﻿NEWTON 
  : 
  GEOLOGICAL 
  ZONES 
  AND 
  THEIK 
  MOLLUSCA. 
  287 
  

  

  limited 
  vertical 
  range 
  of 
  the 
  species 
  of 
  Ammonites 
  and 
  other 
  Testacea. 
  

   Similar 
  views 
  were 
  held 
  by 
  Mr. 
  C. 
  Williamson 
  ^ 
  and 
  published 
  the 
  

   same 
  3'ear, 
  he 
  recognizing 
  that 
  subdivisions 
  of 
  the 
  Lias 
  were 
  

   characterized 
  by 
  certain 
  species 
  of 
  Ammonites, 
  Belemnites, 
  and 
  other 
  

   Mollusca. 
  

  

  A 
  few 
  years 
  later 
  similar 
  zonal 
  work 
  was 
  accomplislied 
  on 
  the 
  

   Continent 
  by 
  Quenstedt,- 
  with 
  regard 
  more 
  especially 
  to 
  the 
  German 
  

   Jurassic 
  rocks, 
  and 
  he 
  was 
  followed 
  by 
  OppeP 
  in 
  the 
  same 
  direction, 
  

   his 
  remarkable 
  investigations 
  extending 
  over 
  the 
  Jurassic 
  formations 
  

   of 
  England, 
  France, 
  and 
  South-Western 
  Germany. 
  Oppel 
  recognized 
  

   the 
  importance 
  of 
  the 
  guide 
  or 
  index-fossil 
  for 
  the 
  accurate 
  

   determiuation 
  of 
  the 
  strata 
  without 
  reference 
  to 
  lithological 
  characters, 
  

   and 
  on 
  this 
  basis 
  established 
  a 
  number 
  of 
  zones 
  mainly 
  on 
  certain 
  

   species 
  of 
  the 
  Ammonites, 
  and 
  he 
  determined 
  the 
  zone 
  of 
  Ammomfe>i 
  

   raricostatus 
  as 
  the 
  highest 
  or 
  latest 
  division 
  of 
  the 
  Lower 
  Lias 
  rocks. 
  

   In 
  his 
  account 
  Oppel 
  gives 
  detailed 
  particulars 
  of 
  the 
  typical 
  

   Mollusca 
  and 
  other 
  invertebrates 
  characterizing 
  each 
  zone, 
  but 
  these 
  

   are 
  not 
  reproduced 
  in 
  the 
  present 
  notice. 
  

  

  Oppel's 
  Lias 
  zones 
  were 
  as 
  follows 
  : 
  — 
  

  

  Upper 
  Lias 
  ( 
  Zone 
  of 
  Ammonites 
  Jurensis. 
  

   or 
  Toaucien 
  ( 
  ,, 
  Posidonomya 
  Bronni. 
  

  

  The 
  chief 
  localities 
  for 
  the 
  Upper 
  Lias 
  zones 
  are 
  given 
  as 
  Whitby, 
  

   Frocester, 
  Ilminster, 
  France 
  (Caen, 
  etc.), 
  Germany 
  (Boll, 
  etc.). 
  

  

  IZone 
  of 
  Ammonites 
  spinatus. 
  

   ,, 
  A. 
  margaritatus. 
  

   ,, 
  A. 
  JDavcei. 
  

   ,, 
  A. 
  ibex. 
  

   ,, 
  A. 
  Jamesoni. 
  

   The 
  chief 
  of 
  the 
  Middle 
  Lias 
  localities 
  are 
  given 
  as 
  coast 
  of 
  

   Yorkshire, 
  Gloucestershire, 
  Charmouth 
  (Dorset), 
  France 
  (Cote 
  d'Or), 
  

   Germany. 
  

  

  / 
  Zone 
  of 
  Ammonites 
  raricostatus. 
  

   ,, 
  A. 
  oxi/notus. 
  

   Loaveh 
  Lias 
  ,, 
  A. 
  ohtusus. 
  

  

  or 
  -, 
  ,, 
  A. 
  tuberculatus. 
  

  

  Sinemukien 
  ,, 
  A. 
  Bacldancli. 
  

  

  ,, 
  A. 
  avgulatus. 
  

   ^ 
  ,, 
  A. 
  planorhis. 
  

   The 
  leading 
  localities 
  given 
  for 
  the 
  Lower 
  Lias 
  zones 
  are 
  Dorset 
  

   (Lyme 
  llegis), 
  Somerset 
  (Watchet), 
  Yorkshire 
  (Robin 
  Hood's 
  Bay), 
  

   Gloucestershire, 
  France 
  (Yonne, 
  etc.), 
  Germany 
  (Wiirtemberg). 
  

   Keuper 
  . 
  . 
  Bone-bed. 
  

   Dr. 
  Wright^ 
  published 
  in 
  1858 
  an 
  interesting 
  account 
  of 
  some 
  

   Liassic 
  fossils, 
  mostly 
  Mollusca, 
  from 
  the 
  Scottish 
  islands 
  of 
  Pabba, 
  

  

  ] 
  Trans. 
  Geol. 
  See. 
  London, 
  ser. 
  Ii, 
  vol. 
  v, 
  p. 
  223, 
  1838. 
  

  

  '^ 
  Das 
  Flozgebirge 
  Wilrttembergs, 
  1843, 
  and 
  Der 
  Jura, 
  1858. 
  

  

  ^ 
  Die 
  J'uraformaiion 
  Englancls, 
  Frankreichs, 
  und 
  des 
  sildivestlichen 
  Deutsch- 
  

  

  lands, 
  1856-8. 
  

   * 
  Quart. 
  Journ. 
  Geol. 
  Soc, 
  vol. 
  xiv, 
  p. 
  24, 
  1858. 
  

  

  