Australian Earthivorms. 225 



were mega or niicroiieplnic, or .sometimes plectoneplnic, and 1 have 

 endeavoured to supplement this witli some account of tlie general 

 distribution of nephridia tliroughout the body, and where pos- 

 sible with microscopic structure. Tliroughout I have used the 

 terms meganephric and uiicronephric, the latter in preference 

 to Benham's word plectonephric, used in most of the original 

 descriptions, but which he has himself since discarded in favour 

 of uiicronephric. 



The structure and arrangement of the nephridia vary to an 

 enormous extent, but there are points of resemblance in some, 

 and with further work on the Australian forms it appears that 

 the nephridia may be of much use for systematic purposes. 



For convenience I have adopted the nomenclature and classi 

 fication of the genera used by Michaelsen in his account of the 

 Oligochaeta of South-west Australia. ^ 



1. Megascolex dorsal is, Fletcher; 



syn. Perichaeta dorsalis, Fletcher (8), p. 618. 



Xo nephridiopores can be seen externally. 



Both micro and meganephridia are present, a condition v.hich 

 Beddard (2), p. 370, regards as characteristic of the genus 

 Megascolex, though as far as I can ascertain, meganephridia 

 have not Ijcen figured liefore for this species. 



Macn>s€oi)i(' Structurt. — On dissection micronephridia are 

 seen to be present throughout all the segments of the body. 

 These are described by Fletcher (S), p. 618, as minute incon- 

 spicuous tufts of tubules. They are arranged somewhat irregu- 

 larly over the body wall in the anterior segments of the body, 

 beconiing less numerous in the posterior parts, where the 

 meganephridia are situated, and being arranged more or less 

 regularly in a single row. In addition to these micronephridia 

 there is a distinct series of well-developed meganephridia which 

 are not mentioned by Fletcher or Spencer. These arc absent 

 from the segments anterior to the male pores, but from this 

 point to the posterior end of the body there is a pair on the 

 ventral surface of each segment with definite funnels opening 

 on either side of the nerve cord. There is in this sjtecies also 



1 Michaelsen, " Die Fauna Sudwest Australiens- Oligochaeta," pp. 117-232, 1907 



