216 



NATURAL HISTORY. 



[CH. XV. 



the terminal lobes is also transversely ridged, which 

 must necessarily give greater facility to the ac- 

 tions of the organs, by enabling it to adapt itself 

 more readily to rough surfaces (Fig. c). It is es- 

 sential, however, that the mouth should be provided 



Extremity of the sucker of the fly, showing its annulated 

 appearance. 



with some instrument for piercing even the soft 

 substances of which the food is composed, and we 

 accordingly find a fine point (the tongue) arising 

 near the elbowed part of the proboscis, which is for 

 safety lodged in a stronger point (the labrum), both 

 when at rest fitting into the canal of the proboscis, 

 as represented in our figure b. 

 In figure d we have exhibited the mouth in an- 



other position, showing the sharpened upper lip 

 raised from the fleshy proboscis, and in figure e the 

 mouth of the blue-bottlefly is represented, having 

 the tongue disengaged from the superior stronger 

 labrum. 



