BEETLES. 95 



Among beetles, the genus Copris, " particularly," says 

 Newport, " Copris molossus, in which I first remarked 

 it, have the antennae composed of ten joints, the last 

 three of which form tlie knob or club with which it is 

 surmounted. 



" When the insect is in motion, these plates or audi- 

 tory organs, if we may be allowed so to call them, are 

 extended as wide as possible, as if to direct the insect 

 in its course ; but upon the occurrence of any loud but 

 sudden noise are instantly closed, and the antennae 

 retracted as if injured by the percussion, while the 

 insect itself stops and assumes the appearance of death. 

 A similar use of the antennae is made by another family, 

 Geotrupidae, which also act in the same manner under 

 like circumstances. 



***** 



"These facts, connected with the previous experi- 

 ments, have convinced me," he says, " that the antennae 

 in all insects are the auditory organs, whatever may 

 be their particular structure ; and that, however this 

 is varied, it is appropriated to the perception and 

 transmission of sound." f 



Will has made some interesting observations on 

 some of the Longicorn beetles (Cerambyx), which 

 tend to confirm this view. These insects produce 

 a low shrill sound by rubbing together the prothorax 

 and the mesothorax. The posterior edge of the 

 prothorax bears a toothed ridge, and the anterior end 

 of the mesothorax a roughened surface, and when these 

 are rubbed together, a sound is produced something 

 like that made by rubbing a quill on a fine file. 



* Newport, "On the Antennae of Insects," Transactions of the 

 Entomological Society, 1836-40, vol. ii. 



