14 T'ransactions.— Miscellaneous, 
the Diprotodon, the Zygomaturus, and Nototherium, in the marshy savan- 
nahs of Australia, but as these became drained in the course of the gradual 
elevation of the land and converted into arid plains, swept by sirocco-like 
winds, the sueculent vegetation upon which they lived failed, we may 
presume, and remaining represented by related animals of comparatively 
pigmy size, they disappeared utterly as the Megatherium, the Megalonyx, 
and Mylodon of South America, which likewise leaving small analogues 
behind, passed from the face of the earth under the influence of some such 
cause, or destroyed by the irresistible attacks of internal parasites, (as we 
see hosts of domestie animals now throughout extensive districts of 
Australia, unable to resist the enemies which had proved less dangerous to 
the indigenous marsupials, from whom they were derived), or of swarms of 
pestiferous insects, such as the tsetse fly of Africa, or the calf- and foal- 
murdering one of Patagonia.* 
It will not be proposed that any change of temperature destroyed the 
aboriginal horse of North and South America. Herds of these animals 
roamed in comparatively recent times from the cold north to the Patagonian 
plains, and their contemporaries flourish there still. Whatever was the 
cause of their extinction, it had ceased to act when the Spaniards conquered 
Mexico, for the new equine race introduced by them has multiplied 
rapidly, and continues to flourish equally well in a feral as in a domestic 
state. When the plague or the cholera take their tens of thousands of men, 
the lower animals remain generally unscathed, and vice-versa. 
The parasitical worms which are so fatal to the flocks of the Australian 
sheep-farmer abound in the kangaroo and wallabi, and the former, if left to 
themselves, would ere long become extinct, destroyed in some districts by 
the parasites, in others starved out by the increasing hordes of hardy 
marsupials. The increase of this inferior order of animals as it stands in 
the derivative pedigree has been immense since the balance was destroyed 
by the extinction of the dingo, and since the aboriginal men have so much 
decreased in numbers. Thirty thousand kangaroos of large and smaller 
- tribes have lately been killed on a single settler’s run without making any 
observable diminution in their strength, and until some epidemic arises 
amongst them, their singularly rapid increase will tax the efforts of the 
white man to check in these thinly peopled regions. If these marsupials are 
so inferior a grade of animals, they are at all events admirably adapted for 
the situation they now occupy; so peculiarly well adapted to it that after 
* An interesting ipee f of this kind i : now being observed over large cat un 
in the interior of New South Wales, which, if it continued, would lead in time to the 
a of ae eattle ue rt Saget pi piebald horses in the herds, oa being 
attacked by se caused by a black Aphis covering the pastures, producing fatal 
effects upon an young di and even many grown ones, whilst those whose coats are 
. otf dark colours do not suffer 
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