﻿A 
  NOTABLE 
  TRILOBITE 
  FROM 
  THE 
  PERCE 
  ROCK 
  

  

  BY 
  JOHN 
  M. 
  CLARKE 
  

  

  The 
  list 
  of 
  Lower 
  Devonic 
  species 
  occurring 
  in 
  that 
  spectac- 
  

   ular 
  cliff 
  L'isle 
  percee 
  or 
  Perce 
  rock, 
  has 
  been 
  given 
  by 
  the 
  writer 
  

   with 
  some 
  degree 
  of 
  fulness 
  in 
  his 
  volume 
  on 
  the 
  geology 
  of 
  

   Gaspe 
  (N. 
  Y. 
  State 
  Mus. 
  Memoir 
  9, 
  part 
  1, 
  1908). 
  Among 
  these 
  

   species 
  several 
  trilobites 
  of 
  interest 
  have 
  been 
  described. 
  These 
  

   accounts 
  were 
  based 
  upon 
  the 
  collections 
  made 
  during 
  several 
  

   seasons 
  of 
  diligent 
  work, 
  and 
  subsequent 
  search 
  has 
  not 
  mate- 
  

   rially 
  added 
  to 
  the 
  census 
  of 
  the 
  fauna. 
  The 
  past 
  summer, 
  how- 
  

   ever, 
  brought 
  to 
  light 
  two 
  specimens 
  of 
  a 
  commanding 
  Homalo- 
  

   notus, 
  a 
  genus 
  not 
  hitherto 
  recorded 
  from 
  any 
  of 
  the 
  Devonic 
  

   outcrops 
  in 
  Gaspe 
  county, 
  and 
  not 
  only 
  its 
  presence 
  but 
  the 
  char- 
  

   acter 
  of 
  the 
  species 
  itself 
  is 
  worthy 
  of 
  note. 
  

  

  The 
  Homalonoti 
  of 
  the 
  boreal 
  Paleozoic 
  regions 
  in 
  America 
  

   are 
  distinctively 
  characterized 
  by 
  their 
  freedom 
  from 
  dermal 
  

   overgrowths. 
  They 
  carry 
  no 
  spines 
  or 
  tubercles 
  on 
  any 
  part 
  of 
  

   the 
  test. 
  This 
  is 
  a 
  statement 
  subject 
  of 
  course 
  to 
  the 
  limitations 
  

   of 
  our 
  pretty 
  considerable 
  knowledge 
  of 
  the 
  Paleozoic 
  faunas 
  on 
  

   this 
  continent 
  and 
  while 
  applicable 
  here, 
  it 
  can 
  not 
  be 
  so 
  broadly 
  

   stated 
  for 
  the 
  boreal 
  Palezoic, 
  particularly 
  Devonic, 
  Homalonoti 
  

   of 
  the 
  eastern 
  hemisphere. 
  There 
  are 
  European 
  species 
  of 
  which 
  

   the 
  Siluric 
  H. 
  k 
  n 
  i 
  g 
  h 
  t 
  i 
  and 
  the 
  Devonic 
  H. 
  armatus 
  are 
  

   leading 
  and 
  almost 
  sole 
  examples, 
  whose 
  test 
  is 
  spiniferous 
  or 
  

   tubercled, 
  while 
  the 
  predominant 
  species 
  are 
  devoid 
  of 
  these 
  

   growths 
  as 
  in 
  America. 
  

  

  The 
  armate 
  Homalonoti 
  are 
  on 
  the 
  whole 
  quite 
  distinctively 
  

   austral, 
  especially 
  in 
  their 
  Devonic 
  distribution. 
  Witness 
  of 
  this 
  

   is 
  the 
  great 
  abundance 
  of 
  H. 
  h 
  e 
  r 
  s 
  c 
  h 
  e 
  1 
  i 
  Murchison 
  in 
  the 
  

   South 
  African 
  Lower 
  Devonic 
  1 
  and 
  at 
  the 
  same 
  horizon 
  in 
  the 
  

   Falkland 
  islands. 
  

  

  There 
  is 
  an 
  abundant 
  and 
  often 
  beautifully 
  preserved 
  species 
  

   in 
  the 
  Lower 
  Devonic 
  shales 
  of 
  Sao 
  Paulo, 
  Brazil, 
  termed 
  by 
  the 
  

   writer 
  H. 
  n 
  o 
  t 
  i 
  c 
  u 
  s, 
  w 
  r 
  hich 
  is 
  free 
  of 
  spines 
  save 
  for 
  one 
  con- 
  

   spicuously 
  developed 
  on 
  the 
  epistoma, 
  a 
  structure 
  which 
  is 
  pres- 
  

   ent 
  in 
  H. 
  h 
  e 
  r 
  s 
  c 
  h 
  e 
  1 
  i, 
  but 
  absent 
  in 
  all 
  boreal 
  species. 
  

  

  1 
  The 
  large 
  number 
  of 
  species 
  of 
  this 
  genus 
  described 
  by 
  the 
  writers 
  on 
  

   the 
  South 
  African 
  Devonic 
  has 
  seemed 
  to 
  me 
  not 
  justified 
  by 
  evidence, 
  except 
  

   for 
  provisional 
  purposes. 
  

  

  138 
  

  

  