MOUTH-PARTS 



95 



does the mandible, even in the mandibulate Insects. It can 

 scarcely be detected in some, while in others, as in the male stag- 

 beetle, it may attain the length of the whole of the rest of the 

 body ; its form, too, varies as much as its size ; most usually, 

 however, the pair of mandibles are somewhat of the form of 

 callipers, and are used for biting, cutting, holding, or crushing 

 purposes. The mandibles are frequently armed with processes 

 spoken of as teeth, but which must not be in any way confounded 

 with the teeth of Vertebrates. The only Insects that possess an 

 articulated tooth are the Passalidae, beetles armed with a rather 

 large mandible bearing a single mobile tooth among others that 

 are not so. Wood Mason and Chatin consider the mandibles to 



FIG. 51. Mandibles, 

 maxillae, and labium. 

 of Locusta viridis- 

 sima : A, mandibles ; 

 B, maxillae (lateral 

 parts) and labium 

 (middle parts) united : 

 a, cardo ; b, stipes ; 

 c, palpiger ; d, max. 

 palp. ; e, lacinia ; /, 

 galea ; g, sxibmentum ; 

 h, mentum ; i, pal- 

 piger ; k, labial pal- 

 pus ; I, ligula ; m, 

 paraglossa (galea) ; n, 

 lacinia ; o, lingua. 



d 



be, morphologically, jointed appendages, and the latter authority 

 states that in the mandible of Embia he has been able to distin- 

 guish the same elements as exist in the maxillae. In aculeate 

 Hymenoptera the mandibles are used to a considerable extent 

 for industrial purposes. 



The maxilla is a complex organ consisting of numerous pieces, 

 viz. cardo, stipes, palpiger, galea, lacinia, palpus. The galea and 

 lacinia are frequently called the lobes of the maxilla. The 

 maxilla no doubt acts as a sense organ as well as a mechanical 

 apparatus for holding ; this latter function being subordinate to 

 the other. In Fig. 68, p. 122, we have represented a complex 

 maxillary sense-organ. 



The labium or lower lip has as its basal portion the tin- 



