﻿NO. 
  1946. 
  PACIFIC 
  MEDUSAE 
  AND 
  8IPH0N0PH0RAE—BIGEL0W. 
  

  

  91 
  

  

  p. 
  583), 
  but 
  Mayer 
  (1910) 
  has 
  already 
  pointed 
  out 
  that 
  the 
  number 
  

   of 
  tentacles 
  to 
  the 
  octant 
  in 
  the 
  type 
  species 
  lactea 
  L. 
  Agassiz 
  may 
  

   be 
  more 
  than 
  five, 
  and 
  in 
  a 
  considerable 
  number 
  of 
  lactea, 
  and 
  as 
  the 
  

   following 
  table 
  shows, 
  it 
  is 
  the 
  rule, 
  not 
  the 
  exception, 
  to 
  find 
  more 
  

   than 
  five 
  tentacles 
  to 
  the 
  octant. 
  

  

  Dactylometra 
  lactea, 
  Santiago, 
  Cuba. 
  

  

  On 
  examining 
  the 
  individual 
  octants 
  it 
  was 
  at 
  once 
  evident 
  that 
  

   when 
  there 
  were 
  only 
  five 
  tentacles, 
  the 
  ones 
  nearest 
  the 
  ocular 
  lobes 
  

   were 
  usually 
  the 
  youngest; 
  but 
  when 
  there 
  were 
  more, 
  the 
  others 
  

   were 
  irregularly 
  interpolated. 
  This, 
  of 
  course, 
  shows 
  that 
  it 
  is 
  

   impossible 
  to 
  distinguish 
  Kuragea 
  with 
  seven, 
  from 
  Dactylometra 
  with 
  

   five 
  tentacles 
  to 
  the 
  octant; 
  and 
  as 
  we 
  do 
  not 
  yet 
  know 
  what 
  the 
  

   limit 
  to 
  tentacle 
  formation 
  is 
  in 
  D. 
  lactea, 
  we 
  may 
  define 
  Dactylometra 
  

   as 
  Pelagidae 
  with 
  five 
  or 
  more 
  tentacles 
  to 
  the 
  octant. 
  

  

  The 
  various 
  species 
  of 
  Dactylometra 
  are 
  distinguished 
  from 
  one 
  

   another 
  only 
  by 
  such 
  minor 
  characters 
  as 
  color, 
  number 
  of 
  tentacles, 
  

   and 
  form 
  of 
  the 
  marginal 
  lappets, 
  features 
  all 
  more 
  or 
  less 
  variable. 
  

   The 
  Pacific 
  forms, 
  ferruginaster 
  Kishinouye 
  and 
  pacijlca 
  Gotte, 
  are 
  

   undoubtedly 
  merely 
  successive 
  stages 
  in 
  the 
  development 
  of 
  one 
  

   species 
  (IMaas, 
  1909), 
  in 
  which, 
  as 
  the 
  present 
  collection 
  shows, 
  five 
  

   tentacles 
  per 
  octant 
  are 
  attained 
  in 
  specimens 
  of 
  about 
  40 
  mm. 
  in 
  

   diameter. 
  In 
  large 
  specimens 
  of 
  this 
  species 
  accessory 
  tentacles 
  

   appear 
  (D. 
  longicirrlm 
  Kishinouye), 
  and 
  in 
  its 
  final 
  condition 
  there 
  

   are 
  seven 
  tentacles 
  per 
  octant 
  {Kuragea 
  depressa 
  Kishinouye). 
  

  

  According 
  to 
  Kishinouye, 
  the 
  tentacles 
  are 
  short 
  in 
  ferruginaster, 
  

   long 
  in 
  pacifica 
  { 
  = 
  longicirr'ha 
  K!ishinouye), 
  but 
  my 
  series 
  of 
  lactea 
  

   and 
  the 
  Japanese 
  Dactylometras 
  in 
  the 
  present 
  collection 
  show 
  that 
  

   there 
  is 
  too 
  much 
  variability 
  in 
  this 
  respect 
  and 
  that 
  it 
  is 
  too 
  sub- 
  

   ject 
  to 
  contraction 
  to 
  be 
  used 
  in 
  classification. 
  D. 
  africana 
  Van- 
  

   hoffen, 
  which 
  has 
  five 
  tentacles 
  per 
  octant 
  when 
  very 
  large, 
  seems 
  to 
  

   be 
  allied 
  to 
  quinquecirrlia, 
  in 
  which 
  there 
  are 
  never 
  more 
  than 
  five, 
  

   often 
  less; 
  indeed, 
  the 
  only 
  thing 
  definitely 
  separating 
  it 
  from 
  the 
  

   latter 
  is 
  its 
  brilHant 
  coloration. 
  For 
  an 
  excellent 
  survey 
  of 
  the 
  

   genus 
  and 
  of 
  the 
  variation 
  of 
  D. 
  quinquecirrlia, 
  see 
  Mayer 
  (1910). 
  

  

  