﻿MARINE 
  POLYCHAETE 
  WORMS 
  — 
  PETTIBONE 
  263 
  

  

  dorsal 
  cirri 
  shorter 
  than 
  the 
  body 
  width. 
  Ventral 
  cirri 
  thick, 
  pointed, 
  

   almost 
  as 
  long 
  as 
  parapodial 
  lobes. 
  Neurosetae 
  all 
  composite, 
  distal 
  

   blades 
  distinctly 
  bidentate, 
  finely 
  spinous 
  along 
  cutting 
  edge; 
  blades 
  

   of 
  upper 
  setae 
  longer, 
  becoming 
  gradually 
  shorter 
  in 
  lower 
  part 
  of 
  

   bundle 
  with 
  upper 
  ones 
  about 
  twice 
  the 
  length 
  of 
  lower 
  ones. 
  Proboscis 
  

   with 
  a 
  distal 
  row 
  of 
  10 
  papillae; 
  transparent 
  chitinous 
  lining 
  with 
  a 
  

   translucent 
  bluish-gray 
  dorsal 
  tooth, 
  with 
  distal 
  rim 
  smooth. 
  Color: 
  

   In 
  alcohol: 
  Irregularly 
  dotted 
  with 
  black 
  pigment 
  both 
  dorsally 
  and 
  

   ventrally. 
  (Epitokous 
  forms 
  have 
  capillary 
  setae 
  beginning 
  on 
  seg- 
  

   ments 
  12-15 
  — 
  Malmgren, 
  1867.) 
  

  

  New 
  records. 
  — 
  Arctic 
  Alaska: 
  Off 
  Point 
  Barrow, 
  36-78 
  fms., 
  up 
  

   to 
  15 
  miles 
  from 
  shore, 
  on 
  bottoms 
  of 
  rocks, 
  stones, 
  and 
  worm 
  tubes 
  

   (2 
  stations, 
  2 
  specimens). 
  

  

  Distribution. 
  — 
  Arctic 
  Alaska; 
  Spitsbergen; 
  Bering 
  Sea. 
  In 
  low 
  

   water 
  to 
  78 
  fathoms. 
  

  

  Family 
  Nereidae 
  

  

  Prostomium 
  distinct, 
  with 
  four 
  eyes, 
  two 
  frontal 
  antennae, 
  two 
  bi- 
  

   articulated 
  palps 
  (fig. 
  30, 
  a). 
  Four 
  pairs 
  tentacular 
  cirri; 
  buccal 
  or 
  

   tentacular 
  segment 
  usually 
  apodous 
  and 
  achaetous. 
  Parapodia 
  

   usually 
  biramous 
  (except 
  first 
  two 
  pairs), 
  with 
  dorsal 
  and 
  ventral 
  

   cylindrical 
  cirri, 
  two 
  or 
  three 
  notopodial 
  ligules 
  and 
  one 
  neuropodial 
  

   ligule 
  (fig. 
  30, 
  6, 
  c). 
  Setae 
  usually 
  compound 
  spinigers 
  and 
  falcigers 
  

   (fig. 
  30, 
  d-g). 
  Pair 
  of 
  anal 
  cirri. 
  Proboscis 
  eversible, 
  with 
  pair 
  of 
  

   terminal, 
  horny, 
  falcate 
  jaws 
  and 
  usually 
  with 
  horny 
  denticles 
  or 
  

   paragnaths 
  arranged 
  in 
  eight 
  groups 
  on 
  two 
  rings, 
  a 
  basal 
  or 
  oral 
  

   ring 
  and 
  a 
  distal 
  or 
  maxillary 
  ring 
  (fig. 
  30, 
  h, 
  i). 
  At 
  maturity 
  usually 
  

   with 
  a 
  pelagic 
  epitokous 
  or 
  heteronereis 
  stage. 
  

  

  Represented 
  by 
  a 
  single 
  genus 
  and 
  two 
  species. 
  

  

  Genus 
  Nereis 
  Cuvier, 
  1817 
  

  

  Subgenus 
  Nereis 
  Linne, 
  1758 
  

  

  Both 
  species 
  have 
  the 
  body 
  smooth, 
  elongate, 
  cylindrical, 
  at- 
  

   tenuated 
  posteriorly, 
  with 
  numerous 
  segments. 
  Prostomium 
  of 
  the 
  

   typical 
  nereid 
  form. 
  Tentacular 
  segment 
  achaetous, 
  over 
  twice 
  the 
  

   length 
  of 
  the 
  following 
  segments; 
  tentacular 
  cirri 
  short, 
  fairly 
  uniform 
  

   in 
  length, 
  the 
  upper 
  one 
  only 
  slightly 
  longer 
  than 
  the 
  others 
  (may 
  

   reach 
  setiger 
  2). 
  Parapodia 
  biramous, 
  with 
  two 
  subequal 
  noto- 
  

   podial 
  ligules 
  (remaining 
  so 
  throughout 
  the 
  body, 
  the 
  upper 
  one 
  not 
  

   getting 
  larger 
  or 
  longer 
  than 
  the 
  lower 
  one), 
  a 
  single 
  neuropodial 
  

   ligule 
  ventral 
  to 
  the 
  conical 
  setigerous 
  neuropodial 
  lobe 
  (fig. 
  30, 
  h, 
  c). 
  

   Notosetae 
  homogomph 
  spinigers 
  (fig. 
  30, 
  g); 
  in 
  more 
  posterior 
  seg- 
  

   ments 
  with 
  some 
  homogomph 
  falcigers 
  with 
  blunt 
  asymmetrical 
  

   reduced 
  appendages 
  (fig. 
  30, 
  e). 
  Neurosetae 
  homogomph 
  and 
  

  

  