No. 478] 



OHIO NAIDIDM 



Prostomiuin develoi)ed into a tentacular process 

 Stylaria. 



G-. Prostomium rounded Nais. 



Dorsal bundle of setae beginning on segment 2. 



Anterior capilliform seta^ partly covered by filamentous gills 

 Branchiodrilus. 



D^. No filamentous gills present. 



Dorsal bundle usually composed entirely of capilliform 

 seta?. Prostorniinn developed into a long tentacular pro- 

 cess Pristina. 



Dorsal bundle composed in part of biuncniate or of short 



tentacular process Naidium. 



B^. Dorsal bundle of setie beginning on segment 12-20 Ha monais. 



Genus chaetog aster K. Baer, 1827 



Prostomium rudimentaiy, coalesced with segment 1 ; 2 ventral 

 bundles of sette on a segment, these absent on segments 1 and 3-5. 

 SetfB uncinate. Pharynx large and wide. Esophagus small, not 

 longer than pharynx; 1 pair of transverse vessels count'cts the 

 dorsal and the ventral vessels. Loiigitm liii.il ( Miiimis-urtvs of 



