﻿Geology 
  and 
  Natural 
  History. 
  383 
  

  

  later 
  variously 
  modified 
  families. 
  The 
  series 
  from 
  Long 
  Island, 
  

   so 
  fully 
  and 
  thoroughly 
  described 
  by 
  Hollick 
  and 
  Jeffrey, 
  well 
  

   repays 
  study 
  in 
  this 
  connection. 
  So 
  too 
  the 
  far 
  older 
  and 
  widely 
  

   distributed 
  Xenoxylon. 
  

  

  Thirdly, 
  complicated 
  ray 
  structure 
  is 
  a 
  fairly 
  late 
  or 
  Creta- 
  

   ceous-Tertiary 
  feature 
  of 
  phanerogams. 
  To 
  name 
  almost 
  any 
  

   fossil 
  stem 
  is 
  to 
  cite 
  an 
  example 
  in 
  proof; 
  and 
  moreover, 
  those 
  

   simpler 
  coniferous 
  and 
  angiospermous 
  types 
  are 
  the 
  very 
  ones 
  

   which 
  have 
  mainly 
  suffered 
  extinction, 
  or 
  left 
  their 
  more 
  spe- 
  

   cialized 
  descendents. 
  

  

  Fourthly, 
  the 
  Magnolia-Liriodendropsis 
  complex 
  finds 
  its 
  

   great 
  expansion 
  in 
  the 
  lower 
  Cretaceous, 
  just 
  where 
  the 
  relative 
  

   abundance 
  as 
  fossils 
  indicates 
  the 
  culmination 
  of 
  the 
  conifers. 
  

   Thus 
  in 
  the 
  Comanchean 
  of 
  Kansas 
  there 
  are 
  two 
  dozen 
  charac- 
  

   teristic 
  leaf 
  types. 
  Of 
  compelling 
  interest 
  is 
  the 
  Liriodendron 
  

   series, 
  not 
  only 
  because 
  of 
  transitions 
  to 
  elliptiform 
  species, 
  but 
  

   exactly 
  because 
  Liriodendron 
  has 
  complex 
  wood 
  structure, 
  and 
  

   is 
  now 
  ditypic 
  (eastern 
  United 
  States, 
  China). 
  

  

  Of 
  course 
  all 
  ideas 
  of 
  stem 
  structure 
  in 
  the 
  Comanchean 
  and 
  

   Cretaceous 
  Magnolias 
  must 
  rest 
  on 
  inferences 
  like 
  those 
  cited. 
  

   But 
  it 
  would 
  leave 
  the 
  greater 
  question 
  in 
  a 
  very 
  sombre 
  light 
  

   indeed, 
  if 
  it 
  were 
  found 
  that 
  the 
  Liriodendron 
  assemblage 
  of 
  

   Comanchean 
  time 
  made 
  the 
  transition 
  toward 
  modern 
  types, 
  

   then 
  reverted, 
  and 
  suffered 
  extinction 
  anyhow. 
  It 
  is 
  rather 
  to 
  

   be 
  supposed 
  that 
  the 
  early 
  Magnolias 
  appear 
  abundant 
  exactly 
  

   because 
  generalized, 
  and 
  that 
  the 
  known 
  facts 
  cannot 
  be 
  ap- 
  

   pealed 
  to 
  as 
  an 
  instance 
  of 
  "reversible 
  evolution." 
  These 
  few 
  

   observations 
  on 
  a 
  many-sided 
  subject 
  at 
  least 
  tend 
  to 
  show 
  that 
  

   Liriodendron 
  retains 
  a 
  place 
  among 
  the 
  two 
  or 
  three 
  greatest 
  

   of 
  all 
  North 
  American 
  forest 
  trees, 
  a 
  place 
  like 
  that 
  of 
  the 
  red- 
  

   woods 
  among 
  conifers, 
  because 
  of 
  specialization. 
  "While 
  the 
  

   lesser 
  Drimys 
  befitting 
  a 
  great 
  range 
  from 
  Mexico 
  to 
  Tierra 
  del 
  

   Fuego, 
  is 
  older, 
  with 
  the 
  Trochodendron 
  wood 
  ancient. 
  

  

  2. 
  Illinois 
  Geological 
  Survey, 
  Frank 
  W. 
  De 
  Wolf, 
  Chief. 
  — 
  

   Bulletin 
  No. 
  37, 
  by 
  Gilbert 
  H. 
  Cady, 
  is 
  devoted 
  to 
  the 
  geology 
  

   and 
  mineral 
  resources 
  of 
  Hennepin 
  and 
  LaSalle 
  Quadrangles 
  ; 
  

   it 
  is 
  a 
  volume 
  of 
  136 
  pp. 
  illustrated 
  by 
  6 
  maps 
  and 
  36 
  text 
  

   figures 
  ; 
  the 
  work 
  has 
  been 
  done 
  in 
  connection 
  with 
  the 
  U. 
  S. 
  

   Geological 
  Survey. 
  The 
  area 
  lies 
  on 
  the 
  northern 
  edge 
  of 
  the 
  

   Illinois 
  Coal 
  Measures 
  ; 
  the 
  most 
  important 
  formations 
  are 
  the 
  

   Pennsylvanian, 
  in 
  which 
  coal 
  occurs 
  in 
  various 
  horizons, 
  the 
  

   LaSalle 
  coal 
  being 
  of 
  greater 
  persistence 
  and 
  the 
  only 
  one 
  now 
  

   being 
  mined. 
  

  

  Bulletin 
  No. 
  40 
  discusses 
  the 
  oil 
  investigations 
  made 
  in- 
  1917 
  

   and 
  1918. 
  It 
  is 
  stated 
  that 
  while 
  the 
  production 
  of 
  oil 
  is 
  second 
  

   only 
  to 
  that 
  of 
  coal, 
  the 
  fields 
  are 
  nevertheless 
  on 
  the 
  decline. 
  

   Some 
  hope 
  is 
  held 
  out 
  that 
  new 
  fields 
  may 
  be 
  discovered 
  and 
  

   better 
  methods 
  of 
  oil 
  extraction 
  may 
  be 
  developed. 
  

  

  3. 
  Minnesota 
  Geological 
  Survey, 
  William 
  H. 
  Emmons, 
  

  

  