﻿98 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM. 
  vol. 
  44. 
  

  

  sensory 
  pit 
  in 
  the 
  exiimbrella 
  above 
  the 
  sense 
  chib," 
  but 
  in 
  our 
  

   specimen 
  there 
  is 
  a 
  distinct 
  pit 
  above 
  each 
  rhopalium. 
  

   Color. 
  — 
  In 
  formalin 
  the 
  specimens 
  are 
  pale 
  yellowish. 
  

  

  Genus 
  A.URELIA 
  P^ron 
  and 
  Lesueur. 
  

  

  The 
  collection 
  contains 
  two 
  easily 
  distinguishable 
  species 
  of 
  Aurelia, 
  

   the 
  well-known 
  aurita, 
  and 
  the 
  Arctic 
  limhata 
  first 
  described 
  by 
  

   Brandt 
  (1838) 
  from 
  the 
  Bering 
  Sea 
  region. 
  As 
  Vanhoffen 
  has 
  

   pointed 
  out, 
  limbata 
  is 
  characterized 
  by 
  the 
  complex 
  branching 
  and 
  

   anastomosis 
  of 
  its 
  canal 
  system 
  and 
  by 
  pigmentation; 
  and 
  these 
  

   characters 
  taken 
  together 
  give 
  the 
  medusa 
  a 
  general 
  appearance 
  so 
  

   characteristic 
  that 
  it 
  is 
  identified 
  at 
  a 
  glance. 
  

  

  The 
  considerable 
  series 
  of 
  the 
  aurita 
  group 
  which 
  I 
  have 
  studied, 
  

   taken 
  oflF 
  the 
  coasts 
  of 
  New 
  England, 
  in 
  British 
  waters, 
  the 
  North 
  

   Sea, 
  Cuba, 
  Puget 
  Sound, 
  and 
  Japan, 
  all 
  incline 
  me 
  to 
  accept 
  Van- 
  

   hoffen's 
  view 
  that 
  they 
  can 
  not 
  be 
  divided 
  even 
  into 
  varieties, 
  cer- 
  

   tainly 
  not 
  by 
  the 
  precise 
  arrangement 
  of 
  the 
  canals. 
  According 
  to 
  

   Mayer 
  (1910, 
  p. 
  628) 
  "laUata^' 
  is 
  separable 
  from 
  aurita 
  by 
  the 
  fact 
  

   that 
  its 
  margin 
  is 
  cleft 
  into 
  16 
  instead 
  of 
  8 
  lappets, 
  by 
  the 
  small 
  diam- 
  

   eter 
  of 
  the 
  subgenital 
  openings, 
  and 
  because 
  the 
  bell 
  margin 
  " 
  projects 
  

   downward 
  from 
  the 
  subumbrella 
  side 
  as 
  8 
  plain-edged, 
  velum-Hke 
  

   folds 
  spanning 
  between 
  the 
  sense 
  organs." 
  But 
  our 
  8 
  specimens 
  

   from 
  Puget 
  Sound 
  and 
  Japan 
  show 
  very 
  clearly 
  that 
  whether 
  there 
  

   are 
  8 
  or 
  16 
  marginal 
  lobes 
  is 
  a 
  question 
  of 
  contraction. 
  In 
  some 
  few 
  

   preserved 
  specimens 
  the 
  margin 
  is 
  more 
  or 
  less 
  retracted 
  in 
  the 
  

   adradii, 
  giving 
  the 
  "lahiata" 
  outline; 
  in 
  others 
  the 
  contraction 
  has 
  

   taken 
  place 
  in 
  some 
  of 
  the 
  adradii 
  only; 
  and 
  one 
  specimen 
  from 
  Cuba 
  

   is 
  especially 
  instructive 
  because 
  there 
  are 
  four 
  such 
  false 
  lappets 
  

   in 
  one 
  octant. 
  

  

  The 
  size 
  of 
  the 
  subgenital 
  openings 
  seems 
  to 
  be 
  subject 
  to 
  great 
  

   variation 
  — 
  Mayer 
  himself 
  has 
  shown 
  very 
  small 
  ones 
  in 
  an 
  aurita 
  

   from 
  the 
  Tortugas 
  — 
  and 
  they 
  are 
  very 
  small 
  in 
  our 
  Japanese 
  speci- 
  

   mens 
  and 
  in 
  others 
  from 
  Cuba. 
  In 
  New 
  England 
  specimens 
  they 
  

   are 
  large 
  as 
  a 
  rule. 
  

  

  As 
  to 
  the 
  structure 
  of 
  the 
  margin, 
  I 
  may 
  point 
  out 
  that 
  it 
  is 
  exactly 
  

   the 
  same 
  in 
  aurita 
  as 
  it 
  is 
  described 
  by 
  Mayer 
  (1910) 
  for 
  lahiata; 
  in 
  

   both 
  the 
  tentacles 
  arise 
  some 
  distance 
  from 
  the 
  bell 
  margin, 
  and 
  the 
  

   intertentacular 
  lobes 
  are 
  not 
  discontinuous, 
  as 
  they 
  are 
  shown 
  in 
  L. 
  

   Agassiz's 
  beautiful 
  figures, 
  but 
  are 
  connected 
  with 
  one 
  another 
  below 
  

   the 
  tentacles 
  by 
  a 
  continuous 
  "shelf" 
  which 
  is 
  the 
  true 
  margin. 
  

   Below 
  this, 
  again, 
  the 
  velarium 
  is 
  situated. 
  

  

  There 
  are 
  two 
  Aurelias 
  besides 
  aurita 
  and 
  limhata, 
  which 
  may 
  per- 
  

   haps 
  deserve 
  specific 
  rank, 
  solida 
  Browne 
  and 
  maldivensis 
  'Bigelow, 
  

   the 
  former 
  characterized 
  by 
  the 
  vertical 
  position 
  of 
  the 
  rhopalia, 
  the 
  

   latter 
  by 
  the 
  extreme 
  development 
  of 
  the 
  mouth-arms. 
  But 
  both 
  of 
  

   these 
  demand 
  further 
  study. 
  

  

  