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  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  wide 
  range 
  of 
  the 
  Tectibranchs 
  suggested 
  inquiry, 
  and 
  almost 
  the 
  

   first 
  one 
  I 
  examined 
  revealed 
  the 
  adult 
  of 
  my 
  imperforate 
  ^ 
  Agadina 
  ', 
  

   namely 
  Bullina 
  scalra, 
  Gmelin. 
  I 
  then 
  carefully 
  examined 
  the 
  whole 
  

   of 
  my 
  Kermadee 
  Tectibranchs, 
  with 
  the 
  results 
  that 
  I 
  believe 
  the 
  

   majority 
  owed 
  their 
  distribution 
  to 
  ' 
  Agadina^ 
  larva. 
  In 
  some 
  cases 
  

   it 
  was 
  apparent, 
  in 
  others 
  only 
  suggested. 
  Thus 
  BuUaria 
  gave 
  it, 
  

   Pleurohranchus 
  showed 
  it, 
  Dolahrifer 
  and 
  Umhraculum 
  apparently 
  

   possess 
  it, 
  whilst 
  I 
  could 
  not 
  get 
  juveniles 
  of 
  others 
  of 
  which 
  the 
  

   adults 
  gave 
  indeterminate 
  results. 
  I 
  have 
  said 
  we 
  do 
  not 
  yet 
  know 
  

   the 
  absolute 
  character 
  of 
  the 
  juveniles 
  of 
  Stromhus, 
  but 
  the 
  apices 
  of 
  

   some 
  species 
  are 
  clearly 
  swimmers, 
  though 
  of 
  quite 
  a 
  peculiar 
  nature. 
  

   CyprcBa, 
  I 
  believe, 
  has 
  a 
  Simmgera 
  juvenile 
  : 
  T 
  have 
  examined 
  

   young 
  specimens 
  showing 
  apices 
  clearly 
  comparable 
  with 
  a 
  Thaitid 
  

   apex, 
  but 
  the 
  post-embryonic 
  whorls 
  clasp 
  the 
  embryo 
  so 
  high 
  up 
  

   that 
  tlie 
  absence 
  or 
  presence 
  of 
  a 
  claw 
  cannot 
  be 
  even 
  guessed 
  at. 
  

   A 
  similar 
  apex 
  and 
  similar 
  remarks 
  apply 
  to 
  Harpa, 
  whilst 
  I 
  have 
  

   been 
  unable 
  to 
  get 
  any 
  clue 
  whatever 
  as 
  to 
  the 
  nature 
  of 
  the 
  apex 
  of 
  

   Conus. 
  The 
  apex 
  of 
  lanthina 
  has 
  been 
  often 
  described, 
  but 
  here 
  again 
  

   I 
  cannot 
  decide 
  whether 
  it 
  is 
  a 
  Simmgera 
  or 
  not, 
  though 
  my 
  best 
  

   specimens 
  certainly 
  point 
  to 
  the 
  affirmative. 
  

  

  Now 
  the 
  mass 
  of 
  work 
  to 
  be 
  done 
  on 
  the 
  apices 
  of 
  described 
  shells 
  

   is 
  surely 
  apparent, 
  and 
  I 
  believe 
  our 
  present 
  classifications 
  will 
  be 
  

   considerably 
  improved 
  when 
  we 
  know 
  the 
  nature 
  of 
  the 
  juveniles 
  

   of 
  our 
  molluscs. 
  I 
  consider 
  that 
  basing 
  our 
  systems 
  even 
  upon 
  the 
  

   nature 
  of 
  the 
  animals, 
  without 
  taking 
  into 
  consideration 
  the 
  character 
  

   of 
  the 
  juveniles, 
  is 
  a 
  mistake. 
  In 
  every 
  other 
  branch 
  of 
  science 
  the 
  

   study 
  of 
  juvenile 
  forms 
  has 
  led 
  to 
  results 
  of 
  the 
  greatest 
  importance, 
  

   and 
  I 
  think 
  that 
  will 
  be 
  found 
  to 
  apply 
  to 
  the 
  Marine 
  MoUusca. 
  At 
  

   present 
  the 
  majority 
  of 
  the 
  genera 
  commonly 
  in 
  use 
  are 
  heterogeneous, 
  

   obviously 
  so, 
  yet 
  when 
  a 
  writer 
  splits 
  them 
  up 
  instead 
  of 
  an 
  attempt 
  

   being 
  made 
  to 
  confirm 
  or 
  reject 
  his 
  conclusions, 
  they 
  are 
  ignored. 
  

   I 
  liave 
  instanced 
  the 
  case 
  of 
  ' 
  Thais 
  ' 
  lapillus, 
  L., 
  and 
  succincta, 
  

   Lamarck: 
  it 
  might 
  be 
  thought 
  that 
  this 
  lumping 
  was 
  due 
  to 
  the 
  

   fact 
  that 
  no 
  one 
  had 
  pointed 
  out 
  the 
  error. 
  But 
  it 
  has 
  been 
  often 
  

   indicated, 
  and 
  Troschel, 
  working 
  upon 
  the 
  radular 
  characters, 
  split 
  up 
  

   the 
  genus 
  Thais 
  [Purpura 
  as 
  it 
  was 
  at 
  tliat 
  time 
  called) 
  into 
  several 
  

   genera. 
  Though 
  it 
  is 
  acknowledged 
  by 
  every 
  careful 
  worker 
  that 
  

   Thais 
  is 
  a 
  mixture 
  of 
  incongruous 
  elements, 
  no 
  one 
  has 
  definitely 
  

   criticized 
  Troschel's 
  action, 
  but 
  as 
  far 
  as 
  I 
  can 
  see 
  simply 
  overlooked 
  

   it 
  and 
  continued 
  the 
  perpetuation 
  of 
  obvious 
  errors. 
  I 
  believe 
  that 
  

   a 
  study 
  of 
  the 
  apices 
  of 
  this 
  group 
  would 
  lead 
  to 
  a 
  reorganization 
  of 
  

   our 
  ideas, 
  and 
  confirmation 
  or 
  rejection 
  of 
  the 
  divisions 
  proposed 
  by 
  

   Troschel. 
  My 
  own 
  incomplete 
  studies 
  suggest 
  that 
  Troschel's 
  genera 
  

   are, 
  to 
  a 
  great 
  extent, 
  natural. 
  

  

  Another 
  instance 
  is 
  the 
  genus 
  Triphora. 
  Here 
  again 
  the 
  work 
  of 
  

   subdivision 
  has 
  been 
  done 
  so 
  that 
  the 
  apical 
  features 
  can 
  be 
  used 
  for 
  

   confirmatory 
  purposes. 
  As 
  a 
  matter 
  of 
  fact, 
  every 
  one 
  who 
  has 
  

   handled 
  many 
  specimens 
  of 
  Triphora 
  knows 
  the 
  beautiful 
  and 
  diverse 
  

   styles 
  of 
  apex 
  that 
  occur 
  in 
  that 
  genus. 
  It 
  is 
  an 
  impossibility 
  for 
  one 
  

   individual 
  to 
  work 
  out 
  the 
  many 
  complex 
  problems 
  that 
  are 
  presented 
  

  

  