﻿228 
  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETY. 
  

  

  nearlj' 
  equal 
  in 
  length, 
  set 
  closely 
  together 
  on 
  a 
  base 
  shaped 
  like 
  

   a 
  truncated 
  horse-shoe, 
  cusps 
  simple 
  ; 
  laterals 
  bicuspid 
  on 
  a 
  simple 
  

   base, 
  cusps 
  large, 
  slightly 
  curved, 
  never 
  denticulate. 
  

   I 
  have 
  counted 
  in 
  

  

  adelaidensis^ 
  91 
  + 
  rows 
  of 
  teeth. 
  Imeolata 
  123 
  rows 
  of 
  teeth. 
  

   alveolata 
  113 
  ,, 
  liirida, 
  104 
  ,, 
  

  

  costata 
  107 
  ,, 
  maailata 
  109 
  ,, 
  

  

  filicea 
  112 
  ,, 
  maculosa 
  115 
  ,, 
  

  

  huttoni 
  98+ 
  ,, 
  virgata 
  97+ 
  ,, 
  

  

  Special 
  characterisiics 
  of 
  tke 
  rhachidian 
  tooth 
  in 
  the 
  various 
  

  

  SPECIES. 
  

  

  1. 
  adelaidensis. 
  — 
  Cusps 
  rather 
  narrow 
  and 
  close 
  together. 
  The 
  

   lines 
  of 
  tlie 
  base 
  are 
  somewhat 
  square, 
  and 
  the 
  two 
  lower 
  prolongations 
  

   (hereafter 
  called 
  the 
  wings) 
  of 
  the 
  base 
  are 
  thickly 
  rounded. 
  

  

  2. 
  alveolata. 
  — 
  Cusps 
  rather 
  short, 
  further 
  apart 
  than 
  in 
  adelatdetisis, 
  

   base-lines 
  not 
  quite 
  so 
  square, 
  wings 
  short, 
  rounded 
  at 
  the 
  ends. 
  

  

  3. 
  codata.- 
  — 
  Cusps 
  small, 
  narrow, 
  very 
  close 
  together, 
  wings 
  of 
  

   the 
  base 
  greatly 
  prolonged, 
  narrowed 
  at 
  their 
  lower 
  ends, 
  lines 
  of 
  the 
  

   base 
  rounded, 
  not 
  squared. 
  

  

  4. 
  filicea. 
  — 
  Cusps 
  short, 
  somewhat 
  elevated 
  above 
  the 
  upper 
  base- 
  

   line, 
  wings 
  of 
  the 
  base 
  prolonged 
  a 
  little, 
  but 
  not 
  nearly 
  so 
  much 
  as 
  

   in 
  costata, 
  angles 
  of 
  base-lines 
  rounded. 
  

  

  5. 
  huttoni.' 
  — 
  There 
  is 
  scarcely 
  any 
  recognizable 
  difference 
  between 
  

   til 
  is 
  species 
  and 
  lineolaia. 
  

  

  6. 
  lineolata. 
  — 
  Closely 
  corresponds 
  to 
  alveolata 
  both 
  in 
  the 
  form 
  of 
  

   cusps 
  and 
  shape 
  of 
  base. 
  

  

  7. 
  liirida.^ 
  — 
  Cusps 
  short, 
  equal 
  in 
  length, 
  rather 
  close 
  togetlier, 
  

   wings 
  of 
  base 
  decidedly 
  prolonged, 
  but 
  not 
  so 
  much 
  as 
  in 
  costata. 
  

  

  8. 
  maculata.- 
  — 
  Cusps 
  prominent, 
  close 
  together, 
  base 
  rounded 
  above, 
  

   wings 
  short 
  and 
  rounded. 
  

  

  9. 
  maculosa. 
  — 
  Cusps 
  markedly 
  triangular 
  in 
  shape, 
  well 
  apart 
  from 
  

   one 
  another, 
  base 
  as 
  in 
  maculata. 
  

  

  10. 
  virgata. 
  — 
  Cusps 
  sharp 
  and 
  small, 
  separate 
  from 
  one 
  another, 
  

   base 
  not 
  prolonged 
  into 
  wings, 
  rather 
  angulate 
  above. 
  

  

  The 
  species 
  of 
  the 
  whole 
  group 
  lie 
  remarkably 
  close 
  together, 
  and 
  

   the 
  one 
  markedly 
  characteristic 
  difference 
  is 
  the 
  prolongation 
  of 
  the 
  

   wings 
  in 
  costata, 
  filicea, 
  and 
  lurida. 
  The 
  shape 
  of 
  the 
  laterals 
  is 
  

   constant, 
  and 
  exhibits 
  scarcely 
  any 
  appreciable 
  difference 
  in 
  the 
  

   various 
  species. 
  

  

  ^ 
  " 
  + 
  " 
  means 
  that 
  a 
  few 
  rows 
  at 
  one 
  or 
  other 
  end 
  of 
  the 
  specimen 
  were 
  missing. 
  

  

  2 
  T. 
  Iredale 
  has 
  pointed 
  out 
  (Trans. 
  N.Z. 
  Inst., 
  xlvii, 
  1914, 
  p. 
  465) 
  that 
  

   by 
  the 
  laws 
  of 
  nomenclature 
  the 
  name 
  eburnea, 
  Eeeve, 
  must 
  displace 
  

   costata, 
  Quoy, 
  quoijana, 
  A. 
  Ad., 
  that 
  of 
  huttoni, 
  Kob, 
  and 
  adspersa, 
  Brug., 
  

   that 
  of 
  maculata. 
  Mart. 
  These 
  names 
  are 
  accordingly 
  adopted 
  in 
  the 
  

   explanation 
  of 
  the 
  figures. 
  

  

  * 
  The 
  dentition 
  of 
  lurida 
  has 
  been 
  figured 
  by 
  Hutton, 
  Trans. 
  N.Z. 
  Inst., 
  

   xiv, 
  1882, 
  p. 
  162, 
  pi. 
  vi 
  ; 
  that 
  of 
  maculata, 
  maculosa, 
  and 
  virgata, 
  ibid., 
  

   XV, 
  1883, 
  p. 
  120, 
  pi. 
  xiii. 
  

  

  