﻿COOKE: 
  THE 
  KADULA 
  IN 
  THAIS, 
  ETC. 
  97 
  

  

  smithi, 
  Braz. 
  : 
  Lord 
  Howe's 
  I. 
  Central 
  cusp 
  ratlier 
  short, 
  broad, 
  

   one-half 
  to 
  one-third 
  longer 
  than 
  side 
  cusps; 
  side 
  cusps 
  short, 
  rather 
  

   broad, 
  with 
  a 
  strong 
  bluutish 
  denticle 
  scarcely 
  half-way 
  up 
  on 
  tlie 
  

   inside 
  ; 
  outside, 
  three 
  well-marked 
  prominent 
  denticles, 
  one 
  climbing 
  ; 
  

   knob 
  outside, 
  rather 
  small. 
  

  

  succmcta, 
  Mart.; 
  texiiliosa,Jja.m.: 
  W.Australia 
  (Albany, 
  Bunbury), 
  

   Victoria, 
  Tasmania, 
  Sydney, 
  New 
  Zealand. 
  A 
  number 
  of 
  specimens 
  

   labelled 
  as 
  one 
  or 
  other 
  of 
  these 
  species 
  have 
  been 
  examined. 
  I 
  am 
  

   not 
  prepared 
  with 
  any 
  positive 
  statement 
  as 
  to 
  the 
  identity 
  or 
  

   distinctness 
  of 
  the 
  two 
  species, 
  and 
  it 
  is 
  quite 
  possible 
  that 
  specimens 
  

   given 
  to 
  or 
  labelled 
  by 
  Professor 
  Gwatkin 
  as 
  succmcta 
  may 
  be 
  

   textiliosa, 
  or 
  vice 
  versa. 
  But 
  what 
  is 
  certain 
  is 
  this: 
  there 
  are 
  two 
  

   distinct 
  types 
  of 
  rhachidian 
  tooth 
  — 
  (1) 
  cusps 
  all 
  narrow, 
  very 
  sharply 
  

   pointed, 
  and 
  of 
  equal 
  thickness, 
  so 
  that 
  they 
  can 
  all 
  be 
  brought 
  into 
  

   focus 
  at 
  once 
  ; 
  side 
  cusps 
  about 
  two-thirds 
  length 
  of 
  the 
  central 
  ; 
  inside 
  

   denticle 
  on 
  side 
  cusps 
  often 
  freakish, 
  hooked, 
  or 
  broken 
  ; 
  outside, 
  

   6-7 
  small 
  denticles, 
  three 
  climbing 
  higli 
  ; 
  (2) 
  central 
  cusp 
  thick, 
  more 
  

   broadly 
  triangular 
  than 
  the 
  side 
  cusps, 
  and 
  longer 
  in 
  proportion; 
  

   inside 
  denticle 
  not 
  freakish 
  or 
  irregular 
  ; 
  outside, 
  no 
  climbing 
  or 
  

   other 
  denticles, 
  a 
  few 
  obscure 
  wrinkles 
  only. 
  (Figs. 
  17, 
  18.) 
  

  

  The 
  evidence 
  strongly 
  points 
  to 
  (1) 
  being 
  textiliosa 
  and 
  (2) 
  

   siiceincta. 
  

  

  trigona, 
  Reeve: 
  China. 
  Central 
  cusp 
  long, 
  sharp, 
  broad 
  at 
  the 
  

   base, 
  side 
  cusps 
  short 
  and 
  broad, 
  shai'ply 
  deuticled 
  about 
  half-way 
  

   up 
  on 
  the 
  inside 
  ; 
  outside, 
  four 
  strong 
  conspicuous 
  denticles, 
  two 
  of 
  

   which 
  climb 
  high 
  and 
  stand 
  out 
  from 
  the 
  cusp 
  in 
  a 
  remarkable 
  way; 
  

   knob 
  sharp 
  and 
  conspicuous. 
  

  

  ttimulosa, 
  Reeve 
  : 
  Japan. 
  Central 
  cusp 
  long, 
  sharp, 
  not 
  very 
  

   thick, 
  side 
  cusps 
  sharp, 
  narrow 
  at 
  the 
  point, 
  broadening 
  below 
  the 
  

   denticle, 
  which 
  is 
  strong 
  and 
  sharp, 
  set 
  high 
  up 
  on 
  the 
  inside; 
  

   outside, 
  5-6 
  denticles, 
  1-2 
  of 
  which 
  are 
  climbing; 
  knob 
  strong. 
  

  

  Yar. 
  problematica, 
  Baker. 
  Inner 
  denticle 
  very 
  large 
  and 
  prominent, 
  

   six 
  exterior 
  denticles, 
  deeply 
  rooted, 
  one 
  climbing 
  slightly, 
  one 
  quite 
  

   half-way 
  up 
  the 
  cusp. 
  

  

  Haustkum, 
  Perry, 
  and 
  Lepsiella, 
  Iredale. 
  

  

  The 
  characteristic 
  of 
  the 
  radula 
  of 
  the 
  Iiansfnim 
  group 
  is 
  a 
  

   rhachidian 
  tooth 
  on 
  which 
  are 
  set 
  five 
  prominent 
  cusps, 
  of 
  which 
  

   the 
  central 
  is 
  always 
  the 
  largest, 
  and 
  sometimes 
  {lumstrum, 
  lacunosa) 
  

   much 
  the 
  largest. 
  The 
  cusps 
  are 
  more 
  or 
  less 
  equidistant 
  from 
  one 
  

   another, 
  though 
  there 
  is 
  a 
  tendency 
  for 
  the 
  two 
  outer 
  cusps 
  on 
  

   each 
  side 
  to 
  draw 
  together, 
  and 
  away 
  from 
  the 
  central. 
  In 
  shape 
  

   the 
  cusps 
  vary, 
  being 
  (1) 
  all 
  rather 
  sharp 
  and 
  pointed 
  [haiistrum) 
  

   or 
  (2) 
  central 
  cusp 
  pointed, 
  side 
  cusps 
  somewhat 
  blunt 
  (all 
  the 
  rest). 
  

   Instead 
  of 
  being 
  squarely 
  oblong, 
  the 
  mass 
  of 
  the 
  tooth 
  is 
  com- 
  

   pressed 
  above 
  and 
  below, 
  making 
  the 
  tooth 
  narrow 
  in 
  depth, 
  in 
  

   proportion 
  to 
  its 
  width. 
  The 
  knob 
  has 
  varying 
  degrees 
  of 
  prominence. 
  

   The 
  base 
  is 
  usually 
  doubly 
  waved, 
  with 
  a 
  projection 
  in 
  the 
  centre, 
  

   opposite 
  to 
  the 
  central 
  cusp; 
  this 
  projection 
  is 
  most 
  prominent 
  in 
  

   scobina 
  and 
  its 
  varieties. 
  

  

  