112 EARTHWORMS AND THEIR ALLIES [ch. 



P. aucldandiciis and the Lumbricid Helodrilus con- 

 strictus. There were also four species of purely 

 aquatic Oligochaeta which we shall leave aside from 

 the present enumeration, as their range in space is 

 a matter requiring a different explanation from that 

 of the terrestrial forms. Here we have a series of 

 worms, all of which, save the widely spread Lumbricid, 

 are apparently absolutely indigenous to the islands 

 mentioned since they are all different as species from 

 those found elsewhere. Indeed there is a whole 

 genus Leptodrilus, consisting, it is true, of but two 

 species, which is a native of the Campbell and Auck- 

 land islands and of those only. The other genera are 

 found in the antarctic region, while Pelodrilus is 

 still more widely spread. 



These facts as will be observed contrast about as 

 strongly as they can with those supplied by the fauna 

 of Honolulu and its adjacent islands. Not only are 

 the worms of the antarctic islands different species 

 from those found elsewhere, but the majority of them 

 do not consist of widely ranging peregrine forms. It 

 appears therefore most probable that these islands are 

 not oceanic islands but a portion of the former existing 

 northern portion of the antarctic continent. Were the 

 species identical with those of New Zealand this 

 conclusion would have of course to be reconsidered. 

 The barriers to migration (see chap, viii) explain the 

 contrast recorded in the foregoing pages. 



