That earthworms can move upon the surface of the ground at a rapid pace is probably well enough known to everyone, and that they can also burrow with considerable celerity. Multiplying the inches of progress in minutes of time by centuries with the resulting miles, it is quite clear that there is no reason to suppose that an individual earthworm might not enormously extend its range under favourable circumstances. Their powers of locomotion are such that they could in the course of comparatively few centuries people a continent. As a matter of fact these animals are frequently very widely spread upon a given land surface; but on the other hand they are sometimes equally limited. It behoves us therefore to enquire the reasons for the possibility of extended migration and the causes which have led to its restriction. We are now, it must be borne in mind, considering these animals as purely terrestrial animals moving over the surface of the land by their own unaided efforts. We leave out of consideration any possible assistance in crossing water, whether fresh or salt. We have to consider in fact in the present section the earthworm inhabitants of larger and smaller tracts of continuous land such as the African continent, which will serve as an excellent example wherewith to test the facts and inferences. And as a 'control' we can compare this continent with the very different continent of Europe. As an excellent instance, because of the certitude of specific and in most cases of generic distinctions, we may take the Eudrilidae as illustrative of the facts that are to be considered in the present section. That family consists, as will be remembered, of 33 genera at most, which have the following more exact range on the African continent. The genus _Eudriloides_ occurs in British and German East Africa and has been met with as far south as Mosambique and even Durban, in which latter locality it has been thought that it is really an accidentally introduced stranger. _Platydrilus_ is limited to eastern equatorial Africa, thus not having quite the range of _Eudriloides_. The small genera (that is small in numbers of species) _Reithrodrilus_, _Bogertia_, _Megachaetina_, _Metadrilus_, _Notykus_ have the same limitation of range as the last genus. _Metschaina_ has a wider range from tropical North East to lake Tanganyika. _Stuhlmannia_ has a wider range still being found as it is in the Tanganyika district, in tropical North East Africa, and in British and German East Africa near the coast. _Pareudrilus_ reaches still further north while _Nemertodrilus_ is limited to the Mosambique region and to the Orange River district further south. The only remaining genus of this sub-family of the Eudrilidae is _Libyodrilus_ which is purely West African and equatorial.