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The antennæ afford salient secondary sexual differences, as seen in the broadly pectinated antennæ of male bombycine moths, certain saw-flies (Lophyrus), and many other insects.

The mouth-parts, buccal appendages, or trophi, comprise, besides the labrum, the mandibles and maxillæ.

The mandibles.

While the mandibles are generally regarded as composed of a single piece, in Campodea and Machilis there appears to be an additional basal piece apparently corresponding to the stipes of the first maxilla, and separated by a faint suture from the molar or distal joint. In Campodea there is a minute movable appendage figured both by Meinert and by Nassonow, which appears to represent the lacinia of the maxilla (Fig. 48). Wood-Mason has observed in the mandibles of the embryo of a Javanese cockroach, Blatta (Panesthia) javanica, indications of “the same number of joints as in that of chilognathous myriopods, or one less than in that of Machilis.” Also he adds: “In both ‘larvæ’ and adults of Panesthia javanica a faint groove crosses the ‘back’ of the mandible at the base. This groove appears to be the remains of the joint between the third and apical segments of the formerly 4–segmented mandibles.”