﻿94 
  ON 
  THE 
  NAIADES, 
  

  

  it 
  comes 
  only 
  from 
  the 
  more 
  southern 
  rivers 
  of 
  South 
  America. 
  My 
  

   specimens, 
  and 
  those 
  I 
  saw 
  in 
  Europe, 
  came 
  from 
  the 
  river 
  La 
  Plata. 
  

   It 
  has 
  a 
  peculiar 
  character, 
  which 
  Lamarck 
  does 
  not 
  notice, 
  in 
  the 
  

   deposit 
  of 
  epidermal 
  matter 
  at 
  different 
  stages 
  of 
  growth, 
  with 
  the 
  nacre 
  

   extending 
  in 
  waved 
  lines, 
  generally 
  from 
  one 
  great 
  cicatrix 
  to 
  the 
  other, 
  

   forming 
  curves 
  parallel 
  with 
  the 
  palleal 
  cicatrix. 
  

  

  Anodonta 
  glauca 
  is 
  a 
  distinct 
  species, 
  inhabiting 
  Mexico, 
  and 
  figured 
  

   in 
  a 
  recent 
  number 
  of 
  Humboldt's 
  great 
  work. 
  

  

  Anodonta 
  sinuosa. 
  I 
  saw 
  the 
  specimen 
  described, 
  in 
  Baron 
  de 
  

   Ferussac's 
  cabinet. 
  It 
  is 
  very 
  distinct, 
  and 
  very 
  peculiar 
  in 
  the 
  sinuous 
  

   dorsal 
  line. 
  This 
  species 
  is 
  in 
  my 
  cabinet. 
  

  

  Anodonta 
  Patagonica. 
  This 
  is 
  also 
  a 
  distinct 
  and 
  very 
  rare 
  species. 
  

   The 
  possession 
  of 
  a 
  specimen 
  I 
  owe 
  to 
  the 
  kindness 
  of 
  Mr 
  G. 
  B. 
  

   Sowerby. 
  

  

  Iridina 
  exotica. 
  To 
  Baron 
  de 
  Ferussac 
  I 
  owe 
  the 
  possession 
  of 
  this 
  

   species. 
  It 
  appears 
  to 
  differ 
  from 
  the 
  Nilotica 
  in 
  being 
  tuherculated 
  

   along 
  the 
  dorsal 
  line, 
  which 
  is 
  one 
  of 
  Lamarck's 
  generic 
  characters. 
  

   The 
  Nilotica, 
  which 
  I 
  received 
  from 
  the 
  African 
  traveller 
  Monsieur 
  

   Cailliaud, 
  has 
  no 
  crenulations 
  along 
  the 
  dorsal 
  line, 
  but 
  I 
  have 
  seen 
  

   specimens 
  on 
  which 
  a 
  few 
  could 
  be 
  observed. 
  The 
  Clappertoni 
  of 
  

   Denman 
  is 
  a 
  young 
  Nilotica. 
  

  

  