﻿104 
  PROCEEDINGS 
  OP 
  THE 
  NATIONAL 
  MUSEUM. 
  vol.44. 
  

  

  very 
  close 
  to 
  the 
  Atlantic 
  G. 
  hysoscela, 
  if 
  indeed 
  it 
  is 
  separable 
  from 
  

   it 
  at 
  all. 
  0. 
  melanaster, 
  too, 
  is 
  so 
  far 
  known 
  only 
  from 
  the 
  north- 
  

   western 
  Pacific; 
  and 
  the 
  Pelagia 
  is 
  a 
  representative 
  of 
  a 
  tropical 
  and 
  

   subtropical 
  genus, 
  a 
  casual 
  visitor 
  from 
  the 
  south. 
  , 
  

  

  Thus, 
  as 
  might 
  have 
  been 
  expected 
  on 
  oceanographic 
  grounds, 
  it 
  

   is 
  evident 
  that 
  the 
  medusa 
  fauna 
  of 
  the 
  Bering 
  Sea 
  region 
  has 
  been 
  

   recruited 
  from 
  two 
  directions, 
  there 
  being 
  a 
  constituent 
  from 
  the 
  

   warmer 
  waters 
  of 
  the 
  Pacific 
  on 
  the 
  one 
  hand 
  and, 
  on 
  the 
  other, 
  a 
  

   more 
  important 
  one, 
  numerically, 
  from 
  the 
  cold 
  Arctic 
  waters, 
  which 
  

   must 
  have 
  entered 
  Bering 
  Sea 
  by 
  way 
  of 
  Bering 
  Straits. 
  

  

  Most 
  of 
  the 
  leptoline 
  species 
  of 
  northern 
  origin 
  are 
  known 
  from 
  

   the 
  region 
  extending 
  from 
  Cape 
  Cod 
  to 
  southern 
  Labrador, 
  while 
  one, 
  

   Eutonina 
  socialis, 
  occurs 
  in 
  the 
  North 
  Sea; 
  that 
  is, 
  they 
  are 
  boreal 
  

   rather 
  than 
  purely 
  Arctic, 
  though 
  several 
  are 
  known 
  from 
  Arctic 
  

   stations; 
  and 
  this 
  is 
  what 
  we 
  might 
  have 
  expected, 
  for 
  in 
  summer 
  

   the 
  temperature 
  of 
  the 
  surface 
  waters 
  of 
  the 
  southern 
  part 
  of 
  Bering 
  

   Sea 
  is 
  from 
  50° 
  to 
  57°; 
  that 
  is, 
  about 
  as 
  warm 
  as 
  the 
  waters 
  of 
  the 
  

   northern 
  parts 
  of 
  the 
  Gulf 
  of 
  Maine 
  on 
  the 
  New 
  England 
  coast 
  and 
  

   considerably 
  warmer 
  than 
  the 
  surface 
  waters 
  of 
  the 
  Labrador 
  current 
  

   off 
  Labrador. 
  And 
  for 
  tliis 
  same 
  reason 
  it 
  is 
  probable 
  that 
  collec- 
  

   tions 
  made 
  during 
  the 
  late 
  summer 
  would 
  contain 
  a 
  greater 
  number 
  

   of 
  southern 
  species, 
  for 
  the 
  Fisheries 
  steamer 
  Albatross 
  records 
  are 
  

   limited 
  to 
  May 
  and 
  the 
  early 
  part 
  of 
  June. 
  

  

  The 
  Bering 
  Sea 
  list 
  includes 
  four 
  siphonophores, 
  all 
  long-known 
  

   species. 
  One 
  of 
  them, 
  DipJiyes 
  arctica, 
  previously 
  recorded 
  only 
  

   from 
  Arctic 
  and 
  boreal 
  regions 
  (19il&), 
  was 
  taken 
  regularly 
  on 
  the 
  

   present 
  cruise 
  in 
  cold 
  waters, 
  but 
  was 
  entirely 
  absent 
  in 
  the 
  warm 
  

   waters 
  of 
  the 
  Eastern 
  Sea 
  and 
  of 
  Kuro 
  shiro. 
  Like 
  the 
  Arctic 
  and 
  

   boreal 
  medusae, 
  it 
  probably 
  reached 
  the 
  Bering 
  Sea 
  region 
  from 
  the 
  

   north, 
  i. 
  e, 
  by 
  way 
  of 
  Bering 
  Straits. 
  But, 
  as 
  Doctor 
  Moser, 
  who 
  is 
  

   now 
  working 
  on 
  the 
  siphonophores 
  of 
  the 
  German 
  South 
  Polar 
  Expe- 
  

   dition, 
  writes 
  me 
  that 
  the 
  Gauss 
  took 
  it 
  in 
  many 
  localities, 
  further 
  

   discussion 
  of 
  its 
  distribution 
  is 
  best 
  postponed 
  until 
  her 
  data 
  is 
  

   published. 
  

  

  The 
  three 
  other 
  siphonophores 
  are 
  all 
  species 
  of 
  wide 
  distribution 
  

   in 
  both 
  Atlantic 
  and 
  Indo-Paoific, 
  Rosacea 
  plicata 
  and 
  Biphyes 
  trun- 
  

   cata 
  being 
  known 
  from 
  tropical 
  as 
  well 
  as 
  from 
  temperate 
  stations 
  

   and 
  Vogtia 
  pentacantlia 
  from 
  the 
  Bay 
  of 
  Biscay 
  and 
  from 
  the 
  Medi- 
  

   terranean. 
  But 
  as 
  none 
  of 
  them 
  has 
  ever 
  been 
  recorded 
  from 
  Arc- 
  

   tic 
  temperatures, 
  it 
  is 
  safe 
  to 
  assume 
  that 
  they 
  colonized 
  Bering 
  Sea 
  

   from 
  the 
  south. 
  They 
  were 
  all 
  taken 
  there 
  so 
  regularly 
  that 
  they 
  

   are 
  to 
  be 
  considered 
  characteristic 
  members 
  of 
  its 
  pelagic 
  fauna. 
  

  

  The 
  collection 
  suggests 
  the 
  probability 
  that 
  certam 
  species 
  of 
  

   medusae 
  belonging 
  to 
  intermediate 
  depths 
  may 
  be 
  confined 
  to 
  Arctic- 
  

   boreal 
  regions; 
  a 
  generalization 
  of 
  great 
  zoogeographic 
  interest 
  if 
  it 
  

  

  