﻿70 
  ME. 
  P. 
  K. 
  COWPER 
  REED 
  ON 
  THE 
  [Feb. 
  1897,. 
  

  

  Orthis 
  (Dalmanella) 
  elegantula 
  ?, 
  Dalman. 
  

  

  Orthis 
  (Heterorthis) 
  alternata 
  ?, 
  Sowerby. 
  

  

  Orthis 
  (Dinorthis) 
  plabelltjlttm 
  ?, 
  Sowerby. 
  

  

  These 
  three 
  species 
  have 
  been 
  doubtfully 
  identified 
  from 
  frag- 
  

   mentary 
  specimens. 
  

  

  Strophomena 
  antiqttata, 
  Sowerby. 
  

  

  A 
  fairly 
  common 
  species 
  at 
  Keisley 
  ; 
  it 
  is 
  found 
  in 
  the 
  Bala, 
  as- 
  

   well 
  as 
  in 
  the 
  Silurian 
  of 
  Britain. 
  

  

  Strophomena 
  corrtjgatella, 
  Davidson. 
  

  

  This 
  is 
  one 
  of 
  the 
  commonest 
  species 
  at 
  Keisley, 
  and 
  is 
  also- 
  

   found 
  at 
  the 
  Chair 
  of 
  Kildare 
  and 
  in 
  the 
  Leptcena-Jjimeatone. 
  

  

  Lept^na 
  rhomboidalis, 
  Wilckens. 
  

  

  This 
  species, 
  commonly 
  but 
  erroneously 
  l 
  called 
  Stropliomena 
  

   rhomboidalis, 
  is 
  not 
  abundant 
  in 
  the 
  Keisley 
  Limestone, 
  but 
  it 
  has 
  

   been 
  recorded 
  thence 
  by 
  Harkness, 
  Marr, 
  and 
  Nicholson, 
  and 
  I 
  have 
  

   found 
  good 
  typical 
  specimens 
  of 
  it 
  myself. 
  It 
  occurs 
  also 
  in 
  the 
  

   Kildare 
  Limestone 
  and 
  in 
  the 
  Dalecarlian 
  Limestone. 
  

  

  Plectambonites 
  Schmidti, 
  Tornquist. 
  

  

  It 
  is 
  of 
  considerable 
  importance 
  that 
  this 
  species 
  has 
  been 
  recog- 
  

   nized 
  at 
  Keisley, 
  for 
  it 
  appears 
  to 
  be 
  nearly 
  restricted 
  to 
  the 
  horizon 
  

   of 
  the 
  Zep^na-Limestone 
  and 
  Stage 
  F 
  of 
  Schmidt. 
  I 
  have 
  not 
  seen 
  

   any 
  specimens 
  from 
  Kildare, 
  but 
  the 
  Keisley 
  examples 
  show 
  all 
  the 
  

   features 
  described 
  by 
  Lindstrom. 
  2 
  

  

  Plectambonites 
  quinqtjecostata, 
  M'Coy. 
  

  

  Tornquist 
  3 
  compares 
  a 
  Leptcena- 
  Limestone 
  species 
  with 
  this 
  one 
  of 
  

   M'Coy's, 
  but 
  it 
  is 
  not 
  given 
  in 
  the 
  ' 
  List 
  of 
  the 
  Fossil 
  Faunas 
  of 
  

   Sweden 
  ' 
  (Stockholm, 
  1888). 
  It 
  is 
  fairly 
  common 
  at 
  Keisley 
  and 
  

   Kildare. 
  

  

  Plectambonites 
  transversalis 
  ?, 
  Wahlenberg. 
  

  

  I 
  believe 
  that 
  this 
  species 
  occurs 
  at 
  Keisley, 
  but 
  the 
  specimens 
  

   are 
  rather 
  imperfect. 
  It 
  occurs 
  also 
  doubtfully 
  at 
  Kildare. 
  It 
  is 
  

   known 
  from 
  Bala, 
  Llandovery, 
  and 
  Wenlock 
  rocks 
  in 
  the 
  United 
  

   Kingdom. 
  4 
  

  

  Eafinesqulna 
  expansa, 
  Sowerby. 
  

  

  There 
  is 
  a 
  well-preserved 
  ventral 
  valve 
  of 
  this 
  species 
  at 
  Carlisle, 
  

   and 
  I 
  have 
  seen 
  other 
  fragments. 
  Davidson 
  5 
  states 
  that 
  this 
  form 
  

   is 
  found 
  in 
  the 
  Caradoc 
  and 
  Lower 
  Llandovery. 
  

  

  1 
  Hall 
  & 
  Clarke, 
  'Pal. 
  N. 
  Y./ 
  vol. 
  viii. 
  Brach. 
  pt. 
  i. 
  (1892) 
  pp. 
  250 
  & 
  276.; 
  

  

  2 
  ' 
  Fragm. 
  Silur.' 
  (1880) 
  p. 
  29, 
  pi. 
  xiv. 
  figs. 
  25, 
  26. 
  

  

  3 
  ' 
  Ofvers. 
  6. 
  Bergbyggn. 
  mom 
  Siljans. 
  i 
  Dal.' 
  p. 
  26, 
  Sveriges 
  Geol. 
  

   Undersokn. 
  ser. 
  C, 
  no. 
  57 
  (Stockholm, 
  1883). 
  

  

  4 
  Davidson, 
  ' 
  Mon. 
  Brit. 
  Foss. 
  Brach.,' 
  vol. 
  hi. 
  (1864-71) 
  p. 
  320 
  {Leptcena,. 
  

   transversalis). 
  

  

  5 
  Ibid. 
  p. 
  314 
  (Strophomena 
  expansa). 
  

  

  