In the Koala the under surface of the liver (fig. 130) is singularly sculptured and subdi vided into thirty or forty lobules; this condition is presented in a minor degree in the liver of the Ursine Dasyure.
In a long-tailed Dasyure, which weighed 3 lbs. 8} oz., the liver weighed 31 oz. avoir dupoise.
The gall-bladder is present in all the Marsu pials, and is generally of large size and loosely lodged in a deep cleft of the cystic lobe. In the Opossum it generally perforates that lobe, and the fundus appears at a round opening on the convex surface of the liver. The coats of the ductus choledochus are thickened towards its termination, and become the seat of nu merous mucous cysts which open into the in terior of the duct.
In the Phalangers the terminal half-inch of the ductus choledochus is similarly enlarged and glandular. The biliary and pancreatic ducts generally unite together before perforating the duodenum. In the Virginian Opossum, the long-nosed Bandicoot, and the long-tailed Dasyure they pour their secretions into the gut an inch from the pylorus. In the great Kan. garoo the glandular ductus choledochus is joined by the pancreatic duct, and terminates in the duodenum five inches from the pylorus.
The pancreas extends as usual from the duodenum to the spleen, be hind the stomach; it is characterized by a pro cess sent off at right angles, or nearly so, to the main lobe at or near its left extremity. I have observed other small and thin processes branching out into the duodenal mesentery in a Phalanger; and similar but still more nu merous processes, so as to give the organ a dendritic appearance in the Kangaroo; but the first-named process is constant.
The spleen.—It is interesting to observe that the spleen corresponds in this triangular or T shaped figure with the .pancreas. In the great Kangaroo ( Marropus major) I found the main body of the spleen ten inches long, and the rectangular process six'inches ; both parts were narrow and thin.
Absorbents.—The lacteal absorbents form, in the Dasyurus viverrinus, two thin, subelongate, dark-coloured mesenteric glands: one of these is situated near the pylorus, at the end of the pancreas. The plexiform cysterna chyli is si
tuated in the Kangaroo ( Illacropus Parryi was the species from which the following descrip tion is taken) upon the crura of the diaphragm, and extends upon the right side above the dia phragm into the thorax. Two thoracic ducts are continued from the cysterna, one the left, the other along the right side of the bodies of the dorsal vertebrae. The right duct crosses the seventh vertebra and joins the left, which again divides and reunites, forming a slight plexus, before finally terminating at the confluence of the left subclavian and jugular veins. The double thoracic duct in the Kangaroo was first noticed by Dr. Hodgkin; it is interesting, on account of its resemblance to the characteristic condition of the great nutrient conduit in the Bird and Crocodile ; in these, however, each division terminates in the vena innominata of its own side, which was not the case in the Kangaroo above described.
Blood—From the characteristic elliptical form of the blood-discs of Birds and Reptiles, and the rare occurrence of that form, as in the exceptional case of the Camel tribe, among the placental Mammalia, the examination of these particles of the circulating fluid in the Marsu pial genera was attended with more than ordi nary interest, and the results, derived from a comparison of species belonging to all the lead ing groups, show that the different tribes of Marsupial animals correspond with the analo gous placental Mammalia both in the circular or subcircular contour of the blood-discs, and very nearly also in their size.* Dasyurus viverrinus.—The blood-discs of this small carnivorous Marsupial were sensibly larger than those of the analogous placental 11-lammalia, as the Cat. The ordinary or un broken discs had their margin rounded off. The number of the granulated discs was con siderable; many of them presented a well defined margin, notched like a cog-wheel. The average diameter obtained by me was of an inch.