14 'ririn^acliniix. — ^[isci'llaitcaKs, 



the DiprotoiTou, the Zygomaturus, and Nototherium, iu the marshy savan- 

 nahs of AustraUa, bixt as these became di-ainecl in the course of the gi-aclual 

 elevation of the land and converted into arid plains, swept by sirocco-hke 

 winds, the succulent 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 Megalonj'x, 

 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 domestic 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-vcrsu. 



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, wox;ld 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 iu 

 the derivative pedigi'ee 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 then- strength, and until some epidemic arises 

 amongst them, their singularly rapid increase will tax the efforts of the 

 white man to check iu 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 circumstance of this kind is now being observed over large districts 

 in the interior of New South Wales, which, if it continued, would lead in time to the 

 disappearance of white cattle and white-legged or piebald horses in the herds, sucli being 

 attacked by a disease caused by a black ,473 /(if covering the pastures, producing fatal 

 effects upon all young animals, and even many grown ones, whilst those whose coats are 

 of dark colours do not sutfer at all. 



