﻿62 
  PROPAGATION 
  OF 
  FEESH-WATER 
  MUSSELS. 
  

  

  Plate 
  IV. 
  

  

  Fig. 
  25. 
  A 
  dorsal 
  view 
  of 
  a 
  juvenile 
  of 
  Lampsilis 
  alata, 
  9 
  mm. 
  long, 
  showing 
  the 
  

   glochidial 
  shell 
  still 
  visible. 
  Magnification, 
  18 
  diameters. 
  

  

  Fig. 
  26a. 
  A 
  cluster 
  of 
  glochidia 
  of 
  Quadrula 
  hews 
  (Say), 
  imbedded 
  in 
  the 
  pectoral 
  

   fin 
  of 
  a 
  sheepshead, 
  Aplodinotus 
  grunniens. 
  The 
  fish 
  was 
  infected 
  artificially 
  October 
  

   7; 
  these 
  glochidia 
  were 
  removed 
  by 
  clipping 
  off 
  a 
  small 
  portion 
  of 
  the 
  fin 
  April 
  18. 
  

   The 
  soft 
  parts 
  are 
  sufficiently 
  distinct 
  to 
  permit 
  the 
  determination 
  of 
  the 
  amount 
  of 
  

   metamorphosis 
  which 
  is 
  nearly 
  completed. 
  Differences 
  in 
  appearance 
  of 
  the 
  indi- 
  

   viduals 
  are 
  due 
  chie 
  ly 
  to 
  their 
  varied 
  orientation. 
  The 
  narrowest 
  figure 
  is 
  an 
  optical 
  

   section 
  taken 
  in 
  a 
  transverse 
  plane 
  at 
  right 
  angles 
  to 
  the 
  longitudinal 
  axis. 
  The 
  

   preparation 
  was 
  stained 
  by 
  Mayer's 
  hsemalum. 
  

  

  Fig. 
  26b. 
  Gill 
  filament 
  of 
  a 
  sunfish, 
  Lepomis 
  pallidus, 
  artificially 
  infected 
  by 
  the 
  

   glochidium 
  of 
  Quadrula 
  heros. 
  Age 
  (Dec. 
  6), 
  69 
  days. 
  The 
  presence 
  of 
  two 
  adductor 
  

   muscles 
  indicates 
  that 
  some 
  metamorphosis 
  has 
  taken 
  place. 
  The 
  cyst 
  is 
  seen 
  to 
  be 
  

   thin 
  as 
  compared 
  with 
  some 
  other 
  species. 
  Drawn 
  in 
  a 
  living 
  condition 
  immediately 
  

   after 
  removal 
  of 
  the 
  filament 
  from 
  the 
  gill 
  of 
  the 
  fish. 
  

  

  Fig. 
  27. 
  Natural 
  infection 
  of 
  the 
  herring, 
  Pomolobus 
  chrysochloris, 
  by 
  the 
  glochidia 
  

   of 
  Unio 
  crassidens. 
  This 
  fish 
  was 
  captured 
  May 
  16. 
  The 
  figure 
  represents 
  the 
  tip 
  

   of 
  a 
  filament 
  shown 
  chiefly 
  in 
  outline 
  by 
  dotted 
  lines. 
  The 
  cyst 
  includes 
  a 
  number 
  

   of 
  the 
  finer 
  subdivisions 
  of 
  the 
  filament 
  each 
  with 
  its 
  afferrent 
  blood 
  vessel. 
  

  

  Fig. 
  28. 
  A 
  natural 
  infection 
  of 
  the 
  sheepshead, 
  Aplodinotus 
  grunniens, 
  by 
  Lampsilis 
  

   alata. 
  Considerable 
  growth 
  of 
  shell 
  is 
  to 
  be 
  seen 
  beyond 
  the 
  valves 
  of 
  the 
  glochidium 
  

   while 
  still 
  imbedded 
  in 
  the 
  tissue 
  of 
  the 
  host. 
  

  

  Plate 
  V. 
  

  

  Glochidia 
  of 
  species 
  of 
  Quadrula. 
  All 
  figures 
  are 
  magnified 
  275 
  diameters. 
  

  

  Fig. 
  29. 
  Quadrula 
  lachrymosa 
  (Lea). 
  A 
  little 
  immature; 
  left 
  valve, 
  showing 
  large 
  

   mantle 
  cells 
  just 
  beneath 
  the 
  very 
  transparent 
  shell 
  and 
  large 
  adductor 
  muscle. 
  

  

  Fig. 
  30. 
  Quadrula 
  ebena 
  (Lea). 
  Surface 
  view 
  of 
  right 
  valve, 
  showing 
  adductor 
  

   muscle 
  and 
  pores 
  of 
  shell. 
  

  

  Fig. 
  31. 
  Quadrula 
  metanevra 
  Rafinesque. 
  Surface 
  view 
  of 
  left 
  valve. 
  

  

  Fig. 
  32. 
  Quadrula 
  plicata 
  (Say). 
  Right 
  valve, 
  showing 
  thread 
  gland 
  passing 
  around 
  

   the 
  adductor 
  muscle 
  and 
  thread 
  issuing 
  posterior 
  to 
  the 
  muscle. 
  

  

  Fig. 
  33. 
  Quadrula 
  trigona 
  (Lea). 
  A 
  surface 
  view 
  of 
  the 
  right 
  valve. 
  

  

  Fig. 
  34. 
  Qundrula 
  solida 
  (Lea). 
  A 
  surface 
  view 
  of 
  the 
  left 
  valve. 
  

  

  Fig. 
  35. 
  Quadrula 
  heros 
  (Say). 
  The 
  left 
  valve 
  with 
  the 
  focus 
  of 
  the 
  microscope 
  

   slightly 
  below 
  the 
  surface. 
  The 
  large 
  light 
  circle 
  is 
  the 
  expanded 
  portion 
  of 
  the 
  

   thread 
  gland. 
  The 
  shaded 
  area 
  represents 
  an 
  organ 
  whose 
  function 
  has 
  not 
  been 
  

   determined. 
  A 
  similar 
  structure 
  is 
  visible 
  in 
  figs. 
  30 
  and 
  32; 
  in 
  the 
  latter 
  it 
  appears 
  

   to 
  be 
  continuous 
  with 
  the 
  thread 
  gland. 
  

  

  Fig. 
  36. 
  Quadrula 
  pustulosa 
  (Lea). 
  Left 
  valve; 
  surface 
  view. 
  

  

  Plate 
  VI. 
  

  

  Fig. 
  37. 
  Quadrula 
  pustulata 
  (Lea). 
  Interior 
  of 
  the 
  right 
  valve. 
  

   Fig. 
  38. 
  The 
  same 
  species. 
  Left 
  valve. 
  

   Fig. 
  39. 
  Juvenile 
  of 
  the 
  same 
  species. 
  

  

  Fig. 
  40. 
  Quadrula 
  granifera 
  (Lea). 
  Interior 
  of 
  the 
  right 
  valve. 
  The 
  dark 
  shade 
  is 
  

   due 
  to 
  the 
  purple 
  nacre 
  of 
  this 
  shell. 
  

   Fig. 
  41. 
  The 
  same 
  species. 
  Left 
  valve. 
  

   Fig. 
  42. 
  Juvenile 
  of 
  the 
  same 
  species. 
  

  

  Fig. 
  43. 
  Quadrula 
  lachrymosa 
  (Lea). 
  Interior 
  of 
  the 
  right 
  valve. 
  

   Fig. 
  44. 
  The 
  same 
  species. 
  Left 
  valve. 
  > 
  

  

  Fig. 
  45. 
  Juvenile 
  of 
  the 
  same 
  species. 
  

   Fig. 
  46. 
  Quadrula 
  solida 
  (Lea). 
  Interior 
  of 
  the 
  right 
  valve. 
  

   Fig. 
  47. 
  The 
  same 
  species. 
  Left 
  valve. 
  

  

  