﻿FRESH-WATER 
  TRICLADS 
  OF 
  ALASKA 
  — 
  ^KENK 
  

  

  167 
  

  

  European 
  species 
  such 
  as 
  P. 
  vitta 
  (Duges) 
  and 
  P. 
  albissima 
  (Vejdovsk^) 
  

   and 
  from 
  the 
  American 
  white 
  P. 
  morgani 
  (Stevens 
  and 
  Boring) 
  mainly 
  

   in 
  the 
  structm-e 
  of 
  the 
  male 
  copulatory 
  organ. 
  Asia 
  has 
  several 
  

   species 
  of 
  Phagocata, 
  the 
  majority 
  of 
  them 
  pigmented 
  forms. 
  Of 
  the 
  

   three 
  unpigmented 
  Asiatic 
  species 
  that 
  may 
  belong 
  to 
  the 
  genus, 
  two 
  

  

  Figure 
  21. 
  — 
  Phagocata 
  nivea, 
  diagram 
  ot 
  the 
  copulatory 
  organs 
  In 
  longitudinal 
  section, 
  

   X 
  92. 
  ac, 
  common 
  atrium; 
  am, 
  male 
  atrium; 
  b, 
  copulatory 
  bursa; 
  bd, 
  bursa 
  

   stalk; 
  Ip, 
  penis 
  lumen; 
  o, 
  mouth; 
  ode, 
  common 
  oviduct; 
  pg, 
  genital 
  pore; 
  vd, 
  vas 
  deferens. 
  

  

  have 
  been 
  described 
  from 
  immature 
  specimens 
  and 
  the 
  anatomy 
  of 
  

   their 
  reproductive 
  systems 
  is 
  not 
  known: 
  Planaria 
  pellucida 
  Ijima 
  

   and 
  Kaburaki 
  (1916) 
  from 
  Sakhalin 
  and 
  a 
  species 
  from 
  the 
  Bailial 
  

   region 
  assigned 
  tentatively 
  to 
  Fonticola 
  by 
  Bazikalova 
  (1947). 
  A 
  

   third 
  species, 
  Phagocata 
  coarctata 
  (Arndt, 
  1922), 
  from 
  the 
  vicinity 
  of 
  

   Vladivostok, 
  is 
  sufficiently 
  well 
  Imown, 
  although 
  no 
  fully 
  mature 
  

   individuals 
  of 
  this 
  species 
  have 
  been 
  studied. 
  P. 
  coarctata 
  differs 
  

   from 
  P. 
  nivea 
  externally 
  in 
  being 
  smaller 
  and 
  broader, 
  and 
  in 
  having 
  

   a 
  different 
  contour 
  of 
  the 
  anterior 
  end, 
  which 
  bears 
  protruding 
  lateral 
  

   lobes, 
  and 
  a 
  greater 
  distance 
  between 
  the 
  two 
  eyes. 
  Anatomically, 
  

   the 
  two 
  species 
  are, 
  undoubtedly, 
  closely 
  related.^ 
  

  

  ' 
  Livanov 
  and 
  Zabusova 
  (1940, 
  p. 
  146) 
  state 
  that 
  a 
  reexamination 
  of 
  Amdt's 
  slides 
  of 
  PUmaria 
  coarctata 
  

   showed 
  that 
  the 
  arrangement 
  of 
  the 
  muscle 
  fibers 
  of 
  the 
  pharynx 
  conformed 
  with 
  the 
  dendrocoelid 
  type 
  

   (circular 
  and 
  longitudinal 
  fibers 
  of 
  the 
  internal 
  muscle 
  zone 
  intermingled). 
  Amdt 
  (1922, 
  p. 
  108) 
  described 
  

   the 
  anatomy 
  of 
  the 
  pharynx 
  in 
  minute 
  detail 
  and 
  indicated, 
  both 
  in 
  a 
  figure 
  (pi. 
  4, 
  fig. 
  7) 
  and 
  in 
  the 
  text, 
  

   a 
  typical 
  planariid 
  pattern. 
  I 
  must 
  assume 
  that 
  some 
  confusion 
  occurred 
  somewhere, 
  probably 
  in 
  the 
  

   identification 
  of 
  the 
  slides 
  sent 
  to 
  Livanov. 
  

  

  