﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  SIPHONOPHORAE—BIGELOW. 
  49 
  

  

  young 
  stage 
  about 
  7 
  mm. 
  in 
  diameter; 
  but 
  they 
  could 
  not 
  be 
  found 
  

   in 
  the 
  adults 
  collected 
  by 
  the 
  Vdldivia 
  nor 
  in 
  the 
  eastern 
  Pacific 
  

   series. 
  Several 
  of 
  the 
  tentacles 
  of 
  the 
  best 
  specimen, 
  too, 
  are 
  intact, 
  

   though 
  most 
  of 
  them 
  are 
  broken 
  short 
  off, 
  as 
  has 
  been 
  the 
  invariable 
  

   rule 
  in 
  all 
  Crossotas 
  yet 
  described. 
  The 
  sense 
  clubs, 
  which 
  are 
  very 
  

   small 
  and 
  difficult 
  to 
  find 
  among 
  the 
  closely 
  crowded 
  tentacles, 
  have 
  

   a 
  single 
  terminal 
  concretion; 
  that 
  is, 
  they 
  are 
  of 
  the 
  usual 
  Trachyne- 
  

   mid 
  type. 
  I 
  could 
  not 
  count 
  them. 
  

  

  Tentacles. 
  — 
  In 
  the 
  best 
  specimen 
  there 
  are 
  about 
  43 
  tentacles 
  to 
  

   the 
  octant, 
  closely 
  crowded 
  together, 
  in 
  three 
  or 
  four 
  irregular 
  rows, 
  

   with 
  the 
  oldest 
  farthest 
  from 
  the 
  margin, 
  as 
  described 
  by 
  Vanhoffen. 
  

   It 
  is 
  impossible 
  to 
  distinguish 
  the 
  members 
  of 
  the 
  successive 
  series 
  of 
  

   development, 
  but 
  the 
  ones 
  most 
  recently 
  formed 
  lie 
  closest 
  to 
  the 
  

   margin, 
  and 
  there 
  are 
  some 
  so 
  young 
  that 
  they 
  are 
  still 
  mere 
  cirri. 
  

   In 
  Vanhoffen's 
  large 
  specimens 
  of 
  hrunnea 
  (32 
  mm. 
  in 
  diameter), 
  the 
  

   tentacles 
  were 
  more 
  numerous, 
  up 
  to 
  84 
  to 
  the 
  octant, 
  and, 
  of 
  course, 
  

   an 
  equally 
  large 
  number 
  n^ay 
  be 
  attained 
  in 
  norvegica, 
  for 
  we 
  have 
  

   no 
  right 
  to 
  assume 
  that 
  any 
  of 
  the 
  specimens 
  have 
  reached 
  their 
  final 
  

   dimensions. 
  Structurally 
  the 
  few 
  tentacles 
  which 
  remain 
  intact 
  are 
  

   of 
  the 
  usual 
  Trachynemid 
  type, 
  being 
  solid, 
  with 
  a 
  core 
  consisting 
  

   of 
  chordate 
  cells, 
  and 
  with 
  the 
  pigment 
  confined 
  to 
  the 
  entoderm. 
  In 
  

   a 
  specimen 
  4 
  mm. 
  in 
  diameter 
  the 
  tentacles, 
  though 
  of 
  different 
  sizes, 
  

   lie 
  in 
  a 
  single 
  row, 
  12, 
  13, 
  11, 
  in 
  three 
  successive 
  octants. 
  The 
  smallest 
  

   specimen 
  with 
  gonads 
  is 
  11 
  mm. 
  in 
  diameter; 
  in 
  specimens 
  15-20 
  mm. 
  

   the}^ 
  are 
  alinost 
  as 
  long 
  as 
  the 
  manubrium. 
  In 
  the 
  eastern 
  

   Pacific 
  series 
  of 
  hrunnea 
  the 
  smallest 
  specimen 
  with 
  gonads 
  is 
  17 
  mm. 
  

   in 
  diameter; 
  and 
  even 
  in 
  this 
  one 
  they 
  are 
  only 
  minute 
  swellings 
  on 
  

   the 
  radial 
  canals. 
  

  

  Color. 
  — 
  The 
  entire 
  subumbrella, 
  manubrium, 
  and 
  gonads 
  are 
  so 
  

   hea\dly 
  pigmented 
  vnth 
  chocolate-brown 
  as 
  to 
  be 
  practically 
  opaque. 
  

   The 
  tentacles, 
  too, 
  are 
  reddish-brown, 
  the 
  tint 
  being 
  rather 
  brighter 
  

   tlian 
  in 
  the 
  eastern 
  Pacific 
  specimens 
  of 
  hrunnea, 
  or 
  in 
  Vanhoffen's 
  

   (19026) 
  figure 
  of 
  the 
  latter. 
  The 
  manubrium 
  agrees 
  wirth 
  Vanhoffen's 
  

   account, 
  being 
  sessile 
  and 
  much 
  contracted 
  in 
  all 
  the 
  specimens. 
  

  

  One 
  of 
  the 
  interesting 
  things 
  which 
  the 
  series 
  shows 
  is 
  that 
  the 
  pig- 
  

   mentation 
  is 
  as 
  general 
  and 
  as 
  dense 
  in 
  specimens 
  4 
  and 
  5 
  mm. 
  in 
  

   diameter 
  as 
  it 
  is 
  in 
  larger 
  ones. 
  

  

  CROSSOTA 
  ALBA, 
  new 
  species. 
  

   Plate 
  3, 
  figs. 
  9-12. 
  

  

  Type.— 
  Cat. 
  No. 
  31056, 
  U. 
  S. 
  N. 
  M. 
  

   Station 
  4920, 
  300-0 
  fathoms; 
  1 
  specimen, 
  type. 
  

   Station 
  5050, 
  300-0 
  fathoms; 
  1 
  specimen. 
  

  

  The 
  specimens 
  are 
  both 
  about 
  22 
  mm. 
  iii 
  diameter 
  by 
  18 
  mm. 
  high, 
  

   with 
  deep 
  bell 
  cavity 
  and 
  comparatively 
  thin 
  gelatinous 
  substance. 
  

   69077°^Proc.N.M.vol.44— 
  13 
  i 
  

  

  