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  I'HOCIJEDIXCS 
  of 
  the 
  XJTIOXJL 
  museum. 
  v.-i. 
  w. 
  

  

  The 
  vitellaria 
  are 
  voluuiiiious, 
  i)eii[)lieial 
  in 
  posterior 
  region, 
  (leni- 
  

   tal 
  aperture 
  immediately 
  in 
  front 
  of 
  ventral 
  sucker. 
  Tbe 
  ova 
  were 
  not 
  

   numerous 
  in 
  any 
  of 
  the 
  specimens 
  examined 
  and 
  comparatively 
  large. 
  

   They 
  were 
  for 
  the 
  most 
  j^art 
  seen 
  lying 
  (jlose 
  behind 
  the 
  ventral 
  sucker, 
  

   though 
  a 
  few 
  were 
  seen 
  in 
  the 
  uterus 
  near 
  the 
  reproductive 
  aperture 
  

   in 
  front 
  of 
  that 
  organ; 
  long 
  diameter 
  of 
  ova, 
  0.08S; 
  short 
  diameter, 
  

   0,044 
  mm.; 
  length 
  of 
  posterior 
  testis, 
  O.L*7: 
  lengtli 
  of 
  anterior 
  testis, 
  

   0.24; 
  length 
  of 
  ovary, 
  0.12. 
  

  

  The 
  following 
  dimensions 
  are 
  of 
  a 
  living 
  example 
  slightly 
  compressed 
  : 
  

   Length, 
  2.9; 
  breadth, 
  anterior, 
  0.28; 
  at 
  ventral 
  sucker, 
  0.0; 
  near 
  pos- 
  

   terior 
  end, 
  0.54; 
  diameter 
  of 
  oral 
  sucker, 
  0.2G; 
  of 
  ventral 
  sucker, 
  O.'iS. 
  

   In 
  one 
  lot 
  the 
  specimens 
  in 
  life 
  varied 
  from 
  1.4 
  to 
  3.(! 
  mm. 
  in 
  length. 
  

   They 
  were 
  very 
  variable 
  in 
  shape. 
  

  

  Found 
  in 
  rectum 
  of 
  Rocoi.s 
  Uneatns; 
  Woods 
  Holl, 
  Massachusetts, 
  

   August 
  18, 
  1887, 
  and 
  August 
  3, 
  1889; 
  rather 
  numerous. 
  

  

  27. 
  DISTOMUM 
  TENUE 
  TENUISSIME. 
  new 
  subspecies. 
  

  

  (Plate 
  Lll, 
  Hus. 
  9-12.) 
  

  

  Body 
  slender, 
  linear 
  or 
  linear-lanceolate, 
  slightly 
  depressed 
  ; 
  mouth 
  

   terminal 
  armed 
  with 
  spines, 
  which 
  appear 
  to 
  be 
  evanescent: 
  neck 
  

   attenuate, 
  somewhat 
  concave 
  below, 
  crossed 
  by 
  tine 
  transverse 
  lines, 
  

   witli 
  evanescent 
  spines; 
  pharynx 
  large, 
  nearer 
  ventral 
  than 
  anterior 
  

   sucker; 
  ventral 
  sucker 
  nearly 
  twice 
  the 
  diameter 
  of 
  oral 
  sucker, 
  both 
  

   with 
  circular 
  apertures. 
  Testes 
  large, 
  in 
  posterior 
  third 
  of 
  body, 
  vitel- 
  

   laria 
  voluminous, 
  in 
  posterior 
  two-thirds 
  of 
  body, 
  obscuring 
  other 
  

   organs; 
  reproductive 
  aperture 
  in 
  front 
  of 
  ventral 
  sucker. 
  Ova 
  col- 
  

   lected 
  in 
  mass 
  near 
  center 
  of 
  body, 
  as 
  much 
  as 
  0.11 
  mm. 
  in 
  length 
  and 
  

   0.00 
  in 
  shorter 
  diamet:er. 
  

  

  Ti/pe.—^o. 
  48G5, 
  U.S.X.M. 
  

  

  Two 
  specimens, 
  3.75 
  and 
  4.5 
  mm. 
  in 
  length, 
  respectively, 
  from 
  the 
  

   peritoneum 
  of 
  the 
  white 
  perch 
  [Morone 
  americana), 
  ^\\\\e, 
  resembling 
  

   7). 
  tenne 
  in 
  many 
  particulars 
  do 
  not 
  admit 
  of 
  classification 
  with 
  that 
  

   species. 
  This 
  most 
  obvious 
  difference 
  is 
  the 
  much 
  more 
  slender 
  habit 
  

   of 
  body 
  of 
  the 
  si)ecimens 
  from 
  71/. 
  americava. 
  These 
  specimens 
  are 
  

   mature 
  and 
  have 
  nearly 
  smooth 
  bodies. 
  They 
  have 
  lost 
  some 
  of 
  the 
  

   (U'al 
  spines 
  also. 
  An 
  examination 
  of 
  more 
  abundant 
  material 
  might 
  

   warrant 
  the 
  uriion 
  of 
  the 
  two 
  varieties 
  in 
  the 
  species 
  J), 
  tenne. 
  

  

  The 
  ova 
  are 
  rather 
  numerous 
  and 
  very 
  irregular 
  in 
  size, 
  an 
  average 
  

   of 
  several 
  measurements 
  made 
  of 
  ova 
  from 
  the 
  largest 
  specimen 
  was, 
  

   long 
  diameter, 
  0.093, 
  short 
  diameter, 
  0.058 
  mm. 
  ; 
  the 
  smallest 
  seen 
  meas- 
  

   ured 
  0.04 
  by 
  0.02G 
  in 
  the 
  two 
  principal 
  diameters. 
  The 
  ova 
  in 
  one 
  of 
  

   the 
  specimens 
  were 
  observed 
  to 
  be 
  undergoing 
  segmentation. 
  

  

  The 
  following 
  dimensions 
  are 
  of 
  an 
  alcoholic 
  specimen 
  : 
  Length, 
  3.15 
  

   mm.; 
  di:i 
  meter 
  of 
  oral 
  sucker, 
  0.14; 
  diameter 
  of 
  ventral 
  sucker, 
  0.34; 
  

   distance 
  between 
  suckers, 
  0.67; 
  length 
  of 
  pharynx, 
  0.28; 
  diametor 
  of 
  

  

  