﻿^°1* 
  53'] 
  FAUNA 
  OP 
  THE 
  KEISLEY 
  LIMESTONE. 
  91 
  

  

  the 
  Keisley 
  species, 
  or 
  over 
  30 
  °/ 
  of 
  the 
  whole 
  number 
  of 
  Keisley 
  

   brachiopoda, 
  have 
  been 
  recognized. 
  

  

  Schmidt 
  mentions 
  only 
  11 
  species 
  of 
  brachiopoda 
  from 
  the 
  

   Lyckholm 
  zone, 
  1 
  but 
  of 
  these 
  5 
  occur 
  at 
  Keisley. 
  Out 
  of 
  the 
  10 
  

   species 
  mentioned 
  by 
  him 
  (Joe. 
  cit.) 
  from 
  the 
  Borkholm 
  zone, 
  4 
  

   occur 
  at 
  Keisley. 
  Other 
  species 
  allied 
  to 
  British 
  forms 
  are 
  recorded 
  

   by 
  him 
  from 
  these 
  rocks. 
  Thus 
  we 
  see 
  that 
  there 
  is 
  a 
  considerable 
  

   degree 
  of 
  similarity 
  in 
  the 
  brachiopodal 
  faunas. 
  

  

  Atrypa 
  expansa 
  and 
  Orihis 
  conferta 
  appear 
  confined 
  to 
  this 
  

   horizon 
  as 
  represented 
  at 
  Keisley, 
  the 
  Chair 
  of 
  Kildare, 
  Dalecarlia 
  f 
  

   and 
  Western 
  Russia. 
  Plectambonites 
  Schmidti 
  is 
  highly 
  characteristic 
  

   of 
  it, 
  though 
  also 
  known 
  from 
  the 
  Trinucleus-sh&les 
  of 
  Sweden, 
  

   while 
  Hyattella 
  PortlocHana 
  has 
  elsewhere 
  been 
  recorded 
  only 
  

   from 
  ' 
  the 
  Upper 
  Llandeilo 
  ' 
  of 
  Balcletchie, 
  Girvan. 
  2 
  Streptis 
  

   monilifera, 
  apart 
  from 
  Kildare 
  and 
  Keisley, 
  is 
  mentioned 
  by 
  David- 
  

   son 
  only 
  from 
  the 
  'Middle 
  Llandovery' 
  of 
  Woodland 
  Point, 
  3 
  

   Girvan. 
  

  

  Three 
  species 
  are 
  peculiar 
  to 
  the 
  Keisley 
  Limestone: 
  — 
  Orihis 
  

   keisley 
  ensis, 
  Syntrophia 
  affinis, 
  and 
  Atrypina 
  similis. 
  

  

  The 
  commonest 
  species 
  of 
  brachiopoda 
  at 
  Keisley 
  are 
  Atrypa 
  

   expansa 
  (and 
  its 
  varieties), 
  Strophomena 
  corrugatella, 
  and 
  Christi- 
  

   ania 
  tenuicincta. 
  

  

  The 
  following 
  Keisley 
  species 
  are 
  found 
  also 
  in 
  the 
  Middle 
  Bala 
  

   of 
  England, 
  Wales, 
  and 
  Scotland 
  : 
  — 
  

  

  Orihis 
  calligramma, 
  0. 
  Actonice, 
  0. 
  biforata, 
  0. 
  biloba, 
  0. 
  alternata 
  y 
  

   0. 
  elegantula, 
  0. 
  flabellulum, 
  0. 
  testudinaria, 
  0. 
  vespertilio, 
  Triplecia 
  

   insularis, 
  Strophomena 
  antiquata, 
  Sir. 
  corrugatella, 
  Rajinesquina 
  

   deltoidea, 
  R. 
  expansa, 
  Leptcena 
  rhomboidalis, 
  Christiania 
  tenuicincta, 
  

   Plectambonites 
  transversalis, 
  PI. 
  quinquecostata, 
  (?) 
  Camerella 
  ? 
  

   Thomsoni. 
  

  

  Thus 
  over 
  50 
  °/ 
  oi 
  the 
  Keisley 
  species 
  occur 
  in 
  the 
  Middle 
  Bala. 
  

  

  Of 
  the 
  species 
  occurring 
  in 
  the 
  Upper 
  Bala 
  (i. 
  e. 
  the 
  beds 
  above 
  

   and 
  including 
  the 
  Staurocephalu 
  s-Limes 
  bone) 
  it 
  is 
  difficult 
  to 
  draw 
  

   up 
  a 
  satisfactory 
  list, 
  as 
  the 
  fossils 
  have 
  been 
  by 
  no 
  means 
  well 
  

   investigated. 
  From 
  lists 
  given 
  by 
  Mr. 
  Marr 
  and 
  others 
  4 
  and 
  from 
  

   specimens 
  at 
  Cambridge 
  we 
  see 
  that 
  the 
  following 
  Keisley 
  forms 
  

   occur 
  in 
  the 
  Upper 
  Bala 
  : 
  — 
  Orthis 
  Actoniw, 
  0. 
  btforata, 
  0. 
  calli- 
  

   gramma, 
  0. 
  elegantula, 
  0. 
  testudinaria, 
  0. 
  vespertilio, 
  Christiania 
  

   tenuicincta, 
  Leptama 
  rhomboidalis, 
  Plectambonites 
  quinquecostata. 
  

  

  This 
  list 
  is, 
  I 
  believe, 
  much 
  too 
  short, 
  and 
  represents 
  therefore 
  

   imperfectly 
  the 
  degree 
  of 
  aflinity 
  of 
  the 
  brachiopodal 
  faunas. 
  

  

  1 
  'Eev. 
  ostbalt. 
  Silur. 
  Trilob.,' 
  pt. 
  i. 
  Mem. 
  Acad. 
  Imp. 
  des 
  Sci. 
  St. 
  Petersbourg, 
  

   ser. 
  7, 
  vol. 
  xxx. 
  (1881) 
  no. 
  1, 
  p. 
  38; 
  and 
  Quart. 
  Journ, 
  Geol. 
  Soc. 
  vol. 
  xxxviii. 
  

   (1882) 
  p. 
  514. 
  

  

  2 
  Davidson, 
  ■ 
  Mon. 
  Brit. 
  Foss. 
  Brach.' 
  vol. 
  v. 
  (1882-84), 
  Sil. 
  Suppl. 
  p. 
  159. 
  

  

  3 
  Ibid. 
  p. 
  147. 
  

  

  4 
  Quart. 
  Journ. 
  Geol. 
  Soc. 
  vol. 
  xxxiv. 
  (1878) 
  p. 
  871, 
  vol. 
  xli. 
  (1885) 
  p. 
  476 
  y 
  

   vol. 
  xlvii. 
  (1891) 
  p. 
  500 
  ; 
  Geol. 
  Mag. 
  1892, 
  p. 
  97. 
  

  

  