ANATOMY AND PHYSIOLOGY 



37 



insects is a simple plate, hinged to the clypeus and moving up 

 and down, though capable of protrusion and retraction to some 

 extent. It covers the mandibles in front and pulls food back 

 to these organs. On the roof of the pharynx, under the la- 



FIG. 44. 



Mouth parts of a cockroach, Ischnoptera pennsylvanica. A, labrum; B, mandible; 

 C, hypopharynx; D, maxilla; E, labium; c, cardo; g (of maxilla), galea; g (of labium), 

 glossa; I, lacinia; Ip, labial palpus; m, mentum; mp, maxillary palpus; p, paraglossa; 

 pi, palpifer; pg, palpiger; s, stipes; sm, submentum. B, D and E are in ventral 

 aspect. 



brum and clypeus, 'is the epipharynx; this consists of teeth, 

 tubercles or bristles, which serve in some insects merely to 

 hold food, though as a rule the epipharynx in mandibulate 

 insects bears end-organs of taste (Packard). 



The mandibles, or jaws proper, move in a transverse plane, 

 being closed by a pair of strong adductor muscles and opened 

 by a pair of weaker abductors. The mandible is almost 

 always a single solid piece. In herbivorous insects (Fig. 

 45, A) it is compact, bluntly toothed, and often bears a molar, 

 or crushing, surface behind the incisive teeth. In carnivorous 



