﻿ECHIUROID 
  WORMS 
  OF 
  NORTH 
  PACIFIC 
  — 
  FISHER 
  261 
  

  

  is 
  marked 
  by 
  flat 
  circular 
  spaced 
  spots 
  slightly 
  less 
  translucent 
  than 
  

   the 
  intervals. 
  Back 
  of 
  the 
  mouth 
  is 
  the 
  characteristic 
  genital 
  groove, 
  

   which 
  normally 
  is 
  probably 
  very 
  narrow 
  as 
  in 
  the 
  type 
  (pi. 
  31, 
  fig. 
  3) 
  

   but 
  in 
  the 
  paratype 
  (pi. 
  31, 
  figs. 
  2, 
  2a) 
  is 
  spread 
  apart 
  owing 
  to 
  

   stretching 
  of 
  l)ody 
  wall. 
  In 
  this 
  groove 
  are 
  four 
  males. 
  In 
  the 
  type 
  

   there 
  is 
  at 
  least 
  one. 
  At 
  the 
  posterior 
  end 
  of 
  groove 
  are 
  the 
  openings 
  

   of 
  the 
  nephridia: 
  two 
  in 
  the 
  type 
  and 
  another 
  specimen 
  (pi. 
  31, 
  figs. 
  

   4, 
  4(7); 
  one 
  in 
  the 
  paratype 
  (pi. 
  31, 
  figs. 
  1, 
  2). 
  The 
  hemispherical 
  

   papilla 
  sho\\Ti 
  in 
  these 
  figures 
  beside 
  the 
  nephridiopore 
  is 
  an 
  artifact. 
  

   Although 
  there 
  is 
  but 
  one 
  opening 
  there 
  are 
  two 
  large 
  iiepliridia 
  

   containing 
  eggs. 
  

  

  As 
  slated 
  above, 
  the 
  body 
  wall 
  is 
  very 
  thin, 
  on 
  the 
  order 
  of 
  0.15 
  to 
  

   0.2 
  mm. 
  thick, 
  and 
  a 
  single 
  thickness 
  is 
  so 
  transparent 
  that 
  printing 
  

   can 
  be 
  easily 
  read 
  through 
  it. 
  The 
  fibers 
  of 
  the 
  longitudinal 
  and 
  

   circular 
  muscles 
  can 
  be 
  seen 
  under 
  magnification, 
  but 
  there 
  are 
  no 
  

   bundles. 
  

  

  All 
  three 
  specimens 
  are 
  in 
  poor 
  condition 
  internally 
  as 
  the 
  midgut 
  

   and 
  hind-gut 
  are 
  badly 
  macerated, 
  the 
  contained 
  pellets 
  being 
  adrift 
  

   in 
  the 
  coelom. 
  The 
  more 
  essential 
  foregut 
  can 
  be 
  made 
  out 
  with 
  the 
  

   associated 
  blood 
  vessels. 
  

  

  The 
  nephridia, 
  in 
  good 
  condition, 
  number 
  two 
  in 
  all 
  three 
  speci- 
  

   mens. 
  They 
  have 
  exceedingly 
  thin 
  walls, 
  and 
  the 
  small 
  nephrostome 
  

   and 
  its 
  short 
  stalk 
  are 
  situated 
  at 
  the 
  base, 
  close 
  to 
  the 
  swollen 
  ducts 
  

   leading 
  to 
  nepliridiopores. 
  In 
  the 
  paratype 
  the 
  nephridia 
  are 
  about 
  

   twice 
  as 
  large 
  as 
  those 
  shown 
  on 
  plate 
  32. 
  

  

  The 
  significant 
  features 
  of 
  the 
  alimentary 
  canal 
  can 
  be 
  seen 
  on 
  

   plate 
  32. 
  The 
  pharynx 
  is 
  much 
  inflated 
  (but 
  probably 
  unnaturally) 
  

   and 
  has 
  very 
  thin 
  walls. 
  The 
  esophagus 
  can 
  be 
  traced 
  to 
  0' 
  where 
  

   the 
  fine 
  longitudinal 
  ridges 
  of 
  the 
  mucosa 
  change 
  to 
  equally 
  small 
  

   rings. 
  Then 
  follows 
  an 
  exceptionally 
  long 
  segment 
  of 
  the 
  foregut 
  

   in 
  which 
  I 
  can 
  find 
  no 
  marked 
  division 
  into 
  gizzard 
  and 
  stomach 
  (or 
  

   "crop"). 
  In 
  this 
  the 
  contents 
  are 
  shaped 
  into 
  oblong 
  pellets 
  1.5 
  to 
  

   2 
  mm. 
  long. 
  Extremely 
  slender 
  and 
  numerous 
  frcnula 
  connect 
  the 
  

   pliarynx 
  to 
  body 
  wall. 
  The 
  continuous 
  ventral 
  mesentery 
  of 
  foregut 
  

   is 
  delicate 
  and 
  transparent. 
  The 
  position 
  of 
  the 
  coils 
  of 
  foregut 
  in 
  

   figure 
  has 
  no 
  significance 
  as 
  they 
  had 
  mostly 
  broken 
  moorings. 
  All 
  

   the 
  foregut 
  is 
  thin-walled. 
  

  

  In 
  connection 
  witli 
  the 
  vascular 
  system 
  the 
  very 
  considerable 
  

   length 
  of 
  gut 
  between 
  attachment 
  of 
  dorsal 
  vessel 
  (/?') 
  and 
  ncuroin- 
  

   testinal 
  connective 
  {IP) 
  may 
  be 
  noted. 
  The 
  ventral 
  expansion 
  of 
  

   IP 
  is 
  considerably 
  farther 
  back 
  in 
  another 
  sj)ecimen. 
  In 
  keejMng 
  with 
  

   tiio 
  rest 
  of 
  the 
  animal 
  the 
  blood 
  vessels 
  arc 
  delicate 
  and 
  the 
  ventral 
  

   trunk 
  is 
  very 
  inconspicuous. 
  There 
  are 
  numerous 
  opaque 
  noduk'S 
  

   on 
  the 
  neurointestinal 
  trunk. 
  

  

  