﻿FXIIIUHOID 
  WORMS 
  OF 
  NORTH 
  PACIFIC 
  — 
  FISHER 
  265 
  

  

  obvious 
  that 
  Gay 
  has 
  the 
  mouth 
  and 
  anus 
  confused; 
  and 
  the 
  h'ngth 
  of 
  

   2 
  or 
  3 
  inches 
  is 
  small 
  for 
  the 
  average 
  size. 
  There 
  are 
  other 
  discrep- 
  

   ancies. 
  In 
  a 
  Lrcchis 
  3 
  inches 
  long, 
  the 
  anal 
  setae 
  are 
  not 
  "scarcely 
  

   visible" 
  but 
  are 
  conspicuous; 
  no 
  mention 
  is 
  made 
  of 
  the 
  prominent 
  

   anterior 
  setae; 
  no 
  specimen 
  of 
  Urcchis 
  displays 
  "hdcia 
  el 
  medio 
  inia 
  

   reunion 
  de 
  pequefios 
  cuerpos 
  dispuestos 
  en 
  una 
  banda 
  circular 
  de 
  una 
  

   linea 
  poco 
  6 
  menos 
  de 
  ancho," 
  whether 
  "medio" 
  refers 
  to 
  the 
  body 
  

   or 
  to 
  the 
  anus 
  (mouth), 
  which 
  just 
  precedes 
  this 
  sentence 
  in 
  the 
  

   description. 
  

  

  The 
  curious 
  respiratory 
  mechanism 
  of 
  Urechis, 
  in 
  connection 
  with 
  

   the 
  loss 
  of 
  its 
  blood 
  vessels 
  and 
  the 
  complexity 
  of 
  its 
  blood 
  physiology, 
  

   relegates 
  the 
  genus 
  to 
  a 
  very 
  isolated 
  position. 
  Not 
  less 
  important 
  is 
  

   the 
  behavior 
  pattern 
  whereby 
  the 
  requirements 
  of 
  respiration 
  and 
  

   food 
  are 
  beautifully 
  met 
  and 
  coordinated. 
  At 
  every 
  point 
  specializa- 
  

   tion 
  of 
  habit 
  is 
  matched 
  by 
  structural 
  and 
  physiological 
  adjustment 
  of 
  

   the 
  most 
  delicate 
  and 
  efficient 
  description. 
  Along 
  with 
  this 
  specializa- 
  

   tion 
  and 
  complexity 
  is 
  an 
  amazing 
  viability 
  best 
  expressed 
  by 
  the 
  

   term 
  "tough." 
  ^3 
  

  

  All 
  signs 
  point 
  to 
  Urechis 
  as 
  being 
  the 
  last 
  of 
  a 
  very 
  ancient 
  stock, 
  

   one 
  that 
  maj' 
  have 
  flowered 
  mto 
  many 
  species 
  during 
  Paleozoic 
  times. 
  

   It 
  belongs 
  to 
  the 
  honorable 
  company 
  of 
  Lingula 
  and 
  those 
  other 
  

   aristocrats 
  sometimes 
  refeiTcd 
  to 
  as 
  "living 
  fossils." 
  

  

  UnECHIS 
  CAUPO 
  Fteher 
  and 
  MacGlnitie 
  

  

  F1GCHE8 
  17-19; 
  Plates 
  33-35; 
  Plate 
  36, 
  Figures 
  2, 
  4; 
  Plate 
  37 
  

  

  Echiunia 
  sp. 
  Joh.nson 
  and 
  Snook, 
  1927, 
  p. 
  178, 
  fig. 
  153. 
  

  

  Urechis 
  caupo 
  Fisher 
  and 
  MacGinitie, 
  1928a, 
  p. 
  200, 
  pi. 
  9, 
  figs. 
  1-6; 
  1928b, 
  

  

  p. 
  204, 
  figs. 
  1-3, 
  pi. 
  10. 
  — 
  Baumbercer 
  and 
  Michaelis, 
  1931, 
  p. 
  417. 
  — 
  

  

  Reufield 
  and 
  Florkin, 
  1931, 
  p. 
  185.— 
  Hall, 
  1931, 
  p. 
  400.— 
  Sato, 
  1931, 
  p. 
  

  

  178.— 
  Newby, 
  1932, 
  p. 
  387; 
  1940; 
  1941, 
  p. 
  303.— 
  MacGinitie, 
  1935a, 
  p. 
  341; 
  

  

  1935b, 
  p. 
  002; 
  1935c, 
  p. 
  483; 
  1938, 
  j). 
  208. 
  

  

  Description. 
  — 
  The 
  species 
  reaches 
  a 
  large 
  size. 
  One 
  specimen 
  col- 
  

   lected 
  by 
  G. 
  E. 
  MacGinitie 
  at 
  Humboldt 
  Bay, 
  Calif., 
  measures 
  470 
  

   nmi. 
  long 
  by 
  55 
  mm. 
  thick. 
  The 
  largest 
  specnnen 
  from 
  Elkhorn 
  

   Slough, 
  Monterey 
  Bay, 
  Calif., 
  was 
  500 
  mm. 
  long 
  when 
  fully 
  relaxed 
  

   in 
  anesthesia, 
  but 
  after 
  preservation 
  it 
  shrank 
  to 
  375 
  mm. 
  in 
  length 
  

   i>y 
  35 
  mm. 
  in 
  diameter. 
  These 
  were 
  undoubtedly 
  very 
  old 
  individuals. 
  

   Average 
  specimens 
  are 
  150 
  to 
  180 
  mm. 
  long. 
  

  

  The 
  surface 
  of 
  the 
  body 
  is 
  traversed 
  by 
  fine 
  irregular 
  channels 
  giv- 
  

   ing 
  a 
  rugose 
  api)earance, 
  which 
  is 
  most 
  pronounced 
  in 
  the 
  head 
  region 
  

   anterior 
  to 
  the 
  zone 
  of 
  slime 
  glands. 
  The 
  latter, 
  a 
  sort 
  of 
  clitellum, 
  

   is 
  usually 
  distinguishable 
  by 
  the 
  circular 
  trend 
  of 
  its 
  fine 
  furrows. 
  

   Its 
  anterior 
  border 
  coijicides 
  roughly 
  with 
  the 
  second 
  j)air 
  of 
  nephiidia, 
  

  

  n 
  Sc« 
  Rc'indfl 
  and 
  Florkin, 
  1031; 
  nniimNrttcr 
  nnd 
  MIcharlLt, 
  1011; 
  Hall, 
  1931; 
  MncOlriitip, 
  103.15, 
  1935c; 
  

   Newhy, 
  IWO. 
  IWl; 
  Fisher 
  and 
  MncOlnltlo, 
  192«a. 
  

  

  