﻿234 
  

  

  PEOCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  In 
  cornea 
  the 
  base 
  is 
  much 
  broader 
  than 
  in 
  linea, 
  and 
  less 
  deeply 
  

   arched 
  below, 
  while 
  the 
  interruptions 
  of 
  tlie 
  slope 
  of 
  the 
  base, 
  which 
  

   are 
  mere 
  knobs 
  in 
  cornea, 
  are 
  distinct 
  denticles 
  in 
  linea. 
  The 
  lateral 
  

   cusps 
  in 
  li7iea 
  are 
  blunt, 
  and 
  of 
  nearly 
  equal 
  size, 
  in 
  cornea 
  they 
  are 
  

   sharper, 
  the 
  external 
  cusp 
  much 
  the 
  longest. 
  In 
  the 
  rhuchidian 
  of 
  

   cornea 
  there 
  is 
  no 
  sign 
  of 
  the 
  two 
  subsidiary 
  front 
  denticles, 
  making 
  

   five 
  in 
  all, 
  as 
  figured 
  by 
  Troschel. 
  Striata, 
  Hutt., 
  if 
  Huttou's 
  figure 
  

   is 
  correct, 
  is 
  exactly 
  the 
  same 
  type 
  as 
  linea. 
  

  

  Group 
  2. 
  — 
  Rhachidian 
  tooth 
  with 
  eight 
  small 
  denticles, 
  nearly 
  

   equal 
  in 
  size, 
  base 
  broadly 
  oblong, 
  rounded 
  above, 
  arched 
  below, 
  

   sides 
  slightly 
  prolonged 
  into 
  wings; 
  laterals 
  tricuspid, 
  simple, 
  curved, 
  

   inward, 
  the 
  two 
  inner 
  cusps 
  close 
  together, 
  suggesting 
  the 
  sub- 
  

   division 
  of 
  a 
  single 
  cusp. 
  

  

  To 
  this 
  type 
  belongs 
  /er/rrt!, 
  Reeve. 
  

  

  ^•mv-, 
  Aiv 
  \ 
  

  

  

  

  ^ 
  / 
  

  

  

  6 
  

  

  C^ 
  

  

  a<y 
  

  

  U 
  

  

  10 
  

  

  The 
  general 
  form 
  of 
  radula 
  has 
  a 
  close 
  similarity 
  to 
  that 
  of 
  

   Group 
  {b) 
  of 
  the 
  Cape 
  Conmiella 
  {delalandii, 
  Kien., 
  lagenaria, 
  Lam., 
  

   limhosa. 
  Lam., 
  porcata, 
  Gmel.), 
  as 
  described 
  antea, 
  p. 
  229. 
  

  

  Group 
  3. 
  — 
  Rhachidian 
  tooth 
  tricuspid 
  on 
  a 
  simple 
  base, 
  base 
  usually 
  

   rounded 
  at 
  the 
  top, 
  scarcely 
  arched 
  below 
  ; 
  laterals 
  tricuspid, 
  simple, 
  

   the 
  two 
  inner 
  cusps 
  close 
  together, 
  representing 
  a 
  single 
  subdivided 
  

   cusp. 
  

  

  The 
  New 
  Zealand 
  species 
  (1) 
  flavescens, 
  Hutt., 
  (2) 
  littorinoides, 
  

   Reeve, 
  (3) 
  vittata, 
  Quoy, 
  the 
  Tasmanian 
  (4) 
  clarkei, 
  T.-\Voods, 
  and 
  

   the 
  Cape 
  (5) 
  quelcetti, 
  Smith, 
  belong 
  to 
  this 
  type. 
  

  

  The 
  radula 
  of 
  quelcetti, 
  however, 
  with 
  its 
  square 
  base, 
  angled 
  at 
  

   the 
  top 
  and 
  arched 
  below, 
  is 
  scarcely 
  distinguishable 
  from 
  those 
  

  

  