﻿ECHIUROID 
  WORMS 
  OF 
  NORTH 
  PACIFIC 
  — 
  FISHER 
  225 
  

  

  Genus 
  ECHIURUS 
  Gu^rin-iMeneville 
  

  

  Echiurus 
  GifRiN-MfiNEViLLK, 
  1831, 
  p. 
  9, 
  pi. 
  6, 
  fig. 
  3 
  (ex 
  Shipley, 
  1899, 
  p. 
  342) 
  

   (type, 
  Lumbricus 
  echiurus 
  TaUas, 
  1700= 
  Echiurus 
  pallasii 
  CUi<5rin-M<5nevilIe, 
  

   1831). 
  — 
  Skorikov, 
  1909, 
  p. 
  80. 
  — 
  Spengkl, 
  1912b, 
  p. 
  173. 
  

  

  Echiuriclae 
  with 
  two 
  rings 
  of 
  posterior 
  bristles, 
  a 
  well-developed 
  

   proboscis, 
  two 
  or 
  four 
  nepliridiii 
  (without 
  spirally 
  coiled 
  lips), 
  and 
  a 
  

   postpharj-ncjeal 
  tliaphragni, 
  which 
  separates 
  incompletely 
  the 
  small 
  

   liead 
  coelom 
  from 
  the 
  perivisceral 
  cavity. 
  

  

  ECHIURUS 
  ECHIURUS 
  ALASKANUS. 
  new 
  subspecies 
  

  

  Plate 
  20 
  

  

  Echiurus 
  Pallasii 
  C. 
  B. 
  Wilsov, 
  1900, 
  p. 
  174. 
  

   Echiurus 
  echiurus 
  Spengel, 
  1912b, 
  p. 
  183. 
  

  

  Diagnosis. 
  — 
  Differing 
  from 
  typical 
  E. 
  echiurus 
  (Pallas) 
  of 
  the 
  north 
  

   Atlantic 
  and 
  neighboring 
  Arctic 
  Ocean 
  in 
  having 
  the 
  proboscis 
  strongly 
  

   attached 
  to 
  the 
  body 
  and 
  in 
  having 
  the 
  posterior 
  setae 
  definitely 
  

   curved 
  lather 
  than 
  nearly 
  straight. 
  Length 
  of 
  type, 
  230 
  mm. 
  plus 
  

   much 
  contracted 
  proboscis, 
  20 
  mm. 
  

  

  Description. 
  — 
  ^Length 
  of 
  body 
  upward 
  of 
  230 
  mm., 
  commonly 
  100 
  

   mm., 
  stout; 
  proboscis 
  adherent, 
  fleshy, 
  convex 
  above, 
  the 
  edge 
  in- 
  

   curved 
  ventrally, 
  su})truncate 
  distally, 
  usually 
  15 
  to 
  20 
  mm. 
  long 
  in 
  

   contracted 
  state. 
  On 
  ventral 
  suHace 
  of 
  the 
  proboscis 
  a 
  difTcrentiated 
  

   thickening 
  extends 
  as 
  a 
  low 
  ridge 
  from 
  the 
  mouth 
  for 
  about 
  one- 
  

   fourth 
  length 
  of 
  proboscis 
  but 
  sometimes 
  considerably 
  farther. 
  The 
  

   integument 
  is 
  roughened 
  by 
  rings 
  of 
  prominent 
  vermcae 
  most 
  crowded 
  

   at 
  ends 
  of 
  body. 
  In 
  the 
  middle 
  region, 
  where 
  they 
  are 
  generally 
  

   loss 
  crowded, 
  rings 
  of 
  more 
  prominent 
  verrucac 
  alternate 
  with 
  zones 
  

   of 
  three 
  to 
  five 
  nngs 
  in 
  which 
  the 
  verrucac 
  are 
  smaller 
  or 
  more 
  widely 
  

   spaced, 
  or 
  both. 
  The 
  appearance 
  depends 
  largely 
  upon 
  the 
  degree 
  

   of 
  contraction 
  of 
  the 
  body 
  muscles. 
  

  

  The 
  anterior 
  setae 
  are 
  stout, 
  strongly 
  curved, 
  and 
  situated 
  back 
  of 
  

   the 
  base 
  of 
  proboscis 
  a 
  distance 
  e([ual 
  to 
  about 
  its 
  greatest 
  width. 
  In 
  

   each 
  circle 
  of 
  anal 
  bristles 
  there 
  may 
  be 
  variations 
  of 
  G 
  to 
  8, 
  as: 
  8-8 
  

   (posterior 
  ring); 
  8-7; 
  8-G; 
  7-7; 
  7-G. 
  In 
  some 
  specimens 
  where 
  the 
  

   number 
  is 
  less, 
  inequality 
  of 
  spacing 
  indicates 
  loss 
  of 
  setae. 
  These 
  

   pf)stcrior 
  setae 
  \t\ry 
  in 
  degree 
  of 
  curvatun* 
  but 
  are 
  slightly 
  more 
  

   curved 
  than 
  in 
  typical 
  A', 
  ecldurus. 
  The 
  anterior 
  setae 
  have 
  a 
  strong 
  

   interbasal 
  muscle 
  connecting 
  their 
  inner 
  ends. 
  Occasionally 
  a 
  second 
  

   seta, 
  in 
  process 
  of 
  formation, 
  a(;comi)anies 
  one 
  of 
  the 
  primary. 
  The 
  

   principal 
  posterior 
  muscle 
  from 
  the 
  setae 
  attaches 
  to 
  body 
  wall 
  just 
  

   behind 
  the 
  anterior 
  nephridium. 
  

  

  The 
  inner 
  circular 
  layr 
  of 
  body 
  muscle 
  shows 
  n 
  division 
  into 
  closely 
  

   placed 
  fascicles 
  at 
  each 
  end 
  of 
  body, 
  where 
  the 
  animal 
  is 
  nonnally 
  

   most 
  contracted. 
  

  

  