﻿234 
  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  adhere 
  laterally 
  to 
  the 
  sides 
  of 
  the 
  shell, 
  whilst 
  anteriorly 
  they 
  are 
  

   connected 
  with 
  the 
  anterior 
  adductor 
  muscle. 
  Proximally 
  their 
  fibres 
  

   pass 
  over 
  those 
  of 
  the 
  retractor 
  pedis 
  anterior 
  muscles, 
  and 
  terminate 
  

   in 
  the 
  pedal 
  integument. 
  

  

  The 
  retractor 
  pedis 
  posterior 
  muscle 
  (Fig. 
  2, 
  P.R.P.) 
  is 
  also 
  thick 
  

   and 
  short, 
  with 
  its 
  two 
  short 
  bifurcations 
  lying 
  on 
  the 
  antero-dorsal 
  

   surface 
  of 
  the 
  posterior 
  adductor 
  muscle, 
  and 
  its 
  distal 
  ends 
  attached 
  

   to 
  the 
  shell, 
  in 
  close 
  proximity 
  to 
  the 
  adductor 
  muscle. 
  The 
  fibres 
  of 
  

   its 
  proximal 
  part 
  are 
  traceable 
  running 
  in 
  a 
  longitudinal 
  direction 
  

   just 
  inside 
  the 
  pedal 
  integument. 
  

  

  The 
  elevator 
  pedis 
  muscles 
  are 
  situated 
  anteriorly 
  to 
  the 
  centre 
  of 
  

   the 
  dorsal 
  edge 
  of 
  the 
  foot, 
  and 
  their 
  muscle-fibres 
  are 
  likewise 
  soon 
  

   buried 
  in 
  the 
  pedal 
  integument. 
  

  

  Aliine7itary 
  Cmial. 
  — 
  The 
  mouth 
  (Figs. 
  3 
  and 
  4, 
  A, 
  A.) 
  is 
  situated 
  

   on 
  the 
  ventral 
  surface 
  close 
  to 
  the 
  anterior 
  adductor 
  muscle, 
  and 
  is 
  

   bordered 
  by 
  the 
  lips 
  which 
  are 
  continued 
  laterally 
  as 
  the 
  labial 
  palps 
  

   (Figs. 
  3 
  and 
  4, 
  A.L. 
  and 
  P.L.). 
  The 
  oesophagus 
  (Figs. 
  3 
  and 
  4, 
  Oe.) 
  

   is 
  long 
  and 
  dilated 
  from 
  the 
  centre 
  to 
  near 
  the 
  stomach. 
  Its 
  length 
  

   and 
  direction 
  (the 
  latter 
  being 
  more 
  or 
  less 
  dorso-posteriorly) 
  depend 
  

   upon 
  the 
  expansion 
  or 
  contraction 
  of 
  the 
  foot. 
  The 
  stomach 
  (Figs. 
  2, 
  

   3, 
  and 
  4, 
  St.) 
  is 
  an 
  irregularly 
  shaped 
  and 
  several-lobed 
  sac 
  occupying 
  

   the 
  dorsal 
  part 
  of 
  the 
  visceral 
  mass, 
  and 
  surrounded 
  by 
  the 
  digestive 
  

   gland 
  or 
  liver 
  (Fig. 
  2, 
  D.O.). 
  It 
  may 
  be 
  conveniently 
  separated 
  into 
  

   the 
  following 
  divisions, 
  oesophageal, 
  cardiac, 
  central, 
  and 
  pyloric, 
  each 
  

   being 
  distinguished 
  from 
  the 
  others 
  by 
  an 
  internal 
  raising 
  or 
  folding 
  of 
  

   the 
  gastric 
  wall, 
  or 
  the 
  varying 
  length 
  of 
  the 
  cells 
  of 
  the 
  epithelial 
  lining. 
  

   The 
  oesophageal 
  division 
  (Figs. 
  3 
  and 
  4, 
  Oe.St.) 
  is 
  small; 
  it 
  opens 
  into 
  

   the 
  oesophagus 
  at 
  the 
  fore-end, 
  and 
  posteriorly 
  is 
  bordered 
  by 
  the 
  folded 
  

   gastric 
  wall, 
  which 
  here 
  culminates 
  in 
  a 
  very 
  prominent 
  process, 
  

   separating 
  it 
  from 
  the 
  cardiac 
  division. 
  The 
  cardiac 
  division 
  (Figs. 
  3 
  

   and 
  4, 
  C.St.) 
  is 
  small, 
  and 
  continues 
  on 
  the 
  left 
  side 
  as 
  a 
  deep 
  pocket- 
  

   shaped 
  cavity. 
  On 
  the 
  right 
  side 
  its 
  separation 
  from 
  the 
  pyloric 
  

   division 
  is 
  indistinct. 
  The 
  above-mentioned 
  process 
  is 
  a 
  large 
  and 
  

   wide 
  projection 
  from 
  the 
  left 
  side 
  of 
  the 
  stomach 
  between 
  the 
  various 
  

   divisions, 
  and 
  is 
  supported 
  by 
  a 
  dense 
  mass 
  of 
  fibrous 
  connective 
  

   tissue. 
  The 
  cells 
  of 
  the 
  epithelium 
  lining 
  this 
  and 
  the 
  adjacent 
  parts 
  

   of 
  the 
  stomach 
  are 
  extremely 
  long 
  and 
  narrow. 
  Under 
  this 
  process 
  

   is 
  the 
  central 
  division 
  (Fig. 
  3, 
  CD.), 
  a 
  small 
  round 
  cavity 
  receiving 
  

   the 
  large 
  duct 
  from 
  the 
  digestive 
  gland. 
  The 
  pyloric 
  division 
  (Figs. 
  3 
  

   and 
  4, 
  P.St.) 
  is 
  large, 
  and 
  embraces 
  the 
  greater 
  portion 
  of 
  the 
  stomach. 
  

   On 
  its 
  ventral 
  surface, 
  towards 
  the 
  rear 
  end, 
  it 
  is 
  continued 
  as 
  a 
  very 
  

   long, 
  slightly 
  posteriorly, 
  curved 
  sac, 
  the 
  caecum 
  of 
  the 
  ciystalline 
  style 
  

   (Fig. 
  3, 
  C.C.). 
  The 
  crystalline 
  style 
  extends 
  all 
  along 
  the 
  caecum, 
  

   bends 
  anteriorly 
  on 
  entering 
  the 
  stomach, 
  and 
  stretches 
  along 
  it 
  to 
  

   the 
  anterior 
  wall, 
  frequently 
  at 
  this 
  point 
  it 
  curves, 
  and 
  nearly 
  fills 
  

   the 
  cardiac 
  division 
  as 
  well. 
  

  

  Covering 
  the 
  floor 
  of 
  the 
  stomach 
  and 
  entering 
  the 
  different 
  cavities 
  

   is 
  a 
  gelatinous 
  mass, 
  the 
  fleche 
  tricuspide, 
  which, 
  when 
  stained 
  with 
  

   Ehrlich's 
  haematoxylin, 
  appears 
  to 
  be 
  quite 
  structureless, 
  whilst 
  the 
  

   neighbouring 
  crystalline 
  style 
  exhibits 
  certain 
  concentric 
  markings, 
  

  

  