SECTION III 

 KEY TO THE NORTH AMERICAN FRESHWATER POLYCHAETA 



Anterior end of body modified to form branchial crown of 



filaments surrounding the mouth (Fig. 2a, b) . Prostomium 

 reduced. Parapodia reduced; with simple capillary setae 

 and hooks . Sedentary 



Anterior end of body without branchial crown. Prostomium 

 well developed usually with eyes and sensory appendages 

 (Fig. 2c). Parapodia well developed; usually with compound 

 as well as simple setae. Errant 



a 



Fig. 2. a- Mercierella enigmatiaa, lateral view anterior end; 

 b- Manyunkia speoiosa, dorsal view anterior end; c- Nereis 

 limniaola, dorsal view anterior end. 



2(1) Branchial crown with stalked operculum showing considerable 

 degree of variability (Fig. 3a-c) . Thoracic region with 

 well defined collar [see Fig. 2a). With calcareous tube: 



MevcievelZa enigmatica 

 Branchial crown without stalked operculum. Thorax lacking 



collar (Fig. 2b). Tube membranous or sandy: Manyunkia speciosa 



