Occasional Papers of the Museum of Zoology 7 



Type: Ischnogomphus jessei, new species. 



Remarks: The group of genera of the legion Gomphus of 

 de Selys, which is separated from the other genera of the 

 legion by the possession of numerous cross-veins between 

 AIi_3 and IM^. includes Agriogomphus,'* Cyanogomphus, Epi- 

 gomphus, Ischnogomphus, Leptogomphus, ^lacrogomphus and 

 Microgomphus. 



Distribution of Characters Within the Group 



r. Stigma with a weak brace-vein: Cyanogomphus, Ischnogomphus. 

 la. Stigma without brace-vein: Agriogomphus, Bpigomphus. Lepto- 

 gomphus, Macrogomphus, Microgomphus. 



2. Basal antenodal of second series present: Cyanogomphus, Epi- 



gomphus. Ischnogomphus, Leptogomphus, Macrogomphus. 



2a. Basal antenodal of second series not present : Agriogomphus, Lep- 

 togomphus, Microgomphus. 



3. Distal thickened antenodal the fifth: Agriogomphus, Cyanogom- 



phus, Ischnogomphus, Microgomphus. 

 3a. Distal thickened antenodal the sixth or more distal: Bpigomphus, 

 Leptogomphus, Macrogomphus. 



4. One cubito-anal cross-vein in addition to the inner side of the 



subtriangle: Agriogomphus, Cyanogomphus, Ischnogomphus, 

 Leptogomphus, Macrogomphus, Microgomphus. 



4a. Two cubito-anal cross-veins in addition to the inner side of the 

 subtriangle: Bpigomphus, Macrogomphus, Microgomphus. 



5. One row of postrigonal cells in the front wings : Agriogomphus. 



5a. Two rows of postrigonal cells in the front wings : Cyanogomphus, 

 Bpigomphus, Ischnogomphus, Lcptogomptius, Macrogomphus, 

 Microgomphus. 



6. One row of postrigonal cells in the hind wings: Agriogomphus, 



Cyanogomphus, Bpigomphus. 



6a. Two rows of postrigonal cells in the hind wings: Cyanogomphus, 

 Bpigomphus, Isclinogomphus, Leptogomphus, Macrogomphus, 

 Microgomphus. 



■* Agriogomphus as used in this paper is equivalent to Agriogomphus as used 

 by Needham, A Geneologic Study of Dragonfly Wing Venation, Proc. U. S. 

 National Museum, Vol. XXVI, fig. 27, page 738, and Ris, Odonatenfauna von 

 Argentina, jNIem. Soc. Ent. Belgique, Vol. XXII, p. 72. 



