﻿258 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  tube 
  on 
  each 
  side 
  of 
  the 
  cloaca 
  to 
  which 
  very 
  numerous 
  small 
  trees 
  

   are 
  attached 
  at 
  approximately 
  the 
  same 
  point. 
  

  

  The 
  vascular 
  system 
  of 
  Nellobia 
  is 
  similar 
  to 
  that 
  of 
  Bonellia 
  and 
  

   allies 
  in 
  the 
  relation 
  between 
  the 
  dorsal 
  blood 
  vessel 
  and 
  the 
  neuro- 
  

   intestinal 
  trunk. 
  No 
  direct 
  connection 
  exists 
  between 
  the 
  two 
  by 
  

   obvious 
  anastomosis 
  of 
  terminal 
  branches 
  such 
  as 
  Danielssen 
  and 
  

   Koren 
  figure 
  (1881, 
  pi. 
  5, 
  fig. 
  14). 
  

  

  NELLOBIA 
  EUSOMA, 
  new 
  species 
  

  

  Plates 
  29, 
  30 
  

  

  Descrijption. 
  — 
  The 
  single 
  specimen 
  is 
  contracted 
  to 
  the 
  maximum 
  

   extent. 
  The 
  posterior 
  end 
  of 
  the 
  body 
  is 
  invaginated 
  to 
  form 
  a 
  cup- 
  

   shaped 
  depression 
  . 
  The 
  intestine 
  had 
  been 
  extruded, 
  after 
  the 
  manner 
  

   of 
  holothurians, 
  through 
  a 
  breach 
  in 
  the 
  cloacal 
  wall, 
  and 
  most 
  of 
  it 
  

   is 
  missing. 
  

  

  Body 
  of 
  ^OTigZZm 
  form 
  without 
  proboscis, 
  44 
  mm. 
  long 
  (allowing 
  for 
  

   posterior 
  invagination), 
  and 
  15-17 
  mm. 
  thick 
  at 
  middle. 
  Owing 
  to 
  

   contraction, 
  the 
  sldn 
  is 
  thrown 
  into 
  irregular 
  transverse 
  folds 
  with 
  

   frequent 
  pustulate 
  thickenings, 
  less 
  regular 
  in 
  the 
  anterior 
  ventral 
  

   region 
  (shown 
  in 
  pi. 
  29, 
  fig. 
  1) 
  than 
  elsewhere. 
  If 
  the 
  very 
  short 
  

   truncate 
  snout 
  is 
  the 
  remains 
  of 
  a 
  longer 
  proboscis, 
  it 
  is 
  nevertheless 
  

   covered 
  with 
  normal 
  skin. 
  The 
  conspicuous 
  opening 
  of 
  the 
  nephrid- 
  

   ium 
  is 
  close 
  to 
  the 
  median 
  line 
  about 
  4 
  mm. 
  behind 
  mouth. 
  

  

  The 
  body 
  wall 
  is 
  very 
  muscular 
  and 
  in 
  the 
  contracted 
  state 
  about 
  

   2 
  mm. 
  thick. 
  The 
  middle 
  longitudinal 
  layer 
  is 
  the 
  thickest, 
  the 
  

   inner 
  circular 
  layer 
  the 
  thinnest. 
  The 
  latter 
  in 
  the 
  contracted 
  state 
  

   of 
  the 
  specimen 
  shows 
  definite 
  fascicles 
  of 
  uneven 
  width 
  which 
  would 
  

   probably 
  smooth 
  out 
  when 
  the 
  worm 
  is 
  expanded. 
  

  

  The 
  single 
  neplmdium 
  (pi. 
  30) 
  is 
  attached 
  on 
  the 
  left 
  of 
  the 
  nerve 
  

   cord, 
  but 
  its 
  duct 
  passes 
  under 
  the 
  cord 
  to 
  open 
  in 
  the 
  median 
  line. 
  

   The 
  nephrostome 
  has 
  very 
  simple 
  lips 
  and 
  passes 
  into 
  a 
  bulbous 
  and 
  

   thick-walled 
  proximal 
  region. 
  The 
  distal 
  compartment, 
  filled 
  with 
  

   eggs, 
  has 
  the 
  wall 
  stretched 
  to 
  translucent 
  thimiess 
  but 
  its 
  proxunal 
  

   constricted 
  part 
  has 
  glandular 
  walls 
  furrowed 
  longitudinally. 
  There 
  

   is 
  a 
  definite 
  opening 
  from 
  the 
  egg 
  chamber 
  into 
  the 
  proximal 
  bulbous 
  

   portion. 
  

  

  The 
  anal 
  vesicles 
  are 
  peculiar. 
  Instead 
  of 
  having 
  a 
  roughly 
  treelike 
  

   foi-m 
  as 
  in 
  Bonellia 
  and 
  Bonelliopsis, 
  the 
  main 
  vesicle 
  is 
  a 
  sort 
  of 
  

   crescent-shaped 
  pouch 
  applied 
  to 
  each 
  side 
  of 
  the 
  large 
  cloacal 
  cavity 
  

   and 
  produced 
  on 
  the 
  opposite 
  or 
  free 
  border 
  into 
  numerous 
  (a 
  dozen 
  

   or 
  more) 
  unequal 
  dendritic 
  subdivisions. 
  The 
  larger 
  of 
  these 
  have 
  a 
  

   few 
  main 
  branches 
  lilve 
  a 
  tree, 
  which 
  in 
  turn 
  are 
  crowded 
  with 
  branch- 
  

   lets 
  (pi. 
  29, 
  fig. 
  4) 
  carrying 
  many 
  of 
  the 
  bulbous 
  glandular 
  elements 
  

   ending 
  each 
  in 
  a 
  ciliated 
  funnel. 
  Around 
  the 
  base 
  of 
  these 
  primary 
  

  

  