AN INTERESTING FEATURE IN THE VENATION OF 



HELICOPSYCHE, THE MOLANNIDAE, AND THE 



LEPTOCERIDAE. 



By Cornelius Bettex, Lake Forest College. 



The conclusions recorded in a recent paper by Prof. 

 Martynov* regarding the venation of the Trichopterous genus 

 HeHcopsyche lead me to anticipate here one of several somewhat 

 revolutionary views on the venation of the Trichoptera to which 

 I have come during the progress of work on a rather extended 

 report on that order of insects. 



For the sake of comparison a figure is here given of the 

 venation of the fore wing of Rhyacophila (Fig. 1), representing 

 an extremely primitive t3^pe. The homologies indicated in 

 this figure are so simple as to require no comment except as 

 regards the branches of subcosta (Sc) and of cubitus and the 

 anals. None of these is here considered and attention is directed 

 only to radius which in this genus appears in absolutely primi- 

 tive condition, that is, with Ri running free to the margin and 

 with the radial sector (Rs) dichotomously branched. In very 

 many Trichoptera there is a cross vein from R3 to R4 setting 

 off what is called the discal cell. Near the base of cell R4 (the 

 cell bounded by R4 and Ro) there is indicated a very small 

 corneous point which is present in the vast majority of Tri- 

 chopterous wings. 



luA 



'a 



Fig. 1. Venation of fore wing of Rhyacophila sp. 



Martynov reaches the conclusion that radius is also found 

 in practically the typical condition in HeHcopsyche (Fig. 2), 

 that is, that cell R4 in both fore and hind wings is not obliter- 

 ated by the fusion of R4 and R5 as might at first sight appear 

 to be the case. 



*Martynov, A. B. On two Collections of Trichoptera from Peru. Annuaire 

 du Musee Zool. de I'Acad. Imperiale des Sci. de St. Petersburg. Vol. 17 (1912), 

 40 pp., Figs. 1-59. 



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