﻿94 
  PROCICKDINGS 
  OF 
  THU 
  MALACOLOGICAL 
  SOCIEXr. 
  

  

  margin, 
  both 
  on 
  the 
  inside 
  and 
  the 
  outside, 
  tlie 
  irregularity 
  

   occasionally 
  taking 
  the 
  form 
  of 
  a 
  rude 
  tubercle 
  inside, 
  more 
  or 
  less 
  

   separate 
  from 
  the 
  cusp 
  ; 
  outside, 
  no 
  denticles. 
  

  

  cmgulata, 
  L. 
  : 
  Cape 
  of 
  Good 
  Hope. 
  Central 
  cusp 
  long 
  and 
  thick, 
  

   the 
  root 
  descending 
  to 
  the 
  base, 
  but 
  not 
  projecting 
  through 
  it, 
  side 
  

   cusps 
  short, 
  broad, 
  sharply 
  pointed, 
  conspicuously 
  denticlcd 
  lialf-"way 
  

   up 
  inside 
  ; 
  outside, 
  three 
  well-marked 
  denticles, 
  the 
  inside 
  and 
  largest 
  

   of 
  which 
  is 
  climbing 
  ; 
  knob 
  blunt, 
  prominent. 
  (Fig. 
  12.) 
  

  

  clavigera, 
  Lischke 
  : 
  Japan. 
  Central 
  cusp 
  long, 
  narrow, 
  sharply 
  

   pointed, 
  side 
  cusps 
  rather 
  narrow, 
  sharp, 
  and 
  long, 
  sharply 
  denticled 
  

   about 
  half-way 
  up 
  on 
  inside; 
  outside, 
  4-5 
  sharp 
  prominent 
  denticles, 
  

   two 
  of 
  which 
  climb; 
  knob 
  prominent. 
  (Fig. 
  8.) 
  

  

  Compare 
  this 
  with 
  hronni, 
  Dunk. 
  

  

  coro7iata, 
  Lam.: 
  Guinea 
  coast. 
  Central 
  cusp 
  very 
  long 
  and 
  

   rather 
  thick, 
  side 
  cusps 
  sharp, 
  with 
  a 
  small 
  sharp 
  denticle 
  high 
  up 
  

   on 
  the 
  inside; 
  four 
  prominent 
  toothlets 
  outside, 
  one 
  slightly 
  

   climbing; 
  knob 
  short 
  and 
  blunt. 
  (Fig. 
  11.) 
  

  

  A 
  specimen 
  from 
  Demerara 
  shows 
  a 
  transparent 
  central 
  cusp, 
  no 
  

   denticle 
  on 
  the 
  inside 
  of 
  the 
  side 
  cusps, 
  two 
  deeply 
  cut 
  blunt 
  denticles 
  

   outside 
  ; 
  knob 
  very 
  prominent. 
  

  

  The 
  var. 
  gtiatemalensis, 
  Pils., 
  corresponds 
  to 
  the 
  Guinea 
  form, 
  

   except 
  that 
  the 
  outer 
  denticles 
  are 
  not 
  quite 
  so 
  })rominent, 
  while 
  the 
  

   knob 
  is 
  more 
  conspicuous. 
  These 
  three 
  forms, 
  from 
  different 
  

   localities, 
  sliow 
  conclusively 
  how 
  unstable 
  are 
  the 
  denticles, 
  both 
  

   in 
  number 
  and 
  shape. 
  

  

  deltoidea, 
  Lara. 
  : 
  Barbadoes. 
  Central 
  cusp 
  broadly 
  triangular, 
  

   one-third 
  as 
  long 
  again 
  as 
  the 
  side 
  cusps 
  ; 
  side 
  cusps 
  sharply 
  pointed, 
  

   with 
  a 
  strong 
  blunt 
  denticle 
  low 
  down 
  on 
  the 
  inside 
  ; 
  exterior 
  denticles 
  

   usually 
  absent, 
  onlv 
  faint 
  wrinkles 
  ; 
  knob 
  blunt, 
  not 
  prominent. 
  

   (Fig. 
  3.) 
  

  

  Two 
  other 
  specimens 
  sliow, 
  in 
  one 
  case 
  two, 
  in 
  the 
  other 
  one 
  

   tiny 
  denticle, 
  outside 
  the 
  side 
  cusps. 
  

  

  echinata, 
  Blainv. 
  : 
  AV. 
  Australia. 
  Central 
  cusp 
  thick, 
  very 
  long 
  

   and 
  sharply 
  pointed, 
  2^ 
  times 
  the 
  length 
  of 
  the 
  side 
  cusps, 
  and 
  set 
  

   in 
  a 
  slight 
  depression 
  of 
  the 
  upper 
  margin 
  ; 
  side 
  cusps 
  with 
  a 
  blunt 
  

   denticle, 
  more 
  a 
  hump 
  than 
  a 
  denticle, 
  on 
  the 
  inside 
  ; 
  outside, 
  no 
  

   denticles; 
  knob 
  fairly 
  prominent; 
  base 
  slightly 
  waved. 
  (Fig. 
  5.) 
  

  

  cchinulata, 
  Lara. 
  : 
  Karachi. 
  Central 
  cusp 
  long, 
  regularly 
  

   triangular, 
  not 
  thicker 
  than 
  the 
  side 
  cusps; 
  side 
  cusps 
  about 
  half 
  

   the 
  length 
  of 
  the 
  central, 
  set 
  with 
  a 
  sharp 
  prominent 
  denticle 
  about 
  

   half-way 
  up 
  on 
  the 
  inside 
  ; 
  outside, 
  4-5 
  denticles, 
  one 
  or 
  two 
  

   climbing, 
  very 
  small, 
  the 
  uppermost 
  quite 
  high 
  up, 
  three 
  prominent, 
  

   largest 
  close 
  to 
  the 
  knob; 
  knob 
  prominent. 
  

  

  fasciata, 
  Ileeve 
  : 
  Ascension 
  I. 
  Central 
  cusp 
  long, 
  rather 
  broad; 
  

   side 
  cusps 
  narrower, 
  moderately 
  long, 
  sharp 
  at 
  point, 
  and 
  broadening 
  

   out 
  about 
  half-way 
  down 
  ; 
  a 
  prominent 
  inside 
  denticle, 
  which 
  is 
  

   rather 
  deeply 
  cut; 
  outside, 
  one 
  very 
  small 
  climbing 
  denticle, 
  then 
  

   three 
  well-marked 
  but 
  rather 
  blunt 
  denticles 
  ; 
  knob 
  prominent. 
  

  

  In 
  another 
  specimen 
  (Ascension 
  I.) 
  there 
  are 
  five 
  exterior 
  denticles 
  

   (one 
  climbing) 
  ; 
  216 
  rows 
  in 
  all 
  were 
  counted. 
  

  

  