220 PROCEEDINGS OF THE ACADEMY OF [May, 



THE ANTENODAL RETICULATION OF THE WINGS OF AGKIONINE 

 DR&GONFLIES. 



BY HERBERT CAMPION. 



When describing the remarkable fossil dragonfly Phenacolestes 

 inirandus, from Florissant, Prof. T. D. A. Cockerell laid stress upon 

 its possession of five antenodal nervures, and, upon the strength of 

 that character alone, proposed to erect Phenacolestes — together with 

 Dysagrion, also from the North American Tertiaries — into a new 

 subfamily of Agrionidae, the Dysagrioninse.^ "Dysagrion Scudder, 

 the type of the subfamily," he wrote, ''has not been supposed to 

 possess an unusual number of antenodals, but it is evidently allied to 

 Phenacolestes, which has five; and Scudder's figure of Dysagrion 

 fredericii shows two antenodals beyond the arculus, and as the first 

 two of all Agrionids must certainly have been present, there were at 

 least four." In the description of Phenacolestes mirandus it is stated: 

 "Antenodal sectors five, of which only the first two continue to the 

 radius, these being the two present in Agrioninse. The second, 

 however, does not meet, or nearly meet, the arculus, but ends on the 

 radius 204/^ beyond it (a character also of Melanagrion)." On the 

 same occasion Prof. Cockerell described the apical half of a wing, 

 also from the Tertiary of Florissant, as Phenacolestes parellelus, but 

 expressed a doubt as to the true generic position of the fossil. Sub- 

 sequently, he recorded the base of a wing having six antenodal 

 cross-nervures, which he referred provisionally to the same species.^ 



In the typical Agrionine wing we find two antenodals only, which 

 cross transversely both the costal and subcostal spaces; one of them 

 is placed before and the other at the level of the arculus. In fact, 

 so general is this 'number of antenodals in the Agrioninse, that for 

 many years it was one of the chief characters used in separating that 

 subfamily from the Calopteryginse, in which the antenodals are more 

 numerous. In a few recent Agrionines, however, three, or even five, 

 antenodals occur with more or less constancy, and we are therefore 

 no longer able to regard antenodal reticulation as a character of 



'■Bull. Amer. Mus. Nat. Hist., XXIV, p. 60 (1908). 

 ^Amer. Journ. Sci., XXVI, p. 75 (1908). 



