﻿474: 
  Scientific 
  Intelligence. 
  

  

  groups 
  which 
  have 
  been 
  made 
  of 
  them, 
  are 
  altogether 
  artificial. 
  

   Not 
  only 
  do 
  they 
  run 
  the 
  one 
  into 
  the 
  other 
  in 
  a 
  gradual 
  manner, 
  

   but 
  the 
  same 
  individual 
  passes 
  successively 
  from 
  the 
  one 
  into 
  the 
  

   other 
  during 
  the 
  course 
  of 
  its 
  existence. 
  It 
  is 
  also 
  to 
  be 
  noted 
  

   that 
  they 
  are 
  not 
  restricted 
  (cantonnees) 
  to 
  any 
  particular 
  geo- 
  

   logical 
  horizon. 
  It 
  is 
  necessary 
  to 
  make 
  exception 
  in 
  the 
  case 
  of 
  

   the 
  Spirifers 
  with 
  extended 
  wings 
  of 
  Barvaux, 
  which 
  seem 
  to 
  be 
  

   peculiar 
  to 
  one 
  facies 
  of 
  the 
  Upper 
  Frasnien. 
  These 
  Spirifers 
  are 
  

   not 
  only 
  characterized 
  by 
  great 
  production 
  of 
  the 
  wings, 
  but 
  also 
  

   by 
  the 
  imbricated 
  scales 
  which 
  cover 
  their 
  plications, 
  forming 
  

   small 
  tubercles 
  on 
  the 
  surface. 
  Nevertheless, 
  although 
  this 
  pecu- 
  

   liarity 
  is 
  often 
  associated 
  with 
  the 
  enlargement 
  of 
  the 
  wings, 
  it 
  

   does 
  not 
  necessarily 
  accompany 
  it. 
  

  

  I 
  do 
  not 
  believe 
  therefore 
  that 
  there 
  are 
  varieties 
  in 
  the 
  species 
  

   called 
  Spirifer 
  verneuili, 
  but 
  rather 
  groups 
  of 
  forms. 
  These 
  

   groups 
  are 
  essentially 
  distinguished 
  from 
  zoological 
  varieties 
  

   because 
  the 
  same 
  individual 
  is 
  able 
  to 
  pass 
  successively 
  through 
  

   several 
  of 
  them 
  before 
  attaining 
  its 
  definitive 
  form. 
  

  

  It 
  is 
  in 
  the 
  upper 
  part 
  of 
  the 
  Frasnien, 
  i. 
  e. 
  in 
  the 
  middle 
  of 
  its 
  

   specific 
  duration, 
  that 
  the 
  Spirifer 
  verneuili 
  presents 
  the 
  widest 
  

   variations. 
  It 
  is 
  there, 
  where 
  in 
  some 
  sense 
  it 
  is 
  in 
  all 
  its 
  prime, 
  

   that 
  the 
  richness 
  of 
  form 
  is 
  added 
  to 
  abundance 
  of 
  numbers. 
  It 
  

   peopled 
  the 
  seas, 
  exceeding 
  in 
  numbers 
  all 
  the 
  other 
  fossils, 
  

   Atrypa 
  reticulatis 
  excepted. 
  However 
  none 
  of 
  these 
  forms 
  gave 
  

   birth 
  to 
  a 
  new 
  species, 
  not 
  even 
  to 
  a 
  constant 
  variety. 
  The 
  more 
  

   remarkable 
  forms 
  appeared 
  rather 
  as 
  local 
  varieties; 
  they 
  consti- 
  

   tuted 
  a 
  kind 
  of 
  tribe 
  or 
  physiological 
  family 
  having 
  its 
  circle 
  of 
  

   habitat, 
  but 
  which 
  did 
  not 
  propagate 
  itself 
  either 
  in 
  time 
  or 
  

   space. 
  The 
  lower 
  Famennien 
  is 
  already 
  less 
  rich 
  in^arieties 
  

   than 
  the 
  Frasnien. 
  When 
  we 
  rise 
  in 
  the 
  formation, 
  the 
  Spirifer 
  

   verneuili 
  presents 
  more 
  and 
  more 
  intermediate 
  characters. 
  It 
  

   becomes 
  extinct 
  finally 
  in 
  the 
  upper 
  Famennien 
  without 
  its 
  being 
  

   possible 
  to 
  admit 
  that 
  it 
  is 
  transformed 
  into 
  another 
  species. 
  

  

  Is 
  it 
  the 
  ancestor 
  of 
  Spirifer 
  attenuatus 
  and 
  of 
  Spirifers 
  of 
  the 
  

   group 
  of 
  Mosquensis 
  f 
  It 
  is 
  possible, 
  for 
  the 
  difference 
  between 
  

   the 
  two 
  types 
  is 
  not 
  extreme 
  ; 
  but 
  there 
  is 
  no 
  passage 
  from 
  the 
  

   one 
  to 
  the 
  other. 
  From 
  the 
  point 
  when 
  Spirifer 
  attenuatus 
  arises 
  

   it 
  assumes 
  immediately 
  its 
  distinctive 
  characters 
  : 
  all 
  the 
  ribs 
  of 
  

   the 
  wings 
  are 
  bifurcated. 
  But, 
  never, 
  from 
  the 
  lowest 
  beds 
  to 
  the 
  

   schists 
  of 
  Etrceungt 
  [the 
  uppermost 
  Devonian 
  horizon] 
  has 
  

   Spirifer 
  verneuili 
  shown 
  an 
  indication 
  of 
  bifurcation 
  of 
  the 
  ribs, 
  

   never, 
  spite 
  of 
  its 
  numerous 
  variations, 
  has 
  it 
  presented 
  a 
  tendency 
  

   to 
  pass 
  into 
  the 
  attenuatus 
  y 
  if 
  there 
  is 
  filiation 
  here, 
  the 
  trans- 
  

   formation 
  has 
  been 
  rapid 
  and 
  complete. 
  It 
  is 
  impossible 
  to 
  say 
  

   what 
  relation 
  there 
  is 
  between 
  Spirifer 
  verneuili 
  and 
  Spirifer 
  

   Orbelianus 
  and 
  aperturatus. 
  The 
  characters 
  which 
  distinguish 
  

   these 
  two 
  species 
  are 
  of 
  slight 
  importance 
  and 
  when 
  they 
  are 
  

   attenuated 
  they 
  become 
  almost 
  verneuili. 
  It 
  may 
  be 
  questioned 
  

   whether 
  they 
  ought 
  to 
  be 
  considered 
  as 
  species 
  or 
  only 
  simple 
  

   varieties, 
  the 
  passage 
  from 
  one 
  to 
  the 
  other 
  is 
  not 
  less 
  real 
  and 
  

  

  