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  PROCEEDINGS 
  OF 
  THK 
  MALACOLOGICAL 
  SOCIKTT. 
  

  

  under 
  the 
  sliade 
  of 
  the 
  Avicennia 
  mangrove. 
  At 
  low 
  tide 
  the 
  Phi/fia 
  

   crawls 
  over 
  the 
  mud 
  at 
  a 
  fair 
  pace, 
  and 
  if 
  placed 
  in 
  a 
  vessel 
  of 
  

   sea-water 
  it 
  soon 
  creeps 
  out 
  and 
  always 
  moves 
  steadily 
  away 
  from 
  

   the 
  light. 
  

  

  The 
  foot 
  is 
  small 
  and 
  narrow 
  for 
  the 
  size 
  of 
  the 
  shell. 
  There 
  is 
  

   no 
  operculum. 
  The 
  facial 
  area 
  is 
  darker 
  in 
  colour 
  and 
  covered 
  with 
  

   finer 
  tubercles 
  than 
  the 
  rest 
  of 
  the 
  animal; 
  it 
  is 
  marked 
  off 
  from 
  the 
  

   foot 
  by 
  a 
  groove 
  on 
  each 
  side. 
  When 
  the 
  animal 
  is 
  extended 
  

   the 
  tentacles 
  are 
  planted 
  well 
  apart, 
  hut 
  seem 
  to 
  spring 
  from 
  

   contiguous 
  bases 
  when 
  it 
  is 
  contracted. 
  They 
  are 
  subcylindrical, 
  

   slightly 
  tapering, 
  blunt 
  at 
  tlie 
  tips, 
  contractile 
  not 
  evagiiuite. 
  The 
  

   eyes 
  are 
  sunk 
  witliin 
  the 
  substance 
  of 
  the 
  tentacle 
  at 
  the 
  inner 
  base. 
  

   Near 
  the 
  tip 
  of 
  the 
  muzzle 
  are 
  two 
  wliite 
  oblong 
  marks 
  that 
  may 
  

   represent 
  the 
  smaller 
  tentacles 
  of 
  the 
  Helicidae. 
  

  

  The 
  muzzle 
  is 
  unusually 
  broad, 
  being 
  as 
  wide 
  as 
  the 
  foot. 
  

   Sometimes 
  it 
  is 
  emarginate 
  in 
  front 
  and 
  usually 
  recurved 
  at 
  the 
  

   margins. 
  The 
  mouth 
  is 
  in 
  the 
  centre 
  of 
  a 
  large 
  labial 
  disc. 
  Between 
  

   this 
  disc 
  and 
  tlie 
  fore-part 
  of 
  the 
  foot 
  is 
  a 
  shallow 
  pouch. 
  

  

  Here 
  there 
  seems 
  to 
  be 
  a 
  general 
  correspondence 
  to 
  the 
  pattern 
  of 
  

   Li/mtKsa, 
  the 
  chief 
  distinction 
  being 
  the 
  longer 
  and 
  narrower 
  tentacles 
  

   ■of 
  Fhytia. 
  

  

  Acclimatization 
  from 
  salt 
  water 
  to 
  fresh 
  is 
  easy 
  in 
  warm 
  

   temperatures, 
  but 
  difficult 
  in 
  cold. 
  So 
  it 
  was 
  perhaps 
  during 
  the 
  

   •warmer 
  periods 
  of 
  the 
  Eocene 
  or 
  Cretaceous 
  that 
  the 
  rich 
  Lymnseid 
  

   fauna 
  of 
  the 
  Northern 
  Hemisphere 
  arose 
  from 
  auriculoid 
  sources. 
  

  

  