Chap. VI.] OF TEANSITIONAL VAEIETIES. 215 



distribution of closely allied or representative species, 

 and likewise of acknowledged varieties), exist in the 

 intermediate zones in lesser numbers than the varieties 

 which they tend to connect. From this cause alone 

 the intermediate varieties will be liable to accidental 

 extermination ; and during the process of further 

 modification through natural selection, they will almost 

 certainly be beaten and supplanted by the forms which 

 they connect ; for these from existing in greater num- 

 bers will, in the aggregate, present more varieties, 

 and thus be further improved through natural selection 

 and gain further advantages. 



Lastly, looking not to any one time, but to all time, 

 if my theory be true, numberless intermediate varieties, 

 linking closely together all the species of the same 

 group, must assuredly have existed ; but the very 

 process of natural selection constantly tends, as has 

 been so often remarked, to exterminate the parent-forms 

 and the intermediate links. Consequently evidence of 

 their former existence could be found only amongst 

 fossil remains, whbh are preserved, as we shall attempt 

 to show in a future chapter, in an extremely imperfect 

 and intermittent record. 



On the Origin and Transitions of Organic Beings with 



peculiar Habits and Structure, — It has been asked by 



the opponents of such views as I hold, how, for instance, 



could a land carnivorous animal have been converted 



into one with aquatic habits ; for how could the animal 



in its transitional state have subsisted ? It would be 



easy to show that there now exist carnivorous animals 



presenting close intermediate grades from strictly 



terrestrial to aquatic habits; and as each exists by a 



struggle for life, it is clear that each must be well 

 11 



