42 THE SHORTER SCIENTIFIC PAPERS 



PRISTINA SERPENTINA n. sp. 



Prostomium developed into a long tentacular process, 

 usually 0.2 to 0.3 mm. in length. Eyes absent. Digestive 

 tract with stomach in the anterior part of the 8 th seg- 

 ment. Dorsal bundle beginning on the 6th segment, 

 composed of 2 long (iOOix), 1 medium (100/x) capilli- 

 form setx, and 2 to 6 short needle-like (30ju, to 50ja) setae. 

 Ventral bundle composed of 5 to 6 biuncinate (SOfi to 

 80/x) setse with subequal teeth. Length 2.2 mm. Num- 

 ber of segments in an individual about 15. 



Cedar Point, Sandusky, Ohio. 



This species of Pristina was exceedingly abundant at 

 Cedar Point, and on first examination was apparently to 

 be placed near P. cequiseta Bourne. Closer examination, 

 however, demonstrated the existence of fine teeth on the 

 set£e of the dorsal bundle. The difference in the form of 

 the distal teeth of the ventral setas distinguishes it from 

 P. proboscidea Beddard, now recognized by Michaelsen 

 ( : 5 ) as a valid species. 



Genus Naidium O. Schmidt, 1847 



Prostomium either rounded, pointed, or developed into 

 a short tentacular process. Dorsal bundle beginning on 

 the 2d segment, composed of capilliform, or needle-like, 

 and biuncinate setse. Ventral bundle composed of bi- 

 uncinate setse. 



Fresh water. Middle Europe, East India, North Amer- 

 ica, and South America; six species. 



A^. Prostomium not developed into a tentacular process. 



B^. Number of segments composing an individual usually 1 5 to 

 30 (32 to 40, N. hiteum) . Biuncinate setae in dorsal bundle. 

 C^. Prostomium rounded or pointed, species small, not exceed- 

 ing 5 mm. in length. 



D^. Number of segments in an individual 20, posterior part 

 of brain developed into 4 pronounced lobes N. bilobatum. 



(Europe.) 



D^. Number of segments in an individual 15 to 16. 



E^. Capilliform setx shorter than the diameter of the body. 

 Teeth of dorsal biuncinate setae approximate N. uniseta. 



(Europe.) 



