﻿11 
  

  

  The. 
  transversely 
  elongated 
  mouth 
  M. 
  of 
  the 
  oyster 
  lies 
  

   between 
  the 
  upper 
  bends 
  of 
  the 
  palps, 
  it 
  is 
  followed 
  by 
  

   a 
  very 
  short 
  gullet 
  or 
  oesophagus 
  oe, 
  which 
  opens 
  into 
  

   tne 
  stomach 
  St, 
  the 
  walls 
  of 
  which 
  are 
  very 
  much 
  folded 
  

   and 
  wrinkled, 
  the 
  folds 
  often 
  dip 
  into 
  the 
  substance 
  of 
  

   the 
  massive 
  brownish 
  green 
  liver 
  L. 
  and 
  give 
  entrance 
  to 
  

   the 
  numerous 
  and 
  spacious 
  bile 
  ducts 
  of 
  the 
  latter. 
  At 
  

   the 
  hinder 
  end 
  of 
  the 
  stomach 
  one 
  of 
  the 
  deep 
  folds 
  ap- 
  

   pears 
  to 
  be 
  continued 
  backwards 
  in 
  the 
  form 
  of 
  a 
  blind, 
  

   cylindrical 
  pouch 
  to 
  or 
  beyond 
  and 
  between 
  the 
  o})enings 
  

   of 
  the 
  oviducts 
  of 
  either 
  side 
  ; 
  this 
  pouch 
  contains 
  a 
  

   transparent, 
  but 
  at 
  the 
  same 
  time 
  opalescent 
  rod, 
  the 
  

   so-called 
  crystalline 
  style 
  (' 
  .sf, 
  the 
  function 
  of 
  which 
  is 
  

   not 
  known. 
  The 
  intestine 
  as 
  it 
  lirst 
  leaves 
  the 
  stomach 
  

   proper 
  is 
  somewhat 
  wider 
  than 
  at 
  other 
  points, 
  but 
  I 
  do 
  

   not 
  know 
  why 
  Prof. 
  H. 
  J. 
  Clark 
  considered 
  this 
  por- 
  

   tion, 
  as 
  far 
  back 
  as 
  the 
  first 
  bend, 
  part 
  of 
  the 
  stomach. 
  

   It 
  seems 
  to 
  me 
  that 
  the 
  irregular 
  digestive 
  cavity 
  enclosed 
  

   in 
  the 
  liver-mass 
  should 
  be 
  regarded 
  as 
  the 
  stomach, 
  

   because 
  the 
  first 
  portion 
  of 
  the 
  intestine 
  already 
  contains 
  

   the 
  commencement 
  of 
  a 
  peculiar 
  pair 
  of 
  folds 
  running 
  

   lengthwise, 
  which 
  will 
  be 
  spoken 
  of 
  later. 
  Returning 
  to 
  

   the 
  course 
  of 
  the 
  intestine 
  Int, 
  after 
  passing 
  backwards 
  

   beneath 
  the 
  adductor 
  muscle, 
  into 
  the 
  mesosomal 
  or 
  

   middle 
  part 
  of 
  the 
  body, 
  wlien 
  it 
  suddenly 
  bends 
  and 
  is 
  

   prolonged 
  toward 
  the 
  head, 
  passing 
  a 
  little 
  to 
  the 
  right 
  

   of 
  the 
  stomach 
  and 
  along 
  the 
  back 
  of 
  the 
  animal, 
  when 
  

   it 
  again 
  suddenly 
  turns 
  to 
  the 
  left 
  and 
  crossing 
  the 
  gullet 
  

   oe, 
  descends 
  in 
  a 
  gentle 
  curve 
  along 
  the 
  left, 
  lower 
  side 
  

   of 
  the 
  body, 
  passing 
  obliquely 
  upwards 
  over 
  the 
  pericar- 
  

   dial 
  space 
  Per, 
  which 
  contains 
  the 
  heart, 
  to 
  end 
  in 
  the 
  

   anal 
  opening 
  at 
  V. 
  A 
  peculiar 
  double 
  fold, 
  /. 
  fids, 
  

   which 
  projects 
  into 
  the 
  intestinal 
  cavity, 
  extends 
  from 
  

   the 
  pyloric 
  end 
  of 
  the 
  intestine 
  to 
  the 
  vent 
  ; 
  its 
  function 
  

   is 
  probably 
  to 
  aflford 
  a 
  greater 
  amount 
  of 
  surface 
  for 
  the 
  

   absorption 
  of 
  nutriment, 
  or 
  it 
  maybe 
  valvular 
  in 
  charac- 
  

   ter. 
  The 
  greater 
  portion 
  of 
  the 
  inner 
  intestinal 
  surfaces 
  

  

  