MARSUPIALIA. 



301 



The stomach of the Kangaroo may be re- 

 garded as consisting of a left, a middle, and a 

 right or pyloric division. The left extremity of 

 the stomach is bifid, and terminates in two 

 round cul-de-sacs. The sacculi of the stomach 

 are produced, like those of the colon, by three 

 narrow longitudinal bands of muscular fibres, 

 which gradually disappear, together with the 

 sacculi at the pyloric division. One of the 

 longitudinal bands rurs along the greater cur- 

 vature, at the line of attachment of the gastro- 

 colic omentum ; the others commence at the 

 base of the left terminal pouches, and run, one 

 along the anterior, the other along the posterior 

 side of the stomach : the interspace, between 

 these bands, forming the lesser curvature of 

 the stomach, is not sacculated. The largest of 

 the two terminal sacculi (d, Jig. 124) is lined 

 with an insulated patch of vascular mucous 

 membrane, which is continued for the extent 

 of five inches into the cardiac cavity ; the epi- 

 thelium is continued from the oesophagus in 

 one direction into the nearest and smallest sac- 

 culus, and extends in a sharp-pointed form for 

 a considerable distance in the opposite direction 

 into a series of sacculi in the middle compart- 

 ment of the stomach (c) : this epithelium is quite 

 smooth. The vascular mucous surface recom- 

 mences by a point at the great curvature, near 

 the beginning of the middle compartment, and 

 gradually expands until it forms the lining of 

 the whole inner surface of the right half of the 

 stomach. Three rows of clusters of mucous fol- 

 licles (g,g) are developed in the mucous mem- 

 brane of the pyloric half of the middle com- 

 partment; they are placed parallel with the lon- 

 gitudinal muscular bands : about fifteen patches 

 are situated along the greater curvature, and there 

 are nine in each of the anterior and posterior 

 rows. These glandular patches disappear alto- 

 gether in the pyloric compartment of thestomach, 

 where the lining membrane is thickened, and 

 finely corrugated; but immediately beyond the 

 pylorus there is a circular mucous gland three- 

 fourths of an inch broad : the non-sacculated 

 pyloric division of the stomach was five inches 

 in length. 



In the smaller species of Kangaroo the 

 stomach is less complicated than in the Macro- 

 pus major ; the number of sacculi is fewer: in 

 Macropus Parryi, Ben. the third longitudinal 

 band at the great curvature of the stomach is 

 almost obsolete : in the Brush-tailed or Rock 

 Kangaroo, ( Macropus penicillatus,) the cardiac 

 extremity terminates in a single sub-clavate cul- 

 de-sac. In all the species which I have exa- 

 mined the oesophagus terminates in the middle 

 division of the stomach, close to the produced 

 crescenticfold which separates it from the cardiac 

 compartment. In the great Kangaroo a second 

 slighter fold is continued from the right side of 

 the cardiac orifice parallel with the preceding, 

 and forming with it a canal, somewhat analogous 

 to that in the true ruminating stomachs, and 

 along which fluids, or solid food not requiring 

 previous preparation in the cardiac cavity, might 

 be conducted into the middle compartment. 



I have more than once observed the act of 

 rumination in the Kangaroos kept in the Viva- 



rium of the Zoological Society. It does not 

 take place while they are recumbent, but when 

 the animal is erect upon the tripod of the hind 

 legs and tail. The abdominal muscles are in 

 violent action for a few seconds, the head is 

 then a little depressed, and the cud is masti- 

 cated by a rapid rotatory motion of the jaws. This 

 act is by no means repeated in the Kangaroos 

 with the same frequency or regularity as in the 

 true Ruminants. A fact may, however, be 

 noticed as an additional analogy between them ; 

 balls of hair, cemented by mucus, adpressed 

 and arranged in the same direction, are occa- 

 sionally formed in the stomach, of which I 

 have met with two, of an oval shape, in the 

 Macropus Parryi. 



In the genus Hypsiprymnus the stomach is 

 as singularly complicated as in the Kangaroos, 

 and the complication is essentially the same in 

 both ; arising from the sacculation of the pa- 

 rietes of a very long canal by a partial dispo- 

 sition of shorter bands of longitudinal fibres ; 

 but in the Potoroos this sacculation is confined 

 to that part of the stomach which lies to the 

 left of the oesophagus, while the right division 

 of the cavity has the ordinary form and struc- 

 ture of the pyloric moiety of a simple stomach. 

 The left or cardiac division is enormously de- 

 veloped ; in relative proportion, indeed, it is 

 surpassed only by the true ruminant stomachs, 

 in which both the rumen and reticulum are 

 expansions of the corresponding or cardiac 

 moiety of the stomach. The relation of the 

 stomach of a Potoroo to that of a Kangaroo 

 may be concisely expressed by stating that the 

 termination of the oesophagus in the former is 

 removed from the commencement of the middle 

 sacculated compartment to its termination. 



When fluid is injected into the stomach of 

 a dead Potoroo, it distends first the pyloric 

 division; it is probably by a kind of anti- 

 peristaltic action that the aliment is propelled 

 into the long sacculated coecum to the left of 

 the oesophagus. 



The modifications of the epiploon, as an ap- 

 pendage to the stomach, may here be noticed. 

 In the Kangaroo it is of very moderate size, 

 being continued loosely from the stomach to 

 the transverse colon, but not extended beyond 

 that part. The posterior layer lies between the 

 stomach and the intestines, and affords a good 

 illustration of one of the uses of the epiploon, 

 as it evidently prevents these parts from inter- 

 fering with each other's motions. The anterior 

 layer generally contains more or less fat. In 

 the Petaurus the great omentum is continued 

 from the great curvature of the stomach, and 

 the commencement of the duodenum. In the 

 Phalangers it is of considerable extent, and 

 is usually loaded with fat. In the Opossums I 

 have found it generally devoid of fat, when 

 this substance has been accumulated in other 

 parts. In the Phascogales and Dasyures the 

 epiploon is of moderate size, and contains 

 little or no fat. 



Having seen that, with the exception of the 

 Potoroos and Kangaroos, the stomach is simple 

 in the Marsupialia, presenting only some addi- 

 tional mucous glands in the Koala and Worn- 



