﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  8IPH0N0PH0RAE—BIGEL0W. 
  101 
  

   Genus 
  CEPHEA 
  Peron 
  and 
  Lesueur, 
  1809. 
  

  

  Mayer 
  (1910) 
  has 
  given 
  an 
  excellent 
  account 
  of 
  this 
  genus, 
  and 
  has 
  

   pointed 
  out 
  that 
  since 
  in 
  all 
  known 
  species 
  of 
  Cephea 
  the 
  mouth-arms 
  

   "give 
  rise 
  to 
  secondary 
  dichotomous 
  or 
  dendritic 
  branches 
  and 
  all 
  

   are 
  laterally 
  compressed" 
  there 
  is 
  no 
  distinction 
  between 
  it 
  and 
  

   Netrostoma. 
  The 
  several 
  members 
  of 
  Cephea, 
  though 
  differing 
  widely 
  

   from 
  one 
  another 
  in 
  their 
  extremes, 
  are 
  connected 
  by 
  so 
  many 
  inter- 
  

   mediate 
  conditions 
  that 
  the 
  separation 
  of 
  the 
  species 
  is 
  difficult 
  and 
  

   probably 
  largely 
  artificial. 
  

  

  The 
  collection 
  contains 
  a 
  single 
  well-preserved 
  Cephea 
  which 
  agrees 
  

   very 
  well 
  with 
  the 
  C. 
  setouchiana 
  of 
  Kishinouye, 
  especially 
  in 
  having 
  

   a 
  rather 
  high 
  dome 
  with 
  numerous 
  protuberances, 
  and 
  a 
  unitary 
  

   four-lobed 
  subgenital 
  cavity, 
  a 
  character 
  which 
  it 
  shares 
  with 
  C. 
  coeru- 
  

   lescens 
  Maas. 
  According 
  to 
  Mayer, 
  setouchiana 
  is 
  a 
  variety 
  of 
  C. 
  

   cephea, 
  coerulescens 
  of 
  C. 
  octostyla, 
  the 
  two 
  species 
  being 
  separated 
  by 
  

   the 
  conformation 
  of 
  the 
  central 
  exumbral 
  dome. 
  This 
  character 
  is 
  a 
  

   variable 
  one, 
  as 
  INIayer 
  himself 
  has 
  found 
  ; 
  but 
  as 
  I 
  have 
  studied 
  only 
  

   a 
  single 
  specimen 
  of 
  the 
  genus, 
  his 
  classification 
  is 
  adopted 
  here 
  for 
  

   the 
  sake 
  of 
  uniformity. 
  Kishinouye's 
  account 
  (quoted 
  by 
  Mayer, 
  

   1910, 
  p. 
  657) 
  applies 
  so 
  well 
  to 
  our 
  specimen 
  that 
  no 
  description 
  is 
  

   called 
  for 
  here. 
  

  

  CEPHEA 
  CEPHEA 
  (ForskSl), 
  var. 
  SETOUCHIANA 
  (Kishinouye) 
  Mayer, 
  

   Microstylus 
  setouchianus 
  Kishinouye, 
  1902, 
  p. 
  11, 
  pla. 
  1, 
  2. 
  

   Netrostoma 
  setouchiaims 
  Browne, 
  1905a, 
  p. 
  967. 
  

   Cephea 
  cephea, 
  var. 
  setouchiana 
  Mayer, 
  1910, 
  p. 
  657, 
  fig. 
  409. 
  

  

  Nagasaki 
  Harbor, 
  August 
  5; 
  1 
  specimen, 
  80 
  mm. 
  in 
  diameter. 
  

  

  Genus 
  RHOPILEMA 
  Haeckel, 
  1880. 
  

  

  RHOPILEMA 
  ESCULENTA 
  Kishinouye. 
  

   rhopiUma 
  esculenta 
  Kishinouye, 
  18916, 
  p. 
  53; 
  1899, 
  p. 
  20, 
  pi. 
  13, 
  figs. 
  1-5. 
  — 
  Mayer, 
  

  

  1910, 
  p. 
  705, 
  fig. 
  423. 
  

   ? 
  Rhopilema 
  rhopalophora 
  Haeckel, 
  1880, 
  p. 
  596. 
  

  

  Kagoshima 
  Gulf, 
  Japan, 
  August 
  16, 
  surface; 
  1 
  excellent 
  specimen, 
  

   about 
  140 
  mm. 
  in 
  diameter. 
  

  

  Kishinouye's 
  (1899) 
  account 
  of 
  this 
  species, 
  quoted 
  by 
  Mayer, 
  is 
  so 
  

   good 
  that 
  no 
  description 
  is 
  necessary 
  here. 
  

  

  GEOGRAPHICAL 
  DISTRIBUTION. 
  

  

  The 
  chief 
  interest 
  of 
  the 
  collection, 
  from 
  the 
  zoogeographic 
  stand- 
  

   point, 
  is 
  that 
  it 
  throws 
  fresh 
  light 
  on 
  the 
  relationships 
  of 
  the 
  medusa 
  

   fauna 
  of 
  Bering 
  Sea 
  to 
  that 
  of 
  other 
  parts 
  of 
  the 
  north 
  Pacific 
  on 
  the 
  

   one 
  hand, 
  and 
  to 
  that 
  of 
  the 
  Ai-ctic 
  Ocean 
  and 
  north 
  Atlantic 
  on 
  the 
  

   other: 
  and 
  it 
  affords 
  our 
  first 
  information 
  of 
  the 
  siphonophore 
  fauna 
  

   of 
  the 
  northwestern 
  Pacific. 
  

  

  Some 
  40 
  species 
  of 
  medusae 
  are 
  now 
  recorded 
  from 
  the 
  region 
  

   including 
  Bering 
  Sea, 
  the 
  Aleutian 
  chain, 
  the 
  neighborhood 
  of 
  the 
  

   Shumagin 
  Islands, 
  and 
  the 
  east 
  coast 
  of 
  Kamchatka, 
  the 
  known 
  

  

  