﻿534 
  rnocKEDixas 
  of 
  the 
  national 
  miseum. 
  

  

  These 
  forms 
  have 
  many 
  points 
  of 
  reseuibli>uee 
  with 
  />. 
  nhjroflavum 
  

   and 
  indeed 
  agree 
  with 
  tlie 
  descriptions 
  of 
  tliat 
  si)ecies 
  in 
  one 
  or 
  two 
  

   l)articulars 
  in 
  which 
  the 
  specimens 
  referred 
  to 
  that 
  species 
  fail 
  to 
  agree, 
  

   notably 
  in 
  the 
  prominent 
  upper 
  lip 
  and 
  the 
  position 
  of 
  the 
  genital 
  

   aperture. 
  Whatever 
  may 
  be 
  the 
  proper 
  disposition 
  of 
  these 
  two 
  forms 
  

   as 
  to 
  designation, 
  there 
  is 
  no 
  doubt 
  in 
  my 
  mind 
  as 
  to 
  their 
  belonging 
  

   to 
  different 
  species. 
  The 
  thirty 
  specimens 
  of 
  1). 
  foliatum 
  and 
  tlic 
  

   thirteen 
  specimens 
  of 
  />. 
  nifirofiarHm, 
  altliougli 
  i)resenting 
  the 
  greatest 
  

   diversity 
  among 
  themselves, 
  make 
  two 
  distinct 
  groups 
  with 
  absolutely 
  

   no 
  hint 
  of 
  intermediate 
  forms. 
  

  

  The 
  Distoina 
  of 
  Mola 
  would 
  well 
  repay 
  a 
  careful 
  study. 
  Either 
  they 
  

   constitute 
  a 
  number 
  of 
  distinct 
  species 
  related 
  to 
  each 
  other 
  in 
  a 
  

   remarkable 
  way, 
  or 
  a 
  few 
  species 
  capable 
  of 
  the 
  most 
  astonishing: 
  

   variation. 
  

  

  25. 
  DISTOMUM 
  NITENS, 
  new 
  species. 
  

  

  (Plates 
  LI, 
  figs. 
  5, 
  (5; 
  LII, 
  fig. 
  1.) 
  

  

  Body 
  terete, 
  linear, 
  moderately 
  attenuate 
  both 
  posteriorly 
  and 
  ante- 
  

   riorly, 
  neck 
  about 
  one-third 
  entire 
  length, 
  conical, 
  variable 
  with 
  state 
  

   of 
  contraction, 
  armed 
  with 
  exceedingly 
  minute 
  bristle 
  like 
  spines; 
  

   mouth 
  subterminal, 
  ventral 
  sucker 
  larger 
  than 
  oral, 
  prominent 
  with 
  

   transverse 
  aperture. 
  Pharynx 
  prominent, 
  (esophagus 
  short 
  and 
  

   broad. 
  Cirrus 
  ])ouch 
  in 
  front 
  of 
  ventral 
  sucker 
  and 
  on 
  right 
  side 
  

   inclosing 
  a 
  part 
  of 
  the 
  vas 
  deferens 
  within 
  its 
  muscular 
  walls; 
  repro- 
  

   ductive 
  aperture 
  between 
  oral 
  and 
  ventral 
  suckers. 
  Vitellaria 
  a 
  num- 
  

   ber 
  of 
  roundish 
  masses 
  distributed 
  laterally 
  along- 
  the 
  middle 
  region 
  of 
  

   the 
  body. 
  Ovary 
  not 
  far 
  back 
  of 
  ventral 
  sucker, 
  globular; 
  testes 
  two, 
  

   rather 
  large, 
  situated 
  side 
  by 
  side 
  about 
  the 
  middle 
  of 
  the 
  body 
  or 
  a 
  

   little 
  back 
  of 
  the 
  middle. 
  Uterus 
  very 
  voluminous, 
  its 
  folds 
  tilling 
  all 
  

   the 
  posterior 
  third 
  of 
  the 
  body 
  and 
  the 
  greater 
  part 
  of 
  the 
  middle 
  third 
  

   tilled 
  with 
  small 
  elliptical 
  ova, 
  about 
  0.033 
  and 
  0.018 
  mm. 
  in 
  the 
  two 
  

   principal 
  diameters. 
  

  

  Tt/pc.—^o. 
  4858, 
  U.S.N.M. 
  

  

  Found 
  in 
  intestine 
  of 
  TyloHurus 
  <-<(ribba'u.s, 
  two 
  specimens; 
  Woods 
  

   Holl, 
  Massachusetts, 
  July 
  27, 
  1880, 
  

  

  The 
  following 
  measurements 
  were 
  made 
  on 
  a 
  living 
  specimen 
  : 
  Length, 
  

   2.8 
  mm.; 
  diameter 
  anterior, 
  0.28; 
  diameter 
  behiml 
  ventral 
  sucker, 
  0.0; 
  

   diameter 
  at 
  posterior 
  end, 
  O.l 
  ; 
  diameter 
  of 
  oral 
  sucker, 
  0.028; 
  diameter 
  

   of 
  ventral 
  sucker, 
  0.4; 
  distance 
  between 
  suckers, 
  0.0. 
  

  

  The 
  two 
  s])ecimens 
  had 
  been 
  subjected 
  to 
  some 
  pressure 
  during 
  the 
  

   })reliiuinary 
  examination, 
  during 
  which 
  they 
  became 
  much 
  altered 
  in 
  

   dimensions 
  from 
  the 
  foregoing. 
  The 
  sketch 
  (Fig. 
  5) 
  as 
  well 
  as 
  the 
  

   description 
  given 
  above 
  was 
  based 
  on 
  the 
  distorted 
  specimens. 
  The 
  

   alcoholic 
  specimens 
  measured 
  5 
  and 
  5.5 
  mm. 
  in 
  length, 
  respectively. 
  

   Otlier 
  dimensions 
  of 
  the 
  larger: 
  Median 
  breadth, 
  1.12 
  mm.; 
  diameter 
  

   of 
  oral 
  sucker, 
  0.47; 
  diameter 
  of 
  ventral 
  sucker, 
  0.06; 
  diameter 
  oi 
  

   phaiyn.x, 
  0.41; 
  distance 
  between 
  suckers, 
  1.04; 
  diameter 
  of 
  ovary, 
  0.45; 
  

  

  