﻿PEOPAGATIOlSr 
  OF 
  FKESH-WATEE 
  MUSSELS. 
  29 
  

  

  observations 
  covering 
  two 
  successive 
  seasons, 
  the 
  mature 
  glochidia 
  

   were 
  readily 
  obtained, 
  as 
  the 
  majority 
  of 
  adult 
  females 
  examined 
  

   were 
  gravid. 
  An 
  examination 
  on 
  November 
  7 
  of 
  55 
  individuals 
  

   from 
  the 
  same 
  mussel 
  bed 
  yielded 
  no 
  gravid 
  specimens 
  at 
  aU, 
  and 
  

   some 
  50 
  mussels 
  in 
  March 
  and 
  April 
  yielded 
  1 
  gravid 
  specimen 
  only; 
  

   this 
  was 
  found 
  April 
  14, 
  and 
  contained 
  immature 
  glochidia, 
  still 
  

   surrounded 
  by 
  the 
  vitelhne 
  membrane. 
  All 
  the 
  information 
  available 
  

   indicates 
  that 
  the 
  regtdar 
  breeding 
  season 
  is 
  during 
  the 
  autumn, 
  

   cliiefly 
  October, 
  with 
  an 
  extension 
  into 
  the 
  winter 
  months 
  in 
  some 
  

   localities, 
  but 
  that 
  the 
  glochidia 
  are 
  not 
  carried 
  a 
  long 
  period 
  in 
  the 
  

   gills 
  as 
  in 
  the 
  Lampsihnse. 
  Since 
  all 
  tour 
  gills 
  are 
  used 
  as 
  marsupia 
  

   and 
  greatly 
  distended, 
  a 
  long 
  breeding 
  period 
  would 
  seem 
  to 
  be 
  too 
  

   g/eat 
  an 
  interference 
  with 
  the 
  breathing 
  function 
  of 
  the 
  gill. 
  

  

  The 
  productivity 
  of 
  this 
  form 
  is 
  enormous, 
  a 
  single 
  average-sized 
  

   individual 
  in 
  which 
  I 
  estimated 
  the 
  number 
  gave 
  one 
  and 
  a 
  third 
  

   million 
  young. 
  A 
  count 
  was 
  macie 
  of 
  a 
  definite 
  fraction 
  of 
  a 
  marsupial 
  

   chamber 
  in 
  a 
  gill 
  and 
  the 
  total 
  computed 
  from 
  a 
  count 
  of 
  these 
  

   chambers 
  lor 
  the 
  four 
  g.lls, 
  account 
  being 
  taken 
  of 
  difference 
  in 
  size 
  

   in 
  the 
  gills. 
  Simpson 
  (1899) 
  quotes 
  Lea 
  as 
  giving 
  the 
  number 
  of 
  

   young 
  produced 
  as 
  6,000,000. 
  I 
  have 
  not 
  seen 
  the 
  original 
  of 
  this 
  

   statement 
  by 
  Lea, 
  but 
  find 
  another 
  (Lea, 
  1857, 
  p. 
  40) 
  in 
  which 
  he 
  

   gives 
  an 
  estimate 
  of 
  3,000,000 
  or 
  4,000,000 
  as 
  the 
  number 
  produced; 
  

   as 
  he 
  says 
  "probably 
  to 
  the 
  number 
  of 
  3,000,000 
  or 
  4,000,000," 
  he 
  

   may 
  not 
  have 
  made 
  an 
  actual 
  computation. 
  A 
  specimen 
  twice 
  tne 
  

   size 
  of 
  the 
  one 
  I 
  considered, 
  which 
  would 
  be 
  unusually 
  large, 
  would 
  

   hardly 
  have 
  more 
  than 
  3,000,000. 
  From 
  this 
  I 
  suspect 
  that 
  Lea's 
  

   estimate 
  is 
  too 
  Ir'gh. 
  Lefevre 
  and 
  Curtis 
  (1912, 
  p. 
  144) 
  say 
  in 
  regard 
  

   to 
  the 
  breeding 
  period 
  of 
  this 
  species 
  that, 
  finding 
  young 
  embryos 
  in 
  

   May, 
  their 
  observations 
  are 
  not 
  in 
  accord 
  with 
  those 
  of 
  Frierson 
  

   (1904), 
  who 
  found 
  glochidia 
  in 
  January 
  and 
  so 
  concludes 
  that 
  heros 
  

   is 
  an 
  exception 
  to 
  the 
  genus 
  Quadrula 
  and 
  not 
  a 
  summer 
  breeder. 
  

   Conner 
  (1909) 
  gives 
  an 
  observation 
  of 
  breeding 
  in 
  November. 
  Surber 
  

   (1912) 
  figures 
  an 
  immature 
  glochidium, 
  giving 
  dimensions 
  which 
  

   correspond 
  closely 
  with 
  the 
  mature 
  embryo, 
  together 
  with 
  observa- 
  

   tions 
  on 
  the 
  breeding 
  season. 
  Simpson 
  (1900, 
  p. 
  776) 
  is 
  of 
  the 
  opinion, 
  

   since 
  he 
  has 
  seen 
  so 
  few 
  gravid 
  specimens, 
  that 
  the 
  breeding 
  ol 
  these 
  

   species 
  is 
  only 
  at 
  long 
  intervals. 
  It 
  is 
  apparent 
  from 
  the 
  above 
  

   references 
  that 
  the 
  observations 
  upon 
  the 
  breeding 
  of 
  this 
  species 
  

   have 
  been 
  quite 
  limited 
  and 
  I 
  know 
  of 
  no 
  description 
  of 
  mature 
  

   glochidia, 
  with 
  the 
  exception 
  of 
  Lea's 
  (1857, 
  p. 
  46). 
  In 
  his 
  descrip- 
  

   tion 
  there 
  is 
  no 
  reference 
  to 
  the 
  time 
  of 
  breeding 
  and 
  he 
  has 
  omitted 
  

   anatomical 
  features 
  that 
  are 
  distinctive. 
  He 
  says: 
  

  

  Unio 
  multiplicatits 
  (synonym 
  for 
  Q. 
  heros) 
  Lea, 
  fip;ure 
  3. 
  Pouch 
  shape; 
  dorsal 
  line 
  

   long; 
  side 
  margins 
  gently 
  ciirved, 
  basal 
  margin 
  slightly 
  rounded; 
  color 
  clear 
  white. 
  

   Has 
  no 
  hooks. 
  

  

  