CH. l] MICROSCOLEX AXD OTHER GENERA. 69 



region. There are altogether sorne nineteen species of the 

 genus of which those that are not American are from New 

 Zealand ; two species are Algerian, and they are closely 

 allied to two American forms that have been met with in 

 Australia, in Italy, and in the island of Teneriffe. This 

 unusually wide range of the species in question seems to be 

 possibly another case of accidental importation by man. In 

 North America there are a few species assigned by Dr 

 Benham and Dr Eisen to the two genera Plutellus and 

 Argilophilus which I cannot differentiate from the purely 

 Australian genus Megascolides, a genus which contains one 

 of the largest earthworms at present known the giant 

 earthworm of Gippsland a creature which grows to a length 

 of six feet. In addition to this genus, which just gets into 

 New Zealand with a single species, Australia has limited 

 to itself the genera Cryptodrilus, Die/aster and Trinephrus\ 

 the latter genus I have thought it advisable to separate 

 from Cryptodrilus on account of the extraordinary fact 

 that its members have in each segment of the body three 

 pairs of nephridia. The division of the genera of Australian 

 Cryptodrilidae is however a matter of the greatest difficulty. 

 In any case it appears to be clear that with the exceptions 

 mentioned these genera do not extend beyond the Austra- 

 lian region and hardly beyond Australia itself. The 

 Oriental region is also fairly well off in worms belonging 

 to this family which are referable to the genera Deodrilus, 

 Typhceus, Microdrilus. Africa has several peculiar forms, 

 including Millsonia, Gordiodrilus and two species which 

 Michaelsen has referred to my Fijian genus Dichogaster, 

 but which may be really members of a different genus ; at 



