8 University of Michigan 



are certainly primitive gomphine wing characters. When we find 

 a basal position of ac and an unsymmetrical forking of Mj-, and 

 M3 associated with these two characters in the same wings it may 

 safely be assumed that the basal position of ac and the unsym- 

 metrical forking are relatively primitive characters also. 



1. The Epigomphus series. — This includes the following genera 

 previously included in the grand genus Gomphus of de Selys: 

 Archaeogomphus, Agriogomphus, Cyanogomphus, Epigomphus, 

 Ischnogomphus, Leptogomphus, Macrogomphus, and Microgom- 

 phus. In this series alone, in Archaeogomphus, and to a lesser 

 extent in Microgomphus, is a four-sided triangle found in the sub- 

 family. (It is indicated also in the hind wing of the single figure 

 I have of the venation of Neogomphus.) At the other end of the 

 series from Archaeogomphus is the more densely veined Macro- 

 gamphus quadratus with its strikingly curved sectors. The series 

 is distinguished by free triangles, supratriangles, and subtriangles, 

 and numerous cross-veins between Mi_3 and M4. In the higher 

 members of the series ac moves distally, Mi_2 and M3 form a sym- 

 metrical fork, and there is an increase in density of wing venation. 

 In the next series specialization by addition has been carried still 

 farther. Of the Epigomphus series three genera with twenty-two 

 species occur in the Oriental Region and five genera with sixteen 

 species occur in the Neotropical Region. 



2. The Progomphus series. — This includes the grand genera 

 Progomphus and Gomphoides of de Selys and Diaphlebia and 

 Desmogomphus. Genera of this series may be recognized by 

 having the triangles, supratriangles, and subtriangles more or less 

 cross- veined , by dissimilar triangles and subtriangles in fore and 

 hind wings, the triangles of the fore wings being relatively 

 shorter and of the hind wing relatively longer; by the absence 

 of sectors of Rs and M4 and of strongly developed trigonal 

 supplements, and by the outer side of the triangles not distinctly 

 concave. 



