Ch. X.] LAW OF GEOGRAPHICAL RELATIONSHIP. 129 



land-shells formerly their contemporaries still continue to exist 

 in the same countries. As we may feel assured that these minute 

 quadrupeds could never have been extirpated by man, especially in a 

 country so thinly peopled as Brazil, so we may conclude that all the 

 species, small and great, have been annihilated one after the other, in 

 the course of indefinite ages, by those changes of circumstances in 

 the organic and inorganic world which are always in progress, and are 

 capable in the course of time of greatly modifying the physical geogra- 

 phy, climate, and all other conditions on which the continuance upon 

 the earth of any living being must depend.* 



The law of geographical relationship above alluded to, between the 

 living vertebrata of every great zoological providence and the fossils 

 of the period immediately antecedent, even where the fossil species 

 are extinct, is by no means confined to the mammalia. JNTew Zea- 

 land, when first examined by Europeans, was found to contain no in- 

 digenous land quadrupeds, no kangaroos, or opossums, like Australia ; 

 but a wingless bird abounded there, the smallest living representative 

 of the ostrich family, called the Kiwi by the natives (Apteryx). In 

 the fossils of the Post-pliocene period in this same island, there is the 

 like absence of kangaroos, opossums, wombats, and the rest ; but in 

 their place a prodigious number of well-preserved specimens of gigan- 

 tic birds of the struthious order, called by Owen Dinornis and 

 Palaptenjx, which are entombed in superficial deposits. These genera 

 comprehended many species, some of which were four, some seven, 

 others nine, and others eleven feet in height ! It seems doubtful 

 whether any contemporary mammalia shared the land with this popu- 

 lation of gigantic feathered bipeds. 



Mr. Darwin, when describing the recent and fossil mammalia of 

 South America, has dwelt much on the wonderful relationship of the 

 extinct to the living types in that part of the world, inferring from 

 such geographical phenomena that the existing species are all re- 

 lated to the extinct ones which preceded them by a bond of common 

 descent. 



The late able naturalist, Edward Forbes, had declared in 1846 his 

 conviction that, not only the great extinct deer, Cervus megaceros, but 

 also the mammoth, and other lost pachyderms and carnivora, lived in 

 Britain after the extreme cold of the glacial period had passed away.f 

 More recent observations by Mr. Prestwich and Dr. Falconer, on the 

 fossil contents of the drift and cave deposits of England, have confirmed 

 this opinion, and have also 1 proved that a larger number of the lost 

 species than Forbes probably suspected were posterior in date to the 

 submergence of central England beneath the waters of the glacial sea 

 — an event which will be spoken of in the twelfth chapter. Mr. 

 Prestwich has pointed out that there are some contortions of the 



* See Principles of Geology, chaps, xli. to xliv. 

 f Memoirs of Geol. Survey, pp. 394, 397. 



