1834.] TYPES OF ORGANIZATION CONSTANT. Wwe 
present shells. I was at first much surprised how a Jarge quad- 
ruped could so lately have subsisted, in lat. 49°15’, on these 
wretched gravel plains with their stunted vegetation ; but the 
relationship of the Macrauchenia to the guanaco, now an inha- 
bitant of the most sterile parts, partly explains this difficulty. 
The relationship, though distant, between the Macrauchenia 
and the Guanaco, between the Toxodon ahd the Capybara,— 
the closer relationship between the many extinct Edentata and 
.the living sloths, ant-eaters, and armadillos, now so eminently 
characteristic of South American zoology,—and the still closer 
relationship between the fossil and living species of Ctenomys and 
Hydrocherus, are most interesting facts. This relationship is 
- shown wonderfully—as wonderfully as between the fossil and 
extinct Marsupial animals of Australia—by the great collection 
lately brought to Europe from the caves of Brazil by MM. Lund 
and Clausen. In this collection there are extinct species of all 
the thirty-two genera, excepting four, of the terrestrial quadru- 
peds now inhabiting the provinces in which the caves occur ; 
and the extinct species are much more numerous thari those now 
living: there are fossil ant-eaters, armadillos, tapirs, peccaries, 
guanacos, opossums, and numerous South American gnawers and 
monkeys, and other animals. This wonderful relationship in the 
same continent between the dead and the living, will, I do not 
doubt, hereafter throw more light on the appearance of organic 
beings on our earth, and their disappearance from it, than uny 
other class of facts. 
It is impossible to reflect on the changed state of the American 
continent without the deepest astonishment. Formerly it must 
have swarmed with great monsters: now we find mere pigmies, 
compared with the antecedent, allied races. If Buffon had known 
of the gigantic sloth and armadillo-like animals, and of the lost 
Pachydermata, he might have said with a greater semblance of 
truth that the creative force in America had lost its power, 
rather than that it had never possessed great vigour. The 
greater number, if not all, of these extinct quadrupeds lived at 
a late period, and were the contemporaries of most of the existe 
ing sea-shells. Since they lived, no very great change in the form 
of the land can have taken place. What, then, has exterminated 
so many species and whole genera? The mind at first is irre- 
