192 CHAPTER II 



TABLE 4. Animals found on ballast-places in S. W. England. 



The Carabid beetles 



Special attention was paid to Carabid beetles, every specimen of this group being 

 collected in order to get an idea of the relative abundance of the different species. 

 The results are given in table 5. 



From the survey given there, it seems appropriate to draw attention to the 

 following points: 



1. Of 83 Carabid species collected on the ballast places, 21 are here regarded 

 as introduced into North America, that is 25 per cent. 



2. Of 40 Carabid species regarded as introduced into North America from 

 Europe (table 2, p. 144), these 21 species make no less than 53 per cent. If 3 species 

 are removed from the list, because they are not permanent inhabitants of the 

 British Isles (Amara anthohia, Carabus auratus and cancellatus) and 2 species 

 {Clivina collaris and /owor), found by other collectors on the Avon banks at Bristol 

 (p. 186), are added to the "ballast species", it appears that out of 37 North Ameri- 

 can species of Carabidae which may have been introduced from the British Isles, 

 no less than 23, that is 62 per cent, have been observed on the stated or supposed 

 ballast-places of southwestern England. 



3. Another point of importance is the frequency and abundance of the "emigrants" 

 among Carabids collected on the ballast-places (Diagr. 3 and 4); only the occur- 

 rence on "waste places" is here considerd. If frequency is determined by the num- 



