﻿G04 
  Mr. 
  U. 
  L. 
  Clark 
  on 
  the 
  

  

  wanting; 
  abactinal 
  end 
  of 
  each 
  interambu- 
  

   lacrum 
  consists 
  of 
  a 
  single 
  large 
  plate 
  adjoining 
  

   genital; 
  test 
  not 
  usually 
  discoidal 
  and 
  never 
  

   with 
  marginal 
  slits 
  or 
  lunules. 
  

   Petals 
  more 
  or 
  less 
  perfect 
  ; 
  madreporic 
  pores 
  

   numerous; 
  size 
  moderate 
  to 
  large, 
  15 
  mm. 
  

   and 
  up 
  in 
  length, 
  (Laganidje.) 
  

  

  Genital 
  pores 
  present 
  in 
  all 
  interradii 
  Lagandm. 
  

  

  Genital 
  pore 
  wanting 
  in 
  posterior 
  interradius. 
  . 
  Peromelia. 
  

   Petals 
  reduced 
  and 
  often 
  rudimentary 
  ; 
  only 
  one 
  

   madreporic 
  pore 
  ; 
  size 
  small, 
  rarely 
  up 
  to 
  

   15 
  mm. 
  in 
  length. 
  (Fibulariid^e.) 
  

   Test 
  more 
  or 
  less 
  elevated, 
  without 
  internal 
  

  

  radiating 
  walls, 
  except 
  usually 
  posteriorly. 
  Fibular 
  ia. 
  

   Test 
  more 
  or 
  less 
  flattened, 
  with 
  internal 
  

  

  radiating 
  walls 
  bounding 
  the 
  ambulacra 
  . 
  . 
  Echinocyamus. 
  

   Actinal 
  ambulacral 
  furrows 
  distinct, 
  at 
  least 
  the 
  

   posterior, 
  and 
  usually 
  all, 
  extending 
  to 
  ambitus 
  ; 
  

   abactinal 
  end 
  of 
  interambulacrum 
  with 
  the 
  

   usual 
  pair 
  of 
  small 
  plates 
  adjoining 
  genital 
  ; 
  

   test 
  commonly 
  more 
  or 
  less 
  discoidal, 
  often 
  

   with 
  marginal 
  slits 
  or 
  lunules. 
  (Scutellid^e.) 
  

   Test 
  without 
  marginal 
  slits 
  or 
  lunules. 
  

  

  Actinal 
  ambulacral 
  furrows 
  unbranched 
  ; 
  

   genital 
  pores 
  5 
  ; 
  abactinal 
  system 
  very 
  

  

  small 
  Alexandria. 
  

  

  Actinal 
  ambulacral 
  furrows 
  more 
  or 
  less 
  forked 
  

   or 
  branched 
  ; 
  genital 
  pores 
  4. 
  

   Petals 
  more 
  or 
  less 
  nearly 
  closed 
  distally 
  . 
  . 
  Scutella. 
  

   Petals 
  broadly 
  open 
  distally. 
  

   Abactinal 
  system 
  at 
  apex 
  of 
  test 
  ; 
  anus 
  

  

  marginal 
  ; 
  petals 
  subequal 
  Echinarachnius. 
  

  

  Abactinal 
  system 
  posterior 
  to 
  apex 
  of 
  test 
  ; 
  

   anus 
  on 
  actinal 
  surface 
  ; 
  posterior 
  

   petals 
  much 
  shorter 
  than 
  others 
  .... 
  Dendraster. 
  

   Test 
  with 
  marginal 
  slits 
  or 
  lunules 
  or 
  both. 
  

  

  Not 
  more 
  than 
  two 
  marginal 
  slits, 
  and 
  often 
  

   none, 
  in 
  posterior 
  half 
  of 
  test-margin. 
  

   No 
  lunule 
  in 
  posterior 
  interambulacrum. 
  

   Two 
  lunules 
  or 
  marginal 
  slits 
  present, 
  one 
  

  

  in 
  each 
  posterior 
  ambulacrum 
  Eehinodiseus. 
  

  

  Five 
  lunules 
  present, 
  one 
  in 
  each 
  ambu- 
  

   lacrum 
  Astriclypeus. 
  

  

  A 
  lunule 
  in 
  posterior 
  interambulacrum. 
  

  

  Genital 
  pores 
  5 
  Eucope. 
  

  

  Genital 
  pores 
  4 
  Mellita. 
  

  

  More 
  than 
  eight 
  marginal 
  slits 
  in 
  posterior 
  

  

  half 
  of 
  test-margin 
  Rotula. 
  

  

  A 
  list 
  of 
  these 
  genera, 
  with 
  their 
  types 
  and 
  other 
  important 
  

   data, 
  follows 
  : 
  — 
  

  

  Anomolanthus, 
  Bell, 
  1884. 
  Proc. 
  Zool. 
  Soc. 
  London, 
  p. 
  43. 
  Type, 
  

   Echinantlms 
  tumidus, 
  Tenison- 
  Woods, 
  1878, 
  Proc. 
  Linn. 
  Soc. 
  

   N.S.W. 
  ii. 
  p. 
  169. 
  Monotypic. 
  

  

  Cjl/ypeaster, 
  Lamarck, 
  1801. 
  Syst. 
  Anim. 
  s. 
  Vert. 
  p. 
  349. 
  Type, 
  

   Echinus 
  rosaceus, 
  Linne, 
  1758, 
  Syst. 
  Nat. 
  ed. 
  10, 
  p. 
  665, 
  = 
  Ec/iia- 
  

   anthus 
  rosaceus 
  of 
  Gray, 
  1825, 
  A. 
  Agassiz, 
  1872, 
  et 
  al. 
  Type 
  

   fixed 
  by 
  elimination 
  by 
  Lamarck, 
  1810, 
  Anim. 
  s. 
  Vert. 
  iii. 
  p. 
  13. 
  

  

  