﻿PKOCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  Straparollus, 
  and 
  Tornatella 
  average 
  5 
  species 
  each. 
  The 
  ex- 
  

   tremely 
  rare 
  genera 
  having 
  only 
  one 
  or 
  two 
  representative 
  species 
  

   each 
  are 
  : 
  — 
  Delphinula 
  (D. 
  nuclei, 
  in 
  the 
  Upper 
  Lias, 
  and 
  D. 
  rejlexi- 
  

   labrum 
  in 
  the 
  Lower) 
  ; 
  Eucyclus 
  (E. 
  alpinus, 
  and 
  E. 
  elegans, 
  Lower 
  

   Lias) 
  ; 
  Exelissa 
  (E. 
  numismalis, 
  Middle 
  Lias) 
  ; 
  Hydrobia 
  (E. 
  solidula, 
  

   Lower 
  Lias) 
  ; 
  Monodonta 
  (M. 
  modesta, 
  Middle 
  Lias) 
  ; 
  Nerita 
  (N. 
  

   alternately 
  Lower 
  Lias) 
  ; 
  Proserpina 
  (P. 
  Lyelli, 
  Lower, 
  and 
  P. 
  Hasina, 
  

   Middle 
  Lias); 
  Onustus,Tvith. 
  3 
  species: 
  Pterochilus 
  (P. 
  primus, 
  Lower); 
  

   Pyrula 
  (P. 
  liasica, 
  Lower) 
  ; 
  Tectaria 
  with 
  3 
  species, 
  all 
  Middle 
  ; 
  

   Trochotoma 
  with 
  3 
  species, 
  and 
  Rimula 
  with 
  3 
  species, 
  all 
  Lower 
  

   Lias. 
  Only 
  one 
  of 
  these 
  24 
  species 
  (Onustus 
  pyramidatus) 
  ranges 
  

   higher 
  than 
  the 
  Upper 
  Lias. 
  This, 
  added 
  to 
  the 
  fact 
  that 
  only 
  5 
  other 
  

   species 
  of 
  the 
  largely 
  represented 
  class 
  Gasteropoda, 
  and 
  20 
  Lamelli- 
  

   branehiata, 
  pass 
  to 
  higher 
  beds, 
  shows 
  how 
  restricted 
  is 
  the 
  whole 
  

   Molluscan 
  fauna 
  of 
  the 
  Lias, 
  which 
  now 
  numbers 
  948 
  species 
  ; 
  i. 
  e. 
  

   26 
  out 
  of 
  950 
  in 
  round 
  numbers 
  pass 
  upwards. 
  The 
  forms 
  occurring 
  

   in 
  the 
  Fuller's 
  Earth, 
  Great 
  Oolite, 
  andCornbrash 
  are 
  included 
  among 
  

   the 
  1 
  2 
  in 
  the 
  Inferior 
  Oolite, 
  but 
  range 
  higher. 
  Of 
  the 
  226 
  species 
  

   of 
  Gasteropoda 
  occurring 
  in 
  the 
  Lower 
  Lias, 
  only 
  18 
  pass 
  to 
  the 
  

   Middle, 
  and 
  none 
  to 
  the 
  Upper 
  Lias, 
  leaving 
  208 
  species 
  as 
  the 
  abso- 
  

   lute 
  Gasteropod 
  fauna 
  of 
  the 
  lower 
  division. 
  The 
  occurrences 
  in 
  the 
  

   Middle 
  Lias 
  are 
  136 
  (true 
  contents 
  118) 
  ; 
  but 
  only 
  1 
  species 
  {Turbo 
  

   spinulosus) 
  is 
  common 
  to 
  this 
  and 
  the 
  Upper 
  Lias, 
  out 
  of 
  the 
  136 
  (or 
  

   118) 
  species. 
  This 
  analysis 
  shows 
  the 
  value 
  and 
  significance 
  of 
  the 
  

   three 
  divisions, 
  and 
  tho 
  importance, 
  both 
  stratigraphically 
  and 
  

   palaBontologically, 
  of 
  the 
  tripartite 
  arrangement. 
  

  

  Geographically, 
  or 
  in 
  space, 
  the 
  Gasteropoda 
  are 
  intermittently 
  

   distributed 
  through 
  England, 
  the 
  greatest 
  known 
  development 
  being 
  

   in 
  Yorkshire 
  and 
  Warwickshire. 
  I 
  know 
  of 
  no 
  species 
  occurring 
  in 
  

   the 
  zone 
  of 
  JEyoceras 
  planorbls 
  in 
  England. 
  In 
  Yorkshire 
  Messrs. 
  

   Tate 
  and 
  Blake 
  have 
  recorded 
  14 
  genera 
  and 
  26 
  species 
  from 
  the 
  

   Angulatus-beds 
  of 
  Redcar 
  ; 
  and 
  Mr. 
  Tate 
  from 
  the 
  same 
  zone, 
  in 
  five 
  

   localities, 
  Ireland, 
  Marton, 
  Cheltenham, 
  Brocastle, 
  and 
  Sutton, 
  cites 
  

   21 
  genera 
  and 
  39 
  species. 
  M. 
  Martin 
  and 
  M. 
  Collenot, 
  the 
  former 
  

   in 
  his 
  ' 
  Pal. 
  Strat. 
  de 
  l'infra-Lias 
  du 
  Dept. 
  de 
  Cote 
  d'or,' 
  and 
  the 
  

   latter 
  in 
  his 
  ' 
  Description 
  Geologique 
  de 
  l'Auxois,' 
  catalogue 
  no 
  less 
  

   than 
  46 
  species 
  from 
  the 
  zone 
  of 
  JEJyoceras 
  anyulatum. 
  28 
  species 
  are 
  

   recorded 
  by 
  Tate 
  and 
  Blake 
  from 
  the 
  Arietites- 
  BucMandi 
  beds 
  of 
  

   Yorkshire. 
  The 
  zone 
  of 
  Amaltheus 
  oxynotus, 
  standing 
  between 
  the 
  

   rich 
  Bucklandi- 
  and 
  Jamesoni-beds, 
  contains 
  few 
  species 
  — 
  only 
  5 
  or 
  6 
  

   genera 
  and 
  as 
  many 
  species. 
  Nowhere 
  in 
  Europe 
  is 
  this 
  zone 
  rich 
  

   in 
  organic 
  remains 
  ; 
  and 
  this 
  is 
  equally 
  the 
  case 
  with 
  the 
  beds 
  with 
  

   Arietites 
  raricostatus. 
  Erom 
  the 
  famous 
  Eenny 
  Compton 
  section 
  in 
  

   Warwickshire, 
  and 
  from 
  the 
  zone 
  of 
  JEgoceras 
  Jamesoni, 
  Mr. 
  Beesley 
  

   has 
  obtained 
  30 
  species 
  of 
  Gasteropoda, 
  representing 
  12 
  genera*. 
  Mr. 
  

   Tawney 
  and 
  Mr. 
  Tate 
  also 
  record 
  18 
  species 
  from 
  the 
  same 
  zone 
  at 
  

   Munger, 
  near 
  Eadstock 
  ; 
  and 
  Mr. 
  Tate, 
  in 
  his 
  paper 
  " 
  On 
  the 
  Palse- 
  

  

  * 
  Mr. 
  Beesley 
  has 
  collected 
  200 
  species 
  from 
  this 
  horizon 
  at 
  Fenny 
  

   Compton. 
  

  

  