﻿lEEDALE 
  & 
  may: 
  MISNAMKD 
  TASMANIAN 
  CHITONS. 
  101 
  

  

  means 
  of 
  a 
  few 
  shells 
  only. 
  P. 
  mattJmvsi, 
  Iredale, 
  is 
  not 
  involved 
  in 
  

   the 
  above 
  medley, 
  and 
  we 
  think 
  one 
  of 
  the 
  other 
  species 
  would 
  quickly 
  

   be 
  eliminated 
  were 
  collections 
  available. 
  We 
  liave 
  taken 
  the 
  oppor- 
  

   tunity 
  of 
  figuring 
  P. 
  mattheiosi, 
  Iredale, 
  from 
  a 
  Tasmanian 
  specimen 
  

   so 
  determined 
  (PL 
  V, 
  Fig. 
  4). 
  When 
  it 
  was 
  described 
  the 
  peculiar 
  

   formation 
  of 
  the 
  tail-valve 
  which 
  suggested 
  Fremhleya 
  was 
  remarked 
  

   upon. 
  Receipt 
  of 
  well-preserved 
  specimens 
  from 
  Tasmania 
  show 
  

   that 
  the 
  species 
  has 
  no 
  close 
  relationship 
  with 
  Fremhleya, 
  the 
  animal 
  

   being 
  obviously 
  different. 
  This 
  is 
  now 
  being 
  investigated, 
  but 
  in 
  the 
  

   meanwhile 
  a 
  nearer 
  ally 
  from 
  a 
  superficial 
  examination 
  might 
  be 
  

   Loricella. 
  This 
  statement 
  should 
  prove 
  how 
  extremely 
  interestinf' 
  

   tins 
  species 
  is, 
  and 
  we 
  hope 
  that 
  its 
  exact 
  status 
  will 
  be 
  soon 
  fixed 
  

   The 
  valve 
  slitting 
  recalls 
  that 
  of 
  Callistochiton, 
  and 
  we 
  note 
  hereafter 
  

   thatThiele 
  associated 
  Lorica, 
  Loricella, 
  SquamopJiora, 
  and 
  Callistochiton 
  

   together. 
  We 
  discuss 
  the 
  association 
  later, 
  but 
  believe 
  most 
  of 
  the 
  

   resemblances 
  of 
  this 
  species 
  are 
  simply 
  due 
  to 
  convergence 
  in 
  develop- 
  

   ment, 
  and 
  are 
  not 
  of 
  phylogenetic 
  import. 
  

  

  4. 
  ACANTHOCHITONS. 
  

  

  Torr, 
  in 
  his 
  essay 
  on 
  South 
  Australian 
  Polvplacophora, 
  observed, 
  

   '' 
  A 
  splendid 
  opportunity 
  awaits 
  the 
  student 
  who 
  will 
  make 
  this 
  

   field^ 
  a 
  special 
  study," 
  and 
  recorded 
  sixteen 
  species. 
  We 
  confirm 
  

   lorr's 
  statement, 
  and 
  as 
  an 
  aid 
  give 
  the 
  following 
  notes. 
  First 
  it 
  is 
  

   now 
  necessary 
  for 
  the 
  student 
  to 
  collect 
  in 
  quantitv, 
  as 
  we 
  find 
  tlie 
  

   species 
  difficult 
  to 
  delimit 
  without 
  long 
  series. 
  It 
  will 
  be 
  necessary 
  

   to 
  continually 
  use 
  the 
  microscope, 
  and 
  very 
  many 
  specimens 
  must 
  be 
  

   dissected. 
  

  

  The 
  difficulty 
  of 
  distinguishing 
  these 
  Chitons 
  may 
  be 
  lessened 
  bv 
  

   the 
  usage 
  of 
  narrow 
  generic 
  groupings. 
  Thus 
  one 
  of 
  us 
  advocated 
  

   the 
  usage 
  of 
  six 
  generic 
  names, 
  viz. 
  : 
  Acanthochitona, 
  Cryptoconchus, 
  

   tryptoplax, 
  Notoplax, 
  Macandrellus, 
  and 
  Craspedochiton. 
  This 
  was 
  

   after 
  _ 
  consideration 
  of 
  Thiele's 
  classification, 
  which 
  was 
  based 
  on 
  

   ■examination 
  of 
  the 
  radula 
  as 
  well 
  as 
  microscopic 
  shell-characters, 
  and 
  

   winch 
  reads 
  : 
  — 
  

  

  " 
  Genus 
  Craspedochiton 
  and 
  subgenus 
  Thaumastochiton. 
  

  

  Genus 
  Aristochiton. 
  

  

  Genus 
  Cryptoconchus 
  with 
  subgenus 
  Spongiochiton 
  and 
  sections 
  

   Leptoplax 
  and 
  Notoplax. 
  

  

  Genus 
  Acanthochites?'' 
  

  

  If 
  this 
  be 
  accepted 
  the 
  following 
  alterations 
  are 
  necessary 
  on 
  

   nomenclatural 
  grounds 
  alone. 
  Firstly, 
  regarding 
  the 
  genus 
  Crypto- 
  

   conchus 
  with 
  subgenus 
  Notoplax 
  and 
  sections 
  Leptoplax 
  and 
  

   Macandrellus. 
  Notoplax 
  is 
  older 
  than 
  Macandrellus, 
  which 
  equals 
  

   tipongiochiton 
  and 
  Loboplax. 
  We, 
  however, 
  would 
  prefer 
  Iredale's 
  

   arrangement 
  with 
  the 
  amendment 
  that 
  Macandrelbis 
  may 
  fall 
  as 
  an 
  

   absolute 
  synonym 
  of 
  Notoplax. 
  We 
  have 
  Tasmanian 
  species 
  which 
  

   completely 
  combine 
  any 
  superficial 
  differences 
  apparent 
  in 
  the 
  types 
  

   ot 
  the 
  two 
  generic 
  groups. 
  We 
  would 
  note, 
  however, 
  that 
  Thiele 
  

   referred 
  the 
  Neozelanic 
  species 
  '' 
  rubiyinosus, 
  Hutton" 
  to 
  Loboplax 
  = 
  

  

  VOL. 
  XII.— 
  NOV. 
  1916. 
  Q 
  

  

  