LEE BARKER WALTON 37 



Nah lacnstris Beddard, Monogr. .Olig., p. 284, 1895; Michaelsen, Das Tierreich, 

 Oltgochceta, p. 3 3, 1900. 



S. paluJosa, S. fossularis Leidy, ?roc. Acad. Nat. Set. Phila., vol. 5, pp. 286, 

 287, 1852. 



S. phyladelphiana, S. scotica Czerniavsky, Bull. Soc. Imp. Nat. Moscou, vol. 5 5, 

 no. 4, p. 309, 1880. 



Prostomium developed into a long tentacular process. 

 Eyes usually present. Distal teeth of ventral setae un- 

 equal. Dorsal setas capilliform with 1 long and 1 to 2 

 short in each bundle. All long setx of each bundle ap- 

 proximately of the same length. Clitellum in sexually 

 mature forms on segment 6. Male pores on 6th segment. 

 Sperm duct in 5 th, spermatheca: in 5 th segment. Length 

 10 to 15 mm. Number of segments about 2 5. 



Europe, North America (Pennsylvania, Ohio, IlHnois). 



A large number of specimens were observed which 

 must at present be referred to this species. Michaelsen 

 notes the length of N. lacnstris as varying between 10 and 

 15 mm., while the length of those found at Cedar Point 

 was always from 4 to 5 mm. The teeth of the ventral 

 set£e are also considerably shorter and more obtuse than 

 illustrated in the figures of Vedjovsky ('84), Tauber, and 

 others. Furthermore, the length of the tentacular proc- 

 ess in those forms observed, did not exceed the length of 

 the long capilliform setse while Miiller (1774) notes the 

 length of the tentacular process as equivalent to ten seg- 

 ments of the bod)^ The synonymy of S. lacnstris is in a 

 confused condition, and it is possible that careful study 

 will establish one or more new species in the genus. 



The imperfect descriptions given by Leidy ('52b) to 

 the species described by him as S. paludosa and S. fossularis, 

 will not permit their separation from S. lacnstris. 



Genus Nais Miiller, 1774 



Prostomium rounded. Ventral bundle with biuncinate 

 setas. Dorsal bundle beginning on the 6th segment with 

 capilliform and variously pointed short setas. Testes in 

 5th, ovaries in 6th, spermathec*e in 5th segments (in 

 species where sex organs have been observed) . 



In fresh water. Europe, North America, South Amer- 

 ica, and East India; ten species. 



