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  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  los 
  

  

  Willow; 
  road 
  from 
  Anchorage 
  to 
  Potter; 
  and 
  Richardson 
  Highway, 
  

   section 
  between 
  Valdez 
  and 
  Glenallen. 
  

  

  No 
  fresh-water 
  triclads 
  were 
  found 
  by 
  me 
  either 
  at 
  Point 
  Barrow 
  

   or 
  at 
  Umiat. 
  I 
  received, 
  however, 
  from 
  the 
  U. 
  S. 
  National 
  Museum, 
  

   a 
  sample 
  of 
  triclads 
  collected 
  by 
  P. 
  F. 
  Scholander 
  in 
  a 
  lake 
  near 
  Umiat. 
  

   The 
  relative 
  scarcity 
  of 
  planarians 
  in 
  tundra 
  lakes 
  and 
  pools 
  may 
  be 
  

   due 
  to 
  the 
  high 
  acidity 
  of 
  the 
  waters 
  or 
  to 
  the 
  extremely 
  severe 
  con- 
  

   ditions 
  prevailing 
  in 
  them 
  during 
  the 
  long 
  winter 
  season. 
  

  

  Grateful 
  acknowledgment 
  is 
  made 
  of 
  the 
  very 
  helpful 
  cooperation 
  

   which 
  was 
  extended 
  to 
  me 
  by 
  several 
  agencies 
  in 
  Alaska: 
  The 
  Arctic 
  

   Research 
  Laboratory, 
  Point 
  Barrow; 
  the 
  U. 
  S. 
  Public 
  Health 
  Service, 
  

   Anchorage; 
  the 
  Alaska 
  Road 
  Commission, 
  Fairbanks, 
  Anchorage, 
  and 
  

   Glenallen; 
  and 
  the 
  Division 
  of 
  Forestry, 
  Bureau 
  of 
  Land 
  Management, 
  

   Fairbanks 
  and 
  Anchorage. 
  I 
  also 
  wish 
  to 
  express 
  my 
  indebtedness 
  to 
  

   Prof. 
  Edward 
  G. 
  Reinhard 
  of 
  the 
  Catholic 
  University 
  of 
  America 
  and 
  

   to 
  Dr. 
  Fenner 
  A. 
  Chace, 
  Jr., 
  and 
  Dr. 
  Doris 
  M. 
  Cochran 
  of 
  the 
  U. 
  S. 
  

   National 
  Museum 
  who 
  kindly 
  permitted 
  me 
  to 
  use 
  their 
  laboratory 
  

   and 
  office 
  facilities 
  in 
  Washington, 
  D. 
  C. 
  

  

  Four 
  species 
  of 
  fresh-water 
  triclads 
  were 
  collected 
  in 
  Alaska. 
  Two 
  

   are 
  inhabitants 
  of 
  the 
  White 
  Mountains, 
  a 
  mountain 
  range 
  extending 
  

   in 
  an 
  east-west 
  direction 
  north 
  of 
  Fairbanks. 
  The 
  other 
  two 
  are 
  

   widely 
  distributed 
  in 
  waters 
  of 
  the 
  Alaska 
  Range 
  and 
  of 
  the 
  southern 
  

   section 
  of 
  Alaska 
  and 
  one 
  of 
  them 
  reaches 
  as 
  far 
  north 
  as 
  Umiat. 
  

  

  Family 
  Planariidae 
  

   Genus 
  Phagocata 
  Leidy 
  

  

  Phagocata 
  niveau 
  new 
  species 
  

  

  Figure 
  21; 
  Plate 
  6, 
  Figure 
  1 
  

  

  Description. 
  — 
  This 
  is 
  a 
  slender, 
  rather 
  delicate 
  species. 
  Mature 
  

   specimens 
  measure 
  up 
  to 
  8 
  mm. 
  in 
  length 
  and 
  about 
  L5 
  mm. 
  in 
  width. 
  

   In 
  the 
  quietly 
  gliding 
  animal 
  the 
  anterior 
  end 
  is 
  truncated,with 
  a 
  very 
  

   slightly 
  bulging 
  frontal 
  outline 
  and 
  with 
  rounded 
  lateral 
  corners 
  

   (auricles) 
  . 
  There 
  is 
  no 
  distinct 
  narrowing 
  or 
  neck 
  behind 
  the 
  auricles 
  

   and 
  the 
  lateral 
  margins 
  of 
  the 
  head 
  are 
  approximately 
  parallel. 
  Behind 
  

   the 
  head, 
  the 
  body 
  widens 
  and 
  soon 
  reaches 
  its 
  greatest 
  width. 
  From 
  

   there 
  on, 
  the 
  lateral 
  margins 
  of 
  the 
  body 
  run 
  parallel 
  up 
  to 
  the 
  level 
  

   of 
  the 
  mouth, 
  to 
  converge 
  agam 
  in 
  the 
  postpharyngeal 
  region 
  and 
  to 
  

   meet 
  in 
  a 
  bluntly 
  pointed 
  posterior 
  end. 
  

  

  The 
  species 
  lacks 
  pigment 
  and 
  usually 
  appears 
  white 
  and 
  somewhat 
  

   transparent. 
  The 
  intestinal 
  contents 
  may 
  shine 
  through 
  the 
  body 
  

   wall 
  and 
  give 
  the 
  animal 
  a 
  certain 
  amount 
  of 
  color; 
  the 
  margins 
  of 
  the 
  

   body, 
  the 
  head 
  region, 
  and 
  the 
  areas 
  occupied 
  by 
  the 
  pharynx 
  and 
  the 
  

   copulatory 
  apparatus, 
  however, 
  are 
  always 
  white. 
  

  

  