MOUTH OF THE BUGS. 17 



composed of the labium and its palpi soldered toge- 

 ther, and turned inwards so as to form a tube. The 

 sides of the slit above mentioned have a rather wider 

 space between them towards the point where the ros- 

 trum springs from the head, and this is closed up by 

 a long, transversely wrinkled organ, the representative 

 of the labrum or upper lip. Within the tube we find 

 four bristles, which, as in the Flies, represent the man- 

 dibles and maxillae ; these can be pushed out of the 

 jointed sheath, and as they are sharp at the point, 

 they are employed in piercing the tissues of living 

 plants and animals, upon whose juices these little 

 creatures feed, the solid rostrum at the same time 

 furnishing the support necessary to enable such deli- 

 cate bristles to penetrate into the firm tissues. 



We have thus, as briefly as possible, traced the 

 structure of the mouth in different groups of insects, 

 and indicated the mode in which these apparently 

 dissimilar organs are produced by the modification of 

 the same essential parts. Brief as these observations 

 have been, I am not without some fear that they 

 may be subject to the dreadful imputation of dryness, 

 and if so, my justification must be, that it is quite 

 impossible entirely to avoid this fault, and at the same 

 time to give a clear idea of matters of such pure 

 detail ; and in fact the brevity with which the subject 

 has been treated is of itself inimical to that charming 

 lightness with which many popular writers on science 

 dilute their scanty materials. The reader may take 

 it for granted, however, that no knowledge worth 

 having can be got without some little effort, and he 

 will find that by taking the trouble of reading through 

 the preceding observations, his progress through the 

 study of the classification of insects will be mate- 



