\\ \ n.\n \\i. PHYSIOI <",", 





I he UMial Malcmenl [fl that llr iouth p. 



namely, Mandibles, maxilla- and Itibium. As a m.r id. tin 



four pairs, counting the .\///vr////i;//r/\ which are evident in 'I hv anura 

 and Collembola. become vestigial in Hdenmietabnla, and di~app> 

 the most spec iali/ed I lolonidahola. The mandilnilate. or pri: 

 type (Fig. 45), from which the suctorial, or secondary type, 

 derived, will be considered first. 



Mandibulate Type.- The labrum, or upper lip, in biting insect- 

 simple plate, hinged to the clypeus and moving up and down; th 

 capable of protrusion and retraction to some extent. It covers the man- 



FIG. 45. Mouth parts of a cockroach, Parcoblatta Pennsylvania. A, labrum; B, 

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

 labium), glossa; I, lacinia; lp, labial palpus; m, mentum; mp, maxillary palpus; p, paraglossa; 

 pf, palpifer; pg, palpiger; 5, stipes; sm, submentum. B, D, and E are in ventral aspect. 



dibles in front and pulls food back to these organs. On the roof of the 

 pharynx, under the labrum 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 labrum does not represent a pair of 

 primary appendages. 



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. 46, A) it is compact, bluntly toothed, and 



