1885.] NEW-ZEALAND EARTHWORMS. 823 



mentioned, the setae are in four series of pairs, the nef)hridia 

 similarly alternate in position from segment to segment (woodcut, 

 fig. 2). There does not, however, appear to be any regularity in this 

 alternation : sometimes the p.ephridiaof tive or six consecutive segments 

 open bv the same series of setae on both sides of the body. In other 

 segments there is an asymmetry of the nejjhridia of the two sides of the 

 body : for example, the left-hand gland may open by the dorsal, while 

 the right-hand gland opens by the ventral pair of setae ; occasionally 



Fig. 2. 



Acanthodrilus novm zelancLim. — A portion of the body viewed from tlie side. 

 n, nephridial pores ; s, setas of ventral pair. 



there is a regular alternation coupled with absolute symmetry in the 

 position of the nephridial pores. Moreover, no two individuals of 

 either species that I examined were exactly alike in these respects ; 

 and it was impossible to distinguish one species from the other by 

 the position of the nephridial pores ; occasionally the nephridia, one 

 or both, were found to coincide at the same series of setae as the 

 male and female genital ducts, but in no case did I observe a 

 similar coincidence of nephridium and spermatheca. 



Another })oint of interest in connection with the ncjihridia of these 

 two species has not been recorded by Perrier in PluteUus : tlie two 

 seriesof nephridia, dorsal and ventral, show otiier indications besides the 

 varying position of their apertures of being the vestiges of two com- 

 plete series; in every msi&wce it was found possible to distinyuish 

 the nephridia of each series by morphological differences. In all the 

 nephridia the muscular portion which forms tiie distal extremitv of 



