﻿262 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  The 
  nerve 
  cord 
  is 
  the 
  slenderest 
  I 
  have 
  seen 
  in 
  a 
  mature 
  echiuroid, 
  

   being 
  only 
  0.135 
  mm. 
  in 
  diameter. 
  

  

  The 
  gonad, 
  on 
  the 
  irregular 
  margin 
  of 
  a 
  mesentery 
  dorsal 
  to 
  nerve 
  

   cord, 
  is 
  invisible 
  except 
  under 
  high 
  magnification, 
  as 
  the 
  cells 
  are 
  

   small 
  and 
  inactive. 
  The 
  whitish 
  eggs 
  in 
  the 
  nephridia 
  are 
  0.5 
  to 
  

   0.6 
  mm. 
  in 
  diameter. 
  

  

  Anal 
  vesicles 
  are 
  in 
  the 
  form 
  of 
  numerous 
  slender 
  tubes 
  with 
  spaced 
  

   short 
  lateral 
  branches 
  (pi. 
  31, 
  fig. 
  6). 
  These 
  tubes 
  are 
  involved 
  in 
  

   and 
  fastened 
  to 
  body 
  wall 
  by 
  transparent 
  but 
  strong 
  frenula. 
  In 
  the 
  

   type 
  nearly 
  all 
  the 
  tubes 
  of 
  the 
  left 
  side 
  spring 
  from 
  a 
  small 
  irregular 
  

   common 
  chamber 
  closely 
  appressed 
  to 
  the 
  transparent 
  wall 
  of 
  the 
  

   cloaca, 
  but 
  oh 
  the 
  right 
  side 
  no 
  such 
  common 
  chamber 
  is 
  present. 
  

   Here 
  the 
  vesicular 
  tubes 
  arise 
  independently 
  from 
  the 
  cloacal 
  wall. 
  

   It 
  is 
  probable 
  that 
  the 
  number 
  of 
  tubes 
  increases 
  with 
  age. 
  The 
  

   ultimate 
  subdivisions 
  are 
  not 
  well 
  enough 
  preserved 
  for 
  exact 
  delinea- 
  

   tion 
  but 
  they 
  resemble 
  in 
  general 
  those 
  of 
  A. 
  ijimai. 
  Although 
  the 
  

   cloaca 
  is 
  not 
  perfect 
  in 
  any 
  of 
  the 
  specimens, 
  that 
  of 
  the 
  type 
  shows 
  a 
  

   rather 
  large 
  subspherical 
  chamber 
  with 
  transparent 
  walls 
  joined 
  to 
  the 
  

   body 
  wall 
  by 
  a 
  multitude 
  of 
  frenula. 
  

  

  Male. 
  Males 
  occur 
  in 
  the 
  genital 
  groove 
  as 
  shown 
  in 
  plate 
  31, 
  

   figure 
  2. 
  Probably 
  the 
  groove 
  is 
  normally 
  as 
  in 
  the 
  type, 
  which 
  has 
  

   one 
  or 
  two 
  males 
  in 
  it. 
  They 
  are 
  depressed 
  lanceolate 
  in 
  form, 
  1.2 
  

   mm. 
  long, 
  and 
  the 
  tube 
  of 
  the 
  sperm 
  receptacle 
  opens 
  at 
  the 
  middle 
  

   of 
  the 
  anterior 
  end, 
  the 
  receptacle 
  itself 
  being 
  about 
  in 
  the 
  middle 
  of 
  

   body 
  (pi. 
  31, 
  fig. 
  5). 
  

  

  TV^e.— 
  U.S.N.M. 
  No. 
  20601. 
  

  

  Type 
  locality. 
  — 
  Albatross 
  station 
  4942, 
  Kagoshima 
  Gulf, 
  Japan, 
  118 
  

   fathoms, 
  brown 
  mud, 
  black 
  specks, 
  bottom 
  temperature 
  59.8° 
  F., 
  

   2 
  specimens. 
  

  

  Specimens 
  examined. 
  — 
  The 
  above 
  and 
  1 
  specimen 
  (paratype) 
  from 
  

   station 
  4940, 
  same 
  locaHty, 
  115 
  fathoms 
  (pi. 
  31, 
  fig. 
  1). 
  

  

  Xenopneusta, 
  new 
  order 
  

  

  No 
  blood-vascular 
  system, 
  the 
  coelomic 
  fluid 
  being 
  heavily 
  charged 
  

   with 
  large 
  blood 
  corpuscles 
  containing 
  hemoglobin 
  or 
  hemoglobin 
  

   and 
  hematin; 
  intestine 
  with 
  terminal 
  portion 
  in 
  front 
  of 
  cloaca 
  en- 
  

   larged, 
  thm-walled, 
  functioning 
  as 
  an 
  organ 
  of 
  respiration 
  in 
  connection 
  

   with 
  anus 
  and 
  cloaca. 
  

  

  Family 
  URECHIDAE 
  Fisher 
  and 
  MacGinitie, 
  1928 
  

  

  Diagnosis. 
  — 
  Differing 
  from 
  other 
  Echiuroidea 
  in 
  the 
  absence 
  of 
  a 
  

   blood-vascular 
  system, 
  the 
  corpuscles 
  (red 
  or 
  brown 
  in 
  color 
  from 
  

   hemoglobin 
  or 
  hemoglobin 
  plus 
  hematin) 
  free 
  in 
  the 
  coelomic 
  

   fluid; 
  distal 
  portion 
  of 
  midgut 
  greatly 
  enlarged 
  and 
  in 
  connection 
  

   with 
  cloaca 
  serving 
  as 
  a 
  respiratory 
  apparatus; 
  foregut 
  very 
  long, 
  

  

  