﻿550 
  PROP. 
  C, 
  LAPWOETH 
  ON 
  THE 
  OIEVAN 
  SUCCESSION-. 
  

  

  of 
  Penwhapple 
  and 
  Ardwell 
  and 
  the 
  Tri 
  nucleus-beds 
  of 
  Drummuck 
  

   being 
  there 
  placed 
  for 
  the 
  first 
  time 
  in 
  their 
  proper 
  relative 
  position, 
  

   bnt 
  erroneously 
  assigned 
  to 
  the 
  Llandovery*. 
  

  

  The 
  same 
  year 
  Professor 
  A. 
  Geikie 
  published 
  his 
  Geological 
  Map 
  of 
  

   Scotland, 
  extending 
  his 
  classification 
  of 
  the 
  Lower 
  Palaeozoic 
  rocks 
  

   of 
  the 
  Uplands 
  into 
  the 
  Girvan 
  region, 
  replacing 
  the 
  Benan 
  boulder- 
  

   beds 
  in 
  the 
  Silurian, 
  and 
  restricting 
  the 
  Caradoc 
  colour 
  to 
  the 
  Penan 
  

   zone 
  and 
  the 
  northern 
  inlier 
  of 
  Mulloch 
  Hill 
  and 
  Craighead. 
  

  

  The 
  host 
  of 
  palwontological 
  works 
  already 
  published 
  treating 
  of 
  

   the 
  Lower 
  Palaeozoic 
  fossils 
  of 
  this 
  region 
  make 
  frequent 
  references 
  

   to 
  the 
  probable 
  geological 
  age 
  of 
  the 
  more 
  prolific 
  fossil-bearing 
  

   zones. 
  The 
  large 
  collections 
  originally 
  made 
  for 
  Professor 
  Sedg- 
  

   wick 
  afforded 
  many 
  of 
  the 
  most 
  striking 
  types 
  of 
  Silurian 
  organisms 
  

   figured 
  in 
  Sedgwick 
  and 
  M'Coy's 
  ' 
  Palaeozoic 
  Rocks 
  and 
  Fossils.' 
  

   Throughout 
  that 
  classical 
  work 
  are 
  scattered 
  frequent 
  allusions 
  to 
  

   the 
  probable 
  parallelisms 
  of 
  Girvan 
  beds 
  and 
  their 
  prototypes 
  in 
  

   Wales 
  and 
  the 
  west 
  of 
  England. 
  In 
  the 
  Supplement 
  to 
  this 
  work, 
  

   issued 
  under 
  Salter's 
  care, 
  subsequent 
  to 
  the 
  death 
  of 
  Professor 
  

   Sedgwick, 
  these 
  references 
  are 
  most 
  accurate 
  and 
  valuable. 
  

  

  The 
  four 
  successive 
  instalments 
  of 
  Mr. 
  Salter's 
  unfinished 
  Mono- 
  

   graph 
  of 
  the 
  British 
  Trilobites 
  contain 
  several 
  peculiar 
  types 
  of 
  

   Crustacea 
  from 
  this 
  area 
  ; 
  and 
  the 
  author, 
  foundiag 
  solely 
  upon 
  the 
  

   palaeontological 
  evidence 
  before 
  him, 
  as 
  interpreted 
  by 
  his 
  intimate 
  

   knowledge 
  of 
  the 
  vertical 
  distribution 
  of 
  Trilobites 
  in 
  the 
  Lower 
  

   Palaeozoic 
  rocks 
  of 
  Wales, 
  invariably 
  assigns 
  theStinchar 
  Limestone 
  

   to 
  the 
  Llandeilo, 
  the 
  Penwhapple 
  Grits 
  to 
  the 
  Caradoc, 
  and 
  the 
  

   Mulloch-Hill 
  Sandstone 
  and 
  the 
  Pentamerus-beds 
  of 
  Saugh 
  Hill 
  to 
  

   Murchison's 
  transitional 
  formation 
  of 
  the 
  Llandovery. 
  

  

  The 
  corresponding 
  Monograph 
  of 
  the 
  Silurian 
  Brachiopoda, 
  which 
  

   forms 
  the 
  final 
  division 
  of 
  Mr. 
  Davidson's 
  great 
  work, 
  is 
  greatly 
  

   enriched 
  by 
  forms 
  derived 
  from 
  the 
  Girvan 
  region 
  ; 
  and 
  though 
  the 
  

   author 
  is 
  naturally 
  less 
  confident 
  in 
  his 
  geological 
  deductions 
  than 
  

   Mr. 
  Salter, 
  his 
  correlations 
  are 
  generally 
  identical 
  with 
  those 
  of 
  

   that 
  palaeontologist. 
  

  

  In 
  1867, 
  Professor 
  Wyville 
  Thomson 
  described 
  and 
  figured 
  

   some 
  forms 
  of 
  Graptolites 
  from 
  the 
  Girvan 
  area, 
  and 
  on 
  palaeonto- 
  

   logical 
  grounds 
  suggested 
  a 
  material 
  modification 
  of 
  Murchison's 
  

   views 
  of 
  the 
  succession, 
  expressing 
  his 
  own 
  opinion 
  that 
  the 
  whole 
  

   of 
  the 
  Girvan 
  rocks 
  belong 
  to 
  Murchison's 
  Lower 
  Silurian, 
  and 
  that 
  

   the 
  Orthoceratite-flagstones 
  of 
  Penwhapple 
  should 
  be 
  placed 
  at 
  the 
  

   base 
  instead 
  of 
  the 
  summit 
  of 
  the 
  series, 
  and 
  are 
  probably 
  followed 
  

   in 
  ascending 
  sequence 
  by 
  the 
  Mulloch-Hill 
  Sandstones, 
  Craighead 
  

   Limestones, 
  and 
  Pentamerus- 
  or 
  Saugh-Hill 
  Grits. 
  

  

  The 
  officers 
  of 
  the 
  Geological 
  Survey 
  of 
  Scotland 
  have 
  made 
  im- 
  

   portant 
  collections 
  from 
  the 
  rocks 
  of 
  the 
  Girvan 
  district. 
  A 
  list 
  of 
  

   their 
  species 
  is 
  appended 
  to 
  the 
  " 
  Explanation 
  of 
  Sheet 
  3," 
  pub- 
  

   lished 
  in 
  1873; 
  and 
  upon 
  the 
  ground 
  of 
  the 
  palaeontological 
  evidences 
  

   they 
  afford, 
  Professor 
  Geikie 
  rightly 
  concludes 
  that 
  in 
  the 
  " 
  south- 
  

  

  * 
  Catalogue 
  of 
  Western 
  Scottish 
  Fossils. 
  1876, 
  pp. 
  13 
  and 
  2. 
  Compare 
  also 
  

   Lapworth 
  ,Trans. 
  Geol. 
  Soc. 
  Glasgow, 
  1879, 
  pp. 
  78-84. 
  

  

  