﻿GLOCHIDIA 
  OF 
  FRESH-WATER 
  MUSSELS. 
  7 
  

  

  Semielliptical 
  in 
  shape; 
  ventral 
  margin 
  somewhat 
  acutely 
  rounded; 
  

   hinge 
  line 
  long, 
  straight; 
  size 
  extremely 
  small, 
  0.050 
  by 
  0.052 
  mm. 
  

  

  This 
  minute 
  glochidium 
  suggests 
  Tritogonia 
  tuberculata 
  m 
  general 
  

   shape 
  but 
  has 
  less 
  proportionate 
  depth, 
  with 
  longer 
  hinge 
  Hue. 
  

   Host 
  unknown. 
  

  

  Ohovaria 
  circulus 
  Lea. 
  [Fig. 
  8.1 
  

  

  Wabash 
  River, 
  Vincennes, 
  Ind., 
  June 
  9, 
  1913. 
  Collected 
  by 
  Ernest 
  

   Danglade; 
  collection 
  of 
  United 
  States 
  Biological 
  Laboratory, 
  no. 
  

   G-69. 
  

  

  Semielliptical 
  in 
  shape; 
  ventral 
  margin 
  rounded; 
  hinge 
  line 
  long 
  

   and 
  slightly 
  depressed 
  near 
  center; 
  size 
  medium, 
  0.170 
  by 
  0.215 
  mm. 
  

  

  This 
  glochidium 
  is 
  apparently 
  intermediate 
  in 
  form 
  between 
  retusa 
  

   and 
  ellipsis, 
  but 
  rather 
  nearer 
  the 
  latter, 
  yet 
  it 
  differs 
  from 
  both 
  in 
  

   being 
  of 
  smaUer 
  size. 
  In 
  ellipsis 
  the 
  hinge 
  line 
  is 
  straight, 
  while 
  in 
  

   retusa 
  the 
  same 
  line 
  is 
  undulated. 
  Host 
  unknown. 
  

  

  Quadrula 
  coccinea 
  Conrad. 
  [Fig. 
  9.1 
  

  

  St. 
  Joe 
  River, 
  Fort 
  Wayne, 
  Ind., 
  June, 
  1913. 
  Collected 
  by 
  

   H. 
  Walton 
  Clark; 
  collection 
  of 
  United 
  States 
  Biological 
  Laboratory, 
  

   no. 
  G-71. 
  

  

  Semicircular 
  in 
  shape; 
  ventral 
  margin 
  rounded, 
  somewhat 
  oblique; 
  

   hinge 
  line 
  long 
  and 
  straight; 
  size 
  medium, 
  0.160 
  by 
  0.160 
  mm. 
  

  

  This 
  glochidium 
  is 
  of 
  the 
  tyj^e 
  represented 
  by 
  ehena, 
  plicata, 
  etc., 
  

   and 
  very 
  closely 
  resembles 
  solida, 
  with 
  which 
  it 
  agrees 
  in 
  size 
  Init 
  

   differs 
  in 
  the 
  obliquely 
  rounded 
  ventral 
  margin. 
  As 
  a 
  parasite 
  it 
  

   would 
  be 
  difficult 
  to 
  distinguish 
  from 
  solida. 
  Host 
  unknown. 
  

  

  Quadrula 
  lieros 
  Say. 
  [Fig. 
  10.1 
  

  

  Mississippi 
  River, 
  Moline, 
  111., 
  September 
  24, 
  1912. 
  Collected 
  by 
  

   Arthur 
  D. 
  Howard; 
  collection 
  of 
  United 
  States 
  Biological 
  Laboratory, 
  

   no. 
  G-51. 
  

  

  Semielliptical 
  in 
  shape; 
  ventral 
  margin 
  obliquely 
  rounded; 
  hinge 
  

   line 
  long, 
  undulated, 
  oblique; 
  size 
  large, 
  0.260 
  by 
  0.340 
  mm. 
  

  

  Tills 
  glochidium 
  is 
  subject 
  to 
  more 
  variation 
  than 
  any 
  other 
  with 
  

   which 
  I 
  am 
  familiar. 
  For 
  instance, 
  some 
  specimens 
  from 
  Caddo 
  

   Lake, 
  Tex., 
  collected 
  by 
  Mr. 
  Austm 
  F. 
  Shira, 
  who 
  has 
  kindly 
  allowed 
  

   me 
  to 
  study 
  his 
  material, 
  are 
  uniformly 
  shorter 
  and 
  more 
  oval 
  in 
  

   outline, 
  with 
  hmge 
  Ime 
  less 
  obhque, 
  than 
  specimens 
  from 
  the 
  Ohio 
  

   and 
  Mississippi 
  Rivere, 
  and 
  the 
  variation 
  in 
  size 
  is 
  remarkable, 
  the 
  

   extremes 
  bemg 
  0.300 
  by 
  0.340 
  and 
  0.250 
  by 
  0.262 
  mm. 
  Another 
  

   example, 
  from 
  White 
  River, 
  Ark., 
  measures 
  0.280 
  by 
  0.380 
  mm. 
  

   Notwithstanding 
  its 
  great 
  variation 
  in 
  size, 
  and 
  even 
  outline, 
  this 
  

   species 
  can 
  not 
  readily 
  be 
  confused 
  with 
  any 
  other, 
  even 
  though 
  the 
  

   larval 
  gland 
  may 
  have 
  been 
  absorbed, 
  which 
  occurs 
  during 
  meta- 
  

   morphosis. 
  This 
  coiled 
  gland 
  is 
  a 
  promment 
  feature 
  in 
  the 
  mature 
  

  

  