Perhaps the next most widely distributed genus is _Helodrilus_ of the family Lumbricidae which occupies Europe and Asia to the extreme east, and is thought also to be indigenous to certain parts of North America. But this range, though equally wide perhaps in mileage, is less impressive than that of _Notiodrilus_, since the land areas inhabited by the genus are continuous--almost so if we accept North America as its real habitat. Here we have a case precisely the opposite of that of _Notiodrilus_; for while there are reasons for regarding _Notiodrilus_ as an ancient form of Lumbricid, there are equally good reasons for regarding the Lumbricidae as the most modern family of earthworms. To find other instances of widely spread genera we must recur to the great family Megascolecidae. There are practically no Geoscolecidae which have a really extensive range. The only instances are _Criodrilus_ and its ally _Sparganophilus_ which occur in America, whether North or South, and in Europe; but as these forms are at least largely aquatic the facts are not quite comparable with those now under consideration. The genus _Dichogaster_ (which includes as synonyms _Benhamia_, _Millsonia_, _Microdrilus_) is unquestionably indigenous to tropical Africa and certain parts of America including the West Indies. It has been also met with in the East; but as the species there occurring, such as for example the species originally described by myself as _Microdrilus saliens_, are of small size, an accidental introduction is quite possible, and it is by no means certain that it has not occurred. In any case the genus is known to possess species which are undoubtedly to be reckoned among peregrine forms--such as _D. bolavi_, which has turned up in Europe. _Gordiodrilus_ and also _Ocnerodrilus_ with its sub-genera have very much the same range as has _Dichogaster_. It is to be noted however that these forms are circumtropical, and that their distribution is thus less continuous than that of _Notiodrilus_; they do not however show the markedly discontinuous range of certain other genera of Megascolecidae. For instance _Octochaetus_ is well known from New Zealand, and, not occurring in the intermediate tracts, is again met with in India. _Hoplochaetella_ is believed by Michaelsen to present us with another precisely similar instance. Then also the genera _Woodwardia_ and _Notoscolex_ are to be found in Australia and again (absent from the immense tract lying in between) in Ceylon. _Megascolex_ has much the same range, showing also this marked and remarkable discontinuity. Stranger still, perhaps, is the range of _Plutellus_ and _Megascolides_, of which the former, chiefly found in Australia and Tasmania, not only extends its habitat to Ceylon but also to North America; it is there represented by Eisen's species _Argilophilus marmoratus_, referred by him, and not unnaturally, to a distinct genus, but placed by Michaelsen in _Plutellus_. _Megascolides_ is