﻿50 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  shaped 
  fishes 
  among 
  races 
  which 
  have 
  not 
  progressed, 
  the 
  origin 
  of 
  

   the 
  paired 
  fins 
  and 
  the 
  development 
  of 
  the 
  effective 
  fins. 
  The 
  chap- 
  

   ter 
  entitled 
  " 
  Geological 
  conclusions 
  " 
  is 
  of 
  special 
  interest 
  as 
  indicat- 
  

   ing 
  the 
  distribution 
  and 
  migrations 
  of 
  the 
  early 
  fish 
  fauna 
  and 
  may 
  

   well 
  be 
  reproduced 
  here. 
  

  

  GEOLOGICAL 
  CONCLUSIONS 
  

  

  It 
  will 
  be 
  convenient 
  to 
  include 
  under 
  this 
  head 
  certain 
  topics 
  

   whose 
  practical 
  bearing 
  is 
  of 
  chief 
  interest 
  to 
  the 
  geologist, 
  although 
  

   the 
  evidence 
  involved 
  is 
  partly 
  zoological, 
  and 
  in 
  still 
  larger 
  part 
  

   geographical, 
  or 
  paleogeographical. 
  We 
  refer 
  to 
  such 
  matters 
  as 
  

   relate 
  to 
  the 
  areal 
  and 
  vertical 
  distribution 
  of 
  Devonic 
  fish 
  life, 
  the 
  

   dispersion 
  of 
  new 
  types 
  and 
  varieties, 
  migration, 
  succession 
  and 
  

   occasional 
  recurrence 
  of 
  faunas, 
  and 
  indications 
  furnished 
  by 
  the 
  

   fossils 
  themselves 
  in 
  regard 
  to 
  climatal 
  and 
  physical 
  conditions, 
  

   either 
  those 
  of 
  local 
  nature, 
  or 
  others 
  prevailing 
  over 
  wide 
  areas. 
  

   Thus, 
  by 
  way 
  of 
  illustration, 
  we 
  are 
  able 
  to 
  affirm 
  from 
  the 
  general 
  

   complexion 
  of 
  ancient 
  faunas, 
  that 
  the 
  climate 
  of 
  arctic 
  regions 
  was 
  

   notably 
  warmer 
  during 
  the 
  Devonic 
  and 
  late 
  Paleozoic 
  than 
  at 
  sub- 
  

   sequent 
  periods. 
  We 
  are 
  in 
  possession, 
  also, 
  of 
  a 
  large 
  fund 
  of 
  

   evidence 
  regarding 
  migrational 
  movements, 
  and 
  can 
  delineate 
  with 
  

   great 
  exactitude 
  a 
  number 
  of 
  physical 
  barriers 
  that 
  were 
  interposed 
  

   to 
  lines 
  of 
  migration. 
  Means 
  are 
  at 
  hand 
  in 
  very 
  many 
  cases 
  for 
  

   distinguishing 
  between 
  free 
  swimming 
  inhabitants 
  of 
  the 
  open 
  sea 
  

   and 
  other 
  forms 
  whose 
  structural 
  organization 
  proves 
  them 
  to 
  have 
  

   been 
  bottom 
  feeders, 
  mud 
  grovelers, 
  or 
  frequenters 
  of 
  estuaries 
  and 
  

   fresh-water 
  lagoons. 
  Manifestly 
  inferences 
  of 
  this 
  nature 
  are 
  of 
  

   far-reaching 
  geological 
  significance, 
  besides 
  having 
  a 
  direct 
  practical 
  

   application. 
  Finally, 
  a 
  knowledge 
  of 
  the 
  relations 
  of 
  successive 
  

   vertebrate 
  faunas 
  is 
  an 
  important 
  corollary 
  to 
  the 
  information 
  we 
  

   have 
  concerning 
  fossil 
  invertebrate 
  faunas, 
  the 
  two 
  categories 
  being 
  

   mutually 
  complementary, 
  and 
  taken 
  altogether 
  are 
  essential 
  to 
  a 
  

   natural 
  classification 
  of 
  geologic 
  formations. 
  

  

  We 
  may 
  consider 
  first 
  some 
  of 
  the 
  more 
  general 
  conclusions 
  

   derived 
  from 
  a 
  study 
  of 
  the 
  distribution 
  of 
  Devonic 
  fishes, 
  having 
  

   special 
  reference 
  to 
  those 
  of 
  New 
  York 
  State. 
  In 
  the 
  first 
  place 
  it 
  

   is 
  necessary 
  to 
  bear 
  in 
  mind 
  that 
  the 
  Devonic 
  faunas 
  of 
  the 
  interior 
  

   of 
  North 
  America 
  announce 
  themselves 
  as 
  belonging 
  to 
  two 
  distinct 
  

   types, 
  one 
  being 
  more 
  or 
  less 
  confined 
  to 
  the 
  eastern, 
  and 
  the 
  other 
  

   to 
  the 
  west 
  central 
  United 
  States 
  and 
  Canada. 
  Or, 
  to 
  put 
  it 
  differ- 
  

   ently, 
  it 
  is 
  possible 
  to 
  recognize 
  within 
  the 
  interior 
  of 
  our 
  continent 
  

   two 
  more 
  or 
  less 
  distinct 
  geological 
  provinces 
  of 
  the 
  Devonic, 
  

   differing 
  from 
  each 
  other 
  and 
  from 
  the 
  more 
  remote 
  areas 
  lying 
  to 
  

   the 
  westward 
  (Cordilleran 
  and 
  continued 
  border 
  provinces) 
  in 
  

   their 
  respective 
  faunal 
  characteristics. 
  The 
  eastern 
  interior 
  prov- 
  

   ince, 
  which 
  has 
  received 
  the 
  name 
  of 
  Appalachian, 
  is 
  tvpically 
  

   represented 
  in 
  New 
  York 
  State, 
  but 
  extends 
  westward 
  into 
  Ontario 
  

   and 
  Michigan, 
  and 
  southwestward 
  into 
  the 
  Ohio 
  valley 
  region, 
  

  

  