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. [Illustration: 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. ] In the adult Panorpidæ the lingua is a minute, simple lobe. [Illustration: FIG. 74.—Section through head of a carabid, _Anopthalmus telkampfii_: _br_, brain; _f. g_, frontal ganglion; _soe_, subœsophageal ganglion; _co_, commissure; _n. l_, nerve sending branches to the lingua (_l_); _mn_, maxillary nerve; _mx_, 1st maxilla; _mm_, maxillary muscle; _mx′_, 2d maxilla; _mt_, muscle of mentum; _le_, elevator muscle of the œsophagus; _l_ of the clypeus, and a third beyond raising the labrum (_lbr_); _eph_, epipharynx; _g_, _g_, salivary glands above; _g_^2, lingual gland below the œsophagus (_oe_); _m_, mouth; _pv_, proventriculus; _md_, mandible. _A_, section passing through lingual gland (_g_^2). ] In the larval Trichoptera the spinneret is well developed, and in structure substantially like that of caterpillars, and it is plainly the homologue of the hypopharynx, receiving as it does the end of the silk-duct. In the adult Trichoptera the hypopharynx is a very large, tongue-like, fleshy outgrowth, and is, both in situation and structure, since it contains the opening of the silk-duct, exactly homologous with the hypopharynx of insects of other orders, being somewhat intermediate between the fleshy tongue or lingua of the mandibulate insects, especially the Neuroptera, and the hypopharynx of the bees (Fig. 86). Lucas describes and figures it under the name of “haustellum,” but does not homologize it with the hypopharynx. The caddis-flies have been observed to drink water and take in both fluid and fine particles of solid food, and to use the haustellum for this purpose, the end being provided with minute sense-organs like those on the first maxillary lacinia, and possibly of a gustatory nature. [Illustration: