1904.] EARTHWORMS FROil XEW ZEALAXD. 259 



which these foui' species have in common, and in which they 

 agree with Tokea, is the coexistence in the postei-ior segments of 

 meganephridia and micronephridia. 



Let us turn to Beddard's conception of the limits of the genus 

 Megascolides ( = JYotoscolex Fl.) and Cryjytodrilus Fletcher (the 

 history of which is well given in his Monograph, pp. 445 et seq.). 

 He draws attention to the fact that in nearly all the worms 

 described by Spencer, and in a considerable number of those 

 described by Fletcher (at any rate in such cases in which sufficient 

 information is given to enable a comparison to be made), there is 

 a. correlation between certain of the internal organs (p. 447), viz, 

 that " they have either (1) paired neiDhridia, tubular spermiducal 

 glands, and last pau' of hearts in the 12th segment ; or (2) diffuse 

 nephridia, lobate glands, and last heart in the 13th segment." 

 He decides to regard those species ^^-ith the first set of characters 

 as l^elonging to the genus " Jlegascolides," and those with the 

 second group as " Cryjitodrilus.'^ He admits that there are 

 exceptions to these correlations. 



It thus comes about that Michaelsen uses the generic name 

 Jlegascolides for " micronephric," whereas Beddard employs the 

 same name for " meganepln'ic '"' Avorms. Bu.t the meganephric 

 species are placed by Michaelsen in the genus Plntellus, which 

 is thus extended to include species previously attriliuted to 

 Argilojihilus of Eisen, Megascolides oi various authors, Cri/jitodrilus 

 of Fletcher, as well as Plntellus of Peri-ier and Benham. 



Thus we have this unfortunate confusion in the employment of 

 generic names : — 



Megascolides M'Coy, in Michaelsen's sense, 



= Notoscolex (part) Fletcher, 



= Cryptodrilus (part) Beddard ; 

 Xotoscolex Fletcher, as used by Michaelsen, 



= Notoscolex Fl. + Cryptodrilus Fl. 



= Jlegascolides (part) Spencer ; 

 Cryptodrilus, in Beddard's sense, 



= Cryptodrilus Fletcher, 



= Megascolides (part) Spencer, 



= Notoscolex (part) Fletcher ; 

 Jlegascolides, in Beddard's sense, 



= Cry2)todrilus (part) Fletcher, Spencer, 



= Jlegascolides (part) Spencer, 



= Argilophilus Eisen, 



= Phttelhcs Perrier. 



It is natural that in a group like Earthworms a mixture and 

 confusion of this sort is likely to arise as knowledge advances ; 

 and it remains for Prof. Baldwin Spencer with the large stock of 

 material in his possession, to endeavour to find some more satis- 

 factory method of discriminating between genera than those 

 usually employed. 



Of course the correct name that should be applied to the genera 



17* 



