36 IOWA STUDIES IN NATURAL HISTORY 



The fringes of the secondaries of this species are pure white, save at the 

 apex and anal angle. 



Arizona, July and August. 



GROUP B 



The second group of the subfamily Hesperiinae is distin- 

 guished from group A by the short cell of the primaries, the 

 form of the antermal club, and the palpi. The cell Is never over 

 two-thirds as long as the wing, and is usually a little less; the 

 antennal club is ovate or fusiform, usually somewhat flattened 

 and more or less curved, but never bent as in most of the genera 

 of group A and never with a distinct apiculus; the palpi are 

 porrect or oblique, either large or with hairy vestiture or both. 

 The only similar palpi in group A are found in the genus Plestia. 



The genera of this group appear to be very poorly denned, 

 owing to the structural variation of the species. If we split to 

 the extent reached by some lepidopterists we can make a genus 

 for practically every species, so the opposite course seems ad- 

 visable, and I have therefore lumped a number of familiar genera 

 to group species which appear to be related. This has resulted, 

 especially in Pholisora, in the association of species which can 

 easily be separated by structural differences, but in all cases 

 these characters show a transition through the several species 

 which causes me to regard them as unreliable for the separation 

 of genera. 



Key to the genera 



1. Secondaries irregular, excavated opposite end of cell and 

 before anal angle ; not trigonate. Vein 2 of primaries near- 

 er base of cell than to vein 3 Systasea 



Not such insects 2 



2. Club of antennae long, slender, not distinctly flattened, and 



scarcely exceeding twice the diameter of the shaft 3 



Club thicker in at least one direction 4 



3. Primaries slightly excavated below apex; humeral angle 



prominent, rounded Eantis 



Apex rectangular; humeral angle normal Xenophanes 



4. Palpi large; third joint conspicuous; vestiture not roughly 



hairy Pholisora 



Palpi moderate to large ; third joint not conspicuous or ves- 

 titure hairy 5 



