﻿1864.] 
  KIRKBY 
  PEBMIAN 
  FISH 
  AND 
  PLANTS. 
  349 
  

  

  very 
  rarely 
  traces 
  of 
  the 
  vertebral 
  processes. 
  The 
  specimens 
  are 
  

   sparingly 
  distributed 
  in 
  the 
  bed, 
  occurring 
  generally 
  as 
  isolated 
  

   individuals 
  ; 
  still, 
  a 
  pair 
  of 
  individuals, 
  aud 
  sometimes 
  a 
  trio, 
  are 
  

   occasionally 
  found 
  together 
  on 
  a 
  plane 
  surface 
  of 
  a 
  few 
  square 
  feet. 
  

   Such 
  instances, 
  however, 
  are 
  exceptional 
  ; 
  and, 
  notwithstanding 
  that 
  

   probably 
  some 
  hundreds 
  of 
  specimens 
  have 
  been 
  found 
  since 
  their 
  

   first 
  discovery, 
  they 
  cannot 
  be 
  described 
  as 
  common, 
  the 
  quantity 
  

   of 
  specimens 
  obtained 
  being 
  due 
  rather 
  to 
  extensive 
  and 
  close 
  re- 
  

   search 
  than 
  to 
  their 
  own 
  abundance. 
  

  

  Fully 
  nine-tenths 
  of 
  the 
  specimens 
  found 
  belong 
  to 
  a 
  single 
  species 
  

   of 
  Palceoniscus. 
  The 
  remainder 
  belong 
  to 
  two 
  or 
  probably 
  three 
  

   species 
  of 
  the 
  same 
  genus, 
  and 
  to 
  a 
  species 
  of 
  Acrolepis. 
  All 
  the 
  

   Palceonisci 
  are 
  small, 
  the 
  largest 
  of 
  the 
  forms 
  being 
  but 
  little 
  more 
  

   than 
  four 
  inches 
  in 
  length. 
  The 
  Acrolepis 
  seems 
  to 
  have 
  attained 
  a 
  

   length 
  of 
  twelve 
  inches. 
  

  

  Associated 
  with 
  the 
  Fish-remains, 
  there 
  have 
  also 
  rarely 
  occurred 
  

   some 
  fragments 
  of 
  Plants. 
  These, 
  though 
  very 
  imperfectly 
  preserved, 
  

   appear 
  to 
  be 
  referable 
  to 
  three 
  species, 
  one 
  of 
  which 
  is 
  a 
  Catamites, 
  

   two 
  Ulmannice, 
  and 
  the 
  fourth 
  is 
  a 
  large 
  reed-like 
  form, 
  whose 
  

   generic 
  relations 
  are 
  difficult 
  to 
  determine 
  from 
  the 
  discovered 
  

   fragments. 
  These 
  are 
  the 
  only 
  fossils 
  that 
  have 
  been 
  met 
  with 
  

   along 
  with 
  the 
  Fish. 
  No 
  traces 
  of 
  Mollusca 
  occur 
  with 
  them, 
  nor, 
  

   as 
  yet, 
  of 
  Entomostraca 
  or 
  other 
  microzoa, 
  though 
  several 
  representa- 
  

   tives 
  of 
  these 
  classes 
  are 
  pretty 
  commonly 
  distributed 
  in 
  other 
  parts 
  

   of 
  the 
  Upper 
  Limestone. 
  

  

  It 
  has 
  already 
  been 
  remarked 
  that 
  the 
  fossils 
  are 
  not 
  altogether 
  

   confined 
  to 
  the 
  stratum 
  designated 
  the 
  Fish-bed 
  ; 
  they 
  are 
  compa- 
  

   ratively 
  most 
  abundant 
  in 
  that 
  zone, 
  and 
  it 
  is 
  almost 
  only 
  there 
  

   where 
  there 
  is 
  a 
  probability 
  of 
  finding 
  them 
  by 
  personal 
  search, 
  

   their 
  occurrence 
  on 
  other 
  horizons 
  being 
  so 
  rare 
  as 
  nearly 
  always 
  to 
  

   be 
  the 
  result 
  of 
  accidental 
  observation 
  rather 
  than 
  the 
  reward 
  of 
  

   direct 
  investigation. 
  Still, 
  as 
  they 
  do 
  occur 
  at 
  other 
  horizons, 
  it 
  is 
  

   important 
  that 
  we 
  should 
  place 
  on 
  record 
  all 
  that 
  is 
  known 
  of 
  their 
  

   vertical 
  range. 
  

  

  Commencing 
  from 
  below, 
  the 
  fossils 
  first 
  appear 
  in 
  the 
  soft 
  lami- 
  

   nated 
  marls 
  at 
  the 
  base 
  of 
  the 
  Upper 
  Limestone, 
  at 
  the 
  point 
  marked 
  

   A 
  in 
  fig. 
  1 
  ; 
  from 
  this 
  horizon 
  two 
  imperfectly 
  preserved 
  examples 
  

   of 
  the 
  common 
  form, 
  Palwoniscus 
  varians, 
  have 
  been 
  obtained. 
  

   In 
  the 
  slaty 
  argillaceous 
  limestone 
  immediately 
  overlying 
  the 
  last- 
  

   named 
  bed, 
  and 
  marked 
  B 
  in 
  the 
  section, 
  a 
  single 
  specimen 
  of 
  

   Uhnannia, 
  sp. 
  indet., 
  has 
  been 
  met 
  with 
  ; 
  and 
  in 
  the 
  soft 
  yellow 
  

   limestone, 
  marked 
  C 
  in 
  the 
  section, 
  about 
  five 
  or 
  six 
  feet 
  higher 
  in 
  

   the 
  series, 
  several 
  obscure 
  fragments 
  of 
  vegetables 
  have 
  occurred. 
  

   In 
  the 
  concretionary 
  and 
  lamino-concretionary 
  beds 
  marked 
  D, 
  

   lying 
  between 
  the 
  last-named 
  and 
  the 
  Fish-bed, 
  several 
  imperfect 
  

   specimens 
  of 
  P. 
  varians 
  have 
  been 
  observed, 
  and 
  more 
  particularly 
  

   on 
  the 
  uppermost 
  surface-plane 
  on 
  which 
  the 
  Fish 
  -bed 
  rests, 
  where, 
  

   besides 
  P. 
  varians, 
  there 
  have 
  occurred 
  specimens 
  of 
  Acrolepis. 
  In 
  

   the 
  Fish-bed 
  proper 
  have 
  been 
  obtained 
  the 
  four 
  Palceonisci, 
  namely, 
  

   P. 
  varians, 
  P. 
  alius, 
  P, 
  Abbsii, 
  and 
  P. 
  angustus 
  ?, 
  the 
  Acrolepis, 
  and 
  

  

  VOL. 
  XX, 
  — 
  PART 
  I. 
  2 
  C 
  

  

  