LEE BARKER WALTON 41 



slender teeth of the ventral setae are a striking character- 

 istic of this species. 



Genus Pristina Ehrenberg, 1831 



Prostomium usually developed into a tentacular process. 

 Ventral bundle composed of biuncinate setas. Dorsal 

 bundle beginning on the 2nd segment, composed of capil- 

 liform set£e. Testes in 7th, ovaries in 8th, spermathecas 

 in 7th segments (description of sexual organs based on 

 observation of one species, P. leidyi) . 



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

 ica, and Java; 6 species. 



The species may be separated by the following table. 

 While it is possible that a careful study of P. oequiseta, P. 

 longiseta, and P. flagelliim, may show that those respon- 

 sible for the descriptions have overlooked the existence of 

 the small teeth present in P. leidyi and P. serpentina, it ap- 

 pears evident that the species are distinct on other grounds. 



A^. Setje of dorsal bundle smooth. 



B^. Last segment not provided with finger-like processes. 



C^. Dorsal setse of 3d segment not decidedly longer than those 



of other segments; length 7 to 8 mm P. cequheta. 



(Europe.) 



C^. Dorsal sets of 3d segment much longer than those of other 



segments P. longiseta. 



(Europe.) 



B^. Last segment provided with 3 (2 lateral and 1 median) finger- 

 like processes projecting posteriorly P. flagellum. 



(N. America, S. America.) 



A^. Setx of dorsal bundle provided with numerous fine but distinct 

 teeth. 

 B^. Capilliform seta: of dorsal bundle approximately 3 5jLt long. 

 Those of the 3d segment twice as long as the others P. leidyi. 



(N. America, S. America.) 

 B^. Capilliform setje of dorsal bundle approximately 300//, long. 

 Those of the 3d segment not longer than others. 

 C^. Teeth of ventral setse subequal. Number of segments ap- 

 proximately 14 P. serpen fina. 



(N. America.) 



C^. Distal teeth of ventral setae longer than proximal teeth. 

 Number of segments 18 to 30 . . . P. proboscidea. 



(S. America.) 



