﻿8 
  GLOCHIDIA 
  OF 
  FRESH-WATER 
  MUSSELS. 
  

  

  glochidium, 
  as 
  will 
  be 
  noted 
  by 
  reference 
  to 
  the 
  figure 
  (fig, 
  10), 
  where 
  

   it 
  is 
  shown 
  without 
  undue 
  amphfication. 
  

  

  Host: 
  In 
  Arkansas, 
  last 
  January 
  (1913), 
  I 
  found 
  this 
  species 
  

   parasitic 
  in 
  considerable 
  numbers 
  on 
  the 
  fins 
  of 
  the 
  sheepshead 
  

   (Aplodinotus 
  grunniens) 
  but 
  none 
  were 
  present 
  on 
  the 
  gills 
  of 
  the 
  

   same 
  fish. 
  Thus 
  we 
  are 
  forced 
  to 
  conclude 
  it 
  is 
  a 
  fin 
  parasite, 
  not- 
  

   withstanding 
  the 
  fact 
  that 
  a 
  specimen 
  of 
  eel 
  (A. 
  chrysipa) 
  taken 
  at 
  

   the 
  same 
  place 
  — 
  Cache 
  River, 
  near 
  Clarendon, 
  Ark.— 
  held 
  a 
  single 
  

   glochidium 
  on 
  its 
  gills, 
  and 
  a 
  "water 
  dog" 
  (Necturus 
  maculosus) 
  also 
  

   held 
  one 
  on 
  the 
  gills. 
  The 
  structure 
  of 
  the 
  gills 
  of 
  the 
  Necturus 
  

   maculosus 
  resembles 
  the 
  fin 
  structure 
  of 
  fishes 
  and 
  may 
  function 
  the 
  

   same, 
  so 
  it 
  may 
  not 
  be 
  at 
  all 
  remarkable 
  to 
  find 
  mussel 
  larv?e 
  infecting 
  

   them, 
  at 
  least 
  of 
  those 
  species 
  which 
  take 
  externally 
  on 
  fishes. 
  

  

  Quadrula 
  lacJirymosa 
  hea,. 
  [Fig. 
  11.] 
  

  

  Tributary 
  of 
  Fall 
  River, 
  Greenwood 
  County, 
  Kans., 
  August, 
  1912. 
  

   Collected 
  by 
  Kansas 
  Biological 
  Survey; 
  collection 
  of 
  United 
  States 
  

   Biological 
  Laboratory, 
  no. 
  G-63. 
  

  

  Glochidium 
  (not 
  fully 
  matured) 
  semielliptical 
  in 
  shape; 
  ventral 
  

   margin 
  rounded; 
  hmge 
  line 
  rather 
  short, 
  usually 
  depressed, 
  but 
  

   sometimes 
  straight; 
  size 
  small, 
  0.085 
  by 
  0.090 
  mm. 
  

  

  The 
  shape 
  of 
  this 
  glochidium 
  is 
  suggestive 
  of 
  Tritogonia 
  tuherculata, 
  

   but 
  has 
  a 
  shorter 
  hinge 
  Ime 
  and 
  less 
  depth; 
  the 
  size 
  is 
  practically 
  

   the 
  same, 
  and 
  with 
  our 
  present 
  knowledge 
  it 
  might 
  be 
  possible 
  to 
  

   confuse 
  the 
  two 
  species, 
  especially 
  when 
  examined 
  as 
  parasites. 
  Host 
  

   unknown. 
  

  

  Quadrula 
  ohliqua 
  Lamarck. 
  [Fig. 
  12.] 
  

  

  Cumberland 
  River, 
  Burnside, 
  Ky., 
  July 
  14, 
  1911. 
  Collected 
  by 
  

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

   no. 
  G-66. 
  

  

  Glochidium 
  of 
  the 
  trigona 
  type; 
  semicircular; 
  hinge 
  line 
  long 
  and 
  

   straight; 
  depth 
  greater 
  than 
  length; 
  size 
  medium, 
  0.160 
  by 
  0.175 
  

   mm. 
  

  

  This 
  glochidium 
  seems 
  to 
  be 
  rather 
  intermediate 
  in 
  shape 
  between 
  

   Q. 
  trigona 
  and 
  TJnio 
  gibhosa, 
  agreemg 
  with 
  the 
  former 
  in 
  length, 
  but 
  

   with 
  less 
  depth, 
  trigona 
  being 
  longer 
  than 
  deep, 
  and 
  ohliqua 
  deeper 
  

   than 
  long. 
  While 
  agreemg 
  with 
  gibhosa 
  in 
  shape, 
  except 
  somewhat 
  

   longer 
  hinge 
  line, 
  it 
  is 
  much 
  smaller 
  and 
  is 
  not 
  likely 
  to 
  be 
  confused 
  

   with 
  it. 
  Host 
  unknown. 
  

  

  TJnio 
  crassidens 
  Lamarck. 
  [Fig. 
  13.] 
  

  

  Cumberland 
  River, 
  Burnside, 
  Ky., 
  July 
  14, 
  1911. 
  Collected 
  by 
  

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

   no. 
  Gr-65. 
  

  

  