﻿23 
  

  

  ARTICLE 
  II 
  

  

  Observations 
  on 
  the 
  Naiades 
  ; 
  and 
  Descriptions 
  of 
  New 
  Species 
  of 
  thai, 
  

   and 
  other 
  Families. 
  By 
  Isaac 
  Lea. 
  Read 
  before 
  the 
  American 
  

   Philosophical 
  Society 
  March 
  16, 
  1832. 
  

  

  PRELIMINARY 
  REMARKS. 
  

  

  In 
  presenting 
  myself 
  again 
  before 
  the 
  Society 
  with 
  a 
  new 
  memoir 
  in 
  

   that 
  department 
  of 
  conchology 
  which 
  has 
  so 
  much 
  engaged 
  my 
  atten- 
  

   tion 
  for 
  some 
  years, 
  an 
  apology 
  would 
  seem 
  almost 
  necessary. 
  My 
  

   zeal 
  and 
  love 
  for 
  the 
  science 
  generally 
  will, 
  I 
  trust, 
  be 
  sufficient 
  for 
  

   ray 
  present 
  intrusion 
  on 
  its 
  time. 
  

  

  The 
  family 
  Naiades 
  seems 
  to 
  have 
  excited 
  very 
  little 
  interest 
  with 
  

   the 
  older 
  writers 
  on 
  natural 
  history, 
  and 
  not 
  much 
  more 
  among 
  mo- 
  

   dern 
  zoologists 
  until 
  within 
  the 
  present 
  century. 
  

  

  The 
  progress 
  of 
  general 
  knowledge, 
  and 
  the 
  improvements 
  in 
  the 
  

   mechanic 
  arts, 
  have 
  recently 
  been 
  greatly 
  accelerated, 
  and 
  the 
  disco- 
  

   veries 
  and 
  improvements 
  in 
  the 
  study 
  of 
  natural 
  science, 
  have 
  gone 
  on 
  

   " 
  pari 
  passu" 
  with 
  them 
  ; 
  and 
  we 
  have 
  every 
  reason 
  to 
  believe 
  that 
  the 
  

   momentum 
  which 
  they 
  have 
  acquired 
  will" 
  not 
  be 
  diminished, 
  for, 
  to 
  

   use 
  the 
  words 
  of 
  one 
  of 
  the 
  most 
  successful 
  writers 
  of 
  the 
  present 
  day. 
  

   " 
  there 
  is 
  growing 
  up 
  an 
  enlightened 
  public 
  opinion" 
  which 
  no 
  power 
  

   is 
  likely 
  to 
  arrest, 
  and 
  which 
  must 
  carry 
  us 
  far 
  towards 
  a 
  perfect 
  state 
  

  

  