﻿88 
  ON 
  THE 
  NAIADES, 
  

  

  Unio 
  ligdmentina. 
  The 
  specimen 
  in 
  the 
  Garden 
  of 
  Plants 
  is 
  the 
  

   U. 
  crassus 
  of 
  Say. 
  

  

  Unio 
  obliqua. 
  in 
  the 
  same 
  collection 
  is 
  the 
  U. 
  undatus 
  of 
  Barnes. 
  

  

  Unio 
  retusa. 
  This 
  is 
  the 
  U. 
  torsus 
  (Rafinesque). 
  The 
  locality 
  given 
  

   is 
  Nova 
  Scotia 
  ; 
  the 
  correctness 
  of 
  which 
  I 
  douht 
  much. 
  It 
  is, 
  as 
  yet, 
  

   known 
  to 
  exist 
  only 
  in 
  our 
  western 
  waters. 
  

  

  Unio 
  rarisulcata. 
  The 
  specimen 
  in 
  the 
  Garden 
  of 
  Plants 
  is 
  the 
  

   complanalus 
  (Soland.), 
  purpureus 
  of 
  Say. 
  

  

  Unio 
  coarctata. 
  The 
  specimen 
  in 
  the 
  collection 
  of 
  the 
  Duke 
  de 
  

   Rivoli 
  is 
  the 
  complanatus 
  (Soland. 
  ). 
  The 
  observation 
  of 
  Lamarck, 
  that 
  

   " 
  it 
  is 
  the 
  analogue 
  of 
  our 
  U. 
  margaritifera," 
  (he 
  ought 
  to 
  have 
  said 
  

   elongata, 
  for 
  he 
  does 
  not 
  use 
  the 
  name 
  of 
  margaritifera) 
  must 
  be 
  an 
  

   error. 
  The 
  American 
  shell, 
  described 
  by 
  Barnes 
  as 
  Masmodonta 
  ar- 
  

   cuata, 
  is 
  the 
  unquestionable 
  analogue 
  of 
  the 
  true 
  Mya 
  margaritifera 
  

   (Linn.), 
  and 
  a 
  very 
  different 
  shell, 
  not 
  having 
  a 
  lateral 
  tooth, 
  and 
  

   belonging 
  to 
  Schumacker's 
  genus 
  Margaritana 
  (Say's 
  Alasmodonta). 
  

  

  Unio 
  purpurascens. 
  This 
  is 
  also 
  a 
  complanatus, 
  in 
  the 
  museum 
  of 
  

   the 
  Garden 
  of 
  Plants. 
  

  

  Unio 
  radiata. 
  The 
  specimen 
  at 
  the 
  Garden 
  of 
  Plants 
  is 
  the 
  true 
  

   radiatus. 
  The 
  Unio 
  ochraceus 
  (Say), 
  given 
  as 
  a 
  synonym 
  e, 
  is 
  a 
  very 
  

   distinct 
  species. 
  

  

  Unio 
  brevialis. 
  The 
  specimen 
  at 
  the 
  Garden 
  of 
  Plants 
  resembles 
  so 
  

   closely 
  the 
  U. 
  littoralis, 
  that 
  I 
  am 
  induced 
  to 
  believe 
  it 
  never 
  came 
  

   from 
  the 
  Isle 
  of 
  France, 
  and 
  that 
  it 
  is 
  of 
  European 
  origin. 
  That 
  in 
  

   Baron 
  de 
  Ferussac's 
  cabinet 
  is 
  certainly 
  an 
  old 
  littoralis. 
  The 
  shell 
  

   figured 
  by 
  Crouch, 
  under 
  the 
  name 
  brevialis, 
  is 
  entirely 
  distinct. 
  

  

  Unio 
  rhombula. 
  The 
  specimen 
  now 
  in 
  the 
  cabinet 
  of 
  the 
  Duke 
  de 
  

   Rivoli* 
  is 
  a 
  young 
  and 
  bad 
  specimen 
  of 
  the 
  complanatus, 
  and 
  certainly 
  

   from 
  the 
  United 
  States, 
  and 
  not 
  Senegal. 
  Var. 
  b, 
  in 
  the 
  cabinet 
  of 
  

   Valenciennes, 
  I 
  did 
  not 
  see. 
  

  

  ater, 
  under 
  the 
  name 
  of 
  U. 
  lugubris, 
  alleging 
  that 
  the 
  name 
  ater 
  is 
  " 
  preoccupied 
  by 
  Nilsson 
  

   for 
  a 
  very 
  distinct 
  species." 
  Mr 
  S. 
  does 
  not 
  seem 
  to 
  be 
  aware, 
  that 
  Nilsson's 
  ater 
  is 
  only 
  a 
  

   variety 
  of 
  U. 
  Batava, 
  of 
  Maton 
  and 
  Racket 
  ; 
  and, 
  therefore, 
  could 
  not 
  affect 
  my 
  claim. 
  We 
  

   must 
  both 
  yield 
  to 
  the 
  prior 
  claim 
  of 
  Lamarck. 
  

  

  * 
  I 
  ought 
  to 
  say 
  that 
  the 
  Duke 
  keeps 
  the 
  cabinet 
  of 
  Lamarck 
  intact, 
  as 
  much 
  as 
  possible, 
  and, 
  

   therefore, 
  the 
  shells 
  quoted 
  may 
  be 
  relied 
  on 
  as 
  being 
  the 
  same 
  as 
  described 
  by 
  Lamarck. 
  

  

  