ERKANÏIATE POLYCHAETA OF JAPAN. 147 



uniramous or biramous, with a dorsal and a ventral cirrus, accom- 

 panied with acicnlœ and bundles of bristles. Pygidium with 2 

 anal cirri ventrally to anal opening. Proboscis divided into two 

 rings in the protruded state, nearly always with paragnathi, rarely 

 naked or with soft papillae ; with 2 maxillae. 



Key to the genera. 



fC . Parapoclium TiiuLamous Lycaslis. 



a". Parapodium birainons. 



h'. With simple dorsal ciirus. 



c'. With superior and inferior ligiila Nereis. 



c" . Without superior ligula CeratocepJiale. 



h". With featliered dorsal cirrus Dendr one reis. 



Genus JS^erels L. 



Prostomium rotundate-pentagonal or triangular, narrowed 

 anteriorly ; both pairs of eyes in the posterior parts ; tentacles 2, 

 subulate, frontally situated ; palpi 2, biarticulated, with basal part 

 stout and long, with distal part soft, short and retractile. First 

 body-segment with neither parapodia nor bristles, with 2 pairs of 

 tentacular cirri on each side of prostomium and affixed to the 

 segment. 



Parapodia laranious, supported by 2 acicuLu ; 1 ligula on 

 ventral ramus and 2 on dorsal ramus ; both dorsal and ventral 

 cirri présent, lîristles usually jointed, the shaft with dense 

 transverse striations ; setose on dorsal, and either setose or falcate 

 Ol- bol 11 Oll ventral, i-aiiius; .sometimes unjointod bristles present 

 among joint<.'d ones. 



Proboscis protrusible, divided into two (maxillary and basal) 

 j-ings by a circular furrow ; maxillae crooked and mostly serrated ; 



