﻿NO. 
  1125. 
  CESTODE 
  PJRJSITES 
  OE 
  FISHES— 
  LTXTOX. 
  437 
  

  

  16. 
  DIBOTHRIUM 
  OCCIDENTALE, 
  new 
  species. 
  

   (Plate 
  XXXII, 
  figs. 
  1-11.) 
  

  

  This 
  species 
  appears 
  to 
  be 
  near 
  Bothriocephalu^ 
  angusiiceps 
  Olsson.' 
  

   The 
  bothria 
  in 
  Olssoii's 
  species 
  are 
  said 
  to 
  be 
  marginal, 
  while 
  the 
  posi- 
  

   tion 
  of 
  the 
  genital 
  apertures 
  was 
  not 
  made 
  out. 
  It 
  is 
  therefore 
  not 
  

   possible 
  TO 
  refer 
  the 
  specimens 
  here 
  described 
  to 
  that 
  species. 
  

  

  Tiipe. 
  — 
  No. 
  4740, 
  U.S.iSr.jM. 
  Specimens 
  sent 
  to 
  me 
  by 
  Doctor 
  T. 
  

   H. 
  Bean 
  for 
  identification, 
  received 
  April 
  20, 
  1891. 
  The 
  specimens 
  

   were 
  taken 
  from 
  a 
  so 
  called 
  rock 
  cod 
  {Sehastodes 
  sp.) 
  at 
  Whatcom, 
  

   Washington. 
  

  

  The 
  bottle 
  contained 
  two 
  fragments 
  and 
  portion 
  of 
  pyloric 
  cceca 
  of 
  

   fish. 
  The 
  fragments 
  measured 
  190 
  and 
  310 
  mm. 
  in 
  length, 
  respectively. 
  

   Another 
  fragment 
  with 
  scolex 
  was 
  found 
  m 
  one 
  of 
  the 
  pyloric 
  coeca; 
  

   this 
  was 
  115 
  mm. 
  in 
  length. 
  

  

  Head 
  small, 
  elongated 
  truncate, 
  and 
  somewhat 
  capitate, 
  constricted 
  

   near 
  posterior 
  end 
  with 
  prominent 
  posterior 
  margin; 
  fossettes 
  coincide 
  

   with 
  tlat 
  surface 
  of 
  body 
  and 
  extend 
  posteriorly 
  nearly 
  to 
  constriction; 
  

   segments 
  begin 
  immediately 
  behind 
  head, 
  somewhat 
  funnel 
  shaped, 
  

   soon 
  becoming 
  densely 
  crowded 
  and 
  much 
  broader, 
  ten 
  to 
  twenty 
  or 
  

   more 
  times 
  as 
  broad 
  as 
  long, 
  decreasing 
  in 
  breadth 
  and 
  increasing 
  in 
  

   length 
  again 
  toward 
  posterior 
  end. 
  Posterior 
  segments 
  in 
  groui^s 
  of 
  

   three 
  or 
  four, 
  namely, 
  divisions 
  between 
  segments 
  of 
  contiguous 
  groups 
  

   more 
  distinctly 
  marked 
  than 
  between 
  other 
  adjacent 
  segments. 
  

  

  Dimensions 
  of 
  head 
  and 
  segments 
  : 
  Length 
  of 
  head, 
  1.30 
  mm. 
  ; 
  breadth 
  

   of 
  head, 
  apex, 
  0.40; 
  middle, 
  0.4G; 
  base, 
  0.40; 
  breadth 
  of 
  first 
  segment, 
  

   0.42; 
  length 
  of 
  first 
  segment, 
  0.12; 
  g-reatest 
  breadth, 
  5.5; 
  length 
  of 
  

   broadest 
  segments, 
  0.25; 
  breadth 
  of 
  posterior 
  end, 
  2; 
  length 
  of 
  poste- 
  

   rior 
  segments, 
  0.8. 
  

  

  Ova 
  large, 
  crowded 
  along 
  median 
  line 
  in 
  oval 
  or 
  pyriform 
  clusters. 
  

   Two 
  typical 
  ova 
  yielded 
  the 
  following 
  measurements 
  : 
  Length, 
  0.070 
  mm. 
  ; 
  

   breadth, 
  0.03S; 
  iength, 
  0.072; 
  breadth, 
  0.041. 
  

  

  The 
  sides 
  of 
  the 
  head 
  which 
  correspond 
  with 
  the 
  lateral 
  margins 
  of 
  

   the 
  body 
  are 
  median 
  ly 
  depressed 
  toward 
  anterior 
  end. 
  

  

  Only 
  mature 
  segments 
  were 
  sectioned, 
  in 
  which 
  the 
  uterus 
  with 
  its 
  

   contained 
  ova 
  obliterated 
  many 
  details 
  of 
  structure. 
  The 
  cirrus 
  and 
  

   vagina 
  open 
  by 
  a 
  common 
  aperture 
  on 
  the 
  middle 
  of 
  one 
  of 
  the 
  flat 
  

   surfaces 
  of 
  the 
  body. 
  This 
  surface 
  may 
  be 
  regarded 
  as 
  the 
  ventral 
  

   aspect 
  of 
  the 
  body. 
  The 
  vagina 
  is 
  behind 
  the 
  cirrus; 
  in 
  some 
  cases 
  

   directly 
  behind 
  it, 
  in 
  others 
  a 
  little 
  to 
  one 
  side 
  or 
  the 
  other 
  of 
  the 
  

   median 
  line. 
  The 
  cirrus 
  is 
  slender 
  and 
  the 
  muscular 
  pouch 
  has 
  rather 
  

   weak 
  walls. 
  A 
  central 
  vitelline 
  mass, 
  as 
  in 
  7>. 
  laciniainm, 
  and 
  vitelline 
  

   ducts 
  were 
  distinguished. 
  The 
  cells 
  of 
  the 
  ovary 
  are 
  very 
  large, 
  with 
  

   very 
  conspicuous 
  nuclei 
  in 
  carmine 
  stained 
  sections. 
  A 
  subglobular 
  

  

  'Lund'8 
  Uuiv. 
  Arsskr., 
  IX, 
  p. 
  12, 
  pi. 
  iii, 
  figs. 
  67-69. 
  

  

  