56 ORGANS OF THE LEPIDOPTERA. 



manner as the laminae of a feather, and capable of 

 being united into an air-tight canal, or of being 

 instantly separated, at the pleasure of the insect. 



The formation of mouth we have now been con- 

 sidering is totally different from that of the Cole- 

 optera, or Hymenoptera, formerly described. The 

 mandibles have undergone a change : they no longer 

 appear as powerful instruments for seizing or for 

 cutting ; and the maxillae exhibit a still greater me- 

 tamorphosis, and have become converted into the 

 curious tubular apparatus through which the honey 

 is imbibed. I do not of course mean that the maxillas 

 of the butterfly were ever like those of the beetle : 

 by the word metamorphosis, I merely mean that a 

 difference is observed, and not that the one ever 

 becomes converted into the other. These maxillae 

 are very singular in their structure, and you can, by 

 taking a pin, and applying it to those of any butter- 

 fly, satisfy yourself that it is composed of two dis- 

 tinct tubes. Now, a question naturally arises, of 

 what use are the two outer tubes, when the central 

 one formed by their union is the only one through 

 which the fluid passes ? To explain the cui bono of 

 any point in animal physiology is, in our imperfect 

 state of knowledge, a difficult undertaking ; but I 

 am inclined to think that they are of service in pro- 

 tecting the central one from the pressure of the 



