BUTTERFLIES OF MONTANA. 143 



Antennae usually with a long club which is bent at a considerable dis- 

 tance from the tip; males almost invariably with a costal fold, 

 never with a brand. Skippers with a costal fold and their allies 



Hesperiinae, P. 143 

 Subfamily Hesperiinae. 



In this subfamily are included the larger of the common skippers, as 

 well as some that are of smaller size. Most of the species are dark 

 brown, marked with white or translucent, angular spots. The antennae 

 usually have a long club, which is bent at a considerable distance from 

 the tip. The venation is shown in Fig. 102. The most distinctive feature 

 is exhibited by the males alone, but is lacking in some species. This 

 consists in a fold in the fore wing near the costal margin, which forms a 

 a long, slit-like pocket, containing a sort of silky down. This is a accent 

 organ. Tubular scales, the androconia, open into it. This pocket is 

 difficult to see when the pocket is closed. 



Key to Genera. 



1. Fore wings with a broad, bright yellow band near the middle " 2. 

 Fore wings not crossed by a broad, bright yellow band 3. 



2. With a large silvery-white spot in the center of the lower side of th& 



hind wings Epargyreus, P. 14S 



3. Upper surface of wings black or brown, with a few white spots on 



the fore wings or with none, hind wings not checkered with white 4. 

 Both fore and hind wings checkered with many white spots 9. 



4. Club of antennae hooked; anal angle of hind wings slightly pro- 



longed Cocceius, P. 144 



Club of antennae sickle-shaped ; anal angle of hinds wings rounded 8. 

 Club of antennae thickened at the end, which is obtuse and bare 5. 



5. No costal fold in the male Hesperopsis, P. 

 A costal fold in the male 6 - 



G. A pair of long lobes covering a bare hollow at base of addomen of male 



Scelothrix, P. 



These lobes short or absent 7. 



7. Hind tibiae with a hair pencil Heliopetes 



Hind tibiae without a hair pencil Pyrgus, P. 



8 Fore wings entire, with a costal fold in the male; costal fold short, 



less than half the margin Pholisora, P. 



Costal fold of the male long; over half the margin 10. 



9. The white spots in the band just beyond the middle of the fore wings 



much broader than high Pyrgus, P. 



The white spots in the band just beyond the middle of the fore wings 



but little if any broader than high Scelothrix, P. 



10. Third joint of palpi moderate, less than twice as long as wide 



Thanaos 



Genus EPARGYREUS. 

 Key to Species. 



1. Hind wings more or less produced or tailed at the anal angle 

 Hind wings produced not tailed 



2. Under side of hind wings with a silver band in the middle tityrus 



