118 DARWmiAFA. 



because, by tlieir complete extinction in Soiitli Amer- 

 ica, the line of descent was there utterly broken ? 

 Upon the ordinary hypothesis, there is no scientific 

 explanation possible of this series of facts, and of 

 many others like them. Upon the new hypothesis, 

 " the succession of the same tj^Des of structure within 

 the same areas during the later geological periods 

 ceases to be mysterious, and is simply explained by 

 inheritance." Their cessation is failure of issue. 



Along with these considerations the fact (alluded 

 to on page 98) should be remembered that, as a general 

 thing, related species of the present age are geographi- 

 cally associated. The larger part of the plants, and 

 still more of the animals, of each separate country are 

 peculiar to it ; and, as most species now flourish over 

 the graves of their by-gone relatives of former ages, 

 80 they now dwell among or accessibly near their 

 kindred species. 



Here also comes in that general " p>arallelism be- 

 tween the order of succession of animals and plants 

 in geological times, and the gradation among their 

 living representatives " from low to highly organized, 

 from simple and general to complex and specialized 

 forms ; also " the parallelism between the order of 

 succession of animals in geological times and the 

 changes their living representatives undergo during 

 their embryological growth," as if the world were one 

 prolonged gestation. Modern science has much in- 

 sisted on this parallelism, and to a certain extent is' 

 allowed to have made it out. All these things, which 

 conspire to prove that the ancient and the recent forms 

 of life " are somehow intimately connected together 



