Occasional Papers of the Museum of Zoology i;j. 



Amphitornus coloradns (Thomas). — Medora, July 30, 1920, 

 3 females; Amidon, Aug. 21-28, 1920, 8 males, 5 females. 



At Medora this species was found among sparse, dry vege- 

 tation on the sides of a clay butte. At Amidon it was fairly 

 common on the upland plains among the characteristic vege- 

 tation of dry grasses, clumps of Artemisia, etc. Specimens 

 were taken on the top of Black Butte, on the plains at the 

 base of Chalky or White Butte, among the "breaks" of the 

 Bad Lands, and in pastures and fields near town. While quite 

 numerous, on account of their great agility specimens were 

 seldom taken except by sweeping, or in the case of the males 

 by tracing them down by means of their stridulation. 



This consists of a series of rather slow notes — zzzzz — zzzzz 

 — zzzzz — zzzzz — repeated at the rate of approximately three in 

 two seconds. The sound is apparently produced as follows: 

 during each separate note the closed femur and tibia make 

 one complete movement across the tegmina from the highest 

 to the lowest position which they occupy in stridulation, and 

 back to the highest, but this is not accomplished in a single 

 uniform motion. During this movement through a compara- 

 tively large angle the leg is vibrated very rapidly back and 

 forth over a much smaller arc at the estimated rate of 15 to 

 20 vibrations per second. The resulting note is rather faint. 



Opeia obscura (Scudder). — Buford, July 23, 1920, i male, 

 2 juveniles; Medora, July 30-Aug. 3, 1920, 26 males, 12 

 females, i juvenile; Amidon, Aug. 21-28, 1920, 23 males, 54 

 females. 



At Buford this species was scarce among dry grass and 

 Artemisia patches on the sides of a barren hill ; at Medora it 

 was common in similar situations. In the vicinity of Amidon 

 it was common and in places abundant on dry grassland; on 

 the plains in the vicinity of town, on the slopes and summits 



