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  THE 
  OYSTEK 
  CHAB 
  AS 
  MESSMATE 
  AND 
  IM'HVEYOK. 
  

  

  It 
  is 
  many 
  years 
  since 
  Mr. 
  Say 
  named 
  tlie 
  little 
  oyster- 
  

   crab 
  of 
  oiii' 
  coasts 
  Pinaotlierei<! 
  ostreum, 
  and 
  its 
  habits 
  in 
  

   relation 
  to 
  the 
  oyster 
  seem 
  to 
  liave 
  excited 
  but 
  little 
  in- 
  

   terest. 
  esi)ecially 
  in 
  foreign 
  writers. 
  Prof. 
  \^errill, 
  in 
  

   his 
  report 
  to 
  the 
  U. 
  S. 
  Fish 
  Commission, 
  observes 
  that 
  it 
  

   is 
  the 
  female 
  which 
  lives 
  in 
  the 
  oyster, 
  and 
  that 
  the 
  male 
  

   which 
  is 
  smaller 
  and 
  quite 
  unlike 
  the 
  female, 
  is 
  rarely, 
  

   if 
  ever 
  seen 
  to 
  occur, 
  but 
  that 
  it 
  has 
  been 
  seen 
  by 
  him 
  

   swimming 
  at 
  the 
  surface 
  of 
  the 
  water 
  in 
  the 
  middle 
  of 
  

   Vineyard 
  Sound. 
  His 
  statement 
  that 
  it 
  occurs 
  whei'ever 
  

   oysters 
  occur, 
  I 
  cannot 
  agree 
  with, 
  since 
  out 
  of 
  many 
  

   hundreds 
  of 
  St. 
  Jerome's 
  oysters 
  which 
  I 
  saw 
  opened, 
  I 
  

   never 
  saw 
  a 
  si)ecimen 
  of 
  Pinnotheres 
  ; 
  they 
  may 
  occur, 
  

   but 
  rarely. 
  This 
  little 
  crab 
  has 
  quite 
  a 
  number 
  of 
  allies 
  

   w^hich 
  inhabit 
  various 
  living 
  mollusks, 
  holothurians, 
  etc., 
  

   of 
  which 
  admirable 
  accounts 
  are 
  given 
  by 
  Van 
  Beneden 
  

   in 
  his 
  work 
  on 
  Animal 
  Parasites 
  and 
  Messmates. 
  

  

  There 
  can 
  be 
  wo 
  doubt 
  that 
  the 
  oyster-crab 
  is 
  a 
  true 
  

   messmate, 
  and 
  it 
  is 
  highly 
  i)robable 
  that 
  the 
  presence 
  of 
  

   these 
  animals 
  in 
  the 
  oyster 
  is 
  rather 
  to 
  be 
  regarded 
  as 
  

   advantageous 
  than 
  otherwise. 
  The 
  animal 
  lives 
  in 
  the 
  

   gill 
  cavity 
  of 
  the 
  oyster, 
  and, 
  as 
  will 
  be 
  seen 
  from 
  the 
  

   following 
  observations, 
  may 
  be 
  the 
  means 
  of 
  indirectly 
  

   supplying 
  its 
  host 
  with 
  a 
  part 
  of 
  its 
  food. 
  During 
  a 
  

   reconnoitering 
  trip 
  down 
  the 
  Chesapeake 
  oh 
  the 
  yacht 
  

   "Lookout," 
  in 
  the 
  first 
  week 
  of 
  July 
  last, 
  in 
  dredging, 
  

   some 
  oysters 
  were 
  hauled 
  uv) 
  wliicli 
  contained 
  Pinnothe- 
  

   res. 
  In 
  the 
  case 
  which 
  I 
  am 
  about 
  to 
  describe, 
  the 
  inclu- 
  

   ded 
  crab 
  was 
  a 
  female 
  with 
  the 
  curiously 
  expanded 
  

   abdomen 
  folded 
  forwards 
  under 
  the 
  thoi-ax 
  and 
  pai-tially 
  

   covering 
  a 
  huge 
  mass 
  of 
  brownish 
  eggs. 
  Upon 
  examin- 
  

   ing 
  thesp 
  eggs 
  wliat 
  was 
  my 
  astonishment 
  to 
  find 
  that 
  

   they 
  afforded 
  attachment 
  to 
  a 
  great 
  number 
  of 
  compound 
  

   colonies 
  of 
  the 
  singular 
  bell 
  animalcule, 
  Zobthanmium 
  

   arbuscit.hnii. 
  I'pcm 
  further 
  examination 
  it 
  was 
  found 
  

   that 
  the 
  legs 
  and 
  back 
  of 
  the 
  animal 
  also 
  afforded 
  points 
  

  

  