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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  los 
  

  

  Description. 
  — 
  Up 
  to 
  31 
  mm. 
  long, 
  14 
  mm. 
  wide. 
  Body 
  variable 
  in 
  

   shape; 
  may 
  be 
  inflated 
  at 
  both 
  ends, 
  anterior 
  region 
  may 
  be 
  retracted 
  

   into 
  more 
  posterior 
  segments. 
  Integument 
  densely 
  pilose, 
  covered 
  

   with 
  fine 
  filiform 
  papillae. 
  Anterior 
  region 
  of 
  seven 
  segments; 
  

   segments 
  1 
  and 
  5-7 
  achaetous; 
  segments 
  2-4 
  each 
  with 
  lateral 
  semi- 
  

   circular 
  row 
  of 
  strong, 
  short, 
  yellow 
  setae 
  which 
  are 
  arched, 
  pointed 
  

   to 
  blunt 
  (worn 
  down), 
  diminishing 
  in 
  size 
  toward 
  ventral 
  side; 
  pair 
  

   of 
  long 
  genital 
  papillae 
  on 
  segment 
  7. 
  Middle 
  region 
  of 
  six 
  segments, 
  

   weU 
  defined 
  except 
  for 
  narrow 
  midventral 
  strip, 
  with 
  bundles 
  of 
  capil- 
  

   lary 
  setae 
  embedded 
  in 
  body 
  wall. 
  Posterior 
  region 
  with 
  five 
  or 
  more 
  

   segments, 
  with 
  ventral 
  horny 
  trapezoidal 
  plates 
  showing 
  concentric 
  

   and 
  radiating 
  striae, 
  each 
  plate 
  with 
  16 
  radiating 
  bundles 
  of 
  stiff 
  

   setae, 
  9 
  on 
  lateral 
  and 
  7 
  on 
  posterior 
  borders. 
  Anal 
  filaments 
  or 
  

   branchiae 
  very 
  numerous, 
  long, 
  filiform, 
  sometimes 
  spiralled. 
  Colok 
  : 
  

   In 
  alcohol: 
  Without 
  color 
  or 
  brownish, 
  with 
  rusty-red 
  ventral 
  shield. 
  

  

  New 
  records. 
  — 
  Arctic 
  Alaska: 
  Off 
  Point 
  Barrow 
  base, 
  up 
  to 
  5 
  

   miles 
  from 
  shore, 
  1.7-24.7 
  fms., 
  on 
  bottoms 
  of 
  mud 
  and 
  gravel 
  with 
  

   mud 
  (3 
  stations, 
  5 
  specimens). 
  Bering 
  Sea: 
  63°37' 
  N., 
  165°19' 
  W., 
  

   12 
  fms., 
  Stoney, 
  1884; 
  off 
  mouth 
  Yukon 
  Eiver, 
  3 
  fms., 
  E. 
  W. 
  Nelson, 
  

   1877. 
  Alaska: 
  Iluiliuk 
  Harbor, 
  Unalaska, 
  Dall, 
  1871; 
  Albatross 
  

   Sta. 
  3340, 
  55°26' 
  N., 
  155°26' 
  W., 
  695 
  fms., 
  and 
  Sta. 
  3330, 
  54° 
  N., 
  

   166°53' 
  W., 
  351 
  fms., 
  1890. 
  Chiachi 
  Islands, 
  20 
  fms., 
  1874; 
  off 
  

   Round 
  Island, 
  Coal 
  Harbor, 
  Unga 
  Island, 
  6-8 
  fms., 
  1872; 
  Eastern 
  

   Harbor, 
  Sitka, 
  15 
  fms., 
  gravelly-mud, 
  1874; 
  all 
  collected 
  by 
  Dall. 
  

   West 
  Coast 
  North 
  America: 
  Washington 
  and 
  Puget 
  Sounds, 
  

   10-111 
  fms., 
  mud, 
  Pettibone. 
  East 
  Coast 
  North 
  America: 
  Nova 
  

   Scotia, 
  Maine, 
  Massachusetts, 
  5-102 
  fms., 
  U. 
  S. 
  Fish 
  Commission. 
  

  

  Distribution. 
  — 
  Scattered 
  records 
  in 
  the 
  Arctic 
  : 
  Siberian 
  and 
  Alaskan 
  

   Arctic, 
  Greenland. 
  Also 
  Iceland 
  to 
  English 
  Channel, 
  Mediterranean, 
  

   Adriatic, 
  Gulf 
  of 
  Oman, 
  Persian 
  Gulf; 
  Nova 
  Scotia 
  to 
  Massachusetts; 
  

   Bering 
  Sea 
  to 
  Panamd; 
  north 
  Japan 
  Sea 
  to 
  Japan, 
  China. 
  Southern 
  

   latitudes: 
  South 
  Shetlands, 
  Palmer 
  Archipelago, 
  South 
  Orkneys, 
  

   South 
  Georgia, 
  west 
  Africa, 
  Indian 
  Ocean, 
  Australia, 
  New 
  Zealand. 
  

   In 
  1.7-766 
  fathoms. 
  

  

  Family 
  Pectinariidae 
  (Amphictenidae) 
  

  

  Body 
  short, 
  conical, 
  with 
  segments 
  few 
  in 
  number. 
  Prostomium 
  

   indistinct, 
  fused 
  with 
  buccal 
  segment 
  forming 
  a 
  truncate 
  anterior 
  end 
  

   provided 
  with 
  two 
  bundles 
  of 
  paleae 
  (}&Tge, 
  flattened, 
  golden 
  setae) 
  

   in 
  a 
  horizontal 
  row 
  directed 
  obliquely 
  anteriorly, 
  forming 
  an 
  operculum 
  

   for 
  the 
  tube 
  or 
  as 
  a 
  fork 
  for 
  digging 
  in 
  sand 
  or 
  mud 
  ; 
  ventral 
  to 
  paleae, 
  

   an 
  antennular 
  or 
  tentacular 
  membrane 
  bordered 
  or 
  not 
  with 
  short 
  to 
  

   long 
  filiform 
  papillae, 
  surrounding 
  numerous 
  prehensile 
  oral 
  tentacles 
  

  

  