﻿98 
  ON 
  THE 
  NAIADES, 
  

  

  cies. 
  1 
  know 
  of 
  no 
  other 
  species 
  which 
  has 
  its 
  lateral 
  teeth 
  so 
  much 
  

   elevated, 
  following, 
  as 
  they 
  do, 
  the 
  widened 
  margin 
  of 
  the 
  valve. 
  The 
  

   cardinal 
  teeth 
  are 
  generally 
  double 
  in 
  the 
  left 
  valve, 
  but 
  not 
  always. 
  

   They 
  will 
  always 
  be 
  found 
  to 
  be 
  compressed 
  in 
  both 
  valves, 
  and 
  gene- 
  

   rally 
  more 
  elevated 
  in 
  the 
  right. 
  The 
  nacre 
  is 
  so 
  very 
  thin 
  as 
  to 
  be 
  

   diaphanous, 
  and 
  the 
  play 
  of 
  iridescent 
  colours 
  is 
  very 
  beautiful. 
  As 
  

   the 
  individual 
  advances 
  in 
  age 
  the 
  marks 
  of 
  growth 
  form 
  large 
  wrin- 
  

   kles, 
  and 
  it 
  then 
  becomes 
  more 
  cylindrical. 
  

  

  Unio 
  Kirtlandianus. 
  Plate 
  XIV. 
  fig. 
  41. 
  

  

  Testa 
  subrotundd, 
  compressd 
  ; 
  valvulis 
  crassis 
  ; 
  natibus 
  subprominentibus 
  ; 
  epi- 
  

   dermide 
  circa 
  nates 
  luted, 
  juxta 
  mar 
  ginem 
  fused 
  ; 
  radiis 
  interruptis 
  ; 
  dentibus 
  

   cardinalibus 
  subcrassis, 
  lateralibus 
  subcurvis 
  brevibusque 
  ; 
  margaritd 
  alba 
  et 
  iri- 
  

   descente. 
  

  

  Shell 
  rather 
  round, 
  compressed 
  ; 
  valves 
  thick 
  ; 
  beaks 
  somewhat 
  elevated 
  ; 
  epidermis 
  

   yellowish 
  about 
  the 
  beaks, 
  brown 
  towards 
  the 
  margin 
  ; 
  rays 
  interrupted 
  ; 
  cardinal 
  teeth 
  

   rather 
  thick 
  ; 
  lateral 
  teeth 
  short 
  and 
  slightly 
  curved 
  ; 
  nacre 
  pearly 
  white 
  and 
  iridescent. 
  

  

  Hab. 
  Mahoning, 
  Ohio. 
  J. 
  P. 
  Kirtland, 
  M.D. 
  

  

  My 
  Cabinet. 
  

  

  Cabinet 
  of 
  P. 
  H. 
  Nicklin. 
  

  

  Diam. 
  1, 
  Length 
  2, 
  Breadth 
  2*3 
  inches. 
  

  

  Shell 
  rather 
  round, 
  compressed 
  ; 
  substance 
  of 
  the 
  shell 
  thick, 
  some- 
  

   what 
  thinner 
  behind 
  ; 
  beaks 
  rather 
  elevated 
  ; 
  ligament 
  rather 
  short 
  and 
  

   thick; 
  epidermis 
  wrinkled, 
  dark 
  brown, 
  smooth 
  and 
  yellowish 
  in 
  the 
  

   region 
  of 
  the 
  beaks 
  ; 
  interrupted 
  rays 
  pass 
  from 
  the 
  beaks 
  and 
  are 
  very 
  

   visible 
  over 
  the 
  umbones, 
  but 
  are 
  lost 
  in 
  the 
  wrinkles 
  before 
  they 
  reach 
  

   the 
  margin 
  ; 
  cardinal 
  teeth 
  rather 
  thick 
  ; 
  lateral 
  teeth 
  short, 
  thick 
  and 
  

   slightly 
  curved 
  ; 
  posterior 
  and 
  anterior 
  cicatrices 
  both 
  distinct 
  ; 
  dorsal 
  

   cicatrices 
  situated 
  on 
  the 
  under 
  side 
  of 
  the 
  cardinal 
  teeth 
  ; 
  cavity 
  of 
  

   the 
  shell 
  flat 
  and 
  shallow 
  ; 
  cavity 
  of 
  the 
  beaks 
  rather 
  deep 
  and 
  angu- 
  

   lated 
  ; 
  nacre 
  pearly 
  white 
  and 
  iridescent. 
  

  

  Remarks. 
  — 
  I 
  owe 
  this 
  new 
  species 
  to 
  the 
  kindness 
  of 
  Dr 
  Kirtland 
  of 
  

  

  