2 University of Michigan 



to do with the true Agriogomphus of de Selys. The species 

 referred to Agriogomphus by the three later authors above 

 mentioned belong to an undescribed genus which I propose 

 describing in this paper under the name ARCHAEOGOM- 

 PHUS, new genus, type Agriogomphus hamatus Williamson. 



Archaeogomphus, new genus 



Belonging to that group of genera (not necessarily closely 

 related, inter se) oi the legion Gomphus which possesses num- 

 erous unspecialized cross-veins between Al^.g and jM^. The 

 distribution of characters within the group and the artificial 

 key to the genera which I have previously published^ should 

 be revised, since Agriogomphus as used in that paper is really 

 Archaeogomphus, and the characters of the true Agriogom- 

 phus are not included therein. 



Distribution of Characters Within the Group 



1. Stigma with a weak brace-vein: Agriogomphus, Cyano- 



gomphus, Ischnogomphiis. 

 la. Stigma without a brace-vein: Archaeogomphus, Epigom- 

 phns, Lepto gomphus, Macrogomphus, Microgomphus. 



2. Basal antenodal of second series present : Agriogomphus, 



Cyanogomphus, Epigomphus, Ischnogomphus, Lepto- ^ 

 gomphus, Macrogomphus. 

 2a. Basal antenodal of second series not present: Archaeo- 

 gomphus, Leptogomphus, Microgomphus. 



3. Distal thickened antenodal the fifth: Archaeogomphus, 



Agriogomphus, Cyanogomphus, Ischnogomphus, Mi- 

 crogomphus. 



3 Occasional Papers of the Museum of Zoology, University of Michigan, Num- 

 ber 52, April 17, 1918. 



