﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  SIPHONOPHORAE—BiaELOW. 
  7 
  

  

  Family 
  CYTAEIDAE 
  L. 
  Agassiz, 
  1862. 
  

   Genus 
  TURRITOPSIS 
  MeCrady, 
  1866. 
  

  

  The 
  most 
  recent 
  communication 
  on 
  this 
  genus 
  is 
  by 
  Hartlaub 
  

   (1911), 
  who 
  gives 
  a 
  discussion 
  of 
  the 
  three 
  members 
  of 
  the 
  genus 
  

   from 
  northern 
  waters, 
  polycirrlia 
  Keferstein, 
  nutricula 
  McCrady, 
  and 
  

   pacifica 
  Maas. 
  The 
  first 
  two 
  are 
  very 
  closely 
  allied 
  to 
  each 
  other, 
  so 
  

   much 
  so, 
  in 
  fact, 
  that 
  Mayer 
  (1910) 
  has 
  united 
  them. 
  . 
  Hartlaub, 
  

   arguing 
  to 
  the 
  contrary, 
  points 
  out 
  that 
  in 
  the 
  European 
  form 
  the 
  

   radial 
  canals 
  are 
  broader, 
  the 
  entodermal 
  "Zellpolster" 
  lower, 
  than 
  

   they 
  are 
  figured 
  by 
  Brooks 
  for 
  the 
  American 
  species 
  ; 
  that 
  the 
  radial 
  

   canals 
  are 
  not 
  dilated 
  within 
  the 
  ''Zellpolster," 
  that 
  the 
  latter 
  is 
  not 
  

   four-cornered, 
  and 
  finally 
  that 
  the 
  eggs 
  develop 
  into 
  planulae 
  within 
  

   the 
  bell 
  cavity, 
  something 
  which 
  has 
  never 
  been 
  observed 
  in 
  the 
  

   American 
  form. 
  But 
  Mayer's 
  (1910) 
  figure 
  of 
  an 
  adult 
  from 
  Newport 
  

   has 
  broad 
  canals, 
  and 
  these 
  are 
  not 
  enlarged 
  in 
  the 
  "Zellpolster." 
  I 
  

   have 
  myself 
  examined 
  specimens 
  from 
  Bermuda, 
  the 
  Tortugas, 
  and 
  

   Newport, 
  and 
  in 
  all 
  of 
  them 
  the 
  radial 
  canals 
  are 
  quite 
  as 
  broad 
  as 
  

   in 
  Busk's 
  figure 
  of 
  the 
  European 
  form 
  ; 
  and 
  in 
  no 
  case 
  do 
  the 
  canals 
  

   expand 
  within 
  the 
  "Zellpolster" 
  to 
  form 
  distinct 
  chambers 
  with 
  an 
  

   ascending 
  branch 
  such 
  as 
  Brooks 
  (1886) 
  observed, 
  though, 
  to 
  be 
  sure, 
  

   they 
  are 
  more 
  or 
  less 
  dilated. 
  Thus 
  it 
  appears 
  that 
  the 
  supposed 
  

   differences 
  between 
  polycirrlia 
  and 
  nutricula 
  are 
  so 
  unstable 
  as 
  to 
  be 
  

   worthless 
  for 
  specific 
  diagnosis, 
  and 
  as 
  Mayer 
  has 
  studied 
  many 
  

   nutricula 
  in 
  life, 
  I 
  believe 
  that 
  we 
  can 
  safely 
  follow 
  him 
  and 
  Maas 
  

   (1909) 
  in 
  uniting 
  the 
  two. 
  Pacifica 
  described 
  by 
  Maas 
  (1909) 
  as 
  

   var. 
  pacifica 
  of 
  nutricula, 
  is 
  distinguished 
  from 
  the 
  latter 
  by 
  large 
  

   size; 
  by 
  having 
  numerous 
  tentacles 
  arranged 
  in 
  several 
  rows, 
  and 
  

   especially 
  by 
  the 
  peculiarity 
  that 
  the 
  ocelli 
  lie 
  on 
  the 
  abaxial 
  instead 
  

   of 
  the 
  axial 
  faces 
  of 
  the 
  tentacular 
  bulbs; 
  and 
  these 
  differences 
  have 
  

   seemed 
  sufficient 
  both 
  to 
  Mayer 
  and 
  to 
  Hartlaub 
  to 
  show 
  that 
  

   pacifica 
  is 
  a 
  distmct 
  species. 
  

  

  The 
  present 
  collection 
  adds 
  to 
  our 
  knowledge 
  by 
  affording 
  two 
  

   perfectly 
  typical 
  specimens 
  of 
  nutricula 
  from 
  southern 
  Japan; 
  that 
  is, 
  

   from 
  the 
  same 
  general 
  region 
  as 
  pacifica. 
  It 
  was 
  of 
  course 
  so 
  inter- 
  

   esting 
  to 
  find 
  two 
  species 
  of 
  Turritopsis 
  in 
  Japanese 
  waters 
  that 
  I 
  

   paid 
  especial 
  attention 
  to 
  the 
  position 
  of 
  the 
  ocelli, 
  finding 
  that 
  there 
  

   is 
  an 
  axial 
  ocellus 
  on 
  each 
  tentacular 
  bulb 
  exactly 
  as 
  in 
  nutricula. 
  

   But 
  though 
  this 
  character 
  sharply 
  distinguishes 
  the 
  latter 
  from 
  

   pacifica, 
  number 
  and 
  arrangement 
  of 
  tentacles 
  do 
  not, 
  for 
  large 
  

   specimens 
  of 
  nutricula 
  have 
  70-85 
  or 
  more, 
  pacifica 
  about 
  120-150. 
  

   In 
  the 
  Albatross 
  specimens 
  they 
  are 
  apparently 
  in 
  two 
  rows, 
  but 
  in 
  

   reality 
  only 
  in 
  one, 
  the 
  appearance 
  being 
  due 
  to 
  differences 
  in 
  size 
  

   of 
  tentacles 
  of 
  different 
  ages, 
  and 
  to 
  crowding 
  and 
  contraction 
  of 
  the 
  

  

  