﻿GROWTH 
  AND 
  MIGRATIOlSr 
  OF 
  FEESH-WATER 
  MUSSELS. 
  

  

  15 
  

  

  Table 
  8. 
  — 
  Rate 
  of 
  Growth 
  by 
  Species. 
  

  

  [Note.— 
  This 
  table 
  shows 
  species 
  not 
  mentioned 
  in 
  other 
  tabulations, 
  because 
  the 
  number 
  of 
  individuals 
  

   was 
  too 
  small 
  for 
  comparative 
  study. 
  The 
  records 
  are 
  useful 
  as 
  indicative 
  ot 
  wJiat 
  may 
  be 
  expected 
  from 
  

   those 
  species. 
  The 
  Quadrulae 
  here 
  listed 
  are 
  given 
  because 
  of 
  their 
  use 
  in 
  plate 
  figures!] 
  

  

  Speci- 
  

   men 
  

   No. 
  

  

  109 
  

   113 
  

   111 
  

   114 
  

  

  281* 
  

  

  564* 
  

  

  413* 
  

  

  430 
  

  

  431 
  

  

  XI 
  

  

  X 
  

  

  H* 
  

  

  566* 
  

   650 
  

   495 
  

   V 
  

   LI 
  

  

  Species. 
  

  

  grandis 
  (floater). 
  

   ..do 
  

  

  .do. 
  

   .do. 
  

  

  Q,. 
  undulata 
  ((hree-ridge)... 
  

   Q. 
  lachrymosa 
  (maple-leaf). 
  

  

  .do. 
  

  

  T. 
  tubereulata 
  (buckhorn, 
  pistol-grip). 
  

  

  .do. 
  

  

  L. 
  

  

  gracilis 
  (paper-shell), 
  

   .do 
  

  

  .do. 
  

  

  L. 
  anodontoides 
  (yellow 
  sand-shell).. 
  

   ...do 
  

  

  U. 
  

  

  .do 
  

  

  tetralasmus 
  . 
  

   .do 
  

  

  Time. 
  

  

  AVeight. 
  

  

  /When 
  planted.. 
  

  

  \1 
  year 
  later 
  

  

  (When 
  planted.. 
  

  

  \1 
  yearlaler 
  

  

  iWhenpIanted.. 
  

  

  \1 
  year 
  later 
  

  

  (When 
  planted.. 
  

  

  U 
  yearlater 
  

  

  (When 
  plan 
  ted.. 
  

   .jl 
  year 
  and 
  3 
  

   [ 
  months 
  later. 
  

   (Wlien 
  plan 
  ted.. 
  

   h 
  year 
  and 
  3 
  

   [ 
  months 
  later. 
  

   /TAHien 
  planted.. 
  

  

  \1 
  3-ear 
  later 
  

  

  (Whenplanted.. 
  

   il 
  year 
  and 
  3 
  

   I 
  months 
  later. 
  

   fWTien 
  planted 
  . 
  

  

  \1 
  yearlater 
  

  

  I 
  When 
  planted.. 
  

   \3 
  months 
  later. 
  . 
  

   / 
  VvTien 
  planted. 
  , 
  

   (3 
  months 
  later. 
  , 
  

  

  Whenplanted.. 
  

  

  1 
  year 
  and 
  3 
  

   mouths 
  later. 
  

  

  When 
  planted. 
  . 
  

   \3 
  mouths 
  later. 
  . 
  

   /Whenplanted.. 
  

  

  \1 
  yearlater 
  

  

  i 
  When 
  planted., 
  

  

  tl 
  yearlater 
  

  

  (Whenplanted., 
  

  

  tl 
  year 
  later 
  

  

  I 
  Wlien 
  planted. 
  

   \1 
  year 
  later 
  

  

  Grams. 
  

   143 
  

   193 
  

   144 
  

  

  192 
  

  

  211 
  

  

  209 
  

  

  2S1.5 
  

  

  320 
  

  

  16.6 
  

  

  51 
  

  

  5 
  

   20.5 
  

  

  18 
  

   128 
  

   138 
  

  

  470 
  

   489 
  

  

  11 
  

  

  29 
  

  

  13 
  

  

  55 
  

  

  22.5 
  

  

  84 
  

  

  97 
  

   116 
  

   125 
  

   138 
  

   180 
  

   1S6 
  

  

  25 
  

  

  30 
  

  

  31 
  

  

  43 
  

  

  Length. 
  

  

  Mm. 
  

   120 
  

   127 
  

   120 
  

   124 
  

   132 
  

   139 
  

   140 
  

   142 
  

  

  40 
  

  

  65 
  

  

  22 
  

   41 
  

  

  27 
  

   42 
  

   87 
  

   90 
  

  

  136 
  

   136.5 
  

  

  51 
  

  

  69 
  

  

  55 
  

  

  82 
  

  

  63 
  

  

  97 
  

  

  93 
  

  

  97.5 
  

   103 
  

   106 
  

   110 
  

   111 
  

  

  65 
  

  

  71 
  

  

  70 
  

  

  Height. 
  Breadth. 
  

  

  Mm. 
  

   63 
  

   66 
  

   62 
  

   65 
  

   72 
  

   74 
  

   82 
  

   82 
  

   27 
  

   41 
  

  

  17 
  

   32 
  

  

  22 
  

   35 
  

   56 
  

  

  58 
  

  

  76 
  

  

  76.5 
  

  

  26 
  

  

  35 
  

  

  27 
  

  

  44 
  

  

  32 
  

  

  50 
  

  

  49 
  

  

  48 
  

  

  49 
  

  

  51 
  

  

  51.5 
  

  

  33 
  

  

  36 
  

  

  35 
  

  

  37 
  

  

  Mm. 
  

   41 
  

   45 
  

   41 
  

   45 
  

   48 
  

   52 
  

   53 
  

   54 
  

   16 
  

   25 
  

  

  10 
  

   20 
  

  

  13 
  

   19 
  

   31 
  

   32 
  

  

  50 
  

  

  50 
  

  

  14 
  

  

  20.5 
  

  

  18 
  

  

  28 
  

  

  19 
  

  

  33 
  

  

  34 
  

  

  35.5 
  

  

  37 
  

  

  37.5 
  

  

  43 
  

  

  43 
  

  

  20 
  

  

  22 
  

  

  22 
  

  

  23 
  

  

  DISCUSSION 
  OF 
  DATA. 
  

  

  The 
  results 
  set 
  forth 
  m 
  the 
  tables 
  given 
  above 
  speak 
  for 
  them- 
  

   selves 
  and 
  need 
  no 
  extensive 
  explanation. 
  

  

  One 
  strildng 
  fact 
  is 
  the 
  cessation 
  of 
  growth 
  during 
  the 
  winter 
  

   months 
  of 
  the 
  Chikaskia 
  specimens, 
  especially 
  in 
  table 
  3. 
  There 
  are 
  

   a 
  number 
  of 
  cases 
  in 
  my 
  field 
  records 
  where 
  a 
  loss 
  is 
  shown 
  m 
  weight 
  

   for 
  the 
  six 
  months 
  from 
  late 
  September 
  to 
  early 
  AprU, 
  although 
  in 
  

   general 
  they 
  hold 
  their 
  own. 
  It 
  has 
  been 
  my 
  observation 
  for 
  

   several 
  years 
  that 
  the 
  Cliikaskia 
  mussels, 
  in 
  the 
  shallow 
  water 
  at 
  least, 
  

   burrow 
  down 
  into 
  the 
  sand 
  in 
  late 
  October 
  and 
  become 
  abundant 
  

   again 
  in 
  late 
  April. 
  

  

  For 
  undulata 
  (three-ridge), 
  I 
  have 
  given 
  rather 
  complete 
  averages 
  

   of 
  weight, 
  and 
  comparisons 
  of 
  rate 
  of 
  growth 
  according 
  to 
  size 
  in. 
  

   tables 
  5-8. 
  From 
  tables 
  1 
  and 
  2 
  (all 
  lot 
  D), 
  I 
  find 
  the 
  averages 
  given 
  

   below 
  for 
  the 
  four 
  species 
  named: 
  Undulata 
  (three-ridge), 
  12 
  speci- 
  

   mens; 
  lachrymosa 
  (maple-leaf), 
  7 
  specimens; 
  yustulosa 
  (warty- 
  

   back, 
  pimple-back), 
  8 
  specimens; 
  ruhiginosa, 
  5 
  specimens. 
  From 
  

  

  