﻿MARINE 
  POLYCHAETE 
  WORMS 
  — 
  PETTIBONE 
  343 
  

  

  on 
  smooth 
  peduncle. 
  Collarette 
  large, 
  widely 
  separated 
  dorsally, 
  

   entire 
  laterally 
  and 
  ventraUy. 
  Three 
  thoracic 
  setigers, 
  the 
  first 
  

   setiger 
  with 
  only 
  dorsal 
  setae 
  (collar 
  setae) 
  and 
  the 
  next 
  two 
  with 
  

   ventral 
  tori 
  in 
  addition 
  to 
  dorsal 
  setae. 
  With 
  well-developed 
  thoracic 
  

   membrane. 
  A 
  long 
  achaetous 
  region 
  between 
  thorax 
  and 
  abdomen 
  

   (may 
  be 
  crowded 
  with 
  ova; 
  spermatozoa 
  develop 
  in 
  more 
  posterior 
  

   segments 
  ; 
  hermaphroditic) 
  . 
  About 
  20 
  abdominal 
  setigers. 
  Pygidium 
  

   with 
  two 
  rounded 
  lobes. 
  Colorless 
  in 
  alcohol. 
  Tube 
  small 
  (1-3 
  mm. 
  

   in 
  diameter), 
  closely 
  coiled, 
  white, 
  opaque, 
  fixed 
  to 
  hydroids, 
  bryozoa, 
  

   algae, 
  carapaces 
  of 
  crustaceans, 
  spines 
  of 
  tunicates, 
  stones, 
  etc. 
  

  

  Key 
  to 
  the 
  species 
  of 
  Spirorbis 
  from 
  Point 
  Barrow 
  

  

  1. 
  Tube 
  with 
  sinistral 
  (counterclockwise) 
  spiral 
  coiling 
  (with 
  mouth 
  of 
  tube 
  

   facing 
  observer, 
  the 
  opening 
  is 
  on 
  the 
  left; 
  fig. 
  39, 
  r). 
  Eggs 
  incubated 
  in 
  

   operculum. 
  Collar 
  setae 
  with 
  well-developed 
  basal 
  crenulate 
  wings 
  (fig. 
  

   39, 
  t) 
  S. 
  (Laeospira) 
  granulatus 
  

  

  Tube 
  with 
  dextral 
  (clockwise) 
  spiral 
  coiling 
  (fig. 
  39, 
  v). 
  Eggs 
  incubated 
  in 
  

   tube. 
  Collar 
  setae 
  without 
  crenulate 
  wings 
  (fig. 
  39, 
  x) 
  . 
  

  

  S. 
  (Dexiospira) 
  spirillum 
  

  

  Spirorbis 
  (Laeospira) 
  granulatus 
  (Linn^, 
  1767) 
  

  

  Figure 
  39, 
  r-t 
  

  

  Serpula 
  granulata 
  Linn^, 
  1767, 
  p. 
  1266. 
  

  

  Spirorbis 
  quadrangular 
  is 
  Stimpson, 
  1854, 
  p. 
  29. 
  — 
  Moore, 
  1908, 
  p. 
  362. 
  — 
  Hartman, 
  

   1944a, 
  pp. 
  336, 
  343. 
  

  

  Spirorbis 
  (Laeospira) 
  granulatus 
  Borg, 
  1917, 
  p. 
  28, 
  figs. 
  14-16. 
  — 
  Fauvel, 
  1927, 
  p. 
  

   403, 
  fig. 
  137, 
  q-u.— 
  Augener, 
  1928, 
  p. 
  815.— 
  Annenkova, 
  1937, 
  p. 
  198; 
  1938, 
  

   p. 
  219.— 
  Berkeley 
  and 
  Berkeley, 
  1943, 
  p. 
  130; 
  1952, 
  p. 
  137, 
  figs. 
  286, 
  287.— 
  

   Gorbunov, 
  1946, 
  p. 
  39.— 
  ? 
  Thorson, 
  1946, 
  p. 
  139, 
  fig. 
  80.— 
  Zatsepin, 
  1948, 
  

   p. 
  166.— 
  Wesenberg-Lund, 
  1950a, 
  p. 
  63; 
  1950b, 
  p. 
  141; 
  1951, 
  p. 
  135. 
  

  

  Description. 
  — 
  Tube 
  1-2 
  mm. 
  in 
  diameter, 
  dull 
  chalky 
  white, 
  opaque, 
  

   somewhat 
  rugose 
  and 
  variable 
  with 
  two 
  longitudinal 
  ridges, 
  one 
  on 
  

   each 
  side 
  (the 
  opening 
  almost 
  quadrangular), 
  or 
  with 
  three 
  more 
  or 
  

   less 
  distinct 
  longitudinal 
  keels, 
  or 
  without 
  crests; 
  the 
  tube 
  is 
  coiled 
  

   sinistrally, 
  up 
  to 
  two 
  coils, 
  flatly 
  on 
  smooth 
  surfaces 
  or 
  somewhat 
  

   open 
  when 
  on 
  rough 
  surfaces; 
  it 
  may 
  encircle 
  a 
  strand 
  of 
  hydroid 
  and 
  

   the 
  free 
  end 
  may 
  extend 
  upward. 
  Operculum 
  with 
  terminal 
  plate 
  

   strongly 
  convex, 
  calcareous, 
  with 
  long, 
  cylindrical 
  projection 
  (short 
  

   on 
  one 
  side, 
  longer 
  on 
  opposite 
  side), 
  with 
  large 
  brood 
  pouch 
  for 
  

   incubating 
  eggs 
  (eggs 
  in 
  operculum. 
  Point 
  Barrow, 
  August 
  17, 
  1949, 
  

   and 
  February 
  18, 
  1950). 
  Collar 
  setae 
  with 
  blades 
  finely 
  serrated, 
  

   with 
  well-developed 
  crenulate 
  wing 
  at 
  base. 
  

  

  New 
  records. 
  — 
  Arctic 
  Alaska: 
  Off 
  Point 
  Barrow 
  base, 
  up 
  to 
  12.1 
  

   miles 
  from 
  shore, 
  27-123.5 
  fms., 
  on 
  bottoms 
  of 
  mass 
  of 
  worm 
  tubes. 
  

  

  