﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  8IPH0N0PH0RAE—BI0EL0W. 
  

  

  89 
  

  

  Station 
  4970, 
  300-0 
  fathoms; 
  4 
  specimens. 
  

   Station 
  5079, 
  surface; 
  7 
  specimens. 
  

   Station 
  5081, 
  surface; 
  1 
  specimen. 
  

  

  The 
  localities 
  are 
  all 
  in 
  Japanese 
  waters 
  with 
  surface 
  temperatures 
  

   of 
  75°-86° 
  F. 
  

  

  Measurements 
  of 
  10 
  specimens, 
  21-60 
  mm. 
  in 
  diameter, 
  are: 
  

  

  These 
  measurements 
  show 
  that 
  fhere 
  is 
  a 
  good 
  deal 
  of 
  variation 
  in 
  

   the 
  proportional 
  lengths 
  of 
  manubrium 
  and 
  mouth 
  arms, 
  so 
  much 
  so 
  

   that 
  it 
  is 
  doubtful 
  whether 
  Maas's 
  (1903) 
  suggestion 
  that 
  panopyra 
  

   and 
  perla 
  are 
  separated 
  by 
  great 
  length 
  of 
  the 
  manubrium 
  in 
  the 
  

   former, 
  its 
  almost 
  entire 
  suppression 
  in 
  the 
  latter, 
  is 
  justified. 
  The 
  

   present 
  series 
  as 
  a 
  whole 
  seems 
  to 
  have 
  a 
  rather 
  longer 
  manubrium 
  

   than 
  the 
  specimens 
  recorded 
  by 
  Vanhoffen, 
  in 
  which 
  it 
  ranged 
  from 
  

   5-25 
  mm. 
  in 
  specimens 
  18-54 
  mm. 
  in 
  diameter. 
  But 
  in 
  deciding 
  

   how 
  much 
  weight 
  this 
  difference 
  deserves, 
  I 
  may 
  point 
  out 
  that 
  this 
  

   particular 
  measurement 
  is 
  not 
  a 
  reliable 
  one, 
  because 
  it 
  depends 
  very 
  

   largely 
  on 
  whether 
  the 
  manubrium 
  is 
  extended 
  or 
  contracted; 
  and 
  

   also 
  on 
  whether 
  it 
  is 
  stretched 
  when 
  the 
  measurement 
  is 
  taken. 
  To 
  

   make 
  the 
  measurements 
  of 
  the 
  present 
  series 
  comparable 
  with 
  one 
  

   another, 
  they 
  were 
  taken 
  with 
  the 
  manubrium 
  and 
  mouth 
  arms 
  

   stretched 
  out 
  straight. 
  

  

  The 
  shape 
  of 
  the 
  exumbral 
  nettle 
  knobs 
  is 
  the 
  main 
  feature 
  em- 
  

   ployed 
  by 
  Mayer 
  for 
  specific 
  diagnosis, 
  but 
  as 
  Vanhoffen 
  (1902a) 
  has 
  

   pointed 
  out, 
  the 
  types 
  intergrade. 
  In 
  the 
  first 
  place 
  there 
  is 
  not 
  a 
  

   single 
  specimen, 
  nor 
  have 
  I 
  ever 
  seen 
  one, 
  in 
  which 
  the 
  knobs 
  are 
  all 
  

   ahke; 
  but 
  in 
  every 
  one 
  round 
  knobs, 
  oval 
  ones, 
  linear 
  or 
  sausage-shaped 
  

   ones, 
  and 
  linear 
  ones 
  subdivided 
  by 
  transverse 
  furrows 
  are 
  to 
  be 
  seen. 
  

   In 
  specimens 
  from 
  Australia 
  and 
  from 
  Naples 
  the 
  same 
  variety 
  

   occurs; 
  but 
  in 
  the 
  three 
  large 
  specimens 
  of 
  the 
  Mediterranean 
  form, 
  

   '^noctiluca," 
  which 
  I 
  have 
  studied, 
  long 
  narrow 
  knobs 
  largely 
  pre- 
  

   dominate, 
  whereas 
  in 
  the 
  present 
  series 
  the 
  various 
  types 
  are 
  more 
  

   equally 
  represented. 
  In 
  our 
  small 
  specimens 
  14-20 
  mm. 
  in 
  diameter 
  

   most 
  of 
  the 
  knobs 
  are 
  round 
  or 
  oval, 
  and 
  they 
  are 
  much 
  higher 
  

   proportionately 
  than 
  in 
  the 
  larger 
  ones. 
  This 
  suggests 
  that 
  the 
  

  

  