In the Acrydiidæ (_Melanoplus femur-rubrum_) the tongue is a large, membranous, partly hollow expansion of the base of the labium. It may be exposed by depressing the end of the labium, when the opening of the salivary duct may be seen at the bottom or end of the space or gap between the hinder base of the tongue, and the inner anterior base of the labium, as shown by the arrows in Fig. 70. It is somewhat pyriform, slightly keeled above, and bearing fine stiff bristles, which, as they point more or less inwards, probably aid in retaining the food within the mouth. The base of the tongue is narrow, and extends back to near the pharynx, there being on the floor of the mouth, behind the tongue, two oblique, slight ridges, covered with stiff, golden-yellow hairs, like those on the tongue. The opening of the salivary duct is situated on the under or hinder side of the hypopharynx, between it and the base of the labium, the base of the former being cleft; the hollow thus formed is situated over the opening, and forms the salivary receptacle. [Illustration: FIG. 71.—Section through the anterior part of the head of Anabrus (the mandibles removed), showing the relations of the hypopharynx (_hyp_) to the opening of the salivary duct (_sd_): _g_, galea; _l_, lacinia; _mt_, mentum; _oe_, œsophagus; _lbr_, labrum; _cl_, clypeus. ] In the Locustidæ (Anabrus, Fig. 71) the tongue (hypopharynx) is a broad, somewhat flattened lobe arising from the upper part of the base of the mentum and behind the palpifer. This lobe is cavernous underneath, the hollow being the salivary receptacle (_sr_); the latter is situated over the opening of the salivary duct, which is placed between the base of both the hypopharynx and the labium. The salivary fluid apparently has to pass up and around on each side of the hypopharynx in order to mix with the food. These relations in the Orthoptera are also the same in the Perlidæ, where the hypopharynx is well developed, forming an unusually large tongue-like mass, nearly filling the buccal cavity. [Illustration: FIG. 72.—Lingua of a May-fly, _Heptagenia longicauda_, ×16: _m_, central; _l_, lateral pieces.—After Vayssière from Sharp. ]