HOW ANIMALS EAT. 59 



the Bee tribe, we have a transi- 

 tion between the biting and the 

 sucking Insects the mandibles 

 " supply the place of trowels, 

 spades, pickaxes, saws, scissors, 

 and knives," while the maxillae 

 are developed into a sheath to 

 enclose the long, slender, hairy 

 tongue which laps np the sweets 

 of flowers. In the suctorial But- 

 terfly, the lips, mandibles, and 

 palpi are reduced to rudiments, 

 while the maxillae are the only 

 useful oral organs. These aro 

 excessively lengthened into a 

 proboscis, their edges locking FI. 22. Head of a wsid Bee (A 



. thophora return), front view: 



by means OI minute teeth, SO as compound eyes; 6, clypens; 



to form a central canal, through 

 which the liquid food is pumped 

 up into the mouth. Seen un- 

 der the microscope, the proboscis is made up of innumer- 

 able rings interlaced with spiral muscular fibres. The 



proboscis of the Fly 

 is a modified lower 

 lip ; that of the Bugs 

 and Mosquitos, fitted 

 both for piercing and 

 suction, is formed by 

 the union of four 

 bristles, which are 

 the mandibles and 

 maxillae strangely al- 

 tered, and encased in 

 the labium when not 



Fie. 23. Proboscis of u Butterfly. in US6. 



