﻿234 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  tinuous 
  sheet 
  between 
  the 
  longitudmal 
  bands, 
  not 
  divided 
  into 
  

   separate 
  fascicles. 
  Nephridia 
  2 
  or 
  3 
  pairs; 
  interbasal 
  muscle 
  of 
  setae 
  

   present. 
  

  

  The 
  character 
  of 
  the 
  longitudinal 
  muscles 
  is 
  not 
  well 
  marked 
  in 
  L. 
  

   pelodes 
  until 
  the 
  animal 
  has 
  reached 
  a 
  length 
  of 
  15 
  to 
  20 
  mm. 
  and 
  

   after 
  it 
  is 
  sexually 
  mature. 
  Apparently 
  in 
  L. 
  sorbillans 
  (Lampert) 
  a 
  

   similar 
  condition 
  exists 
  (Wharton, 
  1913). 
  Even 
  so, 
  the 
  structure 
  of 
  

   the 
  nephrostome 
  will 
  segregate 
  these 
  species 
  from 
  true 
  Thalassema. 
  

   L. 
  riukiuensis 
  (Sato, 
  1939, 
  p. 
  359, 
  figs. 
  10-13) 
  is 
  probably 
  not 
  a 
  

   Listriolobus. 
  There 
  is 
  no 
  interbasal 
  muscle 
  to 
  setae; 
  the 
  diagram 
  of 
  

   the 
  blood 
  vessels 
  is 
  not 
  the 
  Listriolobus 
  pattern. 
  

  

  Spengel 
  (1912c, 
  p. 
  316) 
  established 
  Listriolobus 
  for 
  Thalassema 
  

   erythrogrammon 
  of 
  Sluiter 
  (1883) 
  and 
  of 
  Wilson 
  (1900). 
  Sluiter's 
  

   species 
  came 
  from 
  BHliton 
  in 
  the 
  Java 
  Sea 
  whUe 
  Wilson's 
  was 
  taken 
  

   in 
  the 
  Bahamas, 
  Spengel 
  had 
  Sluiter's 
  animal 
  and 
  a 
  duplicate, 
  from 
  

   Florida, 
  of 
  Wilson's 
  species, 
  which 
  he 
  characterized 
  as 
  "nearly 
  re- 
  

   lated." 
  Unfortunately, 
  as 
  neither 
  of 
  these 
  species 
  had 
  a 
  valid 
  name, 
  

   Listriolobus 
  was 
  without 
  a 
  type 
  and 
  was 
  technically 
  a 
  nomen 
  nudum, 
  

   Spengel 
  did 
  mention 
  Thalassema 
  mellita 
  Conn 
  as 
  a 
  species 
  inquirenda, 
  

   "which 
  species 
  one 
  must 
  include 
  in 
  the 
  above 
  genus 
  I 
  can 
  not 
  at 
  

   present 
  decide, 
  nor 
  even 
  whether 
  or 
  not 
  it 
  is 
  justifiable 
  to 
  include 
  

   such 
  a 
  form 
  as 
  Th. 
  mellita, 
  which 
  has 
  bundles 
  of 
  longitudinal 
  muscles 
  

   that 
  arise 
  from 
  thickenings 
  of 
  the 
  continuous 
  longitudinal 
  muscle 
  

   layer." 
  A 
  few 
  lines 
  farther 
  on 
  he 
  says: 
  "The 
  animals 
  described 
  by 
  

   Sluiter 
  and 
  Wilson 
  as 
  Thalassema 
  should 
  be 
  put 
  in 
  the 
  same 
  genus 
  

   with 
  Th. 
  mellita 
  because 
  of 
  the 
  nature 
  of 
  the 
  sheaths 
  surrounding 
  the 
  

   tunic 
  muscles. 
  I 
  propose 
  the 
  generic 
  name 
  Listriolobus 
  for 
  the 
  species 
  

   of 
  Sluiter 
  and 
  Wilson." 
  

  

  Wilhelm 
  Fischer 
  (1926a, 
  p. 
  110) 
  discusses 
  Listriolobus 
  and 
  names 
  

   Wilson's 
  and 
  Sluiter's 
  species 
  Listriolobus 
  bahamensis 
  and 
  L. 
  billi- 
  

   tonensis. 
  So 
  far 
  as 
  I 
  know 
  this 
  is 
  the 
  first 
  association 
  of 
  Listriolobus 
  

   with 
  a 
  species 
  from 
  which 
  a 
  type 
  can 
  be 
  chosen. 
  Since 
  Fischer 
  did 
  

   not 
  do 
  this 
  I 
  will 
  so 
  designate 
  Listriolobus 
  bahamensis 
  Fischer, 
  as 
  

   being 
  the 
  species 
  more 
  likely 
  to 
  be 
  available 
  for 
  study 
  in 
  the 
  future. 
  

   By 
  implication 
  Fischer 
  includes 
  Th. 
  mellita 
  Conn 
  in 
  Listriolobus, 
  but 
  

   I 
  have 
  made 
  it 
  the 
  type 
  of 
  a 
  new 
  genus, 
  Lissomyema. 
  

  

  LISTRIOLOBUS 
  PELODES. 
  new 
  species 
  

  

  Figures 
  12, 
  13; 
  Plate 
  21, 
  Figures 
  1, 
  2, 
  4, 
  4a, 
  4b; 
  Plate 
  22 
  

  

  Description. 
  — 
  Largest 
  specimens 
  40-60 
  mm. 
  long 
  and 
  12-25 
  mm. 
  

   thick; 
  proboscis 
  capable 
  of 
  extension 
  to 
  slightly 
  exceeding 
  length 
  of 
  

   body, 
  narrow, 
  thin, 
  translucent, 
  so 
  that 
  nerve 
  loop 
  is 
  visible. 
  

  

  Body 
  wall 
  tanslucent, 
  marked 
  by 
  eight 
  narrow 
  longitudinal 
  muscular 
  

   thickenings 
  which 
  appear 
  light 
  gray 
  agamst 
  the 
  darker 
  and 
  much 
  

   broader 
  areas 
  between 
  them. 
  There 
  are 
  a 
  middorsal 
  and 
  midventral 
  

  

  