﻿272 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol.96 
  

  

  gray-green; 
  posterior 
  third 
  pale 
  gray-green; 
  siphon, 
  pale 
  jade 
  green; 
  

   respiratory 
  gut, 
  translucent 
  raw 
  sienna. 
  

  

  T?/^g.— 
  U.S.N.M. 
  No. 
  19616. 
  

  

  Type 
  locality. 
  — 
  Elkhorn 
  Slough, 
  an 
  estuary 
  of 
  Monterey 
  Bay, 
  

   Calif. 
  ; 
  shallow 
  water, 
  muddy 
  sand. 
  

  

  Distribution. 
  — 
  California: 
  Humboldt 
  Bay, 
  Tomales 
  Bay, 
  Mon- 
  

   terey 
  Bay 
  (see 
  note 
  below), 
  Morro 
  Bay, 
  Newport 
  Bay. 
  With 
  one 
  

   exception 
  all 
  specimens 
  have 
  been 
  found 
  living 
  under 
  essentially 
  

   estuarial 
  conditions; 
  that 
  is, 
  in 
  quiet 
  bays 
  or 
  sloughs 
  in 
  sandy 
  mud. 
  

   As 
  a 
  rule 
  the 
  openings 
  of 
  the 
  burrows 
  are 
  under 
  water 
  at 
  low 
  tide, 
  

   but 
  are 
  sometimes 
  uncovered. 
  However, 
  in 
  June 
  1923 
  I 
  found 
  one 
  

   good-sized 
  specimen 
  in 
  a 
  bucket 
  holding 
  flounders 
  and 
  other 
  fish 
  

   caught 
  in 
  essentially 
  open 
  sea 
  conditions 
  near 
  the 
  Hopkins 
  Marine 
  

   Station, 
  Pacific 
  Grove, 
  Cahf. 
  This 
  record 
  points 
  to 
  the 
  probable 
  

   occurrence 
  of 
  the 
  species 
  at 
  moderate 
  depths 
  almost 
  anywhere 
  off 
  the 
  

   coast 
  of 
  Cahfornia 
  where 
  mud 
  of 
  the 
  proper 
  consistency 
  for 
  permanent 
  

   tunnels 
  is 
  present.^* 
  

  

  History. 
  — 
  The 
  first 
  specimens 
  of 
  which 
  I 
  have 
  any 
  knowledge 
  were 
  

   collected 
  in 
  1903 
  by 
  C. 
  S. 
  Thompson, 
  at 
  Morro 
  Bay, 
  Calif., 
  and 
  

   brought 
  to 
  Stanford 
  University. 
  Some 
  of 
  these, 
  in 
  a 
  good 
  state 
  of 
  

   preservation, 
  are 
  still 
  in 
  the 
  museum 
  there. 
  In 
  1920 
  I 
  found 
  one 
  

   specimen 
  in 
  Elkhorn 
  Slough, 
  Monterey 
  Bay, 
  where 
  a 
  few 
  years 
  later 
  

   Dr. 
  Myrtle 
  Johnson 
  collected 
  the 
  examples 
  from 
  wliich 
  the 
  figures 
  in 
  

   "Seashore 
  Animals 
  of 
  the 
  Pacific 
  Coast" 
  were 
  drawn. 
  In 
  1923 
  a 
  

   specimen 
  was 
  brought 
  in 
  by 
  flounder 
  fishermen 
  from 
  the 
  sea 
  bottom 
  

   off 
  the 
  Hopkins 
  Marine 
  Station. 
  It 
  was 
  not 
  until 
  1926 
  and 
  1927, 
  

   however, 
  that 
  the 
  animal 
  was 
  studied. 
  In 
  connection 
  with 
  an 
  

   ecological 
  exploration 
  of 
  Elkhorn 
  Slough, 
  Prof. 
  G. 
  E. 
  MacGinitie, 
  

   then 
  a 
  graduate 
  student 
  working 
  at 
  the 
  Hopldns 
  Marine 
  Station, 
  

   found 
  them 
  in 
  quantity. 
  By 
  means 
  of 
  narrow 
  aquaria 
  filled 
  with 
  mud 
  

   ("limoria") 
  and 
  glass-tube 
  facsimiles 
  of 
  the 
  actual 
  burrows, 
  he 
  was 
  

   able 
  to 
  observe 
  living 
  animals 
  under 
  essentially 
  normal 
  conditions, 
  

   for 
  Urechis 
  seems 
  to 
  be 
  insensible 
  to 
  light. 
  Every 
  important 
  fact 
  

   in 
  the 
  ecology 
  of 
  Urechis 
  has 
  been 
  discovered 
  by 
  Professor 
  Mac- 
  

   Ginitie.^^ 
  

  

  Habitat. 
  — 
  The 
  first 
  field 
  studies 
  were 
  made 
  at 
  Elkhorn 
  Slough, 
  a 
  

   shallow 
  estuary, 
  tributary 
  to 
  Monterey 
  Bay, 
  where 
  the 
  water, 
  al- 
  

   though 
  slightly 
  warmer 
  than 
  that 
  of 
  the 
  ocean 
  (which 
  here 
  varies 
  

   from 
  49° 
  to 
  57° 
  F.), 
  has 
  practically 
  the 
  same 
  salinity, 
  there 
  being 
  

   usually 
  a 
  free 
  interchange 
  with 
  each 
  tide. 
  In 
  this 
  inlet 
  dwell 
  a 
  con- 
  

   siderable 
  variety 
  of 
  bivalves, 
  some 
  of 
  which 
  are 
  much 
  sought 
  for 
  food. 
  

   There 
  are 
  two 
  very 
  interesting 
  decapods, 
  Callianassa 
  californiensis 
  

   Dana 
  and 
  Upogebia 
  pugettensis 
  (Dana) 
  , 
  which, 
  like 
  Urechis, 
  construct 
  

  

  " 
  Dr. 
  Earle 
  H. 
  Myers 
  tells 
  me 
  he 
  has 
  found 
  Urechis 
  in 
  the 
  stomach 
  of 
  dogfish 
  caught 
  northwest 
  of 
  San 
  

   Francisco 
  Bay 
  entrance 
  (Golden 
  Gate). 
  

   » 
  Fisher 
  and 
  MacGinitie, 
  1928b; 
  MacGinitie, 
  1935b, 
  pp. 
  682-686, 
  688, 
  715, 
  717; 
  1938, 
  p. 
  208. 
  

  

  