﻿PYCNOGONIDA 
  FROM 
  JAPANESE 
  WATERS 
  — 
  HEDGPETH 
  239 
  

  

  East 
  Indian 
  genera 
  found 
  in 
  Japanese 
  waters, 
  such 
  as 
  Pallenopsis 
  and 
  

   Ascorhynchus^ 
  are 
  rarely 
  reported 
  from 
  California 
  waters. 
  This 
  dif- 
  

   ference 
  in 
  the 
  distributional 
  effect 
  of 
  the 
  Pacific 
  and 
  Atlantic 
  currents 
  

   is 
  due 
  primarily 
  to 
  the 
  absence 
  of 
  large 
  rafts 
  of 
  sargassum 
  in 
  the 
  

   Pacific, 
  which 
  provide 
  a 
  convenient 
  agency 
  for 
  the 
  distribution 
  of 
  

   small 
  forms 
  in 
  the 
  North 
  Atlantic 
  (Hedgpeth, 
  1948, 
  p. 
  170). 
  This 
  is 
  

   emphasized 
  by 
  the 
  fact 
  that 
  there 
  are 
  no 
  species 
  of 
  Endeis 
  or 
  Ano- 
  

   plodactyJus 
  common 
  to 
  both 
  shores 
  of 
  the 
  North 
  Pacific, 
  as 
  is 
  the 
  case 
  

   in 
  the 
  North 
  Atlantic, 
  although 
  there 
  are 
  several 
  species 
  that 
  have 
  

   been 
  collected 
  in 
  tow 
  nets 
  in 
  Japanese 
  waters 
  (Ohshima, 
  1933c), 
  and 
  

   which 
  might 
  be 
  expected 
  to 
  have 
  a 
  wider 
  distribution 
  because 
  of 
  this 
  

   pelagic 
  habit. 
  

  

  There 
  appears 
  to 
  be 
  a 
  characteristic 
  pycnogonid 
  fauna 
  in 
  the 
  Bering 
  

   Sea, 
  including 
  a 
  northern 
  species 
  of 
  Pallenopsis 
  not 
  known 
  elsewhere, 
  

   one 
  or 
  two 
  species 
  of 
  Pseudopallene^ 
  and 
  several 
  endemic 
  Nymphons. 
  

   Some 
  of 
  the 
  Nymphons 
  and 
  Achelias 
  from 
  the 
  Bering 
  Sea 
  are 
  found 
  

   also 
  along 
  the 
  northern 
  Japanese 
  coast 
  and 
  probably 
  in 
  the 
  Japanese 
  

   Sea, 
  and 
  it 
  seems 
  likely 
  that 
  they 
  represent 
  dispersals 
  from 
  this 
  cold 
  

   water 
  area 
  via 
  the 
  O^^ashio. 
  The 
  interesting 
  Pycnosoma 
  strong 
  ylo- 
  

   centroti 
  is 
  probably 
  such 
  a 
  species, 
  since 
  it 
  has 
  been 
  found 
  in 
  the 
  Gulf 
  

   of 
  Tatary 
  and 
  off 
  Unalaska 
  (the 
  specimen 
  from 
  the 
  latter 
  locality 
  was 
  

   described 
  by 
  Hilton, 
  194:2c, 
  p. 
  40, 
  under 
  the 
  name 
  Pigrogromitus 
  

   rohu^tus). 
  

  

  Although 
  these 
  generalizations 
  are 
  based 
  solely 
  on 
  the 
  distribution 
  

   of 
  pycnogonids, 
  they 
  confirm 
  the 
  character 
  of 
  the 
  Japanese 
  marine 
  

   fauna 
  as 
  outlined 
  by 
  Ekman 
  (1935, 
  pp. 
  39-43). 
  His 
  conclusion 
  that 
  

   the 
  North 
  Pacific 
  littoral 
  fauna 
  (ibid., 
  p. 
  231) 
  is 
  six 
  to 
  eight 
  times 
  

   richer 
  than 
  the 
  North 
  Atlantic 
  holds 
  true 
  (although 
  in 
  lesser 
  degree) 
  

   for 
  the 
  pycnogonids, 
  as 
  it 
  does 
  for 
  the 
  decapods, 
  sea 
  stars, 
  and 
  fishes 
  

   on 
  which 
  it 
  was 
  based. 
  All 
  the 
  genera 
  containing 
  littoral 
  species 
  

   in 
  the 
  North 
  Atlantic 
  are 
  represented 
  in 
  the 
  North 
  Pacific, 
  several 
  of 
  

   them 
  with 
  many 
  more 
  species 
  than 
  in 
  the 
  Atlantic, 
  and 
  in 
  addition 
  

   there 
  are 
  at 
  least 
  three 
  genera, 
  Nytnphonella, 
  Decachela^ 
  and 
  Lecytho- 
  

   rhynchus, 
  endemic 
  to 
  the 
  North 
  Pacific. 
  Indeed, 
  there 
  is 
  but 
  one 
  

   authentic 
  endemic 
  genus 
  in 
  the 
  North 
  Atlantic, 
  Paranymphon^ 
  and 
  

   its 
  only 
  species 
  is 
  a 
  deep-water 
  form. 
  It 
  must 
  be 
  understood 
  that 
  

   these 
  remarks 
  do 
  not 
  hold 
  true 
  if 
  the 
  Caribbean 
  region 
  is 
  included 
  

   in 
  the 
  North 
  Atlantic, 
  for 
  insofar 
  as 
  present 
  knowledge 
  of 
  the 
  pycnog- 
  

   onid 
  fauna 
  of 
  comparable 
  regions 
  is 
  concerned, 
  the 
  Caribbean 
  ap- 
  

   jDears 
  to 
  be 
  somewhat 
  richer 
  than 
  the 
  East 
  Indies 
  in 
  number 
  of 
  genera 
  

   and 
  species. 
  These 
  remarks, 
  then, 
  apply 
  to 
  the 
  North 
  Atlantic 
  north 
  

   of 
  Florida 
  and 
  Cape 
  Verde 
  and 
  the 
  Pacific 
  from 
  Japan 
  northward 
  on 
  

   the 
  west 
  and 
  the 
  California 
  coast 
  on 
  the 
  east. 
  

  

  Recently 
  Gislen 
  (1943, 
  1944) 
  has 
  published 
  detailed 
  comparisons 
  of 
  

   the 
  coasts 
  of 
  California 
  and 
  Japan 
  at 
  comparable 
  latitudes. 
  The 
  most 
  

  

  