NEUEOPTERA— ODONATA-AGRIONINA. 137 



beyond more or less irregular, increasingly so towards its apex, where it 

 bends upward so as more gradually to approach the border, and finally ends 

 close to the superior sector of the triangle in a cross vein ; many of the 

 cellules in the apical half of the postcostal space are broken by cross veins 

 forming a broken supplementary sector here, and the same thing occurs 

 feebly in the interspace above. Pterostigma scarcely more infumated than 

 the disk of the wing, expanding slightly in the middle, about four times as 

 long as broad, surmounting five to six cellules. Quadrilateral very slender, 

 five or six times as long as its basal breadth, its lower about one-fourth 

 longer than its upper side, its outer side oblique. Nodus rather more than 

 one-thu-d way from tlie base to the pterostigma ; twenty-seven postcubitals. 

 Wings rather stouter than in L. hyalinum. 



Length of wing, 34.5"" ; breadth in middle, 8.5""" ; in middle of petiole, 

 1.5"""; distance from nodus to pterostigma, 18""; from nodus to base, 

 10.5"". 



Florissant. Two specimens, Nos. 6927, 8163. 



Legion AGRION de Selys. 



All the fossil species of this group, both in Europe and America, have 

 been referred to the genus Agrion, which is by far the richest of its mem- 

 bers at the present day. 



AGRION Fabricius. 



This genus, in recent times one of the largest and most cosmopolitan 

 of the legion to which it belongs, is represented in the rocks by a single 

 species in Europe, A. aglaope Heer from Oeningen, and the two species 

 from America here described. Besides these a single immature species has 

 been found in Europe (Oeningen) and another in x\nierica (Florissant), 

 which are placed in this group as typical of the Agrionina. 



The genus is, as stated, cosmopolitan, but its richest representation is 

 in the tropics, and in the northern hemisphere at least it is more richly de- 

 veloped in the New World. The two species here described from wings 

 are not sufficiently perfect to decide into what subgenus they will fall, but 

 they are certainly closely related to each other and appear to be most 

 nearly allied to Amphiagrion or else to Pyrrhosoma or Erythromma, 



