156 ANATOMY OF VERTEBRATES. 



from the angle to the symphysis of the lower jaw. The single 

 ducts of each gland unite just before their termination, which is 

 a simple orifice at the apex of the mouth. 



Besides the preceding, which may be considered as the true 

 salivary glands, there are numerous accessory follicles in different 

 parts of the oral apparatus of Birds. In the Waterhen ( Galli- 

 nula chlorojms) there is a series of coecal glandular tubes along 

 each side of the tongue : similar elongated follicles are situated 

 along the margin of the lower jaw, resembling in their parallel 

 pectinated disposition the branchiae of Fishes. In the Goose the 

 corresponding follicles are longer and wider, and are situated near 

 the sides of the tongue. In the Kaven these mucous follicles are 

 narrower but longer. The glandular structures supplying the 

 mouth in Birds may be summed up under the following heads : 

 ' folliculi linguales,' ' glanduloe sublinguales,' ^ glandule submaxil- 

 lares ' {Pici, Raptores, Rasores, Aptenodytes), ^ glandulje anguli 

 oris ' (Swan, Cantores, Diurnal Raptores) ; * folHculi preglottidei ; ' 

 ^ folliculi post-nasales,' i.e., opening behind the posterior nostrils ; 

 ' amygdalae,' or close-set groups of follicles, in two rows, opening 

 behind the eustachian outlet. 



§ 148. Alimentary Canal. — The food, after being imbued with 

 the secretion of the preceding glands, is poised upon the tongue and 

 swallowed, partly by means of the pressure of the tongue against 

 the palate, partly by a sudden upward jerk of the head. The pos- 

 terior apertures of the nostrils being generally in the form of narrow 

 fissures are undefended by a soft palate or uvula; and the laryngeal 

 aperture, which is of a similar form, is in like manner unprovided 

 mth an epiglottis, but is defended by the retroverted papillae at the 

 base of the tongue. In many Birds, indeed, as the Albatross and 

 Coot, there is a small cartilage in the usual place of an epiglottis, 

 but insufficient to cover more than a very small part of the laryn- 

 geal aperture.^ The surface of the mouth is rarely smooth above, 

 commonly provided with retroverted papillae : similar mechanical 

 helps to the right course of the food occur at or near the fauces, 

 in addition to those already noted on the tongue. The width of 

 the mouth in Caprimulgus, and the length and depth due to the 

 mandibular pouch in the Pelican, are remarkable. The extensi- 

 bility of the membrane between the rami of the lower jaw admits 

 of its formation into a bag, fig. 68, a, wliich is calculated to con- 

 tain ten quarts of water, and serves as a receptacle for fishes, 

 making in that state a conspicuous appendage to the huge bill ; 



* Fur these structures in Birds, see xxxvir. p. 613. 



