﻿EXPLANATION 
  OF 
  FIGURES. 
  

  

  Photograplis 
  and 
  drawings 
  by 
  the 
  author, 
  the 
  drawings 
  beiag 
  

   made 
  with 
  the 
  aid 
  of 
  a 
  camera 
  kicida. 
  

  

  Plate 
  I. 
  

  

  Fig. 
  1. 
  Quadrula 
  pustulosa 
  (Lea). 
  Interior 
  of 
  right 
  valve. 
  

  

  Fig. 
  2. 
  Same 
  individual. 
  Exterior 
  of 
  left 
  valve. 
  

  

  Fig. 
  3. 
  Juvenile 
  of 
  same 
  species. 
  

  

  Fig. 
  4. 
  Quadrula 
  metanevra 
  Rafinesque. 
  Interior 
  of 
  right 
  valve. 
  

  

  Fig. 
  5. 
  Same 
  individual. 
  Exterior 
  of 
  left 
  valve. 
  

  

  Fig. 
  6. 
  Juvenile 
  of 
  same 
  species. 
  

  

  Fig. 
  7. 
  Quadrula 
  ebena 
  (Lea). 
  Interior 
  of 
  right 
  valve. 
  

  

  Fig. 
  8. 
  Same 
  individual. 
  Exterior 
  of 
  left 
  valve. 
  

  

  Fig. 
  9. 
  Juvenile 
  of 
  same 
  species. 
  

  

  Fig. 
  10. 
  Quadrula 
  trigona 
  (Lea). 
  Interior 
  of 
  right 
  valve. 
  

  

  Fig. 
  11. 
  Same 
  individual. 
  Exterior 
  of 
  left 
  valve. 
  

  

  Fig. 
  12. 
  Juvenile 
  of 
  same 
  species. 
  

  

  Plate 
  II. 
  

  

  Fig. 
  13. 
  Juvenile 
  of 
  Quadrula 
  heros 
  (Say). 
  

  

  Fig. 
  14. 
  Adult 
  of 
  same 
  species. 
  Left 
  valve. 
  

  

  Fig. 
  15. 
  The 
  same 
  species. 
  Interior 
  of 
  right 
  valve. 
  

  

  Fig. 
  16. 
  Juvenile 
  of 
  Quadrula 
  plicata 
  (Say). 
  

  

  Fig. 
  17. 
  Adult 
  of 
  same 
  species. 
  Exterior 
  of 
  left 
  valve. 
  

  

  Fig. 
  18. 
  The 
  same 
  species. 
  Interior 
  of 
  right 
  valve. 
  

  

  Plate 
  III. 
  

  

  Fig. 
  19. 
  Glochidium 
  of 
  Quadrula 
  pustulosa 
  implanted 
  upon 
  the 
  gill 
  of 
  Ictalurus 
  

   punctatus; 
  a 
  natural 
  infection 
  taken 
  August 
  26. 
  Considerable 
  development 
  is 
  evident 
  

   from 
  the 
  growth 
  of 
  shell 
  at 
  the 
  edge 
  of 
  the 
  glochidial 
  valves 
  (e. 
  g. 
  s.) 
  and 
  two 
  adductor 
  

   muscles 
  {Ad. 
  m.) 
  and 
  foot 
  (/o.) 
  that 
  are 
  visible. 
  The 
  blood 
  vessels 
  {B. 
  V.) 
  of 
  the 
  

   fish's 
  gills 
  are 
  seen 
  to 
  be 
  inclosed 
  by 
  the 
  valves 
  of 
  the 
  glochidium. 
  This 
  is 
  the 
  same 
  

   glochidium 
  as 
  that 
  shown 
  in 
  figure 
  23. 
  

  

  Fig. 
  20. 
  An 
  abnormal 
  cyst 
  produced 
  by 
  the 
  glochidium 
  of 
  Quadrula 
  pustulosa 
  upon 
  

   the 
  gill 
  of 
  Ictalurus 
  punctatus. 
  

  

  Fig. 
  21. 
  Glochidium 
  of 
  Quadrula 
  heros 
  showing 
  the 
  larval 
  thread 
  (I. 
  t.) 
  and 
  larval 
  

   thread 
  gland 
  (It. 
  g.) 
  clearly 
  differentiated 
  by 
  staining 
  in 
  borax 
  carmine. 
  The 
  adductor 
  

   muscle 
  {Ad. 
  m.) 
  lies 
  in 
  the 
  center. 
  

  

  Fig. 
  22. 
  Glochidium 
  of 
  Quadrula 
  heros 
  with 
  gaping 
  valves 
  seen 
  from 
  a 
  side 
  view. 
  

   The 
  larval 
  thread 
  {I. 
  <.).is 
  to 
  be 
  seen 
  between 
  the 
  valves 
  and 
  its 
  point 
  of 
  emergence 
  

   ventral 
  to 
  the 
  adductor 
  muscle. 
  Inner 
  and 
  outer 
  sensory 
  hair 
  cells 
  (s. 
  h. 
  c.) 
  are 
  

   visible 
  on 
  each 
  valve. 
  

  

  Fig. 
  23. 
  Filament 
  of 
  gill 
  of 
  Ictalurus 
  punctatus 
  naturally 
  infected 
  by 
  the 
  glochidium 
  

   of 
  Quadrula 
  pustulosa. 
  The 
  cyst 
  is 
  set 
  off 
  on 
  each 
  side 
  by 
  incisions 
  of 
  the 
  filament. 
  

   This 
  is 
  somewhat 
  characteristic 
  of 
  gill 
  cysts 
  in 
  this 
  species 
  though 
  not 
  constant. 
  The 
  

   same 
  glochidium 
  is 
  shown 
  in 
  figure 
  19. 
  

  

  Fig. 
  24. 
  Encysted 
  glochidium 
  of 
  Quadrula 
  ebena, 
  artificial 
  infection 
  upon 
  Microp- 
  

   terus 
  salmoides. 
  The 
  large 
  size 
  of 
  the 
  cyst 
  is 
  to 
  be 
  noted 
  as 
  characteristic 
  of 
  infections 
  

   with 
  this 
  species 
  of 
  glochidium. 
  

  

  51 
  

  

  