﻿ANNIVERSARY 
  ADDRESS 
  OF 
  THE 
  PRESIDENT. 
  I37 
  

  

  recognize 
  five 
  zones 
  in 
  the 
  Middle 
  Lias, 
  which 
  stratigraphically 
  

   succeed 
  the 
  zone 
  of 
  Arietites 
  rancostatus. 
  

  

  The 
  following 
  six 
  species 
  of 
  Ammonites 
  are 
  constant 
  where 
  the 
  

   beds 
  are 
  fully 
  developed, 
  and 
  constitute 
  the 
  recognized 
  zonal 
  forms, 
  

   also 
  reading 
  upwards 
  : 
  — 
  

  

  6. 
  Amaltheus 
  (Ammonites) 
  spinatus, 
  Brug. 
  

  

  5. 
  Amaltheus 
  (Ammonites) 
  margaritatus, 
  Montf. 
  

  

  4. 
  JEgoceras 
  (Ammonites) 
  Henleyi, 
  Sow. 
  

  

  3. 
  Amaltheus 
  (Ammonites) 
  ibex, 
  Quenst. 
  

  

  2. 
  JEgoceras 
  (Ammonites) 
  Jamesoni, 
  Sow. 
  

  

  1. 
  JEgoceras 
  (Ammonites) 
  armatum. 
  

  

  Associated 
  with 
  these 
  species 
  there 
  also 
  occurs 
  an 
  assemblage 
  of 
  

   species 
  of 
  other 
  Mollusca 
  which 
  at 
  once 
  distinguishes 
  the 
  Middle 
  

   from 
  the 
  Lower 
  and 
  Upper 
  Lias. 
  

  

  The 
  clays, 
  shales, 
  and 
  sands 
  of 
  the 
  Upper 
  Lias, 
  when 
  occurring 
  in 
  

   a 
  complete 
  section, 
  are 
  divided 
  into 
  eleven 
  well-defined 
  and 
  recog- 
  

   nizable 
  zones. 
  The 
  sandy 
  or 
  upper 
  portion 
  of 
  this 
  stage, 
  the 
  Upper 
  

   Lias 
  sands, 
  or 
  "Midford 
  Sands"*, 
  are 
  chiefly 
  characterized 
  by 
  the 
  

   two 
  groups 
  Harpoceras 
  and 
  Lytoceras. 
  

  

  In 
  Gloucestershire 
  and 
  Somersetshire 
  they 
  include 
  six 
  zones, 
  

   characterized 
  by 
  

  

  6. 
  Harpoceras 
  (Ammonites) 
  opalinum, 
  Rein. 
  

  

  5. 
  Harpoceras 
  (Ammonites) 
  radians, 
  Schloth. 
  

  

  4. 
  Harpoceras 
  (Ammonites) 
  Thouarsense, 
  d'Orb. 
  

  

  3. 
  Haipoceras 
  (Ammonites) 
  insigne, 
  Schiibl. 
  

  

  2. 
  Lytoceras 
  (Ammonites) 
  jurense, 
  Ziet. 
  

  

  1. 
  Lytoceras 
  (Ammonites) 
  hircinum, 
  Schiibl. 
  

  

  The 
  lower 
  portion 
  of 
  the 
  Upper 
  Lias, 
  consisting 
  of 
  clays 
  varying 
  

   in 
  consistency 
  and 
  colour 
  (black 
  in 
  Yorkshire, 
  dark 
  grey 
  in 
  the 
  

   Midland 
  counties, 
  and 
  pale 
  grey 
  or 
  pale 
  brown 
  in 
  Somersetshire 
  and 
  

   Dorsetshire), 
  is 
  everywhere 
  distinguished 
  by 
  

  

  5. 
  Harpoceras 
  (Ammonites) 
  bifrons, 
  Brug. 
  

  

  4. 
  Harpoceras 
  (Ammonites) 
  serpentinum, 
  Schloth. 
  

  

  3. 
  Stephanoceras 
  (Ammonites) 
  commune, 
  Sow. 
  

  

  2. 
  Stephanoceras 
  (Ammonites) 
  anguinum, 
  Rein. 
  

   1. 
  Stephanoceras 
  (Ammonites) 
  jibulatum, 
  Sow. 
  

  

  The 
  grand 
  cliff 
  sections 
  of 
  the 
  Yorkshire 
  coast 
  exhibit 
  almost 
  

   every 
  zone 
  in 
  all 
  three 
  of 
  the 
  above 
  divisions, 
  except 
  those 
  of 
  JEgo- 
  

   ceras 
  angulatum 
  and 
  JE. 
  planorbis, 
  both 
  of 
  which 
  are 
  concealed 
  

   beneath 
  the 
  German 
  Ocean 
  at 
  Robin 
  Hood's 
  Bay 
  and 
  at 
  Redcar, 
  

   although 
  in 
  both 
  localities 
  the 
  beds 
  occur. 
  

  

  Probably 
  the 
  most 
  complete 
  continuous 
  section 
  in 
  Europe 
  is 
  com- 
  

   prised 
  in 
  the 
  succession 
  exhibited 
  along 
  the 
  Dorsetshire 
  coast 
  from 
  

   Pinhay 
  Bay, 
  west 
  of 
  Lyme 
  Regis, 
  to 
  Burton 
  Bradstock, 
  east 
  of 
  

   Bridport 
  Harbour. 
  The 
  shore 
  west 
  of 
  Lyme 
  Regis, 
  Black 
  Yen 
  near 
  

   Lyme, 
  and 
  Charmouth, 
  Westhay, 
  Golden 
  Cap, 
  Eype 
  Down, 
  &c. 
  are, 
  

  

  * 
  Phillips, 
  ' 
  Geol. 
  of 
  Oxford 
  and 
  Thames 
  Valley,' 
  p. 
  118 
  (1871). 
  

  

  