﻿224 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.98 
  

  

  as 
  having 
  two 
  pairs. 
  The 
  anal 
  vesicles 
  are 
  voluminous 
  with 
  numerous 
  

   conspicuous 
  ciliated 
  funnels. 
  The 
  ventral 
  blood 
  vessel 
  sends 
  an 
  

   important 
  branch 
  to 
  the 
  pharynx 
  and 
  esophagus. 
  

  

  For 
  this 
  species, 
  therefore, 
  I 
  propose 
  the 
  new 
  genus 
  Lissomyema, 
  

   which 
  differs 
  from 
  Thalassema 
  in 
  having 
  eight 
  well-differentiated 
  longi- 
  

   tudinal 
  muscle 
  bands 
  and 
  incipient 
  fasciculation 
  of 
  the 
  oblique 
  layer; 
  

   from 
  Listriolobus 
  and 
  Ochetostoma 
  in 
  having 
  simple 
  fan-shaped 
  nephro- 
  

   stome 
  without 
  trace 
  of 
  spiral 
  extensions. 
  Type, 
  Thalassema 
  mellita 
  

   Conn. 
  (Fig. 
  10.) 
  

  

  Ikedosoma 
  Bock. 
  — 
  Thalassema 
  elegans 
  Ikeda^ 
  does 
  not 
  belong 
  in 
  

   Thalassema. 
  Ikeda 
  (1907, 
  p. 
  50) 
  writes: 
  "All 
  the 
  longitudinal 
  lines 
  

   visible 
  on 
  the 
  outside, 
  excepting 
  the 
  one 
  which 
  runs 
  in 
  the 
  mid-ventral 
  

   line 
  and 
  is 
  superposed 
  by 
  the 
  nerve-cord, 
  appear 
  on 
  the 
  inner 
  surface 
  of 
  

   the 
  body-wall 
  as 
  slightly 
  elevated 
  narrow 
  ridges 
  or 
  thickenings 
  oj 
  the 
  

   longitudinal 
  muscular 
  layer. 
  In 
  the 
  ten 
  zones 
  separated 
  from 
  one 
  

   another 
  by 
  the 
  above 
  lines, 
  the 
  circular 
  muscle 
  fibres 
  form 
  more 
  or 
  

   less 
  regularly 
  arranged 
  transverse 
  bundles." 
  This 
  structure 
  of 
  the 
  

   body 
  wall 
  closely 
  approximates 
  that 
  of 
  Ochetostoma, 
  but 
  elegans 
  is 
  

   peculiar 
  in 
  having 
  numerous 
  (13 
  to 
  27) 
  nephridia 
  in 
  six 
  or 
  seven 
  

   pairs 
  of 
  groups 
  comprising 
  one 
  to 
  three 
  nephridia 
  each. 
  "The 
  internal 
  

   opening 
  present 
  at 
  base 
  is 
  provided 
  with 
  2 
  relatively 
  short 
  spiral 
  

   lobes." 
  The 
  dorsal 
  blood 
  vessel 
  ends 
  with 
  the 
  "heart" 
  on 
  the 
  hind 
  

   end 
  of 
  the 
  pharynx 
  and 
  is 
  therefore 
  shorter 
  than 
  in 
  typical 
  Echiuridae. 
  

   "The 
  neuro-intestinal 
  vessel 
  arises 
  from 
  the 
  ventral 
  median 
  point 
  of 
  

   the 
  ring-sinus, 
  which 
  surrounds 
  the 
  extreme 
  hind 
  end 
  of 
  pharynx" 
  

   {ibid., 
  p. 
  52). 
  There 
  is 
  no 
  interbasal 
  muscle 
  and 
  no 
  intestinal 
  coecum. 
  

  

  Thalassema 
  gogoshimense 
  Ikeda 
  (1904, 
  p. 
  66, 
  pi. 
  1, 
  fig. 
  19) 
  is 
  ap- 
  

   parently 
  congeneric 
  with 
  elegans. 
  The 
  excellent 
  colored 
  figure 
  shows 
  

   the 
  same 
  white 
  longitudinal 
  stripes 
  as 
  elegans, 
  reflecting 
  the 
  muscular 
  

   structure 
  of 
  body 
  wall. 
  Ikeda 
  says: 
  "It 
  shows 
  an 
  essential 
  agreement 
  

   with 
  Tlialassema 
  elegans. 
  Indeed, 
  the 
  agreement 
  may 
  be 
  said 
  to 
  be 
  

   complete, 
  the 
  only 
  difference 
  being 
  that 
  all 
  the 
  visceral 
  organs 
  in 
  the 
  

   present 
  species 
  are 
  developed 
  on 
  a 
  smaller 
  scale 
  in 
  proportion 
  to 
  the 
  

   smaller 
  size 
  of 
  its 
  body." 
  In 
  the 
  females, 
  however, 
  the 
  nephridia 
  

   are 
  present 
  in 
  three 
  pairs 
  all 
  situated 
  behind 
  the 
  setae, 
  while 
  in 
  the 
  

   male 
  they 
  are 
  in 
  six 
  to 
  eight 
  groups, 
  arranged 
  in 
  pairs, 
  each 
  group 
  

   with 
  one 
  to 
  four 
  nephridia, 
  which 
  are 
  like 
  those 
  of 
  elegans 
  in 
  structure. 
  

  

  The 
  above 
  paragraphs 
  were 
  written 
  and 
  a 
  name 
  was 
  assigned 
  to 
  

   the 
  genus 
  before 
  I 
  saw 
  Bock's 
  paper. 
  They 
  are 
  retained 
  since 
  we 
  

   independently 
  arrived 
  at 
  the 
  same 
  conclusion. 
  

  

  « 
  Ikeda, 
  1904, 
  p. 
  66; 
  1907, 
  p. 
  47, 
  pi. 
  1, 
  fig. 
  4; 
  pi. 
  4, 
  figs. 
  48, 
  49; 
  Sato, 
  1939, 
  p. 
  366; 
  Bock, 
  1942, 
  p. 
  18. 
  

  

  