352

width to near the pyloric end, c, which is too short to be bent. The duodenum, d, d, makes a large curve, and is a loose intestine, with a meso-duodenum which becomes shorter as it approaches the spine at the lower end of the curve: it is continued into the jejunum before crossing the spine. The biliary and pancreatic ducts, d, terminate about an inch from the pylorus. The length of the small intestines is 3 feet 2 inches, with a general circumference of one inch. The cæcum, fig. 352, c, is an inch in length, rather contracted at the neck, with an obtuse blind end: this is occupied by a patch of agminate follicles: a larger patch is at the end of the ileum, ib. a: the ileo-colic orifice and valve, b, are circular. The colon, d, is continued almost straight to the vent, e: the length of the large intestine was but 6 inches.

The Musteline, Subursine and Ursine Carnivora are, as a rule, devoid of cæcum. In the Martin (Mustela martes) the intestinal canal is three and a half times the length of the body. In the Otter the great and small curves of the stomach appear angular through the abruptness of the bend of the pyloric upon the cardiac part. The intestinal canal is relatively longer in Enhydra than in Lutra. In the Racoon the beginning of the colon is indicated by a slight enlargement and circular fold of the lining membrane, not produced so as to form a valve. In a Benturong (Ictides) I found a cæcal projection of half an inch in length at the beginning of a large intestine two feet in length: the small intestines were seven feet long; the length of the animal, exclusive of tail, was two feet. The stomach of Ailurus is subglobular, with terminal orifices; the narrow termination of the pyloric part has a thick mucous membrane. In the Bear there is a more marked blind sac at the left end; both muscular and mucous coats are thick. The villi of the small intestine are longer and coarser than in the Lion. In Urside the entire intestines are about twelve times the length of the body; in Felida from three to four times; in Viverride from four to six times: the longest in this family being in the frugivorous Palm-cats (Paradoxurus.)

In the common Seal (Phoca vitulina, L.) the oesophagus opens

widely into the left end of the stomach, leaving no blind sac there the pyloric end is bent acutely on the rest of the cavity : the pylorus is very small and is defended above by a valvular prominence, giving the opening a crescentic form; the diameter of the pylorus is an inch, while that of the cardia is 1 inch. The duodenum descends abruptly from the pylorus, and is connected by a continuation of peritoneum with the pyloric end of the stomach. It is contracted at its origin, but soon dilates, and a sacculus is formed between its muscular and mucous coats for the reception of the biliary and pancreatic secretions, which afterwards are conducted through a narrow passage into the intestine. Having descended as far as the right kidney, the duodenum turns to the left in the usual manner, but has a complete investment of peritoneum through its whole course: at the left side of the abdomen it carries forward this process of peritoneum, which forms the mesentery in the usual manner. The small intestines do not exceed 1 inch in circumference, but their deficiency in this part of their dimension is compensated by their great length. The large intestines commence by a short round cæcum, which, in two instances, was situated close to the pyloric end of the stomach: the greatest circumference of the colon was 4 inches. The Walrus has a similar cæcum. The interior of the stomach is smooth and without ruga; the intestines have the same character. In a Seal measuring 3 feet from the snout to the end of the hind flippers, the small intestines were 40 feet long, the large intestines 2 feet, with a cæcum of nearly one inch in length. The agminate glands run in long narrow strips.

§ 332. Alimentary canal of Bruta.-After exceptional instances in the Marsupial (Macropus) and Quadrumanous (Semnopithecus) orders, we now begin to find complex conditions of the gastric organ to predominate; the main characteristic of which in the present order is, that, when a laminate epithelium covers the lining membrane so thickly as to be comparable with cuticle, its most constant position is at the pyloric division of the stomach. There are, however, gradations, and the Armadillos retain most of the preceding more simple conditions of the alimentary tube. In Dasypus peba' the œsophagus, after the course of an inch in the abdomen, terminates in a stomach of a subglobular form about 11⁄2 inch from the left end: its epithelial lining ends at the cardia. The lining membrane of the stomach is villous, becoming smoother toward the pylorus; to that part a few longitudinal rugæ at the

1 CXXVII". P. 142.

middle of the cavity converge. The muscular coat is thin at the wide cardiac end, but attains a thickness of 2 lines near the pylorus, and here on each side there is a tendinous spot externally. A semilunar ridge defines the lower part of the pylorus; from the upper part depends a protuberance: this valvular structure resembles that in the Seal. Beyond the pylorus is a well-marked zone of racemose glands. In Dasypus 6-cinctus I found a greater proportion of the stomach to the left of the cardia: the other characters were repeated. The duodenum is dilated at its commencement and is suspended on a fold of peritoneum which becomes narrower as the gut descends: after crossing the spine the fold again expands to form the mesentery of the rest of the intestine. After a length of from 12 to 18 feet the gut suddenly expands, and here, in D. peba, the small intestine seems to enter, forming a narrow circular fold within, the larger intestine. The former are smooth internally, the latter shows a few longitudinal rugæ. In Dasypus 6-cinctus the large intestine expands into a pair of short, wide pouches, one on each side the insertion of the ileum. The terminal orifice of the ileum is a slit with tumid margins on the middle of the ridge between the two cæca. The length of the intestinal canal is 10 feet.'

In Orycteropus the lining membrane of the oesophagus is smooth: the tube terminates at the middle of the lesser curvature of the stomach the lining membrane of the large cardiac sac is disposed in coarse reticulate folds, which become longitudinal toward the pyloric end this is pyriform, with a muscular coat increasing to a thickness of 8 lines: the mucous coat showing strong rugæ, with an epithelium. The small intestines are of unwonted length in the present genus, about 37 feet: the lining membrane is without folds, but is beset with long and fine villi, and shows five or six elliptic patches of agminate glands in the ileum. The cæcum is between 4 and 5 inches in length; the colon about 8 feet long, and about 4 inches in circumference at the commencement.2

In the Pangolins (Manis) the distinction between the cardiac and pyloric portions of the stomach is still more marked the latter has acquired a greater accession of muscular fibres, and their tendinous centres are externally more conspicuous: the structure is made the more gizzard-like by its thick papillose cuticular lining. At the middle of the great curvature is a mass of complex glandular follicles, the ducts of which intercommunicate and terminate by a common orifice in the cavity of the stomach. The valvular protuberance above the pylorus is large. ' cxxvm". p. 155. CXLVII". p. 182, No. 590 c.

2 CXLIX". p. 16.

There is no cæcum. In the great Ant-eater (Myrmecophaga jubata) the stomach, fig. 353, presents a spherical form, of about 8 inches diameter, with a smaller subglobular appendage, as it seems, ib. h, h, of about 3 inches diameter, intervening between the main cavity, c, c, and the intestine, d. The oesophagus, a, terminates near the middle

353

very numerous

of the upper surface of the main, or cardiac, portion. On the middle of both the anterior and posterior surfaces of the stomach is a sheet of tendon, which extends from the large to the small division of the organ, expanding upon both divisions, but acquiring upon the latter its greatest thickness and whitest colour. The cardiac cavity, c, c, has a vascular secreting surface, the lining membrane being disposed in small wavy ruga: the larger and apparently more permanent folds converge toward the aperture, f, of the pyloric cavity. The cardiac orifice has the form of a narrow, slightly bent crescentic slit. situated about 3 inches from the similarly shaped aperture of communication between the cardiac and the pyloric cavities: but the margin of this latter aperture is indented, as it were, by the ends of the converging folds of the lining membrane, which are continued into the pyloric cavity. The pyloric division is remarkable for the thickness of its muscular tunic and the density of its epithelial lining, which convert it into a veritable gizzard. The muscular coat, ib. h, h, varies from 1 inch to an inch in thickness; at the middle of the cavity it is separated from the lining membrane by an unusual accumulation of the elastic submucous areolar tissue, i, which is most abundant in the upper wall of the cavity. A very small proportion only of food can enter at one time into this cavity, to be subjected to the triturating force of its parietes, operating, with the aid of swallowed particles of sand, in the comminution of the unmasticated or imperfectly masticated Termites. The area of the pyloric cavity, as exposed

It is

by the vertical longitudinal section in fig. 352, appears a mere linear, slightly sinuous, tract, with a dilatation near the pylorus, due to the valvular protuberance of the upper wall projecting toward that aperture. But, when the pyloric cavity is bisected transversely, its area presents a crescentic figure, owing to the protuberance formed by the thicker muscular tunic, h, and the more abundant submucous elastic tissue, i, in the upper parietes. The lower longitudinal plicæ, which commence on the cardiac side of the intercommunicating aperture, give a longitudinally ridged character to the inner surface of the cavity.

This character is changed near the pylorus for a reticular rugosity the pylorus, when viewed from the duodenal side, presents a crescentic form, with the horns of the crescent directed upward. The lining membrane of the duodenum soon becomes smooth. This intestine is suspended on a broad fold of peritoneum, and is continued into the jejunum without being tied by a contraction of the mesentery to the vertebral bodies. The ileum dilates rapidly into the colon which commences without a cæcal projection. The greatest circumference of the duodenum is 24 inches: the calibre of the intestinal canal gradually contracts to a circumference of 1 inch 9 lines at the jejunum, and recovers a circumference of 3 inches near the end of the ileum. The colon, within 3 inches of the ileum, has a circumference of 9 inches; and has decreased to a circumference of 6 inches, where it forms the rectum, about 9 inches from the anus.

The inner surface of the duodenum and jejunum is smooth, offering no villi to the naked eye. A few short and narrow longitudinal folds of the lining membrane, not parallel to but following one another, begin to appear in the ileum: these are succeeded by one or two longer longitudinal folds, which are soon followed by one extending continuously throughout the rest of the ileum, along the side of the gut opposite the attachment of the mesentery this fold is from 2 to 3 lines in breadth, is narrowest where the canal has been most distended, but is not obliterated by the utmost dilatation of the gut: it is a permanent single longitudinal production of the vascular lining membrane, and forms the chief characteristic of the lower half of the small intestines in the Myrmecophaga jubata. In this part of the canal there are patches of glandulæ agminatæ from 1 to 2 inches long, and with intervals of about 1 foot. The transition of the ileum into the colon is effected by a rapid increase of diameter, viz. from 1 inch to 2 inches; by a slight thickening of the muscular coat; by the appearance of a few transverse ridges or very low