﻿MOLLUSCA. 
  61 
  

  

  The 
  L. 
  Jcevls 
  of 
  Reeve 
  is 
  also 
  L. 
  viaiir'itiana, 
  and 
  quite 
  distinct 
  from 
  

   the 
  L. 
  Icevis 
  of 
  Philippi 
  (?. 
  c. 
  vol. 
  iii. 
  p. 
  10, 
  pi, 
  6. 
  fig. 
  6), 
  which 
  is 
  

   also 
  from 
  the 
  Mauritius. 
  L. 
  unduJata 
  of 
  Gray 
  is 
  also 
  considered 
  a 
  

   variety 
  of 
  L. 
  mauritiana 
  by 
  Mr. 
  Tenison-Woods 
  (l. 
  c. 
  p. 
  72) 
  ; 
  but 
  

   here 
  I 
  think 
  he 
  overstrains 
  the 
  power 
  of 
  variation. 
  Besides 
  the 
  

   difference 
  in 
  form 
  and 
  colour, 
  the 
  violet 
  columella 
  and 
  sculpture 
  

   readily 
  distinguish 
  that 
  shell. 
  In 
  adopting 
  the 
  Lamarckian 
  name 
  

   L. 
  ccfndescens, 
  even 
  supposing 
  the 
  Mediterranean 
  and 
  Australian 
  

   shells 
  were 
  the 
  same 
  species, 
  I 
  think 
  Mr. 
  Tenison-Woods 
  is 
  wrong, 
  

   considering 
  what 
  is 
  said 
  upon 
  this 
  point 
  by 
  Philippi 
  (op. 
  cit. 
  vol. 
  ii. 
  

   p. 
  166), 
  Hanley 
  ('Ipsa 
  Linnsei 
  Conchylia,' 
  p. 
  326), 
  Jeffreys, 
  and 
  

   others. 
  

  

  63. 
  Risella 
  lutea. 
  

  

  Trochus 
  luteus, 
  Quo)/ 
  Sf 
  Gaimard, 
  Voij. 
  ^Astrolabe,'' 
  vol. 
  iii. 
  p. 
  271, 
  

   pi. 
  62. 
  figs. 
  8-11 
  ; 
  'Kiener, 
  Coq. 
  Viv. 
  pi. 
  38. 
  fig. 
  2. 
  

  

  Trochus 
  cicatricosus, 
  Jonas, 
  rhilipprs 
  Ahbild. 
  pi. 
  2. 
  fig. 
  2. 
  

  

  Bembiciiim 
  hiteum, 
  Philippi, 
  Zeitsch. 
  Mnl. 
  1846, 
  p. 
  132. 
  

  

  Risella 
  lutea, 
  Philippi, 
  Kiider's 
  Con.-Cah. 
  p. 
  4, 
  pi. 
  1. 
  figs. 
  ], 
  2. 
  

  

  Risella 
  kielmannseggi, 
  Zelehor, 
  J^erhandl. 
  zool.-botan. 
  Gesellsch. 
  Wien, 
  

   1866, 
  vol. 
  xvi. 
  p. 
  913 
  ; 
  Voy. 
  ' 
  Novara,' 
  pi. 
  xi. 
  figs. 
  11 
  a-d. 
  

  

  Hah. 
  Port 
  Jackson, 
  Port 
  Denison, 
  Port 
  Curtis, 
  and 
  Port 
  Molle 
  

   (Coppinger). 
  

  

  This 
  genus 
  has 
  been 
  suppressed 
  by 
  Mr. 
  Tenison-Woods 
  (Proc. 
  

   Linn. 
  Soc. 
  N. 
  S. 
  Wales, 
  1879, 
  vol. 
  iii. 
  p. 
  61); 
  but, 
  in 
  my 
  judgment, 
  

   it 
  may 
  be 
  retained 
  with 
  advantage 
  as 
  distinct 
  from 
  Littorina. 
  The 
  

   Trochoid 
  form 
  and 
  flattened 
  base 
  of 
  the 
  species 
  is 
  not 
  approached 
  in 
  

   that 
  genus, 
  and 
  the 
  character 
  of 
  the 
  columella 
  is 
  very 
  different. 
  

  

  According 
  to 
  Mr. 
  Tenison-Woods 
  there 
  is 
  but 
  one 
  species 
  ot 
  Risella 
  

   in 
  Australia 
  (H. 
  melanostoma 
  of 
  Gmelin), 
  under 
  which 
  name 
  he 
  

   includes 
  fifteen 
  varieties 
  or 
  species, 
  which 
  have 
  been 
  named 
  and 
  

   described 
  by 
  Lamarck, 
  Quoy, 
  Gray, 
  Philippi, 
  and 
  others. 
  

  

  Although 
  the 
  separation 
  of 
  many 
  species 
  or 
  constant 
  local 
  forms 
  

   seems 
  impossible, 
  we 
  must 
  not 
  therefore 
  ignore 
  their 
  existence. 
  

   Riaella 
  bruni 
  is 
  a 
  South-Australian 
  shell, 
  and 
  does 
  not 
  attain 
  any 
  

   thing 
  like 
  the 
  size 
  of 
  several 
  of 
  the 
  other 
  species, 
  e. 
  g. 
  R. 
  nana, 
  

   R. 
  mdanostoma, 
  and 
  R. 
  imhricata. 
  Although 
  it 
  might 
  be 
  possible 
  

   to 
  get 
  together 
  an 
  immense 
  series 
  of 
  specimens 
  which 
  would 
  unite 
  

   step 
  by 
  step 
  the 
  two 
  most 
  extreme 
  forms, 
  nevertheless 
  the 
  R. 
  hruni 
  

   would 
  still 
  remain 
  the 
  small 
  species 
  from 
  South 
  Australia, 
  and 
  the 
  

   other, 
  the 
  R. 
  imhricata 
  from 
  Sydney, 
  Port 
  Stephens, 
  &c., 
  would 
  also 
  

   be 
  recognizable 
  as 
  such. 
  

  

  I 
  am 
  far 
  from 
  admitting 
  the 
  validity 
  of 
  all 
  the 
  described 
  species 
  ; 
  

   but 
  there 
  are 
  some, 
  I 
  think, 
  which 
  may 
  be 
  retained, 
  at 
  all 
  events, 
  

   with 
  conv.'nience. 
  It 
  is 
  not 
  my 
  intention 
  now 
  to 
  discuss 
  this 
  subject 
  

   further, 
  but, 
  in 
  conclusion, 
  will 
  call 
  attention 
  to 
  Philippi's 
  mono- 
  

   graph 
  of 
  the 
  genus, 
  w^hich 
  has 
  been 
  altogether 
  overlooked 
  by 
  Crosse 
  

   (Journ. 
  de 
  Conch. 
  1864) 
  aud 
  by 
  Tenison-Woods 
  ; 
  it 
  was 
  published 
  

   in 
  1853 
  in 
  Kiister's 
  ' 
  Conchylien-Cabinet,' 
  and 
  contains 
  the 
  following 
  

  

  