﻿ANATOMY 
  AND 
  AFFINITIES 
  OF 
  THE 
  TI{OCHin.f;. 
  35 
  

  

  under 
  the 
  sub-genus 
  Calliostoma 
  (Swainson), 
  or 
  Zizyphi- 
  

   nus 
  (Leach). 
  According 
  to 
  the 
  latter 
  system 
  we 
  have 
  the 
  

   species 
  Trochus 
  liueatus 
  inchided 
  in 
  a 
  separate 
  sub-genus, 
  

   Trochocochlea 
  (Klein), 
  which 
  species 
  is 
  the 
  only 
  British 
  

   representative 
  of 
  the 
  sub-genus, 
  though 
  there 
  are 
  numerous 
  

   exotic 
  species 
  belonging 
  to 
  it. 
  This 
  separation 
  of 
  T. 
  liuea- 
  

   tus 
  from 
  the 
  sub-genus 
  Gibbula, 
  in 
  whicii 
  it 
  is 
  placed 
  Ijy 
  

   Forbes 
  and 
  Hanley, 
  is 
  based 
  upon 
  conchological 
  grounds 
  

   which 
  to 
  my 
  mind 
  do 
  not 
  seem 
  to 
  be 
  of 
  sufficient 
  importance 
  

   to 
  justify 
  it, 
  though 
  my 
  own 
  observations 
  are 
  based 
  upon 
  the 
  

   examination 
  of 
  a 
  single 
  species, 
  T. 
  lineatus. 
  

  

  The 
  charactei'S 
  of 
  the 
  three 
  sub-genera 
  Gibbula, 
  Trocho- 
  

   cochlea, 
  and 
  Calliostoma 
  are 
  given 
  by 
  Jeffries 
  (24) 
  as 
  

   follows 
  : 
  

  

  1. 
  Gibbula 
  (Leach). 
  — 
  Shell 
  low 
  spired 
  and 
  umbilicate. 
  

  

  Examples 
  : 
  T. 
  magus 
  (PI. 
  4, 
  fig. 
  1). 
  

   T. 
  cinerarius 
  (fig. 
  2). 
  

  

  2. 
  Trochocochlea 
  (Klein). 
  — 
  Spire 
  moderately 
  raised, 
  base 
  

   slightly 
  umbilicate 
  in 
  the 
  adult 
  and 
  perforated 
  in 
  the 
  young, 
  

   pillar 
  lip 
  furnished 
  with 
  a 
  strong 
  tubercular 
  tooth. 
  

  

  Example: 
  T. 
  lineatus 
  (fig. 
  3). 
  

  

  2. 
  Calliostoma 
  (Swainson). 
  — 
  Spire 
  pyramidal, 
  base 
  im- 
  

   perforate, 
  pillar 
  lip 
  notched 
  or 
  angulated 
  at 
  the 
  lower 
  part. 
  

   Example: 
  T. 
  zizyphinus 
  (fig. 
  4). 
  

  

  Apparently 
  the 
  only 
  difference 
  in 
  the 
  characters 
  of 
  the 
  sub- 
  

   genera 
  Trochocochlea 
  and 
  G 
  i 
  b 
  b 
  u 
  1 
  a 
  is 
  in 
  the 
  height 
  of 
  the 
  

   shell, 
  the 
  absence 
  of 
  an 
  umbilcus, 
  and 
  the 
  presence 
  of 
  a 
  tooth 
  

   on 
  the 
  pillar 
  lip. 
  But 
  these 
  characteristics 
  are 
  not 
  necessarily 
  

   confined 
  to 
  the 
  sub-genus 
  Trochocochlea, 
  for 
  species 
  of 
  

   Gibbula 
  may 
  occasionally 
  be 
  imperforate 
  or 
  high 
  spired 
  

   (T, 
  cinerarius, 
  fig. 
  3). 
  As 
  Gwyn 
  Jeffries 
  remai-ks 
  (24, 
  

   vol. 
  iii, 
  p. 
  294), 
  " 
  The 
  shells 
  are 
  usually 
  low 
  spired 
  and 
  deeply 
  

   umbilicate, 
  but 
  varieties 
  of 
  T. 
  tumidus, 
  T. 
  umbilicatus, 
  

   and 
  T. 
  c 
  i 
  n 
  e 
  r 
  a 
  r 
  i 
  u 
  s 
  have 
  the 
  spire 
  raised 
  . 
  Again, 
  T. 
  lineatus 
  

   is 
  the 
  only 
  representative 
  of 
  Klein's 
  genus 
  Trochocochlea, 
  

   in 
  which 
  the 
  spire 
  is 
  raised, 
  the 
  base 
  imperforate, 
  and 
  the 
  

   pdlar 
  lip 
  furnished 
  with 
  a 
  blunt 
  tubercle 
  or 
  notch 
  ; 
  the 
  last 
  

  

  