FORMS OF LIFE CHANGING 373 



a given country; then, and not until then, we may justly feci 

 surprise why we cannot account for the extinction of any 

 particular species or group of species. 



ON THE FORMS OF LIFE CHANGING ALMOST SIMULTANE- 

 OUSLY THROUGHOUT THE WORLD 



Scarcely any palseontological discovery is more striking 

 than the fact that the forms of life change almost simulta- 

 neously throughout the world. Thus our European Chalk 

 formation can be recognised in many distinct regions, under 

 the most different climates, where not a fragment of the 

 mineral chalk itself can be found; namely in North America, 

 in equatorial South America, in Ticrra del Fuego, at the 

 Cape of Good Hope, and in the peninsula of India. For at 

 these distant points, the organic remains in certain beds pre- 

 sent an unmistakeable resemblance to those of the Chalk. It 

 is not that the same species are met with ; for in some cases 

 not one species is identically the same, but they belong to the 

 same families, genera, and sections of genera, and sometimes 

 are similarly characterised in such trifling points as mere 

 superficial sculpture. Moreover, other forms, which are not 

 found in the Chalk of Europe, but which occur in the forma- 

 tions either above or below, occur in the same order at these 

 distant points of the world. In the several successive palaeo- 

 zoic formations of Russia, Western Europe, and North 

 America, a similar parallelism in the forms of life has been 

 observed by several authors; so it is, according to Lyell, with 

 the European and North American tertiary deposits. Even 

 if the few fossil species which are common to the Old and 

 New Worlds were kept wholly out of view, the general par- 

 allelism in the successive forms of life, in the palaeozoic and 

 tertiary stages, would still be manifest, and the several for- 

 mations could be easily correlated. 



These observations, however, relate to the marine inhabi- 

 tants of the world: we have not sufficient data to judge 

 whether the productions of the land and of fresh water at 

 distant points change in the same parallel manner. We may 

 doubt whether they have thus changed: if the Megatherium, 

 Mylodon, Macrauchenia, and Toxodon had been brought to 



