﻿IKED 
  ALE 
  : 
  NOTES 
  ON 
  POLYPLACOPHORA. 
  97 
  

  

  examining 
  the 
  shells 
  in 
  the 
  British 
  Museum 
  from 
  various 
  Australian 
  

   localities 
  I 
  obtained 
  nothing 
  but 
  contradictions. 
  Awaiting 
  news 
  of 
  

   the 
  type 
  of 
  glauca, 
  Quoy 
  & 
  Gaimard, 
  I 
  dissected 
  a 
  typical 
  smooth 
  

   shell 
  from 
  South 
  Australia, 
  determined 
  as 
  glauca, 
  Q. 
  & 
  G., 
  by 
  

   Mr. 
  W. 
  T. 
  Bednall. 
  The 
  tail-valve 
  separated 
  it 
  at 
  once 
  from 
  the 
  

   Port 
  Jackson 
  corrugated 
  petholata, 
  Sow. 
  However, 
  Tasmanian 
  shells 
  

   from 
  the 
  Cuming 
  Collection, 
  labelled 
  petholata, 
  Sow., 
  and 
  recorded 
  

   in 
  the 
  Man. 
  Conch, 
  under 
  that 
  name, 
  were 
  identical 
  with 
  the 
  South 
  

   Australian 
  glauca. 
  

  

  Adams 
  & 
  Angas's 
  type 
  of 
  conspersa 
  was 
  next 
  dissected, 
  and 
  differed 
  

   only 
  slightly 
  fi'om 
  the 
  Port 
  Jackson 
  petliolata 
  in 
  internal 
  characters, 
  

   though 
  widely 
  so 
  in 
  colour. 
  Shells 
  sent 
  from 
  Port 
  Jackson 
  as 
  conspersa 
  

   Ad. 
  & 
  Aug., 
  were 
  simply 
  petliolata 
  of 
  brighter 
  coloration. 
  The 
  shells 
  

   sent 
  from 
  South 
  Australia 
  by 
  Bednall 
  were, 
  however, 
  quite 
  different 
  

   from 
  Adams 
  & 
  Angas's 
  type, 
  approaching 
  egregia, 
  H. 
  Ad., 
  more 
  than 
  

   any 
  other 
  Australian 
  Plaxiphora. 
  

  

  Shells 
  from 
  Queensland 
  turned 
  out 
  to 
  be 
  internally 
  identical 
  with 
  

   the 
  South 
  Australian 
  glauca, 
  though, 
  externally 
  faintly 
  corrugated. 
  

  

  Victorian 
  specimens, 
  though 
  of 
  dark 
  coloration, 
  agreed 
  better 
  with 
  

   conspersa, 
  Ad. 
  & 
  Aug., 
  than 
  vniih 
  p)etholata, 
  Sow., 
  from 
  Port 
  Jackson. 
  

  

  The 
  two 
  species 
  indicated 
  by 
  Mr. 
  Basset 
  Hull 
  appeared 
  to 
  be 
  easily 
  

   separable 
  by 
  means 
  of 
  the 
  sculpture, 
  and 
  the 
  second 
  species 
  I 
  have 
  not 
  

   yet 
  seen 
  from 
  any 
  other 
  locality 
  than 
  Port 
  Jackson. 
  

  

  I 
  had 
  thus 
  arrived 
  at 
  four 
  Australian 
  species 
  when 
  I 
  received 
  

   Dr. 
  Thiele's 
  "Revision 
  des 
  Systems 
  der 
  Chitonen 
  ", 
  which 
  caused 
  me 
  

   to 
  review 
  my 
  specimens 
  and 
  results. 
  Working 
  upon 
  the 
  characters 
  

   of 
  the 
  tail-valves 
  similarly 
  to 
  myself, 
  he 
  has 
  separated 
  five 
  species 
  

   without 
  considering 
  either 
  Adams 
  & 
  Angas's 
  conspersa 
  or 
  Bednall's 
  

   determination 
  of 
  that 
  species. 
  The 
  work 
  is 
  most 
  beautifully 
  illustrated 
  

   with 
  splendidly 
  drawn 
  figures 
  of 
  the 
  fifth 
  and 
  eighth 
  valves 
  of 
  his 
  

   species, 
  which 
  make 
  their 
  identification 
  simple. 
  However, 
  through 
  

   lack 
  of 
  specimens, 
  he 
  has 
  laid 
  too 
  much 
  stress 
  upon 
  the 
  value 
  of 
  the 
  

   shape 
  of 
  the 
  valves. 
  The 
  shape 
  varies 
  quite 
  considerably 
  with 
  age 
  

   and 
  environment, 
  specimens 
  living 
  exposed 
  to 
  heavy 
  breakers 
  having 
  

   much 
  longer 
  insertion 
  plates, 
  and 
  being 
  less 
  elevated 
  than 
  those 
  living 
  

   a 
  more 
  secluded 
  life. 
  Young 
  shells 
  are 
  also 
  more 
  strongly 
  sculptured 
  

   than 
  older 
  ones, 
  and 
  the 
  shape 
  of 
  their 
  valves 
  shows 
  differently. 
  The 
  

   big 
  smooth 
  petholata, 
  commonly 
  called 
  glauca, 
  Q. 
  & 
  G., 
  has 
  the 
  young 
  

   well 
  sculptured. 
  

  

  Having 
  examined 
  the 
  types 
  of 
  costatus, 
  Blain., 
  and 
  alhidus, 
  Blain., 
  these 
  

   names 
  are 
  fixed 
  by 
  Thiele 
  as 
  applicable 
  to 
  the 
  two 
  common 
  Australian 
  

   Plaxiphora. 
  He 
  va.dk.es, 
  petholata, 
  Sow., 
  synonymous 
  with 
  the 
  former, 
  

   but 
  the 
  latter 
  seems 
  nearest 
  to 
  the 
  commonly 
  accepted 
  petliolata. 
  Sow. 
  

   The 
  rejection 
  of 
  this 
  well-known 
  name, 
  though 
  repugnant, 
  appears 
  

   unavoidable, 
  especially 
  as 
  the 
  type 
  is 
  non-existent, 
  and 
  its 
  features 
  are 
  

   obscure. 
  Blainville's 
  costatus 
  is 
  easily 
  recognizable 
  as 
  the 
  species 
  

   I 
  have 
  above 
  noted 
  as 
  glauca, 
  Q. 
  & 
  G. 
  The 
  tail-valve 
  seems 
  distinctive. 
  

   Blainville's 
  alhidus 
  covers 
  the 
  majority 
  of 
  the 
  shells 
  commonly 
  known 
  

   in 
  Australia 
  2,% 
  petholata, 
  Sow., 
  and 
  is 
  the 
  shell 
  Adams 
  & 
  Angas 
  called 
  

   conspersa. 
  

  

  