xn INTRODUCTION. 



the stages of their retreat away from the evolutionary centre, in avoidance 

 of the competition from the improved races that have succeeded them. 



A study of the various groups attests the accuracy of this important 

 generahzation and law, and demonstrates that the distribution and dis- 

 persal of animal life generally is not that illogical process, as some aver, 

 in which the weak and strong forms of life equally multiply, increase in 

 numbers and promiscuously invade each other's territories ; but, as it 

 cannot be too strongly emphasized, the distribution over the globe of all 

 life is based upon the domination, greater increase, and consequent 

 spreading of the stronger and most recently evolved forms, and the 

 enforced retirement before them of the weaker and less adaptable species, 

 which in their turn press upon and successfully compete with the still 

 more primitive species that preceded them. 



This is abundantly manifest when the phenomena are iuipartially 

 studied and it becomes clear that the representatives of weaker races are 

 not advancing and never do permanently advance towards the European 

 region, but in every case are retreating further and further from the 

 original evolutionary region before the more powerful species originating 

 there, and which as a consequence of their predominance and adaptability 

 increase rapidly in numbers, and must therefore perforce extend their 

 boundaries. 



Still further confirmation is given by our experience of European 

 species when transferred to a new country amidst a palpably weaker fauna 

 or flora, as in New Zealand ; under such circumstances the intruders 

 prosper amazingly to the detriment and eventual extirpation of the 

 indigenous species ; whilst on the contrary any attempts to permanently 

 naturalize the organisms of a weak country within the European region 

 are foredoomed to failure. 



The highest evolution is shown by the marvellous adaptability and pre- 

 dominance of the European forms, and is internally evidenced by a greater 

 concentration of the oesopliageal ganglia within the cephalic region, while 

 a potential ability to resist hard conditions may be conferred by the 

 elaborate intestinal coiling, which gives a greater digestive and absorptive 

 power, and therefore will enable the maximum nourishment to be derived 

 from the most meagre amount of food. 



This predominance of the European forms of life is not confined to 

 iiiollnsks, as Prof. Alfred Newton, our most philosopliical ornithologist, 

 lias averred tliat amongst the birds also, the wealcer types have been very 

 generally eliminated in the western palrearctic region, and that all the 

 species are of the most dominant character, with the greatest powers 

 of dispersal, and these features are as strongly shown by the mammals 

 and other groups. 



