﻿86 
  ON 
  THE 
  NAIADES, 
  

  

  umbonial 
  slope 
  near 
  to 
  the 
  margin, 
  the 
  edges 
  of 
  each 
  growth 
  being 
  there 
  

   dentate. 
  In 
  some 
  specimens 
  this 
  is 
  so 
  strongly 
  marked 
  as 
  to 
  resemble 
  

   a 
  thick 
  cord. 
  The 
  Jlrcxformis, 
  professor 
  T. 
  doubts 
  being 
  in 
  Tennessee 
  

   river. 
  He 
  found 
  it 
  only 
  in 
  the 
  Cumberland. 
  He 
  was, 
  I 
  believe, 
  the 
  

   first 
  person 
  who 
  sent 
  this 
  species 
  to 
  New 
  York 
  and 
  this 
  city. 
  Some 
  

   fine 
  old 
  specimens, 
  recently 
  received 
  from 
  that 
  gentleman, 
  exhibit 
  a 
  

   diameter 
  of 
  a 
  most 
  extraordinary 
  nature, 
  as 
  well 
  also 
  an 
  almost 
  perfect 
  

   flatness 
  of 
  the 
  posterior 
  slope. 
  My 
  oldest 
  specimen, 
  when 
  placed 
  on 
  

   a 
  plane, 
  will 
  rest 
  both 
  on 
  the 
  base 
  and 
  on 
  that 
  slope. 
  The 
  specimen 
  

   figured 
  by 
  me, 
  was 
  not 
  more 
  than 
  two-thirds 
  grown, 
  and 
  was 
  then 
  the 
  

   best 
  specimen 
  I 
  had 
  seen, 
  and 
  I 
  supposed 
  it 
  to 
  be 
  an 
  adult. 
  

  

  OBSERVATIONS 
  ON 
  LAMARCK'S 
  NAIADES. 
  

  

  Having 
  had 
  the 
  opportunity 
  while 
  in 
  Paris 
  recently, 
  to 
  inspect 
  most 
  

   of 
  the 
  cabinets 
  to 
  which 
  Lamarck 
  refers 
  in 
  his 
  description 
  of 
  the 
  

   Naiades, 
  I 
  seized 
  the 
  opportunity 
  to 
  examine 
  the 
  individual 
  specimens 
  

   from 
  which 
  he 
  made 
  his 
  descriptions 
  ; 
  and 
  having 
  made 
  notes 
  on 
  the 
  

   spot, 
  I 
  feel 
  great 
  confidence 
  as 
  to 
  the 
  facts, 
  and 
  trust 
  that 
  my 
  judgment 
  

   as 
  to 
  the 
  decisions 
  on 
  his 
  species 
  will 
  be 
  found 
  to 
  be 
  correct. 
  

  

  In 
  pointing 
  out 
  the 
  errors 
  of 
  this 
  great 
  zoologist, 
  we 
  must 
  not 
  be 
  

   astonished 
  at 
  their 
  number, 
  nor 
  should 
  the 
  slightest 
  shadow 
  fall 
  upon 
  

   his 
  merited 
  and 
  exalted 
  reputation. 
  We 
  should 
  rather 
  think 
  of 
  the 
  

   means 
  within 
  his 
  power, 
  the 
  poverty 
  of 
  the 
  materials 
  with 
  which 
  he 
  

   worked, 
  and 
  above 
  all, 
  the 
  unfortunate 
  ophthalmia 
  which 
  afflicted 
  his 
  

   declining 
  years, 
  and 
  which 
  he 
  deplores 
  in 
  the 
  advertisement 
  of 
  the 
  

   sixth 
  volume 
  of 
  his 
  Hist. 
  Nat. 
  des 
  Animaux 
  sans 
  Vertebres. 
  

  

  TJnio 
  sinuata. 
  This 
  is 
  a 
  true 
  species, 
  but 
  Klein 
  is 
  entitled 
  to 
  the 
  

   name 
  which 
  he 
  gave 
  first 
  to 
  it, 
  viz. 
  crassissima.* 
  It 
  has 
  been 
  consi- 
  

   dered 
  by 
  the 
  conchologists 
  of 
  this 
  country 
  (and 
  I 
  certainly 
  was 
  of 
  the 
  

  

  * 
  See 
  Transactions 
  of 
  the 
  Linnean 
  Society 
  of 
  Bourdeaux, 
  Vol. 
  II. 
  p. 
  42. 
  

  

  