﻿6 
  GLOCHIDIA 
  OF 
  FEESH-WATER 
  MTUSSELS. 
  

  

  If 
  we 
  except 
  the 
  shape 
  and 
  size 
  of 
  the 
  adductor 
  this 
  glochidium 
  is 
  

   ahnost 
  identical 
  with 
  that 
  of 
  L. 
  iris, 
  both 
  in 
  outhne 
  and 
  size. 
  The 
  

   specimen 
  of 
  iris 
  used 
  for 
  comparison 
  with 
  this, 
  and 
  from 
  which 
  my 
  

   figure 
  of 
  that 
  species 
  was 
  drawn," 
  came 
  from 
  the 
  Yellow 
  River, 
  Ind. 
  

   If 
  the 
  character 
  of 
  the 
  glochidium 
  is 
  a 
  factor 
  in 
  the 
  classification 
  of 
  

   the 
  Unionidse, 
  and 
  I 
  believe 
  it 
  is, 
  then 
  the 
  separation 
  of 
  'picta 
  and 
  

   iris, 
  even 
  subspecifically, 
  is 
  difficult. 
  Adult 
  shells 
  of 
  2>icta 
  from 
  the 
  

   Cumberland 
  River 
  and 
  iris 
  from 
  Yellow 
  River 
  seem 
  to 
  differ, 
  but 
  it 
  

   might 
  be 
  interesting 
  to 
  compare 
  them 
  with 
  a 
  series 
  from 
  an 
  inter- 
  

   mediate 
  locality, 
  like 
  the 
  Ohio 
  River, 
  for 
  mstance. 
  Host 
  unknown. 
  

  

  Lampsilis 
  yurpurata 
  Lamarck. 
  [Fig. 
  5, 
  5a.] 
  

  

  Cache 
  River, 
  near 
  Clarendon, 
  Ark., 
  January 
  15, 
  1913. 
  Collected 
  

   by 
  Tliaddeus 
  Surbcr; 
  collection 
  of 
  United 
  States 
  Biological 
  Labora- 
  

   tory, 
  no. 
  G-60. 
  

  

  Proftera 
  type; 
  axe-head 
  shape; 
  with 
  two 
  spines, 
  one 
  at 
  each 
  of 
  the 
  

   ventral 
  corners 
  of 
  the 
  shell; 
  size 
  large, 
  0.200 
  by 
  0.360 
  mm. 
  

  

  Though 
  slightly 
  smaller 
  than 
  alata, 
  this 
  species 
  is 
  almost 
  identical 
  

   in 
  shape, 
  except 
  that 
  it 
  has 
  a 
  decidedly 
  more 
  curved 
  ventral 
  margin 
  

   and 
  better 
  developed 
  hooks. 
  All 
  the 
  members 
  of 
  the 
  axe-head 
  group, 
  

   so 
  far 
  as 
  known, 
  undergo 
  wonderful 
  changes 
  while 
  passing 
  through 
  

   their 
  metamorphosis 
  and 
  this 
  species 
  is 
  no 
  exception, 
  the 
  growth 
  of 
  

   the 
  infant 
  mussel, 
  while 
  parasitic, 
  being 
  as 
  great 
  as 
  Imvissima. 
  

  

  Host 
  : 
  Tlie 
  specific 
  host 
  of 
  this 
  mtissel 
  is 
  apparently 
  the 
  sheepshead 
  

   (Aplodinotus 
  grunniens), 
  on 
  which 
  it 
  occurs 
  as 
  a 
  gill 
  parasite. 
  During 
  

   January 
  (12th 
  to 
  16th), 
  1913, 
  the 
  ^vriter 
  secured 
  five 
  infected 
  fish 
  in 
  

   the 
  Cache 
  River, 
  Ai'k., 
  the 
  number 
  borne 
  by 
  each 
  fish 
  being, 
  approx- 
  

   imately, 
  as 
  follows: 
  512, 
  172, 
  68, 
  192, 
  and 
  500, 
  in 
  various 
  stages 
  of 
  

   development. 
  One 
  fish 
  bore 
  a 
  single 
  glochidium 
  on 
  the 
  ventral 
  fin, 
  

   probably 
  more 
  or 
  less 
  accidental. 
  

  

  Lam/psilis 
  ventricosa 
  satura 
  Lea. 
  [Fig. 
  6.] 
  

  

  Wliite 
  River, 
  Newport, 
  Ark., 
  November 
  16, 
  1912. 
  Collected 
  by 
  

   W. 
  H. 
  Thomas; 
  collection 
  of 
  United 
  States 
  Biological 
  Laboratory, 
  

   no. 
  G-55. 
  

  

  Glochidium 
  semielliptical 
  in 
  shape; 
  ventral 
  margin 
  rounded; 
  hinge 
  

   Ime 
  rather 
  oblique; 
  size 
  medium, 
  0.205 
  by 
  0.245 
  mm. 
  

  

  Closely 
  resembles 
  ventricosa 
  typicus, 
  from 
  which 
  it 
  differs 
  only 
  in 
  

   the 
  oblique 
  hinge 
  line 
  and 
  in 
  having 
  proportionately 
  less 
  depth, 
  the 
  

   depth 
  of 
  shell 
  being 
  about 
  one 
  one-hundredth 
  of 
  a 
  millimeter 
  less 
  than 
  

   in 
  ventricosa. 
  Host 
  unknown, 
  

  

  Margaritana 
  monodonta 
  Say. 
  [Fig. 
  7.] 
  

  

  Mississippi 
  River, 
  near 
  Molme, 
  111., 
  May 
  2, 
  1913. 
  Collected 
  by 
  

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

   no. 
  G-68. 
  

  

  a 
  Surbcr, 
  op. 
  eit., 
  fig. 
  46, 
  pi. 
  III. 
  

  

  