110 THE VITAL FUNCTIONS. 



are, in like manner, enabled, from a simple inspec- 

 tion of the shape of the teeth, to form tolerably 

 accurate ideas of the kind of food on which the 

 insect naturally subsists.* 



Above, or rather in front of the mandibles, 

 is situated the labrum, or upper lip (u). It is 

 usually of a hard or horny texture, and admits of 

 some degree of motion ; but its form and direction 

 are exceedingly various in different tribes of in- 

 sects. The lower pair of jaws (j), or maxillce, as 

 thev have been termed, are behind the mandibles, 

 and between them is situated the labium, or lower 

 lip (l), which closes the mouth below, as the 

 lahnun does above. In the grasshopper, each max- 

 illa consists of an outer and an inner plate (o and i). 

 The jaws of insects are confined, by their articula- 

 tions with the head, to motions in a horizontal 

 plane only, so that they open and close by lateral 

 movements, and not upwards and downwards, as is 

 the case with the jaws of vertebrated animals. The 

 maxillae are, in most cases, employed principally 

 for holding the substances on which the dividing 

 or grinding apparatus of the mandibles is exerted. 

 The parts denominated Palpi or Antenmilce (p, q), 

 are probably organs of sense : they consist of 

 jointed filaments, or processes, attached to different 

 parts of the mouth, and most usually to the maxillae 

 and the labium ; the former (p) being termed the 

 maxillary, and the latter (q) the labial palpi. In 

 addition to these parts, another, which, from its 

 supposed use, has been denominated Glossa, or 

 tongue (g), is also generally found. 



* See a memoir by Marcel des Serres, in the Annales du Museum 

 d'Hist. Nat. xiv. 56. 



