Occasional Papers of the Museum of Zoology 5 



d. Anal area in the hind wings three cells wide. 

 e. One cubito-anal cross-vein in addition to the 

 inner side of the subtriangle. . .Lcptogoinphus. 

 ee. Two cubito-anal cross-veins in addition to the 



inner side of the subtriangle Bpigomphiis. 



dd. Anal area in the hind wings four or more cells 

 wide Macrogomphus. 



Archaeogomphus is an isolated type without apparent re- 

 lationships. The strikingly unsymmetrical forking of M^^o 

 and M3, which occurs also in Leptogomphus and Microgom- 

 phus of the Oriental fauna and Epigomphus of the Neotrop- 

 ical, is found scarcely or not at all in other genera of the legion 

 Gomphus, a symmetrical or nearly symmetrical forking being 

 the rule. The male of the type species, hamatus, is unique in 

 the form of the tenth abdominal segment ; this has the dorsum 

 armed basally on either side with a strong interno-posteriorly 

 directed hook and produced apically in a long snout-like pro- 

 jection which is more than twice as long as the rudimentary, 

 flap-like, superior appendages; the inferior appendage is still 

 more rudimentary, and these appendages have no function as 

 grasping organs. A grio gomphus infans Ris is an Archaeo- 

 gomphus; and Needham's figure 27, in A Geneologic Study 

 of Dragon-fly Wing Venation, is of an undescribed species of 

 the same genus. 



The venation of Archaeogomphus hamatus is figured in 

 my paper describing the species (Occ. Papers of the Mus. of 

 Zool., No. 59). In that paper on page 11, first line, for /tco- 

 thirds read tzvo- fifths; and in the explanation of Plate I, first 

 line, insert lozvcst after 10 and before magnification. 



Agriogomphus is closely related to Cyanogomphus and 

 Ischnogomphus, from both of which it is separated at once by 



