EQUIDuE 399 



glands, the ducts of which open on the mucous membrane of the 

 upper lip. 



The stomach of the Horse is simple in its external form, with 

 a largely developed right ad de s«<\ and i.s a good deal curved 

 on itself, so that the cardiac and pyloric orifices are brought near 

 together. The antrum pyloricum is small and not very distinctly 

 marked off. The interior is divided by the character of the lining 

 membrane into two very distinct portions, right and left. Over 

 the latter the dense white smooth epithelial lining of the oesophagus 

 is continued, terminating abruptly by a raised crenellated border. 

 Over the right part (rather the larger portion) the mucous membrane 

 has a grayish-red colour and a velvety appearance, and contains very 

 numerous peptic glands, which are wanting in the cardiac portion. 

 The oesophageal orifice is very small, and is guarded by a strong 

 crescentic or rather horse-shoe-like band of muscular fibres, which is 

 supposed to be the cause of the difficulty of vomiting in the Horse. 

 The small intestine is of great length (80 to 90 feet), its mucous 

 membrane being covered with numerous fine villi. The caecum is 

 of conical form, about 2 feet long and nearly a foot in diameter ; 

 its walls are sacculated, especially near the base, having four longi- 

 tudinal fibrous bands ; and its capacity is about twice that of the 

 stomach. It lies with its base near the lower part of the abdomen, 

 and its apex directed towards the thorax. The colon is about one- 

 third the length of the small intestine, and very capacious in the 

 greater part of its course. As usual, it may be divided into an 

 ascending, transverse, and descending portion ; but the middle or 

 transverse portion is folded into a great loop, which descends as low 

 as the pubis ; so that the colon forms altogether four folds, generally 

 parallel to the long axis of the body. The descending colon is much 

 narrower than the rest, and not sacculated, and being considerably 

 longer than the distance it has to traverse, is thrown into numerous 

 folds. 



The liver (Fig. 166) is tolerably symmetrical in its general 

 arrangement, being divided nearly equally into segments by a well- 

 marked umbilical fissure. Each segment is again divided by lateral 

 fissures, which do not extend quite to the posterior border of the 

 organ ; of the central lobes thus cut off, the right is rather the larger, 

 and has two fissures in its free border subdividing it into lobules. 

 The extent of these varies, however, in different individuals, being 

 not usually so marked as in the figure, which is from a foetal 

 specimen. The two lateral lobes are subtriangular in form. The 

 Spigelian lobe is represented by a flat surface between the portal 

 fissure and the posterior border, not distinctly marked off from the 

 left lateral by a fissure of the ductus venosus, as this vessel is buried 

 deep in the hepatic substance, but the caudate lobe is distinct and 

 tongue-shaped, its free apex reaching nearly to the border of the 



