﻿No. 
  1959. 
  SIPUNCULID8 
  OF 
  EASTERN 
  NORTH 
  AMERICA— 
  GEROULD. 
  415 
  

  

  posterior 
  end 
  of 
  the 
  body 
  equal 
  to 
  about 
  one-fourth 
  the 
  length 
  of 
  the 
  

   trunk. 
  The 
  ventral 
  muscle 
  is 
  slender 
  and 
  inconspicuous. 
  It 
  is 
  

   attached 
  by 
  two 
  cylindrical 
  roots, 
  one 
  on 
  each 
  side 
  of 
  the 
  posterior 
  

   end 
  of 
  the 
  nerve 
  cord. 
  

  

  The 
  long, 
  slender 
  esophagus 
  joins 
  a 
  wide 
  intestine 
  of 
  about 
  six 
  

   loops 
  extending 
  backward 
  and 
  forward. 
  A 
  prominent 
  strand 
  of 
  

   muscle 
  fibers 
  extends 
  from 
  the 
  anterior 
  intestinal 
  loops 
  into 
  the 
  

   region 
  of 
  the 
  introvert, 
  and 
  less 
  conspicuous 
  strands 
  elsewhere 
  hold 
  

   the 
  intestine 
  to 
  the 
  body 
  wall. 
  The 
  single 
  (right) 
  nephridium 
  is 
  

   largo, 
  and 
  has 
  a 
  prominent 
  nephrostome. 
  The 
  nerve 
  cord 
  is 
  a 
  rela- 
  

   tively 
  wide 
  band. 
  

  

  MODIFICATIONS 
  IN 
  THE 
  SOUTH. 
  

  

  The 
  number 
  of 
  local 
  varieties 
  of 
  this 
  spscies 
  probably 
  will 
  be 
  

   found 
  to 
  be 
  even 
  greater 
  when 
  the 
  southern 
  part 
  of 
  its 
  range 
  is 
  more 
  

   thoroughly 
  explored. 
  A 
  specimen 
  from 
  off 
  Cape 
  Charles, 
  Virginia 
  

   (station 
  2003, 
  641 
  fathoms), 
  is 
  typical 
  in 
  internal 
  features 
  in 
  all 
  

   respects, 
  but 
  externally 
  it 
  is 
  remarkable 
  for 
  its 
  peculiar 
  dark 
  greenish- 
  

   gray 
  color. 
  It 
  has 
  a 
  thick 
  integument 
  covered 
  with 
  prominent 
  

   papillse, 
  and 
  an 
  unusually 
  distinctly 
  marked 
  anus. 
  Except 
  for 
  the 
  

   peculiar 
  greenish-gray 
  hue 
  it 
  resembles 
  the 
  variety 
  tuhicola 
  from 
  the 
  

   region 
  of 
  Cape 
  Ann. 
  Its 
  shape 
  indicates 
  that 
  it 
  lived 
  in 
  a 
  tube 
  of 
  

   cement. 
  

  

  Other 
  specimens 
  from 
  the 
  same 
  southern 
  region, 
  that 
  is, 
  from 
  the 
  

   fortieth 
  parallel 
  southward 
  to 
  Cape 
  Hatteras, 
  have 
  a 
  noteworthy 
  

   internal 
  peculiarity, 
  namely, 
  the 
  posterior 
  attachment 
  of 
  the 
  ventral 
  

   retractor 
  does 
  not 
  lie 
  behind 
  the 
  posterior 
  end 
  of 
  the 
  nerve 
  cord, 
  as 
  

   in 
  other 
  varieties 
  of 
  this 
  species, 
  but 
  beside 
  it 
  to 
  the 
  left, 
  thus 
  show- 
  

   ing 
  a 
  more 
  prominent 
  asymmetry 
  in 
  the 
  internal 
  organization 
  than 
  

   in 
  any 
  other 
  variety 
  of 
  the 
  species. 
  

  

  Externally 
  these 
  specimens 
  from 
  different 
  southern 
  localities 
  differ 
  

   much. 
  Those 
  from 
  the 
  shells 
  of 
  Dentalium 
  solidum 
  (station 
  273.3, 
  

   944 
  fathoms, 
  off 
  Cape 
  Charles; 
  station 
  2207, 
  1,071 
  fathoms, 
  just 
  

   south 
  of 
  the 
  fortieth 
  parallel) 
  have 
  a 
  thin, 
  smooth 
  skin 
  of 
  orange 
  

   brown 
  color. 
  Those 
  from 
  the 
  gasteropod 
  SijyJio 
  pygmseus 
  (station 
  

   898, 
  300 
  fathoms, 
  off 
  Norfolk, 
  Virginia) 
  have 
  a 
  smooth, 
  wliitish 
  skin 
  

   and 
  an 
  external 
  appearance 
  like 
  those 
  described 
  as 
  the 
  variety 
  

   alha. 
  

  

  The 
  crowding 
  aside 
  of 
  the 
  extremity 
  of 
  the 
  retractor 
  in 
  reference 
  to 
  

   that 
  of 
  the 
  nerve 
  cord 
  has 
  made 
  a 
  still 
  further 
  modification 
  in 
  certain 
  

   individuals 
  inhabiting 
  the 
  shells 
  of 
  Dentalium 
  solidum, 
  in 
  that 
  the 
  

   attachment 
  of 
  the 
  ventral 
  retractor 
  is 
  undivided; 
  this, 
  however, 
  is 
  

   not 
  true 
  of 
  the 
  specimens 
  from 
  the 
  shells 
  of 
  Sipho 
  pygmseus. 
  Selenka 
  

   (1883) 
  likewise 
  found 
  in 
  a 
  specimen 
  from 
  the 
  West 
  Indies, 
  which 
  he 
  

  

  