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 {96}undivided mentum, and closes the mouth beneath or behind, according as the position of the head varies. In most Insects the labium appears very different from the maxilla, but in many cases several of the parts corresponding to those of the maxilla can be clearly traced in the labium. [Illustration: FIG. 52.—Maxilla and lower lip of Coleoptera. A, Maxilla of _Passalus_: _a_, cardo; _b_, stipes; _c_, palpiger; _d_, palpus; _e_, inner or inferior lobe or lacinia; _f_, outer or superior lobe or galea: B, Labium of _Harpalus caliginosus_: _a_, mentum; _b_, hypoglottis; _c_, palpiger (support of the labial palp); _d_, palp; _e_, ligula; _f_, paraglossa.] The mentum is an undivided, frequently very hard, piece, continuous with either the submentum or the gula, and anterior to this are placed the other parts, viz. the labial palpi and their supports, the palpigers; beyond and between these exists a central piece (Fig. 52, B, _e_), about whose name some difference of opinion prevails, but which may be called the ligula (languette of French authors), and on each side of this is a paraglossa. In the Orthoptera the single median piece—the ligula of Coleopterists—is represented by two divided parts. In some Insects (many Coleoptera) there is interposed between the mentum and the palpigers a piece called the hypoglottis (Fig. 52, B, _b_). It is not so well ascertained as it should be, that the pieces of the lower lip bearing the same names in different Orders are in all cases really homologous, and comparison suggests that the hypoglottis of Coleoptera may possibly represent the piece corresponding to the mentum of Orthopterists, the so-called mentum of beetles being in that case the submentum of Orthopterists.