﻿44 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MU8EUM. 
  vol. 
  44. 
  

  

  Genus 
  RHOPALONEMA 
  Gegenbaur, 
  18S6. 
  

   RHOPALONEMA 
  VELATUM 
  Gegenbaur. 
  

   Rhopalonema 
  velatum 
  Gegenbaur, 
  1856, 
  p. 
  251, 
  pi. 
  9, 
  pp. 
  1-5. 
  

  

  ( 
  Kor 
  aynonymy, 
  see 
  Bigelow, 
  1909o, 
  p. 
  129, 
  and 
  Mayer, 
  1910, 
  p. 
  378.) 
  

  

  Station 
  4897, 
  150-0 
  fathoms; 
  3 
  specimens, 
  about 
  7 
  mm. 
  in 
  diametor. 
  

  

  Station 
  4020, 
  300-0 
  fathoms; 
  4 
  specimens, 
  6-9 
  mm. 
  in 
  dianictor. 
  

  

  Station 
  497S, 
  surface; 
  6 
  specimens, 
  8-10 
  mm. 
  in 
  diameter. 
  

  

  Station 
  5064, 
  300-0 
  fathoms; 
  2 
  specimens, 
  fi'agmentary. 
  

  

  Tlie 
  specimens 
  are 
  so 
  battered 
  that 
  it 
  is 
  impossible 
  to 
  add 
  anything 
  

   to 
  the 
  earlier 
  accounts 
  of 
  the 
  species 
  further 
  than 
  that 
  all 
  show 
  a 
  

   well-marked 
  apical 
  thickening 
  or 
  top 
  knot. 
  

  

  Genus 
  PANTACHOGON 
  Maas, 
  1893. 
  

  

  Homoeonema 
  Vanhoffen 
  (19026); 
  Mayer 
  (1910, 
  part). 
  

  

  Isonema 
  Maas 
  (1906«). 
  

  

  Not 
  Ilomoeonevia 
  Maas 
  (1893).— 
  Browne 
  (1903). 
  

  

  Trachynemidae 
  with 
  numerous 
  tentacles, 
  in 
  one 
  row, 
  and 
  all 
  alike; 
  

   without 
  peduncle. 
  

  

  The 
  genus 
  Isonema 
  was 
  instituted 
  by 
  Maas 
  for 
  two 
  species, 
  amplum 
  

   Vanhoffen 
  and 
  macrogaster 
  Vanhoffen, 
  in 
  which 
  the 
  gonads 
  are 
  spher- 
  

   ical 
  and 
  lie 
  close 
  to 
  the 
  manubrium. 
  But 
  studies 
  of 
  a 
  series 
  of 
  P. 
  

   haeckeli 
  have 
  convinced 
  me 
  that 
  the 
  precise 
  location 
  of 
  these 
  organs 
  

   on 
  the 
  canals 
  is 
  better 
  used 
  as 
  a 
  specific 
  character. 
  The 
  genus, 
  as 
  

   here 
  amplified, 
  includes 
  six 
  species, 
  Homoeonema 
  militare 
  Maas, 
  Ho- 
  

   moeonema 
  amplum 
  Vanlioffen, 
  Homoeonema 
  macrogaster 
  Vanhoffen, 
  

   PantacJiogon 
  ruhrumYsLnhoSen, 
  Pantachogon 
  scotti 
  Browne, 
  and 
  Pan- 
  

   tachogon 
  haeckeli 
  Maas, 
  the 
  last 
  being 
  the 
  type. 
  Homoeonema 
  pla- 
  

   tygonon 
  Maas 
  is 
  grouped 
  with 
  the 
  preceding 
  by 
  Mayer 
  (1910), 
  but 
  

   Maas 
  (19066) 
  has 
  pointed 
  out 
  that 
  its 
  type 
  specimen 
  belongs 
  to 
  a 
  

   different 
  family, 
  the 
  Halicreasidae. 
  

  

  The 
  position 
  of 
  the 
  gonads 
  separates 
  the 
  members 
  of 
  Pantachogon 
  

   into 
  three 
  groups, 
  amplum 
  and 
  macrogaster 
  in 
  which 
  they 
  are 
  close 
  

   to 
  the 
  manubrium; 
  militare 
  in 
  which 
  they 
  are 
  limited 
  to 
  the 
  distal 
  

   half 
  of 
  the 
  canals; 
  and 
  haeclceli, 
  scotti, 
  and 
  ruhrum, 
  in 
  which 
  they 
  

   occupy 
  nearly 
  the 
  whole 
  length 
  of 
  the 
  canals. 
  It 
  is 
  doubtful 
  whether 
  

   the 
  first 
  two 
  are 
  separable 
  from 
  each 
  other, 
  and 
  the 
  same 
  is 
  true 
  of 
  

   haeclceli 
  and 
  ruhrum, 
  which 
  can 
  be 
  told 
  apart 
  only 
  by 
  the 
  brilliant 
  

   red 
  color 
  of 
  the 
  latter. 
  Scotti 
  is 
  distinguished 
  from 
  the 
  last 
  two 
  by 
  

   its 
  more 
  numerous 
  tentacles 
  (about 
  120 
  instead 
  of 
  64). 
  

  

  PANTACHOGON 
  HAECKELI 
  Maas. 
  

   Plate 
  3, 
  %s. 
  4-8. 
  

  

  Pantachogon 
  haeckeli 
  Uaas, 
  1893, 
  p. 
  17, 
  pi. 
  J, 
  fit,'. 
  2; 
  1904, 
  p. 
  29.— 
  Mayer, 
  1910, 
  

   p. 
  389, 
  fig. 
  239. 
  

  

  Station 
  4758, 
  300-0 
  fathoms; 
  7 
  specimens. 
  

   Station 
  4760, 
  300 
  fathoms; 
  7 
  specimens. 
  

  

  