﻿208 
  PEOCEKDINGS 
  OF 
  THE 
  MALACOI.OGICAL 
  SOCIETi'. 
  

  

  ON 
  THE 
  ANATOMY 
  OF 
  liHYSOTA 
  FOULLIOYI. 
  

   By 
  E,. 
  H. 
  BuRNE, 
  M.A. 
  

  

  Read 
  lOth 
  June, 
  1910. 
  

  

  PLATES 
  VII 
  AND 
  VIII. 
  

  

  The 
  specimen 
  described 
  below 
  came 
  from 
  Few 
  Guinea 
  and 
  was 
  

   kindly 
  given 
  to 
  me 
  for 
  dissection 
  by 
  the 
  Secretary 
  of 
  the 
  Society, 
  

   Mr. 
  G. 
  K. 
  Gude, 
  to 
  wbom 
  I 
  wish 
  to 
  tender 
  my 
  best 
  thanks 
  for 
  the 
  

   opportunity 
  of 
  examining 
  it. 
  It 
  was 
  in 
  excellent 
  condition. 
  

  

  External 
  Appearance. 
  

  

  The 
  snail 
  was 
  slightly 
  contracted, 
  the 
  tentacles 
  and 
  fore-part 
  of 
  the 
  

   foot 
  being 
  withdrawn. 
  

  

  The 
  general 
  ground 
  colour 
  of 
  the 
  body 
  and 
  foot 
  is 
  buff 
  yellow, 
  

   fairly 
  pure 
  upon 
  the 
  parts 
  of 
  the 
  foot 
  normally 
  protected 
  by 
  the 
  

   overhanging 
  shell, 
  but 
  upon 
  the 
  head 
  and 
  tail 
  dusky, 
  and 
  clouded 
  

   with 
  black, 
  as 
  if 
  the 
  snail 
  had 
  been 
  dipped 
  in 
  ink 
  and 
  the 
  supeifluous 
  

   ink 
  washed 
  off. 
  

  

  The 
  sole 
  of 
  the 
  foot 
  is 
  pure 
  buff 
  yellow, 
  and 
  is 
  not 
  divided 
  into 
  

   median 
  and 
  lateral 
  areas. 
  

  

  The 
  upper 
  surface 
  of 
  the 
  foot 
  behind 
  the 
  shell 
  is 
  bluntly 
  keeled. 
  

   The 
  posterior 
  end 
  is 
  truncated 
  and 
  deeply 
  cleft 
  by 
  a 
  cruciform, 
  or 
  

   probably 
  in 
  the 
  expanded 
  state 
  pear-shaped, 
  mucous 
  pore. 
  The 
  upper 
  

   lip 
  of 
  the 
  pore 
  is 
  slightly 
  prominent, 
  but 
  does 
  not 
  form 
  a 
  definite 
  

   ' 
  horn 
  ' 
  (fig. 
  1). 
  

  

  The 
  edge 
  of 
  the 
  foot 
  is 
  bordered 
  by 
  a 
  double 
  selvage 
  or 
  marginal 
  

   band 
  (fig. 
  1). 
  The 
  lower 
  band 
  is 
  twice 
  the 
  breadth 
  of 
  the 
  upper, 
  and 
  

   meets 
  its 
  fellow 
  posteriorly 
  above 
  the 
  mucous 
  pore. 
  It 
  is 
  banded 
  

   with 
  vertical 
  blaciv 
  stripes, 
  which 
  with 
  fair 
  regularity 
  are 
  alternately 
  

   broad 
  and 
  narrow. 
  The 
  upper 
  baud 
  originates 
  in 
  front, 
  below 
  the 
  

   posterior 
  extremity 
  of 
  the 
  lateral 
  lip, 
  and 
  is 
  at 
  first 
  a 
  definite 
  though 
  

   small 
  fold 
  overhanging 
  the 
  lower 
  band. 
  However, 
  throughout 
  

   practically 
  the 
  whole 
  length 
  of 
  the 
  foot, 
  the 
  two 
  bands 
  are 
  separated 
  

   only 
  by 
  a 
  narrow 
  groove. 
  In 
  a 
  similar 
  way 
  the 
  upper 
  band 
  is 
  bounded 
  

   above 
  by 
  a 
  narrow 
  groove, 
  and 
  is 
  I'urther 
  divided 
  by 
  vertical 
  grooves 
  

   into 
  a 
  series 
  of 
  quadrangular 
  areas, 
  whose 
  boundaries 
  in 
  the 
  main 
  

   correspond 
  with 
  the 
  broader 
  black 
  lines 
  of 
  the 
  lower 
  border. 
  Above, 
  

   a 
  series 
  of 
  grooves 
  pass 
  upwards 
  from 
  the 
  margin 
  of 
  the 
  upper 
  band, 
  

   and 
  are 
  lost 
  towards 
  the 
  mid-dorsal 
  line 
  of 
  the 
  foot. 
  

  

  The 
  mouth 
  (fig. 
  7) 
  is 
  encircled 
  by 
  a 
  beaded 
  lip. 
  Between 
  the 
  chin 
  

   and 
  the 
  foot 
  are 
  a 
  pair 
  of 
  thin 
  lateral 
  lips 
  (fig. 
  7, 
  L'-) 
  that 
  project 
  forward 
  

   in 
  the 
  horizontal 
  plane 
  and 
  extend 
  from 
  beneath 
  the 
  lesser 
  tentacle 
  

   to 
  the 
  anterior 
  mid-line. 
  

  

  The 
  mantle 
  border 
  (fig. 
  2) 
  is 
  provided 
  with 
  strongly 
  developed 
  

   cervical 
  lobes. 
  Shell 
  lobes 
  are 
  absent. 
  

  

  The 
  right 
  cervical 
  lobe 
  towards 
  the 
  left 
  forms 
  the 
  floor 
  of 
  the 
  

   respiratory 
  orifice 
  and 
  is 
  here 
  produced 
  as 
  a 
  free 
  process 
  for 
  some 
  

  

  