﻿PROF. 
  C. 
  LAP 
  WORTH 
  ON 
  THE 
  GrIRYAN 
  SUCCESSION. 
  

  

  647 
  

  

  Rastrites 
  maximus, 
  Carr. 
  

   Monograptus 
  turriculatus, 
  Bart. 
  

  

  crassus, 
  Lapw. 
  

  

  Hisingeri, 
  Carr. 
  

  

  Monograptus 
  runcinatus, 
  Lapw. 
  

   Diplograptus 
  pahneus, 
  Barr. 
  

   Peltocaris 
  aptycboides, 
  Salt. 
  

  

  These 
  Rastntes-maximus 
  mudstones 
  pass 
  upwards 
  into 
  a 
  group 
  of 
  

   massive 
  yellow 
  gritstones 
  very 
  similar, 
  in 
  their 
  petrological 
  cha- 
  

   racters, 
  to 
  those 
  which 
  succeed 
  to 
  the 
  M.-Sedgwickii 
  zone. 
  They 
  

   resemble 
  these 
  beds 
  most 
  especially 
  in 
  their 
  pale 
  blue 
  matrix, 
  and 
  in 
  

   containing 
  a 
  notable 
  proportion 
  of 
  calcareous 
  matter, 
  but 
  differ 
  from 
  

   them 
  in 
  the 
  absence 
  of 
  the 
  fine 
  seams 
  of 
  pebbles 
  and 
  in 
  the 
  total 
  

   want 
  of 
  organic 
  remains. 
  About 
  60 
  feet 
  of 
  these 
  pale 
  yellow 
  grit- 
  

   stones 
  are 
  here 
  exposed, 
  aud 
  form 
  the 
  final 
  member 
  of 
  this 
  first 
  or 
  

   Camregan 
  group, 
  the 
  purple 
  sandstones 
  and 
  shales 
  which 
  follow 
  

   belonging 
  more 
  naturally 
  to 
  the 
  overlying 
  and 
  succeeding 
  Crosso- 
  

   podia- 
  or 
  Purple 
  Shale 
  formation. 
  

  

  Extension 
  of 
  Camregan 
  Beds 
  to 
  the 
  East 
  of 
  Penwhapple 
  Glen. 
  — 
  

   This 
  marked 
  group 
  of 
  fossiliferous 
  gritstones, 
  calcareous 
  flag- 
  

   stones, 
  and 
  Graptolitiferous 
  shales 
  is 
  traceable 
  up 
  the 
  left 
  side 
  of 
  

   the 
  stream 
  into 
  the 
  wood 
  of 
  Camregan, 
  where 
  the 
  shell-bearing 
  

   gritstones 
  are 
  laid 
  open 
  in 
  several 
  quarries 
  near 
  the 
  northern 
  edge 
  

   of 
  the 
  wood. 
  Here 
  these 
  grits 
  are 
  softer 
  and 
  looser 
  in 
  texture 
  than 
  

   in 
  the 
  burn 
  itself, 
  and 
  their 
  fossils 
  are 
  procurable 
  with 
  comparative 
  

   ease. 
  They 
  are 
  crowded 
  with 
  casts 
  of 
  Brachiopoda, 
  which 
  are 
  so 
  

   abundant 
  in 
  certain 
  seams 
  as 
  irresistibly 
  to 
  recall 
  to 
  mind 
  the 
  won- 
  

   derfully 
  prolific 
  shelly 
  sandstones 
  of 
  AEulloch 
  Hill, 
  on 
  the 
  north 
  of 
  

   the 
  Girvan 
  valley. 
  The 
  beds, 
  too, 
  have 
  the 
  same 
  coarse 
  sandy 
  

   texture, 
  calcareous 
  and 
  gritty 
  composition, 
  and 
  more 
  or 
  less 
  flaggy 
  

   fracture. 
  

  

  It 
  is 
  this 
  locality 
  which 
  gives 
  its 
  name 
  to 
  the 
  band, 
  as 
  it 
  is 
  the 
  

   only 
  spot 
  upon 
  its 
  entire 
  course 
  through 
  the 
  Girvan 
  district 
  where 
  

   it 
  is 
  possible 
  to 
  find 
  a 
  local 
  name 
  geographically 
  significant 
  of 
  the 
  

   group, 
  and 
  at 
  the 
  same 
  time 
  sufficiently 
  definite 
  in 
  its 
  application 
  to 
  

   prevent 
  ambiguity. 
  The 
  commonest 
  fossils 
  I 
  have 
  collected 
  here 
  

   are 
  : 
  — 
  

  

  Rhynchonella 
  llandoveriana. 
  

   Atrypa 
  hemisphserica. 
  

  

  Tentaeulites 
  ornatus. 
  

   Encrinurus 
  punctatus. 
  

  

  I 
  am 
  not 
  able 
  to 
  refer 
  these 
  beds 
  to 
  their 
  exact 
  horizon 
  in 
  the 
  

   section 
  of 
  the 
  Camregan 
  group 
  as 
  exhibited 
  in 
  the 
  gorge 
  of 
  Pen- 
  

   whapple; 
  but 
  I 
  suspect 
  that 
  they 
  belong 
  generally 
  to 
  the 
  gritty 
  flags 
  

   with 
  Rhynchonella, 
  found 
  in 
  contact 
  with 
  the 
  Monograptus-Sedgwickii 
  

   zone. 
  

  

  In 
  the 
  continuation 
  of 
  the 
  same 
  line 
  of 
  strike 
  to 
  the 
  eastward 
  

   beyond 
  the 
  limits 
  of 
  the 
  wood 
  we 
  find 
  a 
  small 
  section 
  of 
  the 
  Cam- 
  

   regan 
  beds 
  at 
  the 
  head 
  of 
  a 
  small 
  burn 
  running 
  down 
  the 
  hill-slope 
  

   to 
  the 
  west 
  of 
  the 
  fence. 
  Here 
  only 
  a 
  few 
  flaggy 
  grits 
  and 
  shales 
  

   are 
  seen 
  ; 
  but 
  they 
  contain 
  the 
  usual 
  types 
  of 
  the 
  Camregan 
  lime- 
  

   stone, 
  such 
  as 
  : 
  — 
  

  

  Encrinurus 
  punctatus. 
  

   Atrypa 
  hemisphserica. 
  

  

  Rhynchonella. 
  

   Pentamerus 
  oblongus. 
  

  

  