﻿PREFACE 
  

  

  This 
  volume 
  has 
  been 
  prepared 
  and 
  will 
  be 
  published 
  under 
  the 
  

   provisions 
  of 
  an 
  act 
  of 
  the 
  Thirty-second 
  General 
  Assembly, 
  author- 
  

   izing 
  the 
  publication 
  of 
  Volume 
  7 
  of 
  the 
  Geological 
  Survey 
  of 
  Illinois, 
  

   approved 
  May 
  26, 
  1881. 
  

  

  The 
  first 
  section 
  of 
  the 
  volume 
  is 
  devoted 
  to 
  economical 
  geology, 
  

   and 
  mainly 
  to 
  a 
  record 
  of 
  the 
  development 
  of 
  the 
  coal 
  resources 
  of 
  

   the 
  State 
  since 
  the 
  publication 
  of 
  the 
  last 
  preceding 
  volume 
  in 
  1875. 
  

   The 
  mining 
  interests 
  of 
  the 
  State 
  are 
  now 
  second 
  only 
  in 
  import- 
  

   ance 
  to 
  those 
  of 
  agriculture, 
  and 
  although 
  the 
  information 
  obtainable 
  

   in 
  regard 
  to 
  many 
  of 
  the 
  experiments 
  made 
  with 
  the 
  drill, 
  as 
  well 
  

   as 
  that 
  to 
  be 
  derived 
  from 
  the 
  shafts 
  but 
  recently 
  sunk 
  within 
  the 
  

   borders 
  of 
  our 
  coal-producing 
  area, 
  has 
  in 
  many 
  cases 
  been 
  incom- 
  

   plete 
  and 
  unsatisfactory, 
  through 
  the 
  non-preservation 
  of 
  the 
  records 
  

   kept 
  by 
  those 
  having 
  the 
  work 
  in 
  charge, 
  yet 
  the 
  data 
  obtained, 
  

   although 
  by 
  no 
  means 
  as 
  complete 
  as 
  could 
  be 
  desired, 
  will, 
  I 
  

   trust, 
  prove 
  of 
  considerable 
  value, 
  and 
  tend 
  to 
  the 
  further 
  develop- 
  

   ment 
  of 
  this 
  important 
  industry. 
  

  

  Sections 
  two 
  and 
  three 
  are 
  devoted 
  to 
  the 
  description 
  and 
  illus- 
  

   tration 
  of 
  the 
  fossil 
  forms 
  belonging 
  to 
  the 
  Carboniferous 
  formation 
  

   of 
  the 
  Mississippi 
  valley, 
  and, 
  as 
  these 
  are 
  mostly 
  new 
  to 
  science, 
  

   their 
  publication 
  will 
  constitute 
  an 
  additional, 
  and, 
  I 
  trust, 
  an 
  

   acceptable 
  contribution 
  to 
  our 
  present 
  knowledge 
  of 
  the 
  specific 
  

   character 
  of 
  the 
  Carboniferous 
  fauna 
  of 
  the 
  North 
  American 
  conti- 
  

   nent. 
  

  

  In 
  our 
  work 
  on 
  the 
  vertebrates, 
  I 
  have 
  had 
  the 
  assistance 
  of 
  Mr. 
  

   Orestes 
  St. 
  John, 
  of 
  Topeka, 
  Kansas, 
  whose 
  familiar 
  acquaintance 
  

   with 
  the 
  fossil 
  fishes 
  of 
  the 
  palaeozoic 
  rocks 
  render 
  his 
  work 
  of 
  

   special 
  value 
  to 
  those 
  interested 
  in 
  this 
  department 
  of 
  palaeontology. 
  

  

  