NERVES — SENSES : SIGHT. 



303 



to its perception by the eyes of their associates, just as the 

 chirping of a cricket is adduced in favour of the hearing of 

 its fellows. Amongst insects, the Lampyridoe, or glow-worms. 



Male and Female Glow-worm. 



and the ElateridcB, are the only famiUes which are decidedly 

 proved to possess this faculty, although it has been asserted 

 to prevail in the Fulgorida, and some isolated species of 



Fulgora latcrnana. 



other groups ; but there is no distinct evidence of its ex- 

 istence in these latter insects. 



(b) The Sense of Hearing. — Linnajus describes insects in 

 general as " Muta nisi alio proprio instrumento, sonora ; 

 Surda stridorem aetheris licet percipiant." From many facts, 

 however, it is evident that insects distinguish sounds in some 

 manner or other, although the greatest uncertainty prevails 



