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In the Odonata the lingua is a small, rounded lobe, as also in the Ephemeridæ; in the nymph, however, of Heptagenia (Fig. 72) it is highly developed, according to Vayssière, who seems inclined to regard it as representing a pair of appendages. The tongue in Hemiptera is said by Léon to be present in Benacus griseus (Say) and to correspond to the subgalea of Brullé or hypodactyle of Audouin (Fig. 73), but this appears to correspond to the labium proper, rather than a true lingua, the latter not being differentiated in this order. In the Coleoptera the lingua is rather small. In beetles, as Anopthalmus (Fig. 74), it forms a setose lobe; and a well-developed nerve, the lingual nerve, passes to it, dividing at the end into several branches (n-l). In Sialis the lingua is short, much less developed than usual, being rounded, and bears on the edge what appear to be numerous taste-hairs, like those on the ends of the maxillary and labial palpi.

Fig. 73.—A, labium of Zaitha anura. B, of Z. margineguttata. C, of Gerris najas: mt, mentum; lp, labial palpi; sg, subgalea; l, lacinia (= intermaxillare and præmaxillare of Brullé); g, galea.—After Léon.