[Preface of translation:]
Numerous new data on Polychaeta have been collected from different parts of the oceans of the world, and many families therefore require revision. This work is an attempt to summarize information on the Phyllodocidae, Alciopidae, Tomopteridae, Typhloscolecidae and Lacydoniidae from the northern seas of Europe, the Polar Basin and the Northwest Pacific, from the Bering Sea in the north to the Gulf of Tonkin in the south. Collections made by Russian marine expeditions, now in the Zoological Institute of the Academy of Sciences of the USSR (Leningrad), formed the basic material for this summary. Nearly 100 species and lower units of these families are described. The material collected on board the "Vityaz," mainly from the abyssal depths of the Pacific Ocean, contained 10 new species and one new genus, demonstrating the insufficient exploration of the open ocean. Descriptions of most species have been prepared from our material and illustrated by original drawings: only the diagnoses of a few species, not represented in our collections, have been taken from the literature. The systematic survey also includes some pelagic species from the Northeast Pacific, although they probably occur also in the western part of the ocean. Our material often made it necessary to revise the diagnoses of some genera. Keys to species and genera which do not occur in the Polar Basin and the North Pacific have sometimes been included for a more precise definition of the position of some units in the general classification of marine Polychaeta (these are marked with an asterisk in the keys). In the synonymy, reference is generally made to publications which give records of these species in the area studied.
The families dealt with in this work have varying numbers of species and differ markedly in their ecology. The family Phyllodocidae sensu lato is the largest, mainly benthic, and often forms large colonies in coastal zones. The status of the Lacydoniidae, a family which contains only a small number of benthic forms, has been accepted only recently; this family, which was formerly included in the Phyllodocidae, is an intermediate link between the Phyllodocidae and the Nephtyidae. The other families, the Alciopidae, Tomopteridae and Typhloscolecidae, contain only planktonic species, found mainly in the open sea. The Alciopidae certainly have close genetic relations with the benthic Phyllodocidae, but the other two families are very aberrant Polychaeta, which developed characteristic adaptations to pelagic life. The Tomopteridae are probably a very ancient, highly specialized group, and some Typhloscolecidae may be neotenic forms in connection with their transition to ectoparasitism. All the above families, despite their different biology and external morphology, have been placed in the suborder Phyllodociformia. This name was proposed by Levinsen (1882) without his defining its systematic rank (superfamily, suborder). This group is precisely defined in the present work. The suborder Phyllodociformia belongs to the order Phyllodocemorpha (Livanov, 1940), which includes the marine polychaetes with the most primitive characters. Some species described in this work have been compared with related species from other regions, particularly with species received from A. Eliason (Naturhistoriska Museet, Göteborg) and M. Jones and M. Pettibone (Smithsonian Institution, Washington); we have also compared some species with the types of Prof. P. Fauvel, in the Museum National d'Histoire Naturelle, Paris, where I was accorded great consideration by Prof. A. Chabaud. In the description of pelagic Polychaeta we were substantially helped by the plankton collections of the Soviet Antarctic Expedition on the "Ob"; these were identified by N. Tebble (British Museum, Nat. Hist. ) and are at present deposited in the Zoological Institute of the Academy of Sciences of the USSR.
I wish to express my deep gratitude to all specialists, from the Soviet Union and other countries, who placed their material at our disposal. I am grateful to the staff of the Marine Research Laboratory of the Zoological Institute (USSR) for their cooperation during my long research on the marine fauna in their laboratory. Valuable assistance was given during the writing of this book by Profs. A. A. Strelkov and A.V. Ivanov. I am much indebted to V. A. Sveshnikov, who prepared descriptions and drawings of larval forms. Many of the illustrations were done by T. N. Shishlova.
