﻿44 
  

  

  A 
  FURTHER 
  Js^OTE 
  ON 
  THE 
  ANATOMICAL 
  DIFFERENCES 
  

   BETWEEN 
  THE 
  GENERA 
  CYPR^JA 
  AND 
  TRIVIA. 
  

  

  Ey 
  H. 
  0. 
  W. 
  Shaw, 
  F.Z.S. 
  

  

  Read 
  \Qth 
  December, 
  1909. 
  

  

  Since 
  writing 
  my 
  last 
  paper 
  on 
  Cyprcea 
  and 
  Trivia,^ 
  in 
  which 
  

   I 
  endeavoured 
  to 
  show 
  the 
  anatomical 
  differences 
  which 
  I 
  considered 
  

   sufficient 
  to 
  establish 
  Trivia 
  as 
  a 
  genus, 
  Professor 
  W. 
  H. 
  Dall, 
  to 
  

   whom 
  I 
  am 
  much 
  obliged 
  for 
  his 
  information, 
  has 
  kindly 
  drawn 
  my 
  

   attention 
  to 
  a 
  further 
  distinction, 
  which 
  I 
  have 
  not 
  noticed 
  in 
  the 
  

   previous 
  paper. 
  I 
  may 
  mention 
  that 
  the 
  following 
  observations 
  are 
  

   taken 
  from 
  literature 
  only, 
  as 
  I 
  have 
  not 
  had 
  the 
  opportunity 
  of 
  

   examining 
  any 
  live 
  specimens. 
  My 
  thanks 
  are 
  due 
  to 
  Mr. 
  E. 
  A. 
  Smith, 
  

   who, 
  with 
  his 
  usual 
  kindness, 
  has 
  enabled 
  me 
  to 
  verify 
  certain 
  

   references. 
  

  

  In 
  Trivia 
  Enropma 
  {ardica), 
  as 
  described 
  by 
  Clark 
  : 
  ' 
  " 
  The 
  head 
  is 
  

   scarcely 
  a 
  projection, 
  concave 
  laterally, 
  flat 
  above, 
  and 
  from 
  its 
  central 
  

   basal 
  vertical 
  fissure 
  a 
  long 
  proboscis 
  can 
  be 
  exserted, 
  though 
  it 
  is 
  

   rarely 
  seen." 
  The 
  animal 
  of 
  Trivia 
  Eiiropaa 
  (arctica) 
  is 
  figured 
  by 
  

   Forbes 
  & 
  Hanley 
  in 
  their 
  History 
  of 
  British 
  MoUusca, 
  1853, 
  vol. 
  i, 
  

   pi. 
  NN, 
  figs. 
  0-7, 
  fig. 
  7 
  showing 
  the 
  under 
  surface 
  of 
  head 
  ; 
  and 
  the 
  

   description 
  rims, 
  op. 
  cit., 
  vol. 
  iii, 
  p. 
  494, 
  "head 
  broad, 
  sublunate 
  ; 
  

   proboscis 
  retractile." 
  H. 
  & 
  A. 
  Adams, 
  in 
  The 
  Genera 
  of 
  Recent 
  

   Iloll'usca, 
  vol. 
  iii, 
  ^\. 
  xxviii, 
  fig. 
  5, 
  have 
  copied 
  Forbes 
  & 
  Hanley's 
  

   fig. 
  5. 
  

  

  Cyprcca 
  has, 
  according 
  to 
  Messrs. 
  Adams, 
  op. 
  cit., 
  vol. 
  i, 
  p. 
  264, 
  

   " 
  head 
  broad, 
  rostrum 
  short." 
  Troschel, 
  in 
  his 
  Bas 
  Geliss 
  der 
  

   Schnecken, 
  vol. 
  i, 
  pi. 
  xvii, 
  fig. 
  4, 
  gives 
  a 
  figure 
  of 
  the 
  liead 
  of 
  Cyprcea 
  

   carneola, 
  and 
  on 
  pp. 
  202 
  and 
  203 
  op. 
  cit. 
  he 
  differentiates 
  at 
  length 
  

   lietween 
  Cyprcca 
  and 
  Trivia. 
  From 
  his 
  remarks 
  and 
  the 
  other 
  works 
  

   consulted, 
  as 
  Professor 
  Dall 
  observes 
  in 
  his 
  communication 
  to 
  me, 
  it 
  

   appears 
  that 
  Cyprcea 
  lias 
  a 
  short, 
  stout, 
  subtruncate 
  muzzle, 
  from 
  

   which 
  a 
  short 
  evertible 
  proboscis 
  maj^ 
  be 
  exserted, 
  whereas 
  Trivia 
  has 
  

   no 
  muzzle, 
  but 
  a 
  long 
  slender 
  proboscis, 
  which, 
  when 
  withdrawn, 
  

   leaves 
  onlj- 
  a 
  vertical 
  slit 
  between 
  the 
  tentacles 
  on 
  the 
  lower 
  side 
  of 
  

   the 
  head 
  (see 
  Forbes 
  & 
  Hanley, 
  op. 
  cit., 
  fig. 
  7). 
  I 
  am 
  informed 
  by 
  

   Professor 
  Dall 
  that 
  Trivia 
  Californiana 
  is 
  very 
  similar 
  to 
  T. 
  arelica. 
  

   The 
  above 
  differences 
  are 
  further 
  proof 
  of 
  the 
  advisability 
  of 
  considering 
  

   'Trivia 
  as 
  a 
  genus 
  ; 
  in 
  fact, 
  Troschel 
  went 
  so 
  far 
  as 
  to 
  establish 
  

   a 
  family 
  Triviacea. 
  

  

  1 
  Proc. 
  Make. 
  Soc, 
  vol. 
  viii, 
  pp. 
  288-313. 
  

  

  - 
  A 
  Hifitory 
  of 
  the 
  British 
  Marine 
  Testaceous 
  Molhisca, 
  1855, 
  p. 
  505. 
  

  

  