118 EARTHWORMS AND THEIR ALLIES [CH. 



vast extents of country greater in diameter than the 

 African continent, but there are also many species 

 which range as widely or nearly as widely as the 

 case may be as the genus to which they belong. 

 Thus the species of Allolobo^yhora (we do not trouble 

 about the newer sub-divisions as they hardly affect 

 the facts to be emphasised), A. caliginosa, A. long a, 

 A. rubida, A. clilorotica, A. octaedra, A. coustricta, 

 A. heddardi, Lumbrictis terresh'is, L. castaneus, have 

 an enormously wide range over what is generally 

 termed the Palaearctic region, extending also in some 

 cases into the Nearctic. It is true no doubt that the 

 majority, indeed perhaps all, of these are, like certain 

 species of Dichogaster mentioned above, among those 

 forms termed peregrine which have the capability of 

 living in every quarter of the globe to which they 

 have apparently been conveyed by man. But there 

 remain many species which have a very extended 

 habitat in the northern hemisphere, and in any case 

 the genera and the species are there truly indigenous 

 and widely spread. 



It would thus appear that the capability for inde- 

 pendent migration varies greatly among earthworms. 

 Of the types selected for consideration the Eudrilidae 

 are the slowest movers ; the genus Dichogaster comes 

 next, while the power of migration possessed by the 

 genera Allolobophora and Lumbricus is very much 

 greater. Assuming for the moment the correctness 



