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the Aquatic Mammals. And this great group, containing so 
many orders, is named Monadelphia. 
The other great groups consist of all the marsupials, and no 
others. It consists, therefore, of the single order, Marsupi- 
alia , and is called Didelphia. 
Another group of mammals is made up of two genera only — 
the Duck-billed Platypus or Ornithorhyncus and the Echidna , 
two most interesting forms but which cannot be further 
noticed here. They form, by themselves, a theme amply suffi- 
cient for an article, or even half-a-dozen articles. 
As to' its zoological relations, then, we may say that the 
kangaroo is a peculiarly modified form of a most varied 
order of mammals (the Marsupials), which differ from all 
ordinary beasts (and at the same time differ from man) by 
very important anatomical and physiological characters , the 
sign of the presence of which is the coexistence of marsupicd 
bones with an inflected angle of the lower jaw. 
We may now proceed to the next subject of enquiry, and 
consider the space relations (that is, the geographical distribu- 
tion) of the kangaroo, its family, and order. I have already 
incidentally mentioned, some countries where marsupials are 
found, but all of these were more or less remote. To find living, 
in a state of nature, any member of the kangaroo’s order, we 
must at least cross the Atlantic. 
When America was discovered by the Spaniards, amongst 
the animals found there, and afterwards brought over to 
Europe, were opossums , properly so called — marsupials, of the 
family Didelphidce , which extend over the American continent, 
from the United States to the far South. These creatures were 
the first to make known to Europeans* that habit of sheltering 
the young in a pouch which exists in the kangaroo, and which 
habit has given the name Marsupialia to the whole order. 
But though this habit was duly noted, it is not strange that 
(being the only pouched forms then known) the value of 
the peculiarity should have been under-estimated. It is not 
strange that they should have been regarded as merely a new 
kind of ordinary flesh-eating beasts, since in the more obvious 
characters of teeth and general form they largely resembled 
such beasts. Accordingly even the great Cuvier, in the first 
edition of his “ Regne Animal,” made them a mere subdivision 
of his great order of flesh-eating mammals. 
But to find any other member of the kangaroo’s order 
* The following are some amongst the earlier notices of these animals : — 
u Historie d’un Voyage fait en la terre du Brasil,” par Jean de Lery ; Paris, 
1578, p. 156. Ilernande’s “Hist. Mex.,” p. 330, 1626. “Historie Naturelle 
des Antilles; ” Rotterdam, 1658. “Anatomy of an Opossum,” Tyson, Phil. 
Trans., 1698. 
