﻿CESTODE 
  PARASITES 
  OF 
  FISHES— 
  LINTON. 
  451 
  

  

  broad. 
  The 
  remaining 
  rows 
  are 
  composed 
  of 
  hooks 
  which 
  are 
  more 
  

   slender 
  and 
  not 
  so 
  sharply 
  recurved. 
  There 
  is 
  not 
  a 
  very 
  great 
  diver- 
  

   sity 
  of 
  shape 
  and 
  size 
  in 
  the 
  hooks 
  in 
  this 
  species. 
  

   Dimensions 
  obtained 
  by 
  measurement 
  of 
  alcoholic 
  specimens. 
  

  

  42. 
  RHYNCHOBOTHRIUM 
  AGILE, 
  new 
  species. 
  

   (Plate 
  XXXIV, 
  tigs. 
  12-15.) 
  

  

  Tyi)e. 
  — 
  No. 
  4747, 
  U.S.N.M. 
  Bothria 
  elliptical, 
  divergent 
  at 
  base, 
  

   with 
  longitudinal 
  median 
  raised 
  septum; 
  neck 
  cylindrical, 
  short 
  when 
  

   compared 
  with 
  strobile, 
  which 
  is 
  very 
  long 
  and 
  slender; 
  proboscides 
  

   armed 
  with 
  exceedingly^ 
  small 
  hooks, 
  those 
  on 
  one 
  side 
  being 
  stouter 
  

   and 
  more 
  recurved 
  and 
  blunter 
  than 
  those 
  on 
  the 
  other 
  side, 
  more 
  slen- 
  

   der, 
  shorter, 
  straightish, 
  and 
  sharper 
  pointed; 
  segments 
  begin 
  near 
  

   base 
  of 
  contractile 
  bulbs 
  as 
  fine, 
  transverse 
  lines 
  ; 
  first 
  segments 
  con- 
  

   secpiently 
  very 
  short, 
  soon 
  becoming 
  squarish, 
  then 
  oblong, 
  ultimately 
  

   twice 
  as 
  long 
  as 
  broad 
  and 
  subcylindrical, 
  posterior 
  margins 
  slightly 
  

   flaring; 
  reproductive 
  aperture 
  near 
  middle 
  of 
  lateral 
  margin. 
  

  

  From 
  intestine 
  of 
  cow-nosed 
  ray 
  [RMnoptera 
  honasus); 
  Woods 
  

   Holl, 
  Massachusetts, 
  1880, 
  August 
  14, 
  two 
  specimens; 
  August 
  10, 
  oue 
  

   specimen. 
  

  

  Dimensions 
  of 
  living 
  specimen: 
  Length, 
  03 
  mm.; 
  breadth 
  of 
  head, 
  

   0.7; 
  length 
  of 
  bothrium, 
  0.40; 
  breadth 
  of 
  bothrium, 
  0.44; 
  diameter 
  of 
  

   neck, 
  0.4; 
  length 
  of 
  free 
  proglottides 
  with 
  ova, 
  4; 
  breadth 
  of 
  free 
  pro- 
  

   glottides, 
  1.5. 
  

  

  The 
  free 
  segments 
  were 
  almost 
  cylindrical. 
  When 
  placed 
  in 
  sea 
  

   water 
  one 
  of 
  them 
  was 
  seen 
  to 
  discharge 
  ova 
  from 
  one 
  end 
  in 
  a 
  dense 
  

   white 
  stream. 
  After 
  a 
  short 
  time 
  they 
  formed 
  a 
  mass 
  at 
  the 
  bottom 
  of 
  

   the 
  watch 
  glass. 
  The 
  color 
  of 
  the 
  mass 
  of 
  ova 
  changed 
  rapidly 
  from 
  

   white 
  to 
  very 
  bark-brown, 
  almost 
  black. 
  Some 
  of 
  the 
  ova 
  appear 
  

   nearly 
  globular, 
  others 
  measured 
  0.028 
  and 
  0.022 
  mm. 
  in 
  the 
  two 
  prin- 
  

   cii)al 
  diameters. 
  

  

  The 
  specimen 
  obtained 
  on 
  August 
  10 
  was 
  long 
  and 
  slender, 
  white, 
  

   very 
  active, 
  even 
  after 
  lying 
  twelve 
  hours 
  in 
  sea 
  water, 
  contracting 
  

   irregularly 
  and 
  throwing 
  itself 
  into 
  knots 
  and 
  coils 
  so 
  that 
  it 
  was 
  impos- 
  

   sible 
  to 
  get 
  satisfactory 
  measurements. 
  In 
  contracting, 
  tumid 
  places 
  

   are 
  succeeded 
  by 
  filiform 
  jilaces, 
  which 
  in 
  their 
  turn 
  may 
  quickly 
  become 
  

   tumid 
  again. 
  This 
  worm 
  was 
  still 
  active 
  nearly 
  twenty-four 
  hours 
  after 
  

   its 
  capture, 
  when 
  it 
  was 
  placed 
  in 
  picrosulphuric 
  acid. 
  It 
  was 
  broken 
  

   in 
  several 
  pieces 
  while 
  it 
  was 
  still 
  alive 
  in 
  endeavoring 
  to 
  dislodge 
  the 
  

   proboscides 
  from 
  a 
  segment 
  into 
  which 
  the 
  worm 
  had 
  thrust 
  them. 
  It 
  

   held 
  on 
  very 
  tenaciously 
  and 
  was 
  dislodged 
  with 
  the 
  greatest 
  difticulty. 
  

  

  Some 
  dimensions 
  of 
  alcoholic 
  specimen: 
  Breadth 
  of 
  head, 
  0.05 
  mm.; 
  

   length 
  of 
  bothrium, 
  0.45; 
  breadth 
  of 
  bothrium, 
  0.30; 
  diameter 
  of 
  neck, 
  

   0.30; 
  length 
  of 
  contractile 
  bulbs, 
  0.34; 
  length 
  of 
  head 
  and 
  neck, 
  1.23; 
  

   diameter 
  of 
  jiroboscis 
  exclusive 
  of 
  hooks, 
  0.03; 
  length 
  of 
  largest 
  hooks, 
  

   0.000; 
  length 
  of 
  last 
  segment, 
  1.5; 
  diameter 
  of 
  last 
  segment, 
  0.05. 
  

  

  