﻿N0.li:?3. 
  TREMATODE 
  P-AUASITES 
  OE 
  FISHES— 
  LI. 
  XTOX. 
  533 
  

  

  demonstrated; 
  what 
  appeared 
  to 
  be 
  <v 
  left 
  branch 
  of 
  the 
  ()t'Soi)lia,uus 
  

   was 
  traced 
  for 
  some 
  distance, 
  about 
  lialf 
  tlie 
  length 
  of 
  the 
  neck. 
  In 
  

   tills 
  minute 
  vessel 
  Avhich 
  leads 
  back 
  from 
  the 
  pharynx 
  several 
  nucle- 
  

   ated 
  cells, 
  oval 
  in 
  shape, 
  and 
  about 
  0.01 
  mm. 
  in 
  length, 
  were 
  observed, 
  

   which 
  I 
  take 
  to 
  be 
  the 
  red 
  blood-corpuscles 
  of 
  the 
  host. 
  What 
  are 
  

   taken 
  to 
  be 
  branches 
  of 
  the 
  intestine 
  in 
  this 
  species, 
  and 
  in 
  the 
  related 
  

   species 
  I), 
  nigroliarum 
  and 
  7>. 
  macrocotyle, 
  begin 
  as 
  two 
  small 
  lateral 
  

   vessels 
  on 
  either 
  side 
  of 
  tlie 
  neck 
  on 
  a 
  level 
  with 
  the 
  pharynx 
  but 
  not 
  

   coinnuinicating- 
  with 
  it 
  (Plate 
  LI, 
  fig. 
  3, 
  i. 
  i.): 
  at 
  least 
  I 
  was 
  unable 
  to 
  

   demonstrate 
  any 
  communication 
  in 
  my 
  sections. 
  They 
  are 
  irregular 
  in 
  

   dimensions, 
  becoming 
  much 
  enlarged 
  in 
  sotne 
  portions 
  of 
  the 
  body, 
  so 
  

   that 
  the 
  transverse 
  sections 
  of 
  the 
  two 
  vessels 
  constitute 
  more 
  than 
  

   half 
  the 
  area 
  of 
  the 
  entire 
  section 
  of 
  the 
  body. 
  At 
  such 
  places 
  they 
  

   are 
  filled 
  with 
  a 
  finely 
  granular 
  substance, 
  light 
  brown 
  in 
  color, 
  in 
  car- 
  

   mine-stained 
  sections. 
  A 
  few 
  of 
  the 
  tetragonal 
  crystals 
  observed 
  in 
  

   the 
  corresponding 
  vessels 
  of 
  />. 
  vif/roffavum 
  and 
  T>. 
  macrocotyle 
  were 
  

   seen 
  in 
  these. 
  

  

  In 
  addition 
  to 
  the 
  very 
  voluminous 
  tubular 
  seminal 
  receptacle 
  which 
  

   extends 
  from 
  the 
  pedicel 
  of 
  the 
  ventral 
  sucker 
  to 
  near 
  the 
  anterior 
  end 
  

   of 
  the 
  neck, 
  a 
  i)osterior 
  seminal 
  receptacle 
  was 
  observed 
  between 
  the 
  

   shell-gland 
  and 
  the 
  jiosterior 
  testis. 
  The 
  vas 
  deferens 
  and 
  uterus 
  have 
  

   the 
  same 
  general 
  plan 
  as 
  in 
  the 
  two 
  related 
  species, 
  but 
  the 
  prostatic 
  

   gland 
  traversed 
  by 
  the 
  former 
  is 
  not 
  so 
  large 
  as 
  in 
  />. 
  macrocott/le. 
  

  

  The 
  ovary 
  in 
  one 
  specimen 
  measured 
  0.43 
  mm. 
  in 
  diameter 
  and 
  was 
  

   situated 
  0.28 
  mm. 
  back 
  of 
  the 
  i)osterior 
  testis. 
  The 
  shell-gland 
  was 
  

   situated 
  adjacent 
  to 
  the 
  anterior 
  edge 
  of 
  the 
  ovary, 
  toward 
  the 
  right 
  

   side, 
  and 
  was 
  0.23 
  mm. 
  in 
  diameter. 
  In 
  another 
  the 
  ovary 
  was 
  0.53 
  

   and 
  the 
  shell-gland 
  0.21 
  mm. 
  in 
  diameter. 
  The 
  ovary 
  consisted 
  of 
  

   l)olygonal 
  nucleated 
  cells, 
  as 
  in 
  />. 
  nifirojiarion 
  and 
  D. 
  macrocotyle. 
  

  

  The 
  testes 
  in 
  two 
  specimens 
  which 
  were 
  cut 
  into 
  series 
  of 
  longitudinal 
  

   sections 
  jiresented 
  the 
  following 
  indivnlual 
  differences: 
  In 
  one 
  si)eii- 
  

   men 
  the 
  length 
  of 
  the 
  anterior 
  testis 
  was 
  1.02 
  mm., 
  that 
  of 
  the 
  poste 
  

   rior 
  testis 
  0.74, 
  the 
  former 
  situated 
  toward 
  the 
  right 
  and 
  the 
  latter 
  

   toward 
  the 
  left 
  side 
  of 
  the 
  body. 
  In 
  the 
  other 
  specimen 
  these 
  condi 
  

   tions 
  were 
  leversed, 
  i. 
  e., 
  the 
  length 
  of 
  the 
  anterior 
  testes 
  was 
  0.08, 
  

   that 
  of 
  the 
  posterior 
  testes 
  0.80, 
  while 
  the 
  former 
  wjis 
  situated 
  toward 
  

   the 
  left 
  and 
  the 
  latter 
  toward 
  the 
  right 
  side 
  of 
  the 
  body. 
  One 
  must 
  

   conclude 
  from 
  these 
  facts 
  that 
  relative 
  position 
  of 
  internal 
  organs 
  in 
  

   these 
  forms, 
  within 
  certain 
  not 
  too 
  narrow 
  limits, 
  does 
  not 
  supply 
  safe 
  

   criteria 
  for 
  establishing 
  specific 
  differences, 
  

  

  Olsson 
  represents, 
  in 
  a 
  longitudinal 
  section 
  of 
  the 
  neck 
  of 
  />. 
  uiyro- 
  

   ^fariim, 
  what 
  he 
  regards 
  as 
  glands 
  of 
  doubtful 
  significance 
  (Plate 
  LI, 
  

   fig. 
  2,) 
  This 
  structure 
  is 
  identical 
  in 
  position 
  with 
  the 
  nuchal 
  crest 
  of 
  

   B. 
  foil 
  at 
  urn. 
  

  

  Thirty 
  specimens 
  of 
  this 
  remarkable 
  worm 
  were 
  found 
  in 
  a 
  lot 
  of 
  dis- 
  

   toma 
  from 
  the 
  intestine 
  of 
  the 
  sunfish 
  {Mola 
  mola), 
  taken 
  off 
  Marthas 
  

   Vineyard, 
  September 
  10, 
  1880. 
  Vinal 
  N. 
  Edwards, 
  collector. 
  

  

  