﻿TBEMATODE 
  PARASITES 
  OF 
  FfSHFS—LiyTOX. 
  541 
  

  

  32. 
  MONOSTOMUM 
  ORBICULARE 
  Rudolphi. 
  

   (Plate 
  LIV, 
  ligs. 
  2-5.) 
  

  

  Monostonmm 
  orbiculare 
  Diesino, 
  Syst. 
  Helm., 
  I, 
  p. 
  320. 
  — 
  Pai!ONa, 
  Intoruo 
  al 
  

   Monojstomum. 
  Torino, 
  IXS". 
  

  

  No. 
  4872, 
  U.S.ISr.M, 
  The 
  description 
  of 
  this 
  species 
  giveu 
  by 
  Dies- 
  

   ing 
  is 
  very 
  brief, 
  and, 
  like 
  Uujardiu's' 
  description, 
  is 
  taken 
  directly 
  

   from 
  Ilndolpbi's 
  brief 
  account. 
  I 
  have 
  not 
  seen 
  Paroua's 
  paper. 
  The 
  

   worm 
  is 
  described 
  by 
  the 
  older 
  helminthologists 
  as 
  being- 
  from 
  2 
  to 
  3 
  

   mm. 
  in 
  length, 
  orbicular, 
  convex 
  above, 
  concave 
  or 
  rarely 
  plane 
  below; 
  

   oral 
  aperture 
  terminal 
  oval 
  oblong 
  sometimes 
  slightly 
  projecting. 
  

  

  Specimens 
  of 
  Monofitoma, 
  14 
  in 
  number, 
  from 
  the 
  intestine 
  of 
  Lobotcs 
  

   si(ri)t<(i)u'7i.sis 
  (Woods 
  Holl, 
  Massachusetts, 
  August 
  G, 
  1887), 
  agree 
  with 
  

   the 
  above 
  synopsis 
  of 
  specific 
  characters. 
  

  

  ^Measurements 
  of 
  a 
  typical 
  specimen, 
  in 
  life, 
  yielded 
  the 
  following 
  

   results: 
  Length, 
  U.7 
  mm.; 
  diameter 
  of 
  sucker, 
  0.20; 
  breadth 
  of 
  body 
  

   at 
  sucker, 
  0.52; 
  maximum 
  breadth, 
  1; 
  breadth 
  near 
  posterior 
  end, 
  0.20; 
  

   distance 
  of 
  sucker 
  from 
  anterior 
  end 
  of 
  body, 
  0.04; 
  diameter 
  of 
  repro- 
  

   ductive 
  aperture 
  at 
  posterior 
  end, 
  CI. 
  Two 
  other 
  specimens 
  were 
  

   measured 
  with 
  very 
  nearly 
  corresponding 
  results, 
  the 
  diameter 
  of 
  the 
  

   sucker 
  being 
  exactly 
  the 
  same 
  in 
  each 
  case. 
  The 
  measurements 
  were 
  

   made 
  on 
  specimens 
  which 
  were 
  lying 
  freely 
  in 
  water. 
  The 
  si)ecimeus 
  

   present 
  but 
  little 
  variety 
  of 
  form. 
  They 
  are 
  ovate, 
  broadest 
  about 
  

   the 
  anterior 
  third, 
  tapering 
  very 
  little 
  toward 
  the 
  anterior 
  end, 
  which 
  

   is 
  broadly 
  rounded 
  and 
  usually 
  marked 
  with 
  very 
  tine 
  transverse 
  lines, 
  

   making 
  a 
  finely 
  serrate 
  outline 
  when 
  flattened 
  under 
  the 
  compressor. 
  

   They 
  taper 
  gradually 
  toward 
  the 
  posterior 
  end, 
  which 
  is 
  bluntly 
  rounded 
  

   and 
  carries 
  the 
  aperture 
  of 
  the 
  generative 
  organs 
  at 
  its 
  tip. 
  The 
  oral 
  

   sucker 
  is 
  on 
  the 
  ventral 
  side 
  very 
  near 
  the 
  anterior 
  margin, 
  its 
  diameter 
  

   equal 
  to 
  about 
  one 
  tenth 
  the 
  length 
  of 
  the 
  body. 
  

  

  The 
  uterus 
  is 
  voluminous 
  and 
  filled 
  with 
  small 
  ova 
  which 
  are 
  nearly 
  

   globular. 
  The 
  folds 
  of 
  the 
  uterus 
  lie 
  for 
  the 
  most 
  part 
  along 
  the 
  left 
  

   side 
  of 
  the 
  body, 
  but 
  there 
  is 
  a 
  large 
  mass 
  of 
  ova 
  near 
  the 
  posterior 
  

   end 
  which 
  lies 
  mainly 
  on 
  the 
  left 
  side 
  of 
  the 
  middle 
  line. 
  The 
  testes 
  

   are 
  two, 
  oval, 
  and 
  lie 
  about 
  the 
  middle 
  of 
  the 
  body 
  on 
  the 
  right 
  side. 
  

   The 
  ovary 
  is 
  a 
  globular 
  organ, 
  also 
  lying 
  on 
  the 
  right 
  side 
  at 
  about 
  the 
  

   anterior 
  third. 
  The 
  vitellaria 
  lie 
  along 
  both 
  right 
  and 
  left 
  sides 
  of 
  the 
  

   anterior 
  third 
  and 
  across 
  the 
  anterior 
  end 
  behind 
  the 
  sucker. 
  In 
  life 
  

   they 
  ai)pear 
  to 
  be 
  branched 
  organs 
  of 
  a 
  light 
  purple 
  color. 
  The 
  long, 
  

   oval, 
  muscular 
  cirrus 
  pouch 
  lies 
  near 
  the 
  median 
  line, 
  about 
  the 
  poste- 
  

   rior 
  third 
  of 
  the 
  body, 
  its 
  aperture 
  directed 
  posteriorly 
  and 
  a 
  little 
  to 
  

   the 
  left. 
  The 
  muscular 
  pharynx 
  lies 
  a 
  little 
  to 
  the 
  right 
  of 
  the 
  median 
  

   line 
  and 
  a 
  little 
  in 
  front 
  of 
  the 
  middle 
  of 
  the 
  body. 
  It 
  presents 
  the 
  

   appearance 
  of 
  a 
  strong 
  globular 
  bulb 
  connected 
  with 
  a 
  tubular 
  anterior 
  

   prolongation 
  less 
  nmscular, 
  apparently 
  a 
  part 
  of 
  the 
  oisophagus. 
  The 
  

  

  iHist. 
  Hehii., 
  p. 
  360. 
  

  

  