T. D. A. Cockerell — Descriptions of Tertiary Insects. 73 



crossed ; Micromerus has quadrangle usually crossed and sub- 

 quadrangle with one or two cross-veins. Paraphlebia, men- 

 tioned above, of course is entirely different from Trichocnemis 

 in all other characters." 



With regard to the vertical subnodus, Mr. Williamson writes : 

 " Xanthagrion erythroneurum has it vertical; Erythromma 

 najas (especially the hind wing) nearly or practically so ; it is 

 nearly vertical in the American Oxyagrion, Argia, Hyponeura 

 and Tschnura (at least some of the species). This character, 

 I believe, appears independently many times, and is no crite- 

 rion in itself" of generic relationships. 



Fig. 3. Trichonemis aliena. 



Except for the crossed subquadrangle, Mr. Williamson says 

 that he sees no objection to referring T aliena to Hespera- 

 grion. "The form of wing is similar; the quadrangle, sub- 

 quadrangle and the relations of their parts to the antenoclals 

 are similar ; the origin of M 2 is similar ; and the length and 

 direction of the subnodus are not far out of the way. I believe, 

 in this view, that T. aliena [Scudder's type] is a hind wing." 

 Mr. Williamson further adds : 



" I have compared Scudder's figure with wings of Calicne- 

 mis, Flemicnemis {Leptocnemis), Platycnemis and Tatocne- 

 mis, — some of the genera usually associated with Trichocnemis. 

 If Scudder's figure of wing is correct in outline, T aliena is 

 not similar to any of the above genera. In arrangement of 

 veins at distal end of quadrangle, T aliena is most similar to 

 Hemicnemis (which genus, of the whole group, has the quad- 

 rangle most dissimilar) and Calicnemis. In arrangement of 

 veins at base of quadrangle it most resembles Platycnemis. 

 Moreover, in above genera, only in Platycnemis is the sub- 

 nodus nearly or quite vertical. In Tatocnemis (which is very 

 dissimilar in many characters), the subnodus is very short." 



Our specimen, like Scudder's, has eleven postnodal cross- 

 nervures. The first cross-nervure beyond the stigma is forked 

 below. There are three cells between M x and M 2 before the 

 doubling begins (four in Scudder's t} 7 pe). There is a very dis- 



