﻿6 
  

  

  disturbed 
  upon 
  the 
  bottom, 
  or 
  wlien 
  its 
  muscle 
  is 
  cut, 
  or 
  when 
  

   the 
  animal 
  is 
  dying 
  or 
  dead, 
  the 
  edges 
  of 
  the 
  shell 
  are 
  sepa- 
  

   rated 
  a 
  little. 
  

  

  The 
  shell 
  is 
  lined 
  by 
  a 
  thin 
  membrane, 
  the 
  mantle, 
  which 
  

   folds 
  down 
  on 
  each 
  side, 
  and 
  may 
  be 
  compared 
  to 
  the 
  leaf 
  next 
  

   the 
  cover 
  on 
  each 
  side 
  of 
  the 
  book. 
  The 
  next 
  two 
  leaves 
  of 
  

   each 
  side 
  roughly 
  represent 
  the 
  four 
  gills, 
  the 
  so-called 
  " 
  beard 
  " 
  

   of 
  the 
  oyster, 
  which 
  hang 
  down 
  like 
  leaves 
  into 
  the 
  space 
  

   inside 
  the 
  two 
  lobes 
  of 
  the 
  mantle. 
  The 
  remaining 
  leaves, 
  

   may 
  be 
  compared 
  to 
  the 
  body 
  or 
  visceral 
  fnass 
  of 
  the 
  oyster.. 
  

  

  Although 
  the 
  oyster 
  lies 
  upon 
  the 
  bottom 
  with 
  one 
  shell 
  

   above 
  and 
  one 
  below, 
  the 
  shells 
  are 
  not 
  upon 
  the 
  top 
  and 
  bot- 
  

   tom 
  of 
  the 
  body, 
  but 
  upon 
  the 
  right 
  and 
  the 
  left 
  sides. 
  The 
  

   two 
  shells 
  are 
  synmietrical 
  in 
  the 
  young 
  oyster, 
  but 
  after 
  it 
  

   becomes 
  attached 
  the 
  lower 
  or 
  attached 
  side 
  grows 
  faster 
  than 
  

   the 
  other, 
  and 
  becomes 
  deep 
  and 
  spoon-shaped, 
  while 
  the 
  free 
  

   valve 
  remains 
  nearly 
  flat. 
  In 
  nearly 
  every 
  case, 
  the 
  lower 
  or 
  

   deep 
  valve 
  is 
  the 
  left. 
  As 
  the 
  hinge 
  marks 
  the 
  anterior 
  end 
  

   of 
  the 
  body, 
  an 
  oyster 
  which 
  is 
  held 
  on 
  edge 
  with 
  the 
  hinge 
  

   away 
  from 
  the 
  observer 
  and 
  the 
  flat 
  valve 
  on 
  the 
  right 
  side,, 
  

   will 
  be 
  placed 
  with 
  its 
  dorsal 
  surface 
  uppermost, 
  its 
  ventral 
  

   surface 
  below, 
  its 
  anterior 
  end 
  away 
  from 
  the 
  observer, 
  and 
  its 
  

   posterior 
  end 
  towards 
  him, 
  and 
  its 
  right 
  and 
  left 
  sides 
  on 
  Im 
  

   right 
  and 
  left 
  hands 
  respectively. 
  

  

  In 
  order 
  to 
  examine 
  the 
  soft 
  parts, 
  the 
  oyster 
  should 
  be 
  

   opened 
  by 
  gently 
  working 
  a 
  thin 
  flat 
  knife 
  blade 
  under 
  the 
  

   posterior 
  end 
  of 
  the 
  right 
  valve 
  of 
  the 
  shell, 
  and 
  pushing 
  the 
  

   blade 
  forwards 
  until 
  it 
  strikes 
  and 
  cuts 
  the 
  strong 
  adductor 
  

   muscle, 
  which 
  passes 
  from 
  one 
  shell 
  to 
  another 
  and 
  pulls 
  them 
  

   together. 
  As 
  soon 
  as 
  this 
  muscle 
  is 
  cut 
  the 
  valves 
  separate 
  a- 
  

   little, 
  and 
  the 
  right 
  valve 
  may 
  be 
  raised 
  up 
  and 
  broken 
  ofi" 
  from 
  

   the 
  left, 
  thus 
  exposing 
  the 
  right 
  side 
  of 
  the 
  body. 
  The 
  sur- 
  

   face 
  of 
  the 
  body 
  is 
  covered 
  by 
  the 
  mantle, 
  a 
  thin 
  membrane 
  

   which 
  is 
  attached 
  to 
  the 
  body 
  over 
  a 
  great 
  part 
  of 
  its 
  surface,, 
  

   but 
  hangs 
  free 
  like 
  a 
  curtain 
  around 
  nearly 
  the 
  whole 
  circum- 
  

   ference. 
  By 
  raising 
  its 
  edge, 
  or 
  gently 
  tearing 
  the 
  whole 
  

   right 
  half 
  away 
  from 
  the 
  body, 
  the 
  gills 
  will 
  be 
  exposed- 
  

  

  