﻿390 
  

  

  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  

  

  vert 
  and 
  at 
  the 
  posterior 
  end 
  of 
  the 
  trunk 
  are 
  finger-shaped, 
  or 
  bkmtly 
  

   conical, 
  and 
  attached 
  to 
  the 
  body 
  by 
  a 
  small 
  neck. 
  On 
  the 
  intro- 
  

   vert 
  of 
  a 
  large 
  individual 
  they 
  measure 
  0.08 
  mm. 
  or 
  0.09 
  mm. 
  in 
  

   length 
  and 
  0.033 
  mm. 
  to 
  0.038 
  mm. 
  in 
  breadth, 
  but 
  on 
  another 
  speci- 
  

   men 
  they 
  are 
  from 
  0.04 
  mm. 
  to 
  0.05 
  mm. 
  long 
  and 
  about 
  0.03 
  mm. 
  in 
  

   thiclcness. 
  In 
  the 
  middle 
  of 
  the 
  trunk 
  the 
  larger 
  papillae 
  are 
  ovate 
  

   and 
  fungiform, 
  about 
  0.04 
  mm. 
  in 
  diameter. 
  Smaller, 
  undeveloped 
  

   papillae 
  are 
  interspersed 
  among 
  the 
  others. 
  

  

  The 
  two 
  (ventral) 
  retractor 
  muscles 
  (fig. 
  2) 
  arise 
  from 
  the 
  body 
  

   wall 
  in 
  the 
  adidt 
  slightly 
  in 
  front 
  of 
  the 
  middle 
  of 
  the 
  trunk. 
  In 
  a 
  

  

  very 
  young 
  indi- 
  

   vidual 
  (7 
  mm. 
  -8 
  

   mm. 
  ii^ 
  length) 
  

   they 
  were 
  found 
  

   to 
  arise 
  at 
  the 
  

   posterior 
  end 
  of 
  

   the 
  second 
  third. 
  

   The 
  relative 
  posi- 
  

   tion 
  of 
  the 
  attach- 
  

   ments 
  of 
  these 
  

   muscles 
  evidently 
  

   shifts 
  forward 
  in 
  

   this 
  form, 
  as 
  in 
  

   other 
  sipunculids, 
  

   during 
  the 
  post- 
  

   larval 
  life, 
  owing 
  

   to 
  excessive 
  

   gi-owthofthebody 
  

   wall 
  at 
  the 
  poste- 
  

   rior 
  pole. 
  (See 
  

   Gerould, 
  1906, 
  p. 
  

   119.) 
  

   The 
  pairof 
  large 
  

  

  Fig. 
  2.— 
  Dissection 
  of 
  Phascolosoma 
  VERRaLn. 
  x 
  9. 
  an, 
  anus; 
  go, 
  nepnriQia 
  are 
  Slt- 
  

  

  REPRODUCTIVE 
  ORGANS; 
  7?i.rtr, 
  RETRACTOR 
  MUSCLE; 
  Ueph, 
  NEPHRIDIUM; 
  Viatcd 
  UCarlV 
  OD" 
  

   OC, 
  PIGMENTED 
  eye; 
  t&. 
  PoZ, 
  POLIANTUBin-E. 
  . 
  .i 
  

  

  posite 
  the 
  anus, 
  

   but 
  slightly 
  in 
  front 
  of 
  it. 
  A 
  prominent 
  ciliated 
  nephrostome 
  opens 
  

   into 
  the 
  ventral 
  side 
  of 
  the 
  base 
  of 
  the 
  nephridium. 
  Its 
  circular 
  ori- 
  

   fice 
  communicates 
  with 
  a 
  narrower 
  passage 
  which 
  runs 
  backward 
  

   close 
  to 
  the 
  ventral 
  wall 
  of 
  the 
  nephridium 
  and 
  parallel 
  to 
  the 
  latter 
  

   into 
  the 
  cavity 
  of 
  the 
  nephridium, 
  from 
  which 
  a 
  septum 
  partially 
  

   separates 
  it. 
  The 
  length 
  of 
  the 
  passage 
  is 
  three 
  or 
  four 
  times 
  the 
  

   \vidth 
  of 
  the 
  orifice. 
  

  

  The 
  supraesophagal 
  ganglion 
  of 
  the 
  adult 
  is 
  oval, 
  or 
  spindle- 
  

   shaped, 
  with 
  its 
  chief 
  axis 
  transverse 
  to 
  the 
  length 
  of 
  the 
  body. 
  A 
  

  

  