ORGAN OF SMELL. 



67 



Green dragon-fly (JEshna varia). 



though there is a pair in the first segment of the 

 trunk obvious enough in most caterpillars and grubs, * 

 but seldom observed in perfect insects. It may be 

 seen, however, in the common rove-beetle ( Goerius 

 olens, Stephens), and in the mole-cricket, just be- 

 hind the arms. From some experiments of Huber, 

 however, it appears not improbable that we have still 

 much to learn respecting the upper spiracles, at least 

 in bees. Swammerdam had ascertained the existence 

 of three pair of spiracles in the chest, and seven in 

 the abdomen of bee pupae ; and Huber, anxious to 

 learn whether these were continued in the adult state. 



* See Insect Transformations, pp. 138, 175, 200 



