﻿PROPAGATION 
  OF 
  FRESH-WATER 
  MUSSELS. 
  47 
  

  

  water. 
  This 
  is 
  a 
  noteworthy 
  contrast 
  between 
  young 
  and 
  adult 
  as 
  

   to 
  habits 
  and 
  habitat. 
  

  

  In 
  my 
  investigations 
  upon 
  the 
  juveniles 
  I 
  have 
  not 
  found 
  the 
  early 
  

   stages 
  as 
  uncommon 
  as 
  the 
  literature 
  led 
  me 
  to 
  expect 
  (Lefevre 
  and 
  

   Curtis, 
  1912, 
  p. 
  177). 
  The 
  clammers 
  of 
  the 
  Mississippi 
  River 
  seem 
  

   to 
  be 
  familiar 
  with 
  them, 
  reporting 
  that 
  they 
  often 
  bring 
  them 
  up 
  

   with 
  the 
  "spider 
  web 
  attached," 
  referring 
  to 
  the 
  byssus 
  threads. 
  

   Their 
  small 
  size 
  makes 
  them 
  less 
  conspicuous, 
  and 
  special 
  apparatus 
  

   is 
  required 
  for 
  collecting 
  them. 
  In 
  1912 
  I 
  found 
  about 
  400 
  juveniles 
  

   imder 
  20 
  mm., 
  exclusive 
  of 
  Plagiola 
  donaciformis, 
  and 
  comprising 
  25 
  

   species. 
  

  

  Among 
  the 
  Quadrulas 
  I 
  have 
  not 
  found 
  so 
  great 
  a 
  difference, 
  as 
  a 
  

   rule, 
  in 
  the 
  habitat 
  of 
  juvenile 
  and 
  adult 
  as 
  Isely 
  (1911) 
  has 
  reported 
  

   for 
  the 
  Lampsilinae 
  (Ortmann). 
  However, 
  in 
  species 
  which 
  show 
  

   marked 
  differences 
  between 
  juvenile 
  and 
  adult 
  it 
  is 
  quite 
  evident 
  

   that 
  in 
  any 
  scheme 
  of 
  propagation 
  which 
  would 
  carry 
  the 
  young 
  

   through 
  this 
  stage 
  special 
  consideration 
  must 
  be 
  given 
  this 
  period 
  of 
  

   the 
  life 
  history. 
  

  

  