﻿44 
  MUSSEL 
  RESOURCES 
  OF 
  THE 
  ILLINOIS 
  RIVER. 
  

  

  account 
  of 
  its 
  resemblance 
  to 
  L. 
  ventricosa 
  it 
  is 
  often 
  called 
  the 
  "little 
  

   pocketbook." 
  Found 
  gravid 
  June 
  27 
  and 
  July 
  4. 
  

  

  34. 
  Deer-toe, 
  Plagiola 
  elegans 
  (Lea). 
  — 
  This 
  beautiful 
  species 
  is 
  

   found 
  in 
  small 
  quantities 
  throughout 
  the 
  entire 
  river. 
  It 
  is 
  hardly 
  

   considered 
  a 
  commercial 
  shell, 
  but 
  the 
  larger 
  and 
  thicker 
  examples 
  

   are 
  often 
  seen 
  in 
  the 
  mussel 
  camps 
  and 
  piles 
  along 
  the 
  shore. 
  The 
  

   length 
  of 
  the 
  largest 
  shell 
  of 
  tliis 
  species 
  found 
  during 
  the 
  survey 
  was 
  

   2f 
  inches 
  (70 
  mm.). 
  Some 
  examples, 
  particularly 
  from 
  those 
  por- 
  

   tions 
  of 
  the 
  river 
  having 
  soft 
  mud 
  bottoms, 
  are 
  greatly 
  elongated 
  

   posteriorly, 
  and 
  others 
  bear 
  a 
  strong 
  resemblance 
  to 
  P. 
  donaciformis. 
  

  

  There 
  are 
  two 
  forms 
  of 
  elegans 
  found 
  in 
  several 
  of 
  the 
  mussel 
  beds 
  

   of 
  the 
  Ilhnois, 
  particularly 
  noticeable 
  at 
  Peoria. 
  The 
  common 
  form 
  

   is 
  the 
  more 
  abundant 
  and 
  compares 
  favorably 
  with 
  the 
  species 
  in 
  the 
  

   collection 
  of 
  the 
  Unionidse 
  at 
  the 
  Bureau 
  of 
  Fisheries 
  and 
  with 
  those 
  

   found 
  in 
  the 
  Maumee 
  and 
  Wabash 
  Rivers. 
  The 
  other 
  form 
  is 
  pro- 
  

   portionately 
  more 
  inflated, 
  and 
  has 
  brownish 
  epidermis, 
  darker 
  pos- 
  

   teriorly, 
  Avith 
  dark 
  capillary 
  lines. 
  The 
  pseudocardinal 
  teeth 
  are 
  

   heavy 
  and 
  curved; 
  the 
  laterals 
  are 
  broad 
  and 
  striate. 
  The 
  nacre 
  is 
  

   pink. 
  The 
  truncated 
  shape 
  gives 
  it 
  somewhat 
  the 
  appearance 
  of 
  

   Truncilla 
  triquetra 
  (Rafinesque). 
  Some 
  fine 
  examples 
  were 
  found 
  

   near 
  the 
  upper 
  bridge, 
  at 
  Peoria, 
  111., 
  June 
  27. 
  

  

  35. 
  Butterfly, 
  Plagiola 
  securis 
  (Lea). 
  — 
  The 
  butterfly, 
  or 
  securis, 
  

   is 
  not 
  a 
  common 
  species 
  in 
  this 
  river, 
  although 
  many 
  of 
  the 
  beds 
  

   could 
  be 
  made 
  to 
  yield 
  productively 
  by 
  propagation. 
  On 
  account 
  of 
  

   its 
  flatter 
  shape 
  and 
  proportionally 
  hghter 
  weight, 
  the 
  male 
  sheU 
  is 
  

   more 
  valuable 
  for 
  commercial 
  purposes 
  than 
  the 
  female. 
  

  

  36. 
  Missouri 
  niggerhead, 
  Ohovaria 
  ellipsis 
  (Lea). 
  — 
  This 
  species 
  

   is 
  comparatively 
  rare 
  in 
  the 
  Illinois 
  VaUey, 
  but 
  some 
  examples 
  were 
  

   found 
  from 
  Peoria 
  Lake 
  to 
  the 
  mouth. 
  This 
  shell 
  has 
  a 
  velvety 
  

   epidermis 
  and 
  a 
  good 
  pearly 
  nacre 
  and 
  furnishes 
  good 
  button 
  mate- 
  

   rial. 
  The 
  ellipsis 
  appears 
  to 
  be 
  closely 
  related 
  to 
  higginsii. 
  

  

  37. 
  Paper-shell, 
  Lampsilis 
  Isevissima 
  (Lesi). 
  — 
  This 
  shell 
  is 
  fairly 
  

   common 
  in 
  the 
  river, 
  and 
  at 
  the 
  present 
  time 
  has 
  no 
  economic 
  value. 
  

   In 
  nearly 
  every 
  example 
  examined 
  at 
  Beardstown 
  and 
  a 
  few 
  other 
  

   places, 
  this 
  mussel 
  was 
  more 
  or 
  less 
  diseased 
  at 
  or 
  near 
  the 
  tips 
  or 
  

   posterior 
  end, 
  due 
  to 
  parasitic 
  infection. 
  

  

  38. 
  Paper-shell, 
  Lampsilis 
  gracilis 
  (Barnes). 
  — 
  This 
  mussel 
  resem- 
  

   bles 
  the 
  preceding 
  species. 
  The 
  shell 
  is 
  thin 
  and 
  has 
  no 
  commercial 
  

   value, 
  though 
  the 
  meats 
  or 
  soft 
  parts 
  are 
  used 
  occasionally 
  for 
  fish 
  

   bait. 
  Found 
  gravid 
  June 
  27. 
  

  

  39. 
  Pink 
  Heel-splitter, 
  Lampsilis 
  alata 
  (Say). 
  — 
  This 
  species 
  is 
  

   fairly 
  common 
  and 
  is 
  found 
  mostly 
  on 
  mud 
  bottoms. 
  It 
  has 
  no 
  

   commercial 
  value. 
  One 
  of 
  our 
  examples, 
  taken 
  at 
  Hardin, 
  is 
  thick 
  

   enough 
  for 
  manufacturing 
  purposes 
  and 
  has 
  a 
  good 
  white 
  nacre. 
  

  

  