﻿INTRODUCTION. 
  Panama 
  Shells. 
  249 
  

  

  Ocean, 
  New 
  Holland, 
  &c., 
  we 
  may 
  often 
  suspect 
  the 
  error 
  to 
  

   arise 
  more 
  or 
  less 
  from 
  erroneous 
  testimony. 
  But 
  when 
  one 
  

   species 
  is 
  referred 
  to 
  two 
  distinct 
  zoological 
  provinces, 
  which 
  

   are 
  known 
  to 
  contain 
  analogous 
  but 
  not 
  identical 
  species, 
  we 
  

   must 
  sometimes 
  suspect 
  the 
  author 
  of 
  confounding 
  such 
  species. 
  

   If 
  indeed 
  in 
  these 
  cases 
  the 
  difference 
  of 
  the 
  local 
  types 
  were 
  

   clearly 
  distinguished, 
  it 
  would 
  be 
  of 
  little 
  importance 
  whether 
  

   or 
  not 
  the 
  difference 
  were 
  considered 
  to 
  be 
  of 
  specific 
  value. 
  

   But 
  not 
  even 
  after 
  the 
  specimens 
  are 
  deposited 
  in 
  a 
  collection 
  

   has 
  all 
  danger 
  of 
  error 
  ceased. 
  A 
  misplacement 
  of 
  labels 
  or 
  

   of 
  shells, 
  which 
  are 
  not 
  properly 
  secured, 
  may 
  lead 
  to 
  

   erroneous 
  statements 
  of 
  habitat. 
  

  

  For 
  all 
  these 
  causes 
  of 
  error 
  there 
  is 
  but 
  one 
  remedy, 
  and 
  

   that 
  is 
  not 
  infallible. 
  Rejecting 
  the 
  testimony 
  of 
  careless 
  

   and 
  incompetent 
  observers, 
  and 
  all 
  hearsay 
  testimony, 
  we 
  

   must 
  rely 
  on 
  the 
  testimony 
  of 
  competent 
  observers. 
  We 
  may 
  

   hope 
  for 
  accuracy 
  when 
  they 
  shall 
  remember 
  that 
  a 
  very 
  few 
  

   errors 
  may 
  essentially 
  change 
  the 
  aspect 
  of 
  the 
  plan 
  of 
  dis- 
  

   tribution, 
  and 
  prevent 
  all 
  correct 
  generalizations. 
  

  

  A 
  great 
  amount 
  of 
  valuable 
  materials, 
  for 
  interesting 
  

   generalizations 
  on 
  the 
  number 
  and 
  distribution 
  of 
  the 
  species 
  

   of 
  marine 
  Mollusks, 
  has 
  been 
  collected 
  by 
  public 
  and 
  private 
  

   expeditions. 
  But 
  when 
  we 
  consider 
  the 
  immense 
  profusion 
  

   of 
  species 
  and 
  of 
  individuals 
  in 
  tropical 
  seas, 
  and 
  the 
  confu- 
  

   sion 
  of 
  the 
  habitats 
  of 
  many 
  as 
  exhibited 
  in 
  the 
  present 
  

   literature 
  of 
  conchology, 
  so 
  that 
  the 
  plan 
  of 
  distribution 
  is 
  

   misrepresented, 
  — 
  that 
  which 
  has 
  been 
  done 
  only 
  stimulates 
  

  

  may 
  happen 
  in 
  casual 
  collections. 
  By 
  a 
  singular 
  coincidence, 
  only 
  a 
  few 
  days 
  

   after 
  we 
  had 
  described 
  Helix 
  Redfieldiana 
  (wiiicli 
  proves 
  to 
  be 
  H. 
  Carmelita 
  Fer.) 
  

   that 
  inhabits 
  a 
  limited 
  district 
  in 
  Jamaica, 
  a 
  specmien 
  was 
  brought 
  to 
  New-York 
  

   by 
  a 
  collector, 
  who 
  affirmed 
  that 
  he 
  procured 
  it 
  in 
  California. 
  Subsequently 
  the 
  

   statement 
  was 
  repeated, 
  but 
  afterwards 
  it 
  was 
  recollected 
  that 
  the 
  shell 
  liad 
  been 
  

   purchased 
  in 
  Kingston, 
  where 
  the 
  steamers 
  stop 
  on 
  theii- 
  homeward 
  voyage. 
  

   JUNE, 
  1852. 
  26 
  

  

  