MARSUPIALIA. 
Fig. 130. 
Liver of the Koala. 
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.—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- 
VOL. IIT. 
305 
shaped figure with the pancreas. In the great 
Kangaroo ( Macropus major ) 1 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 ( Macropus 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 along the left, 
the other along the right side of the bodies of 
the dorsal vertebree. 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—¥rom the characteristic elliptical 
form of the blood-dises 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-dises of 
this small carnivorous Marsupial were sensibly 
larger than those of the analogous placental 
Mammalia, 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 z)),th of 
an inch, 
Dasyurus ursinus.—The average diameter of 
the blood-discs is 34: observed extremes of 
Size sh, and 74,,. 
Perameles lagotis—The blood of this Mar- 
supial, which was examined while recently 
drawn from the living animal, and under the 
same circumstances as that of the two species 
of Dasyure, presented a still greater number of 
the granulated blood-discs mixed with others 
of the ordinary form. The descriptions of such 
altered blood-dises not only by Hewson and 
Falconer, and in recent times by Professor 
* See Medical Gazette, November 13, 1839, and 
Mr. Gulliver’s observations, London and Edinb. 
Philos, Magazine, February, 1840. 
x 
