THE ANATOMY OF BIRDS. — SPLANCHNOLOGY. 
211 
processes of mucous membrane, knobbed or acute, 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). 
The floor in some cases forms a pouch, which, as in the case of the pelican, is of great extent 
and susceptible of enormous dilatation (fig. 501). 
The handler of the mouth, or lingual organ, is the tongue, which answers the same pur- 
pose 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 filling 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 affect 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 'Hongue " appears as a 
lumbriciform (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 (Rham- 
phastidce) 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 
upon 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 horny 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. 167); the free lingual part 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, ^ and 8). 
The OEsophagus. — After comminution, if any, by the beak, and insalivation in the 
mouth, food passes directly through the pharynx into the oesophagus or gullet, — a musculo- 
membranous tube connecting mouth with stomach (fig. 101, i, g, h, i). This is composed (besides 
its mucous membrane) of circularly disposed constrictor fibres, and longitudinal contractor fibres, 
of Myamoeba, of the pale, smooth species (M. Icevis). 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 contractions, permanent or temporary, aside from the mere distension caused by the pas- 
sage of food. When the floor of the mouth is wide and loose, the gullet partakes of the same 
character above ; the extreme case is afforded by the pelicans, especially P. fuscus. But the 
