﻿594 
  3IK. 
  G. 
  W. 
  IAXPLTJGH 
  OS 
  THE 
  

  

  the 
  great 
  abundance 
  of 
  specimens 
  of 
  Criocems. 
  The 
  space 
  between 
  

   the 
  two 
  bands 
  is 
  held 
  by 
  dark 
  clay 
  in 
  ^Yhich 
  a 
  variety 
  of 
  Amm. 
  spee- 
  

   tonensis 
  is 
  tolerably 
  abundant. 
  

  

  In 
  these 
  nodules, 
  the* 
  Crioceratites 
  are 
  not 
  very 
  large, 
  but 
  in 
  a 
  

   third 
  bed 
  4| 
  feet 
  higher, 
  in 
  which 
  here 
  and 
  there 
  lenticular 
  masses 
  

   of 
  ferruginous 
  stone 
  are 
  developed, 
  the 
  specimens 
  are 
  of 
  a 
  different 
  

   species, 
  and 
  often 
  very 
  large 
  in 
  size. 
  

  

  In 
  the 
  list 
  given 
  at 
  p. 
  597 
  the 
  fossils 
  of 
  the 
  2foricns-bed 
  will 
  be 
  

   found 
  separately 
  indicated. 
  It 
  will 
  be 
  seen 
  that 
  several 
  other 
  

   species 
  of 
  Ammonites 
  occur, 
  but 
  Ammonites 
  noricus 
  is 
  throughout 
  

   clearly 
  predominant, 
  the 
  other 
  forms 
  being 
  represented 
  only 
  by 
  rare 
  

   and 
  scattered 
  specimens. 
  

  

  Amm. 
  speetonensis-6<?cZs. 
  — 
  This 
  variable 
  and 
  difficult 
  species 
  makes 
  

   its 
  first 
  appearance, 
  as 
  just 
  mentioned, 
  in 
  the 
  band 
  of 
  clay 
  between 
  

   the 
  two 
  nodular 
  Crioceras-b&n&s. 
  The 
  variety 
  found 
  here 
  has 
  very 
  

   coarse 
  ribs 
  and 
  is 
  an 
  extreme 
  form 
  of 
  Amm. 
  concinnus, 
  Phillips 
  ; 
  

   a 
  little 
  higher 
  in 
  the 
  section 
  it 
  is 
  accompanied, 
  and 
  in 
  great 
  part 
  re- 
  

   placed, 
  by 
  the 
  fine-ribbed 
  variety 
  Amm. 
  venustus, 
  Phil. 
  The 
  species 
  

   speedily 
  attains 
  its 
  greatest 
  development, 
  being 
  most 
  abundant 
  in 
  a 
  

   thick 
  bed 
  of 
  dark 
  splintery 
  shaly 
  clay 
  (C 
  6), 
  where 
  it 
  is 
  surrounded 
  

   by 
  a 
  well-preserved 
  and 
  extensive 
  fauna. 
  

  

  Above 
  this 
  fossiliferous 
  bed 
  we 
  have 
  a 
  considerable 
  thickness 
  of 
  

   banded 
  clays, 
  alternately 
  pale 
  and 
  dark 
  blue, 
  but 
  with 
  the 
  dark 
  

   tint 
  predominating, 
  in 
  which 
  fossils 
  of 
  any 
  kind 
  are 
  rare, 
  though 
  

   Bel. 
  jacidum 
  may 
  be 
  traced 
  throughout. 
  The 
  beds 
  of 
  this 
  horizon 
  

   are 
  not 
  often 
  exposed 
  on 
  the 
  beach, 
  and 
  their 
  outcrop 
  in 
  the 
  cliff- 
  

   foot 
  is 
  hidden 
  by 
  the 
  great 
  slip 
  in 
  Black 
  Cliff, 
  so 
  that 
  opportunities 
  

   for 
  studying 
  them 
  are 
  rare 
  ; 
  but 
  I 
  have 
  seen 
  them 
  several 
  times, 
  

   and 
  can 
  confirm 
  Leckenby's 
  statement 
  that 
  they 
  are 
  sparingly 
  

   fossiliferous. 
  I 
  have 
  not 
  yet 
  found 
  Amm. 
  speetonensis 
  in 
  them, 
  but 
  

   it 
  is 
  probably 
  not 
  absent, 
  as 
  it 
  is 
  of 
  frequent 
  occurrence 
  higher 
  in 
  

   the 
  section. 
  

  

  A 
  marked 
  feature 
  in 
  the 
  clays 
  from 
  the 
  base 
  of 
  the 
  Sjieetonensis- 
  

   beds 
  upwards 
  to 
  the 
  top 
  of 
  the 
  zone 
  of 
  Bel. 
  jaculum, 
  and 
  for 
  some 
  

   little 
  distance 
  beyond, 
  is 
  the 
  frequent 
  recurrence 
  of 
  irregular 
  len- 
  

   ticular 
  beds 
  of 
  indurated 
  ferruginous 
  marl- 
  or 
  clay-stone, 
  which 
  

   form 
  along 
  nearly 
  every 
  line 
  of 
  nodules. 
  These 
  hard 
  bands 
  form 
  

   miniature 
  broken 
  reefs 
  of 
  greyish 
  stone 
  in 
  the 
  shore-exposures 
  ; 
  

   but 
  in 
  the 
  cliff 
  they 
  weather 
  down 
  into 
  a 
  red 
  stain, 
  which 
  may 
  

   be 
  seen 
  in 
  conspicuous 
  bands 
  along 
  the 
  south 
  side 
  of 
  the 
  ridge 
  

   separating 
  Black 
  Cliff 
  from 
  Middle 
  Cliff. 
  In 
  Lincolnshire, 
  as 
  is 
  

   well 
  known, 
  there 
  is 
  a 
  great 
  development 
  of 
  workable 
  ironstone 
  of 
  

   this 
  age. 
  

  

  Supposed 
  " 
  Middle 
  Seocomian" 
  — 
  I 
  am 
  inclined 
  to 
  think 
  that 
  the 
  

   beds 
  above 
  C 
  5 
  of 
  fig. 
  5 
  fall 
  within 
  the 
  range 
  of 
  the 
  Middle 
  Neoco- 
  

   mian 
  of 
  Judd, 
  who 
  defines 
  the 
  base 
  of 
  this 
  division 
  as 
  being 
  formed 
  

   by 
  the 
  " 
  Ancl/loceras-'bea\s, 
  ,, 
  described 
  as 
  dark 
  blue 
  clays, 
  the 
  metro- 
  

   polis 
  of 
  Bel. 
  jacidum, 
  with 
  regular 
  layers 
  of 
  septaria, 
  and 
  in 
  which 
  

   Ancyloceras 
  attains 
  the 
  maximum 
  of 
  abundance. 
  This 
  description 
  

   applies 
  best 
  to 
  the 
  above-described 
  Crioceras-be&s 
  at 
  the 
  top 
  of 
  the 
  

  

  