﻿On 
  the 
  Genera 
  of 
  Recent 
  Clypeastruids. 
  503 
  

  

  This 
  Hue 
  mole-rat, 
  which 
  I 
  have 
  named 
  in 
  honour 
  of 
  its 
  

   discoverer, 
  is 
  no 
  doubt 
  nearly 
  allied 
  to 
  G. 
  ochraceo-cinereus, 
  

   Heugl., 
  with 
  which 
  it 
  shares 
  its 
  chief 
  cranial 
  characteristics. 
  

   But 
  its 
  colour 
  is 
  of 
  the 
  slaty 
  grey 
  found 
  in 
  G. 
  lechei, 
  and 
  

   quite 
  unlike 
  the 
  sandy 
  or 
  ochraceous 
  of 
  Heuglin's 
  species. 
  

  

  LXIX. 
  — 
  The 
  Genera 
  of 
  Recent 
  Clypeastroids. 
  By 
  Hubert 
  

   Lyman 
  Clark, 
  Museum 
  of 
  Comparative 
  Zoology, 
  Cam- 
  

   bridge, 
  U.S.A. 
  

  

  Although 
  the 
  classification 
  of 
  the 
  sea-urchins 
  commonly 
  

   called 
  cake-urchins, 
  sand-dollars, 
  and 
  keyhole-urchins 
  has 
  

   engaged 
  the 
  attention 
  of 
  many 
  zoologists, 
  some 
  of 
  whom 
  

   have 
  held 
  very 
  high 
  rank, 
  the 
  nomenclature 
  in 
  use 
  at 
  the 
  

   present 
  day 
  is 
  very 
  unsatisfactory. 
  That 
  which 
  is 
  used 
  by 
  

   palaeontologists 
  differs 
  from 
  that 
  of 
  their 
  brethren 
  who 
  

   confine 
  their 
  work 
  to 
  Recent 
  forms, 
  and 
  such 
  a 
  name 
  as 
  

   Echiuanthus, 
  for 
  example, 
  means 
  something 
  quite 
  different 
  

   in 
  one 
  field 
  from 
  what 
  it 
  does 
  in 
  the 
  other. 
  The 
  difficulties 
  

   seem 
  to 
  arise 
  chiefly 
  from 
  the 
  fact 
  that 
  leading 
  echiuologists, 
  

   such 
  as 
  the 
  two 
  Agassizs, 
  Duncan, 
  and 
  Lambert, 
  have 
  re- 
  

   fused 
  to 
  accept 
  the 
  tenth 
  edition 
  of 
  the 
  ' 
  Systema 
  Naturae 
  ' 
  

   as 
  the 
  starting-point 
  in 
  nomenclature, 
  but 
  have 
  dated 
  both 
  

   genera 
  and 
  species 
  from 
  pre-Linnean 
  writers. 
  Other 
  articles 
  

   of 
  our 
  present 
  International 
  Code 
  of 
  Nomenclature 
  have 
  also 
  

   been 
  consciously 
  or 
  unconsciously 
  violated, 
  and 
  thus 
  the 
  

   confusion 
  has 
  been 
  made 
  worse. 
  

  

  Having 
  had 
  occasion 
  recently 
  to 
  outline 
  for 
  my 
  own 
  use 
  a 
  

   consistent 
  and 
  satisfactory 
  classification 
  of 
  the 
  Recent 
  Clype- 
  

   astroida, 
  I 
  have 
  found 
  that 
  the 
  application 
  of 
  the 
  Inter- 
  

   national 
  Code 
  results 
  in 
  some 
  important 
  changes 
  ; 
  and 
  as 
  I 
  

   believe 
  these 
  changes 
  are 
  bound 
  to 
  be 
  made 
  ultimately, 
  they 
  

   had 
  better 
  be 
  suggested 
  at 
  once. 
  Fortunately 
  few 
  familiar 
  

   names 
  are 
  altered, 
  and 
  none 
  of 
  these 
  is 
  likely 
  to 
  cause 
  any 
  

   confusion. 
  Of 
  course, 
  those 
  who 
  persist 
  in 
  the 
  maintenance 
  

   of 
  pre-Linnean 
  names 
  cannot 
  accept 
  my 
  conclusions, 
  and 
  I 
  

   shall 
  not 
  expect 
  it 
  ; 
  but 
  I 
  do 
  hope 
  that 
  those 
  who 
  wish 
  to 
  

   obtain 
  a 
  reasonable 
  stability 
  of 
  nomenclature 
  through 
  the 
  

   general 
  acceptance 
  of 
  the 
  International 
  Code 
  will 
  find 
  them- 
  

   selves 
  able 
  to 
  accept 
  the 
  types 
  here 
  given 
  for 
  the 
  different 
  

   genera, 
  even 
  if 
  their 
  own 
  methods 
  or 
  preferences 
  would 
  

   have 
  led 
  them 
  to 
  different 
  results. 
  I 
  hope 
  it 
  is 
  needless 
  

   to 
  add 
  that 
  if 
  I 
  err 
  in 
  the 
  application 
  of 
  the 
  code 
  or 
  in 
  the 
  

  

  