25 



Landois are produced in two ways: first, by rubbing the inner surface of the hind 

 legs against the outer surface of tlie elytra ; and, second, by rubbing together 

 the upper surface of the front edge of the wings and the under surface of the 

 elytra. According to Landois,* the inner surface of the hind femur is fur- 

 nished along the lower margin with a longitudinal row of minute, elegant, 

 lancet-shaped, elastic teeth, varying in number from eighty-five to ninety- 

 three, which are scraped across the nerves of the elytra, thus producing 

 sound. 



The species which employ the first method stridulate while at rest, pro- 

 ducing a low buzzing sound ; this is the usual, I hough not universal, method of 

 the Stenohothri. Those Acridida which produce sounds by rubbing their wings 

 and elytra together, stridulate only during flight, and, as remarked by Mr. Scud- 

 der,t " are nearly all confined to the genus CEdipoda," producing a sharp crack- 

 ling sound, resembling the noise of burning stubble, f Each species appears to 

 have its peculiar note, so that, having a knowledge of the Orthoptera of a 

 given locality, we can at once distinguish the species by the sound made. 

 The soft, pattering sound made by some species of Acridium and Culoptenus 

 during flight is probably due simply to the beating of the air by the wings, 

 as it does not appear to be confined to sex ; the males only of grasshoppers 

 being furnished with apparatus for producing notes. 



* Zeitschrift fiir wissenscbaft. Zoolog., XVII, 1867, 117. 

 t Proc. Bost. Soc. Nat. Hist., XI (1867), 313. 



I From this fact we may safely couclude that the species mentioned in the Boole of 

 Joel was an CEdqwda, and most probably Q^dipoda (Pachytylns) migratoria. 

 4a 



