THE AMERICAN NATURALIST [Vol. XL 



Synoptic Table for Separation of Described Genera 



(Genera occurring in North America printed in heavy type) 



Capilliform seta^ absent. 



. Dorsal bundles of setno absent. 



Ventral bundles of seta> on all segments Ijegmnmg with the 

 second. Thu'd segment not longer than remaniing segments 

 Sclwmrdella. 



C: Aentral bundles of sottr absent on segment 3-5. Segment 3 

 extremely long Chaetogaster. 



Segment 3 much longer than remainmg segments. Length 

 (of described species) not exceeding 2 mm. . Amplnchceta. 

 Segment 3 not longer than remaining segments. Length (of 

 described species) equal to or exceeding .5 mm. 

 1)1. All setie of dorsal bundle biuncinate .... Paranm'^. 

 D^. Some of the setae of dorsal bundle not biuncinate Ophidonais. 

 Capilliform seta> present in the dorsal bundle. 

 K Dorsal bundle of setie beginning on segment 2, "), or 6. 

 Dorsal bundle of seta> beginning on segment 5 or 0. 



containing paired gills. Usually Innng m tubes composed of 



plant fragments, etc Dero. 



D^ Posterior (mi.1 uithout respiratory pnxrss.-s. 



F. Capdlitnnn , .,t .ln,.,ll.m,dl( uith , m , „ - , .t pi nn.UH nt 



E^. Capillif..nn>rt:.. withoni tcHh. Dorsal i.undlr iH-inniiiir 



