﻿1 
  68 
  PKOCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  the 
  occurrences 
  in 
  the 
  10 
  horizons 
  number 
  208. 
  They 
  are 
  thus 
  

  

  distributed 
  : 
  — 
  

  

  Species. 
  

  

  Inferior 
  Oolite 
  42 
  

  

  Fullers' 
  Earth 
  5 
  

  

  Great 
  Oolite 
  7 
  

  

  Forest 
  Marble 
  2 
  

  

  Cornbrash 
  3 
  

  

  Kellaways 
  Eock 
  41 
  

  

  Oxford 
  Clay 
  • 
  • 
  45 
  

  

  Coralline 
  Oolite 
  21 
  

  

  Kimmeridge 
  Clay 
  31 
  

  

  Portland 
  Oolite 
  11 
  

  

  208 
  

  

  The 
  same 
  restricted 
  range 
  of 
  species 
  that 
  occurs 
  in 
  the 
  Lias 
  is 
  equally 
  

   marked 
  between 
  the 
  Iuferior 
  Oolite 
  and 
  the 
  immediately 
  succeeding 
  

   rocks. 
  Only 
  one 
  species 
  (Am. 
  fuscus) 
  passes 
  to 
  the 
  Fullers' 
  Earth, 
  

   none 
  to 
  higher 
  beds. 
  In 
  stratigraphical 
  geology 
  the 
  Ammonitidae 
  are 
  

   of 
  the 
  highest 
  importance 
  ; 
  and 
  their 
  value 
  for 
  the 
  purposes 
  of 
  corre- 
  

   lation 
  over 
  distant 
  and 
  extended 
  areas 
  is 
  admitted 
  by 
  all 
  competent 
  

   observers. 
  

  

  The 
  families 
  ^Egoceratidae 
  and 
  Arcestidae 
  range 
  through 
  the 
  

   8 
  Ammonitiferous 
  zonal 
  divisions 
  ; 
  and 
  the 
  genus 
  JEgoceras 
  contains 
  

   about 
  30 
  species. 
  

  

  Species. 
  

  

  The 
  zone 
  of 
  iEgoceras 
  planorbis 
  yields 
  2 
  

  

  „ 
  angulatum 
  5 
  

  

  ,, 
  Arietites 
  Bucklandi 
  (lower 
  zone) 
  1 
  

  

  „ 
  „ 
  (upper 
  zone) 
  3 
  

  

  „ 
  Amatheus 
  oxynotus 
  2 
  

  

  „ 
  Arietites 
  raricostatus 
  1 
  

  

  „ 
  iEgoceras 
  Jamesoni 
  20 
  

  

  34 
  

  

  The 
  genus 
  Arietites 
  is 
  well 
  distributed 
  through 
  the 
  Lower 
  Lias, 
  

   and 
  represented 
  by 
  18 
  species. 
  

  

  Species. 
  

   The 
  zone 
  of 
  Arietites 
  Bucklandi 
  (lower 
  zone) 
  yields 
  5 
  

   „ 
  ., 
  „ 
  (upper 
  zone) 
  .... 
  6 
  

  

  „ 
  „ 
  Turneri 
  3 
  

  

  „ 
  „ 
  obtusus 
  2 
  

  

  „ 
  „ 
  raricostatus 
  2 
  

  

  18 
  

  

  The 
  family 
  Arcestidae, 
  through 
  the 
  genus 
  Amaltheus, 
  charac- 
  

  

  * 
  Martin 
  Simpson 
  describes 
  upwards 
  of 
  50 
  species 
  from 
  the 
  Lower 
  Lias 
  of 
  

   Yorkshire. 
  

  

  