﻿278 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  9« 
  

  

  or 
  when 
  the 
  entrance 
  is 
  left 
  exposed 
  by 
  low 
  tide. 
  On 
  such 
  occasions 
  

   one 
  to 
  five 
  gobies 
  may 
  be 
  taken 
  from 
  the 
  upper 
  part 
  of 
  the 
  tunnel. 
  

   A 
  goby 
  left 
  at 
  the 
  laboratory 
  for 
  several 
  weeks 
  in 
  a 
  glass 
  burrow 
  ap- 
  

   peared 
  contented. 
  It 
  would 
  pass 
  from 
  one 
  end 
  to 
  the 
  other, 
  wriggling 
  

   past 
  the 
  Lrechis 
  as 
  if 
  accustomed 
  to 
  doing 
  so. 
  At 
  Newport 
  Bay 
  a 
  

   pair 
  of 
  either 
  Betaeus 
  longidactylus 
  Lockmgton 
  or 
  Crangon 
  [Alphaeus] 
  

   californiensis 
  (Holmes) 
  have 
  been 
  found 
  permanently 
  established 
  in 
  

   the 
  burrows 
  of 
  U?^echis. 
  The 
  former 
  is 
  also 
  recorded 
  from 
  Elkhorn 
  

   Slough 
  from 
  Urechis 
  burrows 
  (MacGinitie, 
  1935b, 
  p. 
  706). 
  

  

  Hesperonoe 
  adventor, 
  which 
  ranges 
  in 
  length 
  when 
  alive 
  from 
  15 
  to 
  

   50 
  mm,, 
  is 
  commensal 
  with 
  Lrechis 
  throughout 
  its 
  range 
  from 
  Hum- 
  

   boldt 
  Bay 
  to 
  Newport 
  Bay 
  and 
  normally 
  is 
  not 
  found 
  outside 
  the 
  

   burrows. 
  The 
  food 
  of 
  Hesperonoe 
  consists 
  of 
  particles 
  rejected 
  by 
  

   Lrechis 
  when 
  swallowing 
  its 
  slime 
  tube. 
  These 
  particles 
  consist 
  of 
  

   either 
  living 
  or 
  dead 
  animals 
  which 
  wash 
  down 
  the 
  burrow 
  with 
  the 
  

   current 
  and 
  become 
  entrapped 
  in 
  the 
  slime-net. 
  Sometmies 
  when 
  

   Lrechis 
  is 
  swallowing 
  its 
  slime 
  tube 
  the 
  polynoid 
  will 
  crawl 
  forward 
  and 
  

   eat 
  part 
  of 
  the 
  tube 
  and 
  contents. 
  It 
  is 
  very 
  aggressive 
  toward 
  in- 
  

   truders 
  within 
  the 
  burrow 
  other 
  than 
  the 
  commensal 
  crabs. 
  Only 
  one 
  

   Hesperonoe 
  occurs 
  within 
  each 
  burrow, 
  and 
  if 
  another 
  enters 
  the 
  two 
  

   will 
  fight 
  until 
  one 
  is 
  killed 
  or 
  driven 
  from 
  the 
  burrow. 
  Other 
  annelid 
  

   worms 
  wliich 
  may 
  find 
  their 
  way 
  into 
  the 
  burrow 
  are 
  speedily 
  dis- 
  

   patched 
  (by 
  means 
  of 
  the 
  short 
  eversible 
  toothed 
  proboscis) 
  and 
  

   devoured. 
  

  

  Hesperonoe 
  rests 
  with 
  its 
  dorsal 
  surface 
  in 
  contact 
  with 
  the 
  body 
  of 
  

   Lrechis, 
  moving 
  along 
  the 
  bm-row 
  with 
  the 
  latter 
  by 
  making 
  little 
  

   short 
  runs 
  as 
  the 
  peristaltic 
  movement 
  of 
  the 
  body 
  of 
  Lrechis 
  passes 
  

   by. 
  It 
  always 
  faces 
  in 
  the 
  same 
  du-ection 
  as 
  Lrechis, 
  and 
  when 
  the 
  

   latter 
  turns 
  in 
  its 
  burrow 
  the 
  annelid 
  quickly 
  does 
  likewise. 
  Hespero- 
  

   noe 
  is 
  also 
  commensal 
  in 
  Echiurus 
  tunnels. 
  

  

  Scleroplax 
  ranges 
  from 
  3 
  to 
  13 
  mm. 
  across 
  the 
  carapace 
  and 
  is 
  com- 
  

   mensal 
  also 
  in 
  the 
  tubes 
  of 
  Callianassa 
  calijorniensis 
  and 
  Upogebia 
  

   pugettensis. 
  It 
  rests 
  facing 
  the 
  side 
  of 
  the 
  burrow, 
  the 
  chelipeds 
  

   turned 
  up 
  in 
  front 
  and 
  the 
  last 
  pair 
  of 
  legs 
  raised 
  behind. 
  In 
  this 
  

   posture 
  it 
  can 
  travel 
  sidewise 
  along 
  the 
  tube 
  much 
  faster 
  than 
  its 
  host. 
  

   Its 
  food 
  consists 
  of 
  particles 
  which 
  wash 
  into 
  the 
  burrows 
  or 
  are 
  un- 
  

   covered 
  by 
  the 
  hosts. 
  Pinnixa 
  franciscana 
  screens 
  detritus 
  by 
  

   means 
  of 
  its 
  second 
  maxillipeds, 
  and 
  it 
  will 
  also 
  feed 
  on 
  particles 
  of 
  

   worms, 
  clams, 
  etc. 
  Scleroplax 
  has 
  never 
  been 
  observed 
  screening 
  

   plankton. 
  As 
  many 
  as 
  six 
  Scleroplax 
  have 
  been 
  taken 
  from 
  one 
  

   Lrechis 
  burrow. 
  A 
  male 
  and 
  a 
  female 
  are 
  often 
  found 
  together 
  or 
  two 
  

   females. 
  In 
  one 
  instance 
  an 
  ovigerous 
  female 
  was 
  found 
  with 
  an 
  

   ovigerous 
  Pinnixa, 
  and 
  in 
  another 
  burrow 
  a 
  male 
  Scleroplax 
  and 
  a 
  

   male 
  Pinnixa. 
  

  

  