Betapista dekkerae, new genus and new species, is described. The generic diagnoses for Laphania and Scionides are improved after inspection of the holotypes of the type species. Eupolymnia heterobranchia (syn., E. crescentis) is redescribed. Additions to the descriptions, based on study of type material, are made for Laphania boecki (new record, Northeast Pacific), Neoamphitrite robusta (syn., Scionides dux), Neoleprea californica and N. spiralis, Pista brevibranchiata (new record, British Columbia [B.C.], Washington [WA], Japan) and P. fratrella, and Polycirrus californicus (new record, B.C., WA, syn., P. perplexus). Other additions to the descriptions are provided for Amaeana occidentalis (new record, B.C.) and Pista cristata. Two further Pista species (one from the Skagerrak) and five Polycirrus species are characterized but not named. Other new records are Lanassa venusta venusta (B.C.), Lysilla loveni, and Neoleprea japonica (the two latter for Northeast Pacific). Lysilla pacifica, Pista fasciata, and P. fratrella are shown not to be members of the fauna of British Columbia and Washington. Presumably, neither is Polycirrus caliendrum. New observations on the types of the Antarctic Polycirrus kerguelensis and Ereutho kerguelensis are noted.
Eastern Pacific warm temperate to boreal