330 FORMS OF LIFE CHANGING 



well with the theory of natural selection. We need not 

 marvel at extinction ; if we must marvel, let it be at our 

 own presumption in imagining for a moment that we under- 

 stand the many complex contingencies on which the exist- 

 ence of each species depends. If we forget for an instant 

 that each species tends to increase inordinately, and that some 

 check is always in action, yet seldom perceived by us, the 

 whole economy of nature will be utterly obscured. When- 

 ever we can precisely say why this species is more abundant 

 in individuals than that; why this species and not another 

 can be naturalized in a given country; then, and not until 

 then, we may justly feel surprise why we cannot account 

 for the extinction of any particular species or group of 

 species. 



ON THE FORMS OF LIFE CHANGING ALMOST SIMULTA- 

 NEOUSLY THROUGHOUT THE WORLD. 



Scarcely any palaeontological discovery is more striking 

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

 taneously throughout the world. Thus our European Chalk 

 formation can be recognized in many distant 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 Tierra 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 

 present an unmistakable 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 characterized 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 formations either above or below, occur in 

 the same order at these distant points of the world. In 

 the several successive palaeozoic formations of Russia, West- 

 ern 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 parallelism in the successive 

 forms of life, in the palaeozoic and tertiary stages, would 



