66 



Annals Entomological Society of America [Vol. VI, 



That this view is correct seems to admit of no doubt. In 

 the American species {H. borealis Hag.) the relations are entirely 

 clear. R5 leaves R4 at nearly a right angle and then again 

 turns sharply to the wing margin; the cross vein rm meets the 

 vein at the latter angle, and is in a nearly horizontal position. 

 One might therefore easily be deceived into thinking that the 

 cross vein rm and the distal part of R5 with which it is in direct 

 line together constitute a branch of media. A failure to recog- 

 nize the true relation has forced most authors to leave this vein 

 unidentified in their figures. The exact position of the base of 

 R5 varies somewhat within the genus and also within the species ; 



^it-'f 





Fig. 2. Venation of Helicopsyche borealis. 



in specimens of H. borealis (Fig. 2 and Fig. 3a) the cross vein rm 

 is left intact though out of the usual position as already shown, 

 in Martynov's figure (1. c, Fig. 2, copied in Fig. 3b) of H. 

 miiiuscula the angle in R5 just touches M1+2 so that the cross 

 vein rm is obliterated and its function is assumed by the base 

 of Ro, in Ulmer's figure of H. borealis (Genera Insect. Fasc. 60, 

 pi. 11, fig. 98, copied in Fig. 3c) the base of R5 has migrated 

 still farther back so as to be still more deceptive in its resem- 

 blance to the cross vein which it has displaced. Ulmer has 

 recently described some related fossil genera in one of which 

 (Palaeohelicopsyche*) the female has the cross vein rm present 

 while it has been displaced in the male. 



*Ulmer, Georg. Die Trichopteren des baltischen Bernsteins. Schriften der 

 physikalisch-okonomischen Ges. zu Konigsberg. Beitrage zur Naturkunde 

 Preussens. Heft 10 (1912), p. 308. 



