332 PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



ters (flies), and the hymenopters (bees and ants), al- 

 though these last are intermediate. Of these two kinds 

 of mouth parts the former is undoubtedly the original 

 and normal, of which the latter must be regarded as an 

 extreme modification, for the mandibulate form alone 

 is found in the larval state (e. g., caterpillars) and in 

 early geological times. 



Normal Mouth Parts. — Taking, then, the orthop- 

 ter, or grasshopper, or else a beetle, as example, there 



are six movable mouth 

 parts ; but as four of 

 these are in pairs, we 

 may say there are four 

 kinds. These are the 

 labrum (so-called upper 

 lip), the two mandibles, 

 the two maxilla, with 

 their jointed append- 

 ages," and the labium 

 (lower lip), with its 

 jointed appendages. 

 Sometimes there is an 

 elongation of this last 

 called the tongue. 

 These are seen in place 

 in the beetle (Fig. 212), 

 and the same parts in a 

 grasshopper separated 

 to display their forms 

 and position in Fig. 213. Looking directly at the mouth 

 of the grasshopper or beetle, their relative position and 

 direction of motion is shown in the diagram (Fig. 214). 

 The food is gathered by the maxillary and labial palpi, 

 is placed between the jaws (mandibles and maxillte), 

 pressed together between the upper and lower lips, and 



Fig. 212. — Head of a beetle seen from 

 behind : lb, labium ; lp y labial palpi ; 

 m m, mandibles ; mx, maxilla? ; mp, 

 maxillary palpi ; Ibr, labrum. 



