318 STRUCTURE OF THE SHEEP. 



conveyed by the tongue, is by the same organ carried to the 

 back of the mouth, and being softened by the saliva and 

 thereby mixed with atmospheric air, enters a flesliy bag 

 called the pharynx or gullet. 



This pharynx is lined by the same membrane as the 

 mouth, and is surrounded by, and, in fact, composed of vari- 

 ous muscles, which contracting force the food forwards into 

 a long tube called the oesophagus, which leads to the stomach. 

 The pharynx is situated inmiediately above the larynx or 

 cartilaginous box which forms the entrance to the windpipe, 

 and the food in entering the gullet passes over the entrance 

 to the larynx, which it is prevented from entering by a trian- 

 gular lid termed the epiglottis, which in the act of swallow- 

 ing shuts down on the larynx, but otherwise leaves it open 

 for the purpose of respiration. The food after leaving the 

 gullet enters the oesophagus, a very long tube lined internally 

 by a white insensible membrane, and externally by muscu- 

 lar coats, which, by contracting, force the food onwards to 

 the stomach. The oesophagus passes down the neck to- 

 wards its left side and somewhat above the windpipe, with 

 which it enters the chest between the two first ribs ; it then 

 takes an upward or ascending course through the cavity of 

 the chest over the base of the heart, passes the midriff or 

 diaphragm, and then descending soon afterwards reaches 

 the stomachs. On entering the chest it somewhat dimin- 

 ishes in size, but again expands in the abdomen. It does 

 not actually terminate in either of the stomachs, but in what 

 is called the oesophagean canal, which is about four inches 

 and a half in extent, and is formed above by a continuation 

 of the oesophagus, and below by a sort of muscular pillars 

 — duplications of the upper portions of the first and second 

 stomachs. Thus the oesophagean canal is a sort of lobby 

 or passage having entrances to the different stomachs, and 

 which, with the exception of the second and fourth, are the 

 only entrances these stomachs possess. By the annexed 

 cut it will be seen that the food duct commences at the en- 

 trance to the rumen, and for the space of three inches its 

 floor consists of muscular pillars or lips, formed by the up- 

 per part of the second stomach, the entrance to which is be- 

 tween these lips. The pillars then continue within the 

 cavity of the third stomach for the space of an inch and a 

 half to the entrance of the fourth stomach, the cavity of the 

 third being principally situated above, forming the roof of 



