ABDOMINAL VISCERA OF THE HORSE. 21 
The size of the rectum is much the same as the single colon. 
It is puckered in its anterior part by two longitudinal bands; 
and the sacculi, resulting therefrom, determine the shape of the 
faecal matters. 
The rectum is superiorly related to the spine, whilst inferiorly 
it comes in contact with the bladder, bulbous portions of the vasa 
deferentia, vesiculae seminales, and prostate. 
‘The structure of the large intestine does not vary essentially 
from that of the small, as it possesses the four coats, i. e. peri¬ 
toneal, muscular, cellular, and internal mucous. 
The peritoneal tunic forms an entire covering to the large 
intestine, with the exception of the superior surface of the trans¬ 
verse colon—which is in contact with the pancreas—and the ter¬ 
minating portion of the rectum. The bands by which it unites 
the intestine to other parts have been already described. In 
addition to the peritoneum forming an entire covering to the 
gut, at the attached margin of the flexures of the colon it con¬ 
stitutes folds loaded with fat, varying in width in different parts, 
and clustered so as to have deserved the name of appendices 
epiploicse. 
The muscular coat of the large intestine is differently de¬ 
veloped in various parts. Its fibres are of the plain variety, 
and arranged in two orders. The outer longitudinal set is 
scanty in some parts, but in others forms the longitudinal bands 
above alluded to. These are shorter than the actual length of 
the gut itself, so as effectually to pucker it. The number of 
longitudinal bands varies from one to four in the various parts 
of the gut, and the shape and breadth of the latter is not every¬ 
where the same. The longitudinal fibres are abundant in the 
rectum, but they only form bands in the anterior two-thirds, 
as posteriorly to this they uniformly surround the gut. The 
inner layer of fibres encircles the whole of the gut, being 
thickest towards the apex of the caecum, as well as in the 
single colon and rectum : at the end of the latter the internal 
sphincter ani is formed by an accumulation of the circular 
fibres. The circular fibres of the colon are engaged in forming 
the ileo-colic valve, hereafter to be described. 
The cellular coat of the large intestine resembles that of the 
small, only not so abundant, except at the terminating portion 
of the rectum, where it is much more developed. 
The mucous lining of the large intestine is continuous an¬ 
teriorly with that of the ileum, posteriorly with the common 
integument. It is thin, more. or less coated with mucus, 
scantier in glands than the one of the small intestine, but the 
orifices of the Lieberkuchnian crypts are more apparent, owing 
to the surface here being destitute of villi. Saccular recesses, 
