_I._ A longitudinal section through a feather papilla showing a young feather. 1, The developing feather. 2, The horny sheath. 3, The epithelium. 4, Stratum corneum. 5, Stratum malpighi. 6, Corium. 7, Malpighian cell group of the follicle. ] _The Hard Palate._—The hard palate, palatum durum, forming the roof of the mouth has for its boundaries the beak anteriorly, the mandibular arches laterally, and the pharynx posteriorly. It has four or five transverse bars, projecting posteriorly from each of which is a row of filiform papillæ (Figs. 27 and 29). [Illustration: FIG. 30.—A section through the wall of the crop of a hen. 1, The outer muscular layer showing longitudinal fibers. 2, The inner muscular layer showing the sectioned ends of the bundles of muscle fibers. 3, Stratified squamous epithelium. 4, The outer surface or lumen of a fold. 5, The stroma, muscularis mucosa, and submucosa. ] The _beak_ (Fig. 4, No. 1) with little if any aid from the tongue, is the prehensile organ. =The Tongue= (Fig. 27, No. 3). _Location._—The tongue (lingua) of the fowl is situated in the floor of the mouth between the rami of the lower mandible, and is slung to the cranium by the cerato-branchial element of the os hyoideum (Fig. 18, No. 2). _Shape._—The tongue, is pointed in front and wide behind, shaped like an Indian arrow-head, and is supported by the bony and cartilaginous hyoid apparatus (Fig. 9, _A_). [Illustration: FIG. 31.—The visceral organs of the hen. 1, Tongue. 2, Larynx. 3, Glottis. 4, First portion of the esophagus. 5, Crop. 6, Second portion of the esophagus. 7, Proventriculus. 8, Duodenum. 9, Free or floating portion of the small intestine. 10, Mesentery supporting the free portion of the small intestine. 11, Cæca. 12, Rectum or large intestine. 13, Cloaca. 14, Anus. 15, Liver. 16, Gall-bladder. 17, Pancreas. 18, Gizzard. 19, Trachea. 20, Lungs. 21, Spleen. ] _Structure._—The free part of the tongue consists of two long tubes which are formed by the rolling in of the ventral sides of its horny coverings. The _dorsal plate_, which constitutes one-half of the horny sheath, does not form a part of the tubes, but ends in the region of the point of the entoglossum. The top surface is covered by a thick stratum corneum, giving it a rather horny surface. Glands occur in the posterior part of the tongue. While not so freely movable as in mammals, the tongues of birds are very flexible.