﻿408 
  

  

  PKOCEED1JSTGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  [J 
  line 
  8, 
  

  

  Gyrolepis 
  Albert 
  i, 
  G. 
  tenuistriatus, 
  and 
  jSaurichthys 
  apicalis, 
  the 
  four 
  

   latter 
  extend 
  downwards 
  into 
  the 
  Muschelkalk 
  ; 
  and, 
  of 
  the 
  Mollusca, 
  

   Pecten 
  Valoniensis 
  and 
  Pullastra 
  arenicola 
  range 
  high 
  up 
  into 
  the 
  

   Rhsetic 
  beds. 
  Gervillia 
  prcecursor, 
  Myacites 
  stnatogranulata 
  (both 
  

   found 
  by 
  Mr. 
  Moore 
  in 
  the 
  " 
  flinty 
  bed 
  " 
  at 
  Beer), 
  and 
  Beloteuthis 
  

   (Geoteuthis), 
  sp., 
  are 
  peculiar, 
  in 
  the 
  Watchet 
  section, 
  to 
  the 
  strata 
  

   below 
  the 
  bone-bed, 
  together 
  with 
  the 
  Hypsiprymnoid 
  tooth 
  and 
  

   the 
  Annelidan 
  tracks. 
  

  

  Of 
  the 
  species 
  found 
  above 
  the 
  bone-bed, 
  Pteromya 
  Crowcombeia 
  

   occurs 
  in 
  the 
  upper 
  part, 
  along 
  with 
  Hybodus 
  plicatilis, 
  Anatina 
  

   Saessi, 
  Myophoria 
  postera, 
  Lima 
  prcecursor, 
  Trigonia 
  curvirostris, 
  

   and 
  Placunopsis 
  alpina. 
  The 
  " 
  Pecten-beds 
  " 
  to 
  the 
  east 
  of 
  Watchet 
  

   and 
  the 
  Pleurophorus 
  limestone 
  (No. 
  18) 
  appear 
  to 
  be 
  the 
  best 
  defined. 
  

   Dr. 
  Wright 
  recognizes 
  the 
  former 
  at 
  Uphill. 
  

  

  § 
  IV. 
  Lower 
  Boundary 
  of 
  the 
  Bhcetic 
  Formation. 
  

   The 
  discovery 
  of 
  organic 
  remains 
  of 
  Rhaetic 
  age 
  in 
  the 
  grey 
  sandy 
  

   marlstones 
  below 
  the 
  bone-bed 
  thrusts 
  downwards 
  the 
  lower 
  boun- 
  

   dary 
  of 
  the 
  Rhsetic 
  formation 
  into 
  the 
  grey 
  marls 
  usually 
  considered 
  

   to 
  belong 
  to 
  the 
  Keuper, 
  the 
  sole 
  difference 
  between 
  the 
  fossiliferous 
  

   beds 
  at 
  Watchet 
  and 
  the 
  non-fossiliferous 
  beds 
  elsewhere 
  being 
  the 
  

   accidental 
  preservation 
  of 
  the 
  fossils 
  in 
  the 
  former 
  place. 
  Litho- 
  

   logically, 
  in 
  colour 
  and 
  texture 
  they 
  are 
  the 
  same, 
  and 
  they 
  were 
  

   deposited 
  under 
  the 
  same 
  arenaceous 
  conditions. 
  Relying, 
  there- 
  

   fore, 
  on 
  this 
  evidence, 
  I 
  should 
  include 
  the 
  grey 
  marls 
  and 
  marl- 
  

   stones, 
  and 
  black 
  shales, 
  whether 
  fossiliferous 
  or 
  not, 
  in 
  the 
  Rhsetic 
  

   formation 
  (see 
  fig. 
  1, 
  A 
  to 
  H 
  ; 
  fig. 
  2, 
  E), 
  the 
  lower 
  boundary 
  of 
  

   which 
  I 
  should 
  place 
  in 
  the 
  red 
  marls 
  below, 
  considering 
  the 
  alter- 
  

   nations 
  of 
  red 
  and 
  grey 
  marls 
  the 
  passage-beds 
  between 
  it 
  and 
  the 
  

   Keuper. 
  The 
  conglomeratic 
  bone-bed 
  — 
  the 
  old 
  boundary 
  — 
  deposited 
  

   on 
  a 
  water-worn 
  surface, 
  and 
  containing 
  pebbles 
  of 
  the 
  subjacent 
  

   rock, 
  indicates 
  a 
  break 
  in 
  the 
  succession 
  of 
  the 
  beds. 
  

  

  § 
  Y. 
  Thickness 
  of 
  the 
  Rhcetic 
  Beds 
  and 
  White 
  Lias. 
  

   The 
  following 
  table 
  shows 
  the 
  thickness 
  of 
  the 
  White 
  Lias 
  and 
  

   the 
  Rhsetic 
  formation, 
  both 
  above 
  and 
  below 
  the 
  bone-bed, 
  in 
  Somer- 
  

   setshire. 
  

  

  Locality. 
  

  

  Watchet 
  

  

  Snake 
  Lane 
  

  

  Long 
  Sutton 
  

  

  Beer 
  Crowcombe 
  (Moore) 
  

  

  High 
  Ham 
  

  

  Saltford 
  (Wright) 
  

  

  Thickness 
  of 
  Beds. 
  

  

  Rhsetic. 
  

  

  

  Grey 
  marls 
  

  

  A. 
  contort 
  a 
  

  

  White 
  

  

  below 
  bone- 
  

  

  zone 
  above 
  

  

  

  bed. 
  

  

  bone-bed. 
  

  

  

  feet. 
  

  

  feet. 
  

  

  feet. 
  

  

  84 
  

  

  20-25 
  

  

  20+ 
  

  

  11 
  + 
  

   17 
  

  

  ... 
  

  

  lOf 
  

  

  9 
  

  

  12+ 
  

  

  30 
  

  

  25 
  

  

  23 
  

  

  