THE ANATOMY OF BIRDS. — SPLANCHNOLOGY. 217 



processes of mucous membrano, knobbed or acuto, may occur elsewhere in lines and patches. 

 The roof of the mouth is nearly all " hard palate," as already said; its soft floor is the mucous 

 membrane and skin between the jaws, with muscular or other intervening structures. The 

 principal flooring muscle is the mylo-hyoid ; the genio-hyoid ("fig. 101, i, d) is another, which 

 passes, like the first, from the mandibular to the hyoid bone; a third is the stylo-hyoid (e). 

 Tlie floor in some cases fonns a pouch, which, as in the case of the pelican, is of great extent 

 and susceptible of enormous dilatation (fig. 669). 



The handler of the mouth, or lingual organ, is the tongue, which answers the same pur- 

 ]">se as in other creatures: it is tactile, to some extent gustatory, sometimes prehensile, nearly 

 always manipulatory. In some birds, as the pelican and ibis, and also the kingfisher, it is 

 very sliglitly developed, — scarcely more than a pad at the bottom of the mouth, enjoying the 

 most limited motion or other function. In some birds, as the parrot and duck tribes, and also 

 the flamingo, the tongue is large, thick, and fleshy, quite filhng the mouth. In the first- 

 named of these, it is dexterously manipulatory ; the morsel of food is managed between the 

 tongue and upper beak ; the tactile certainly and perhaps the gustatory sense is highly devel- 

 oped ; and the fleshiness of the tongue may aflect that power of articulate speech for which 

 some parrots are justly noted. In the Lamellirostres just mentioned the tongue has lateral 

 processes corresponding to the denticulations of the beak, and the under surface is horny at the 

 end, like a human finger-nail. In the woodpeckers (figs. 73, 74) the tongue itself, (glosso-hyal 

 part of the hyoid) is reduced to a slight horny and spiny tip of the lingual apparatus; but other 

 parts of that mechanism are so extraordinarily developed that the " tongue " appears as a 

 lumhriciform (worm-like), spear-headed organ usually capable of great protrusion from the 

 mouth, and therefore acting as a prehensile instrument, being bedewed for that purpose with 

 tenacious saliva from the great salivary glands ; while it is actuated in protrusion and retraction 

 by specially developed muscles. In the snipe and many of the long slender-billed waders, the 

 tongue is similarly slender, but not protrusible. The long narrow tongue of the toucans {Illiam- 

 jjhastidff) is beset with slender processes, so that it seems feathery. The tongue of the hum- 

 ming-bird is very singular, — delicately thready, yet double-barrelled, — two tubes placed 

 side by side, serving as siphons to extract the nectar of flowers. These and other 

 interesting extremes aside, the ordinary style of a bird's tongue is flat, narrow, more or less 

 sagittate or lanceolate, and tipped or sheathed in horn, commonly with lateral backward pro- 

 cesses like the barbs of an arrow head, — the whole glossal structure upborne pretty distinctly 

 u{)on the end of the basihyal bone. (See fig. 101, where i, a, is such an ordinary tongue, and 

 2, a-f, is its whole skeleton.) Such homy tongues are commonly bifid at the extreme tip 

 or there variously lacerate, or laciniate, or thready, — and even the fleshy tongue of some 

 parrots, as the lories, is brushy at the end. The bony foundation of the tongue is the com- 

 posite hyoid bone, already often mentioned (see p. 173); the free lingual ])ait proper is based 

 upon the glosso-hyal and its terminal cartilage; the roots curve more or less extensively about 

 the base or more of the skull. The tongue is moved by some intrinsic muscles, as well as by 

 those extrinsic ones by which it is connected to the skull, jaw, and windpipe (fig. 101, i and 8). 



The CEsophagus. — After conuninution, if any, by the beak, and insalivation in the 

 mouth, food passes directly through the pharynx into the ffS0/)/io<7«s or gullet, — a musculo- 

 membranous tube connecting mouth with stomach (fig. 101, ', g, h, i). This is composed (besides 

 its mucous membrane) of circularly disposed constrictor fibres, and longitudinal contractor fibres, 

 of Myamceba, of the pale, smooth species (M. leevis). It has generally a pretty straight course, 

 but may be diverted to one side or the other ; and, in particular, is subject to various dilatations 

 and cf)ntractions. permanent or temporary, aside from the mere distensit>n caused by the pas- 

 sage of food. When the floor of the mouth is wide and loose, the gullet partakes of the same 

 tharacter above ; the extreme case is afforded by the pelicans, especially P. fusctis. But the 



