THE IDENTITY OF TWO ODONATA FOSSILS. 1 



By Dr. F. Ris. 



The following observations are based on the two species of 

 Odonata fossils described by Scndder in Bulletin 93 U. S. Geolog- 

 ical Survey and figured on Plate 1, figures 1 and 2. 



I. Stenogomphus carletoni Scudder. 



The first impression of the wing is. that it is a Gomphine ; 

 more especially, that it is much like Progomphus. This, in fact, 

 was the conclusion reached by De Selys and Hagen, who individ- 

 ually determined the species as related to Progomphus from sep- 

 arate figures furnished them by Scudder. 



But this view does not stand upon closer examination. It is 

 then found to be a Libellulid, more specifically a Corduline, prob- 

 ably nearer to Aeschnosoma than to anything else; Neocordulia, 

 Neurocordulia and Platycordulia also may be compared. The 

 following are my reasons for this determination : 



A. — The Gomphine supposition. — In favor of this view we have: The 

 antenodals of the costal and subcostal series are not coincident. The 

 triangle is much like Progomphus, Gomjihoide*, or Ictinus; the cross- 

 ing- by three nervides is not common for a Libellulid. indeed none of the 

 Lioellulince known to me possesses a triangle in the forewing crossed 

 in Y-fashion ; the angulate distal side of this triangle too is much like 

 many Gompflince, only I should want for such a condition of the distal 

 side of the triangle at least a trace of a "triangular supplement" 

 (Williamson) ; no such supplement is figured by Scudder. 



Against the Gomphine supposition, there are the following argu- 

 ments : 



1 ) The present paper originated through my casual inquiry as to the 

 probable relations and position of Stenogomphus carletoni Scudder, if Dr. 

 Needham's statement " — it is in fact a Libellulid in every line" (Proc. U. S. 

 Nat. Mus., 26, p. 701, 1903), which unfortunately was not further elucidated, 

 was to be accepted. Dr. Ris examined a figure of the fossil and in a letter dated 

 April 6th summarized his views for sustaining Dr. Needham's opinion. Dr. 

 Ris' remarks seemed to me of such moment to Odonatologists that I requested 

 his permission to transcribe the letter (of which he retained no copy) for 

 publication, which was readily granted. As far as possible I have adhered to 

 the original letter ; a few changes were unavoidable, owing to the exigencies 

 of publication. — R. A. Muttkowski. 



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