98 EARTHWORMS AND THEIR ALLIES [oh. 



of which I am myself responsible) is due to the fact 

 that in earlier days when nothing was known about 

 the geographical distribution of this group of animals 

 it was thought by no means unreasonable that a 

 given genus represented by several species should 

 range over the globe. This fact coupled with im- 

 perfect description of structural details led to the 

 multiplication of supposed species, a position which 

 is no longer tenable. This worm is quite as abundant 

 in gatherings from all parts of the world as is Ponto- 

 scolex cprethrurus ; and in addition to the countries 

 inhabited by the latter, Eudrilus eugeniae has been 

 met with in New Caledonia : tropical Africa is 

 probably its original home. 



The two families that have been hitherto considered 

 offer no further instances, among their many species, 

 of worms with so wide a range as those just dealt 

 with. There are indeed one or two forms, e.g. Crio- 

 drilus and Glyphidrilus, which have a considerable 

 range though not nearly equalling that of Eudrilus 

 and Pontoscolex. These are, however, aquatic forms 

 and the range of aquatic forms is determined as far 

 as we can see by a different series of causes to that 

 of terrestrial forms, which are referred to later. 



Among the Moniligastridae we have apparently 

 an instance of a peregrine form. The genus itself 

 has its headquarters in Ceylon and extends a little 

 way in other eastern regions ; there is, however, one 



