﻿I56 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  porum 
  has 
  afforded 
  the 
  material 
  for 
  most 
  of 
  the 
  illustrations 
  

   here 
  given. 
  Of 
  this 
  very 
  common 
  species 
  in 
  the 
  calcareous 
  shales 
  of 
  

   the 
  Hamilton 
  I 
  have 
  been 
  able 
  to 
  critically 
  examine 
  several 
  hun- 
  

   dred 
  individuals 
  and 
  it 
  is 
  safe 
  to 
  say 
  that 
  the 
  worm 
  is 
  present 
  in 
  

   the 
  majority 
  of 
  examples. 
  It 
  is 
  easy 
  to 
  determine 
  its 
  presence 
  on 
  

   inspection 
  of 
  the 
  tentacular 
  surface 
  of 
  the 
  coral 
  by 
  the 
  contrast 
  

   between 
  its 
  round 
  tubes 
  and 
  the 
  angular 
  coral 
  cells. 
  All 
  the 
  speci- 
  

   mens 
  here 
  figured 
  to 
  show 
  the 
  convolutions 
  of 
  the 
  worm 
  have 
  

   been 
  drawn 
  from 
  actual 
  preparations. 
  

  

  The 
  history 
  of 
  the 
  combination 
  in 
  P. 
  s 
  t 
  y 
  1 
  o 
  p 
  o 
  r 
  u 
  m 
  is 
  as 
  

   follows: 
  At 
  the 
  close 
  of 
  the 
  free-swimming 
  larval 
  stage 
  the 
  coral, 
  

   in 
  fully 
  eight 
  cases 
  out 
  of 
  ten, 
  selected 
  and 
  attached 
  itself 
  to 
  a 
  dead 
  

   or 
  living 
  shell 
  of 
  the 
  gastropod 
  Loxonema 
  hamiltoniae.' 
  

   Directly 
  upon 
  fixation 
  or 
  even 
  actually 
  contemporaneous 
  with 
  it 
  

   was 
  the 
  attachment 
  of 
  the 
  larval 
  worm 
  upon 
  the 
  incipient 
  coral 
  or 
  

   alongside 
  it. 
  In 
  many 
  cases, 
  such 
  as 
  that 
  illustrated 
  in 
  plate 
  4, 
  figure 
  3, 
  

   the 
  worm 
  tube 
  is 
  directly 
  fixed 
  to 
  the 
  gastropod; 
  again 
  it 
  may 
  

   be 
  free 
  of 
  the 
  gastropod, 
  and 
  separated 
  from 
  it 
  by 
  the 
  thick- 
  

   ened 
  basal 
  theca 
  [see 
  pi. 
  4, 
  fig. 
  1, 
  2]. 
  With 
  the 
  multiplication 
  of 
  

   cell 
  growth 
  and 
  the 
  upward 
  trend 
  of 
  the 
  coral, 
  the 
  worm 
  began 
  

   its 
  convoluted 
  growth, 
  its 
  tube 
  growing 
  as 
  much 
  at 
  one 
  end 
  

   as 
  at 
  the 
  other. 
  Some 
  of 
  the 
  existing 
  serpulid 
  worms 
  have 
  

   their 
  eyes 
  on 
  the 
  hinder 
  end 
  of 
  the 
  body 
  at 
  the 
  tentacular 
  

   surface; 
  it 
  is 
  fair 
  to 
  presume 
  that 
  at 
  this 
  early 
  period 
  this 
  

   advanced 
  stage 
  of 
  degeneracy 
  had 
  not 
  been 
  reached 
  and 
  the 
  

   tube 
  was 
  thus 
  kept 
  open 
  at 
  both 
  ends. 
  In 
  view 
  of 
  the 
  regularity 
  

   of 
  coiling 
  shown 
  in 
  some 
  of 
  the 
  commensal 
  worm 
  tubes 
  it 
  is 
  

   interesting 
  to 
  notice 
  that 
  in 
  this 
  case 
  the 
  worm 
  after 
  making 
  

   a 
  start, 
  gets 
  its 
  double 
  coil 
  into 
  parallelism 
  for 
  a 
  half 
  to 
  an 
  entire 
  

   turn 
  and 
  then 
  each 
  arm 
  starts 
  off 
  into 
  a 
  direct 
  course 
  follow- 
  

   ing 
  the 
  radial 
  path 
  of 
  the 
  coral 
  cells. 
  These 
  branches 
  often 
  pass 
  

   in 
  and 
  out 
  between 
  the 
  cells, 
  keeping 
  their 
  extremities 
  always 
  at 
  

   the 
  tentacular 
  surface 
  and 
  very 
  seldom 
  is 
  there 
  evidence 
  of 
  the 
  

   worm 
  encroaching 
  on 
  the 
  polypite 
  cells. 
  Still 
  this 
  may 
  occur 
  and 
  

   the 
  worm 
  tube 
  occasionally 
  becomes 
  encased 
  by 
  a 
  young 
  polypite 
  

   and 
  holds 
  a 
  position 
  in 
  the 
  center 
  of 
  the 
  cell 
  [pi. 
  4, 
  fig. 
  4]. 
  

  

  There 
  may 
  be 
  other 
  worms 
  encased 
  in 
  the 
  thickened 
  base 
  of 
  this 
  

   coral 
  as 
  shown 
  in 
  figures 
  1, 
  2, 
  plate 
  4, 
  but 
  it 
  is 
  not 
  yet 
  clear 
  where 
  

   their 
  apertures 
  lie 
  as 
  I 
  have 
  never 
  seen 
  but 
  two 
  annelid 
  openings 
  at 
  

   the 
  surface 
  of 
  the 
  adult 
  coral. 
  It 
  is 
  quite 
  possible 
  that 
  originally 
  

   opening 
  on 
  the 
  tentacular 
  surface 
  at 
  an 
  early 
  stage 
  of 
  coral 
  growth 
  

  

  