600 



AVES BIRDS. 



this living mill, and retain the material to be ground within the in- 

 fluence of the crushers until it is properly prepared, when other 

 fibres, acting the part of a pylorus, allow it pass on into the duode- 

 num (e). 



(668.) The intestinal canal of Birds is, as in other classes, very 

 variable in its relative length as compared with that of the body: its 

 calibre is pretty equal throughout, and the division into large and 

 small intestines can scarcely be said to exist. Commencing from the 

 pylorus, the duodenum (Jig- 273, rf, A) is always found to make a long 

 and very characteristic loop, embracing the lobes of the pancreas 

 (e, e), and then, after sundry convolutions, the intestine is con- 

 tinued to its termination in the cloaca. The division between 

 the large and small intestines is indicated by the presence of one, 

 or more generally two, csecal appendages, which communicate with 

 the cavity of the gut at no great distance from its cloacal extremity. 



(669.) In Birds, the auxiliary secretions subservient to the 

 digestive process are the salivary, the gastric, the hepatic, and 

 the pancreatic. 



The salivary apparatus varies much in structure and disposition in 

 different tribes. In its simplest form it consists of distinct secerning 

 follicles, placed immediately beneath the mucous membrane of the 

 mouth, into which the secretion is poured by numerous orifices. 

 In the Gallinaceous Birds the glands assume a conglomerate cha- 

 racter. In the Turkey there are two pairs :* the first pair forms 

 a cone, having its apex directed towards the extremity of the 

 beak ; and the two glands of the opposite sides touch each other 

 along the mesial line through almost their entire length, filling up 

 anteriorly the angle of the lower jaw. These glands are situated 

 immediately beneath the skin, but in front they touch the mucous 

 membrane of the rnouth ; and their secretion is poured into the 

 buccal cavity by several orifices. The second pair of glands is 

 smaller, of an elongated form, and is placed above the posterior 

 third of the former, this is immediately in contact with the 

 mucous lining of the mouth. 



In the Woodpeckers the glands that secrete the fluid whereby 

 the tongue is lubricated are of very considerable size. They pass 

 further back than the angle of the lower jaw, extending even to 

 beneath the occiput ; and their secretion, which is viscid and 

 tenacious, enters the mouth by a single orifice situated under the 

 point of the tongue. 



* Cuvier, Leyons d'Anat. Comp. torn. iii. p. 221. 



