﻿MUSSEL 
  RESOURCES 
  OF 
  THE 
  ILLINOIS 
  RIVER. 
  ' 
  9 
  

  

  and 
  development 
  of 
  these 
  species, 
  although 
  several 
  other 
  genera 
  occur 
  

   in 
  small 
  quantities. 
  The 
  principal 
  commercial 
  species 
  (which 
  are 
  

   found 
  in 
  larger 
  numbers 
  than 
  all 
  the 
  other 
  kinds 
  combined) 
  are 
  the 
  

   blue 
  point 
  (Q. 
  undulata), 
  washboard 
  {Q. 
  Tieros), 
  warty-back 
  (Q. 
  pus- 
  

   tulosa), 
  three-ridge 
  {Q. 
  plicata), 
  pig-toe 
  {Q. 
  undata), 
  and 
  muckets 
  

   (L. 
  ligamentina 
  and 
  luteola). 
  

  

  The 
  Illinois 
  River 
  shells 
  are 
  generally 
  perfect 
  specimens, 
  and 
  

   seldom 
  eroded 
  at 
  the 
  beaks; 
  and, 
  for 
  the 
  class, 
  the 
  product 
  is 
  excep- 
  

   tionally 
  good 
  button 
  material. 
  A 
  peculiar 
  feature, 
  however, 
  of 
  the 
  

   shells, 
  particularly 
  noticeable 
  in 
  the 
  lower 
  stretches, 
  is 
  their 
  gradual 
  

   reduction 
  in 
  size 
  as 
  we 
  go 
  down 
  the 
  river. 
  From 
  the 
  upper 
  limits 
  of 
  

   shell 
  production 
  to 
  Beardstown, 
  the 
  shells 
  are 
  of 
  the 
  average 
  size 
  of 
  

   similar 
  species 
  found 
  in 
  other 
  rivers 
  of 
  the 
  Mississippi 
  Basin, 
  but 
  

   from 
  Beardstown 
  to 
  Hardin, 
  a 
  distance 
  of 
  70 
  miles, 
  they 
  become 
  

   gradually 
  smaller, 
  thence 
  slightly 
  larger 
  to 
  near 
  the 
  mouth 
  at 
  Grafton. 
  

   Even 
  old 
  shells 
  taken 
  from 
  protected 
  places 
  show 
  this 
  character. 
  

   What 
  causes 
  this 
  condition 
  is 
  not 
  very 
  evident. 
  It 
  can 
  hardly 
  be 
  due 
  

   to 
  the 
  lesser 
  quantity 
  of 
  food 
  material 
  coming 
  down 
  the 
  river 
  from 
  

   the 
  drainage 
  canal, 
  or 
  to 
  any 
  particular 
  change 
  of 
  bottom. 
  The 
  

   quality 
  of 
  these 
  smaller 
  shells 
  is 
  fully 
  as 
  good 
  if 
  not 
  better 
  than 
  those 
  

   of 
  the 
  upper 
  districts. 
  

  

  SCIENTIFIC 
  AND 
  COMMON 
  NAMES. 
  

  

  The 
  table 
  of 
  scientific 
  and 
  common 
  names 
  of 
  the 
  shells 
  used 
  in 
  this 
  

   report 
  and 
  given 
  herewith 
  is 
  for 
  the 
  convenience 
  of 
  those 
  who 
  may 
  

   desire 
  to 
  use 
  the 
  data 
  for 
  comparison. 
  The 
  nomenclature 
  of 
  Simp- 
  

   son, 
  ** 
  with 
  but 
  few 
  exceptions, 
  is 
  used, 
  although 
  many 
  of 
  the 
  recent 
  

   changes 
  recommended 
  by 
  Dr. 
  Ortmann 
  and 
  others 
  will 
  doubtless 
  

   prove 
  to 
  be 
  well 
  founded. 
  

  

  List 
  op 
  Common 
  and 
  Scientific 
  Names. 
  

  

  Common 
  name. 
  Scientific 
  name. 
  

  

  Purple 
  warty-back 
  Quadrula 
  granifera 
  (Lea) 
  . 
  

  

  Quaclrula 
  tuberculata 
  (Raf.). 
  

   Niggerhead 
  Quadrula 
  ebena 
  (Lea) 
  . 
  

  

  Quadrula 
  pyramidata 
  (Lea). 
  

  

  Quadrula 
  plena 
  (Lea). 
  

  

  Quadrula 
  solida 
  (Lea). 
  

  

  Quadrula 
  coccinea 
  (Con.). 
  

  

  Ohio 
  River 
  pig-toe 
  Quadrula 
  obliqua 
  (Lam.). 
  

  

  Pig-toe 
  Quadrula 
  trigona 
  (Lea) 
  . 
  

  

  Wabash 
  pig-toe 
  Quadrula 
  rubiginosa 
  (Lea) 
  . 
  

  

  Two-homed 
  pocketbook 
  Quadrula 
  pustulata 
  (Lea). 
  

  

  Warty 
  -back 
  Quadrula 
  pustulosa 
  (Lea) 
  . 
  

  

  Quadrula 
  fragosa 
  (Con.). 
  

  

  a 
  Simpson, 
  Charles 
  T.: 
  Synopsis 
  of 
  tiie 
  Naiades, 
  or 
  pearly 
  fresh-water 
  mussels. 
  Proceedings 
  U. 
  S. 
  

   National 
  Museum, 
  vol. 
  xxn, 
  no. 
  1205, 
  1900, 
  p. 
  501-1044. 
  

  

  