﻿20 
  (iROWTH 
  AND 
  MIGRATION 
  OF 
  FRESH- 
  WATER 
  MUSSELS. 
  

  

  form. 
  In 
  all 
  my 
  reclaiming 
  work 
  in 
  the 
  Shoofly, 
  which 
  amounted 
  

   to 
  about 
  10 
  hours' 
  actual 
  huntmg 
  and 
  collecting 
  on 
  three 
  different 
  

   days, 
  I 
  secured 
  only 
  one 
  specimen 
  that 
  may 
  be 
  said 
  to 
  be 
  off 
  the 
  

   planting 
  plot; 
  this 
  was 
  no. 
  141, 
  found 
  15 
  feet 
  from 
  plot 
  D. 
  

  

  CHIKASKIA. 
  

  

  In 
  the 
  Chikaskia 
  lot 
  E 
  gave 
  results 
  similar 
  to 
  D. 
  The 
  Chikaskia 
  

   River 
  specimens 
  were 
  disturbed 
  somewhat 
  by 
  curious 
  people, 
  and 
  for 
  

   this 
  reason 
  proportional 
  figures 
  can 
  not 
  be 
  emphasized. 
  The 
  inclosure 
  

   for 
  lot 
  E 
  (p. 
  9) 
  was 
  rather 
  small, 
  but 
  there 
  was 
  ample 
  chance 
  for 
  

   movement. 
  The 
  results 
  in 
  this 
  instance 
  substantiate 
  what 
  I 
  have 
  

   often 
  noticed 
  in 
  field 
  work, 
  namely, 
  that 
  the 
  mussels, 
  especially 
  

   Quadrulse 
  and 
  related 
  species, 
  are 
  unable 
  to 
  help 
  themselves 
  if 
  con- 
  

   ditions 
  become 
  unfavorable, 
  but, 
  on 
  the 
  other 
  hand, 
  the 
  power 
  to 
  

   endure 
  these 
  unfavorable 
  conditions 
  is 
  remarkable. 
  

  

  Since 
  the 
  Chikaskia 
  is 
  a 
  fairly 
  swift 
  stream, 
  the 
  lower 
  end 
  of 
  the 
  

   inclosure 
  was 
  undermined, 
  making 
  escape 
  easy, 
  while 
  a 
  sand 
  bar 
  was 
  

   formed 
  across 
  the 
  upper 
  portion. 
  Two-thirds 
  of 
  the 
  mussels 
  were 
  

   caught 
  in 
  the 
  drift 
  bar 
  and 
  when 
  I 
  examined 
  them 
  on 
  September 
  26, 
  

   1910, 
  were 
  helplessly 
  stranded. 
  Conditions 
  of 
  oxygen 
  and 
  food 
  sup- 
  

   ply 
  must 
  have 
  been 
  unfavorable, 
  and 
  as 
  a 
  direct 
  result 
  the 
  summer's 
  

   growth 
  was 
  below 
  the 
  average 
  for 
  lot 
  F. 
  

  

  These 
  stranded 
  specimens 
  were 
  now 
  taken 
  and 
  put 
  in 
  the 
  outer 
  

   corner 
  of 
  the 
  pen, 
  where 
  they 
  could 
  escape 
  under 
  the 
  wu"e 
  net 
  through 
  

   an 
  opening 
  5 
  feet 
  long. 
  Six 
  months 
  later, 
  June 
  22, 
  1911, 
  I 
  again 
  

   exammed 
  lot 
  E. 
  A 
  large 
  number 
  of 
  the 
  specimens 
  were 
  recovered, 
  

   about 
  half 
  being 
  along 
  the 
  wke 
  net 
  uiside, 
  and 
  half 
  along 
  the 
  net 
  

   outside; 
  not 
  a 
  specimen 
  was 
  found 
  over 
  5 
  yards 
  from 
  the 
  pen. 
  

   Clear 
  water 
  and 
  sandy 
  bottom 
  made 
  the 
  finding 
  of 
  specimens 
  easy. 
  

  

  Lot 
  F 
  specimens 
  of 
  the 
  Esch 
  inclosure 
  (p. 
  9) 
  had 
  a 
  good 
  opportu- 
  

   nity 
  for 
  migration; 
  in 
  fact, 
  the 
  mclosure 
  was 
  not 
  needed, 
  as 
  only 
  

   two 
  specknens 
  reached 
  either 
  lower 
  or 
  upper 
  cross 
  fences. 
  One 
  of 
  

   these 
  was 
  a 
  gracilis 
  (paper-shell), 
  and 
  the 
  other 
  a 
  grandis 
  (floater). 
  

   The 
  Quadi'ulse 
  did 
  not 
  come 
  withm 
  25 
  yards 
  of 
  the 
  lower 
  fence. 
  If 
  

   they 
  were 
  placed 
  m 
  water 
  over 
  3 
  feet 
  deep, 
  the 
  migration 
  was 
  slight 
  

   in 
  any 
  case, 
  as 
  far 
  as 
  the 
  Quadrulae 
  were 
  concerned. 
  Those 
  placed 
  in 
  

   water 
  as 
  shallow 
  as 
  1 
  foot 
  moved 
  to 
  deeper 
  water, 
  which 
  was 
  easily 
  

   reached 
  in 
  this 
  case. 
  The 
  Lampsilcs 
  were 
  more 
  active, 
  and 
  the 
  per- 
  

   centage 
  recovered 
  was 
  smaU 
  by 
  comparison. 
  Of 
  the 
  50 
  U. 
  tetralas- 
  

   mus, 
  not 
  a 
  single 
  specimen 
  or 
  shell 
  was 
  found 
  at 
  the 
  first 
  examination, 
  

   September, 
  1910; 
  but 
  in 
  the 
  June, 
  1911, 
  examination, 
  three 
  speci- 
  

   mens 
  were 
  found. 
  I 
  am 
  not 
  able 
  to 
  explain 
  the 
  disappearance 
  of 
  the 
  

   tetrdlasmvs; 
  however, 
  they 
  are 
  great 
  burrowers, 
  and 
  may 
  have 
  

   escaped 
  my 
  extensive 
  digging 
  for 
  them. 
  

  

  