284 OLIGOCHAETA 



which concerns the seta, and is mentioned in the diagnosis of the two worms 

 given here. Another difference referred to by TAUBEB is that in 0. barbata 

 the ova are deposited in October and November 1 . As TAUBEK pointed out, SEMPER 

 also confused these two species. So, too, DIEFFENBACH (p. 99) who regarded the 

 individuals with bifurcate setae in the dorsal bundles as a variety of N. elinguis. The 

 species is figured by MULLER, VAILLANT (6, PI. xxii, figs. 14. 15). FLOERICKE has 

 applied the name of N. greeffi to a worm which I regard as a variety of the present 

 species ; the ventral setae are, as in N. elinguis, of equal length throughout the body ; 

 whereas in N. barbata those upon the first four segments are longer. 



(2) Nais elinguis, 0. F. MULLER. 



N. elinguis, 0. F. MULLER, Verm, terrestr. vol. i, pt. ii, 1774, p. 22. 

 Opsonais elinguis, GERVAIS, Bull. Ac. Roy. Belg., 1838, p. 17. 

 N. rivulosa, LEIDY, Journ. Acad. Nat. Sci. Philad., 1850, p. 43. 



Definition. Dorsal seta bundles with capilliform and hasfiform setae, one to three in each 

 bundle. Eyes present. Hob. Europe; N. America. 



I think that LEIDY'S N. rivulosa cannot be differentiated from N. elinguis. This 

 is also the opinion of VAILLANT (6, p. 371) and D'UDEKEM (5, p. 20). VAILLANT, 

 however, suggests as a possible difference the greater slenderness of the ventral setae 

 in the American species. 



(3) Nais lacustris (LINNAEUS). 



Nereis lacustris, LINNAEUS, Syst. Nat., 1767, p. 1085. 



Nais proboscidea, 0. F. MULLER, Verm, terrestr. vol. i, pt. ii, 1774, p. 21. 



Stylaria proboscidea, EHUENBERQ und HEMPRICH, Symb. Phys., 1831. 



Stylaria paludosa, LAMARCK, Hist. An. sans Vert., 1816, iii, p. 224. 



Stylinais proboscidea, GERVAIS, Bull. Ac. Roy. Belg., 1838, p. 18. 



Stylaria lacustris, JOHNSTON, Cat. Worms, 1865, p. 70. 



P Stylaria phyladelphiana, CzERNiAVSKY, Bull. Soc. Nat. Mosc., 1880, p. 309. 

 ? Stylaria fossularis, LEIDY, P. Acad. Nat. Sci. Philadelphia, 1852, p. 287. 



non-N. lacustris, DALYELL, Powers of the Creator, ii, 1853, p. 130 2 . 



Definition. Length, i$m.; number of segments, 25. Prostomium much elongated. Dorsal 

 sela bundles with capilliform setae only. Eyes present. Hab. Europe and America. 



1 As VEJDOVSKY (24, p. 29) has pointed out, the ova of 0. elinguis, though usually laid in June, are 

 sometimes deposited in autumn, so that this difference is not absolute. 

 J Chaelogasfer. 



