﻿FRESH-WATER 
  TRICLADS 
  OF 
  ALASKA 
  — 
  ^KENK 
  

  

  177 
  

  

  pharynx 
  intermingled 
  ; 
  no 
  adenodactyl 
  ; 
  penis 
  papilla 
  developed, 
  penis 
  

   bulb 
  of 
  simple 
  structure; 
  oviducts 
  unite 
  without 
  embracing 
  bursa 
  

   stalk; 
  zone 
  of 
  testes 
  extending 
  behind 
  the 
  level 
  of 
  the 
  copulatory 
  

   organs; 
  anterior 
  end 
  with 
  subterminal 
  true 
  sucker; 
  eyes 
  not 
  numerous 
  

   (Kenk, 
  1930). 
  Subsequently 
  Beauchamp 
  (1932, 
  p. 
  254) 
  founded 
  a 
  

   new 
  genus, 
  Amyadenium, 
  with 
  two 
  species, 
  A. 
  vandeli 
  Beauchamp 
  and 
  

   A. 
  brementi 
  (Beauchamp), 
  both 
  from 
  the 
  Pyrenees. 
  Two 
  more 
  

   species 
  were 
  reported 
  by 
  the 
  same 
  author 
  in 
  later 
  papers, 
  A. 
  chattoni 
  

   Beauchamp 
  (1949, 
  p. 
  60), 
  again 
  from 
  the 
  Pyrenees, 
  and 
  A. 
  garmieri 
  

   Beauchamp 
  (1950, 
  p. 
  65), 
  from 
  central 
  France. 
  Beauchamp 
  recog- 
  

   nized 
  the 
  close 
  relation 
  of 
  the 
  new 
  genus 
  to 
  Dendrocoelopsis, 
  but 
  

  

  Figure 
  23. 
  — 
  Dendrocoelopsis 
  piriformis, 
  diagram 
  of 
  the 
  copulatory 
  organs 
  in 
  longitudinal 
  

   section, 
  X 
  60. 
  am, 
  male 
  atrium; 
  b, 
  bursa; 
  bd, 
  bursa 
  stalk; 
  de, 
  ejaculatory 
  duct; 
  o, 
  mouth; 
  

   ode, 
  common 
  oviduct; 
  pg, 
  genital 
  pore; 
  vd, 
  vas 
  deferens; 
  vs, 
  seminal 
  vesicle. 
  

  

  separated 
  it 
  from 
  the 
  latter 
  on 
  accoimt 
  of 
  the 
  absence 
  of 
  a 
  highly 
  

   complex 
  grasping 
  organ, 
  or 
  true 
  sucker 
  (i. 
  e., 
  an 
  adhesive 
  organ 
  sepa- 
  

   rated 
  from 
  the 
  surrounding 
  mesenchyme 
  by 
  a 
  muscle 
  layer) 
  . 
  Hyman 
  

   (1935) 
  described 
  a 
  dendrocoelid 
  species 
  from 
  Montana 
  under 
  the 
  

   name 
  of 
  D. 
  vaginatus. 
  Again 
  the 
  main 
  characters 
  of 
  the 
  species 
  

   coincide 
  with 
  those 
  of 
  D. 
  spinosipenis 
  with 
  the 
  exception 
  of 
  the 
  

   grasping 
  organ, 
  which 
  is 
  of 
  a 
  simpler 
  type. 
  The 
  new 
  Alaskan 
  species, 
  

   D. 
  piriformis, 
  also 
  falls 
  clearly 
  in 
  the 
  vicinity 
  of 
  the 
  species 
  enumer- 
  

   ated, 
  as 
  does 
  another 
  species, 
  D. 
  alaskensis, 
  the 
  description 
  of 
  which 
  

   follows 
  on 
  p. 
  178. 
  Within 
  this 
  group 
  of 
  species 
  there 
  is 
  a 
  gradual 
  

   differentiation 
  of 
  the 
  grasping 
  organ, 
  which 
  is 
  absent 
  in 
  D. 
  alaskensis, 
  

   present 
  as 
  a 
  moderately 
  developed 
  adhesive 
  organ 
  in 
  D. 
  vaginata, 
  

   D. 
  piriformis, 
  A. 
  brementi, 
  A. 
  vandeli, 
  A. 
  chattoni, 
  and 
  A. 
  garmieri, 
  

   and 
  as 
  a 
  more 
  highly 
  developed 
  and 
  muscular 
  sucker 
  in 
  D. 
  spinosipenis. 
  

   A 
  similar 
  wide 
  variation 
  of 
  the 
  structure 
  of 
  the 
  anterior 
  grasping 
  organ 
  

  

  