BIFURCATION IN EMBRYOS OF TUBIFEX. 1 89 



of the old names just quoted. In connection with the following 

 synonymy it should be noted that at present authorities on 

 Lumbricidac do not entirely agree as to whether Helodrilus or 

 Allolobophora should stand as the name of that genus. 



Helodrilus foetidus (Savigny). 



Allolobophora fatida (Savigny). 



Helodrilus caliginosus trapezoides (Duges). 

 Lumbricus trapezoides Duges. 

 Allolobophora trapezoides (Duges). 



Helodrilus subrubicundus (Eisen). 



Allolobophora subrnbicunda Eisen. 



Lumbricus terrestris L., M tiller. 

 Lumbricus agricola Hoffm. 



It thus appears that several of these writers worked on the 

 same species under different names. Failure to recognize this 

 fact has evidently led Weber into the error (p. 339) of listing 

 "Lumbricus trapezoides" and " Allolobophora trapezoides' 1 as 

 separate species. The same writer (p. 347), in discussing the 

 difference of opinion expressed by Kleinenberg and Vejdovsky 

 as to the origin of these monsters, suggests that such a diffeience 

 "may be explained on the basis of the difference in the forms 

 worked on by these two investigatois," evidently regarding the 

 species as different, although Vejdovsky (p. n) states that the 

 material was the same: "Aus meinen embryologischen Unter- 

 suchungen ergibt sich ferner, dass die genannte Art mit clem 

 'Lumbricus trapezoides,' deren Entwicklung Kleinenberg bear- 

 beitete, identisch ist." 



Only three of the above-mentioned reports \vere founded upon 

 an appreciable number of bifid embryos, these three pertaining 

 to the same species. The other records were based upon distinct 

 rarities. All recorded instances fall within the Lumbricidse, 

 the highest family of the Oligochaeta. The present paper 

 presents the first account of embryonic bifurcation in one of the 

 lower families (Tubificidae) of the Oligocha?ta, these anomalies 

 exhibiting remarkable frequency of occurrence and diversity of 

 form. 



