There is likewise a small muscle derived from the middle part of the styloid bone, the fibres of which run backwards and inwards, so as to meet those of the muscle last men tioned.
Lastly, there are two other muscles, the fibres of which take a longitudinal direction. One of these, the pharyngeus proprius, arises from the tendinous middle line that extends from below the insertion of the stylo-pha ryngei, and is prolonged downwards along the posterior and lateral walls of the oesophagus : the other, the aryteno-pharyngeus is a small muscular band proceeding from the back part of each arytenoid cartilage, and running down the front of the (esophagus towards the sto mach.
Stonzach. — In all the Solipeda the stomach is simple, and presents little remarkable in its shape. The oesophagus (fig. 510. b) is in serted at a very. acute angle into its smaller cur vature, which is, as it.were, folded upon itself. The cardiac cul.de-sac (c) is very capacious, and is lined throughout internally with a thick cuticular layer continuous with the lining of' the (esophagus, and extends nearly as far as the middle of the stomachal cavity, where it terminates abruptly by a prominent indented edge, the interior of the pyloric half of the viscus (a, d) presenting the usual villous mu cous surface. The muscular coat of the stornach consists of several superimposed layers of fibres that cross each other in differ ent directions, some of them being apparently derivations from the muscular bands of the (esophagus ; and it is doubtless the contrac tions of these muscular bands, in conjunction with the obliquity of the entrance of the oeso phagus, that renders the act of vomiting itn possible in these animals.
The alimentary canal in the Solipeds is short in comparison with that of the Rumi nants and some other herbivorous quadru peds ; but this want of length is perhaps more than made up for by the enormous capacity of the large intestine, which, on first opening the body of one of these animals, seems of itself to occupy the whole of the abdominal cavity.
Commencing from the pylorus, the duo denum (fig.510.f.) is found to be considerably dilated ; but its diameter soon contracts, and the rest of the tract of the small intestines is of pretty equable dimensions throughout, or if it presents constrictions here and there, they disappear when the gut is distended with air. The iliac portion of the small intestine (fig. 511. d) terminates in a crecum of enor mous bulk (fig. 511. a, b, c, e,f), which is separated from the commencement of the colon by a deep constriction (g): the colon itself is throughout its entire extent propor tionatel.y voluminous, commencing in the right flank : its ample folds (fig. 512. a, b) mount upwards as far as the diaphragm, whence they descend again, forming a viscus of vast capa city as far as the left iliac region, where, be coming gradually contracted in its dimensions, it terminates in the rectum. The ascending portion of the colon (a, 6) is separated from the descending part (c, d) by a constriction ; and the latter forms a third remarkable dila tation before it ends in the rectum. The
whole colon is puckered up into huge sacculi by three longitudinal muscular bands, which terminate where the rectum begins, the named division of the alimentary canal senting only a few pouches of comparatively small size, in which the fmces become moulded into balls preparatory to their expulsion. When in a state of moderate thstension, the small intestines of an ordinary size are found to measure about fifty-six feet in length from the pylorus to the cwcum, with a circumference varying according to the state of contraction of the bowel from two inches and a half to six inches. The maim is about two feet and a half long, and about two feet in circumfer ence at its broadest part ; but towards its blind termination it assumes a conical form, and terminates in a point (fig. 511. b). Above the ileo-cweal junction, the intestine forms a cul-de-sac (fig. 511.0, which is bent upon itself so as almost to resemble a second cwcum separated from the rest of the colon by a deep contraction, and there is, moreover, sometimes a third globular cavity, situated as shewn in Jig. 511.f : but this is not constantly present.
The enormous colon (fi,g. 512. a, b, c, d), which seems of itself to occupy the whole abdominal cavity, is divided into two por tions: — the first (a, b) is about 2 feet 3 inches long, and, at least, two feet in circumference ; the second portion (c, d) is of nearly the same dimensions ; but towards its termination, its circumference diminishes to 10 inches, and the continuation of the bowel retains that size for the length of a couple of feet, when it again enlarges to a cir cumference of 2 feet 4 inches before its ter mination in the rectum.
The entire length of the colon and rectum taken together is 21 feet, which, added to the length of the small intestines, gives a total length of 77 feet for the intestinal canal, ex clusive of the ewe:1m.
Liver. — This viscus in the horse is divided pretty equally between the left and the right sides of the body. It is divided into four lobes, measures about a foot and a half in its greatest diameter, and weighs between four and five pounds. There is no gall-bladder ; but the hepatic duet is extremely capacious, and evidently forms a receptacle for the biliary secretion.
Spleen. — The spleen of the horse has the shape of an elongated triangle, situated, ob liquely, upon the /eft side of the stomach ; its base pointing upwards and backwards, and its apex downwards and forwards; it is about 9 inches long, 4 inches broad at its widest part, and three-quarters of an inch in thick ness. Its weight is about twelve ounces.
The pancreas is of an irregular shape, ap pearing to be made up of three branches— the shortest of which terminates at the duodenum ; of the other two, one extends beneath the right, and the other reaches as far as the left kidney : these three branches form, by their union, a flattened mass, about half an inch in thickness, which may be called the body of the pancreas. There is nothing remarkable in the arrangement of its excretory duct.