﻿NO. 
  1959. 
  8TPUNCULIDS 
  OF 
  EASTERN 
  NORTH 
  AMERICA— 
  GEROULD. 
  411 
  

  

  Station 
  998, 
  lat. 
  39° 
  43' 
  N.; 
  long. 
  71° 
  32' 
  W.; 
  302 
  fathoms, 
  green 
  

   mud. 
  

  

  Station 
  1025, 
  lat. 
  39° 
  49' 
  N.; 
  long. 
  71° 
  25' 
  W.; 
  216 
  fathoms, 
  green 
  

   mud. 
  

  

  Station 
  1038, 
  lat. 
  39° 
  58' 
  N.; 
  long. 
  70° 
  06' 
  W.; 
  146 
  fathoms, 
  sand 
  

   and 
  shells. 
  

  

  Station 
  2177, 
  lat. 
  39° 
  33' 
  40" 
  N.; 
  long. 
  72° 
  08' 
  45" 
  W.; 
  87 
  fathoms, 
  

   green 
  mud 
  and 
  sand. 
  

  

  Stations 
  89-91B, 
  lat. 
  42° 
  05' 
  N.; 
  long. 
  67° 
  49' 
  W.; 
  110 
  fathoms, 
  soft 
  

   mud 
  and 
  sand. 
  

  

  This 
  variety 
  was 
  found 
  on 
  both 
  sides 
  of 
  the 
  100-fathom 
  line 
  south 
  

   of 
  Marthas 
  Vineyard 
  near 
  the 
  fortieth 
  parallel, 
  and 
  at 
  a 
  similar 
  

   depth 
  off 
  the 
  northwest 
  border 
  of 
  St. 
  Georges 
  Bank 
  east 
  of 
  Cape 
  

   Cod 
  (stations 
  89-91B). 
  

  

  Specunens 
  from 
  station 
  921 
  are 
  incased 
  in 
  cast 
  shells 
  of 
  Protula; 
  

   that 
  from 
  2177 
  is 
  accompanied 
  by 
  a 
  tube 
  probably 
  of 
  a 
  sabellid 
  

   (elastic 
  membrane 
  covered 
  with 
  grains 
  of 
  sand); 
  those 
  from 
  89-91B 
  

   are 
  in 
  Dentalium 
  shells 
  and 
  one 
  individual 
  in 
  the 
  shell 
  of 
  a 
  small 
  

   gasteropod. 
  Two 
  small 
  specimens 
  of 
  the 
  typical 
  form 
  were 
  taken 
  at 
  

   the 
  last-mentioned 
  station. 
  

  

  Without 
  doubt 
  the 
  external 
  peculiarities 
  of 
  tliis 
  variety 
  are 
  pro- 
  

   duced 
  by 
  the 
  character 
  of 
  the 
  tubes 
  in 
  which 
  the 
  individuals 
  live; 
  

   the 
  smooth, 
  elongated 
  body, 
  the 
  shapes 
  of 
  the 
  holdfasts, 
  the 
  length 
  of 
  

   the 
  introvert, 
  and 
  even 
  the 
  form 
  of 
  the 
  nephridium 
  are 
  clearly 
  

   adaptations 
  to 
  the 
  life 
  within 
  the 
  slender, 
  smooth-walled 
  tube 
  of 
  

   Protula 
  or 
  shell 
  of 
  Dentalium. 
  Moreover, 
  it 
  seems 
  probable 
  that 
  

   these 
  characteristics 
  are 
  determined 
  anew 
  during 
  the 
  lifetime 
  of 
  each 
  

   individual 
  by 
  the 
  direct 
  action 
  of 
  the 
  tube 
  or 
  shell 
  upon 
  its 
  occupant. 
  

  

  Characteristics. 
  — 
  The 
  body 
  and 
  introvert 
  are 
  long 
  and 
  slender, 
  the 
  

   introvert 
  of 
  about 
  the 
  same 
  length 
  as 
  the 
  trunk. 
  The 
  trunk 
  is 
  nearly 
  

   smooth, 
  except 
  near 
  the 
  anterior 
  extremity. 
  Holdfasts 
  lie 
  in 
  a 
  broad 
  

   zone, 
  which 
  in 
  front 
  extends 
  to 
  the 
  middle 
  of 
  the 
  trunk. 
  It 
  inhabits 
  

   straight 
  tubes 
  or 
  shells. 
  The 
  ventral 
  muscles 
  when 
  expanded 
  show 
  

   two 
  long, 
  slender 
  roots. 
  The 
  attachment 
  of 
  the 
  dorsal 
  muscle 
  

   posteriorly 
  is 
  thicker 
  laterally 
  than 
  in 
  the 
  middle, 
  where 
  it 
  shows 
  a 
  

   tendency 
  to 
  break 
  apart 
  into 
  several 
  distinct 
  strands. 
  The 
  nephro- 
  

   stome 
  is 
  crescentic 
  with 
  a 
  slender 
  neck. 
  

  

  The 
  introvert, 
  judging 
  from 
  the 
  examination 
  of 
  a 
  few 
  specimens 
  

   which 
  are 
  mostly 
  somewhat 
  contracted, 
  is 
  of 
  about 
  the 
  same 
  length 
  as 
  

   the 
  trunk, 
  slender 
  and 
  smooth, 
  except 
  at 
  the 
  base 
  where 
  it 
  is 
  covered 
  

   with 
  small 
  papillae. 
  The 
  trunk 
  at 
  its 
  junction 
  with 
  the 
  introvert 
  is 
  

   covered 
  with 
  very 
  prominent 
  papillae, 
  in 
  a 
  narrow 
  zone 
  behind 
  which 
  

   the 
  papillae 
  decrease 
  rapidly 
  in 
  size. 
  The 
  posterior 
  half 
  of 
  the 
  trunk 
  

   is 
  smooth, 
  the 
  papillae 
  being 
  very 
  minute. 
  The 
  holdfasts 
  extend 
  

   forward 
  to 
  about 
  the 
  middle 
  of 
  the 
  trunk 
  and 
  in 
  some 
  individuals 
  are 
  

  

  