biol. Series, No. 11, pp. 25-29, 1912). 



