﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  SIPHONOPHORAE—BIGELOW. 
  47 
  

  

  Genus 
  CROSSOTA 
  Vanhoffen, 
  1902. 
  

  

  This 
  interesting 
  genus 
  was 
  founded 
  b}^ 
  Vanhoffen 
  for 
  a 
  Trachome- 
  

   dusa, 
  conspicuous 
  for 
  its 
  dense 
  pigmentation, 
  with 
  8 
  canals, 
  8 
  sausage- 
  

   shaped 
  gonads 
  hanging 
  from 
  the 
  canals 
  at 
  the 
  top 
  of 
  the 
  bell, 
  a 
  short, 
  

   broad 
  manubrium, 
  and 
  several 
  rows 
  of 
  tentacles 
  of 
  different 
  ages. 
  

   It 
  has 
  since 
  been 
  recorded 
  by 
  me 
  (1909a) 
  from 
  the 
  eastern 
  Pacific 
  expe- 
  

   dition 
  of 
  the 
  Fisheries 
  steamer 
  Albatross. 
  The 
  original 
  describer 
  and 
  

   Maas 
  (1906&) 
  grouped 
  Crossota 
  with 
  Ptychogastna 
  because 
  of 
  the 
  ar- 
  

   rangement 
  of 
  the 
  tentacles, 
  and 
  I 
  (1909a.) 
  followed 
  the 
  same 
  course, 
  

   though 
  pointing 
  out 
  that 
  it 
  lacks 
  the 
  mesenteries 
  of 
  PtycJiogastria, 
  

   while 
  the 
  tentacles 
  are 
  not 
  radially 
  grouped. 
  But 
  my 
  own 
  studies 
  on 
  

   PtycJiogastria 
  (1909c) 
  have 
  convinced 
  me 
  that 
  Crossota 
  has 
  no 
  relation- 
  

   ship 
  with 
  it, 
  because 
  the 
  gonads 
  in 
  PtycJiogastria 
  are 
  developed 
  in 
  the 
  

   walls 
  of 
  the 
  manubrium, 
  whereas 
  in 
  Crossota 
  they 
  are 
  borne 
  on 
  the 
  

   radial 
  canals. 
  Mayer 
  (1910) 
  groups 
  the 
  genus 
  with 
  Halicreas 
  and 
  

   Botrynema; 
  but 
  in 
  Crossota 
  the 
  manubrium 
  is 
  highly 
  organized, 
  with 
  

   distinct 
  digestive 
  and 
  labial 
  portions, 
  while 
  the 
  tentacles, 
  as 
  the 
  present 
  

   series 
  shows, 
  are 
  of 
  the 
  usual 
  Trachynemid 
  type, 
  instead 
  of 
  having 
  a 
  

   distal 
  spine 
  such 
  as 
  is 
  characteristic 
  of 
  Halicreas. 
  In 
  the 
  original 
  

   species 
  of 
  the 
  genus, 
  hrunnea, 
  the 
  tentacles 
  are 
  in 
  several 
  rows, 
  but 
  

   in 
  a 
  new 
  species 
  in 
  the 
  collection 
  this 
  arrangement 
  is 
  less 
  developed, 
  

   and 
  in 
  young 
  stages 
  (p. 
  49) 
  the 
  tentacles 
  are 
  in 
  a 
  single 
  row. 
  

  

  With 
  these 
  facts 
  in 
  view, 
  I 
  have 
  no 
  doubt 
  that 
  the 
  phylogenetic 
  

   relationship 
  of 
  Crossota 
  is 
  with 
  the 
  Trachynemidae, 
  and 
  especially 
  with 
  

   such 
  genera 
  as 
  AglantJia 
  and 
  Aglaura, 
  which 
  it 
  resembles 
  in 
  its 
  sense 
  

   organs, 
  its 
  gonads, 
  and 
  its 
  manubrium, 
  and 
  from 
  which 
  it 
  differs 
  only 
  

   in 
  the 
  arrangement 
  of 
  tentacles 
  in 
  the 
  adult. 
  

  

  Two 
  species 
  of 
  Crossota 
  were 
  described 
  by 
  Vanhoffen, 
  hrunnea, 
  the 
  

   type, 
  and 
  norvegica; 
  the 
  only 
  difference 
  between 
  the 
  two 
  being 
  that 
  

   the 
  latter 
  was 
  of 
  a 
  brighter 
  red 
  color 
  than 
  hrunnea 
  and 
  that 
  it 
  had 
  

   gonads, 
  though 
  smaller; 
  distinctions 
  so 
  slight 
  that 
  both 
  Mayer 
  (1910) 
  

   and 
  I 
  (1909a) 
  have 
  classed 
  norvegica 
  as 
  a 
  synonym 
  of 
  hrunnea. 
  But 
  the 
  

   present 
  collection 
  shows 
  that 
  I 
  went 
  too 
  far 
  in 
  uniting 
  them 
  unequivo- 
  

   cally, 
  for 
  it 
  contains 
  a 
  large 
  and 
  excellently 
  preserved 
  series 
  from 
  Ber- 
  

   ing 
  Sea, 
  all 
  of 
  the 
  ' 
  'norvegica" 
  type; 
  and 
  though 
  the 
  differences 
  between 
  

   them 
  and 
  hrunnea 
  are 
  slight, 
  the 
  characters 
  separating 
  them 
  from 
  the 
  

   latter 
  are 
  exactly 
  those 
  to 
  which 
  Vanhoffen 
  called 
  attention; 
  that 
  is, 
  

   rather 
  brighter 
  color 
  and 
  the 
  presence 
  of 
  gonads 
  in 
  smaller 
  speci- 
  

   mens, 
  to 
  which 
  I 
  may 
  add 
  fewer 
  tentacles 
  at 
  maturity. 
  Now 
  these 
  

   differences 
  are 
  so 
  slight 
  that 
  they 
  may 
  be 
  evidence 
  of 
  nothing 
  more 
  

   important 
  than 
  swarm 
  variation 
  such 
  as 
  is 
  so 
  prevalent 
  in 
  Aequorea. 
  

   But, 
  on 
  the 
  other 
  hand, 
  the 
  appearance 
  of 
  typical 
  norvegica 
  in 
  cold 
  

   waters 
  far 
  removed 
  from 
  its 
  type 
  locality 
  seems 
  rather 
  to 
  suggest 
  that 
  

   it 
  may 
  be 
  a 
  stable 
  form. 
  Before 
  we 
  can 
  answer 
  the 
  question 
  defi- 
  

  

  