118 Psyche [June 



off and intact, might easily lead one to conclude that the sounds 

 were produced by some other organ than the wings. 



The question may well be asked, "Why are the spiracles so 

 modified and complex as Landois considers them?" It must be 

 taken into consideration that the spiracles are comparatively 

 large openings to a very delicate and vital tracheal system, which 

 should be safely guarded at its openings against the entrance of 

 dust particles. In most cases they are protected by a dense growth 

 of hairs but often are not, as for example in the honey bee. The 

 thoracic spiracles of the honey bee are poorly protected exter- 

 nally but within the opening this folded membranous curtain, or 

 so-called vocal membrane, acts undoubtedly as a screen against 

 the entrance of dust, etc. 



The work described in this paper was done in the Entomological 

 Laboratory of Stanford University. 



THE STRIDULATIONS OF TWO INTERESTING 

 LOCUSTID.E. 1 



By H. A. Allard, 

 U. S. Department of Agriculture, Washington, D. C. 



The writer's first night collecting on Plummer's Island, near 

 Washington, D. C, August 25, 1909, made him acquainted, for 

 the first time, with the stridulation of Atlanticus pachymerus 

 Burmeister. It was singing after dark very close to the ground 

 on a dry, rocky, thinly-wooded hillside. The notes of this odd- 

 looking locust have the same lisping character as an Orchelimum. 

 The phrases are brief, but rapidly repeated, with irregular inter- 

 vals of silence intervening, sh-sh-sh-sh-sh — sh-sh-sh-sh — sh-sh- 

 sh-sh-sh. One is reminded of the prolonged, lisping phrases of 

 Orchelimum molossum Rehn. Several times, while watching the 

 insect stridulate by lantern-light, the writer lisped an approach 

 to its notes and got an immediate response. The grayish brown 

 coloration of this locust is well adapted to its environment of dead 



^Identified by Mr. A. N. Caudell of the U. S. National Museum. 



