﻿82 
  E. 
  J. 
  ALLIEN. 
  

  

  record 
  of 
  the 
  fact 
  has 
  ever 
  been 
  published. 
  The 
  larva 
  is 
  

   probably 
  frequent 
  in 
  plankton 
  taken 
  all 
  round 
  our 
  coasts^ 
  and 
  

   its 
  appearance 
  will 
  be 
  well 
  known 
  to 
  workers, 
  as 
  it 
  renders 
  

   itself 
  conspicuous 
  by 
  its 
  rapid, 
  wriggling 
  motion 
  and 
  by 
  the 
  

   row 
  of 
  pigment 
  spots 
  (large 
  branching 
  chromatophores) 
  

   between 
  the 
  parapodial 
  cirri 
  along 
  each 
  side 
  of 
  the 
  body. 
  

  

  On 
  April 
  lOth, 
  1902, 
  the 
  Laboratory 
  fisherman 
  brought 
  in 
  

   two 
  specimens 
  of 
  a 
  worm 
  which 
  he 
  recognised 
  as 
  unfamiliar. 
  

   These 
  specimens 
  he 
  had 
  obtained 
  when 
  digging 
  on 
  a 
  patch 
  of 
  

   sand 
  exposed 
  at 
  low 
  spring 
  tide 
  immediately 
  south 
  of 
  the 
  

   coastguard 
  station 
  at 
  Mount 
  Batten, 
  on 
  the 
  eastern 
  side 
  of 
  

   Plymouth 
  Sound. 
  The 
  worm 
  has 
  proved 
  to 
  be 
  the 
  adult 
  

   Poecilochsetus, 
  which 
  forms 
  the 
  subject 
  of 
  the 
  present 
  

   paper. 
  

  

  Since 
  that 
  time 
  I 
  have 
  always 
  been 
  able 
  to 
  obtain 
  a 
  few 
  

   specimens 
  whenever 
  the 
  tide 
  has 
  allowed 
  of 
  digging 
  on 
  this 
  

   particular 
  patch 
  of 
  sand. 
  Unfortunately 
  the 
  sand 
  is 
  only 
  

   uncovered 
  at 
  the 
  lowest 
  spi'ing 
  tides, 
  and 
  it 
  is 
  only 
  on 
  com- 
  

   paratively 
  few 
  days 
  during 
  the 
  year 
  that 
  the 
  worm 
  can 
  be 
  

   obtained. 
  During 
  the 
  hour, 
  or 
  hour 
  and 
  a 
  half, 
  that 
  the 
  sand 
  

   may 
  be 
  uncovered 
  at 
  any 
  tide 
  from 
  six 
  to 
  eight 
  head 
  ends 
  of 
  

   the 
  worm 
  have 
  been 
  collected. 
  As 
  the 
  animals 
  break 
  very 
  

   readily 
  when 
  disturbed, 
  complete 
  specimens 
  are 
  difhcult 
  to 
  

   procure, 
  and 
  only 
  two 
  such 
  have 
  as 
  yet 
  been 
  obtained. 
  The 
  

   local 
  area 
  of 
  distribution 
  of 
  Pteciloch 
  tetus 
  is 
  very 
  restricted. 
  

   The 
  portion 
  of 
  shore 
  where 
  it 
  is 
  known 
  to 
  live 
  consists 
  of 
  

   patches 
  of 
  sand 
  covered 
  with 
  zostera, 
  with 
  intermediate 
  

   patches 
  of 
  a 
  somewhat 
  different 
  texture 
  on 
  which 
  no 
  zostera 
  

   grows. 
  The 
  worm 
  appears 
  to 
  live 
  only 
  in 
  these 
  iutermediate 
  

   patches, 
  and 
  never 
  in 
  the 
  zostera 
  beds. 
  It 
  has 
  never 
  yet 
  been 
  

   obtained 
  from 
  any 
  other 
  locality 
  in 
  the 
  Plymouth 
  district. 
  

  

  I 
  propose 
  for 
  the 
  species 
  of 
  Pcecilochastus 
  found 
  at 
  

   Plymouth 
  and 
  described 
  in 
  this 
  paper, 
  the 
  name 
  

   P8ecilocha3tu8 
  serpens, 
  the 
  specific 
  name 
  being 
  selected 
  

   to 
  indicate 
  the 
  rapid, 
  wriggling 
  movement 
  both 
  of 
  the 
  larva 
  

   and 
  of 
  the 
  adult 
  worm 
  when 
  swimming. 
  

  

  