﻿ECHINODEKMATA. 
  

  

  155 
  

  

  Antedon. 
  

  

  adeonJB 
  A. 
  r- 
  

  

  b 
  

  

  milberti 
  A. 
  r* 
  

  

  b 
  

  

  pinuiformis 
  -^^ 
  r' 
  

  

  carpenteri 
  A. 
  -■ 
  

  

  puraila 
  A. 
  — 
  

  

  bidens 
  A. 
  -• 
  

  

  a 
  

  

  loveni 
  A. 
  — 
  

  

  X 
  

  

  decipiens 
  A. 
  (3)^ 
  

  

  reginae 
  A. 
  2.(2)r 
  

  

  irregularis 
  A. 
  3.(2)r 
  

  

  olegans 
  A. 
  3. 
  

  

  (2)b_ 
  

   (■■i) 
  c 
  

  

  gyges 
  A. 
  2.2.j^. 
  

  

  briareus* 
  A. 
  3.2.(2)^. 
  

  

  microdiscus 
  A. 
  3.3.(3)-. 
  

  

  ACXINOMETKA. 
  

  

  solaria 
  A'E— 
  — 
  

  

  2 
  a 
  

  

  intermedia 
  A'R- 
  •-• 
  

  

  2 
  a 
  

  

  robusta 
  A'R— 
  . 
  r- 
  

  

  u 
  b 
  

  

  cumingi 
  A 
  -• 
  

  

  coppingeri 
  A'— 
  

  

  ukesi 
  

  

  ,-pd.br 
  

  

  A'R 
  

  

  2 
  

   (ab) 
  

  

  parvicirra 
  A'3.3. 
  — 
  

  

  alternans 
  A'3.2.3.2. 
  

  

  • 
  • 
  A 
  /-nfl.br 
  a 
  

  

  paucicirra 
  A 
  K—^ 
  — 
  

  

  multifida 
  A'3.2.2.-- 
  

  

  a 
  

  

  rA'3.2.-- 
  

  

  a 
  

   variabilis 
  < 
  A'3.3.— 
  

  

  U'3.(2).(2)^. 
  

  

  From 
  the 
  table 
  of 
  Antedon 
  formuloe 
  some 
  facts 
  become 
  at 
  once 
  

   apparent 
  : 
  — 
  

  

  (a) 
  There 
  are 
  six 
  examples 
  among 
  the 
  more 
  than 
  ten-rayed 
  forms 
  

   in 
  which 
  the 
  arms 
  are 
  not 
  a 
  regular 
  multiple 
  of 
  ten 
  — 
  that 
  is, 
  not 
  20, 
  

   40, 
  or 
  80 
  ; 
  this 
  is 
  clear 
  from 
  the 
  sign 
  for 
  the 
  palmar 
  or 
  post-palmar 
  

   being 
  in 
  these 
  cases 
  placed 
  within 
  brackets. 
  

  

  (/3) 
  In 
  aU 
  cases 
  cirri 
  are 
  developed, 
  and 
  these 
  are 
  rarely 
  very 
  

   numerous 
  or 
  very 
  long. 
  

  

  (y) 
  In 
  no 
  case 
  is 
  the 
  radial 
  axillary 
  a 
  syzygy. 
  

  

  A 
  moment's 
  inspection 
  of 
  the 
  table 
  of 
  formulae 
  for 
  the 
  Aciino- 
  

   metrce 
  will 
  reveal 
  to 
  the 
  student 
  a 
  number 
  of 
  interesting 
  facts 
  : 
  — 
  

  

  (a) 
  Three 
  species 
  have 
  the 
  same 
  structural 
  characters, 
  and 
  only 
  

  

  * 
  A 
  study 
  of 
  this 
  species 
  is 
  sufficient 
  to 
  bIiow 
  tlio 
  advantage 
  of 
  Mr. 
  Carpenter's 
  

   proposal 
  to 
  register 
  the 
  number 
  of 
  joints 
  in 
  each 
  division 
  over 
  my 
  proposal 
  to 
  

   register 
  rather 
  the 
  syzygies 
  first 
  of" 
  all, 
  as 
  A. 
  briareus 
  has 
  no 
  syzygies 
  on 
  the 
  

   palmars 
  or 
  succeeding 
  joints 
  where 
  the 
  arms 
  divide 
  again. 
  

  

  