igoS.] W. M1CHAEI.SKN : Oligochceta of the Indian Empire and Ceylon. 203 



as in Eutyphoeus , — while it is not present in the typical species of Plagiochœta. I hope 

 the further examination of the nephridial system of the species, as promised to us by 

 BENHAM, will settle these questions. I, in the meanwhile, must be contented with 

 the result, that P. rossii surely, and P. ricardi and P. montana probably, belong to the 

 genus Hoplochcetella, while the systematic position of Plagiochœta lateralis, which is 

 certainly no Plagiochœta , remains an open question. 



As for the geographical aspect of BENHAM' s arguments regarding the near affinity 

 between Octochœtus , Dinodrilus and Notiodrilus (Eodrilus), I cannot understand the 

 meaning of it. BENHAM says : " . . . . moreover their presence (that of OdocÄ^^^^s and 

 Dinodrilus) in New Zealand indicates their close association therewith (with Notiodri- 

 lus)." Now on the one hand Notiodrilus Œodrilus) is a genus with a world-wide distri- 

 bution, occurring not only in New Zealand, but also in New Caledonia, Australia, 

 Madagascar, South Africa, Tropical Western Africa, South Patagonia, Chile, Central 

 America and Mexico, and this distribution, with the exception perhaps of the Tropical 

 West African locality, was known when BENHAM wrote that sentence, published 

 in April, 1905. On the other hand Octochœtus, as has been known since the 

 year 1899, is endemic in India as well as in New Zealand. Its distribution, then, is 

 quite different from that of Notiodrilus {Eodrilus) , and there is nothing in the 

 distribution of these genera, that could favour the idea of a special relationship 

 between them. This distribution just confirms my view of the systematic substantial- 

 ness of the sub-family Octochœtinœ, for all its genera are endemic in these districts, 

 either in one of them or at the same time in both of them. The genus Octo- 

 chœtus is endemic in New Zealand and India, Dinodrilus in New Zealand, Hoplo- 

 chœtella in New Zealand and India, and finally Eutyphoeus in India and the adjacent 

 districts of Burma (and Ceylon ?). There could hardly be a distribution more 

 characteristic than this. I need not explain to any zoo-geographer that the dis- 

 continuation of these two regions of distribution in the Octochœtinœ is quite a common 

 matter in geographical distribution, the two regions, New Zealand and India, 

 perhaps together with a third region, Madagascar, the home of Howascolex,^ represent- 

 ing the peripheral parts of a circular distribution, the internal parts of which have been 

 obliterated by the mighty development of younger and stronger forms, in this case of 

 the vigorous genus Pheretima, which, from Burma to New Hebrides in one direction 

 and Japan in another, has suppressed and partly exterminated all other genera of 

 earthworms, those of its own phylum or sub-family as well as those of other tribes. 



GEN. OCTOCHŒTUS. 



This genus is represented by six species in the examined collections. I shall 

 discuss the relation of this genus to Eutyphoeus further on in connection with the 

 special discussion on the latter. 



I The genus Howascolex, MICHLSN., from Madagascar, till now regarded as belonging to the sub- 

 family AcanthodrilincB, .-^eems to represent a link between this sub-family and the Octochcetinœ. It 

 might be justifiable to place it among the Octochcetince at the side of Octochcetus. 



