202 Memoirs of the Indian Museum. [Voi,, I, 



this geographical restriction, that it is the sign of consanguinity, that the Maoridrilus 

 group is a natural one, and that the genera which bear the said character are not to 

 be confounded with any species that is devoid of this character. Now, there is firstly 

 BBNHAM's Plagiochœta rossii {On the Old .... Plagiochœta, I.e., p. 284), a species with 

 micronephridial condition (whilst the Maoridrilus group including Plagiochœta is typi- 

 cally meganephridial) , resembling Plagiochœta only in the possession of a great number 

 of setae on each segment, these setae not even being arranged in pairs as in the typical 

 Plagiochœta. It is obvious that P. rossii has nothing to do with the genus Plagiochœta . 

 it is a typical Octochsetine, an Octochaetine with acanthodriline genital apparatus and 

 perichsetine increase of setae, viz., a Hoplochœtella. The genus Hoplochœtella was 

 formerly known only from India, but just this apparent incoherence in geographical 

 distribution confirms my view, for all the Octochœtinœ are found in New Zealand, on the 

 one hand, and on the other in India and adjacent districts. Hoplochœtella is not the first 

 Octochœtine genus living equally in both these far separated territories. The genus 

 Octochœtus is also found both in New Zealand and India. I have to discuss these 

 particular geographical points further on. To this genus Hoplochœtella probably 

 belong also the species Plagiochœta ricardi, BENHAM {I.e., p. 286), and P. montana, 

 BENHAM {I.e., -p. 288). The nephridial system of these species is called micronephric 

 in the first description, whilst BENHAM later, in a footnote in '' On some Edible, 

 etc.," p. 229, declares it to be meganephric. If I understand aright the later note of 

 BENHAM, we here have before us a case of that secondary, only apparently mega- 

 nephric condition I spoke of above, with micronephridia united at each side of the 

 body to form tufts. If this view should prove to be correct, these two species must 

 be regarded as Hoplochœt'ellœ, as well as P. rossii (BENHAM). 



Most difficult is a judgment about a fourth Plagiochœta species of BENHAM, viz., 

 P. lateralis {I.e., p. 282). This species seems really to be meganephric. Though 

 BENHAM did not see the nephridial pores externally he saw them in sections. If this 

 species really be typically meganephric, it should be placed in the sub-family Acantho- 

 drilinœ, but not in the Maoridrilus group of this sub-family {e.g., Plagiochœta) , for 

 the nephridial pores are not alternating, but " in the lateral gap." This species, then, 

 should be the type of a new Acanthodriline genus and be placed at the side of Dinodri- 

 loides. Here I put it in my table of the genera of the sub-fam. Acanthodrilinœ ^ 

 as " Gen. ? (Typus Plagiochœta lateralis, BENHAM)." In the same questionable genus 

 must be placed P. ricardi and P. montana, BENHAM, if they should prove to be 

 meganephric, which I do not believe to be the case. But I am far from being con- 

 vinced of the necessity to form such a genus. I cannot yet give up the idea that 

 even in P. lateralis we have only a modified micronephric condition before us. There 

 is another peculiarity in this species as well as in P. ricardi and P. montana which makes 

 me believe them to belong to the sub-family Octochœtinœ, viz., the characteristic ap- 

 paratus of strong transverse muscles in the vicinity of the prostates and male pores. 

 This is a character very often found in the Octochœtinœ, — in the genus Octochœtus as well 



' W. Michaelsen, Oligochaeta; in Die Fauna Südwest- Australiens, bd. i, p. 140. 



