Skip to main content

Full text of "Bulletin of the United States Geological Survey--The Correlation of Geological Faunas"

See other formats


3  1604  019  891  599 


I  I 


r  i 
5 1 


Bulletin  No.  210 


Series  C,  Systematic  Geology  and  Paleontology,  61 


DEPARTM  ENT  0  F  THE  [NTERIOK 
UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES  1).  WALCOTT,  DlBECTOB 


THE 


CORRELATION  OF  GEOLOGICAL  FAUNAS 


A  CONTRIBUTION  TO  DEVONIAN  PALEONTOLOGY 


BY 


HENRY    SHALER    WILLIAMS 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 

1  9  03 


V! 


Digitized  by  the  Internet  Archive 
in  2013 


http://archive.org/details/bulletinofunited210will 


CONTENTS 


Pane 

Introduction 5 

Chapter  I. — The  principles  of  correlation 10 

Importance  of  correlation : 10 

Correlation  division  of  the  United  States  Geological  Survey  .  10 

Dual  nomenclature ..... 11 

Definitions  and  nomenclature  of  f  aunal  paleontology . .  18 

Animal  and  plant  aggregates 13 

Zoological  and  botanical  classification 15 

Distribution  and  range 10 

Geological  faunas  and  their  nomenclature 20 

Nomenclature  of  formations 27 

Faunal  aggregates 28 

Chapter  II. — The  geological  expression  of  faunal  migrations.  _  33 

Migration  as  a  stimulus  to  variation  .  40 
Chapter  III. — Faunal   dissection  of   Middle  and  Upper  Devonian  of  the 

New  York  province 42 

Introduction  of  a  faunal  classification  of  the  Devonian  system. .  45 

Revised  classification  of  faunas 48 

The  statistics  and  the  plan  of  discussion 49 

Hamilton  formation  and  Tropidoleptus  carinatus  fauna 50 

Tropidoleptus  carinatus  fauna  of  eastern  counties  of  New  York 

and  Pennsylvania 51 

Distributional  values  of  the  species 52 

Frequency  values  of  the  species  .  _                                    52 

Range  values  of  the  species . 53 

Cayuga  Lake  section 54 

Eighteenmile  Creek  section  ...  5  '< 
Construction  of  a  standard  list  of  the  dominant  species  of  the  Tropido- 
leptus carinatus  fauna 58 

Effect  of  additional  statistics 02 

Statistics  based  on  analysis  of  the  zones  of  the  Livonia  salt  shaft.  08 

Hamilton  formation  in  Ontario,  Canada  _ .  04 

Hamilton  formation  in  Michigan 65 

Hamilton  formation  in  Wisconsin . 65 

Hamilton  formation  in  southern  Illinois  , . .  66 

Sellersburg  formation  in  Indiana 66 

Romney  formation  in  western  Maryland 07 

Absence  of  Tropidoleptus  fauna  in  other  regions 68 

Post-Hamilton  formations  and  their  faunas  in  New  York  province  68 

Fauna  of  eastern  extension  of  Portage  formation  71 
Fauna  of  Ithaca  formation  as  expressed  in  the  typical  locality  at 

Ithaca,  N.Y  73 

Productella  speciosa  fauna <  6 

Immigrant  species  of  Ithaca  formation  7S 

Mutation  and  correlation  of  the  faunas - 81 

3 


4  CONTENTS. 

Chapter  III — Continued.  Page. 

Chemung  formation  and  its  fauna       ... 82 

Spirifer  disjunctus  fauna 83 

Recurrence  of  the  Tropidoleptus  fauna  in  the  epoch  of  the  Spirifer  dis- 
junctus fauna . 89 

Marine  fauna  above  Oneonta  sandstone  of  eastern  New  York 92 

Chapter  IV. — Shifting  of  faunas 97 

Evidence  of  shifting  of  faunas  associated  with  deposition  of  Oneonta 

sandstone 97 

Principles  involved  in  shifting  of  geological  faunas 103 

Biological  consequences  of  shifting  of  faunas 105 

Effect  of  shifting  of  faunas  on  classification  of  geological  formations  . .  108 

Black  shale  sediments 109 

Portage  formation  sediments 110 

Fossiliferous  shaly  sediments  of  Ithaca  group 110 

Red  sandstone  sediments 110 

Faunal  shifting  and  correlation 112 

Chapter  V. — Equivalency  as  interpreted  by  geologists .  117 

Diversity  of  interpretation 117 

Correlation  of  Devonian  formation  of  Ohio,  western  New  York,  and 

eastern  New  York 120 

Chapter  VI. — The  bionic  value  of  fossils 124 

General  statement 124 

The  terms  ' '  species, ' *  ; '  race, ' '  and  ' '  generation  " .  _  _  127 

Order  of  magnitude  of  bionic  units . .__.'.  128 

Revised  definition  of  the  terms  ' '  fauna ' '  and  '  •  f aunule  " ' 131 

The  bionic  time  scale 132 

Bibliography 135 

Index 141 


I  I,  L  U  S  T  R  A  T  I  0  N. 


Plate  I.  Comparative  chart  of  the  Middle  and  Upper  Devonian  formations 

of  Ohio,  Pennsylvania,,  and  New  York 120 


THE  CORRELATION  OF  GEOLOGICAL  FAUNAS. 


By  Henry  Shaler  Williams. 


INTRODUCTION. 

In  the  year  1881  I  began  a  series  of  investigations  for  the  purpose 
of  discovering  the  laws  which  determine  the  association  of  fossils  in 
faunal  aggregates  and  their  modifications  in  relation  to  geographical 
distribution  and  to  vertical  succession,  in  order  to  apply  those  laws 
as  guides  to  the  correlation  and  classification  of  geological  formations. 
While  these  investigations  have  been  in  progress  many  other  workers 
have  joined  in  the  search.  Many  statistics  have  been  gathered,  and 
observations  have  been  extended  over  a  wide  field.  A  few  important 
results  have  been  attained,  and  the  nature  of  the  problem  is  now  more 
clearly  understood  than  at  the  outset.  It  seems,  therefore,  that  this 
is  a  fitting  time  to  review  the  progress  already  made,  and  to  point  out 
the  more  prominent  results  achieved  and  the  paths  along  which  future 
investigations  may  be  guided  with  most  promise  of  success. 

When  the  investigations  were  begun  it  was  already  known  that 
geological  formations  were  marked  by  species  of  fossils  differing 
greatly  for  each  succeeding  formation.  In  the  early  days  of  geology 
this  difference  was  supposed  to  be  due  to  extinction  of  old  and  the 
appearance  of  new  forms  for  the  first  time  with  the  income  of  each 
new  formation.  With  this  conception  was  associated  I  he  idea  of 
sharp  distinction  between  formations,  each  of  which  had  a  character- 
istic set  of  "  Leitfossilien."  The  prevalence  of  this  latter  view  domi- 
nated all  the  literature;  and  the  presence,  in  a  newly  exploited 
section  of  rocks,  of  a  species  supposed  to  be  characteristic  of  a  given 
formation  was  assumed  to  be  sufficient  evidence  of  the  presence  of 
the  formation  in  the  new  section.  On  this  basis  of  determination  it 
had  become  a  fact  that  under  the  name  of  each  formation  there  was 
catalogued  a  group  of  species  collected  from  widely  separated  regions 
and  found  in  different  kinds  of  rocks,  all  of  them  being  thus  lumped 
together  as  the  characteristic  species  of  the  formation  considered. 

At  the  outset  of  the  present  inquiry  it  was  evident  thai,  in  order  to 
learn  how  the  modification  of  species  lias  actually  taken   place,  the 


b  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

composition  of  the  fauna  of  a  formation  must  be  critically  examined, 
the  actual  association  of  species  in  each  bed  of  rock  must  be  analyzed, 
and  the  succession  of  species  traced  step  by  step  through  continuous 
sections. 

My  first  experiments  in  this  field  of  investigation  were  with  the 
faunas  exhibited  in  the  rocks  in  the  neighborhood  of  Ithaca,  N.  Y. 
In  these  rocks,  which  were  classified  as  Portage  and  Chemung,  a 
number  of  zones  filled  with  separate  faunules  a  were  discovered,  some 
of  which  were  entirely  different  from  others  in  the  series,  but  the 
order  of  their  succession  was  readily  distinguished  in  each  of  the 
rock  sections  for  miles  about.  This  integrity  of  the  faunules  in  geo- 
graphical distribution,  over  at  least  the  few  miles  of  area  at  first 
explored,  together  with  the  sharp  differences  in  the  composition  of 
successive  faunules,  suggested  a  clue  to  the  solution  of  the  larger 
problems  involved. 

When,  again,  on  comparison  of  two  sections  running  through  the 
same  portion  of  the  geological  column  it  was  found  that  a  forma- 
tion which  was  clearly  defined  in  one  section  was  missing  in  the  other, 
it  was  customary  (in  the  absence  of  evidence  of  unconformity)  to 
explain  the  absence  of  the  missing  member  in  the  second  section  by 
the  supposition  that  it  had  gradully  thinned  out  until  it  disappeared. 
Its  place  in  the  second  column  was  recognized,  but  the  thickness  of 
its  sediments  was  reduced  to  nothing  or  to  an  inappreciable  amount. 
Correlation  of  diverse  formations  being  made  on  this  basis,  the  gen- 
eral geological  column  was  constructed  of  a  single  series  of  superim- 
posed formations,  diversity  of  fossil  contents  standing  for  difference 
of  formations.  Each  formation  was  thus  forced  to  take  some  par- 
ticular place  in  a  single  geological  column. 

As  knowledge  of  the  faunas  increased,  the  failure  to  establish  the 
exact  identity  of  a  newly  discovered  fauna  with  any  of  the  faunas 
of  the  standard  column  already  described  led  to  the  intercalation  of 
the  formation  containing  it  between  the  standard  formations  whose 
faunas  most  closely  resembled  it.  That  there  might  be  living  at 
the  same  time  two  entirely  distinct  faunas  whose  records  were  buried 
and  preserved  within  a  few  miles  of  each  other  was  a  possibility  that 
was  not  then  seriously  contemplated.  I  refer  to  marine  faunas,  for 
the  distinction  between  marine,  fresh-water,  and  land  conditions  was 
clearly  recognized;  but  almost  never  were  faunas  from  diverse  envi- 

«  The  term  "faunule11  is  here  and  in  the  following  pages  used  to  distinguish  an  aggregate  of  fos- 
sils associated  in  a  single  stratum  or  zone  from  the  total  aggregate  of  species  (the  fauna)  dis- 
tributed through  a  greater  or  less  thickness  of  strata,  each  faunule  containing  a  considerable 
proportion  of  the  same  species,  but  not  always  in  the  same  combination  or  proportionate  abun- 
dance. The  association  in  the  faunule  is  supposed  to  be  an  expression  of  the  temporary  adjust- 
ment  to  environment  and  to  each  other  of  the  living  species— an  adjustment  determined  by  the 
relative  vigor  of  each  species;  whereas  the  fauna  is  an  aggregate  of  species  determined  by  sev- 
eral quite  divergent  conditions  and  factors,  the  fauna  living  on  so  long  as  these  conditions  and 
factors  remained  sufficiently  intact  to  permit  it  to  preserve  its  general  characteristics  and  the 
dominant  species  to  maintain  their  relative  place  in  the  fauna,  though  for  a  time  suffering  mor.e 
or  less  variation  of  composition,  due  to  local  and  temporary  conditions.     (See  page  131.) 


Wiixiams.]  INTRODUCTION.  7 

ronments  present  in  sections  so  nearly  contiguous  to  one  another  as 
to  occasion  confusion  in  correlation. 

The  case  of  the  Old  Red  sandstone  and  the  marine  Devonian  was  a 
conspicuous  exception  to  the  practice  indicated.  In  this  case  the 
marine  faunas  of  the  Devonian  limestone  were  recognized  by  Lonsdale 
as  holding  an  intermediate  place  between  the  Silurian  and  Carbonif- 
erous marine  faunas;  and  the  Old  Red  sandstones  were  known  to 
occupy  the  interval  between  these  two  systems ;  hence  the  equivalency 
of  a  series  of  marine  beds  with  a  series  of  estuaiy  or  fresh-water  beds 
containing  an  entirely  different  fauna  was  established.  But,  in  gen- 
eral, in  the  lesser  cases,  where  faunas  of  the  same  kind  of  organisms 
are  concerned,  it  has  been  the  prevailing  practice  of  geologists  every- 
where to  assume  that  formations  must  be  classified  in  a  single  column. 
Since  the  correlation  and  identification  of  formations  has  depended 
on  their  fossil  contents,  this  practice  has  resulted  virtually  in  the 
assumption  that  fossil  faunas  whose  identity  can  not  be  established 
must  be  either  older  or  younger  than  the  standard  faunas  to  which 
they  are  most  closely  related. 

It  was  in  the  belief  that  this  practice  was  erroneous  and  was  lead- 
ing to  false  conceptions  of  geological  history  that  the  investigations 
here  described  were  begun.  But  the  difficulties  in  the  way  of  demon- 
strating the  fallacy  of  the  practice  were  great.  Since  the  fossils  are 
the  only  means  by  which  the  identity  of  two  formations  found  at  a 
distance  from  each  other  can  be  established,  it  seemed  like  a  contra- 
diction to  say  that  two  formations  with  unlike  faunas  may  be  identi- 
cal in  age.  In  order  to  test  the  question,  it  was  necessary  to  take  a 
region  in  which,  for  considerable  distance,  the  structure  of  the  rocks 
was  so  simple  and  so  little  disturbed  that  the  stratigraphical  equiva- 
lency of  the  beds  could  be  traced  with  a  high  degree  of  certainty  from 
one  end  to  the  other,  independently  of  the  fossil  contents.  Such  a 
set  of  conditions  appeared  in  the  Devonian  rocks  of  New  York,  Penn- 
sylvania, and  eastern  Ohio.  It  was  proposed  to  make  a  series  of  sec- 
tions cutting  through  the  same  general  part  of  the  geological  column, 
at  intervals  of  about  50  miles,  extending  eastward  as  far  as  the  Hud- 
son River  Valley  and  westward  as  far  as  the  Cuyahoga  Valley  at 
Cleveland,  the  first  trial  section  having  been  made  along  the  meridian 
running  through  Ithaca,  N.  Y.,  in  1881-82.  Minute  st  udy  of  each  sec- 
tion was  to  be  made;  the  fossils  were  to  be  collected  from  each  fos- 
siliferous  zone,  the  position  of  which  was  to  be  carefully  noted,  and 
the  faunules  so  collected  were  to  be  separately  analyzed  and  listed. 
Intermediate  traverses  were  to  be  made  to  tie  together  the  sections 
by  clearly  recognized  continuous  strata,  so  that  the  stratigraphic 
equivalency  of  the  parts  of  each  section  could  be  established  with  cer- 
tainty. The  work  was  begun  privately  in  Cornell  University,  bu1  the 
necessity  of  transgressing  Stale  lines  led  to  the  association  of  the 
university  with  the  United  Slates  Geological  Survey,  by  whose  official 


8  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bum,,  mo. 

sanction  and  financial  assistance  the  necessarily  slow  process  of  accu- 
mulating the  statistics  lias  proceeded.  At  the  outset  Major  Powell, 
then  Director  of  the  Survey,  and  Mr.  Charles  T).  Walcott,  then  in 
charge  of  Paleozoic  paleontology,  gave  their  valued  encouragement. 
The  task  was  a  large  one,  but  its  importance  was  also  great.  A  sin- 
gle person  could  not  expect  in  a  lifetime  to  execute  the  whole  work 
required  to  solve  the  problem,  and  therefore  graduate  students  at  Cor- 
nell University,  and  later  at  Yale,  seeking  practice  in  geological  inves- 
tigation, were  interested  in  the  work,  and  original  research  along  these 
lines  was  intrusted  to  them.  A  large  amount  of  statistics  has  been 
thus  gathered. 

These  investigations  have  now  been  going  on  for  twenty  years,  and 
numerous  geologists  have  taken  part  in  them.  In  the  year  1885  a 
brief  report  of  the  general  results  attained  up  to  that  time  was  made 
before  the  American  Association  for  the  Advancement  of  Sciences 
At  that  time  ten  of  the  sections  had  been  run,  viz:  Cuyahoga,  Ohio; 
Painesville,  Ohio;  Girard,  Pennsylvania;  Chautauqua,  New  York- 
Pennsylvania;  Genesee,  New  York-Pennsylvania;  Canandaigua,  New 
York;  Cayuga,  New  York;  Tioughnioga,  New  York;  Chenango,  New 
York;  Unadilla,  New  York.  The  fossils  were  collected  from  the 
separate  faunules,  and  certain  general  conclusions  were  then  evident. 
Since  then  Messrs.  Prosser,  Clarke,  Darton,  and  others  have  pushed 
the  sections  farther  east,  and  they  have  been  extended,  with  the  aid 
of  Messrs.  Van  Ingen,  Weller,  and  Kindle,  into  Missouri,  Arkansas, 
Kentucky,  Indiana,  Virginia,  and  West  Virginia.  Messrs.  Geiger  and 
Sayles  have  added  collections  from  the  Appalachian  region.  The 
Maryland  geological  survey  is  adding  to  the  statistics  for  Maryland, 
and  investigations  are  now  going  on  in  many  other  regions  of  the 
United  States.  Preliminary  study  of  most  of  the  collections  has  been 
made.  The  investigations  for  some  pail  of  the  field  have  been  car- 
ried much  further  than  others,  but  the  undertaking  has  now  reached 
a  stage  in  which  it  is  possible  to  exhibit  the  general  bearings  of  the 
results  upon  the  whole  field  of  stratigraphical  geology  and  to  state  the 
principles  upon  which  the  investigations  have  proceeded,  as  well  as  to 
suggest  at  least  what  may  be  expected  in  the  future,  when  the  facts 
shall  be  fully  elaborated. 

In  the  preparation  of  this  report  I  have  been  obliged  to  refer  often 
to  the  statistics  already  gathered.  Some  of  them,  accumulated  by 
myself  or  under  my  direction,  have  been  published.  Other  statistics, 
in  the  form  of  unpublished  notes,  compiled  in  the  course  of  elabora- 
ting the  collections,  have  also  been  freely  consulted.  In  addition  to 
these  sources,  the  reports  of  others  working  in  the  same  field  have 
been  used,  and  for  all  such  statistics  I  am  deeply  grateful  to  the 
contributing  authors.     The   bibliographic  list  is  large,  and  may   be 


"( >n  the  classification  of  the  Upper  Devonian:  Proc.  Am.  Assoc  Adv.  Sci.,  Vol.  XXXIV.  L886, 
pp.  222-234. 


Williams.]  INTRODUCTION.  9 

referred  to  for  the  names  of  those  to  whom  I  am  chiefly  so  indebted. 
Works  not  mentioned  in  that  list,  such  as  standard  reports  on  the 
paleontology  of  groups  and  State  and  Government  reports  on  the 
geology  and  paleontology  have  also  been  consulted  for  such  facts  as 
bear  upon  the  questions  discussed.  I  wish  also  to  acknowledge  my 
indebtedness,  on  the  theoretical  side  of  the  subject,  to  the  suggestions 
of  others,  though  the  influence  of  these  may  not  always  be  directly 
traceable.  Barrande's  theory  of  colonies ;  Newberry's  theory  of  cycles 
of  sedimentation ;  the  principle  of  separate  facies  for  each  formation 
elaborated  by  Renevier;  Chamberlin's  theories  regarding  the  relation- 
ship of  restriction  of  faunal  occupation  of  sea-bottom  to  continental 
oscillation  and  the  base-leveling  of  continents — these  have  all  been 
taken  in  and  digested  in  elaborating  the  hypotheses  here  advanced. 
Finally,  with  high  appreciation  of  valuable  assistance  rendered,  I 
wish  to  acknowledge  my  special  indebtedness  to  Messrs.  Prosser, 
Harris,  Van  Ingen,  Weller,  Kindle,  and  Cleland,  who,  as  graduate 
students  at  Cornell  and  Yale,  have  entered  with  enthusiasm  into  the 
investigations,  and  who  are  still  engaged  in  prosecuting  them  with 
vigor  and  success  in  different  parts  of  the  field. 


CHAPTER   I. 
THE   PRINCIPLES   OF   CORRELATION. 

IMPORTANCE    OF    CORRELATION. 

In  the  Ninth  Annual  Report  of  the  United  States  Geological  Survey 
(1889),  the  Director  called  attention  to  the  importance  of  correlation 
in  the  work  of  the  Survey.     His  words  are: 

In  order  to  develop  the  geological  history  of  the  United  States  as  a  consistent 
whole,  it  is  necessary  to  correlate  the  various  local  elements.  .  .  It  is  especially 
important  to  determine  the  synchrony  of  deposits.  So  far  as  the  outcrops  of  strata 
can  be  continuously  traced,  or  can  be  observed  at  short  intervals,  correlation  can 
be  effected  by  the  study  of  stratigraphy  alone.  The  correlation  of  strata  sepa- 
rated by  wide  intervals  of  discontinuity  can  be  effected  only  through  the  study  of 
their  contained  fossils.  This  is  not  always  easy,  and  it  is  now  generally  recog- 
nized that  it  is  possible  only  within  restricted  limits.  As  distance  increases  the 
refinement  in  detail  of  correlation  diminishes. 

Recent  discussions  in  connection  with  the  work  of  the  International  Congress 
of  Geologists  have  shown  that  different  students  assign  different  limits  to  the  pos- 
sibilities of  correlation  and  give  different  weights  to  the  various  kinds  of  paleon- 
tologic  evidence  employed. 

The  study  of  the  data  and  principles  of  correlation  is  thus  seen  to  be  a  necessary 
part  of  the  work  of  the  Geological  Survey/' 

CORRELATION   DIVISION   OF  THE  U.  S.  GEOLOGICAL  SURVEY. 

A  division  of  the  Survey  was  thereupon  established  for  the  purpose 
of  preparing  essays  on  correlation,  and  summarizing  existing  knowl- 
edge bearing  on  the  correlation  of  American  strata.  A  number  of 
essays  were  subsequently  prepared  by  specialists  and  published  as 
bulletins  of  the  Survey.     Those  now  published  are  as  follows: 

No.  80.  Devonian  and  Carboniferous,  H.  S.  Williams,  1891. 

No.  81.  Cambrian,  C.  D.  Walcott,  1891. 

No.  82.  Cretaceous,  C.  A.  White.  1891. 

No.  83.  Eocene,  W.  B.  Clark,  1891. 

No.  84.  Neocene,  Dall  and  Harris,  1892. 

No.  85.  Newark,  I.  C.  Russell,  1892. 

No.  86.  Archean  and  Algonkian,  C.  R.  Van  Hise,  1892. 

This  attempt  to  bring  together  the  facts  available  for  the  correla- 
tion of  American  formations  was  a  direct  consequence  of  the  work  of 
the  International  Congress  of  Geologists,  and  particularly  of  the 
American  committee  of  the  congress  whose  report  was  made  to  the 
London  session  of  the  congress  in  the  year  1888. 


"Ninth  Ann.  Rept.  U.  S.  Geol.  Survey,  1889,  p.  10. 
10 


Williams.]  PRINCIPLES    OF    CORRELATION.  11 

DUAL   NOMENCLATURE. 

It  was  while  acting  as  a  member  of  the  American  com  initio,,  which 
was  engaged  in  preparing  reports  on  the  American  systems  for  the 
International  Congress  that  I  became  impressed  with  the  necessity  of 
a  dual  nomenclature.  The  common  usage  abroad,  as  here,  was  to 
name  and  classify  geological  formations  only.  Fossils  were  a  means 
of  their  identification,  but  no  attempt  had  been  made  to  distinguish 
the  limits  of  the  life  range  of  the  fossil  faunas  from  the  formation al 
boundaries  which  were  established  on  lithological  and  stratigraphica] 
grounds. 

The  principle  of  distinguishing  the  faunal  from  the  formational 
classification  and  nomenclature  was  thus  summarized  in  the  Compte 
Rendu  of  the  Fourth  Congress. 

Prof.  H.  S.  Williams  at  the  Albany  meeting  [1887]  suggested  an  important 
fundamental  idea,  and  one  which  may  influence  materially  the  final  distribution 
of  terms  in  stratigraphic  nomenclature,  viz,  the  adoption  of  a  dual  set  of  designa- 
tions—one  set,  that  referring  to  the  lithological  character  of  the  rock  masses  and 
based  on  geographic  names,  will  be  liable  to  vary  as  the  strata  change  from  place 
to  place:  and  the  other,  based  on  some  great  and  persistent  life  characters,  shall 
refer  to  the  faunas  of  those  rock  masses  and  be  substantially  constant  over  large 
areas,  and  perhaps  over  the  world.  It  is  very  evident  that  great  confusion  has 
resulted  in  the  past,  among  geologists,  by  confounding  these  distinctions,  and 
much  controversy  has  arisen  in  attempting  to  maintain  one  or  the  other  of  these 
different  zonal  designations.  Stratigraphic  work  has  been  ignored,  or  at  least 
neglected,  by  paleontologists,  and  the  practical  field  geologist  has  been  tempted, 
in  some  instances,  to  ignore,  if  not  to  deny,  the  assertions  of  the  paleontologist. 
Instead  of  this  confusion  there  should  be  introduced  some  new  departure.  The 
confusion  results  from  a  confusion  of  nomenclature.  Faunal  characters  have 
been  made  to  have  the  force  and  the  usage  of  stratigraphic  designations  and  have 
been  extended  as  stratigraphic  features  over  strata  where  the  faunal  characters 
are  wanting.  Again,  stratigraphy,  based  on  natural  and  great  lithological  dis- 
tinctions, having  been  defined  in  one  region  by  its  faunal  associations,  is  extended 
over  other  States  by  one  geologist  so  far  as  he  finds  the  lithology  to  warrant,  and 
by  another  so  far  as  he  finds  the  paleontology  to  warrant. 

There  are,  hence,  two  laws  by  which  we  must  be  governed  in  framing  a  scheme 
of  nomenclature  which  shall  allow  the  freest  rein  both  to  the  stratigraphic  geolo- 
gist and  to  the  paleontologist.  One  relates  to  the  work  of  the  stratigrapher,  who 
takes  account  of  the  great  physical  changes  to  which  the  earth's  surface  has  been 
subjected,  and  the  other  refers  to  the  work  of  the  paleontologist,  who  strives  to 
delineate  the  organic  changes  which  the  surface  of  the  earth  has  witnessed. 
These  changes  have  been  supposed  to  be  coeval  and  coextensive:  but  our  investi- 
gations show  they  have  not  been  so  entirely.  But  we  sometimes  have  the  same 
fauna,  or  nearly  the  same,  living  under  different  circumstances,  and.  perhaps, 
also  at  different  dates,  in  different  parts  of  the  world. 

So  long  as  the  geology  of  the  United  States,  for  instance,  was  known  accurately 
in  only  one  part  (New  York  State)  the  faunal  characters  which  the  formations 
were  found  to  exhibit  were  seen  to  be  coincident  with  the  si  ratigraphic  fcosogreal 
an  extent  that  there  was  no  reason  to  dissociate  them  under  separate  schemes; 
but  since  the  whole  area  of  the  United  States  is  being  brought  under  careful 
examination,  it  is  found  that  the  close  connection  which  these  two  classes  of 
characters  have  in  New  York  State  is  broken  up  and  they  begin  to  diverge  grad 


12  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bum.  210. 

ually  in  various  places  and  in  different  ways.  The  same  experience  is  found,  to  a 
greater  or  less  extent,  as  any  local  terms  are  extended  from  any  of  the  States  into 
those  contiguous.  This  plainly  shows  that  unless  there  he  allowed  great  freedom 
to  vary  from  the  scheme  adopted  for  stratigraphic  designations,  any  nomenclature 
which  the  committee  or  the  International  Congress  may  adopt  will  he  but  a  short- 
lived experiment. 

It  will  obviate  all  this  confusion  if  *  *  *  one  set  of  names  be  chosen  for  the 
lithological  characters  and  another  for  the  faunal. 

The  stratigraphic  terms  should  be  wholly  geographic  and  should  be  allowed  to 
change  as  often  as  local  geologists  deem  it  is  necessary.  The  faunal  terms  should 
be  very  broad  in  their  scope  at  the  outset,  and  subdivisions  should  be  introduced 
as  fast  as  the  special  subfaunas  are  discovered  and  defined." 

This  was  stated  more  explicitly  in  a  paper  published  in  1894.* 

As  surveys  have  advanced,  and  as  the  field  of  geological  correlation 
has  gone  beyond  local  and  national  boundaries,  the  task  of  establish- 
ing correlations  has  made  the  necessity  of  a  dual  nomenclature 
more  imperative.  Correlations  between  widely  separated  regions  are 
now  established  on  the  basis  of  fossils  alone.  Correlations  on  the 
basis  of  continuity  of  lithological  peculiarities  are  already  known  to  be 
valid  for  only  limited  areas.  Thus  geologists  throughout  the  world 
are  already  adopting  the  principle  of  a  dual  method  of  correlation, 
although  the  nomenclature  and  classification  of  correlation  are  still 
primarily  conjoined  with  lithological  formations,  the  names  of  which 
furnish  the  only  means  of  distinguishing  the  faunas  and  floras  which 
they  contain. 

This  lack  of  a  nomenclature  by  which  to  distinguish  the  lithologic- 
ally  defined  formation  from  the  biologically  defined  fauna  (which 
may  or  may  not  be  limited  in  its  range  by  the  boundaries  of  the  for- 
mation) can  be  supplied  only  through  discrimination  of  the  charac- 
teristics of  actual  fossil  faunas  and  a  demonstration  of  their 
independence  of  the  limiting  conditions  by  which  the  formations  are 
defined.  If  it  can  be  shown  that  fossil  faunas  and  floras  can  be  dis- 
criminated, defined,  and  discussed  separately  from  the  formations, 
which  now  constitute  the  only  elements  of  geological  classification, 
not  only  will  the  separate  nomenclature  naturally  follow,  but  the  fos- 
sil fauna  will  then  become,  as  it  is  now  partially  recognized  to  be,  the 
definite  means  of  determining  the  time  relations  of  geological  for- 
mations.    Such  a  discrimination  is  attempted  in  the  following  pages. 

In  order  to  exhibit  the  characteristics  of  faunas  a  concrete  case  is 
selected  from  among  the  faunas  of  the  Devonian  system,  the  choice 
having  been  determined  by  the  abundance  of  the  facts  already  gath- 
ered regarding  Devonian  faunas.  Abundance  of  fossils,  frequency  of 
exposures,  and  wideness  of  distribution  distinguish  the  Hamilton 
formation  of  the  New  York  section  above  all  other  formations  in  the 
country.  The  large  number  of  workers,  the  degree  of  refinement  in 
analysis,  and  the  fullness  of  publication  of  the  statistics  regarding 


aCompte  Rendu  Congres  Geologique  International,  fourth  session,  1888,  A  91. 

bOn  dual  nomenclature  in  geological  classification,  by  H.  S.  Williams:  Jour.  G-eol.,  Vol.  II,  p.  145. 


Williams.]  PRINCIPLES    OF    CORRELATION.  13 

the  Hamilton  formation  have  made  it  possible  to  treat  the  facts  con- 
cerning it  with  a  degree  of  precision  that  would  not  be  possible  in  con- 
sidering a  formation  which  is  less  perfectly  known  or  one  the  facts 
concerning  which  are  scattered  and  but  imperfectly  classified. 

For  the  discussion  of  a  geological  fauna  it  is  also  important  to  have 
some  conception  of  the  environmental  conditions  under  which  it  lived 
and  the  succession  of  conditions  which  have  preceded  and  led  up  to 
them.  Thus,  to  understand  the  fossil  fauna  preserved  in  the  Hamil- 
ton formation,  it  is  needful  to  reconstruct  the  physical  conditions  of 
the  Devonian  sea  in  which  the  fauna  lived,  and  to  look  backward 
over  the  history  of  that  sea  for  some  considerable  period  of  geological 
time.  In  order  to  describe  a  fossil  fauna  it  must  be  traced  back  to  a 
time  when  it  was  not,  and  onward  till  it  has  ceased,  and  thus  the  his- 
tory of  the  basin  in  which  the  evolution  has  taken  place  is  incidental 
to  the  description  of  the  fauna  itself. 

DEFINITIONS  AND  NOMENCLATURE  OF  FAUNAL  PALEONTOLOGY. 

The  primary  fact  that  fossils  may  be  used  in  identifying  formations 
and  tracing  them  from  place  to  place  was  announced  and  demonstrated 
by  William  Smith.  Many  other  laws  regarding  the  order  and  suc- 
cession of  fossils  have  been  formulated  by  d'Archiac,  Bronn,  Pictet, 
Lyell,  Brongniart,  Zittel,  and  other  writers  on  paleontology.  But  in 
addition  to  these  fundamental  and  established  laws  of  the  relations  of 
fossils  to  formations,  there  are  some  special  facts  or  principles  per- 
taining to  the  relations  which  living  organisms  bear  to  their  environ- 
ment and  to  each  other,  brought  out  by  the  study  of  organic  evolution, 
which  require  definitions  and  lead  to  the  adoption  of  terms  differing 
somewhat  from  those  in  common  use,  at  least  with  special  application 
to  correlation  and  the  expression  of  time  relations  in  geology. 

The  question  here  raised  is  not,  Can  geologic  formations  be  corre- 
lated by  their  contained  fossils?  The  fact  of  correlation  is  taken  for 
granted;  but  the  questions  are,  Wherein  does  correlation  consist? 
Wrhat  is  done  in  correlation?  Upon  what  principle  are  correlations 
made? 

Thus  the  discriminations  to  be  made  pertain  to  the  relations  which 
fossils  bear  to  one  another,  to  the  geological  conditions  of  preserva- 
tion, to  the  conditions  of  their  living  and  continuing  to  live  in  the 
past,  and,  finally,  to  the  value  of  fossils  as  means  of  distinguishing 
different  periods  of  geological  time  as  well  as  of  identifying  like  periods 
of  time  represented  by  them. 

ANIMAL  AND  PLANT  AGGREGATES. 

To  discuss  organisms  in  their  relations  to  time,  it  becomes  necessary 
to  treat  of  them  in  aggregates  and  to  discriminate  the  reasons  for 
which  the  particular  aggregations  are  made. 

The  zoologist  associates  organisms  on  the  basis  of  their  morpholog- 
ical affinities,  and  calls  the  aggregates  species,  genera,  orders,  etc.    Two 


14  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

specimens  belong  to  the  same  species  because  the  morphological  char- 
acters which  the  zoologist  regards  as  of  specific  rank  are  alike  in  the 
two  specimens.  The  members  of  the .  same  order  are  thus  classified 
together  because  they  exhibit  the  same  ordinal  characters.  The 
members  of  the  same  species  were  formally  supposed  to  be  so  asso- 
ciated because  of  their  genetic  affinity — i.  e.,  descent  from  common 
parents;  but  we  are  now  accustomed  to  recognize  community  of  char- 
acters, of  whatever  rank,  as  an  indication  of  the  genetic  affinity  of  the 
organisms  exhibiting  them.  The  difference  between  ordinal  affinity 
and  specific  affinity  is  one  of  degree,  not  of  kind ;  the  members  of  the 
same  order  are  genetically  related,  but  the  relationship  is  more  distant 
than  that  of  members  of  the  same  species.  Thus  the  terms  species, 
genus,  order,  and  class  are  applied  to  aggregates  of  plants  and  animals 
on  the  basis  of  their  genetic  affinity,  and  the  several  terms  indicate 
the  degree  of  nearness  of  affinit}^.  The  individuals  associated  to  form 
a  particular  aggregate  of  this  kind  may  be  fossils  or  living  beings, 
and  they  may  come  from  opposite  sides  of  the  earth,  but  they  are 
associated  on  the  basis  of  the  likeness  of  the  morphological  characters 
they  possess,  and  they  are  classified  on  the  basis  of  the  theoretical 
relative  degrees  of  kinship  they  bear  to  one  another.  A  species  or  a 
genus  is  therefore  an  ideal  aggregate.  No  one  ever  sees  the  whole  of 
a  species,  and  only  as  its  relationship  to  place  and  time  are  indicated 
can  the  aggregate  called  a  species  be  defined.  Furthermore,  the  terms 
species,  genus,  etc.,  are  arbitrarily  applied  in  every  particular  case. 
In  other  words,  there  is  no  standard  except  common  practice  to  deter- 
mine what  characters  are  of  varietal,  specific,  or  generic  rank.  But 
the  law  is  well  established  that  the  aggregate  shall  be  named  in  the 
order  of  degree  of  affinity  by  the  terms  species,  genus,  family,  order, 
class,  etc. ,  terms  implying,  progressively,  near  to  more  distant  kinship. 

A  second  mode  of  classifying  organic  aggregates  is  on  the  basis  of 
their  relationship  to  environment,  or  to  the  conditions  of  life.  Thus 
we  find  Walther,  in  his  "Bionomie  desMeeres"  (1873),  adopting  and 
applying  Haeckel's  terms:  Halobios,  the  total  aggregate  of  living 
beings  inhabiting  the  sea,  as  distinguished  from  Limnobios,  the 
inhabitants  of  fresh  water,  and  from  Geobios,  the  organisms  inhab^ 
iting  the  land.  The  marine  organisms  (Halobios)  are  subdivided 
into  Benthos,  those  living  on  the  bottom,  as  distinguished  from  Necton 
and  Plankton,  the  inhabitants  of  the  open  seas.  Depth  of  range  of 
faunas  or  floras  is  indicated  by  such  terms  as  littoral  or  abyssal.  Such 
aggregates  are  made  without  consideration  of  genetic  affinity  or  like- 
ness of  form;  all  kinds  of  animals  and  plants  living  together  are 
included.  The  general  basis  of  the  classification  is  coincident  with 
area  of  geographical  distribution,  and  the  relationship  determining 
the  classification  is  the  adaptation  of  the  organisms  to  the  common 
conditions  of  environment. 

A  third  kind  of  aggregates  of  organisms  is  defined  by  the  geologist 


Williams]  ANIMAL    AND   PLANT    AGGREGATES.  15 

lie  speaks  of  Paleozoic  faunas,  Carboniferous  floras,  the  fauna  of  the 
Trenton  or  of  the  Cambrian  or  of  the  Eocene.  The  basis  of  aggrega- 
tion in  these  cases  is  the  fact  of  living  at  the  same  time,  or  period  of 
time,  in  the  earth's  history;  or,  to  speak  more  abstractly,  the  geolog- 
ical range  of  the  organisms.  The  Eocene  fauna  includes  all  the  ani- 
mals, of  whatever  descent  or  of  whatever  zoological  rank,  existing  in 
all  kinds  of  environments,  of  which  fossil  remains  are  known  occurring 
in  the  Eocene  formations  of  the  whole  world.  As  at  present  defined  the 
term  Eocene  is  applied  to  formations  of  ditferentlithological  kinds,  out- 
cropping in  various  parts  of  the  world,  the  only  final  test  of  the  Eocene 
age  of  which  is  the  uniformity  of  the  faunas.  Hence  it  is  evident  that 
the  assumption  is  made  that  the  whole  life  of  the  globe  for  each  period 
of  time  is  in  a  marked  degree  alike  for  like  conditions  of  environ- 
ment. But  this  conclusion  is  true  only  when  the  qualifying  phrase 
in  a  marked  degree  is  kept  in  mind,  for  a  comparison  of  the  faunas 
and  floras  from  different  parts  of  the  earth  now  living  shows  them  to 
differ,  though  living  under  like  conditions  of  environment. 

Students  of  geographical  distribution  have  shown  that  in  distant 
parts  of  the  same  ocean  the  species  are  widely  divergent,  as  much 
difference  existing  between  the  marine  faunas  of  the  southern  and 
northern  temperate  zones  as  between  the  faunas  of  two  successive  for- 
mations of  a  continuous  geological  section.  It  is  evident  from  this 
observation  that  discussions  of  the  time  relations  of  fossils  must  treat 
not  only  of  the  genetic  affinity  of  the  forms  making  up  a  fauna,  but 
of  the  geographical  distribution  and  of  the  geological  range  of  the 
species  concerned. 

While  species,  genus,  etc.,  have  been  adopted  as  terms  to  express 
genetic  affinity  of  the  organic  aggregates  under  consideration,  fauna 
and  flora  are  general  terms  used  to  indicate  aggregates  of  animals  or 
plants  associated  on  the  basis  of  their  geographical  distribution  (or 
adaptation  to  similar  conditions  of  environment)  and  their  geological 
range  (or  place  in  the  evolutional  history  of  the  total  life  of  the  globe). 
It  is  no  longer  internal  structure  but  external  conditions  which 
determine  these  latter  aggregations 

In  discussing  fossil  aggregates  of  organisms  we  have  to  consider, 
therefore,  this  threefold  relationship  they  bear,  viz,  (a)  to  zoological 
and  botanical  classification,  (b)  to  geographical  distribution,  and  (c) 
to  geological  range. 

ZOOLOGICAL   AND   BOTANICAL    CLASSIFICATION. 

The  first  kind  of  relationship  is  expressed  by  the  internal  structure 
possessed  by  the  organisms  themselves;  hence  the  definition  of  an 
aggregate  of  this  kind  is  in  terms  of  morphological  characters,  and 
its  classification  is  based  upon  the  rank  (the  taxonomic  rank)  of  these 
characters,  which  is  indicated  by  the  technical  name  of  the  species  or 
genus  or  order  to  which  the  individual  organism  is  said  to  belong. 


16  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

What  is  actually  meant  in  such  classification  is  that  the  individual 
specimen  to  which  a  particular  specific  name  is  applied  exhibits  in  its 
morphological  structure  the  characters  which  have  been  described 
under  the  specific  name  used.  In  the  same  way,  to  say  that  a  certain 
animal  or  plant  belongs  to  a  particular  genus  means  that  it  possesses 
the  characters  to  which  the  generic  name  used  has  been  scientifically 
applied. 

The  specific  and  generic  name  given  to  a  fossil  applies  to  the  peculiar 
morphological  characters  recognized  in  the  scientific  definition  of  the 
species  or  genus,  and  in  giving  it  we  are  not  dealing  with  the  individ- 
ual as  a  whole  or  with  aggregates  of  individuals,  but  only  with  the 
particular  characters  exhibited  by  the  individuals  implied  by  the 
name.  When,  for  instance,  it  is  stated  that  Phacops  bufo  lived  as 
long  as  a  third  of  the  time  represented  by  the  Devonian  system,  it  is 
not  meant  that  any  individual  specimen  continued  to  live  so  long,  but 
that  in  genetic  succession  the  specific  characters  of  the  species  Phacops 
bufo  were  repeated  without  noticeable  and  permanent  modifications 
during  that  period  of  time.  We  are  not  dealing  with  the  biological 
aggregate,  a  taxonomic  species,  but  with  the  geological  aggregate,  a 
living  succession  of  individuals — the  race. 

The  terms  of  zoological  and  botanical  classification  are  constructed, 
primarily,  to  apply  to  living  organisms — animals  and  plants.  A  fauna 
has  thus  come  to  mean,  in  scientific  usage,  an  aggregate  of  animals 
of  different  kinds  structurally,  associated  on  the  basis  of  somo  condi- 
tions existing  outside  the  animals  themselves.  These  conditions  may 
be  kind  of  element,  as  air,  water,  or  land  inhabited;  place,  as  coun- 
try, mountain,  sea;  altitude,  as  plain,  plateau,  or  mountain,  or  zones 
of  depth  in  water,  or  geological  formation,  or  kind  of  sediments  in 
which  the  remains  are  preserved  as  fossils.  Flora  is  a  term  for  the 
aggregate  of  plants  under  like  conditions. 

DISTRIBUTION   AND   RANGE. 

When  the  conditions  determining  the  classification  of  the  fauna  or 
flora  are  geographical,  the  boundaries  and  their  measurement  are 
spoken  of  as  geographical  distribution.  Thus  the  fauna  is  said  to  be 
distributed  over  a  country  or  through  a  number  of  degrees  of  latitude^ 
or  through  a  number  of  feet  in  altitude  above  the  sea,  or  through  a 
number  of  fathoms  of  depth  below  sea  surface.  Geographical  distri- 
bution is  concerned  with  the  relation  of  organisms  in  faunal  or  floral 
aggregates  to  the  position  of  their  living,  if  living  forms,  or  of  their 
burial  if  fossils. 

Range  and  geological  range  are  terms  which  signif y  that  the  criterion 
of  association  is  geological  rather  than  geographical,  and  refer  to  the 
association  of  organisms  with  geological  formations.  Thus  a  genus  is 
said  to  range  from  the  Cambrian  to  the  Devonian  systems;  or  the 
geological  range  of  a  species  or  fauna  may  be  said  to  extend  from  one 


Williams]  ANIMAL    AND    PLANT    AGGREGATES.  17 

formation  to  another.  This  use  of  the  term  range  is  illustrated  by 
the  phrase  "Atry pa  reticularis  has  a  long  geological  range  in  Paleozoic 
time."  The  range  of  fish  must  be  carried  below  the  Devonian  and 
Silurian  (where  it  was  previously  supposed  to  begin)  because  of  the 
discovery  of  the  wonderful  fish  remains  in  the  Harding  sandstone  of 
Canyon,  Colo. ,  associated  with  a  Trenton  limestone  invertebral  e  fa  una. 

In  order  to  discuss  the  problems  of  the  time  relations  of  organisms 
it  is  necessary  to  use  the  terms  range  ami  distribution  to  refer  respec- 
tively to  geological  and  geographical  space,  and  to  note  that  the  facts 
concerning  the  range  of  species  and  genera  are  stated  in  terms  signi- 
fying position  in  and  thickness  of  formations.  Range  in  time,  often 
referred  to,  must  be  determined  by  relationship  of  the  faunas  or 
species  to  one  another,  and  this  is  another  method  of  the  discrimina- 
tion of  the  faunas,  a  method  which  is  neither  geographical  nor  geolog- 
ical, but,  as  we  shall  see,  organic,  and  which  is  strictly  a  measure  of 
the  life  history  of  organisms  in  evolutional  succession  one  to  another. 

The  importance  of  the  distinction  between  range  and  distribution, 
as  applied  to  fossils,  is  apparent  when  it  is  considered  that  the  evolu- 
tion or  modification  of  the  form  of  organisms  may  be  coincident  either 
with  change  of  place  during  the  same  epoch  of  time  or  with  passage 
of  time  in  the  same  area  of  space.  Fossils  can  be  used  as  indicators 
of  uniformity  of  geological  horizon  only  within  the  limits  of  their 
modification  by  conditions  of  geographical  distribution.  If  the  form 
of  a  fossil  varies  according  to  the  nature  of  the  sediments  in  which  it 
is  buried,  indicating  different  conditions  of  life,  the  extent  of  that 
variation  and  the  relation  of  the  change  of  form  to  the  particular 
nature  of  the  sediments  must  be  observed  before  the  characters  of  the 
fossils  can  be  accurately  applied  in  discriminating  their  age. 

It  has  been  ascertained,  as  will  be  illustrated  beyond,  that  a  fossil 
species  may  recur  at  successive  zones  for  a  thousand  or  more  feet  of 
thickness  of  strata  without  showing  greater  modification  of  form 
than  is  expressed  in  specimens  of  the  same  species  obtained  from  the 
same  stratum.  It  can  also  be  shown  that  the  species  making  up  the 
fauna  of  rocks  not  over  100  miles  distant  from  each  other,  which  by 
other  means  are  proved  to  be  at  the  same  geological  horizon,  may 
present  greater  differences  than  the  successive  faunas  of  a  single  sec- 
tion extending  over  a  range  of  many  hundreds  of  feet.  These  facts 
lead  to  the  discrimination  of  the  idea  of  variation  and  to  the  applica- 
tion of  that  term  to  indicate  differences  expressed  by  specimens  of 
the  same  species — differences  arising  coincidently  with  extension  of 
geographical  distribution  and  change  in  conditions  of  environment; 
while  the  term  mutation  is  technically  applied  to  those  changes  of  form 
that  are  coincident  with  passage  of  time,  and  hence  to  generational 
succession  under  conditions  of  life  so  nearly  /he  same  that  extinction 
of  the  race  does  not  residt. 

In  treating  of  the  relations  of  organisms  to  time  and  of  their  evolu- 

Bull.  210—0:5 — r-2 


18  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull. 210. 

tional  history,  it  becomes  necessaiy  to  notice  the  fact  that  each  indi- 
vidual organism  expresses  the  characters  by  which  the  taxonomic 
divisions  of  all  ranks  are  defined.  When  one  speaks  of  a  species 
living  in  a  certain  locality  or  at  a  particular  period  of  time,  the 
expression  is  not  strictly  true;  the  species  (or  the  genus)  is  a  cate- 
gory, not  a  living  body. 

The  fact  in  the  case  is  that  individuals  live,  developing  the  charac- 
ters of  some  species,  or  of  the  specific  category.  Each  individual  is  no 
more. a  species  than  it  is  a  genus  or  order  or  class;  and  whenever  one 
is  speaking  of  the  time  range  of  a  genus  or  species,  it  is  necessary  to 
understand  that  what  is  meant  is  the  time  range  of  the  particular 
specific  or  generic  characters,  as  the  case  may  be.  By  forgetting  this 
point  one  is  liable  to  think  that  the  species  cited  as  characteristic  of 
a  particular  epoch  of  geological  time  suddenly  became  extinct  when 
the  formation  holding  it  is  succeeded  by  another  containing  different 
species. 

So  long  as  representatives  of  a  genus  continue  to  appear  it  is 
necessary  to  assume  that  there  has  been  a  continuous  succession  of 
living  individuals  arising  by  direct  generation  one  from  another. 
Whenever  a  new  species  appears  in  the  rocks  it  is  not  to  be  supposed 
that  it  had  no  immediate  ancestors  living  at  the  time  of  sedimenta- 
tion of  the  subjacent  formations.  So  long  as  a  family  exists  in  the 
world,  it  is  also  necessary  to  assume  that  genera  and  species  have 
continuously  existed,  and  their  absence  from  the  formations  does  not 
indicate  that  they  did  not  live  in  the  zones  of  sedimentation  which 
lack  their  remains. 

These  observations  make  plain  the  reason  for  the  introduction  of 
the  ideas  expressed  by  the  terms  migration  and  shifting  of  faunas,  to 
account  for  absence  of  faunas,  in  the  place  of  the  idea  of  extinction 
held  by  the  earlier  geologists.  Not  onty  must  we  conceive  of  whole 
faunas,  as  well  as  individual  species,  migrating,  but  it  is  necessary 
to  assume  that,  coexistent  with  thick  formations  that  are  barren  of 
fossils  there  were  living,  in  probably  not  very  distant  localities,  faunas 
made  up  of  abundant  individuals  of  many  kinds  of  different  species 
and  genera.  This  fact  will  explain  also  why  it  is  necessary  to  take 
into  consideration  the  question  of  migration  in  order  to  make  corre- 
lations with  precision.  Other  problems,  which  will  be  discussed 
farther  on,  are  suggested  by  the  fact  that  the  evolutional  accounting 
for  divergence  of  characters  implies  always  a  continuous,  unbroken 
series  of  generations  for  each  race  of  organisms  until  it  becomes 
extinct.  The  characters  which  are  of  specific  rank  at  one  time  in  the 
history  of  a  race  can  not  take  generic  rank  in  another  part  of  the  his- 
tory. The  passage  from  varietal  to  specific  rank,  advocated  by  Darwin 
in  the  "Origin"  as  the  mode  by  which  species  originate,  does  not  apply 
to  specific  characters,  since  the  reason  for  the  distinction  between 
variety  and  species  is,  so  far  as  the  characters  are  concerned,  purely  a 


vfiLLiAMS.1  ANIMAL    AND    PLANT    AGGREGATES.  19 

question  of  permanency.  The  evanescence  of  the  varietal  character  in 
generation  is  the  reason  for  calling  it  varietal;  when  it  becomes  fixed 
and  is  repeated  without  change  its  rank  in  the  vital  economy  deter- 
mines whether  it  he  classed  as  a  specific,  generic,  ordinal,  or  class 
character.  The  changing  of  the  characters  of  all  ranks  of  taxonomic 
value  and  the  length  of  the  reproduction  of  the  several  characters 
without  change  are  chiefly  the  measures  of  that  taxonomic  rank,  since 
the  classification  of  the  organisms  into  the  taxonomic  groups,  species, 
genus,  order,  etc.,  is  regarded  as  natural  only  when  the  groups  of 
higher  rank  are  strictly  inclusive  of  those  of  next  lower  rank; 
and  this  could  happen  only  when  the  higher  characters  were  present 
before  the  distinctions  of  lower  rank  were  produced.  For  instance, 
it  would  be  impossible  to  conceive  of  the  distinctions  between  two 
genera  arising  by  evolution  before  the  ordinal  characters  had  been 
evolved — i.  e.,  in  a  natural  classification.  Hence,  the  higher  the  rank 
of  the  zoological  character  of  an  animal  the  more  ancient  the  history 
of  that  character.  The  application  of  the  principle  may  be  expressed 
by  saying  that  in  identification  of  fossil  specimens  for  purposes  of 
correlation  it  is  imperatively  necessa^  to  know  the  taxonomic  rank 
of  the  characters  by  which  the  identification  is  made.  If  a  generic 
character  be  interpreted  as  evidence  of  a  particular  species,  the  cor- 
relation inferred  from  the  fact  may  be  false,  since  the  range  of  the 
specific  character  in  most  cases  must  be  far  shorter  than  that  of  a 
generic  character  of  the  same  group  of  organisms. 

From  the  preceding  remarks  it  follows  that  fossils,  either  as  taxo- 
nomic aggregates  based  on  genetic  affinities  or  as  aggregates  asso- 
ciated on  the  basis  of  living  together,  can  not  be  considered  simply  by 
morphological  features,  but  that  their  chronological  relations  must  be 
distinctly  noted.  In  considering  a  species,  the  paleontologist  must  not 
only  consider  all  the  descendants  of  a  common  parent  and  those  differ- 
ing from  them  no  more  than  they  differ  from  one  another, but  must  con- 
sider the  descendants  which  do  differ,  and  the  length  of  time  during 
which  generation  continues  in  the  race  with  retention  of  the  specific 
characters.  The  idea  of  continuity  of  race  is  an  element  in  the  geo- 
logical study  of  species. 

In  like  manner  a  fauna  at  any  particular  instant  of  time  includes  all 
the  species  of  animals  living  together  under  a  particular,  though  very 
complex,  combination  of  environmental  conditions.  The  paleontolo- 
gist has  to  extend  this  idea  to  include  also  the  length  of  tim,e  through 
which  the  fauna  persists  without  loss  of  the  characters  essential  to  the 
fauna. 

Thus  the  paleontologist  is  not  only  forced  to  consider  the  time  rela- 
tions of  species  and  faunas,  but  it  is  by  means  of  the  relations  of  fossils  to 
one  another  that  periods  and  epochs  of  geological  time  are  distin- 
guished. 

A  living  species  may  be  classified  by  its  taxonomic  characters  and  be 


20  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

identified  with  forms  living  within  a  particular  geographical  area  of 
distribution ;  but  this  is  not  a  sufficient  discrimination  of  a  fossil  species. 
The  life  period  through  which  successive  generations  reproduce  the 
same  characters  is  an  important  part  of  the  paleontological  discrimina- 
tion of  a  species.  In  order  to  so  discriminate  fossil  species,  their  time 
relations  must  not  be  obscured  by  making  them  coordinate  with  the 
formations  in  which  the  fossils  are  preserved.  The  time  relations  of 
a  fauna  are  so  obscured  so  long  as  we  have,  for  instance,  no  means  of 
naming  the  fauna  of  the  Hamilton  formation  except  by  calling  it  the 
Hamilton  fauna.  So  long  as  we  have  but  a  formational  name  to  apply 
to  the  fauna,  an}^  question  as  to  the  continuance  of  the  fauna  later  in 
one  region  than  in  another  can  not  be  stated,  since  the  presence  of  the 
fauna  is  the  only  certain  evidence  of  the  upward  extension  of  the 
formation. 

In  order,  therefore,  to  deal  with  the  fauna  separately,  it  must  be 
designated  by  a  biological  name. 

GEOLOGICAL  FAUNAS  AND  THEIR  NOMENCLATURE. 

In  order  to  demonstrate  the  independence  of  faunal  history  from 
the  history  of  formations,  as  commonly  defined,  on  a  lithological  basis, 
it  has  been  found  necessary  to  study  a  fossil  fauna  as  an  aggregate 
of  species  living  together,  and  not  as  an  aggregate  of  fossil  remains 
occurring  in  and  characterizing  some  particular  geological  formation. 
As  commonly  understood  and  as  represented  in  the  collections  of 
museums,  fossils  are  tabulated  and  arranged  by  formations.  What- 
ever specimens  have  come  from  rocks  classified  as  the  Hamilton  for- 
mation, for  instance,  are  put  together  as  constituting  the  fauna  of 
the  Hamilton  formation,  and,  as  has  been  previously  noted,  this 
makes  it  rarely  possible  from  the  lists  (or  from  the  collections  so 
gathered)  to  determine  with  precision  the  range  of  the  species.  Again, 
rarely  in  the  older  lists  is  the  abundance  or  rarity  of  species  of  a 
fauna  noted,  and  the  collections  are  often  deceptive  in  this  respect, 
since  the  collector  is,  for  economical  reasons  alone,  apt  to  neglect 
common  forms,  while  rare  forms  are  selected  with  great  care  and 
every  trace  of  a  newly  discovered  species  is  retained. 

In  order,  therefore,  to  exhibit  the  full  time  value  of  fossil  faunas,  it 
becomes  necessary  to  observe  all  those  relations  which  the  individual 
fossils  bear  to  the  environment  in  which  they  lived  and  to  each  other 
as  they  were  associated  as  living  individuals  of  a  composite  fauna. 
In  thus  analyzing  fossil  faunas  the  most  conspicuous  fact  presented 
to  the  collector  is  the  different  degrees  of  abundance  in  the  general 
distribution  of  fossils  in  the  rocks.  Fossiliferous  zones  are  thus  set 
off  from  unfossilliferous  or  barren  zones.  Such  zones,  distinguished 
on  purely  paleontological  grounds,  are  entirely  distinct  from  the 
geological  formations  of  our  maps  and  geological  reports.  A  fos- 
siliferous zone  may  be  coextensive  with  a  formation  vertically  in  one 


wnxTAMs]      GEOLOGICAL    FAUNAS    AND    THEIR    NOMENCLATURE.        21 

section,  while  another  exposure  of  the  same  formation  may  be  broken 
up  into  several  fossiliferous  and  barren  zones;  and  still  another 
exposure  of  the  same  stratigraphical  formation  may  be  barren  of 
fossils  from  bottom  to  top. 

In  order  to  define  such  zones  it  becomes  necessaiy  to  note  and 
record  their  place  in  the  vertical  section  of  strata  making  the  forma- 
tion. This  is  indicated  most  conveniently  by  measuring  distance 
from  bottom  or  top  of  the  formation.  This  stratigraphical  position 
of  the  fossiliferous  zone  in  the  section  of  the  geological  formation  is 
its  horizon. 

A  fossiliferous  zone  may  occupy  the  same  horizon,  a  higher  horizon, 
or  a  lower  horizon  in  two  exposures  of  the  same  formation,  according 
as  its  position  relative  to  the  top  or  bottom  limits  of  the  formation  is 
the  same,  higher,  or  lower. 

A  fossiliferous  zone  may  increase  in  thickness  on  following  it  in 
one  direction,  and  decrease  in  the  opposite  direction,  in  proportion  as 
the  thickness  of  strata  through  Avhich  the  fossils  prevail  increases  or 
decreases  in  the  section. 

A  fossiliferous  zone  may  appear  gradually  on  following  the  strata 
upward,  or  it  may  appear  abruptly,  being  sharply  contrasted  with  a 
subjacent  nonfossiliferous  zone.  It  is  often  the  case  that  the  central 
portion  of  a  fossiliferous  zone  is  richer  in  kinds  of  fossils  than  are 
its  lower  or  upper  portions.  Species  which  are  proportionately  dom- 
inant at  the  first  appearance  of  the  fauna  may  disappear  when  the 
full  expression  of  the  fauna  is  seen,  but  reappear  as  the  species 
become  rare  in  the  upper  strata  of  the  zone. 

Thus,  for  instance,  Leiorhynchus  is  apt  to  occur  on  the  borders  of 
a  fossiliferous  zone,  and  is  less  frequently  met  with  in  the.  center  of  a 
richly  fossiliferous  zone;  Lingula  and  Discina  are  more  frequently 
found  in  sparsely  fossiliferous  zones  than  in  association  with  many 
other  species  or  genera. 

When  it  is  necessary  to  speak  of  a  portion  of  a  zone,  be  it  fossilifer- 
ous or  not,  the  terms  bed  or  band  or  stratum  are  used. 

In  this  connection  it  is  important  to  note  that  in  ordinary  sedi- 
mentary rocks,  limestone  (or  the  calcareous  element  of  the  sediments) 
is  reasonable  evidence  of  fossils,  although  present  in  a  pulverized 
condition;  and  for  purposes  of  discrimination  between  fossiliferous 
and  nonfossiliferous  zones,  limestone  should  be  classified  among  the 
fossiliferous  zones  although  the  forms  of  its  fossils  are  obliterated. 
In  like  manner  a  coal  bed  is  a  mass  of  fossil  plant  remains. 

The  kinds  of  strata  in  which  the  forms  of  fossils  are  in  general  best 
preserved  are  those  ranging  between  coarse  sandstone  and  pure 
limestone.  In  the  former  the  roughness  of  the  original  conditions 
under  which  the  formations  were  made  was  ill  adapted  for  marine 
organisms,  while  the  pure  limestones  were  formed  under  conditions 
favorable  for  such  organisms ;  but,  on  account  of  the  absence  of  sands 


<22  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

and  muds  to  cover  the  shells  and  other  hard  parts  of  the  fossils,  these 
were  ground  up  by  the  action  of  waves  and  currents,  and  their  sub- 
stance, though  not  their  forms,  was  preserved. 

A  zone  may  be  traced  from  place  to  place,  as  may  the  formation 
itself,  and  whenever  a  zone  runs  out  or  thickens,  or  breaks  up  into 
alternate  barren  and  fossiliferous  zones,  the  facts  relate  to  the  con- 
tinuity or  discontinuity  of  the  zone.  Contin  u  ity  and  discontin  u  ity  are, 
therefore,  terms  describing  physical  conditions,  and  are  applicable  in 
describing  the  persistence  or  reappearance  of  the  same  or  parts  of 
the  same  zone  in  different  localities.  But  a  zone  is  a  part  of  a  phys- 
ical formation  and  is  not  a  fauna  or  a  flora;  the  term  connotes  the 
geological  position  occupied  by  the  fauna,  as  the  term  province  con- 
notes the  geographical  area  of  distribution  of  a  fauna. 

Just  as  it  is  presumable  that  the  separate  observed  localities  of  a 
living  fauna  are  continuous,  and  that  all  of  them  together  make  up  the 
geographical  area  or  province  of  the  distribution  of  the  fauna,  so  it  is 
presumable  that  all  the  outcrops  of  the  same  fossiliferous  zone  were 
originally  connected,  and  thus  that  there  has  been  a  continuous  zone 
representing  the  geological  range  of  each  particular  fauna  whose 
remains  characterize  the  zone. 

If  no  changes  in  geological  conditions  were  to  take  place  the  geo- 
graphical distribution  of  any  fauna  at  any  particular  time,  recent  or 
geological,  would  constitute  its  geographical  province,  and  thus  define 
the  geographical  limits  of  the  fauna.  It  is,  however,  evident  that 
geological  changes  have  been  and  are  constantly  going  on,  resulting 
in  the  migration  of  faunas  from  place  to  place.  It  is  quite  conceiv- 
able, therefore,  that  the  lapse  of  time  represented  by  the  presence  in 
the  strata  of  the  species  of  the  same  continuous  fauna  may  be  nonsyn- 
chronous  for  two  seel  ions  not  many  miles  apart  and  belonging  to  the 
same  geological  province. 

This  fact  would  be  explained  as  a  case  of  migration  of  the  fauna  as 
a  whole  over  the  bottom  of  the  ocean.  Such  a  case  may  be  stated  in 
the  following  way:  The  fauna  was  a  littoral  fauna,  living  along  a 
shore  facing  an  ocean  to  the  west ;  the  land  in  relation  to  ocean  level 
was  gradually  sinking  during  the  life  period  of  the  fauna,  causing  the 
littoral  conditions  of  the  water  to  transgress  toward  the  east.  As  the 
sinking  progressed  we  may  suppose  the  fauna  as  a  whole  to  creep 
along  eastward,  retaining  its  relationship  to  the  littoral  conditions  of 
environment  without  modification  of  its  species  or  loss  of  its  faunal 
integrity.  After  a  long  time  of  such  movement  in  the  same  direction 
it  is  quite  conceivable  that  the  whole  area  of  bottom  originally  occu- 
pied by  the  special  fauna  might  be  deserted,  and  that  too  within  the 
life  period  of  the  fauna,  which,  in  the  case  of  the  Hamilton  formation 
in  central  New  York,  was  a  time  long  enough  for  the  accumulation  of 
over  a  thousand  feet  of  argillaceous  shale  strata. 

The  record  of  such  a  migration  would  be  left  in  the  strata  of  the 


Williams.]       GEOLOGICAL    FAUNAS    AND    THETR    NOMENCLATURE.        23 

whole  region  occupied  by  the  sediment-receiving  sea;  but  the  place 
in  the  geological  section  of  the  more  eastern  part  of  the  area  marked 
by  the  presence  of  the  fauna  would  represent  a  different  period  or 
moment  of  time  from  the  place  in  the  more  western  section  containing 
the  same  fauna.  The  difference  in  time  could  easily  represent  half 
the  period  of  the  existence  of  the  fauna  in  the  province. 

The  fauna  in  such  a  case  may  be  supposed  to  slowly  adjust  itself 
to  its  evironment  by  migration  instead  of  by  modification,  keeping  the 
center  of  its  distribution  within  the  limits  of  the  favorable  conditions 
of  depth,  pressure,  salinity,  etc.  Instead  of  accepting  an  unfavorable 
environment  which  has  invaded  its  original  habitation,  it  keeps  its 
relation  to  the  favorable  conditions  by  changing  its  place  of  habita- 
tion, and  thus  by  slow  migration  maintains  uniform  conditions  of 
environment. 

If,  now,  we  adopt  the  term  equivalency  to  express  the  fact  that  the 
faunas  are  alike,  and  continuity  to  mean  that  the  stratigraphical  hori- 
zon of  a  zone  or  formation  is  the  same,  the  conclusion  which  has  been 
reached  may  be  expressed  by  saying  that  fauna!  equivalency  does  not 
necessarily  conform  to  format  ional  continuity,  except  for  areas  thai  are" 
narrow  in  relation  to  the  extent  of  the  distribution  of  the  fauna. 

This  same  principle  of  transgression  of  a  fossiliferous  zone  to  a 
lower  or  higher  horizon  in  a  formation  on  passing  from  place  to 
place,  applies  as  well  to  the  limestone  beds  as  to  the  other  lithological 
characteristics  of  a  formation.  On  account  of  the  transgression  it 
will  be  evident  that  formational  continuity  can  not  be  interpret '<  d  info 
exact  time  equivalency,  except  for  very  limited  geographical  areas,  the 
limits  of  which  must  be  determined  also  upon  other  evidence.  Not  only 
may  the  same  fossiliferous  zone  occupy  different  horizons  in  separate 
outcrops  of  the  same  formation,  but  the  same  formation  whose  strati- 
graphical  continuity  can  be  clearly  traced  is  presumably  of  diverse 
age  at  the  extremes  of  its  geographical  distribution  rather  than  of  the 
same  age.  Thus  area,  locality,  distance  apart,  are  geographical  terms 
for  which  zone,  horizon,  and  thickness  vertically  in  a  section  are  the 
corresponding  geological  terms. 

Systematic  position  in  a  geological  section  is,  like  geographical 
position  on  a  map,  a  means  of  locating  the  place  in  which  a  formation 
is  situated,  and  has  no  necessary  connection  with  the  tirru  at  which 
the  original  formation  of  the  sedimentary  deposit  was  made. 

Age,  contemporaneity,  equivalency,  and  correlation  are  terms  of  a 
different  order,  and  rest  for  their  discrimination  upon  the  evidence  of 
fossils  whose  preserved  forms  testify  of  the  time  when  particular 
species  of  organisms  lived,  and  thus  become  a  distinct  indication  of 
time  relations. 

Particular  fossil  species  are  not  confined  to  single  fossiliferous  zones, 
but  may  recur  again  and  again  in  successive  zones,,  irregularly  sepa- 
rated by  barren  or  nearly  barren  zones.     This  fact  is  itself  an  evidence 


24  CORRELATION  OF  GEOLOGICAL  FAUNAS.      [bitt.t,.  210. 

of  migration ;  since  a  recurrence  of  the  same  fossils  in  successive 
zones  can  be  rationally  interpreted  only  on  the  supposition  that  dur- 
ing the  sedimentation  of  the  barren  strata  the  successors  of  the  lower 
fossils  and  the  ancestors  of  those  that  followed  must  have  lived  in 
some  other  locality. 

The  successive  zones  thus  become  evidence  of  successive  occupation 
of  the  locality  at  which  the  stratigraphic  section  was  made,  and  of  an 
oscillation  in  the  movements  of  the  shifting  faunas.  In  order  to  ascer- 
tain whether  the  shiftings  are  in  one  direction,  or  back  and  forth,  the 
successive  zones  must  be  examined  and  the  fossils  compared.  The 
paleontologist  is  therefore  obliged  to  examine  every  foot  of  the  section 
exposed,  and  wherever  fossils  can  be  discovered  examination  must  be 
made  and  record  of  the  facts  be  preserved.  . 

When  a  fossiliferous  stratum  is  discovered  on  ascending  a  strati- 
graphical  section,  the  paleontological  observer  stops  and  samples 
the  stratum.  The  fossils  thus  gathered  constitute  a  faunule.  The 
fannule  may  be  found  to  extend  upward  for  several  inches,  or  possi- 
bly  several  feet,  without  apparent  change.  But  the  collector  should 
observe  carefully  to  discover  the  least  sign  of  change  in  the  fossil 
content  of  the  faunule. 

In  recording  the  contents  of  the  faunule,  care  is  needed  to  observe 
the  'proportionate  abundance  of  the  species.  If  collections  are  made 
with  this  idea  in  mind  the  species  may  stand  in  the  collection  in  the 
same  relation  to  one  another  as  in  the  natural  faunule.  In  addition  to 
the  collection,  notes  should  be  taken  of  the  abundant  and  common 
species — the  rarer  forms  will  be  discovered  as  such  during  the  study 
of  the  collection  in  the  laboratory. 

Each  fossiliferous  zone  should  be  examined,  and  particular  attention 
should  be  given  to  any  intercalated  bands  of  rock  not  like  the  pre- 
vailing rock  of  the  section,  which  may  bear  faunules  of  a  different 
fauna  from  the  one  prevailing  in  the  general  fossiliferous  zone  of  the 
region.  It  has  been  ascertained  that  these  slight  temporary  incur- 
sions of  a  fauna,  which  may  be  conspicuous  not  many  miles  distant, 
are  valuable  guides  to  the  direction  of  the  migration,  and  they  are  often 
forerunners  of  a  fauna  belonging  normally  at  a  higher  horizon  in  the 
formations. 

The  faunule  is  a  sample  of  the  faunal  contents  of  a  fossiliferous 
zone,  and,  as  a  sample,  care  should  be  taken  to  keep  together  in  their 
true  relations  all  the  species  of  the  individual  faunule,  so  as  to  permit 
no  doubt  as  to  the  natural  association  of  the  species  when  the  collec- 
tions come  to  be  more  minutely  studied  in  the  laboratory.  The  posi- 
tion of  the  faunule  in  relation  to  other  faunules  in  the  local  section 
should  be  observed  and  recorded  with  precision,  note  being  taken 
of  its  relative  position  in  the  fossiliferous  zone,  as  well  as  its  posi- 
tion in  the  formation  as  officially  mapped  and  described  in  Survey 
reports  of  the  region. 


Williams.]      GEOLOGICAL   FAUNAS    AND   THEIR   NOMENCLATURE.       25 

As  the  order  of  succession  of  the  faunules  is  of  great  importance, 
the  section  should  be  examined  from  bottom  to  top  and  each  fossilifer- 
ons  zone  noted,  and  faunules  obtained  and  recorded  as  frequently  as 
may  be  practicable.  In  practice  it  has  been  found  that  sections  in 
the  Devonian  of  New  York  and  Pennsylvania  are  sufficiently  alike 
for  a  radius  of  5  or  10  miles  to  make  the  separate  fossiliferons  zones 
recognizable  in  the  separate  sections  examined.  As  an  actually  con- 
tinuous section  vertical^  is  more  satisfactory  in  fannal  studies  for 
the  establishment  of  sequence  than  several  short  sections  whose  zones 
at  top  or  bottom  have  to  be  correlated  across  a  covered  interval,  it  is 
desirable  to  make  a  thoroughly  exhaustive  section,  extending  through 
the  formations  examined,  for  at  least  every  15  or  20  miles.  The  local 
shorter  sections  will  then  fall  into  their  places  in  relation  to  the 
general  sections  and  prevent  confusion  of  geological  mutation  with 
geographical  variation. 

In  reporting  the  faunules  the  identification  of  species  is  of  first 
importance,  but  for  study  of  the  biological  relations  of  the  faunas  as 
such  the  relative  abundance  and  evident  dominance  of  the  species  is 
of  almost  as  great  importance.  Only  thus  are  the  intimate  relations 
of  the  faunas  to  be  established  and  their  time  values  brought  to  light. 
After  these  two  sets  of  facts  are  recorded,  note  should  also  be  taken 
of  the  variability  expressed  by  the  species,  and  particularly  those 
which  are  the  dominant  species  of  the  faunule.  It  is  by  catching  the 
particular  characters  of  specific  form  which  express  variability,  and 
the  direction  of  the  changes  taking  place  in  the  form  of  the  fossils, 
that  genetic  kinship  of  faunules  is  traced. 

By  taking  note  of  these  characteristics  of  the  faunules  over  terri- 
tories several  hundred  miles  in  extent,  and  ranging  through  the  mid- 
dle and  upper  formations  of  the  Devonian  system,  it  has  been  possible 
to  formulate  several  valuable  rules  for  the  discrimination  and  inter- 
pretation of  fossil  faunas. 

Faunules  of  the  same  formation ,  located  together  in  the  same  general 
region,  are  more  closely  alike  in  constitution  and  proportionate  abun- 
dance than  those  of  widely  separate  regions.  Hence  it  follows  that  a 
fauna  has  a  local  expression.  The  details  and  exact  description  of 
this  local  faunal  expression  can  be  stated  in  terms  of  relative  abun- 
dance of  the  species  constituting  the  faunules. 

Although  over  wide  areas  some  of  the  species  of  a  general  fauna 
are  recognized,  the  limited  area  within  which  the  dominant  species  hold 
the  same  relative  dominance  in  numbers  over  the  other  species  may  be 
clearly  distinguished  by  the  statistics  of  the  faunules. 

By  comparison  of  the  species  of  the  faunules  in  their  relation  of 
relative  abundance  a  standard  list  of  dominant  species  is  formed,  and 
the  region  over  which  this  standard  is  preserved  may  be  called  the 
metropolis  of  the  fauna. 

By  the  same  method  the  faunules  express  for  several  numbers  in 


26  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210;    ; 

succession  the  same  dominant  species.  So  long  as  this  is  the  case  it 
may  be  assumed  that  the  same  fauna  is  under  examination.  When 
the  dominant  species  become  replaced  by  others  a  change  in  the  fauna 
is  taking  place,  though  it  may  be  shown  that  a  large  majority  of  the 
species  are  identical. 

This  maintenance  by  a  fauna  of  the  same  relations  of  abundance 
and  rarity  among  the  component  species  may  be  called  the  bionic 
equilibrium  of  the  fauna,  since  we  can  not  assume  that  the  whole 
fauna  dies  out  and  a  new  one  comes  in,  but  rather  must  believe  that 
the  fauna  changes  by  an  adjustment  of  equilibrium  among  its  species. 
Some  of  the  species  may  become  extinct,  some  of  them  may  be  modi- 
fied, and  some  may  be  left  behind  or  become  separated  from  the  main 
fauna  in  the  course  of  its  migration. 

The  term  bionic  refers  to  the  quality  of  persistence  in  transmitting 
the  same  characters  from  generation  to  generation,  a  quality  that  is 
recognized  by  the  presence  of  the  same  species  in  the  same  relative 
abundance  in  the  successive  faunules.  This  relative  abundance  of 
individuals  of  the  same  species  is  thus  taken  as  the  evidence  of  the 
bionic  rank  of  the  species  in  the  faunule  at  the  particular  time  in 
which  it  lived. 

It  has  been  observed  that  species  having  a  high  bionic  rank  are 
more  variable  than  those  with  low  bionic  rank;  therefore  it  is  to  be 
expected  that  the  varietal  forms  which  are  destined  to  become  the 
new  species  of  later  stages  of  the  fauna  will  be  found  among  the 
varietal  forms  of  dominant  species.  On  the  other  hand,  the  dominant 
species  of  a  new  fauna  are  likely  to  be  the  rare  forms  of  an  antecedent 
fauna  which  in  the  revolution  of  the  conditions  have  gained  in  bionic 
vigor  and  replaced  the  old  species  which  have  lost  their  bionic  domi- 
nance. It  is  to  catch  this  replacement  of  the  old  fauna  by  a  new  one 
that  the  observer  should  watch  with  care  the  thin  occasional  inter- 
calated beds  containing  species  either  wholly  or  in  part  different  from 
the  prevailing  fauna. 

It  has  been  often  observed  that  the  first  traces  of  the  new  over- 
lying fauna  are  to  be  detected  almost  pure  in  such  little  zones  occur- 
ring in  the  midst  of  the  normal  rocks  of  a  formation  several  feet 
or  even  tens  of  feet  below  its  actual  top.  Much  light  is  thrown 
upon  the  time  relations  of  faunas  and  upon  the  shifting  of  sedi- 
ments and  faunas  (to  be  ultimately  interpreted  into  elevation  and 
depression  of  parts  of  the  earth's  surface  in  relation  to  other  parts) 
by  noting  precisely  the  sequence  of  faunules,  and  particularly  the 
first  evidence  of  change  in  the  faunal  contents  of  the  zones  of  a  con- 
tinuous section. 

The  question  of  bionic  values  may  be  discussed  more  satisfactorily 
farther  on  in  this  paper,  after  the  presentation  of  concrete  examples 
to  be  used  as  illustrations.  The  general  conception  of  bionic  relations 
and  values  is  given  in  a  paper  first  read  before  the  Geological  Society 


Williams]  NOMENCLATURE    OF    FORMATIONS.  27 

of  Washington  in  1901. a  In  this  paper  definitions  tending  to  clarify 
thinking  in  these  directions  are  given.  In  another  paper, b  read 
before  the  Connecticut  Academy,  February  12,  1002,  a  brief  synopsis 
of  the  results  of  the  investigations  given  at  length  in  this  bulletin 
are  stated,  and  some  laws  not  specifically  formulated  in  this  paper 
are  there  given. 

In  order  to  call  attention  to  the  distinctions  which  are  made  by  a 
separation  of  the  discussion  of  fossil  faunas  from  that  of  the  geolog- 
ical formations  in  which  record  of  them  is  preserved,  it  may  prove 
useful  to  mention  in  this  place  the  terms  in  common  use  as  well  as 
those  here  introduced,  classified  according  to  their  application  to 
formations  or  faunas. 

NOMENCLATURE  OF  FORMATIONS. 

Formations  are  portions  of  the  rocky  crust  of  the  globe.  They  may 
be  called  igneous,  sedimentary,  or  metamorphic,  according  to  their 
mode  of  origin.  They  may  receive  lithological  names,  as  granite,  lime- 
stone, or  sandstone,  according  to  their  lithological  constitution. 

The  terms  sheets,  intrusive  or  extrusive  strata,  lenses  or  lentils, 
apply  to  formations  on  the  basis  of  their  geological  structure. 

They  are  called  crystalline,  schistose,  stratified,  or  oolitic,  on  the 
basis  of  their  texture. 

They  are  described  and  mapped  as  occupying  particular  geographical 
areas  on  the  basis  of  their  present  outcroppings  to  the  surface  of  the 
earth.  Their  thickness  is  determined  by  measuring  them  from  bot- 
tom to  top  in  a  line  vertical  to  the  plane  of  their  supposed  original 
deposition,  and  they  are  said  to  be  older  or  younger  according  to  their 
order  of  succession. 

They  are  named  on  the  basis  of  their  local,  prominent;,  or  first  - 
described  geographical  outcrops.  These  names  are  generally  geo- 
graphical terms. 

They  are  classified  primarily  on  the  basis  of  their  observed  order  of 
succession,  and  secondarily  on  the  basis  of  their  supposed  equiva- 
lence in  stratigraphical  position  with  other  formations  whose  order 
of  succession  has  been  established.  Such  terms  as  system,  series, 
groups,  stages,  zones,  and  beds  are  thus  applied  to  geological  for- 
mations; station,  section,  geological  column,  outcrop,  conformity  and 
unconformity,  province,  region,  and  like  terms  also  apply  to  geological 
formations. 

The  terms  correlation,  contemporaneity,  and  equivalency  apply  to 
formations,  and  may  be  used  on  the  basis  of  structural,  lithological, 
or  stratigraphical  evidence;  but  in  general  it  is  only  on  the  basis  of 
evidence  furnished  by  the  fossils  within  them  that  they  become  widely 
applicable. 

«The  discrimination  of  time  values  in  geology:  Jour.  Geol.,  Vol.  IX,  pp.  .")7<>  585. 
''Fossil  faunas  and  their  use  in  correlating  geological  formations:  Am.  Jour.  Sri..  4th  series, 
Vol.  XIII,  pp.  417-432. 


28  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [biti.l  210. 

The  geologist  is  liable  to  regard  fossils,  in  determination  of  cor- 
relation, as  of  the  same  order  as  minerals  (viz,  chondrodite)  or  pet- 
rographical  characters  (limestone,  sandstone),  and  then  to  associate 
them  with  other  diagnostic  characters  of  the  formations,  but  a  closer 
consideration  of  the  facts  will  show  that  the  quality  of  the  fossil  by 
which  it  becomes  evidence  of  a  particular  point  of  geological  time,  and 
from  which  it  derives  its  value  in  correlation,  is  biological,  and  is  due 
to  the  fact  that  in  biology  incessant  change  is  taking  place. 

While  a  formation  has  a  bottom  and  a  top  and  thickness;  which,  to 
be  sure,  must  have  started  and  ended  at  particular  points  of  time, 
those  particular  points  of  time  can  not  be  determined  in  the  general 
history  of  the  earth  except  upon  evidence  which  changed  with  the 
passage  of  time.  The  validity  of  this  statement  will  become  apparent 
by  attempting  to  ascertain  the  geological  age  of  an  igneous  rock  with- 
out noting  its  relation  to  some  fossil-bearing  rock. 

In  dealing  with  formations,  therefore,  whenever  fossils  are  brought 
in,  a  new  bodj^  of  evidence  is  introduced,  and  a  number  of  terms  not 
applicable  to  formations  are  required  for  the  scientific  discrimination 
of  this  evidence. 

FAUNAL  AGGREGATES. 

Fossils  when  spoken  of  in  aggregates  are  faunas  or  floras.  Faunas 
are  particularly  spoken  of  in  this  paper,  not  to  the  exclusion  of  floras, 
but  because  in  most  respects  the  remarks  which  apply  to  the  geolog- 
ical  relations  of  faunas  apply  also  to  floras.  The  term  fauna,  however, 
will  be  used  in  its  strict  sense  of  an  aggregate  of  animals.  The  first 
reason  for  making  the  distinction  between  formation  and  faunas  is 
that  the  aggregation  of  the  species  which  makes  up  a  fauna  is  not 
determined  by  the  formation.  The  generally  accepted  practice,  which 
was  formulated  in  Dewalque's  report a  for  the  committee  on  uniformity 
of  nomenclature  at  the  International  Geological  Congress  at  Berlin — 
by  which  the  chronological  divisions  (era,  period,  epoch,  and  age)  are 
adopted  as  names  for  the  duration  of  time  corresponding  to  the  strati- 
graphical  divisions  called  group,  system,  series,  and  stage — does  not  deal 
with  faunas  as  such  but  only  with  the  nomenclature  and  classification 
of  geological  formations. 

Professor  Renevier  took  a  step  toward  the  recognition  of  fossil 
faunas,  as  distinct  from  formations,  in  his  "Chronographe  Geolo- 
gique,"6  by  distinguishing  separate  "fades  "of  the  same  formation 
deposited  at  the  same  time  with  other  facies. 

In  1884  Renevier  defined  "facies"  as  follows: 

"Les  facies  sont  done  en  definitive  les  differ entes  sortes  de  forma- 
tions, sedimentaires  ou  autres,  qui  peuvent  s'etre  produites  simultane- 

oCompte  Rendu  Congres  Geol.  Internat.,  third  session,  Berlin,  1888,  p.  322. 
?>Compte  Rendu  Congres  Geol.  Internat.,  sixth  session,  Zurich,  1894,  p.  519. 


Williams]  FAUNAL    AGGREGATES.  29 

ment,  a  un  moment  quelconque  des  temps  geologiques,  comme  cela  se 
oasse  encore  au  temps  actuel. "  a 

Renevier,  although  distinguishing  between  the  duration  of  time  of 
the  formation  and  the  means  of  recognizing  that  duration,  viz,  the 
different  faunas  which  are  found  in  the  different  kinds  of  deposits, 
still  makes  the  time  division  synonymous  with  the  duration  of  the 
work  of  producing  the  formation,  not  the  duration  of  the  living  of 
the  organisms  whose  remains  are  seen  in  the  fossils. 

A  fossil  fauna  may  characterize  a  formation  without  having  its 
limits  (chronological)  determined  by  the  beginning  or  cessation  of 
deposition  of  sediments  making  up  the  formation.  In  fact,  a  fauna 
which  appears  in  full  force  at  the  base  of  a  formation  must  have 
existed  somewhere  for  a  long  geological  period  of  time  before  the 
specimen  of  it  (the  faunule)  which,  occupies  the  lower  layers  of  the 
formation  was  buried,  or  else  we  are  forced  to  assume  that  it  was 
'suddenly  created  on  the  spot. 

If  this  proposition  be  true,  and  I  think  no  modern  paleontologist 
will  question  it,  the  common  methods  of  correlating  the  time  equiva- 
lency of  formations  by  the  likeness  of  their  fossil  faunas  is  inaccurate 
at  least  by  such  a  length  of  time  as  would  be  required  for  the  estab- 
lishment of  that  coadaptation  of  the  species  which  characterizes  the 
fauna  during  its  whole  expression  in  the  given  formation.  The 
change  of  faunas  in  successive  formations  which  on  other  grounds 
may  reasonably  be  supposed  to  represent  continuous  sedimentation, 
frequently  is  very  abrupt  and  complete.  It  is  only  occasionally  that 
a  gradual  transition  of  the  species  is  actually  recorded  in  the  succes- 
sive beds  of  a  continous  rock  section.  And  within  the  limits  of  a 
stratified  formation,  as  generally  recognized,  the  same  species  prevail, 
not  always  presenting  the  same  relations  of  abundance  throughout, 
but  the  same  species,  and  each  one  with  less  amount  of  variation  than 
is  expressed  by  the  representatives  across  the  line  by  which  the  for- 
mations are  distinguished. 

What  takes  place  with  the  living  organisms  during  the  transition 
of  one  formation  to  another  has  not  been  thoroughly  observed  or  dis- 
cussed. This  failure  of  knowledge  is  certainly  in  some  measure  due 
to  the  practice  of  assuming  that  the  time  duration  of  the  fauna  is 
synonymous  with  the  time  duration  of  the  formation  which  in  some 
particular  locality  contains  it. 

In  order  to  differentiate  the  fauna  from  the  formation,  it  is  needful 
to  observe  the  characters  which  pertain  to  faunas  and  not  to  formations. 

A  fauna  is  an  association  of  species  which  for  some  reasons  natu- 
rally live  together.  It  is  described  in  terms  of  species,  genera,  orders, 
etc.,  and  not  by  formations  or  localities  in  which  it  temporarily  lived. 
A  faunule  is  a  local  sample  of  the  fauna.     The  fauna  at  a  particular 

aLoc.  cit.,  p.  528. 


30  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull  210. 

period  of  time  may  have  a  metropolis  or  center  of  distribution.  The 
species  of  the  fauna  may  migrate,  and  the  whole  fauna  with  its  metrop- 
olis may  shift.  The  composition  of  the  fauna  may  he  described  in 
terms  of  the  species,  to  each  one  of  which  degrees  of  relative  and 
actual  abundance  or  rarity  of  individuals,  and  smallness  or  largeness 
of  size  of  specimens,  may  be  applied. 

The  integrity  of  the  fauna  may  be  defined  as  the  preservation  of 
equilibrium  of  dominance  of  some  species  over  others,  and  the  life 
period  of  the  fauna  may  be  recognized  by  the  corporate  integrity  of 
the  fauna.  Geographical  distribution  and  geological  range  are  terms 
apptying  to  the  species  of  a  fauna. 

Adaptation  to  conditions  of  environment,  plasticity,  variability, 
permanency  of  characters,  and  evolutional  mutation  are  qualities  of 
species  of  the  same  or  successive  faunas,  and  may  be  detected  by 
comparison  of  specimens  from  different  geographical  or  geological 
positions. 

From  such  analyses  of  species  and  aggregates  of  species  in  corporate 
faunas  may  be  framed  conceptions  of  their  chronological  relations; 
and  thus  evidence  of  time  duration  may  be  gathered  in  terms  of  geo- 
graphical area  or  thickness  of  strata  occupied  by  the  fossil  remains  of 
the  once  living  races  of  organisms.  An  individual  specimen  of  a  spe- 
cies does  not  express  an  appreciable  length  of  time  duration,  but  only 
a  point  of  time  during  the  life  period  of  the  species.  Species  vary 
greatly  in  the  lengths  of  their  life  periods.  The  life  period  of  a  large 
number  of  known  fossil  species  is  greater  than  the  average  duration 
of  most  of  the  named  formational  divisions  of  smaller  size. 

The  life  period  of  genera  is  in  many  cases  greater  than  the  dura- 
tion represented  by  formational  systems.  Nevertheless,  an  approx- 
imation to  those  formational  divisions  which  have  been  found  con- 
venient in  actual  usage  is  presented  by  the  life  periods  of  species, 
genera,  and  orders  of  marine  organisms,  as  has  been  shown  by  a  ten- 
tative scheme  of  classification  on  a  bionic  basis,05  already  published. 
In  the  paper  presenting  this  scheme  it  was  pointed  out  that  in  the 
Paleozoic  is  recorded  the  total  life  period  of  trilobites  and  that  such 
genera  as  Olenellus,  Asaphus,  Phacops,  have  a  life  endurance  at  least 
of  the  same  order  of  length  as  the  grander  subdivisions  called  systems 
or  series  in  common  usage.  Again,  it  may  be  pointed  out  that  the 
life  history  of  such  species  as  Spirifer  radiatus,  arenosus,  disjuncfus, 
or  cameraius  is  of  the  same  order  of  magnitude  as  the  geological 
divisions  of  the  formation  scale  called  Niagara,  Oriskany,  Chemung, 
and  Coal  Measures.  In  the  paper  just  cited  it  was  shown  that  these 
portions  of  time  duration  are  the  measure  of  an  actual  power  of 
endurance  expressed  by  the  organisms  themselves. 

"  Jour.  Geol.,  Vol.  IX,  p.  587.    See  also  p.  133  of  this  bulletin. 


Williams]  FAUNAL    AGGREGATES.  31 

This  power  of  endurance  is  undoubtedly  an  exceedingly  complex 
fact,  but  it  is  recorded  simply  by  the  continued  appearance  of  fossils 
with  the  same  morphological  characters.  If  the  characters  are  of 
specific  rank  their  endurance  is  of  relatively  short  geological  time;  if 
the  characters  are  generic  they  are  repeated  for  a  longer  period  of  time, 
etc.  These  endurance  values  of  the  characters  of  organisms  were 
spoken  of  as  bionic.  The  general  term  chron  was  proposed  as  a  desig- 
nation for  a  division  of  geological  time,  and  thus  one  is  enabled  to 
speak  of  geochron  as  the  time  duration  expressed  by  formations,  and 
biochron  as  the  duration  expressed  bjr  the  life  history  of  organisms. 

A  definite  and  independent  value  (i.  e.,  independent  of  the  forma- 
tion scale)  was  given  to  the  chronological  terms  hemera,  epoch,  period, 
era,  eon  by  using  the  bionic  or  endurance  quality  of  organisms  as 
the  measure  of  them.  Thus  hemera  was  to  be  measured  by  the  endur- 
ance of  the  bionic  equilibrium  of  a  local  faunule;  epoch,  by  the 
endurance  of  species;  period,  by  the  endurance  of  genera;  era,  by  the 
endurance  of  families;  eon,  by  the  endurance  of  orders. 

One  other  set  of  terms  applies  peculiarly  to  faunas.  Fossil  faunas 
express  evidence  of  a  certain  amount  of  migration  or  shifting  of  place 
of  habitation  during  their  life  history.  Barrande  spoke  of  colonies. 
Recurrence  of  faunas  has  been  described.  In  case  a  marine  fauna 
shifts  upon  the  sea  bottom  during  differential  movements  of  the  crust 
of  the  earth  two  results  are  possible — either  the  bionic  equilibrium 
of  the  fauna  will  be  disturbed  and  thus  the  faunal  composition  will 
be  modified,  with  more  or  less  mutation  of  the  species,  or  the  faunal 
equilibrium  will  be  retained  and  the  fauna  in  its  integrity  will  appear 
at  a  higher  stratigraphical  position  in  the  region  to  which  it  migrates 
than  in  the  region  from  which  it  has  shifted.  This  will  be  expressed 
by  a  transgression  of  the  fauna  in  relation  to  the  formation.  It  may 
be  expressed  by  a  mingling  of  the  species  of  two  faunas;  then  it  is 
defined  as  transitional.  It  is  possible  to  have  such  oscillation  of 
orogenic  movements  that  a  region  may  be  reoccupied  by  a  fauna 
which  has  shifted  out  of  it  temporarily.  In  such  cases  there  will 
appear  in  the  stratigraphical  section  evidence  of  recurrence  of  faunas, 
and  the  "colonies"  of  Barrande  may  be  thus  explained,  in  so  far  as 
they  are  not  explained  by  disturbance  of  the  strata  after  sedimentation. 

As  orogenic  movements  presumably  cover  long  periods  of  time  in 
one  direction  for  a  given  area,  the  direction  of  the  induced  migrations 
of  organisms  wTould  also  be  in  one  general  direction,  thus  furnishing 
no  occasion  for  recurrence  of  faunas.  In  such  cases  the  order  of  the 
faunas  would  be  correctly  expressed,  though  in  two  sections  the  time 
represented  would  differ  at  top  and  bottom. 

Mingling  of  faunas  would  also  be  expressed  by  the  arrival  of  migrat- 
ing species  into  the  midst  of  a  native  fauna  before  the  shifting  was 
general. 


32  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

Such  movements  of  faunas  may  be  assumed  to  have  been  more  fre- 
quent and  more  apparent  in  such  portions  of  the  ocean  bed  as  were 
near  the  shore,  and  thus  where  the  sediments  were  in  process  of  rapid 
accumulation  and  were  expressed  by  varying  classes  of  sediments. 
The  Devonian  formations  of  the  upper  portion  of  the  Appalachian 
Basin  were  on  this  account  particularly  fitted  to  tell  the  story  of  shift- 
ing of  faunas,  and  in  the  following  pages  evidence  of  the  shifting, 
recurrence,  and  modification  of  faunas  is  reported,  and  it  will  be 
shown  that  the  movement  or  migration  of  a  fauna  may  occur  with 
only  slight  evolutional  mutation  of  the  species. 


CHAPTER    II. 
THE  GEOLOGICAL  EXPRESSION  OF  FAUNAL  MIGRATIONS. 

The  association  of  specific  difference  in  plants  and  animals  with 
geographical  distribution,  involving  difference  in  climate,  altitude, 
and  general  difference  in  environment,  has  been  noticed  by  natural- 
ists for  centuries.  It  was  a  problem  of  geographical  distribution, 
more  than  anything  else,  which  suggested  to  Darwin  the  accounting 
for  difference  in  organisms  b}7  evolution  through  the  agency  of  nat- 
ural selection.  In  a  letter  to  Moritz  Wagner,  Darwin  wrote,  in  1876, 
"It  was  such  cases  as  that  of  the  Galapagos  Archipelago  which  chiefly 
led  me  to  study  the  origin  of  species."" 

The  geologist,  however,  for  whom  the  record  of  change  in  fossils  is 
more  sharply  apparent  on  passing  vertically  through  successive  strata, 
is  accustomed  to  associate  change  with  sequence  of  time,  neglecting 
the  part  which  migration  and  associated  change  of  environmental 
conditions  may  play  in  the  modification  of  the  specific  composition  of 
fossil  faunas. 

It  is  commonly  known  that  great  thicknesses  of  limestone,  repre- 
senting immense  periods  of  geological  time,  are  dominated  from  bot- 
tom to  top  by  the  same  fauna;  while  shales  and  sandstones,  indicat- 
ing rapid  accumulation  of  sediment  and  change  in  conditions  of  the 
sea  bottom,  present  series  of  faunas  in  which  not  only  species  but 
genera  differ.  If  the  rate  of  evolution  during  the  long  periods  of 
time  represented  by  the  limestone  indicates  the  steadiness  with  which 
organisms  reproduce  their  kind  under  uniform  conditions  of  environ- 
ment, then  either  the  changes  of  environment  coincident  with  change 
of  sediments  must  be  the  occasion  of  the  modification  of  the  organ- 
isms observed  in  the  successive  faunas  of  the  second  case,  or  else  the 
faunas  have  shifted  with  the  change,  and  the  observed  difference  is 
due  to  migration  of  new  species  into  the  region  whose  conditions  have 
changed,  with  only  slight  immediate  change  in  the  character  of  the 
species. 

If  we  adopt  the  first  assumption,  viz,  that  the  rapid  changes  of 
environment  are  coincident  with  rapid  evolution,  the  irregularity  in 
rate  of  evolution  in  different  parts  of  the  globe  must  have  resulted 
in  great  diversity  of  organisms,  and  Huxley's  view,  that  likeness  of 
fossils  in  widely  distant  portions  of  the  globe  does  not  indicate  time 
equivalency,  must  be  accepted  as  substantially  correct.  If,  on  the 
other  hand,  we  adopt  the  second  inference,  viz,  that  coincident  with 

"Life  and  Letters,  Vol.  II,  p.  338,  New  York,  D.  Appleton  &  Co.,  1898. 

Bull.  210—03 3  33 


34  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

the  rapid  changes  of  environment  faunas  have  shifted  their  habita- 
tion, the  conclusion  would  be  that  there  was  a  slight  acceleration  in 
evolution  with  the  readjustment  of  the  faunas,  and  that  the  shiftings, 
when  of  a  general  nature,  would  result  in  modifications  of  the  faunas 
which  would  serve  as  means  of  a  closer  correlation  of  the  time  rela- 
tions of  geological  events,  not  only  in  one  quarter,  but  quite  around 
the  globe.  AVhile  the  first  of  these  inferences  is  not  inconsistent  with 
the  second,  the  first  does  not  furnish  an  explanation  of  the  constant 
considerable  change  of  genera  as  well  as  species  seen  on  comparing 
the  successive  faunas  of  any  continuous  section  if  followed  through 
several  hundred  feet  of  diverse  sediments.  In  either  case  the  observ- 
ing and  the  recording  of  the  differences  expressed  by  fossil  faunas  of 
the  same  horizon  coincident  with  geographical  distribution  promise 
to  throw  some  light  on  the  problems  of  time  measurement  of  organic 
evolution  and  to  test  the  value  of  fossils  as  means  of  geological 
correlation. 

The  possibility  that  a  fauna  may  preserve  its  integrity  by  shifting 
its  habitation  with  the  slow  changes  of  environmental  conditions  was 
suggested  by  Barrande's  theory  of  colonies.  He  believed  that  a  fauna 
characteristic  of  one  epoch  of  time,  by  isolation,  could  be  preserved 
in  a  restricted  basin,  while  all  the  general  faunas  were  destroyed  and 
replaced  by  others,  and  that  later,  in  a  second  or  third  epoch,  the 
representatives  of  the  preserved  "colony"  might  migrate  into  the 
general  seas  and  reappear  (out  of  stratigraphical  place)  in  the  midst 
of  the  succeeding  faunas.  The  theory  as  a  whole  did  not  commend 
itself  to  general  acceptance.  But  "  recurrence  of  fossils,"  the  fact  at 
the  basis  of  his  theory,  has  been  frequently  recorded;  and  the  theory 
that  a  fauna  may  be  preserved  in  one  region  later  than  in  another 
appears  to  have  much  evidence  to  support  it.  Barrande  was,  how- 
ever, not  an  evolutionist;  uniformity  and  continuity  of  species  was 
a  part  of  his  creed;  hence  he  did  not  consider  the  positive  aspect  of 
the  case,  nor  did  he  conceive  change  of  environment  to  be  a  cause  of 
modification;  he  saw  only  the  negative  side,  viz,  the  association 
of  uniformity  of  conditions  with  preservation  of  characters  among 
the  inhabitants.  This  conception  of  the  unchanging  character  of  the 
species  still  continues  to  influence  general  notions  of  correlation, 
although  we  are  theoretically  all  evolutionists. 

Correlation  by  identity  of  species  implies  that  the  rocks  contain- 
ing the  same  species  of  fossils  were  formed  at  the  same  period  of  time, 
and  on  this  basis  it  is  inferred  that  formations  belong  to  the  same 
geological  horizon  so  long  as  their  species  are  found  to  be  the  same. 
While  in  a  general  way  this  is  correct,  since  the  evolution  of  forms 
goes  on  at  a  very  slow  rate,  the  converse  is  not  true,  viz,  that  unlike- 
ness  of  species  is  evidence  of  a  different  age  for  the  formations  hold- 
ing them.  Sufficient  facts  are  now  gathered  to  prove  that  in  each 
great  province  different  faunas,  adjusted  to  the  different  conditions  of 


Williams]       GEOLOGICAL    EXPRESSION    OF    FAUNAL    MIGRATION.       35 

environment  in  the  province,  have  been  living  at  the  same  time,  as  is 
clearly  known  to  be  the  fact  in  the  case  of  geographical  distribution 
of  living  faunas  at  the  present  time  on  the  face  of  the  earth. 

The  term  fades  has  been  applied  to  the  peculiar  combination  of 
species  of  a  fauna  characteristic  of  particular,  restricted  conditions 
of  environment.  So  that  two  sets  of  species,  living  simply  under 
dijferent  conditions  of  enviroment,  are  said  to  express  different  facies 
of  the  fauna  of  the  period  in  which  they  lived.  In  attempting  to 
make  correlations  and  classifications  of  stratigraphical  formations, 
geologists  have  found  difficulty  in  distinguishing  between  the  differ- 
ent facies  of  the  fauna  of  the  same  period  and  the  successive  muta- 
tions of  the  fauna  consequent  upon  geological  succession.  To  put 
this  in  a  word,  difference  in  faunas  may  be  due  either  to  geographical 
distribution  or  to  geological  range. 

Geographical  distribution  furnishes  the  basis  of  classifying  living 
faunas  existing  on  the  earth  at  the  same  time,  and  the  facts  con- 
cerning it  are  so  well  known  that  no  one  need  hesitate  to  explain 
difference  of  living  faunas  by  difference  of  geographical  distribution. 
The  principal  fact  in  the  case  is  that  environments  of  different  kinds 
are  occupied  by  different  species.  This  is  a  matter  of  fact,  irrespec- 
tive of  any  theory  as  to  how  such  relation  of  the  faunas  to  their 
environment  has  come  about. 

When,  however,  we  are  led  to  ask  how  the  adjustments  came  about 
in  geological  time,  we  have  to  choose  an  answer  from  these  two  possi- 
bilities, viz,  either  (a)  slowly  progressing  and  relatively  constant 
evolution  has  taken  place  among  organisms  constantly  struggling 
together  and  varying,  or  (b)  faunas  become  rapidly  adjusted  to  new 
conditions,  attaining  a  biological  equilibrium,  and  then  maintain 
that  equilibrium  with  extremety  slight  variation  for  great  periods  of 
time,  under  like  conditions,  but  quickly  and  rapidly  suffer  specific 
modification  whenever  the  environment  changes  and  the  equilibrium 
is  thus  disturbed.  Such  a  disturbance,  it  is  assumed,  has  taken  place 
whenever  a  sudden  change  occurs  in  the  sequence  of  sediments  from 
one  formation  to  another  with  change  of  sediments  and  corresponding 
change  of  fossils. 

Instead  of  assuming  that  the  fossils  were  destroyed  at  such  points 
and  recreated  in  the  following  period,  the  theory  here  proposed  is 
that  the  faunas  have  shifted  over  the  ocean  bottom.  The  uppermost 
of  two  successive  faunules  in  a  single  continuous  section  is  presumed 
to  have  lived  synchronously  with  the  underlying  faunule,  but  in  a 
separate  region ;  and  at  the  point  where  the  faunal  change  occurred  the 
second  fauna  migrated  into  the  region,  expelling  and  replacing  the  first. 
Such  cases  are  not  universal,  but  it  is  assumed  that  the  shifting  of 
faunas  is  more  or  less  common.  In  other  words,  the  elevation  or 
depression  of  continents  in  relation  to  ocean  level,  which  involves 
"the  shifting  of  the  position  of  deep  or  shallow  or  shore  conditions, 


36  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

does  not  necessarily  involve  the  institution  of  a  new  combination  of 
conditions,  but  rather  causes  a  transfer  from  place  to  place  of  exist- 
ing conditions  of  environment.  Such  movement  of  the  earth's  sur- 
face, resulting  in  the  geographical  changing  of  the  conditions  of 
environment  for  each  particular  spot  on  the  surface,  would  necessitate 
the  movement  of  the  faunas  living  under  particular  conditions  or  else 
their  destruction.  They  must  either  shift  their  place  of  habitation 
as  the  conditions  favorable  to  their  existence  are  changed,  or,  if  they 
attempt  to  stay  on  the  same  spot,  they  must  adjust  themselves  to  new 
conditions  of  environment.  This  principle  of  migration  necessarily 
involves  a  change  in  the  geographical  distribution  of  the  living  faunas; 
that  the  species  should  be  modified  as  such  migration  takes  place  is 
a  natural  conclusion  to  be  drawn  from  the  facts. 

The  other  kind  of  change  which  organisms  undergo  during  the  lapse 
of  geological  time  may  occur  without  any  disturbance  of  the  physical 
conditions  of  the  province  in  which  they  live,  and  is  coincident  with 
the  passage  of  time  alone.  The  ordinary  theory  of  evolution  contem- 
plates a  modification  of  species  under  such  conditions,  a  gradual 
variation  of  form  coincident  with  the  continuance  of  the  species 
under  like  conditions  during  their  "struggle  for  existence."  The 
modification  they  suffer  is  then  due  to  "natural  selection"  and  the 
"survival  of  the  fittest."  I  say  this  is  the  prevalent  hypothesis  to 
account  for  the  modification  of  species  by  evolution.  It  is  altogether 
probable  that  both  these  methods  of  modification  have  been  effective 
to  a  greater  or  less  extent  in  producing  the  total  results  which  go 
under  the  name  of  evolution  of  species. 

But  the  paleontologist,  as  lie  studies  the  succession  of  species,  will 
have  his  attention  more  closely  called  to  the  modifications  which  are 
coordinate  with  the  geological  movements  of  the  surface  and  are 
expressed  in  changes  of  local  conditions  Avithin  the  whole  province  in 
which  the  organisms  live.  This  modification  by  forced  migration  has 
to  do  with  the  breaking  up  and  reinstituting  of  biological  equilibrium 
of  the  faunas,  and  in  less  measure  and  with  less  effect  with  the  prin- 
ciple of  struggle  for  existence  among  common  competitors. 

In  order  to  discuss  the  subject  of  the  migration  of  species  and  the 
effects  of  forced  migration  upon  faunas,  it  is  necessary  to  discriminate 
two  distinct  sets  of  facts  as  under  discussion  at  the  same  time.  In 
the  first  place,  there  are  the  geological  formations  in  which  the  fos- 
sils are  preserved,  which  are  made  of  fragmental  particles  of  sand  or 
mud  or  limestone,  massed  together  into  sheets  called  strata,  piled 
one  upon  another,  forming  geological  columns.  These  are  the  forma- 
tions of  the  geological  "time  scale."  These  are  local,  from  the  fact 
that  the  materials  of  which  they  are  composed  are  sediments  which 
have  been  deposited  under  water  and  have  necessarily  been  brought 
from  some  contiguous  lands  to  the  place  of  their  deposit.  Geological 
formations  are  thus,  from  the  nature  of  things,  local  deposits,  having 


Williams.]       GEOLOGICAL    EXPRESSION    OF    FAUNAL    MIGRATION.       37 

local  origin,  their  materials  having  been  brought  together  and  formed 
under  conditions  which  were  more  or  less  local  in  extent.  In  dealing 
with  the  classification  of  such  formations  the  question  of  their 
sequence,  their  thickness,  and  the  composition  of  their  materials 
must  first  be  taken  into  account.  In  correlating  two  formations  of 
this  kind  the  first  question  is  as  to  their  geographical  continuity.  If 
we  find  that  a  stratum  of  limestone  occupies  a  similar  place  in  the 
sections  of  two  regions  separated  by  50  miles  of  distance,  and  the 
sequence  for  both  regions  is  the  same,  it  is  safe  to  assume  that  we 
are  dealing  with  the  same  part  of  the  earth's  crust.  The  second 
question,  as  to  whether  the  two  parts  of  the  earth's  crust  thus  corre- 
lated were  formed  at  exactly  the  same  time,  does  not  interfere  with 
the  conclusion  that  the  formations  are  the  same  and  maybe  classified 
as  equivalent.  In  other  words,  it  is  possible  (and  there  are  examples 
which  show  that  it  is  a  fact)  that  the  conditions  at  one  particular  geo- 
graphical spot  have  been  repeated  in  the  same  order  at  a  distance 
removed  from  that  spot,  although  each  episode  of  the  second  region 
occurred  later  in  time  than  its  corresponding  episode  of  the  first 
region.  Such  phenomena  are  generally  explained  by  the  supposition 
of  the  rising  of  the  shores  or  the  sinking  of  the  same  in  relation  to 
sea  level,  with  "transgression  of  the  sea." 

The  second  set  of  facts  is  described  by  the  term  faunas.  The  faunas 
are  biological  quantities,  the  term  fauna  meaning  the  aggregate  of 
organisms  living  together  in  a  region  at  a  particular  period  of  time. 
Such  a  fauna  lived  during  the  formation  of  the  sediments  of  a  particu- 
lar formation,  and  on  account  of  this  fact  is  said  to  characterize  that 
formation. 

It  does  not  necessarily  follow,  however,  that  another  formation,  far 
removed  geographically  from  the  first,  which  contains  approximately 
the  same  species,  is,  on  that  account,  the  same  formation;  but  in  order 
even  to  understand  what  such  a  proposition  means  it  is  necessary  to 
differentiate  the  fauna  from  the  formation  and  to  conceive  of  the  two 
as  different  entities  and  as  not  either  intimately  or  necessarily  com- 
bined. The  discovery  that  the  limestones  of  two  separate  regions  were 
not  formed  during  exactly  the  same  interval  of  time  would  not  be 
sufficient  to  prove  them  to  be  different  formations,  for  the  deposition 
of  the  sediments  making  up  a  particular  formation  may  have  con- 
tinued at  one  point  after  it  had  ceased  and  was  replaced  by  the  depo- 
sition of  sediment  constituting  another  formation  in  a  separate  region, 
or  deposition  may  have  begun  earlier  at  one  spot  than  at  another. 
Such  a  state  of  facts  follows  necessarily  from  the  principle  of  regard- 
ing a  formation  as  a  unit  mass  of  rock  instead  of  a  unit  division  of 
time. 

On  the  principle  of  migration  of  faunas  it  is  quite  possible  that  two 
distinct  faunules  living  contemporaneously  in  two  adjacent  districts 
of  one  basin  might  be  arranged  consecutively  in  a  third  (also  adjacent) 


38  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

district.  In  such  a  case  the  formation  holding  the  two  faunas  would 
be  identified,  by  their  fossils,  as  belonging  to  two  separate  epochs; 
and  the  stratigrapher  would  take  the  third  example  as  proof  positive 
that  the  one  fauna  followed  the  other  and  therefore  that  the  two  epochs 
were  successive  and  not  contemporaneous. 

An  example  of  such  a  case  is  discussed  in  detail  beyond.  The  Che- 
mung formation  is  known  to  follow  (to  lie  above)  the  Hamilton  for- 
mation in  western  New  York  by  the  fact  that  normal  faunas  of  the 
former  are  some  thousand  feet  higher  up  in  the  section.  But  that  the 
faunas  are  actually  contemporaneous  in  a  part  of  their  existence  is 
shown  by  the  recurrence  of  a  faunule  of  Hamilton  species  at  Owego, 
N.  Y.,  in  the  midst  of  strata  containing  below  as  well  as  above  char- 
acteristic Chemung  fossils. 

These  two  sets  of  facts — the  formations  and  the  faunas — must  there- 
fore be  dealt  with  separately.  While  the  presence  of  the  fossils  of  a 
particular  fauna  does  stand  for  something  in  a  column  of  sedimentary 
rocks,  it  docs  not  stand  for  the  whole  of  any  particular  period  or  inter- 
val of  time.  It  represents  some  portion  of  the  life  period  of  the  fauna, 
but  the  limits  observed  in  a  local  column  between  one  fauna  and  a 
succeeding  one  may  not  be  the  horizons  of  the  beginning  or  of  the 
close  of  the  life  history  of  the  fauna;  they  may  be  the  limits  of  the 
formation  for  that  section. 

There  seems  to  be  necessity  of  considering  also  a  third  element, 
which  Mr.  Bailey  Willis  has  recently  emphasized.  I  refer  to  the  time 
element  of  geological  classification.  Formations  are  lithological  and 
physical.  Faunas  arc  biological  and  must  be  treated  of  as  living. 
Time  divisions  are  conceptions,  and  their  use  depends  upon  the 
accuracy  and  reliability  with  which  they  may  be  represented  by 
visible  formations  or  faunas. 

The  primary  basis  of  distinguishing  the  time  relation  of  formations 
is  stratigraphieal  sequence.  But  the  formation  itself  is  a  lithological 
aggregate,  and  the  lithological  characters  by  which  one  formation  is 
distinguished  from  another  have  no  regular  order  of  stratigraphieal 
sequence,  hence  stratigraphieal  sequence  has  no  positive  time  value; 
it  is  only  the  element  of  sequence  of  time  which  is  recorded  by  the 
observed  facts. 

When  faunas  are  considered  separately  from  formations,  in  this 
way,  we  are  ready  to  notice  that  faunas  may  have  shifted  geograph- 
ically, and  may  thus  cause  confusion  in  the  classification  and  correla- 
tion of  the  formations  of  contiguous  basins.  When  we  consider  the 
confusion  which  has  already  arisen  in  the  classification  of  the  geology 
of  the  various  counties  of  Pennsylvania,  which  is  probably  to  be 
accounted  for  in  this  way,  the  necessity  for  more  light  on  the  subject 
is  apparent.  The  consideration  of  a  possible  shifting  of  faunas  may 
therefore  be  necessary  to  the  proper  interpretation  of  facts  which 
otherwise  greatly  confuse  the  geologist.     Classification  based  upon 


Williams]       GEOLOGICAL    EXPEESSION    OF    FAUNAL    MIGRATION.        39 

succession  of  formations  often  differs  from  classification  based  upon 
the  succession  of  species,  and  the  paleontologist  is  often  found 
practically  differing  from  the  stratigrapher  in  his  interpretation  of 
the  correlation  of  the  rocks  in  any  particular  region. 

Although  the  matter  of  shifting  of  faunas  has  been,  in  a  general 
way,  involved  in  what  is  called  geographical  distribution,  I  am  not 
aware  that,  in  this  country,  it  was  deliberately  announced  as  a  fact 
until  about  1883  or  1884,  when  such  announcement  became  neces- 
sary in  order  to  explain  certain  facts  in  the  geology  of  New  York 
State  which  I  then  had  under  investigation.  The  most  conspicuous 
case  which  came  under  my  notice  was  reported  in  Bulletin  41  of  the 
United  States  Geological  Survey,  On  the  Fossil  Faunas  of  the  Upper 
Devonian — the  Genesee  Section,  New  York.  The  investigations 
which  led  to  the  publishing  of  that  report  were  carried  on  for  the 
direct  purpose  of  ascertaining  what  kind  of  modification  actually 
occurred  in  the  same  formation  when  it  was  minutely  and  compara- 
tively studied  for  a  few  hundred  miles  across  the  field  of  its  distri- 
bution. •  The  Upper  Devonian  was  taken  because  of  its  possession 
of  several  successive  faunas,  the  lack  of  disturbance  of  the  strata, 
and  the  wide  region  over  which  its  outcrops  could  be  studied  with- 
out any  doubt  as  to  their  stratigraphical  correlations.  The  investi- 
gation showed  unmistakably  that  the  constituent  faunas  which  make 
up  the  sequence  of  any  particular  section  had  shifted  back  and  forth 
over  the  region.  It  was  ascertained,  for  instance,  that  the  place  of 
the  fauna  belonging  to  the  Ithaca  group  corresponded  stratigraph- 
ically  to  the  lower  part  of  the  Portage  formation  of  the  western  part 
of  the  State;  whereas  to  the  east  the  Hamilton  faunas  crept  up  with 
some  of  their  speeies  into  the  same  stratigraphical  zone;  while  still 
farther  east  the  same  horizon,  geologically  speaking,  was  filled  by 
sediments  of  the  Oneonta  group,  which  seem  to  be  equivalent,  in  every 
respect  but  position,  to  portions  of  the  typical  Catskill  formation. 
Again,  in  1897  a  study  of  the  faunas  of  the  southern  Appalachian 
province,  in  the  southernmost  point  of  Virginia,  brought  to  light  the 
fact  that  actual  traces  of  the  Carboniferous  fauna  were  found  in  a 
position  in  the  sequence  which,  a  little  to  the  north,  was  found  to  be 
dominated  by  Chemung  species. a  Such  facts  can  be  explained  at 
present  only  by  supposing  that  there  was  a  shifting  of  the  faunas 
geographically  within  the  common  basin  in  which  the}^  lived. 

The  theory  of  the  migration  of  faunas,  then,  assumes  to  be  true  the 
proposition  that  two  faunas,  one  of  which  generally  succeeds  the 
other,  may  be  actually  contemporaneous  in  their  life  periods,  at  least 
during  the  end  of  one  and  the  beginning  of  the  other.  By  the  theory 
of  shifting  of  species  and  migration  of  faunas  it  is  easy  to  understand 
how  a  fauna  which  immediately  succeeds  any  other  particular  fauna 
of  a  given  region  (if  the  faunas  be  actually  different,  or  if  one  be 

«SeeOn  the  Southern  Devonian  formations:  Am.  Jour.  Sci.,  4th  scries,  Vol.  Ill,  ]S<)7,  pp.  393-403. 


40  CORRELATION    OP    GEOLOGICAL    FAUNAS.  [bull.  210. 

strongly  contrasted  with  the  other)  has  come  from  outside  the  par- 
ticular region  in  which  it  is  introduced  and  is  not  the  immediate 
evolutional  successor  of  the  underlying  fauna. 

The  supposition  that  two  faunas  will  evolve  separately  if  placed  in 
two  different  regions  implies  simply  the  fact  that  no  two  actually 
distinct  regions  can  he  supposed  to  have  exactly  the  same  conditions 
of  environment  or  the  same  actual  set  of  species.  Such  conditions 
are  frequently  observed,  as  on  two  sides  of  an  ocean,  or,  again,  along 
the  same  coast,  where  we  may  find  northern  and  southern  faunas. 
When  we  cross  from  one  ocean  to  another,  under  similar  climates,  it 
is  familiarly  observed  that  the  composition  of  faunas  living  under 
similar  physical  conditions  is  different.  Supposing,  in  this  way,  that 
we  have  a  set  of  similar  conditions  in  different  parts  of  a  basin  which 
are  separated  one  from  another  by  barriers  sufficient  to  prevent  easy 
intercourse  between  the  two  parts,  although  not  necessarily  prohibit- 
ing migration,  here  we  have  all  the  conditions  for  the  development  of 
special  faunas.  With  the  breaking  up  of  the  geological  conditions  of 
such  a  general  basin — as,  for  instance,  by  the  rising  of  the  bottom  in 
relation  to  the  surface  of  the  ocean,  or  by  the  sinking  of  another  part 
of  the  basin  so  as  to  bring  deeper  and  purer  waters  where  h?d  been 
prevailing  the  accumulation  of  shore  sediment — we  may  suppose  the 
conditions  of  environment  so  completely  changed  for  a  particular 
part  as  to  force  the  organisms  to  shift  their  position.  In  shifting, 
those  which  are  able  to  shift  and  migrate  would  migrate,  whereas 
those  which  are  less  capable  of  migration  must  necessarily  be  cut  off, 
or  at  least  be  removed  from  the  migrating  fauna  to  such  an  extent  as 
to  change  the  equilibrium  of  the  species.  Coincident  with  such  move- 
ment of  the  fauna  due  to  geological  changes  in  the  province,  it  is 
assumed  that  the  evolution  of  the  species  finding  favorable  conditions 
for  life  would  be  more  rapid  than  it  was  during  their  existence  in  the 
conditions  from  which  they  came,  the  biological  equilibrium  of  which 
had  for  a  long  period  of  time  been  approximately  fixed  and  rigid. 

Migration  as  a  stimulus  to  variation. — It  is  inferred  from  what  has 
been  already  said  that  the  more  rapid  changes  in  the  contents  of  a 
geological  fauna  have  been  caused,  or  certainly  stimulated,  by  the 
forced  geographical  change  of  place  of  residence  of  the  fauna  itself. 
This  may  be  formulated  under  the  term  modification  by  migration. 
When  it  is  attempted  to  explain  how  such  effects  are  produced  it 
becomes  evident  that  the  principle  of  variation  must  be  conceived  of 
as  affecting  the  species  of  the  fauna  more  intensely  when  the  environ- 
mental conditions  are  forcibly  modified  than  during  the  periods,  how- 
ever long,  in  which  the  biological  equilibrium  of  the  fauna  maintains 
its  integrity.  Throughout  the  whole  geological  column  there  are 
illustrations  of  this  fact  which  will  occur  to  paleontologists.  It  is  a 
common  observation  that  so  long  as  that  integrity  of  the  fauna  suffi- 
cient to  lead  to  regarding  the  stage  as  the  same  continues  through  a 


Williams. I       GEOLOGICAL    EXPRESSION    OE    FAUNAL    MIGRATION.       41 

series  of  sediments,  the  individual  species  suffer  but  slight  change, 
and  this  has  been  observed  through  hundreds  of  feet  of  limestones, 
binning  up  into  the  thousands,  and  not  confined  to  only  a  single  case. 
The  interpretation  of  this  fact  is  that  so  long  as  the  equilibrium  of  the 
species  composing  a  fauna  is  preserved  they  may  continue  to  reproduce 
and  live  on  without  any  considerable  modification  of  their  specific 
characteristics.  Interpreting  this  into  the  principles  of  evolution,  it 
means  that  natural  selection  having  attained  a  relative  equilibrium, 
evolution  will  stand  still,  in  so  far  as  the  modification  of  organisms  is 
concerned,  for  great  periods  of  time.  On  the  theory  of  modification 
by  migration  it  is  assumed  that  this  equilibrium  is  an  equilibrium  of 
active  forces  residing  in  the  organism,  which  are  held  in  the  state  of 
equilibrium  by  the  combination  of  circumstances  going  under  the 
name  of  "natural  selection."  There  is  also  implied,  however,  the  idea 
that  the  species  are  in  a  plastic  state,  ready  for  modification,  and  that 
those  which  survive  vigorously  are  in  a  more  plastic  state  than  those 
which  succumb  and  are  lost  in  the  fight. 

That  species  vary  so  soon  as  they  are  subjected  to  new  conditions 
of  environment  implies  that  the  variation  is  an  expression  of  special 
vigor  in  the  organism  and  not  a  sign  of  weakness — that  variation  is 
the  expression  of  vitality  (if  we  may  use  that  term  in  a  general  sense) 
and  is  not  a  consequence  of  competition  among  the  individuals  them- 
selves. Darwin  has  spoken  of  such  variation  as  "spontaneous  varia- 
tion;" that  is,  variation  which  is  not  accounted  for  on  the  principle 
of  natural  selection,  but  which  is  presumed  to  be  present  before  natu- 
ral selection  is  capable  of  acting  upon  the  morphological  characters 
of  the  organisms. 

This  interpretation  also  explains  another  fact  which  paleontologists 
have  frequently  observed — the  fact  that  succession  of  faunas  of  the 
same  general  facies  is  rarely  traceable  to  gradual  modification  of  a 
subjacent  fauna.  In  such  a  case  the  metropolis,  or  center  of  distri- 
bution, of  the  new  fauna  is  generally  (and  it  may  be  universally) 
found  in  a  different  geographical  area  from  that  of  the  old  fauna 
which  it  replaces. 


CHAPTER   III. 
FAITXAIj  dissection  of  middle  and  upper  devonian 

OF  THE  NEW  YORK  PROVINCE. 

The  collecting  of  statistics  to  illustrate  the  laws  of  faunal  history 
has  been  carried  to  a  higher  degree  of  perfection  for  the  Devonian 
faunas  than  for  any  other  fossil  faunas  of  North  America. 

This  is  partly  because  a  great  amount  of  information  regarding  the 
individual  species  of  the  faunas  had  been  acquired  before  these  par- 
ticular investigations  were  begun,  and  partly  because  for  a  number 
of  years  definite  attention  lias  been  given  to  gathering  and  recording 
the  exact  statistics  needed  for  the  purpose  of  solving  practical  diffi- 
culties in  this  particular  field  of  correlation. 

The  method  of  investigation  which  has  brought  out  these  facts  is 
formally  stated  in  Bulletin  41  of  the  U.  S.  Geological  Survey,  under 
the  head  of  "  Geographic  and  chronologic  relations  of  the  faunas," 
as  follows: 

It  is  necessary  to  recognize  the  effect  of  geographical  conditions  upon  faunas  as 
well  as  the  changes  incident  to  chronological  sequence  if  we  would  interpret  the 
confusion  existing  in  the  Devono-Carboniferous  deposits  of  the  eastern  portion  of 
our  continent.  But  the  assigning  of  the  Marshall  fauna  to  the  period  of  the  Cats- 
kill  group  does  not  settle  it.  Neither  does  the  expansion  of  the  Chemung  forma- 
tion to  receive  the  Waverly  fauna  nor  the  pulling  down  of  the  Carboniferous 
system  to  cover  the  Portage  formation  relieve  us  from  the  main  perplexities. 

It  is  only  by  disentangling  these  faunas  and  ascertaining  the  true  geographical 
and  chronological  relations  which  they  hear  to  one  another  that  the  difficulty  is 
to  be  met.  This  is  to  be  attained,  not  by  clinging  to  any  sharp  limits  of  a  strati- 
graphical  or  a  lithological  nature,  or  to  any  absolute  division  between  one  forma- 
tion and  the  following,  but  each  fauna  must  be  traced  upward  and  downward  and 
its  modifications  noted  until  it  is  replaced  by  another,  and  whatever  on  the  way  is 
interpolated  or  is  added  to  it  must  be  traced  to  its  origin  or  to  its  center  of  occur- 
rence. By  this  method  a  scale  marking  the  chronological  sequence  in  the  life  his- 
tory of  the  organisms  and  faunas  may  be  prepared  which  may  serve  as  a  definite 
standard  for  determining  the  relative  age  of  formations  quite  independent  of  the 
lithological  characters  of  the  sediments  which  were  being  continuously  thrown 
down,  these  being  in  main  part  determined  by  local  conditions  of  the  disintegrat- 
ing shores  and  distance  away  from  them.  By  themselves  the  rocks,  as  rocks, 
present  no  features  which  may  serve  as  indications  of  the  particular  stage  in 
geological  time  at  which  they  were  deposited. « 

Previous  work  in  correlation  had  been  conducted  on  the  funda- 
mental assumption  that  identity  of  fossils  is  sufficient  evidence  of 

a  On  the  fossil  faunas  of  the  Upper  Devonian— the  Genesee  section,  New  York,  by  Henry  S. 
Williams:  Bull.  U.  S.  Geol.  Survey  No.  41, 1887,  p.  21. 

42 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  43 

identity  of  the  formations  containing  them.  In  other  words,  it  had 
been  assumed  that  for  purposes  of  classification  in  the  time  scale  the 
formation  and  the  fauna  are  identical.  The  way  in  which  fossils 
have  been  customarily  labeled  has  prevented  a  testing  of  the  truth  of 
this  assumption.  If  there  be  any  distinction  in  time  value  between 
the  formation  and  its  fauna,  it  is  difficult  to  demonstrate  it  so  long  as 
the  only  name  and  designation  of  the  fauna  is  that  of  the  formation 
in  which  it  was  originally  found. 

If  the  "Chemung  formation  "be  extended  below  the  fossiliferous 
strata  of  Ithaca,  as  it  was  in  the  literature  before  1880,  then  the 
fossils  in  the  "Ithaca  group"  belong  to  the  Chemung  fauna.  When 
the  Ithaca  fauna  was  dissected  and  it  was  shown  that  the  species 
were  not  those  of  the  Chemung  fauna  above,  but  were  rather  modified 
successors  of  the  Hamilton  fauna/  it  became  clear  that,  faunally,  the 
Ithaca  group  was  not  a  part  of  the  Chemung  formation.  Neverthe- 
less, the  term  "Chemung"  was  still  retained  in  general  literature  for 
the  "period"  which  included  both  the  "Ithaca"  and  "Chemung" 
epochs,  so  that  the  real  issue  was  still  obscured  by  the  imperfection 
of  the  nomenclature  which  used  "  Chemung"  with  two  meanings/' 

The  terms  "Portage,"  "Hamilton,"  "Trenton," and  "Niagara"  are 
also  applied  in  this  double  sense  in  the  classification  of  formations, 
making  it  almost  impossible  to  frame  a  statement  which  will  express 
the  thought  that  formations  and  faunas  are  discriminated  upon  dif- 
ferent bases  and  that  their  limitations  may  not  be  identical. 

In  order  to  demonstrate  the  actual  facts  in  the  case,  it  has  been 
found  necessary  to  collect  a  large  number  of  statistics  regarding  the 
actual  faunal  contents  of  each  zone  in  some  well-known  formation, 
and  also  regarding  the  separate  faunules  taken  from  outcrops  of  the 
same  formation  over  an  extended  area. 

This  work  of  dissecting  and  analyzing  the  faunas  of  the  Devonian, 
begun  in  1881,  has  been  carried  on  continuously  since  that  time. 
Students  in  the  laboratory,  at  both  Cornell  and  Yale,  have  been  trained 
to  discriminate,  collect,  and  analyze  the  faunules,  and  to  observe 
accurately  the  range  and  distribution  of  every  fossil  coming  to  their 
notice.  Others  outside  have  adopted  the  method,  and,  thanks  to  the 
painstaking  and  energetic  labors  of  many  workers,  it  is  now  possible 
to  demonstrate  from  the  statistics  already  gathered  at  least  the  dis- 
tinction between  a  lithological  formation  and  a  fossil  fauna. 

It  is  now  possible  to  state  that  the  Tropidoleptus  fauna  of  the  Ham- 
ilton formation  persists  in  its  integrity  above  the  top  of  the  Hamilton 
formation;  that  in  eastern  New  York  it  occupies  a  place  in  the 
column  which  is  occupied  in  central  New  York  by  the  Ithaca  forma- 
tion and  in  the  Genesee  Valley  by  a  portion  of  the  Portage  formation. 

«On  the  fossil  faunas  of  the  Upper  Devonian  along  the  meridian  of  76°  30',  from  Tompkins 
County,  N.  Y.,  to  Bradford  County,  Pa.,  by  Henry  S.  Williams:  Bull.  U.  S.  Geol.  Survey  No.  3, 1884. 
*>See  Manual  of  Geology,  by  James  D.  Dana,  4th  edition,  1894,  p.  iU\. 


44  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  211 


This  state  of  things  has  been  already  partially  demonstrated  in 
respect  to  the  position  of  the  Catskill  formation  in  the  geological 
column. a  But  the  significance  of  the  facts  was  obscured  in  that  case 
by  the  fact  that  the  Catskill  as  a  pure  formation  is  distinguished  by 
its  red  sedimentation,  which,  therefore,  was  easily  discerned  in  the 
field  by  the  stratigraphical  geologist;  but  the  fossil  evidence  of  the 
Chemung,  though  constantly  annoying  him,  had  not  in  his  mind  the" 
distinct  stratigraphical  significance  which  he  attached  to  the  color 
ingredient  in  the  Catskill.  The  evidence  of  the  Catskill  was  clear, 
and  if  the  fossils  told  another  story,  so  much  the  worse  for  the  fossils. 
This  was  his  attitude. 

In  the  present  case  the  faunas  are  of  the  same  kind,  made  up  of 
marine  invertebrate  fossils.  The}r  are  distinctly  marine  in  all  cases, 
and  the  demonstration  may  be  expressed  in  mathematical  values. 
The  statistics  are  sufficient  and  are  gathered  from  a  field  that  is  wide 
enough  to  make  possible  the  comparison  of  the  faunules  in  terms  of 
composition,  frequency,  and  abundance.  The  variation  of  species, 
though  not  yet  demonstrated  hy  the  statistics,  is  strongly  indicated 
by  the  increasing  uncertainty  in  identification  of  the  species  in  one 
direction,  while  the  species  are  always  positively  identified  in  the 
central  region.  Great  promises  of  future  discoveries  in  this  direction 
are  offered  by  the  facts,  and  in  the  future  we  may  expect  to  see  the 
laws  of  variation  associated  with  transgression  of  the  faunas  clearly 
demonstrated. 

Enough  evidence  is  already  in  sight  to  show  that  at  any  particular 
point  of  time,  as  represented  by  a  common  geological  horizon  or  zone 
in  a  given  formation,  the  inhabitants  of  one  sea  differed  in  species 
within  a  relatively  small  distance  (50  miles);  and  within  200  miles 
the  faunas  may  be  entirely  different,  having  not  a  single  species  in 
common. 

The  facts  also  give  clear  evidence  of  the  shifting  of  the  fauna  with 
the  accumulation  of  the  sediments,  so  that  the  center  of  distribution 
of  each  fauna  changes  as  we  ascend  in  the  formation.  The  evidence 
points  to  this  shifting  of  the  total  fauna  as  the  occasion  of  rapid  modi- 
fication and  variation  of  the  species,  and  the  inference  is  drawn  that 
great  changes  of  conditions  were  coincident  with  great  shiftings  of 
the  fauna.  During  the  prevalence  of  a  fauna  in  a  common  center  of 
distribution,  very  little  evolution  took  place  for  long  periods  of  time, 
as  measured  by  thickness  of  sediments,  but  slight  shifting  in  the 
geographical  position  of  the  fauna  is  coincident  with  the  appearance 
of  new  varieties  and,  in  general,  with  disturbance  of  the  faunal  equi- 
librium. 

The  work  of  dissecting  the  contents  of  a  fauna  into  its  constituent 
faunules,  and  then  of  the  analysis  of  these  faunules  into  their  specific 
composition,  was   begun  at  Ithaca,  in   the   midst  of  the  abundant 

«Dual  nomenclature  in  geological  classification:  Jour.  Geol.,  Vol.  II,  1894,  pp.  145-160. 


I!  Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  45 

[Devonian  fossils  of  the  formations  outcropping  in  that  region.  The 
(first  attempts  to  define  the  separate  faunules  and  to  apply  names  to 
•  them  were  imperfect  on  account  of  the  absence  then  of  any  knowledge 
as  to  the  range,  distribution,  and  relative  abundance  or  rarity  of  the 
[component  species.  These  statistics  were  gathered  as  the  investiga- 
tions progressed.  Although  those  first  attempts  at  classification  on 
the  new  basis  are  now  superseded  by  classification  based  on  the  full 
appreciation  of  the  laws  of  shifting  of  faunas,  the  record  of  the  steps 
by  which  the  progress  has  been  made  will  indicate  how  from  the  study 
of  conspicuous  local  phenomena  broad  general  laws  have  been  devel- 
oped. 

INTRODUCTION   OF  A   FAUNAL  CLASSIFICATION   OF  THE 
DEVONIAN   SYSTEM. 

Bulletin  No.  .*>  of  the  U.  S.  Geological  Survey,  On  the  Fossil  Faunas 
of  the  Upper  Devonian  along  the  Meridian  of  7(3°  30',  etc.  (Cayuga 
Lake  meridian),  was  issued  in  1884.  In  it  is  given  an  analysis  of  the 
faunas  of  the  section,  from  the  Genesee  shale  near  the  head  of  the 
lake  to  the  Barclay  coal  in  Bradford  County,  Pa. 

The  classification  of  the  formations  was  based  upon  the  changes 
exhibited  in  the  faunas,  and  the  following  faunas  were  recognized,  in 
ascending  order,  viz : 

1.  Genesee  slate  fauna. 

2.  Portage  group;  1,300  feet,  including  the  Ithaca  fauna  and  several  faunules. 

3.  Chemung;  1,200  feet,  with  separate  faunules. 

4.  Catskill  rocks. 

The  Portage  included  the  lower  beds  with  the  Cardiola  fauna,  and 
the  upper  part  was  observed  to  be  nearly  or  wholly  barren.  Second- 
ary faunas  of  the  Portage  group  were  recognized  and  named  as  follows: 

1.  Cladochonus  fauna  (No.  48,  sec.  1113,  p.  11). 

2.  Spirifer  lsevis  fauna  (sec.  1101,  p.  12). 

(Both  of  these  were  traced  eastward  as  to  origin.) 

3.  Lingula  fauna  (Ithaca  shale,  No.  6,  sec.  1106,  p.  14). 

4.  Hamilton  recurrent  fauna  (No.  14  N.  sec.  1102  N,  p.  15). 

5.  Cryptonella  fauna  (sec.  1105,  p.  17). 

6.  Ithaca  fauna  proper,  Spirifer  mesicostalis  zone  (1102  B,  HOT,  p.  18  and  p.  20). 

(This  was  traced  to  the  eastward.) 
6a.  Recurrent  Portage  (Cardiola  speciosa  fauna;  1168,  p.  20). 

7.  Discina  fauna,  a  recurrent  Genesee  shale  fauna  (mentioned  on  pp.  20  and  30). 

(This  was  traced  westward  for  its  origin.) 

8.  Spirifer  laevis  recurrent  fauna  (pp.  20  and  30). 

9.  Lingula  fauna  (1162  A  and  B). 

10.  Orthis  tioga;  typical  Chemung  fauna  (1172  D,  1165-67,  p.  23). 

11.  Heliophyllum  halli  zone  (coral  zone;  1167  E,H,  p.  24). 

12.  Catskill. 

The  investigation  was  described  as  the  first  of  a  series  of  articles 
on  the  comparative  paleontology  of  the  Devonian  and  Carboniferous 
faunas.     The  manuscript  of  the  bulletin  was  prepared  ami  sent  to 


46  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

the  Survey  in  1883,  before  the  field  work  of  that  year  was  begun. 
The  field  work  of  1883  and  1884  was  planned  as  a  continuation  of  this 
earlier  work  in  and  south  of  Ithaca  which  had  been  conducted  pri- 
vately as  a  part  of  the  work  of  a  professor  of  Cornell  University,  and 
it  was  carried  on  under  the  auspices  of  the  U.  S.  Geological  Survey 
in  the  Genesee  Valley.  The  report  on  this  work  was  published  as 
Bulletin  41  of  the  U.  S.  Geological  Survey,  the  manuscript  of  which 
had  been  sent  in  on  August  2,  1886.  A  preliminary  report  of  the 
results  of  the  summer's  work  along  the  Genesee  Valley  was  prepared 
at  some  length  and  sent  to  the  Director.  This  paper  was  received  by 
the  Director  July  27,  1884,  and  is  numbered  1398  of  correspondence 
of  1884.  An  abstract  of  it  is  published  in  Science,  Vol.  II,  pp.  836, 
837,  dated  December  28,  1883. 

At  first  the  report  was  intended  for  publication  in  the  annual  report 
of  the  Director,  but  was  returned  for  enlargement  into  a  bulletin  and 
formed  a  basis  of  the  report  finally  published  as  Bulletin  No.  41.  The 
paper  sent  to  the  Director  in  1884  contained  a  classification  of  the 
successive  faunas  observed  on  passing  across  the  State  from  Wyoming 
County,  N.  Y.,  the  examination  extending  as  far  as  the  southern  part 
of  McKean  County,  Pa. 

Bulletin  No.  41,  on  the  Genesee  section,  was  published  in  the  year 
1887.  It  was  written  after  two  more  years  of  field  work  had  carried 
the  studies  westward,  as  well  as  eastward,  from  the  initial  section  at 
Cayuga  Lake.  In  1884  the  sections  from  Chautauqua  Comity,  N.  Y., 
to  Cleveland,  Ohio,  were  investigated,  and  in  the  following  summer 
(1885)  sections  across  the  corresponding  part  of  the  formations  were 
run  from  Chenango  County  to  Delaware  and  Otsego  counties. 

In  the  report  as  published  in  Bulletin  No.  41  the  faunal  zones 
recognized  were  as  follows: 

1.  Lingula  fauna  (sec.  468,  p.  31).     Genesee  formation. 

2.  Car diola  fauna  (sec.  472).     Portage  formation. 

3.  Early  Leiorhynchus  fauna  (sec.  476  G).     Green  shale  of  Chemung. 

4.  Spirifer  mesicostalis  fauna  (sec.  476,  p.  58).     Rushford  shale. 

5.  Streptorhynchus  and  Spirifer  disjunctus  fauna  proper  (sec.  477,  p.  65) .  Cuba 
sandstone. 

6.  Lingula  fauna  (second;  sec.  477  A  2,  p.  64). 

7.  Lamellibranch  fauna  (sec.  477  A  3,  p.  64). 

8.  Athyris  angelica  fauna  (sec.  477  H,  p.  67). 

9.  Flat-pebble  conglomerate;  Palaeanatina  typa  (sec.  486). 

10.  Ferruginous  sandstones;  Rhynchonella  allegania  (sec.  484.  p.  87). 

Two  important  subfaunas,  local  in  extent,  were  also  recognized, 
viz,  the  Centronella  julia  fauna  of  Rushford,  in  the  midst  of  the  zone 
covered  by  the  Sjoirifer  disjunctus  fauna,  and  the  Orthis  leonensis 
zone  south  of  Cuba  (p.  34).  On  the  same  page  it  was  stated  that  the 
several  faunas  do  not  indicate  particular  geological  horizons,  but  par- 
ticular conditions  of  environment  or  habitat,  which,  locally,  had  defi- 
nite place  in  the  column.  Each  of  the  faunas  was  dissected  as  it 
occurred  in  its  own  section  of  the  formations  (p.  38). 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  47 

In  188G,  in  a  paper  On  the  Classification  of  the  Upper  Devonian,® 
this  classification  of  the  faunas  was  further  elaborated  in  a  report  of 
investigations  based  on  the  examination  of  ten  sections  across  the 
same  formation,  made  at  intervals  of  about  50  miles,  and  reaching 
j  from  Newberry's  typical  Cuyahoga  section  at  Cleveland,  Ohio,  to 
i  the  Unadilla  section  of  Otsego  and  Delaware  counties,  N.  Y.  In 
the  list  there  given  the  different  faunas  were  spoken  of  as  faunas, 
distinguished  by  the  general  content  of  species,  and  stages  was  the 
name  applied  to  the  faunules  into  which  the  dominant  fauna  was 
divided.  On  this  basis  the  following  successive  faunas  were  recog- 
nized : 

A.  Hamilton  fauna  and  its  direct  successors. 

B.  Black  shale  fauna. 

C.  Portage  fauna. 

D.  Chemung  fauna. 

E.  Flat  pebble  conglomerate  fauna. 

F.  Catskill  fauna  and  flora. 

G.  Waver ly  fauna. 

H.  Olean  conglomerate  fauna  and  flora. 
J.  Barclay  coal  fauna. 

In  the  life  range  of  each  of  these  faunas  temporary  stages  were 
noted.  These  temporary  and  local  expressions  of  the  fauna  are 
called  faunules  in  the  present  paper.  Although  they  do  express  halt- 
ing places  or  stages  in  the  evolution  of  the  fauna,  they  are  not  full, 
but  rather  partial,  expressions  of  the  general  fauna,  reflecting  par- 
ticularly the  influence  of  local  conditions  of  environment;  and,  as 
the  statistics  show,  rarely  holding  any  peculiar  species,  but  holding 
the  common  species  of  the  fauna  in  particular  proportions  of  rarity 
and  abundance  of  individuals.  The  name  applied  to  each  is  derived 
from  some  particularly  abundant  species.  Thus,  in  the  series  of  local 
temporary  faunules  of  the  Hamilton  fauna,  eight  stages  were  recog- 
nized, as  first  reported  in  1886,  as  follows: 

A  1.  Paracyclas  lirata  stage  or  faunule. 

A  2.  Spirifera  lawis  stage  or  faunule. 

A  3.  Stropheodonta  mucronata  stage  or  faunule. 

A  4.  A  try  pa  reticularis  stage  or  faunule. 

A  5.  Leiorhynchus  globuliforine  stage  or  faunule. 

A  6.  Tropidoleptus  carinatus  stage  or  faunule. 

A  7.  Spirifer  mesistrialis  stage  or  faunule. 

A  6  f .  Second  recurrence  of  Tropidoleptus  stage  or  faunule. 

In  the  same  way  the  Black  shale  fauna  (B)  was  expressed  in  the 
following  five  local  temporary  faunules,  successive  to  each  other  in 
time : 

B.  Lingula  spatulata  stage  or  faunule;  Genesee  shale. 
B  1.  Second  Lingula  spatulata  stage;  Portage  shale. 
B  2.  Lingula  complanata  stage;  "  Ithaca  group. " 
B  3.  Lingula  spatulata,  third  stage;  Cleveland  shale 
B  4.  Lingula  complanata,  second  stage;  Chemung  shale. 


«Proc\  Am.  Assoc.  Adv.  ScL,  Vol.  XXXIV,  pp.  222-234. 


48  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210.  j 

The  Portage  fauna  (C)  was  analyzed  into  the  following  faunules: 

CI.  Cephalopod  stage  or  faunule,  Goniatites  and  large  Carcliada?. 

C  2.  Lamellibranch  stage,  Cardiola  speciosa. 

C  3.  Portage  sandstone,  a  generally  barren  zone. 

The  Chemung  fauna  (D),  or  Spirt fer  disjunctus  fauna,  was  analyzed 
into : 

D  1.  Orthis  tioga  stage  or  fannule. 

D  2.  Stropheodonta  (Cayuta)  mncronata  stage. 

D  3.  Athyris  angelica  stage. 

D  4.  Rhynchonella  contracta  stage. 

D  5.  Spirifer  altus  fauna. 

The  flat-pebble  conglomerate  (E),  as  illustrated  b}7  the  Wolf  Creek 
conglomerate  (sec.  483  C,  p.  8(3),  contains: 

E.  Palseanatina  typa  fauna. 

The  Catskill  (F)  was  recognized  in  the  Oneonta  sandstone  (F  1) 
and  the  typical  Catskill  (F  2);  but  except  by  the  presence  of  Holopty- 
chius  and  other  fish  remains,  characteristic  plants,  and  the  Amnigenia 
catskillens/.s,  the  fauna  and  flora  were  not  then  exactly  defined. 

The  Waverly  (G),  with  Syringothyris,  is  a  still  later  fauna  in  which 
three  faunules  were  observed : 

G  1.  Bedford  shale  stage  or  faunule. 

G  2.  Berea  grit  and  sandstone. 

G  3.  Cuyahoga  shale  and  sandstone. 

No  attempt  was  made  in  L886  to  elaborate  these  higher  faunules  of 
the  Waverly,  as  the  statistics  were  at  that  time  too  imperfect  for 
drawing  conclusions. 

REVISED   CLASSIFICATION   OF   FAUNAS. 

Revising  this  classification  now  in  the  light  of  the  fuller  exhibition 
of  the  facts,  some  of  the  distinctions  made  in  1885  are  believed  to  be 
too  refined  and  local  for  perpetuation  in  a  general  classification,  but 
a  few  of  the  points  then  made  may  be  adopted  for  general  use  in  dis- 
cussing the  faunas  of  the  whole  continent  and  in  comparison  with 
the  faunas  of  the  world. 

The  fauna  of  the  t}rpical  Hamilton  formation  (A)  may  be  appropri- 
ately called  the  Tropidoleptus  carinatus  fauna.  That  species  is  more 
characteristic  of  the  fauna  as  it  appears  in  its  purity  in  the  eastern 
New  York  province  than  is  Spirifer  (mucronatus)  pennatus  Atwater. 

The  second  fauna  of  the  Black  shales  (B)  may  be  appropriately 
called  the  Lingula  spatulata  fauna,  as  that  species  is  characteristic  of 
it  far  and  wide  when  in  its  purity,  is  rarely  entirely  absent,  and  may 
be  found,  if  diligently  searched  for,  in  a  typical  black  Devonian  shale 
almost  anywhere  in  the  interior  continental  basin. 

The  third  fauna  of  the  Portage  shales  (C)  may  be  called  the  Car- 
diola speciosa  fauna.     Although,  as  Hall  has  shown,  this  is   not  a 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  49 

pardiola,  as  strictly  interpreted,  and  the  name  Glyptocardia  was  pro- 
posed as  a  new  generic  name  in  1885 a  to  take  its  place,  the  fact  that 
in  Europe  as  well  as  in  this  country  this  generic  name  has  been 
applied  to  this  species  and  its  European  representative  makes  it  not 
inappropriate  as  a  name  for  the  fauna.  As  Hall  observed  in  discuss- 
ing this  species  ( Glyptocardia  ( Cardiola)  speciosa  Hall) : b 

It  is  probably  identical  with  the  Cardiola  retrostriata  (von  Buch)  of  various 
authors,  and  with  Cardium  palmatum  of  Goldfuss.  Its  citation  by  numerous 
authors  shows  its  wide  distribution  in  Europe. 

The  fourth  fauna  of  the  list  (D) — that  of  the  Chemung  formation 
of  the  east — is  the  Spirifer  disjunctus  fauna.  The  species  Spirifer 
disjunctus  is  undoubtedly  identical,  specifically,  with  the  form  which 
is  more  commonly  called  Spirifer  verneuili  by  European  geologists. 
There  are  several  varieties  of  it  which  are  present  in  some  regions 
in  which  the  typical  form  Sp.  disjunctus  is  wanting. 

These  four  faunas  may  now  be  named  and  distinguished.  In  the 
discussions  that  follow,  the  relation  to  these  of  other  faunas,  which 
may  eventually  be  classified  as  distinct,  will  also  be  considered. 

THE   STATISTICS  AND   THE  PLAN   OF  DISCUSSION. 

After  the  publication  of  the  classification  set  forth  in  the  paper  of 
1880 c*  a  large  number  of  investigations  were  undertaken,  not  only  in 
New  York,  but  in  other  parts  of  the  country,  which  throw  new  light 
upon  the  questions  then  raised.  But  nowhere  have  the  statistics  been 
so  well  gathered  as  in  New  York  State.  Particularly  valuable  have 
been  the  researches  of  Prof.  0.  S.  Prosser.  Other  contributions  have 
been  made  by  N.  H.  Darton,  J.  M.  Clarke,  S.  G.  Williams,  G.  D. 
Harris,  C.  E.  Beecher,  J.  J.  Stevenson,  E.  M.  Kindle,  Stuart  Weller, 
A.  W.  Grabau,  and  H.  F.  Cleland.  Many  others  have  taken  part 
in  accumulating  the  statistics,  dissecting  the  faunas  into  faunules, 
and  analyzing  the  faunules,  more  or  less  perfectly,  into  their  specific 
values,  as  expressed  by  abundance  or  raritj^and  in  terms  of  frequency 
of  appearance  in  successive  stratigraphical  zones  or  at  distributed  geo- 
graphical stations.  The  particular  part  of  the  geological  column  about 
which  the  fuller  statistics  are  gathered  is  also  that  part  of  it  which 
was  selected  in  1881  for  special  investigation — i.  e.,  the  middle  and 
upper  formations  of  the  Devonian  system. 

In  order  to  illustrate  the  method,  and  to  demonstrate  the  few  gener- 
alizations which  at  the  present  state  of  the  investigation  are  fairly 
well  established,  these  statistics  of  the  Devonian  will  be  digested  and 
interpreted  in  the  following  ways,  viz : 

The  order  of  discussion  will  be :  First,  a  presentation  of  the  facts 
regarding  the  faunas;  second,  the  dominant  and  characteristic  spe- 

a  Palaeontology  New  York,  Vol.  V,  Pt.  I,  Lamellibranchiata,  II,  text,  p.  xxxv. 

blbid.,  pp.  426-427. 

c  Classification  of  Upper  Devonian:  Proc.  Am.  Assoc.  Adv.  Sci.,  Vol.  XXXIV. 

Bull.  210—03 4 


50  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

cies  of  each  fauna  as  determined  by  study  of  the  statistics;  third, 
the  general  laws  regarding  the  history  of  faunas  and  their  use  in 
interpreting  the  correlation  of  formations  and  the  structure  and  devel- 
opment of  the  continent. 

The  faunas  specifically  examined  are: 

1.  Fauna  of  the  Hamilton  formation,  which  may  be  called  the 
Tropidoleptus  carinalus  fauna. 

2.  Fauna  of  the  Ithaca  formation,  which  may  be  called  the  Pro- 
ductella  speciosa  fauna. 

3.  Fauna  of  the  Chemung  formation,  designated  the  Spirifer  dis- 
junct us  fauna. 

Other  faunas  and  subfaunas  will  be  named  as  they  are  taken  up,  but 
the  statistics  of  these  three  faunas  are  ample  and  the3T  are  of  a  like 
facies,"  so  that  their  comparison  will  make  evident  the  laws  of  shifting 
of  faunas  and  their  modification  coincident  with  this  shifting,  with 
geographical  distribution  and  with  stratigraphical  succession. 

HAMILTON  FORMATION  AND  TROPIDOLEPTUS  CARINATUS  FAUNA. 

In  the  final  report  on  the  geology  of  the  Fourth  district  of  New  York 
(1843)  the  Hamilton  group  was  defined  as  the  twenty-fourth  group  of 
the  New  York  system,  and  with  others  was  included  in  the  Erie 
division.  In  the  later  classification,  of  which  Dana's  Manual  of 
Geology,  fourth  edition,  1894,  may  stand  as  an  exponent,  the  Hamil- 
ton group  includes  the  Marcellus  shale,  the  Goniatite  beds,  the 
Encrinal  beds,  the  Hamilton  shales,  and  the  Moscow  shales.  The 
Tully  limestone  is  also  included  by  some  authors;  for  the  present 
discussion,  however,  this  local  formation  may  be  treated  faunJly  as 
a  separate  formation.  Faunally,  the  series  of  sediments,  as  tar  /  are 
exhibited  in  central  New  York  (beginning  at  the  top  of  the  Ononda 
(Corniferous)  limestone  and  terminating  at  the  base  of  the  Tully  lime 
stone),  presents  a  continuity  which  leaves  no  doubt  as  to  the  genetic 
succession  of  a  common  fauna  from  the  base  to  the  top.  In  dealing 
with  this  fauna,  only  the  species  between  the  limits  of  the  top  of  the 
Onondaga  limestone  and  the  base  of  the  Tully  limestone,  when  these 
are  present,  will  be  considered  as  belonging  typically  to  the  Tropi- 
doleptus fauna.  But  the  published  lists  are,  on  the  one  hand,  too  full, 
because  they  contain  all  the  species  which  have  been  reported  from 
the  Hamilton  group  or  formation,  however  that  formation  has  been 
identified;  and,  on  the  other  hand,  they  are  not  sufficient  for  the 
purposes  of  this  paper,  because  locality  and  place  in  the  formation 
are  not  always  recorded  or  known.  It  has  been  necessary,  therefore, 
to  use  specially  prepared  statistics. 

In  order  to  ascertain  the  average  characteristics  of  the  fauna,  a 

«In  a  paper  read  before  the  Geological  Society  of  America  after  the  present  bulletin  had  gone 
to  press  I  proposed  the  term  homeotopic  to  express  this  likeness  of  facies  of  these  faunas.  See 
Bull.  Geol.  Soc.  Am.,  Vol.  XIV,  1903. 


WILLIAMS.] 


FAUNAL    DISSECTION    OF    THE    DEVONIAN. 


51 


large  set  of  local  faunules,  prepared  in  determining,  by  the  fossils, 
the  areal  distribution  of  the  formation,  has  been  examined,  and  only 
those  faunules  were  taken  which  hold  accredited  Hamilton  species. 
In  order  to  obtain  evidence  as  to  the  composition  of  the  fauna  in 
different  parts  of  its  history,  a  complete  series  of  the  faunules  of  each 
fossilif erous  zone  from  bottom  to  top  of  a  t3Tpical  section  of  the  forma- 
tion was  examined,  and  the  proportionate  abundance  of  species  for 
each  zone  and  the  range  of  the  species  were  thus  ascertained. 

TROPIDOLEPTUS  CARINATUS  FAUNA  AS  EXPRESSED   IN   EASTERN  COUN- 
TIES  OF   NEW   YORK   AND   PENNSYLVANIA. 

An  examination  of  the  faunal  lists  prepared  by  Prof.  C.  S.  Prossera 
for  the  eastern  counties  of  New  York  and  Pennsylvania  furnishes  146 
localities  from  which  fossils  of  the  Hamilton  formation  have  been 
carefully  collected  and  listed.  In  all  172  species  were  positively 
identified.  The  localities  are  distributed  over  the  counties  of  Madi- 
son, Chenango,  Broome,  Otsego,  Delaware,  Schoharie,  Albany,  Greene, 
Ulster,  and  Orange,  of  New  York;  and  Pike,  Monroe,  and  Carbon,  of 
Pennsylvania.  The  species  listed  in  these  tables  have  been  tabulated 
so  as  to  exhibit  the  number  of  times  each  species  is  recorded  in  the 
separate  faunules.  The  abundance  or  rarity  of  each  species  in  the 
particular  faunule  was  also  recorded. 

From  this  complete  tabulation  of  the  statistics  the  following  table 
has  been  prepared  to  show  the  species  which  stand  highest  in  respect 
to  frequency  of  appearance  in  the  faunules  of  the  region  studied. 

Table  I. — Tropidoleptus  car inatus  fauna:  Species  occurring  most  frequently  in 
the  Hamilton  formation  east  of  Cayuga  Lake. 

[Dominant  distributional  frequency  list  for  eastern  New  York.] 


1.  Spirifer  pennatus 

2.  Tropidoleptus  carinatus 

3.  Spirifer  granulosus 

4.  Chonetes  coronatus 

5.  Palaeoneilo  constricta  _ . 

6.  Nucula  bellistriata 

7.  Amboccelia  umbonata  _ . 

8.  Nuculites  triqueter 

9.  N.  oblongatus 

10.  Nucula  corbuliformis  . 

11.  Athyris  spiriferoides  . . 

12.  Phacops  rana 


^loSlitfef   Number  of 
at'wnich       poupsot 
found. 


113 
89 
59 
57 
56 
42 
40 
38 
35 
33 
32 
32 


localities. 


30 

27 
28 
26 
27 
23 
'J 'J 
22 
21 
L7 
24 
is 


Abun- 
dant. 


26 
22 

ll 
1() 
2 
4 
4 
1 
1 
4 
2 
1 


Common. 


33 
30 
15 
16 

5 
8 
8 
7 
3 
3 
5 
4 


a  The  classification  and  distribution  of  the  Hamilton  and  Chemung  series  of  central  and  eastern 
New  York:  Fifteenth  Ann.  Rept.  State  Geologist  New  York,  Part  1, 1895,  pp.  87-222. 

The  classification  and  distribution  of  the  Hamilton  and  Chemung  series  of  central  and  eastern 
New  York:  Seventeenth  Ann.  Rept.  State  Geologist  New  York,  Part  II,  1900,  pp.  67-327. 

The  Devonian  system  of  eastern  Pennsylvania  and  New  York:  Bull.  U.  S.  Geol.  Survey  No. 
120,  1894,  pp.  1-81. 


52  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

The  total  number  of  species  cited  in  faunule  lists  from  140  localities, 
divisible  into  30  groups  of  localities,  in  eastern  New  York  and  Penn- 
sylvania is  172.  In  addition  to  these  positive  identifications,  15 
species  are  named  with  a  query,  and  11  genera  not  positively  identi- 
fied by  species  are  cited.  From  these  statements  the  lists  must  be 
regarded  as  approximate,  not  perfect,  lists  of  the  species  of  the  fauna. 
We  must  await  further  investigations  to  perfect  the  conclusions 
drawn  from  them,  which  can  be  only  outlined  at  the  present  time. 

DISTRIBUTIONAL  VALUES   OF  THE  SPECIES. 

In  the  first  column,  after  the  name  of  the  species  in  Table  I,  is  given 
the  number  of  times  each  species  is  recorded  in  the  140  localities.  In 
the  second  column  the  localities  are  grouped  by  fives,  making  30 
groups  in  all,  and  the  number  of  such  groups  of  localities  in  which 
the  species  occurs  is  given. 

Analysis  of  these  two  sets  of  statistics  shows  that  the  12  species  of 
the  list  have  all  been  reported  from  32  or  more  of  the  140  localities, 
nearly  22  per  cent  of  the  whole.  When  the  distribution  is  based  on 
groups  of  five  localities  the  frequency  readies  17  out  of  30  times,  or 
nearly  59  per  cent,  showing  that  we  have  for  all  of  them  a  common 
distribution,  which  would  place  them  in  50  per  cent  or  more  of  the 
localities  examined  in  a  cursory  survey  of  the  regions  studied. 

The  best  6  of  the  list  show  a  frequency  of  occurrence  equal  to 
nearly  a  third  of  the  localities  examined,  and  the  same  species  all 
occur  in  as  man}"  as  23  of  the  30  groups  of  five,  and  the  best  5  out  of 
the  12  occur  in  26  out  of  30,  or  nearly  90  per  cent  of  the  cases.  It  is 
safe  to  assume,  therefore,  that  the  first  12  species  of  this  list  give  a 
fair  representation  of  the  dominant  fauna  of  the  Hamilton  formation 
as  it  is  expressed  in  eastern  New  York  and  Pennsylvania. 

FREQUENCY   VALUES   OF   THE  SPECIES. 

The  dominance  of  the  species  in  the  fauna  may  be  proved  by  noting 
the  number  of  times  each  species  is  reported  as  abundant  or  common- 
in  the  local  faunule  in  which  it  occurs.  This  kind  of  value  may  be 
called  the  frequency  value  of  the  species  in  the  particular  faunule. 
The  facts  for  this  test  are  given  in  the  third  and  fourth  columns;  the 
figures  in  the  third  column  express  the  number  of  times  the  species  is 
recorded  as  abundant,  and  those  in  the  fourth  column  the  number  of 
times  the  species  is  reported  as  common.  We  note  at  once  the  promi- 
nence of  the  first  four  species  of  the  list. 

The  first  species  is  cited  as  abundant  20  times  and  common  33  times; 
or  for  59  times  out  of  the  113  records  it  is  at  least  common.  This  spe- 
cies is  Spirifer  (mueronatus)  pennatus  of  Atwater. 

The  second  species  in  the  list,  Tropidoleptus  carinatus,  is  abundant 
22  times  and  common  30  times;  or  52  times  it  is  a  common  constituent 
of  the  fauna. 


Williams]  FAUNAL    DISSECTION    OF   THE    DEVONIAN.  53 

The  next  two  species,  Spirifer  granulosus  and  Chonetes  coronattis, 
are  common  26  times  out  of  59  and  57  occurrences,  respectively. 

The  remaining  species  of  the  list  are  occasionally  abundant  and 
common  for  from  4  to  12  times  out  of  from  32  to  50  occurrences;  or 
something  like  20  per  cent  of  the  times  they  were  observed  they  were 
common  species  in  the  faunule  analyzed. 

In  matter  of  relative  dominance  among  the  species  of  the  fauna  the 
list  is  therefore  representative,  and  since  all  the  remaining  160  spe- 
cies of  the  Hamilton  formation  of  this  region  (so  far  as  reported  in 
these  statistics)  are  both  less  frequent  and  less  abundant  in  the 
faunules  examined,  we  may  assume  that  we  have  here  not  only  the 
dominant  but  the  characteristic  species  of  this  Tropidoleptus  carinatus 
fauna. 

This  set  of  statistics  was  chosen  for  first  consideration  for  the  fol- 
lowing reasons: 

(1)  The  localities  are  distributed  over  a  considerable  territory,  so 
that  in  case  there  were  local  peculiarities  in  the  samples  of  the  fauna 
examined  they  might  be  detected  and  eliminated. 

(2)  Although  the  fauna  can  be  traced  upward  in  the  strata  above 
the  place  of  the  Genesee  formation,  in  the  greater  part  of  this  region 
the  pure  Chemung  fauna  does  not  appear  in  the  series  above  the 
Hamilton  fauna,  but  its  place  is  represented  by  the  sediments  of  the 
Catskill,  without  a  strictly  marine  fauna. 

(3)  The  faunas  are  all  gathered  and  studied  by  a  single  person; 
hence  the  personal  difference  in  estimating  specific  values  and  identi- 
fications is  eliminated,  and  whatever  may  be  the  possible  error  in 
identification  it  is  likely  to  be  uniformly  made,  so  that  as  bionic  units 
the  species  may  be  regarded  as  fairly  uniform  in  value,  the  same  name 
standing  for  the  same  fossil  form  in  each  case  reported. 

(4)  From  the  general  distribution  of  the  Hamilton  formation,  I 
have  estimated  that  this  northeast  corner  of  the  Appalachian  prov- 
ince is  likely  to  present  its  fauna  in  greater  purity  than  it  appears 
elsewhere  in  the  interior  continental  basin. 

(5)  The  statistics  are  gathered  and  studied  with  great  care  by  one 
thoroughly  familiar  with  the  species  and  keenly  aware  of  the  impor- 
tance of  making  accurate  analyses  of  the  faunas. 

I  believe,  therefore,  that  the  statistics  are  as  reliable  as  any  that  are 
published,  and  that  they  represent,  as  accurately  as  can  possibly  be 
reported  at  the  present  stage  of  knowledge,  the  essential  elements  of 
the  fauna  of  the  Hamilton  formation. 

RANGE  VALUES   OF  THE  SPECIES. 

In  order  to  define  a  fossil  fauna  it  is  not  sufficient  to  enumerate  the 
list  of  species  which  have  been  described  from  the  same  geological 
formation,  chiefly  because  in  such  a  list  will  be  found  species  from 
many  different  regions  and  from  rocks  of  different  stratigraphical 


54  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

horizon,  and   species  which  when  living  were   adjusted  to  different 
conditions  of  environment.® 

A  fossil  fauna  is  made  up  of  the  species  which  lived  together  under 
a  common  set  of  environmental  conditions  at  the  same  time,  and  also 
of  species  which  continued  to  be  associated  together  for  a  greater  or 
lesser  length  of  time  (they  and  their  descendants),  bearing  the  same 
relations  to  one  another.  It  is  this  twofold  extension  which  must  be 
considered  in  dealing  with  the  faunas  of  geological  time,  viz,  their 
geographical  distribution  and  their  geological  range.  The  geograph- 
ical distribution  will  indicate  the  limits  of  expansion  of  the  fauna, 
determined,  it  is  to  be  presumed,  chiefly  by  conditions  of  exterior 
environment.  The  geological  range  will  indicate  the  power  of  endur- 
ance of  the  whole  fauna,  and  of  the  constituent  species,  in  preserving- 
its  integrity  as  a  fauna,  generation  after  generation,  against  the 
adverse  changes  of  environment  and  against  encroachment  of  other 
species. 

In  order  to  get  a  definite  concepl  ion  of  a  fossil  fauna,  it  is  necessary 
to  ascertain  what  were  the  dominant  species.  Dominance  is  a  rela- 
tive term,  and  implies  an  equilibrium  among  the  several  constituent 
members  of  the  community.  So  complex  a  combination  of  forces  is 
represented  by  a  fauna  that  it  can  not  be  imagined  that  the  relative 
dominance  of  the  species  of  a  fauna  could  be  retained  through  any 
serious  disturbance  of  the  general  conditions  of  life.  A  fauna  thus 
characterized  may  be  conceived  of  as  keeping  the  equilibrium  (once 
established  among  its  constituent  species)  only  so  far  geographically 
as  the  same  conditions  of  environment  prevail,  and  only  so  long  geo- 
logically as  it  is  able  to  continue  breeding  and  living,  at  least  in  a 
metropolis  of  distribut  ion  whose  conditions  remain  approximately  con 
stant.  A  fauna  once  broken  up  in  its  biological  equilibrium  as  a 
fauna  must  come  to  an  end,  however  long  thereafter  individual  species 
may  persist. 

In  order  to  appty  these  principles  to  the  determination  of  the  essen- 
tial characteristics  of  the  Tropidoleptus  fauna,  two  kinds  of  statistics 
were  needed : 

(1)  Statistics  to  show  the  dominant  species  of  the  fauna  in  its  geo- 
graphical distribution  over  a  considerable  region  of  surface;  and 

(2)  Statistics  to  show  the  dominant  species  of  a  series  of  successive 
zones  ranging  through  a  considerable  thickness  of  rocks  in  a  single 
geographical  section. 

CAYUGA  LAKE  SECTION. 

In  order  to  provide  a  standard  list  of  the  fauna  of  what  is  called 
the  Hamilton  formation,  from  a  typical  section  of  the  formation,  I 
persuaded  Mr.  II.  F.  Cleland,  already  well  equipped  by  his  previous 
biological  training,  to  make  an  exhaustive  analysis  of  the  Hamilton 

«  Heterotopic  is  proposed  to  express  this  adjustment  to  diverse  conditions  of  environment.    See 
Bull.  Geol.  Soe.  Am.,  Vol.  XIV,  1893. 


Williams.]  FAUNAL    DISSECTION    OF   THE    DEVONIAN.  55 

formation  as  it  is  exposed  along  the  shores  of  Caynga  Lake  in  central 
New  York.  Dr.  Cleland  accomplished  the  work  successfully.  The 
paper  which  he  wrote,  containing  the  results  of  the  investigation,  was 
first  presented  as  a  thesis  for  the  doctorate  degree  conferred  by  Yale 
University  in  1900,  and  was  afterwards  published  as  a  bulletin  of 
the  U.  S.  Geological  Survey/'  wherein  the  statistics  here  used  may  be 
examined  in  detail. 

A  list  was  prepared,  based  upon  a  very  thorough  study  and  dissec- 
tion of  the  formation  from  bottom  to  top.  The  faunules  were  collected 
from  70  zones  of  the  1,224  feet6  of  strata  representing  the  Hamilton 
formation  of  this  region.  Upon  examination  of  the  collections  it 
was  decided  that,  faunally,  there  were  but  25  separate  faunal  aggre- 
gates represented  in  the  series.  These  were  spoken  of  in  his  paper  as 
zones,  and  marked  by  letters  from  A  to  Y.  The  species  were  distrib- 
uted quite  generally  throughout  the  several  zones;  but  each  zone — 
sometimes  a  few  feet  thick  and  occasionally  10  or  over  100  feet  thick — 
held  practically  the  same  faunule  from  bottom  to  top;  that  is,  the 
same  species  in  the  same  relative  abundance  as  compared  numerically 
with  each  other.  The  investigation  was  made  under  my  supervision, 
but  the  identifications  were  all  made  by  Dr.  Cleland,  who  gave  very 
careful  attention  to  the  discrimination  of  the  least  departure  from  the 
described  characteristics  of  the  species  cited. 

In  the  use  of  fossils  for  the  purpose  of  scientifically  measuring  geo- 
logical time  the  faunules  of  such  zones  as  Cleland  has  analyzed  and 
listed  may  be  called  bionlc  units  of  the  first  order;  the  time  repre- 
sented by  the  continuance  of. the  particular  faunal  equilibrium  of  such 
a  unit  may  be  called  a  Jiemera,  applying  the  term  nearly  in  the  original 
sense  of  Buckman/'  but  giving  it  a  definition.  It  may  be  described 
as  the  time  during  which  the  particular  individuals  of  a  given  fauna 
and  their  descendants  maintain  their  faunal  equilibrium  in  relation  to 
one  another  in  a  local  and  temporary  faunule,  as  expressed  by  the 
retention  of  the  same  species  in  the  same  relative  abundance  in  the 
faunal  aggregate. 

The  analysis  of  Dr.  Cleland's  lists  of  hemeral  faunules  and  the 
reduction  of  their  statistics  to  averages  gives  an  approximate  concep- 
tion of  the  constitution  of  the  fauna  as  a  whole,  viewed  in  its  relation 
of  range  through  the  whole  Hamilton  formation.  It  is  in  reality  the 
dominant  fauna  of  the  region  for  the  epoch  of  time  through  which  it 
preserved  its  integrity  as  a  fauna. 

Table  II  presents  the  results  of  such  an  analysis. 

«  A  study  of  the  Hamilton  formation  of  the  Cayuga  Lake  section  in  central  New  York,  by 
H.  F.  Cleland:  Bull.  U.  S.  Geol.  Survey  No.  206,  1903. 

''This  is  Prosser's  estimate  of  thickness.  Cleland  estimates  the  total  thickness  of  Hamilton 
to  be  1,100  feet  (Bull.  206,  p.  90). 

<?S.  S.  Buckman,  Quart.  Jour.  Geol.  Soc,  November,  1893,  Vol.  XLIX,  p.  481. 


56 


CORRELATION    OF    GEOLOGICAL    FAUNAS. 


[BULL.  210. 


Table  II. — Tropidoleptus  fauna:  Fourteen  species  occurring  most  frequently  in 
the  Hamilton  formation  of  Cayuga  Lake. 


[Dominant  range  frequency  list  for  Cayuga  Lake  meridian.] 

Num- 
ber of 
zones 

in 
which 
found. 

Num- 
ber of 
zones 

in 
which 
found. 

1.  Tropidoleptus  carinatus 

2.  Ambocoelia  timbonata 

3  Palseoneilo  constricta   . 

21 
21 
21 
20 
20 
20 
19 

8.  Chonetes  mucronatus  . . . 

9.  Athyris  spiriferoides 

10.  Nuculites triqueter ... 

1 1 .  Modiella  pygma?a    - 

18 
17 
17 

4.  Spirifer  pennatus 

5.  Phacops  rana 

6.  Cryphaeus  boothi 

7  Nucula  corbuliformis 

16 

12.  Tellinopsis  subemarginata . .  - 

13.  Stropheodonta  perplana 

14.  Nuculites  oblongatus 

16 
16 
16 

The  list  here  compiled  (Table  II)  exhibits  the  14  species  occurring 
most  frequently  in  the  25  zones  into  which  the  formation  was  divided 
at  Cayuga  Lake  exposures.  It  will  be  noticed  that  these  14  species 
occur  in  16  or  more  of  the  25  zones,  and  that  6  of  them  occur  in  20  or 
more  of  the  25  zones.  The  first  5  in  the  list  are  also  in  the  list  of  12 
characteristic  species  of  the  eastern  Hamilton  (Table  I,  p.  51).  These 
are  Tropidoleptus  carinatus,  Ambocoelia  umbonata,  Palwoneilo  con- 
stricta, Spirifer  (mucronatus)  pennatus,  and  Phacops  rana;  the 
remaining  7  of  the  dominant  list  are  found  in  the  Cayuga  Lake  sec- 
tion, but  they  are  not  among  the  more  widel}r  ranging  species  of  that 
section. 

Chonetes  coronatus  is  represented  in  13  of  the  zones,  in  both  the 
lowest  and  highest,  and  is  fairly  common  in  several  of  the  zones  in 
which  it  appears. 

Xucula  bellistriata  does  not  appear  in  the  6  lower  zones  at  Cayuga 
Lake,  but  is  seen  in  8  of  the  zones  above. 

Cryphaus  boothi,  which  appears  in  20  of  the  25  zones  of  the  Cayuga 
Lake  section,  is  not  common  in  the  eastern  sections.  It  was  discov- 
ered in  several  sections  about  Smyrna  and  Sherburne,  once  at  Sum- 
mit, and  from  Kingston  southward  the  species  is  again  occasionally 
reported,  13  times  out  of  36  stations. 

Chonetes  mucronatus  is  among  the  long-ranging  species  of  Cayuga 
Lake.  It  is  fairly  common  in  the  eastern  faunas,  but  not  among  the 
first  12. 

ModieTta  pygmcea  and  Stropheodonta  perplana  are  long-ranging 
species  in  the  formation,  and  are  frequent  in  the  localities  as  far  as 
Chenango  Valley,  and  again  from  Kingston  southward,  but  are  rare 
in  the  intermediate  region. 

Tellinopsis  subemarginata  and  Nuculites  oblongatus  are  frequently 
noted  in  the  zones  at  Cayuga  Lake,  and  are  also  fairly  common  east- 
ward, but  fail  to  appear  in  the  first  12  of  the  typical  list. 

Looking  over  the  range  of  the  species  in  the  zones  of  the  Hamilton 


WILLIAMS.] 


FAUNAL    DISSECTION    OF   THE    DEVONIAN. 


57 


formation  at  Caj^uga  Lake,  the  dominant  list  already  selected  presents 
the  most  characteristic  species  on  the  basis  of  frequency  of  appearance 
vertically  in  the  zones;  but,  allowing  for  imperfection  in  the  collecting, 
the  list  as  given  in  Table  I  may  still  stand  as  the  list  of  dominant 
species  of  the  fauna,  considered  geologically  as  well  as  geographically. 

EIGHTEENMILE   CREEK   SECTION. 

Another  test  of  the  correctness  of  the  list  of  dominant  species  of 
the  Tropidoleptus  carinatus  fauna  is  derived  from  a  study  of  the  lists 
of  species  reported  by  faunules  as  they  occur  in  the  section  of  the 
Hamilton  rocks  at  Eighteenmile  Creek.r/ 

Mr.  Grabau  made  an  exhaustive  study  of  the  zonal  succession  of 
faunules  throughout  the  Hamilton  of  Eighteenmile  Creek.  In  his 
list  35  zones  are  recognized.  The  total  number  of  species  named  by 
Mr.  Grabau  in  his  list  is  163,  but  10  of  these  are  not  positively  iden- 
tified with  an}^  known  species.  Hence  there  are  only  153  species 
positively  recognized  in  the  collections  studied  by  him.  Of  these 
the  following  12  are  the  more  frequently  represented  in  the  zones, 
the  first  9  of  them  appearing  in  at  least  17  out  of  the  35  zones,  or  in 
50  per  cent  of  the  zones. 

Table  III. — Tropidoleptus  fauna:   Twelve  species  occurring  most  frequent/!/  in 
the  Hamilton  formation  at  Eighteenmile  Creek. 

[Dominant  range  frequency  list  for  Eighteenmile  Creek.] 


Number 

of  zones 

in  which 

found. 

Number 

of  zones 

in  which 

found. 

1 .  Spirif er  pennatus 

28 

7.  Primitiopsis  prmctilifera  -  - 

8.  Stropheodonta  perplana  _  _  - 

9.  Orthothetes  arctistriatus  ._ 

10.  Rhipidomella  vanuxemi--. 

1 1 .  Productella  spinnlicosta 

12.  Cryphaetis  boothi 

18 

2.  Phacops  rana  .   

3.  Chonetes  lepidus 

26 

21 
20 
18 

18 

17 
17 

4.  Athyris  spirif eroides 

5.  Ambocoelia  umbonata 

6.  Chonetes  scitulus 

14 
14 
14 

It  will  be  noticed  that  4  of  the  species  of  this  list  belong  to  the 
dominant  list  of  eastern  New  York  (page  51),  and  these  1  are  among 
the  first  5  showing  most  frequent  occurrence  in  the  zones  of  the  forma- 
tion in  western  New  York,  appearing  in  18  or  more  of  the  35  zones. 
It  is  to  be  noted,  however,  that  several  of  the  species  of  the  list  for 
eastern  New  York  (Table  I)  are  rare  or  wanting  in  the  Eighteenmile 
Creek  section,  and  are  there  restricted  to  a  few  zones.  They  are 
the  following  species,  the  number  of  zones  in  which  they  appear  in 
the  Eighteenmile  Creek  section  being  expressed  by  the  figures  to  the 
right  of  the  name.     The  total  number  of  zones  is  35. 

flThe  faunas  of  the  Hamilton  group  of  Eighteenmile  Creek  and  vicinity  in  western  New  York, 
by  A.  W  Grabau:  Sixteenth  Ann.  Rept.  State  Geologist  New  York,  ]S«.),s.  vv.  ;>:{!  339. 


58 


CORRELATION    OF    GEOLOGICAL    FAUNAS. 


[bull.  210. 


Table  Ilia. — Dominant  eastern  species  not  dominant  in  the  Eighteenmile  Creek 

section. 

Spirifer  granulosus 10 

Chonetes  coronatus 6 

Palseoneilo  constricta 4 

Nuculites  triqueter 1 

Nucula  bellistriata . 0 

Nucula  corbulif ormis .  0 

There  are  also  several  species  in  the  range  list  of  Eighteenmile 
Creek  not  in  the  dominant  distributional  list  of  eastern  New  York. 
They  are: 

Table  Illb. — Dominant  Eighteenmile  Creek  species  not  dominant  in  the  eastern  ? 

New  York  region. 


HBfaun- 
ules. 

146  faun- 
ules. 

Chonetes  lepidus 

C.  scitulus .- 

Primitiopsis  punctUifera 

Stropheodonta  perplana ... 

11 

17 

0 

IT) 

Orthothetes  arctistriatus 

Rhipidomella  vanuxemi 

Productella  spinulicosta  . . 
Cryphaeus  boothi. 

12 

17 

0 

17 

The  numbers  in  this  list  indicate  the  number  of  times  the  species 
is  recorded  among  the  J  40  fail  miles  of  the  eastern  distribution  recorded 
by  Prosser;  these  numbers  indicate  that  the  species  are  rare  in  the 
East. 

It  is  evident,  therefore,  that  the  Hamilton  fauna  of  western  New 
York  is  considerably  modified  from  the  standard  presented  in  eastern 
New  York. 

CONSTRUCTION     OF     A      STANDARD      LIST      OF       THE      DOMINANT 
SPECIES    OF    THE    TROPIDOLEPTUS    FAUNA. 

These  several  local  lists  already  presented  may  be  assumed  to  give 
a  fair  representation  of  the  dominant  characteristics  of  the  Tropido- 
leptus  fauna,  derived  in  two  ways — first,  on  the  basis  of  frequency  of 
occurrence  in  geographical  distribution  for  a  region  in  which  the  for- 
mation is  typically  expressed ;  second,  on  the  basis  of  frequency  of 
recurrence  of  the  species  in  vertical  range  through  the  successive 
zones  of  a  continuous  section,  passing  from  the  bottom  to  the  top  of 
the  formation. 

The  statistics  in  all  cases  were  prepared  with  special  attention  to 
the  discovery  of  the  facts  used  in  the  present  discussion,  and  by  men 
who  were  well  acquainted  with  the  fauna  they  were  analyzing. 

Difference  of  opinion  regarding  the  identification  of  species  is  not 
alone  due  to  difference  in  knowledge.  The  same  person  is  more  likely 
to  use  specific  names  alike  in  successive  papers,  but  the  habit  is  not 
uniform,  as  statistics  show.  Nevertheless,  for  determining  values  of 
species  in  terms  of  abundance  or  frequency  of  occurrence,  lists  made 


WILLIAMS.] 


FAUNAL    DISSECTION    OF    THE    DEVONIAN. 


59 


by  the  same  man  are,  naturally,  more  likely  to  furnish  correct  com- 
parative statistics  than  lists  made  by  different  men. 

These  three  selected  cases  may  be  taken  as  offering  a  fair  basis  of 
reckoning,  the  results  derived  from  which  may  constitute  a  fairly 
satisfactory  standard,  though  they  can  not  be  regarded  as  final  in 
any  of  the  lists,  since  the  statistics  of  the  faunules  are  decidedly 
incomplete.  This  incompleteness  of  the  fundamental  statistics  of 
this  investigation,  while  important,  does  not  invalidate  the  general 
conclusions  which  are  drawn  from  them,  for,  although  the  exact  degree 
of  dominance  is  not  mathematically  expressed  by  the  figures,  or  by 
the  order  of  the  species  in  the  lists,  the  fact  of  dominance  is  clearly 
expressed  for  the  species  mentioned. 

In  order  to  reduce  to  a  minimum  the  errors  pertaining  to  the  sev- 
eral modes  of  measuring  the  bionic  values  of  the  species  the  average 
may  be  struck,  and  thus  dominance  of  both  kinds  may  be  expressed 
in  a  final  list  which  may  stand  as  a  standard  and  representative  list 
of  the  dominant  species  of  the  Tropidoleptus  carinatus  fauna. 

In  order  to  add  together  the  statistics  of  various  kinds  regarding 
the  same  species  the  several  fractions  may  be  reduced  to  percentages 
(Table  IV).  The  statistics  are  in  three  sets  and  are  expressed  in  fig- 
ures at  the  right  of  the  species  tabulated  in  the  preceding  tables  (I, 
II,  III).     The  figures  express  the  following  facts: 

(1)  The  geographic  frequency  of  occurrence  of  the  species  in  the 
146  sample  collections  made  in  eastern  New  York  and  Pennsylvania. 

(2)  The  frequency  of  recurrence  in  the  25  zones  making  up  the  ver- 
tical column  of  the  Cayuga  Lake  section. 

(3)  The  frequency  of  the  vertical  recurrence  of  the  species  in  the 
35  zones  of  the  Eighteenmile  Creek  section. 

The  total  number  of  stations  in  the  first  group  is  146;  the  total  num- 
ber of  zones  in  the  second  group  is  25;  the  total  number  of  zones  in 
the  third  group  is  35. 

By  reducing  the  fractions  to  approximate  percentage  values  we  get 
the  following:  table : 


Table  IV. — Tropidoleptus  fauna:  Preliminary  dominant  list. 


Spirifer  pennatns 

Tropidoleptus  carinatus 

Spirifer  granulosus 

Chonetes  coronatus 

Palaeoneilo  constricta  „ . 

Nucula  bellistriata 

Ambocoeria  umbonata-- 

Nuculites  triqueter 

N.  oblongatus 

Nucula  corbuliformis  . 
Athyris  spiriferoides  _ . . 
Phacops  rana 


Eastern 

New 
York. 


Per  cent. 

78 
60 
40 
40 
40 
29 
28 
28 
24 
23 
22 
22 


Pavn™    Eighteen- 

tJvP         mile 
Lake"        Creek. 


Pei 


cent. 

80 
84 
40 
52 
84 
32 
84 
68 
64 
76 
68 
80 


Per  cen  t. 

80 

23 

29 

17 

12 

0 

51 

3 

6 

0 

60 

74 


Ontario, 
Canada. 


5. 
Totai. 


Per  cent. 

238 

167 

109 

109 

136 

61 

163 

99 

94 

99 

150 

176 


Rank  of 
species. 


1 

3 

7 
8 
6 
12 
4 
9 
II 
K) 
5 
2 


60 


CORRELATION  OF  GEOLOGICAL  FAUNAS. 


[BULL.  210, 


In  this  table  columns  1,  2,  3  express,  approximately,  in  percent- 
ages, the  facts  shown  in  Tables  I,  II,  and  III;  column  4  indicates 
the  species  which  are  recorded  in  the  fauna  of  Ontario,  Canada  ;a 
column  5  gives  the  sum  of  the  percentages  in  the  first  three  columns, 
and  column  6  shows  the  relative  order  of  the  species,  according  to 
the  results  thus  reached. 

Tabulating  the  species  in  this  order  the  following  table  is  obtained : 

Table  V. — Tropidoleptus  fauna:  Standard  list  of  dominant  species  for  the  New 

York- Ontario  province. 


1.  Spirifer  pennatus 

2.  Phacops  rana 

3.  Tropidoleptus  carinatus 

4.  Amboccolia  umbonata  ... 

5.  Athyris  spiriferoides  - . . 

6.  Palgeoneilo  constricta. . 


Per  cent 

of  bionic 

value. 


7!) 

58 

54 

17 
i:» 


7.  Spirifer  granulosus  _ . 

8.  Chonetes  coronatus  . _ 

9.  Nuculites  triqueter . 

10.  Nucula  corbuliformis 

1 1 .  Nuculites  oblongatus 

12.  Nucula  bellistriata  . . 


Per  cent 

of  bionic 

value. 


36 
33 
33 
31 

20 


The  figures  to  the  right  in  this  list  express  in  percentage  the  approxi- 
mate bionic  value  for  each  of  the  species  as  obtained  from  the  sta- 
tistics before  us.  It  will  be  seen  that  there  are  10  species  which  have 
a  bionic  value  in  this  fauna  of  83  per  cent  and  over,  and  no  other 
species  attain  this  bionic  value  when  tested  by  the  several  modes  of 
estimating  them  which  have  been  here  defined. 

The  first  10  species  in  this  list  (Table  V)  may  be  regarded  as  the 
10  most  characteristic  species  of  the  fauna  of  the  Hamilton  formation 
as  it  is  seen  in  New  York  State,  as  determined  by  the  evidence  already 
presented. 

The  geographical  distribution  of  the  fauna  may  be  recognized  by 
the  distribution  of  these  species.  A  fauna  which  fails  to  contain  any 
of  them  can  not  be  said  to  be  the  Tropidoleptus  fauna,  although  it 
may  be  called  equivalent  (on  some  basis)  to  it. 

When  the  vertical  range  of  the  fauna  is  under  consideration,  so 
long  as  a  majority  of  these  10  species  continue  to  appear  in  the  rocks, 
although  lithologically  or  stratigraphically  they  lie  above  the  Hamil- 
ton formation,  it  will  be  correct  to  state  that  the  fauna  still  lives  and 
preserves  its  bionic  integrity  in  the  measure  of  dominance  of  these 
species.  When,  therefore,  the  question  as  to  upward  range  of  the 
Tropidoleptus  fauna  is  discussed,  these  species  should  be  considered 
as  the  standards  by  which  the  fauna  is  to  be  recognized,  irrespective 
of  the  stratigraphical  evidence  of  continuance  or  noncontinuance  of 
the  Hamilton  formation. 

The  effect  of  checking  up  the  eastern  list,  on  the  basis  of  the  vertical 


"On  some  additional  or  imperfectly  understood  fossils  from  the  Hamilton  formation  of 
Ontario,  with  a  revised  list  of  the  species  therefrom,  by  J.  F.  Whiteaves:  Contributions  to  Cana- 
dian Palaeontology,  1885-1898,  Vol.  I,  Part  V,  pp.  361-43(5,  Pis.  XLVIII-L 


Williams]  FA  UNA  L    DISSECTION    OF    THE    DEVONIAN.  61 

recurrence  frequency,  is  to  exalt  the  rank  of  the  species  Amboccdia 
umbonata,  Athyris  spiriferoides  and  Phacops  rana,  and  this  throws 
Nucula  and  Nuculites  to  the  end  of  the  list.  This  result  may  be 
attributed  to  the  influence  of  environmental  conditions  upon  the 
species,  for  the  conditions  are  more  favorable  for  lamellibranchs  in 
the  eastern  region,  and  more  favorable  for  trilobites  in  the  western. 
It  is,  secondly,  traceable  to  the  rarity  of  these  species  in  the  localities 
in  the  counties  of  Otsego,  Delaware,  Schoharie,  and  Albany,  which 
lowers  their  frequency  percentage  for  the  whole  area.  Their  fre- 
quency in  Madison  and  Chenango  counties,  and  again  in  Greene, 
Ulster,  and  Orange  counties,  and  across  the  State  line  in  Pennsyl- 
vania, Avould  entitle  them  to  the  prominence  they  hold  in  the  list  as 
furnished  by  the  other  evidence. 

I  conclude  from  the  balancing  up  of  the  various  kinds  of  evidence 
now  in  hand  that  the  last  list  (Table  V)  contains  the  twelve  most 
characteristic  species  of  this  fauna  as  it  appears  in  the  New  York 
province,  and  shows  the  order  of  approximate  rank  they  occupy  in  the 
fauna  as  a  whole. 

Examination  of  the  faunas  in  the  formations  succeeding  the  Hamil- 
ton formation  of  the  eastern  division  of  New  York  reveals  the  fact 
that  this  typical  Tropidoleptus  fauna  continued  to  appear  above  the 
strict  limits  of  the  formation,  though  associated  with  new  forms  dis- 
tinct from  those  of  the  Tropidoleptus  fauna. 

The  Hamilton  formation  is  regarded  as  terminating  where  theTully 
limestone  comes  in,  when  it  is  present,  and  where  the  Genesee  shale 
appears,  when  the  former  is  wanting.  When  neither  of  these  litho- 
logical  formations  is  present,  the  position  in  the  strata  was  traced 
from  place  to  place  with  great  care  by  the  lithological  character  of 
the  strata  with  the  aid  of  structure  and  minute  discrimination  of  the 
faunal  contents.  The  faunas  confirm  the  accuracy  of  the  geological 
work  of  Professor  Prosser,  and  of  the  dissection  of  the  local  sections 
made  by  him.  I  have  examined  his  reports  with  critical  scrutiny, 
and  have  great  confidence  in  the  interpretation  of  the  equivalency  of 
the  species  and  faunas  made  by  him.  The  evidence  of  change  in  the 
faunas  is  clear,  and  the  relative  order  of  the  succession  of  the  faunas 
is  always  the  same,  and  the  gradual  departure  of  the  less  conspicuous 
elements  of  the  earlier  fauna  is  apparent  as  the  faunas  are  traced 
upward  in  each  section. 

The  Ithaca  formation  is  succeeded  by  the  Oneonta,  and  above  the 
Oneonta  a  considerable  number  of  the  typical  species  of  the  Tropido- 
leptus fauna  still  appear.  These  species  continue  after  the  introduction 
of  Spirifer  meslcostalis  and  after  the  Spirifer  mesistrialis  fauna  was 
well  established  in  the  province.  The  Tropidoleptus  fauna  was  not 
entirely  dispersed  till  the  characteristic  Spirifer  disjunctus  of  the 
Chemung  had  arrived  in  central  New  York.  In  the  extreme  eastern 
counties  this  species  is  not  certainly  reported,  but  many  of  its  asso- 
ciates in  the  western  part  of  the  basin  are  introduced  before  the  entire 


62 


CORRELATION  OF  GEOLOGICAL  FAUNAS. 


[BULL,.  210. 


disappearance  of  the  Tropidoleptus  fauna  from  the  eastern  corner  of 
the  basin. 

On  following  these  faunas  westward  it  is  found  that  the  Tropido- 
leptus fauna  lies  entirely  below  the  Genesee  shale  in  the  Genesee 
Valley  and  farther  westward.  The  formations  called  Sherburne, 
Ithaca,  Oneonta,  and,  I  am  inclined  to  think,  a  considerable  part  of 
what  is  classified  as  Chemung  in  the  eastern  half  of  the  State,  lying 
above  the  Oneonta,  must  be  regarded,  on  stratigraphical  grounds,  as 
equivalent  to  the  Portage  formation  of  the  Genesee  Valley. 

EFFECT  OF  ADDITIONAL  STATISTICS. 

In  order  to  demonstrate  the  way  in  which  such  a  standard  list  as 
Table  V  is  affected  by  additional  statistics,  a  few  cases  are  left  for 
analysis  after  the  estimate  has  been  deliberately  made. 

The  faunules  of  the  Unadilla  region  of  Otsego  and  Delaware  coun- 
ties, in  eastern  New  York,  were  gathered  by  Prof.  C.  S.  Prosser  and 
reported  in  1893.a  In  his  report  37  faunules  are  analyzed  and  the 
species  tabulated.  The  number  of  species  positively  determined  is 
66;  18  more  species  are  named,  but  marked  with  a  query,  and  13  gen- 
eric names  are  cited  without  identification  of  the  species  observed. 
The  12  more  common  species  of  the  37  faunules  are  named  in 
Table  VI. 

of  the  Hamilton  formation 


Table  VI.  —  Tropidoleptus  fauna:  Dominant 

of  the  Unadilla  region. 


*  1 .  Ambocoelia  umbonata  . 23 

*2.  Tropidoleptus  carinatus ..  20 

Spirifer  pennatus 17 

Paracyclas  lirata 11 

Leiorhynchus  laura _ .  10 

*  6.  Nuculites  oblongatus 13 


*3 
4 
5 


7.  N.  triqueter 9 

8.  Chonetes  coronatus 9 

9.  Spirifer  granulosus ._ .  7 

10.  Palaeoneilo  constricta 7 

11.  Spirifer  medialis 7 

12.  Chonetes  scitulus 7 


species  belong  to  the  standard 


It  will  be  noted  that  8  of  these  12 
dominant  list  of  12  (Table  V),  compiled  from  the  various  statistics  of 
the  State.     They  are  marked  with  asterisks  before  the  names. 

The  species  of  the  standard  list  which  are  not  among  the  first  12 
species  of  the  Unadilla  list  are — 

Phacops  rana. 
Athyris  spiriferoides. 
Nucula  corbulif  oralis . 
N.  bellistriata. 

The  dominant  list  for  the  Unadilla  district  contains  four  species  not 
in  the  general  dominant  list,  which  are — 

Paracyclas  lirata. 
Leiorhynchns  laura. 
Spirifer  medialis. 
Chonetes  scitulus. 


a  Forty-sixth  Ann.  Rept.  New  York  State  Museum,  1893,  pp.  256-288. 


WILLIAMS.] 


FAUNAL    DISSECTION    OF    THE    DEVONIAN. 


63 


If  now  we  make  a  revised  list  by  adding  to  the  standard  list  based 
on  the  146  faunules  the  new  distributional  values  of  all  the  species  as 
they  appear  in  the  37  TTnadilla  faunules,  they  will  then  stand  as  in 
Table  VII,  the  numbers  at  the  right  expressing  the  distributional 
values  of  the  species  in  the  146  +  37=183  faunules. 

Table  VII. — Tropidoleptus  fauna:  Revised  list  of  dominant  species  of  the  Ham- 
ilton formation  of  eastern  New  York  and  Pennsylvania,  as  expressed  in  183 
faunules. 


1.  Spirifer  pennatus 130 

2.  Tropidoleptus  carinatus 109 

3.  Spirifer  granulosus 66 

4.  Chonetes  coronatus 65 

5.  Amboccelia  umbonata.        63 

6.  Palaeoneilo  constricta  . . .         . . .  63 

7.  Nuculites  oblongatus  .     48 

8.  N.  triqueter 47 


9.  Nucula  bellistriata  _  _   47 

10.  Phacops  rana 38 

11 .  Athyris  spiriferoides .  _ .  36 

12.  Nucula  corbuliformis ...  33 

13.  Leiorhynchus  laura  -  _         30 

14.  Paracyclas  lirata .  29 

15.  Chonetes  scitulus . ._  24 

16.  Stropheodonta  perpiana  _  _ . 21 


It  will  be  observed  that  the  first  12  species  of  this  table  are  the 
same  as  the  12  species  in  the  standard  list  (Table  V),  and  that  none 
of  the  4  species  which  were  specially  dominant  only  in  the  Unadilla 
list  reach  as  high  distributional  value  as  do  all  of  those  of  the  stand- 
ard list.  The  new  facts  brought  in  by  the  additional  statistics  derived 
from  the  same  general  region  do  not  disturb  the  general  results 
obtained  by  consideration  of  the  smaller  number  of  faunules. 

STATISTICS  BASED   ON  ANALYSIS  OF  THE   ZONES  OF  THE 
LIVONIA  SALT   SHAFT. 

The  faunules  discussed  b}^  Prosser  in  his  paper  on  eastern  New  York 
and  Pennsylvania  under  the  designation  of  Hamilton  do  not  definitely 
include  the  Marcellus.  The  list  of  faunules  reported  by  Cleland  from 
Cayuga  Lake  begins  with  the  Marcellus.  Mr.  Grabau's  analyses  of 
the  Hamilton  group  of  Eighteenmile  Creek  take  in  the  transition  zone 
of  the  top  of  the  Marcellus.  The  conclusions,  therefore,  reached  from 
study  of  the  statistics  reported  by  these  men  deal  with  the  pure  Ham- 
ilton fauna. 

•Dr.  Clarke  has  given  an  analysis  of  the  species  discovered  in  the 
Livonia  salt  shaft, a  which  runs  lower  than  the  other  records,  taking 
in  the  Marcellus  and  Onondaga  faunas.  In  his  list  for  the  part  of 
the  record  covering  the  Hamilton  formation,  all  the  abundant  species 
of  the  other  lists  are  reported,  with  the  exception  of  Nucula  corbuli- 
formis, but  the  frequency  of  records  in  the  separate  faunule  lists  is 
not  so  emphatically  expressed  as  in  the  lists  formed  with  the  definite 
purpose  of  recording  frequency  values  with  precision.  Dr.  Clarke 
separates  the  series  above  the  Marcellus  into  10  zones,  but  the  recorded 
species  reach,  in  the  highest  case,  only  10/16  of  frequency  value.  This 
is  the  case  of  Phacops  rana,  which  is  recorded  ten  times. 


a  The  succession  of  the  fossil  faunas  in  the  section  of  the  Livonia  salt  shaft,  by  John  M,  Clarke: 
Thirteenth  Ann.  Rept.  State  Geologist  New  York,  1893,  Vol.  I,  Geology,  pp.  131-158, 


64 


CORRELATION    OF    GEOLOGICAL    FAUNAS. 


[BULL.  210. 


The  species  occurringthe  greater  number  of  times  in  the  10  faunules 
reported  are  as  follows : 

Table  VIII. — Tropidoleptus  fauna:  List  of  species  appearing  most  frequently 
in  the  16  zones  of  the  Hamilton  formation  of  the  Livonia  salt  shaft. 


*1.  Phacops  rana 10 

2.  Diaphorostoma  lineatum ...  _  8 

3.  Orthoceras  nuntium 7 

4.  Chonetes  scitulus 7 

5.  Orthis  vanuxemi 7 

6.  Orthothetes  arctistriatus 6 

7.  Productella  spinulicosta 6 


H) 


8.  Bellerophon  leda 

9.  Actinopteria  decussata 
Streptelasma  rectum  . . 


*11 .  Spirifer  pennatus 5 

12.  Orbiculoidea  media 5 

*13.  Chonetes  coronatus 5 

*14.  Ambocoslia  umbonata 5 


Those  of  the  standard  list  are  marked  with  asterisks,  and  consti- 
tute only  4  of  the  list  of  14,  and  only  1  of  those  among  the  first  10. 
The  other  species  of  the  Livonia  list  (with  the  exception  of  the  sec- 
ond) are,  however,  all  reported  from  rocks  of  the  Hamilton  formation 
in  the  East.  The  high  range  value  assigned  to  species  in  the  Livonia 
section,  which  take  a  relatively  less  conspicuous  place  in  both  the 
Cayuga  Lake  and  the  Eighteenmile  Creek  sections,  may  be  explained 
on  the  supposition  that  the  author  gave  closer  attention  to  the  species 
by  which  the  several  zones  can  be  distinguished  than  to  those  com- 
mon species  which  appear  most  frequently  throughout  the  series. 
Otherwise  it  is  necessary  to  assume  from  the  records  that  the  common 
species  appear  less  frequently  in  the  zones  of  the  Livonia  section 
than  would  be  expected  from  all  the  other  statistics  which  were  gath- 
ered specially  to  ascertain  the  range  and  distributional  values. 

HAMILTON   FORMATION   IN   ONTARIO,   CANADA. 

The  species  of  the  Hamilton  formation  of  Ontario,  Canada,  as 
reported  by  Dr.  Whiteaves/'  include  8  of  the  standard  list  of  12  dom- 
inant species  of  the  Tropidoleptus  fauna,  and  several  of  those  quoted 
as  more  or  less  dominant  not  among  the  first  12. 

The  list  of  species  is  given  in  Table  IX.  They  are  arranged  alpha- 
betically, because  the  statistics  regarding  range  or  distributional  fre- 
quency are  not  reported. 

Table  IX. — Tropidoleptus  fauna:  Species  of  the  standard  lists  of  the  Hamilton 
formation  of  NewYork  State  which  are  also  reported  from  the  Hamilton  for- 
mation of  Ontario,  Canada. 

*  Ambocoslia  umbonata.  Orthothetes  arctistriatus. 

*  Athyris  spiriferoides.  *  Phacops  rana. 

*  Chonetes  coronatus.  Primitiopsis  punctilifera. 
C.  lepidus.  •  Rhipidomella  vanuxemi. 
C.  scitulus.                                                       *  Spirifer  granulosus. 

.     Cryphaeus  boothi.  *S.  (mucronatus)  pennatus. 

*  Nuculites  triqueter.  *  Tropidoleptus  carinatus. 

a  On  some  additional  or  imperfectly  understood  fossils  from  the  Hamilton  formation  of  Onta- 
rio, with  a  revised  list  of  the  species  therefrom,  Ly  J.  F.  Whiteaves:  Contributions  to  Canadian 
Palaeontology,  1885-1898,  Vol.  I,  Part  V,  pp.  361-436,  Pis.  XLVIII-L. 


williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  65 

The  four  species  absent  are — 

Nucula  bellistriata.  Nuculites  oblongatus. 

N.  corbuliformis.  Palseoneilo  constricta. 

The  naming  of  these  species  at  once  calls  attention  to  the  fact  that 
these  species  and  the  genera  to  which  they  belong  hold  conspicuously 
a  more  important  place  in  the  fauna  of  the  Hamilton  formation  of 
the  eastern  portion  of  the  State  of  New  York  than  in  the  western 
half.  This  remark  applies  also  to  the  Pelecypoda  in  general.  On 
the  other  hand,  the  fauna  is  richer  in  Coelenterata  in  Ontario  than 
in  its  more  eastern  expression. 

HAMILTON   FORMATION   IN   MICHIGAN. 

The  faunal  lists  for  the  Hamilton  formation  of  the  Michigan  area 
are  still  imperfect,  but  some  idea  of  the  common  species  may  be  gath- 
ered from  the  lists  prepared  by  C.  Rominger.a 

The  occurrence  of  the  following  species  is  mentioned: 

Spirifer  (mucronatus)  pennatus. 

S.  granulosus. 

Chonetes  coronatus. 

(Spirigera  concentrica^=)  Athyris  spiriferoides. 

(Phacops  bufo=)  P.  rana. 

Other  species  of  the  Tropidoleptus  fauna  are  recorded,  but  the  above 
mentioned  constitute  5  of  the  10  species  of  the  standard  list. 

The  recent  investigation  of  the  faunas  in  northern  Michigan  made 
by  Mr.  Grabau6  does  not  increase  the  number  of  species  of  the  domi- 
nant list. 

HAMILTON   FORMATION   IN   WISCONSIN. 

The  Milwaukee  fauna  analyzed  by  Messrs.  Teller  and  Monroec 
contains  the  following  species: 

Phacops  rana. 
Palseoneilo  constricta. 
Nucula  corbuliformis. 
Spirifer  pennatus. 

Several  other  species  of  the  common  fauna  of  the  Hamilton  forma- 
tion of  eastern  New  York  are  also  reported. 

Here  are  enough  of  the  representatives  of  the  standard  Tropidolep- 
tus  carinatus  fauna  to  lead  to  the  inference  that  the  typical  fauna  is 
not  far  distant,  but  whether  the  separation  is  geographical  or  strati- 


« Geological  Survey  of  Michigan,  1873-1876,  Vol.  Ill,  pp  38-63. 

''Stratigraphy  of  the  Traverse  group  of  Michigan, by  A.  W.  Grabau;  Rept.  State  Board  of 
Geol   Surv.  Mich.,  for  1901-2. 

«The  fauna  of  the  Devonian  formation  at  Milwaukee,  Wis.:  Jour.  Geol.,  Vol.  VII,  1899,  pp. 
272-283. 

Bull.  210—03 5 


66  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

graphical  is  not  evident  from  the  citation  of  these  species  alone.  The 
presumption  is  that  the  strata  at  Milwaukee  constitute  an  extension 
of  the  Hamilton  formation  of  the  lower  peninsula  of  Michigan.  The 
problem  of  determining  the  correlation  of  the  fauna  can  be  discussed 
more  satisfactorily  after  the  facts  regarding  the  relations  of  the 
various  faunas  in  the  New  York-Pennsylvania  subprovince  to  one 
another  are  elaborated. 

HAMILTON  FORMATION  IN  SOUTHERN   ILLINOIS. 

In  southern  Illinois  occurs  a  fauna,  analyzed  by  Prof.  Stuart  Weller,a 
which  contains  three  of  the  standard  representatives  of  the  Tropido- 
leptus fauna,  viz: 

Chonetes  coronatus. 
Phacops  rana. 
Tropidoleptus. 

Some  of  the  less  common  species  of  the  New  York  Hamilton  fornia- 
tion  arc  also  reported  in  the  list. 

The  species  enumerated  constitute  characteristic  species  of  the 
Tropidoleptus  carinatus  fauna,  and,  although  few,  they  seem  to  leave 
no  doubt  as  to  the  presence  of  the  fauna.  But  we  are  still  left  in 
doubt  whether  this  faunule  may  not  represent  actually  an  earlier 
geological  horizon  than  the  base  of  the  typical  Hamilton  formation  in 
New  York. 

The  association  of  these  species  with  species  which  do  not  appear 
in  the  typical  Hamilton  formation  in  New  York  confirms  the  opinion, 
derived  from  a  comparison  of  the  fauna  with  those  outside  the  basin, 
that  the  Tropidoleptus  fauna  as  a  whole  came  into  this  interconti- 
nental basin  from  the  south,  and  probably  by  a  passage  on  the  south 
side  of  the  Ozark  island  of  Missouri.  If  this  hypothesis  be  correct, 
the  association  of  the  more  typical  species  of  the  fauna  with  Onon- 
daga species  in  the  southwest  corner  of  the  basin  is  not  unexpected. 
The  facts  regarding  the  association  of  species  in  the  faunules  along 
the  western  side  of  the  Cincinnati-Nashville  axis,  in  Kentucky,  Indi- 
ana, and  Ohio,  point  the  same  way. 

SELLERSBURG    FORMATION    IN    INDIANA. 

Recent  investigation  made  by  Dr.  E.  M.  Kindle  is  revealing  traces 
of  the  Tropidoleptus  fauna  to  the  west  of  the  Cincinnati-Nashville 
ridge  in  central  Indiana. 

In  a  report  now  preparing  for  the  press,  Dr.  Kindle  gives  the  fol- 
lowing list  of  species  occurring  in  a  Sellersburg  faunule  from  a  section 
in  the  town  of  Lexington,  Scott  County,  a  few  miles  north  of 
Louisville,  Ky. 


«  Correlation  of  the  Devonian  faunas  in  southern  Illinois:  Jour.  Geol.,  Vol.  V,  1897,  pp.  625  635- 


williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  67 

Sellersburg  faunule,  Lexington,  Scott  County,  Ind. 
Chonetes  yandellanus  (abundant). 
Tropidoleptus  carinatus  (abundant). 
Spirifer  granulosus  (common). 
Stropheodonta  demissa  (common). 
Roemerella  grandis  (rare) . 
Phacops  rana  (rare) . 
Proetus  canaliculatus. 
Stictopora  sp.  ? 
Cystiphyllum  sp.  ? 

Other  sections  of  the  same  formation  (Sellersburg)  contain  Spirifer 
pennatus,  Spirifer  granulosus,  Stropheodonta  perplana,  and  other 
species  of  the  Tropidoleptus  fauna.  Several  other  faunules  reported 
from  the  southern  part  of  the  district  contain  Tropidoleptus;  in  this 
faunule  it  is  abundant. 

As  far  north  as  Cass  County  traces  of  the  same  fauna  are  detected 
in  the  beds  overlying  the  Jefferson ville  limestone  and  underlying  the 
New  Albany  black  shales. 

Although  these  facts  point  to  the  presence  of  representatives  of  the 
Tropidoleptus  carinatus  fauna  in  the  formation  west  of  the  ridge,  it 
does  not  necessarily  follow  that  the  Sellersburg  is  the  stratigraphical 
equivalent  of  the  Hamilton  formation  of  New  York,  since,  as  will  be 
shown,  the  dominant  as  well  as  a  large  number  of  the  ordinary 
species  of  that  fauna  appear  in  the  Ithaca  formation,  known  to  be, 
geologically,  of  later  age  than  the  Hamilton  formation. 

The  fuller  discussion  of  the  questions  here  raised  will  appropriately 
come  after  the  main  problem  is  presented  and  elaborated,  and  the 
laws  of  shifting  of  faunas  established  by  evidence. 

There  will  be  no  objection,  I  think,  to  the  claim  that  these  several 
local  faunules  belong  to  the  same  general  Tropidoleptus  fauna;  but  the 
formational  equivalency  may  be  questioned,  as  will  be  brought  out 
as  Ave  proceed  to  the  discussion  of  the  fauna  of  the  formations 
following  the  Hamilton  in  the  eastern  New  York  area. 

ROMNEY  FORMATION    IN   WESTERN    MARYLAND. 

Through  the  courtesy  of  the  State  geologist  of  Maryland,  Prof.  W.  B. 
Clark,  and  of  Prof.  C.  S.  Prosser,  the  paleontologist,  I  am  able  to  con- 
sult the  faunule  list  of  species  from  the  Romney  formation  of  western 
Maryland,  recently  secured  under  the  auspices  of  the  Maryland 
geological  survey. 

In  the  list  furnished  me  by  Professor  Prosser  there  appear  132 
entries,  91  of  which  are  positive  specific  identifications.  Among  the 
latter  are  found  all  of  the  dominant  species  of  the  Tropidoleptus 
carinatus  fauna,  as  estimated  from  the  New  York  statistics  (see  Table 
V).  This  is  sufficient  to  establish  the  extension  of  the  Tropidoleptus 
fauna,  in  its  integrity,  as  far  south  in  the  Appalachian  trough  as 
Maryland. 


68  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

ABSENCE  OF  TROPIDOLEPTUS  FAUNA  IN   OTHER  REGIONS. 

That  the  Tropidoleptus  fauna  is  not  represented  in  the  Iowa  forma- 
tions is  signified  by  the  fact  that  only  Phacops  rana  of  the  standard 
list — a  species  of  very  wide  geographical  range — appears  in  the  lists 
consulted. 

The  Manitoba,  Saskatchewan,  and  Mackenzie  River  lists  prepared 
by  Dr.  Whiteaves  do  not  record  a  single  species  of  the  standard  Tropi- 
doleptus carinatus  faunal  list. 

We  are  thus  led  to  the  separation  of  the  Devonian  faunas  of  Iowa 
and  the  Northwest  (outside  the  intercontinental  basin)  from  those  of 
the  Appalachian  province  and  its  extensions,  both  into  the  Tennessee 
province  and  into  the  Michigan  province,  with  the  latter  of  which, 
faunally,  the  Milwaukee  localit}^  must  be  regarded  as  directly  con- 
nected. 

POST- HAMILTON     FORMATIONS    AND     THEIR    FAUNAS     IN     NEW 

YORK  PROVINCE. 

Having  demonstrated  the  dominant  characteristics  of  the  fauna 
which  is  contained  in  the  Hamilton  formation  in  its  central  position 
and  where  the  facts  are  most  fully  known,  we  have  next  to  consider 
the  faunal  characteristics  of  the  overlying  formations.  The  upper 
termination  of  the  Hamilton  was,  for  the  purposes  of  this  investigation, 
assumed  to  be  at  the  bottom  of  the  Tully  limestone,  where  that  is 
present;  at  the  bottom  of  the  black  Genesee  shale,  where  that  is  clear 
and  the  Tully  is  not  evident;  and,  where  the  evidence  of  those  ordi- 
narily overlying  formations  is  indistinct,  at  the  place  in  the  sequence 
of  strata  which  can  be  definitely  traced,  by  either  stratigraphical  or 
paleontological  evidence,  as  the  stratigraphical  extension  of  that  plane. 

It  is  also  taken  for  granted  that  the  list  of  species  given  in  Table  V 
may  be  relied  upon  as  positive  evidence  of  the  Tropidoleptus  carinatus 
fauna  as  it  is  expressed  in  the  northeastern  corner  of  the  continental, 
basin  of  North  America.  The  entire  absence  from  any  fossil  faunule 
of  the  12  species  there  enumerated  may  be  regarded  as  presumptive 
evidence  that  the  Tropidoleptus  fauna  is  absent,  although  other  species 
among  the  200  or  more  thereof  known  to  be  and  found  associated  with 
them  might  be  present. 

On  the  other  hand,  the  presence  of  the  majority  of  these  dominant 
species  is  not  proof  positive  that  we  are  dealing  with  the  stratigraphical 
equivalent  of  the  Hamilton  formation,  for  the  two  following  reasons- 
First,  the  fauna  may  have  migrated  into  the  region  in  which  the  Ham- 
ilton formation  was  deposited,  in  which  case  the  fauna  existed  prior  to 
the  beginning  of  that  formation;  second,  unless  evidence  can  be  fur- 
nished of  the  destruction  of  the  fauna  at  the  time  of  the  deposition 
of  the  Tully  limestone  or  the  Genesee  shale,  there  is  no  reason  to 
believe  that  its  integrity  as  a  fauna  was  there  suddenly  lost.  But  we 
may  assume  that  evidence  of  lessening  bionic  value  of  these  species,  as 
indicated  by  their  loss  of  dominance  in  the  local  or  temporary  faunules 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  69 

in  which  the}'  occur,  may  be  interpreted  as  indicating  modification 
of  the  fauna  as  a  whole,  due  either  to  lapse  of  time  in  the  same  region, 
resulting  in  the  loss  of  supremacy  of  these  species,  or  to  shifting  of 
the  fauna  as  a  whole,  resulting  in  loss  of  life  and  change  in  the 
equilibrium  of  the  species  owing  to  change  of  conditions  of  life. 

It  will  be  remembered  that  in  the  section  running  through  Cayuga 
Lake  and  Ithaca,  which  was  elaborated  in  1883,a  both  the  Tully  lime- 
stone and  the  Genesee  shales  are  distinct  formations  and  form  a 
definite  termination  for  the  Hamilton  formation. 

It  was  pointed  out  in  a  later  paper  h  that  this  zone  was  indicated  by 
the  first  appearance  in  the  New  York  section  of  Rhy  nchonella  (Hypo- 
thyris)  cuboides  (=R.  venustula  Hall)  and  other  species  not  found 
below  in  the  Hamilton,  but  widely  distributed  in  other  parts  of 
the  world.  The  inference  was  drawn  that  there  had  been  modifica- 
tion of  the  local  fauna  by  immigration  of  foreign  elements.  The 
fauna  to  which  these  immigrants  belonged  in  other  regions  was 
observed  to  be  more  intimately  associated  with  the  later  faunas  of 
the  New  York  region  (the  Spirifer  disjunctus  fauna)  than  with  the 
Tropidoleptus  fauna,  and  the  conclusion  was  therefore  reached  that 
the  Tully  limestone  was  more  naturally  associated  faunally  with  the 
formations  that  stratigraphically  follow  it  than  with  the  Tropidoleptus 
carinatus  fauna  of  the  Hamilton,  and  so,  in  spite  of  the  survival  of 
many  species  of  the  underlying  formation,  the  fauna  of  the  Tully 
limestone  was  appropriately  called  the  cuboides  fauna,  from  the 
dominance  of  this  new  form,  Rhynchonella  cuboides. 

In  the  more  exact  nomenclature  adopted  in  writing  this  paper  the 
cuboides  fauna  may  be  regarded  as  only  a  faunule — that  is,  only  a 
local  and  temporary  representative  of  a  fauna  which,  though  not 
widely  represented  in  the  interior  continental  basin  of  North  America, 
probably  had  its  fuller  characteristics  expressed  in  the  outer  Manitoba- 
Mackenzie  River  seas  of  Devonian  time. 

In  the  Cayuga  Lake-Ithaca  section,  above  the  Tulty  came  the  black 
Genesee  shale  with  its  Lingula  spatidata  faunule. e  This  faunule 
contains  Amboccdia  umbonata,  but  no  other  one  of  the  12  dominant 
species  of  the  Tropidoleptus  fauna.  Following  this  was  a  small 
faunule  which  is  related  to  the  Portage  fauna  of  the  Genesee  Valley, 
as  seen  by  the  continued  presence  of  Cardiola  speciosa; (l  and  above 
that  came  the  Spirifer  Ice/vis  faunule,  still  a  modification  of  the  western 
Cardiola  (Portage)  fauna/  but  mingled  with  some  of  the  species  of 
the  Tropidoleptus  fauna.  Still  a  third  modification  of  the  Cardiola 
fauna  is  seen  in  some  black  or  dark  shales  above  the  Spirifer  l&vis 

«Onthe  fossil  faunas  of  the  Upper  Devonian  along  the  meridian  of  76°  307  from  Tompkins 
County,  N.  Y.,  to  Bradford  County,  Pa.,  by  H.  S.  Williams:  Bull.  U.  S.  Geol.  Survey  No.  3. 

?>Tho  Cuboides  zone  and  its  fauna;  a  discussion  of  methods  of  correlation,  by  H.  S.  Williams: 
Bull.  Geol.  Soc.  Am.,  Vol.  I,  pp.  481-501,  Pis.  XI-XIII. 

(•Bull.  U.  S.  Geol.  Survey  No.  3,  p.  9. 

d  Ibid.,  p.  11. 

<-Ibid.,  p.  12. 


70  COREELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210.  • 

zone.a  A  few  feet  higher,  in  the  lower  part  of  the  rocks  outcropping 
in  the  Cascadilla  Creek  gorge,6  a  faunule  was  discovered  in  which 
occurred  several  well-known  Hamilton  species,  among  them — 

Spirifer  fimbriatus. 
Pleurotomaria  capillaria. 
Ambocoelia  umbonata. 
Modiomorpha  complanata. 

Of  these  only  Ambocoelia  belongs  to  the  dominant  Tropidoleptus 
faunal  list. 

Above  all  these  appears  the  typical  Ithaca  fauna,  which  now  may 
be  called  the  Productella,  speciosa  fauna,  from  the  species  of  Produc- 
tella  which  is  characteristic  of  this  horizon  in  a  number  of  stations 
examined  and  does  not  appear  to  have  occurred  earlier,  while  higher 
up  it  is  represented  by  such  forms  as  Productella  lachrymosa  and 
its  varieties.  The  "Spirifer  mesicostalis"  associated  with  it  in  the 
fauna  at  Ithaca c  was,  at  the  time  of  writing  the  report,  regarded  as 
an  early  form  of  the  species  so  named,  then  regarded  as  a  Chemung 
species.  This  common  Ithaca  form  is  now  called  Spirifer  pennatus 
var.  poster  us. d 

In  the  report''  quoted  I  called  attention  to  the  fact  that  the  Ithaca 
fauna,  with  this  Spirifer  as  a  characteristic,  occurred  below  the 
Chemung  and  was  a  fauna  more  closely  related  to  the  Hamilton  than 
to  the  Chemung: 

This  fauna  is  the  regular  successor  of  the  Hamilton  fauna,  and  is  intermediate 
between  it  and  that  of  the  Chemung  group.  It  appears  to  have  come  in  from  the 
east.  It  prevailed  during  the  deposition  of  two  to  three  hundred  feet  of  arena- 
ceous shales;  the  coral  sandstone  fauna  came  in  before  its  maximum  development. 
At  the  close  of  its  occupation  of  this  area  a  dark,  fissile  shale  with  a  Discina 
fauna  came  in.  This  I  believe  to  be  another  outlier  of  the  Genesee  shale  condi- 
tions, whose  center  at  this  time  must  have  been  toward  the  western  part  of  the 
State. 

Since  writing  that  report  the  new  facts  regarding  the  range  of 
species  east  of  the  Cayuga  Lake  meridian  have  led  to  a  recognition  of 
the  actual  presence  of  a  large  part  of  the  Tropidoleptus  carinatus  fauna 
in  the  sediments  farther  east,  which  are  shown  to  be  the  stratigraphical 
equivalents  of  these  beds  at  Ithaca.  This  fact  establishes  the  varia- 
tional nature  of  the  differences  marking  many  of  the  Ithaca  forms 
when  compared  with  typical  Hamilton  species.  Sufficient  facts  are 
present  to  show  a  gradation  from  typical  Spirifer  (rnucronatus)  pen- 
natus of  the  eastern  counties  to  Spirifer  pennatus  var.  posterusf 
of  this  western  extension,  and  many  of  the  species  going  under  the 
same  names   show  some  local    peculiarities  which  are    sufficient  to 

« Bull.  U.  S.  Geol.  Survey  No.  3,  p.  14. 

Moid.,  p.  15. 

clbid.,  p.  17. 

d Palaeontology  New  York,  Vol.  VIII,  Part  II,  p.  36,  pi.  34,  189.5. 

eBull.  U.  S.  Geol.  Survey  No.  3,  p.  30. 

/Palaeontology  New  York,  Vol.  VIII,  Part  II,  p.  361,  figs.  27-31,  PI.  XXXIV. 


wilmams]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  71 

enable  one  familiar  with  the  fossils  to  distinguish  the  Ithaca  varieties 
from  the  typical  Hamilton  species. 

FAUNA  OF  EASTERN  EXTENSION  OF  PORTAGE  FORMATION. 

The  identification  of  the  Portage  formation  in  eastern  New  York 
and  Pennsylvania  is  fairly  satisfactory  in  case  the  identification  refers 
to  a  recognition  of  the  formation  in  its  eastern  extension,  irrespective 
of  exact  equivalency  of  faunas  or  likeness  of  sediments.  But  in  the 
eastern  counties  neither  is  it  stratigraphically  clearly  to  be  distin- 
guished from  lower  or  higher  strata,  nor  does  it  contain  in  its  fauna 
any  characteristic  species  of  the  Ithaca  expression  of  the  lower  Port- 
age formation.  Nevertheless,  the  identification  of  the  strata  as  the 
outcroppings  of  the  same  rocks  which  farther  west  are  distinguished, 
both  lithologically  and  paleontologically,  as  lower  Portage  is  well 
demonstrated ;  and  the  assignment  on  a  geological  map  of  the  Portage 
color  to  the  region  from  which  the  15  reported  faun  ales  came  is 
defensible,  if  it  be  granted  that  the  same  formation  name  may  be 
applied  to  strata  of  which  the  contemporaneous  sedimentation  can  be 
established,  although  their  lithological  and  paleontological  characters 
are  different. 

I  take  this  case  from  the  region  holding  the  typical  Hamilton  for- 
mation, with  its  Tropidoleptus  carinatus  fauna,  to  illustrate  a  phase 
of  a  fauna  which  is,  without  question,  directly  descended  from  the 
typical  Tropidoleptus  fauna,  but  is  certainly  younger. 

How  is  such  a  fauna  distinguished? 

(1)  The  great  majority  of  its  species  are  the  same  as  those  of  the 
typical  Tropidoleptus  carinatus  fauna  below. 

(2)  The  few  distinctive  species  never  appear  at  the  lower  horizon, 
but  they  are  frequent  above,  and  first  appear  at  a  like  horizon  over 
considerable  area;  and 

(3)  They  are  more  prominent  in  frequency  of  individuals  where  the 
characteristic  species  of  the  Tropidoleptus  carinatus  fauna  are  deficient. 

In  the  15  faunule  lists  of  this  group  given  by  Prosser,  41  species  are 
positively  identified. 

Of  these  41  species,  34  are  recurrent  species,  and  among  the  domi- 
nant species  of  the  Portage  fauna  occur  five  species  and  two  varie- 
ties of  the  Tropidoleptus  fauna. 

Of  the  standard  Tropidoleptus  carinatus  list,  six  species  are  reported 
the  number  of  times,  out  of  a  possible  15  localities,  indicated  by  the 
figures  in  the  following  list: 
Table  X.—Becurren  t  species  of  the  Tropidoleptus  fauna  in  the  Portage  formal  ion . 

Tropidoleptus  carinatus  - -  8 

Nucula  corbulif ormis - -  3 

Pala?oneilo  constricta 3 

Nuculites  oblongatus '•> 

Phacops  rana -  - - -  -  - - 1 

Spirifer  (mucronatus)  pennatus - -  -  - - 1 


72  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

The  form  Spirifer  pennatus  var.  posterns  is  reported  eight  times, 
thus  indicating  the  unmistakable  mutation  of  "pennatus"  into  the 
new  variety. 

Below  is  the  list  of  forms  characteristic  of  the  Portage  formation : 

Table  XI. — Characteristic  Portage  species. 

1 .  Spirifer  pennatus  var.  posterns  ( =  S.  mesicostalis,  first  var. ) 8 

2.  Spirifer  mesistrialis . 7 

3.  Modiomorpha  subalata  var.  chemungensis .  _  _ . 6 

4.  Leiorhynchus  mesicostale . . .  6 

5.  Rhynchonella  stephani 4 

6.  Prothyris  lanceolata  .   . .    . . 2 

7.  Palaeoneilo  filosa . . .  1 

Putting  these  two  lists  together,  it  will  be  seen  that  the  character- 
istic Portage  species  dominate  over  the  recurrent  Hamilton  species  of 
the  older  fauna.  Tropidoleptus  still  retains  its  conspicuous  place  in 
the  fauna,  its  bionic  value  being  eight-fifteenths,  or  50  per  cent.  In 
the  Ithaca  region  this  species  does  not  occur  in  the  Portage  forma- 
tion, but  all  the  above  characteristic  species  are  present,  and  have 
high  bionic  values,  with  the  exception  of  Prothyris  lanceolata,  which 
is  a  rare  form. 

The  dominant  species  of  the  fauna  of  the  Portage  zone  in  the  east- 
ern counties  at  15  localities,  Avith  their  approximate  bionic  values,  are 
shown  in  the  following  table: 

Table  XII. — Dominant  species  of  the  Portage  zone  in  eastern  New  York. 

1 .  Paracyclas  lirata 12 

2.  Tropidoleptus  carinatus 8 

3.  Spirifer  pennatus  var.  posterus 8 

4.  Actinopteria  boydi _  8 

5.  Spirifer  mesistrialis 7 

6.  Palaeoneilo  emarginata 7 

7.  Leiorhynchus  mesicostale 6 

8.  Modiomorpha  subalata  var.  chemungensis 6 

9.  Leda  diversa 6 

10.  Chonetes  setigerus  .  _ .  5 

11 .  Rhynchonella  stephani .  _  .■ 4 

Study  of  these  lists  shows  that  this  fauna  of  the  Portage  zone  in  the 
eastern  counties  is  still  strong  in  recurrent  species  of  the  typical 
Hamilton  formation  of  that  region,  viz,  the  Tropidoleptus  fauna,  so 
that  the  former  might  be  called  the  Posterus  subfauna  of  the  Tropido- 
leptus fauna;  still  it  has  characteristics  of  its  own,  clearly  indicating 
its  later  age  and  its  equivalency  with  the  more  distinct  lower  Portage 
fauna  of  Ithaca. 

These  characteristics  may  be  formulated  in  the  following  way: 
(1)  The  majority  of  the  species  (34  out  of  a  total  41   listed)  are 
recurrent  species. 


\'. 


Williams.]  FAUNAL    DISSECTION    OF   THE    DEVONIAN.  73 

(2)  Its  dominant  list  of  11  species  includes  but  one  of  the  dominant 
list  of  the  Hamilton  formation. 

(3)  In  the  dominant  list  occur  five  characteristic  species  not  found 
in  the  formations  below,  and  two  of  the  five  are  recognized  mutants 
of  earlier  species. 


'.-,' 


FAUNA     OF     ITHACA     FORMATION     AS     EXPRESSED     IN     THE     TYPICAL 
LOCALITY   AT  ITHACA,    N.    Y. 

In  the  bulletin  referred  toa  the  faunas  directly  following  the  Gene- 
see shale  in  the  Ithaca  region  were  fully  analyzed  into  distinct  sub- 
faunas,  and  in  later  papers  the  extension  of  these  subfaunas  to  their 
prevalent  common  faunas  to  the  east  and  west  was  traced.  The 
recurrence  of  Hamilton  species  was  also  there  distinctly  recog- 
nized in  a  small  faunule  occurring  in  the  lower  part  of  the  Cascadilla 
Creek  gorge  (station  No.  14  N.).  The  Universit}^  quarry  (station  5) 
and  the  "inclined  plane"  section  on  South  Hill  and  outcrops  in  Fall 
Creek  and  Cascadilla  Creek  were  examined,  and  the  lists  of  species 
were  reported  at  that  time  as  containing  the  typical  "Ithaca  fauna." 
After  the  publication  (1884)  of  the  bulletin  many  additional  species 
were  collected  by  my  students  and  myself,  which  were  added  to  the 
collections  in  Cornell  University.  Some  twelve  years  later  Dr.  E.  M. 
Kindle  (then  a  student  in  Cornell  Universit}^)  made  an  exhaustive 
study  of  the  Ithaca  fauna,  and  to  illustrate  this  particular  fauna  put 
together  in  a  valuable  memoir  all  the  statistics  then  in  hand.  This 
was  published  in  1896,6  and  for  the  purpose  of  the  present  discussion 
this  paper  by  Dr.  Kindle  contains  by  far  the  best  set  of  statistics  in 
sight. 

Ten  sections  within  a  few  miles  of  the  head  of  Cayuga  Lake,  situ- 
ated in  the  town  of  Ithaca  and  in  the  immediate  neighborhood,  fur- 
nish the  statistics.  The  number  of  stations  is  54.  These  range 
through  a  thickness  of  260  feet  stratigraphically.  I  have  tabulated 
the  species  for  the  purpose  of  determining  their  relative  values  in 
relation  to  frequency  of  discovery  in  the  54  stations  examined. 

In  all  the  collections  gathered,  84  species  were  positively  identified, 
specifically,  by  Dr.  Kindle.  Of  the  species  so  recognized,  33  arc 
reported  also  from  the  Hamilton  of  the  eastern  counties  (Prosser), 
and  31  from  the  underlying  Hamilton  of  the  Cayuga  Lake  section 
(Cleland). 

The  stations  are  not  uniformly  distributed  through  the  sections, 
and  some  of  the  sections  contain  over  ten  stations,  while  others  con- 
tain but  two  or  three.  They  are  the  chief  fossiliferous  outcrops  of  1  he 
region,  presented  by  ravines,  quarries,  and  occasional  outcrops  on  the 
steep  hillsides  about  Ithaca.  They  do  not,  however,  present  as  com- 
et Bull.  U.  S.  Geol.  Survey  No.  3. 

?>The  relation  of  the  fauna  of  the  Ithaca  group  to  the  fauna  of  the  Portage  and  Chemung,  by 
Edward  M.  Kindle:  Bull.  Am.  Pal.,  No.  6,  Dec.  25,  L896.    Ithaca. 


74  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

plete  and  thorough  an  analysis  of  the  faunal  contents  of  the  Ithaca 
formation  as  we  have  of  the  Hamilton  formation  in  Mr.  Grabau's 
analysis  of  Eighteenmile  Creek,  or  in  Dr.  Cleland's  analysis  of  the 
Cayuga  Lake  section.  In  both  of  the  latter  cases  the  rocks  are  exposed 
in  continuous  sections  from  bottom  to  top,  and  each  zone  is  open  for 
inspection  over  considerable  horizontal  space.  Nevertheless,  Dr. 
Kindle's  analysis  of  the  faunal  contents  of  the  Ithaca  formation  is 
more  complete  than  anything  else  published,  and  it  presents  statistics 
from  which  a  fair  idea  of  the  bionic  values  of  the  species  composing 
the  faunas  may  be  estimated. 

The  dominant  species  of  the  fauna  are  the  following,  the  figures 
indicating  the  frequency  of  occurrence  of  the  species  in  the  54  fau- 
nules  analyzed : 

Table    XIII. — Productella    speciosa   fauna:    Dominant  species   of    the    Ithaca 
formation  at  Ithaca,  N.  Y. 

1 .  Spirifer  pennatus  var.  posterns 3a 

2.  Productella  speciosa 25 

3.  Modiomorpha  subalata  var.  chemungensis . . 25 

4.  Chonetes  scitulus 24 

5.  Cyrtina  hamiltonensis 23 

6.  Palaeoneilo  filosa 21 

7.  Camarotcechia  eximia  and  stephani 21 

8.  Atrypa  reticularis 20 

9.  Stropheodonta  mucronata 19 

10.  Actinopteria  boydi 19 

11.  Pleurotomaria  capillaria 19 

12.  Stictopora  meeki 17 

13.  Palaeoneilo  constricta .     . 17 

14.  Cypricardella  bellistriata 15 

15.  Spirifer  mesistrialis 14 

16.  Leiorhynchus  mesicostale . .  14 

17.  Grammysia  subarcuata 14 

18.  Orthoceras  bebryx  var.  cayuga 14 

19.  Ambocoelia  umbonata.  _ 13 

This  maybe  considered  as  a  standard  list  of  the  fauna  of  the  Ithaca 
formation.  Three  points  must  be  noted,  however:  (1)  Several  char- 
acterisUc  species  of  the  Ithaca  formation  are  not  in  this  list,  because 
they  do  not  occur  as  frequently  as  all  these  other  species;  (2)  a  large 
proportion  of  this  standard  list  is  made  up  of  common  Hamilton  spe- 
cies (i.  e.,  species  of  the  standard  Tropidoleptus  carina! us  fauna); 
(3)  the  species  which  are  peculiar  and  dominant  are  closely  related 
to  species  of  the  Tropidoleptus  carinatus  fauna.  It  will  be  noticed, 
however,  that  not  a  single  one  of  the  dominant  species  of  the  Tropi- 
doleptus carinatus  fauna  appears  until  we  reach  the  thirteenth  species 
in  this  list;  and  among  these  19  dominant  species  of  the  typical 
Ithaca  formation  only  two  species  of  the  dominant  Tropidoleptus 
fauna  are  present,  i.  e.,  Palaioneilo  constricta  and  Ambocoelia  umbo- 
nata. 


Williams.]  FAUNAL    DISSECTION    OF   THE    DEVONIAN.  75 

Before  further  discussing  this  list  it  may  be  well  to  present  the  list 
of  dominant  species  of  the  eastern  region  where  the  underlying 
Hamilton  formation  contains  the  standard  Tropidoleptus  carinatus 
fauna,  above  which  the  sedimentation  was  continuous.  It  may  be 
inferred  that  the  latter  fauna  was  not  driven  out  from  this  eastern 
region,  but  lived  on  continuously,  suffering  only  genetic  evolution, 
uncomplicated  b}T  the  effects  of  shifting  its  habitation.  The  distribu- 
tional values  of  the  species  will  be  furnished  by  the  statistics  of  the 
eastern  faunules. 

Analysis  of  the  statistics  gathered  by  Professor  Prosser  in  the  east- 
ern counties  of  New  Yorka  shows  a  larger  number  of  species  in  the 
formation  than  is  reported  by  Kindle.  This  increase  is  probably 
due  to  the  wider  area  examined,  presenting,  undoubtedly,  local  dif- 
ferences in  original  environmental  conditions.  The  localities  from 
which  the  faunas  of  the  Ithaca  formation  are  reported  bj7  Prosser  are 
67  in  number,  and  are  distributed  from  Smyrna,  Chenango  County, 
through  Chenango,  Otsego,  Delaware,  and  Schoharie  counties. 

The  faunules  contain  100  species.  Of  these,  78,  or  over  three-quar- 
ters, occur  also  in  the  standard  Tropidoleptus  fauna.  All  the  12 
species  of  the  dominant  list  of  the  Tropidoleptus  fauna  occur  also  in 
the  faunules  of  the  Ithaca  formation.  These  12  species,  arranged  in 
the  order  of  their  distributional  dominance  in  the  Ithaca  formation, 
are  shown  in  Table  XIV,  the  first  column  representing  collections 
from  07  localities,  the  second,  collections  from  14  localities. 

Table  XIV. — Productella  speciosa  fauna:  Twelve  dominant  species  of  the  Tropi- 
doleptus fauna  found  also  in  the  Ithaca  formation  of  the  eastern  counties  of 
New  York. 

[The  starred  species  occur  also  in  the  Portage  formation.] 


1.  Spirifer  pennatus 

*2.  Tropidoleptus  carinatus 

3.  Nucula  bellistriata 

*4.  Palaeoneilo  constricta  .  _ 
*5.  Nuculites  oblongatus  . . 

*6.  Phacops  rana  .  - 

*7.  Nucula  corbuliformis    . 

8.  Ambocoelia  umbonata . . 

9.  Athyris  spiriferoides  _ .  - 
10.  Nuculites  triqueter 

*11.  Spirifer  granulosus 

12.  Chonetes  coronatus 


31 

13 

31 

13 

i 

4 

7 

4 

6 

5 

6. 

5 

6 

4 

o 

3 

2 

2 

2 

2 

2 

2 

2 

1 

«  Classification  and  distribution  of  the  Hamilton  and  Chemung  series  of  central  and  eastern 
New  York,  Part  1,  by  C  S.  Prosser:  Fifteenth  Ann.  Rept.  State  Geologist  New  York,  L895,  pp 
87-225. 

Idem,  Part  2:  Seventeenth  Ann.  Rept.  State  Geologist  New  York,  1W0,  pp.  67-327. 


76 


CORRELATION    OF    GEOLOGICAL    FAUNAS. 


[BULL.  210. 


The  first  2  species  of  Table  XIV  are  still  dominant  in  the  fau- 
nule  aggregate,  but  the  other  10  species  of  the  list  have  lost  their 
preeminence  and  are  replaced  by  other  species. 

This  fact  will  be  better  appreciated  by  examination  of  the  list  of 
species  having  highest  distributional  and  abundance  values  in  the 
Ithaca  faunules.  Table  XV,  representing  collections  from  67  locali- 
ties, shows  the  dominant  species  of  the  eastern  extension  of  the  Ithaca 
formation.  Comparison  of  Tables  XIV  and  XV  will  show  how  com- 
pletely the  dominant  species  of  the  Tropidoleptus  carinatus  fauna 
(excepting  the  two  chief  species)  have  lost  their  supremacy  in  the 
fauna,  the  highest  frequency  value  of  the  last  10  species  of  Table  XIV 
appearing  far  below  the  twelfth  in  rank  of  the  dominant  list: 

Table  XV. — Productella  speciosa  fauna:  Dominant  species  of  the  eastern  exten- 
sion of  the  Ithaca  formation. 


1.  Spirifer  mesistrialis 

2.  S.  pennatus 

3.  Tropidoleptus  carinatus 

4.  Camarotoechia  eximia 

5.  Chonetes  setigerus  . 

6.  Paracyc-las  lirata 

7.  Chonetes  scitulus. . . 

8.  Leiorhynchus  mesicostalr 

9.  Actinopteria  boydi 

10.  Camarotcechia  stephani  . 

11.  Pakeoneilo  emarginata 

12.  Cypricardella  gregaria 


36 

6 

31 

4 

31 

0 

19 

6 

20 

0 

18 

0 

15 

0 

12 

o 

12 

1 

9 

3 

12 

0 

9 

1 

24 

11) 
li) 
12 
9 
4 
9 
7 
7 
7 
0 
4 


In  the  first  column  of  Table  XV  is  given  the  number  of  positively 
identified  occurrences  in  (17  analyzed  faunules.  In  the  second  column 
are  the  additional  times  in  which  the  identifications  are  marked  as 
doubtful.  The  figures  in  the  third  column  indicate  Ihe  number  of 
cases  in  which  the  species  is  marked  abundant  or  common  in  the 
faunule  analyzed. 

In  the  case  of  Spirifer  mesistrialis  the  species  most  readily  confused 
with  it  is  S.  granulosus.  That  species  is  recorded  twice  positively, 
with  4  questionable  identifications. 

Spirifer  pen  mil  as  may  be  confused  with  S.  pennatus  var.  posterns, 
of  which  1  doubtful  case  is  recorded,  and  with  8.  mesicostalis,  of  which 
2  positive  and  4  doubtful  identifications  occur.  In  4  of  the  faunules 
in  which  the  latter  species  is  mentioned  it  is  common  or  abundant. 


PRODUCTELLA   SPECIOSA   FAUNA. 

Iii  the  67  faunules  examined  in  this  eastern  region  Productella 
speciosa  occurs  but  once  positively,  and  four  times  it  is  reported  with 


WILLIAMS.] 


FAUNAL    DISSECTION    OF    THE    DEVONIAN. 


77 


doubtful  specific  identification,  and  only  one  other  case  of  a  Produc- 
tella  is  reported.  This  suggests,  in  connection  with  its  standing 
second  in  dominance  in  the  list  for  the  Ithaca  formation  at  Ithaca, 
that  the  immigration  of  the  fauna  was  from  the  west,  and  that  it  had 
not  so  strongly  occupied  the  eastern  area  as  that  of  central  New  York 
at  this  horizon. 

Analysis  of  this  list  shows  that  two  of  the  dominant  species  of  the 
Tropidoleptus  fauna  are  still  dominant,  but  the  other  species  of  the 
list  have  dropped  out.  Among  the  species  of  the  list  which  occur  in 
the  Tropidoleptus  fauna,  but  are  there  rare,  are  Actinopteria  boydi 
and  Paracyclas  Virata.  These,  though  frequent  in  the  faunules  occur- 
ring east  of  Fulton,  Schoharie  County,  are  rare  in  the  Hamilton  for- 
mation west  of  that  point.  Cy'pricar  delta  gregaria,  though  occa- 
sional, is  very  rare  in  the  eastern  Hamilton  faunules.  Another 
species  of  the  genus,  C.  bellistriata,  is  common  in  the  Hamilton  for- 
mation. 

It  is  evident,  therefore,  upon  purely  paleontological  grounds,  that 
this  fauna,  classified  as  of  the  Ithaca  formation,  is  distinct  from  and 
later  than  the  Tropidoleptus  fauna  of  the  Hamilton  formation,  and 
this  is  evident  in  spite  of  the  fact  that  it  contains  all  of  the  12  domi- 
nant species  of  the  latter  fauna.  The  discrimination  between  the  two 
is  based  upon  a  change  in  the  bionic  values  of  the  dominant  species 
and  upon  the  introduction  of  new  species  or  varieties  which  are  either 
rare  or  wanting  in  the  typical  Tropidoleptus  fauna. 

The  correctness  of  this  interpretation  is  further  supported  by  the 
presence  of  species  entirely  wanting  in  the  underlying  Hamilton  for- 
mation of  the  region,  but  present  in  the  Ithaca  formation  at  its  typ- 
ical expression  in  Tompkins  County. 

Table  XVI  is  compiled  from  the  statist  ics  reported  by  Prosser  in 
the  papers  already  referred  to: 


Table  XVI. — Productella  speciosa  fauna:  Twenty-one  species  characteristic  of 
the  Ithaca  formation  of  eastern  Neiv  York  and  Pennsylvania  not  occurring  in 
the  Tropidoleptus  fauna. 

[The  starred  species  are  dominant  at  Ithaca.  | 


*  1.  Camaroteechia  stephani. 

*  2.  C.  eximia. 

3.  Cryptonella  eudora. 

*  4.  Leiorhyiichus  mesicostale. 

5.  Orbiculoidea  media. 

6.  O.  neglecta. 

*  7.  Productella  speciosa. 

*  8.  Spirifer  mesistrialis.  - 

*  9.  S.  pennatus  var.  posterns. 

10.  Actinopteria  perstrialis. 

11.  A.  theta. 


12.  Grammy sia  elliptica. 

13.  G.  globosa. 

14.  G.  nodocostata. 

15.  Leda  brevirostris. 
Lrmulicardinm  ornal  us. 
Modiomorpha  subalata  var. 

mungensis. 
Prothyris  lanceolata. 
Pterinopecten  sul  ><  >rl  >icularis. 

20.  Schizodus  ellipticus. 

21.  Coleoms  acicumm. 


16 
*17 

18 
19 


che- 


Of  these  21  species  not  in  the   Tropidoleptus  fauna  0  appear  also 


in  the  Portage  list. 


78  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

All  the  12  most  dominant  species  of  the  Tropidoleptus  fauna  are 
present,  as  has  already  been  mentioned,  and  besides  more  than 
three-quarters  (tV8tt)  °f  the  total  listed  species  are  of  the  Tropido- 
leptus fauna.  Seven  of  the  21  species  not  in  the  Hamilton  below 
are  among  the  dominant  species  of  the  fauna  of  the  typical  Ithaca 
formation  at  Ithaca.  They  are  starred  in  Table  XVI.  Three  other 
species,  together  with  the  7  just  mentioned,  occur  in  the  typical 
Ithaca  and  in  the  formation  identified  as  Ithaca  in  the  eastern  coun- 
ties.    These  three  species  are: 

Cryptonella  endora. 
Grammysia  elliptica. 

Actinopteria  perstrialis. 

IMMIGRANT   SPECIES   OF   ITHACA   FORMATION. 

Among  the  species  appearing  for  the  first  time  in  the  strata  of  this 
region,  distinct  affinities  with  the  Iowan  and  related  faunas  are  evi- 
dent.    Examples  are: 

Productella  hallana, 

Pugnax  pugmis,  and 

Spirifer  (Reticnlaria)  Levis. 

The  common  Productella  speciosa  may  belong  to  the  same  group, 
though  it  is  possible  that  this  is  a  case  of  direct  evolution  from  Pro- 
din  -fella  spimdicosta  o  f  the  I  lam  i  1  ton  formation .  Eh  ynchonella  venus- 
tula  (= Hypothyris  cuboides)  of  the  Tully  limestone  is  a  still  earlier 
immigrant,  as  was  shown  in  a  paper  on  the  Cuboides  zone/' 

Orthis  (Schizophoria)  tuUiensis  is  another  closely  related  to  Orthis 
impressa  of  the  Ithaca  zone,  and  believed  to  be  a  variet}^  of  Schizo- 
phoria si  rial  ul  a  (Schlotheim).  The  Goniatites  are  associated  with  the 
western  typical  Portage  fauna,  rather  than  with  the  Hamilton  fauna, 
which  was  restricted  farther  east  at  the  time  of  deposition  of  the  Ithaca 
beds.  This  may  indicate  immigration,  but  the  case  is  not  clear  from 
the  evidence  now  before  us.  The  Cardiolas  of  the  Portage  group  at 
Ithaca  and  farther  west  in  the  Genesee  Valley  are  immigrants,  and 
represent  the  wider  fauna  of  Europe,  but,  so  far  as  known,  the  pres- 
ent faunas  of  Iowa  do  not  contain  this  genus  (i.  e.,  Glyptocardia). 

The  High  Point  fauna  (as  given  in  full  by  Dr.  J.  M.  Clarke)  b  con- 
tains still  further  traces  of  the  western  Iowa  Devonian  fauna. 

The  lower  appearance  of  this  fauna  is  indicated  about  Ithaca  in  the 
Ithaca  formation,  in  which  no  trace  of  Spirifer  disjunctus  has  been 
discovered;  but  in  the  High  Point  station  at  Naples  that  characteristic 
Chemung  species  is  reported  by  Dr.  Clarke,  although  I  had  not  seen 
it  when  writing  up  the  list  reported  in  1883. 

The  faunule  of  the  High  Point  station  exhibits  its  characteristics,  but 

a  The  Cuboides  zone  and  its  fauna:  a  discussion  of  methods  of  correlation:  Bull.  Geol.  Soc.  Am., 
Vol.  I,  1890,  pp.  481-501. 

&On  the  higher  Devonian  faunas  of  Ontario  County,  N.  Y.,  by  J.  M.  Clarke  (chapter  on  fauna 
of  Chemung  beds  at  High  Point,  pp.  72,  etc.):  Bull.  U.  S.  Geol.  Survey  No.  16,  1885;  see  also 
Am.  Jour.  Sci.,  3d  series,  Vol.  XXV,  Feb.,  1883. 


williams.T  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  79 

as  traces  of  the  species  occur  at  several  points  in  the  strata  earlier  and 
farther  eastward,  it  is  evident  that  the  eastern  migration  began  as 
early  as  the  Tully  limestone  depression,  which,  for  the  region  in  which 
it  is  represented  by  a  limestone,  terminated  the  pure  Tropidoleptus 
fauna. 

The  full  list  of  High  Point  is  given  in  Dr.  Clarke's  paper  (sec  fore- 
going footnote),  and  the  following  species  there  listed  are  also 
reported  from  the  Iowa  Devonian. 

Table  XVIL— The  Pugnax  pugnus  fauna  of  High  Point,  New  York. 

Camarotoechia  contracta  var.  saxatilis.      Sclrizophoria  iowensis. 

Pugnax  pugnus.  Dalmanella  infera. 

Atrypa  reticularis.  Orthothetes  chemungensis. 

A.  hystrix.  Strophonella  reversa. 

Spirifer  orestes.  Stropheodonta  calvini. 

S.  hungerfordi.  S.  variabilis. 

S.  bimesialis.  S.  canace. 

S.  subattenuatus.  S.  arcuata. 

Productella  (dissimilis)  hallana.  Fistulipora  occidens; 

These  facts  leave  no  doubt  as  to  an  intimate  affinity  existing 
between  the  High  Point  and  associated  faunas  of  New  York  and  the 
Iowa  Devonian  fauna,  as  was  claimed  when  I  first  called  attention 
to  the  High  Point  fauna  in  1883/' 

These  species,  common  to  the  Iowa  and  Now  York  faunule,  may  be 
regarded  as  characteristic  species  of  this  Pugnax  pugnus  fauna.  The 
fauna  is  mingled  with  the  Tropidoleptus  carinatus  fauna  to  form 
the  aggregate  of  the  Ithaca  formation.  1  in  1  at  Ithaca  it  is  not  so 
strongly  represented  as  at  the  High  Point  locality  at  the  south  end  of 
Canandaigua  Lake,  in  Ontario  County. 

The  study  of  the  relations  of  the  Cuboides  fauna  to  a  world-wide 
distribution  led  to  the  conception  that  affinities  expressed  by  faunas 
may  be  due  to  migration  rather  than  to  direct  evolution  of  the  preva- 
lent fauna  living  in  the  region.  This  idea  was  set  forth  in  the  paper 
on  the  Calx  tides  fauna. h 

The  observation  that  the  Devonian  faunas  of  Iowa  are  more 
closely  akin  to  those  of  the  Mackenzie  River  Valley  and  of  Europe,  and 
the  fact  that  the  faunas  reported  from  South  America  are  more  closely 
akin  to  the  faunas  of  the  New  York  Hamilton  than  to  the  Euro- 
pean Devonian  faunas,  furnished  the  third  clue  to  the  interpreta- 
tion of  fauna!  history,  viz,  long  periods  of  uniformity  in  the  general 
geographical  condition  of  the  earth's  surface  have  determined  the 
local  characteristics  of  the  marine  faunas,  and  a  change  in  the  fauna 
of  a  local  province  may  indicate  important  geological  change's  involv- 

«  On  a  remarkable  fauna  at  the  base  of  the  Chemung  group  in  New  York:  A.m.  Jour.  Sci.,  :i<l 
series,  Vol.  XXV,  1883,  i>.  97. 

''The  Cuboides  zone  and  its  fauna;  a  discussion  of  methods  of  corn -hit  ion:  liull.  Geol.Soc.Am., 
Vol.  I,  1890,  pp.  4S1-5IK). 


80  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

ing  the  geography  of  wide  areas  of  surface.  This  was  indicated  in 
the  paper  written  in  1892." 

The  list  made  by  Dr.  Kindle  from  the  typical  Ithaca  formation 
contains  84  species,  specifically  identified.  Of  these,  47  are  not 
recorded  for  the  eastern  Hamilton  stations  reported  by  Prosser,  and 
2  only  of  these  47  species  are  in  the  Cleland  list  of  Cayuga  Lake 
Hamilton,  or  in  the  Eighteenmile  Creek  Hamilton  faunal  list  given  by 
Grabau.  Thus  there  are  45  species,  or  more  than  half  of  the  species 
listed,  which  are  specifically  distinct  from  the  species  of  the 
Tropidoleptus  fauna. 

The  other  half  of  the  Ithaca  faunal  list  is  composed  of  species 
belonging  to  the  Tropidoleptus  carinatus  fauna  of  the  Hamilton  for- 
mation of  the  general  region.  About  half  of  the  peculiar  species  is 
represented  by  closely  related  species  in  the  Tropidoleptus  fauna, 
and  therefore  it  may  be  assumed  that  three-quarters  of  the  fauna  of 
the  Ithaca  formation  is  derived  by  evolution  directly  from  the  Tropi- 
doleptus fauna.  The  other  quarter  may  be  derived  by  migration 
from  a  more  distanl  source. 

In  both  cases  of  origin,  however,  it  will  be  noted  that  varietal  modi- 
fications have  taken  place.  Enough  mutation  occurred  to  furnish 
a  list  of  over  40  species  to  characterize  the  Ithaca  formation,  as  it 
occurs  in  the  column  of  central  New  York. 

Of  the  species  peculiar  to  the  fauna  of  the  Ithaca  formation,  only  13 
are  reported  in  the  eastern  counties  at  any  horizon,  from  the  Hamil- 
ton  proper  up  to  the  departure  of  the  marine  species  with  the  sedi- 
ments of  the  red  Catskill  shales  and  sandstones. 

It  will  be  noted  also,  b}T  examination  of  the  lists  already  given  that 
5  out  of  the  1<>  most  dominant  species  of  the  Ithaca  list  are  Hamilton 
species — i.  e.,  they  belong  to  the  Tropidoleptus  fauna,  and  10  of  the 
most  abundant  18  species  are  Hamilton,  all  of  which  are  recorded 
from  13  to  24  times  among  the  54  lots  analyzed. 

It  is  evident  from  this  last  observation  that  the  old  fauna  which 
had  spread  over  the  Ithaca  region  during  the  sedimentation  of  the 
Ithaca  formation  has  a  preponderance  of  species  belonging  to  the 
Tropidoleptus  fauna,  both  in  the  number  of  species  and  in  domi- 
nance of  the  species  in  the  fauna.  If  it  were  far  enough  removed  from 
the  Hamilton  formation  to  make  correlation  by  stratigraphical  evi- 
dence impossible,  the  faunal  characteristics  would  lead  to  its  associa- 
tion with  the  Hamilton,  as  a  stratigraphically  equivalent  formation 
whose  fauna  was  modified  by  change  of  conditions  of  environment, 
whereas  the  facts  now  before  us  leave  no  doubt  as  to  its  actual  suc- 
cession above  the  other  formation. 

The  comparison  of  the  Ithaca  fauna  with  the  fauna  belonging  to 
the  eastern  extension  of  the  same  formation  shows  that  the  Tropido- 


«The  scope  of  paleontology  and  its  value  to  geologists:  Proc.  Am.  Assoc.  Adv.  Set,  Vol.  XLI, 
pp.  149-170. 


williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  81 

leptus  fauna  is  dominant  to  a  greater  degree  in  the  eastern  counties 
than  at  Ithaca,  not  only  for  the  particular  part  of  the  column  in 
which  the  Ithaca  fauna  is  abundant,  hut  all  the  way  upward  so  long- 
as  a  marine  fauna  is  present  in  the  rocks  of  the  region.  On  the  other 
hand,  very  few  species  characteristic  of  the  Ithaca  formation  (though 
enough  to  mark  the  horizon),  reach  into  the  extreme  eastern  part  of 
the  New  York  area.  Following  the  strata  farther  westward  it  is 
found  that  in  the  Genesee  River  Valley  the  fauna  so  abundant  in  the 
Ithaca  formation  is  entirely  wanting,  and  is  there  replaced  by  the 
sparse  Cardiola  fauna  of  the  Portage  formation  of  that  region. 

MUTATION   AND   CORRELATION   OF  THE  FAUNAS. 

This  critical  examination  of  the  typical  fauna  of  the  Ithaca  forma- 
tion at  Ithaca  and  its  representatives  at  corresponding  horizons  east 
of  Ithaca  demonstrates  some  important  facts  regarding  the  mutation 
and  correlation  of  fossil  faunas. 

(1)  The  Tropidoleptus  fauna,  belonging,  typically,  to  the  Hamilton 
formation,  and  in  western  New  York  known  to  cease  entirely  with  the 
Genesee  shale  or  at  a  corresponding  horizon,  appears  in  eastern  New 
York  with  its  dominant  species  still  prominent  at  a  horizon  much 
higher  stratigraphically. 

(2)  Above  the  Genesee  shale,  in  the  meridian  of  Cayuga  Lake,  a 
fauna  (the  Productella  speciosa  fauna)  appears  with  many  of  the 
dominant  species  of  the  Tropidoleptus  fauna,  but  with  other  species 
characteristic  of  the  Ithaca  formation. 

(3)  Eastward  from  Cayuga  Lake,  at  the  stratigraphical  place  in  the 
sections  corresponding  to  the  Ithaca  formation,  the  characteristic 
species  of  the  Productella  speciosa  fauna  become  more  infrequent, 
while  at  the  same  time  the  Tropidoleptus  fauna  increases  in  domi- 
nance. 

(4)  Westward  from  Ithaca  the  Productella  speciosa  fauna  is  trace- 
able a  few  miles  only,  and  disappears  before  reaching  the  Genesee 
Valley,  where  it  is  replaced  by  the  Cardiola  fauna  of  the  Portage. 

This  series  of  facts  demonstrates  another  general  law  of  the  history 
of  organisms,  as  expressed  by  the  range  of  species,  viz: 

(5)  The  stratigraphical  horizon  of  the  incursion  of  new  species  into 
a  region  may  be  sharply  recognized  long  before  the  common  fauna  of 
the  region  is  dispersed  or  dies  out. 

((5)  The  characteristic  species  of  the  Productella  speciosa  fauna  of 
the  Ithaca  formation  as  it  occurs  at  Ithaca  arc  present  and  dominanl 
in  these  eastern  counties  of  the  State,  although  the  Tropidoleptus  fauna 
still  constitutes  75  per  cent  of  the  fauna  and  is  represented  by  all  its 
most  characteristic  species. 

(7)  If  the  composition  of  the  faunules  still  higher  up  in  the  eastern 
counties  be  examined,  it  will  be  found  that  this  same  Tropidoleptus 

Bull.  210—03 6 


82  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

fauna  dominates  in  the  rocks  above  the  Oneonta  sandstone  and  on 
upward  until  it  is  finally  extinguished  by  the  deposit  of  red  Catskill 
sediments. 

(8)  Nevertheless,  on  tracing  the  strata  westward,  the  ProducteUa 
speciosa  fauna  is  still  dominant  as  the  Cayuga  Lake  meridian  is 
reached,  with  very  little  trace,  in  the  higher  zones,  of  the  Tropidoleptus 
fauna;  but  that  the  latter  fauna  is  still  living  late  in  the  sequence  is 
shown  by  a  recurrent  faunule  in  the  midst  of  the  disjunctus  fauna  of 
Owego,  with  its  Phacops  rana,  Tropidoleptus  carina/ us,  and  Cypricar- 
dell  a  bell  istr lata. 

(!>)  Following  the  strata  Avestward  to  the  Genesee  River  sect  ion,  it 
is  found  that  the  Card  tola  fauna  of  the  Portage  formation  has  entirely 
replaced  the  ProducteUa  speciosa  fauna  of  Ithaca  and  its  eastern 
equivalents. 

If  now  we  were  to  interpret  this  into  the  dual  nomenclature,  we 
would  say  that  the  Portage  formation  of  the  Genesee  Valley,  with  its 
Cardiola  fauna,  is  equivalent,  in  the  Ithaca  region,  to  the  Portage 
formation  with  its  Spirifer  Icevis  fauna  together  with  the  Ithaca  for- 
mation with  its  ProducteUa  speciosa  fauna,  and  that  these  latter  two 
are  equivalent ,  st rat  igraphieally,  to  the  so-called  Ithaca  and  Oneonta 
formations  of  Chenango  and  Otsego  counties,  and  to  the  upper  part 
of  what  has  been  called  the  "Hamilton  formation"  in  the  extreme 
eastern  counties  of  New  York,  holding  the  Spirifer  mesistrialis  fauna 
of  that  region  which  there  extends  upward  to  the  base  of  the  Catskill 
formation. 

CHEMUNG  FORMATION   AND   ITS  FAUNA. 

The  case  of  the  Tthaca  formation  and  its  fauna,  composed  of  a 
majority  of  species  of  the  Tropidoleptus  carinatus  fauna  and  but  a 
few  relatively  characteristic  species,  leads  to  the  inquiry:  What  is  the 
Chemung  fauna,  and  is  it  to  be  recognized  in  the  eastern  half  of  New 
York  State  prior  to  the  sedimentation  of  the  Catskill  formation?  These 
questions  are  not  to  be  answered  by  examination  only  of  those  species 
of  the  fauna  which  are  exhibited  in  the  sections  within  the  eastern 
region.  We  must  first  ascertain  the  content  of  the  fauna  where  it  is 
typically  and  fully  represented  in  the  western  part  of  the  State. 

In  the  western  half  of  New  York  and  across  the  State  line  in  Penn- 
sylvania the  Chemung  formation  is  sharply  differentiated,  strati- 
graphieally,  from  the  Hamilton  formation.  Between  the  two  are 
found  several  hundred  feet  of  sediments  containing  no  trace  of 
either  the  preceding  or  the  following  faunas.  These  sediments  are 
divisible  into  two  easily  distinguished  parts — the  black  Genesee  shale 
and  the  Portage  group.  The  lower  part  of  the  latter  is  typically  a 
greenish  argillaceous  shale;  its  upper  part  is  a  flaggy  sandstone  with 
some  massive  sandstone  beds  at  the  top. 

The  beds  following  the  Portage  sandstone  contain  a  characteristic 
set  of  marine  fossils  which  may  be  taken  as  the  type  of  the  Spirifer 


Williams.]  FAUNAX    DISSECTION    OF    THE    DEVONIAN.  83 

disjunctus  fauna,  and  the  formation  through  which  this  fauna  prevails 
is  the  Chemung  formation. 

SPIRIFER   DISJUNCTUS   FAUNA. 

The  fauna  of  this  typical  Chemung  formation,  as  it  appears  in  the 
southern  tier  of  counties  in  the  western  half  of  New  York  State,  may 
be  appropriately  called  the  Spirifer  disjunctus  fauna  from  the  brach- 
iopod  species  of  that  name  which  is  abundantly  represented  in  the 
rocks  of  the  formation  and  is  widely  distributed  elsewhere. 

In  1884,  in  Bulletin  No.  3,  the  fauna  was  critically  separated  from 
the  fauna  occuring  below  it,  south  of  Ithaca,  and  the  name  disjunc- 
tus fauna  was  applied  to  it.  The  original  list  of  species  of  the  f : tu- 
nnies examined  in  the  counties  directly  south  of  Cayuga  Lake  (as  then 
identified)  included  46  species. 

In  a  preliminary  "Catalogue  of  the  fossils  of  the  Chemung  period 
of  North  America,""  published  two  years  before,  in  November,  1882, 
a  list  was  given  containing  94  genera  with  268  species  and  varieties. 
Since  then  the  New  York  State  paleontologist  has  published  revisions 
of  the  Lamellibranchiata,  the  Brachiopoda,  and  the  Crustacea  of  the 
Devonian  formations  of  the  State,  and  it  is  quite  probable  that  now 
the  number  of  genera  may  have  increased  to  150  and  the  species 
to  400,  or  perhaps  500;  but  the  literature  in  which  the  species  are 
described  gives  very  little  evidence  upon  which  to  base  a  definite 
estimate  of  the  bionic  values  of  these  species — either  the  bionic 
value  as  expressed  in  terms  of  frequency  of  individuals  in  the  local 
composition  of  the  faunas,  or  that  expressed  in  terms  of  frequency 
of  appearance  in  geographical  distribution.^ 

The  first  attempt  to  form  a  list  of  the  dominant  species  of  the  dis- 
junctus fauna,  purely  on  the  basis  of  what  I  have,  in  the  presenl 
paper,  denominated  bionic  values  of  the  species,  was  made  in  1884, 
in  a  paper  on  the  Ithaca  faunas. c 

The  following  list  was  prepared  on  that  basis,  as  roughly  estimated 
in  the  field,  without,  however,  recording  the  exact  statistics  of  abun- 
dance and  frequency,  statistics  which  have  been  insisted  on  in  later 
investigations. 

Table  XVIII.— Spirifer  disjunctus  fauna:    Dominant  species  of  the  Chemung 
,  formation  south  of  Ithaca,  N.  Y.  {roughly  estimated  in  the  field) . 


1.  Schizophoria  tioga. 

2.  S.  carinata. 

3.  Stropheodonta  mucronata. 

4.  Productella  lachrymosa. 

5.  Spirifer  disjunctus. 

6.  Atrypa  spinosa  hystrix. 


7.  Spirifer  mesistrialis. 

8.  Ambocoelia  gregaria. 

9.  Spirifer  (Delthyris)  mesicostalis. 

10.  Orthothetes  clienmngensis. 

11.  Pteiinea  chemungensis. 

12.  Camarotoechia  contracta. 


The  twelfth  species  is  not  mentioned   in   my  List    from   station  72, 
near  Park  station  of  the  Utica,  Ithaca  and  Elmira  Railroad  (p.  22), 


"University  Press,  Cornell  University,  Ithaca,  N.  Y. 
&See  the  discussion  of  bionic  values  of  fossils,  p.  124. 
o  Bull.  U.  S.  Geol.  Survey  No.  3,  1884,  pp.  22-23. 


84  •  OOEEELATION    OF   OEOLOGICAL    FAUNAS.  [bull.  210. 

but  it  is  reported  in  the  typical  Chemung  fauna  on  the  following  page, 
as  found  at  Chemung  Narrows,  and  is  conspicuous  in  the  more  char- 
acteristic Chemung  faunules  of  the  western  part  of  the  State. 

Another  basis  for  estimating  the  dominant  characteristics  of  the 
fauna  of  the  Chemung  formation  is  found  in  the  statistics  published 
in  Bulletin  41,  U.  S.  Geological  Survey." 

In  this  bulletin  lists  of  the  species  were  tabulated  primarily  to 
indicate  the  composition  of  the  local  and  temporary  faunules.  Thirty- 
seven  such  Chemung  faunules  are  analyzed.  The  value  of  clearly 
distinguishing  the  geographical  from  the  geological  modification 
of  the  faunules  was  not  full}'  appreciated  when  the  bulletin  was 
written.  As  the  investigations  have  progressed,  however,  it  has 
become  clear  that  modification  of  a  general  fauna,  coincident  with  a 
few  miles  of  separation  in  space,  geographically,  may  be  as  great  as, 
or  even  greater  than,  the  modification  coincident  with  passage  upward 
stratigraphically  through  tens  or  even  hundreds  of  feet  of  sediments. 
These  two  kinds  of  bionic  value  (geographical  and  geological)  are  not 
so  sharpl}T  distinguished  in  Bulletin  41  as  they  might  be,  but  the  statis- 
tics there  given  will  serve  for  estimating  the  general  bionic  values  of 
the  constituent  species  of  the  fauna.  These  values  are  not  generally 
evident  in  the  descriptive  reports  of  the  individual  species  concerned, 
and  particular  attention  to  collecting  the  evidence  must  be  given, 
both  in  the  field  and  when  the  collections  of  fossils  are  analysed  in 
the  laboratory,  in  order  to  exhibit  the  bionic  values  of  the  species  of 
the  fauna. 

Difficulties  in  the  way  of  preparing  an  exact  list  of  the  dominant 
species  of  the  Spirifer  disjunctus  fauna  arise  from  still  another  source. 
Many  of  the  species  of  this  fauna  are  in  a  variable  condition,  and  the 
separate  faunules  present  strong  contrasts  in  the  particular  aggrega- 
tion of  species  making  up  the  faunules,  which  call  for  still  fuller 
investigation.  This  elasticity  of  the  fauna  is  what  might  be  expected 
on  the  theory  of  its  origin  in  the  New  York  province  by  immigration. 
The  various  elements  of  the  fauna  were  occupying  new  territory  (or 
aquilory,  we  might  more  properly  say),  and  were  struggling  into  a 
new  adjustment  of  equilibrium  among  themselves  and  in  their  new 
environment.  The  more  vigorous  the  species  were  the  more  plastic 
we  may  suppose  them  to  have  been.  However  the  facts  may  be 
theoretically  explained,  it  is  noticeable  that  many  of  the  species 
of  both  the  Ithaca  and  Chemung  formations  are  in  a  remarkably 
variable  condition. 

The  spirifers,  the  productellas,  the  orthids,  the  rhynchonellas,  the 
pterineas,  and  aviculoids  in  general,  which  constitute  the  larger  part 
of  any  good  sample  of  the  Spirifer  disjunctus  fauna,  are  so  vari- 
able that  two  authors  will  almost  certainly  disagree  in  naming  the 
species  of  any  particular  lot  of  fossils,  and  even  the  ablest  paleon- 
tologist will  differ  in  his  own  distribution  of  the  specimens  among  the 


( On  the  fossil  faunas  of  the  Upper  Devonian— the  Genesee  section,  New  York. 


WILLIAMS.  I 


FAUNAL    DISSECTION    OF    THF    DEVONIAN. 


85 


species  at  different  times,  according  to  the  order  in  which  he  happens 
to  take  them  up  for  study.  In  Schuchert's  list «  there  are  15  species 
of  Prodicctella  recognized  as  belonging  to  the  Chemung  fauna.  Spiri- 
fersof  the  three  types — disjunctus,  mesicostalis,  and  mesislridlis — are 
present  and  each  type  is  widely  variable.  The  rhynchonellas  of  the 
contractu,  sappho,  and  eximia  types  are  all  very  variable,  the  last 
appearing  more  conspicuously  below  and  the  others  higher;  but 
between  the  several  species  named  frequent  intermediate  forms  are 
found  which  it  is  difficult  to  determine  specifically.  Chonetes  scitulus 
and  Chonetes  setigera  are  extremely  difficult  to  discriminate.  A  foot- 
note to  Plate  VI,  A,  of  Hall  and  Clarke's  revision  of  the  Brachiopoda, 
contains  the  following  statement  about  the  orthids: 

The  species  of  Orthis=Schizophoria,  described  as  O.  propinqua,  O.  tulliensis, 
O.  impressa,  O.  ioivensis.  and  O.  macfarlanii,  present  so  many  features  in  com- 
mon that  further  study  and  comparison  should  be  given  them  to  determine  the 
actual  value  of  the  characters  on  which  the  specific  distinction  has  been  based, 
and  whether  these  differences  coincide  with  their  geological  relations. 

These  remarks  will  suggest  an  explanation  for  some  of  the  differ- 
ences observed  in  the  lists  of  Chemung  fossils  reported  by  different 
authors.  Nevertheless,  it  seems  reasonable  to  rely  on  the  value  of 
frequency  of  appearance  in  recorded  lists  (made  by  the  same  author) 
of  the  species  of  separate  faunules  as  evidence  of  a  corresponding 
frequency  of  the  species  in  the  actual  faunules. 

In  the  following  table  the  statistics  reported  for  the  Genesee  Valley 
faunules  are  given.  In  this  case  the  failure  to  mention  the  less  com- 
mon species  in  every  faunule  list  arose  from  the  fact  that  the  chief 
purpose  of  the  report  as  made  was  to  distinguish  the  successive  zones 
into  which  the  fauna  was  divisible.  The  lists  are  sufficient,  however, 
to  indicate  the  dominant  species. 


Table  XIX. — Spirifer  disjunctus  fauna:  Dominant  species  of  the  fauna  as 
occurs  in  the  Oenesee  Valley  section. 


Species. 

Thirty- 
seven 
locali- 
ties. 

Species. 

Thirty- 
seven 
locali- 
ties. 

1.  Spirifer  disjunctus 

24 

16 
12 

10 
9 

7 

7.  Productella  lachrymosa  and 
vars 

21 

var 

3.  Athyris  angelica 

4.  Orthothetes  chemungensis 

5.  Delthyris  mesicostalis 

6.  Schizophoria  striatula  impressa 

8.  Amboccelia  umbonata : 

9.  Sphenotus  contractus 

10.  Chonetes  scitulus 

7 
7 
7 

11.  Mytilarca  chemungensis 

1 2 .  Grammy sia  c<  >mmunis 

C 
4 

A  list  of  the   species  of  the  Chemung  formation   of  Chautauqua 
County  (prepared  by  G.  D.  Harris  in  18X7),  indicating  the  dominant 


«A  synopsis  of  American  fossil  Brachiopoda,  including  bibliography  and  synonymy:   Bull. 
U.  S.  Geol.  Survey  No.  87,  1897,  pp.  1-464. 


86  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

species  in  each  fanmile,  shows  the  following  species  to  be  dominant 
in  approximately  the  order  in  which  they  are  listed  below: 
Table  XX. — Spirifer  disjunctus  fauna:  Dominant  species  of  the  Chautauqua 

County  faunules. 


1.  Camarotoechia  contracta. 

2.  Spirifer  disjunctus. 

3.  Amboccelia  gregaria. 

4.  Camarotoechia  duplicata. 

5.  Dalmanella  leonensis. 

6.  Chonetes  scitulus. 


7.  Productella  hystricula. 

8.  Athyris  angelica. 

9.  A.  polita. 

10.  Productella  lachrymosa. 

11.  Palaeoneilo  constricta. 

12.  Orthothetes  chemungensis. 


Examination  of  these  lists  in  respect  to  the  less  common  but  char- 
acteristic species  brings  out  some  peculiarities  in  geographical  distri- 
bution which  should  be  here  indicated.  Orthids  of  the  Sehizophoria 
type,  like  impressa  and  tioga,  are  more  conspicuous  in  the  eastern 
than  in  the  western  faunules  of  the  State,  and  in  range  they  are  con-" 
spicuous  in  the  lower  rather  than  in  the  higher  portions  of  the  sec- 
tions. Spirifer  mesistrialis  is  less  conspicuous  in  the  western  than 
in  the  middle  and  eastern  part  of  the  State,  where  it  appears  as  low 
as  the  Ithaca  formation.  Delthyris  mesicostalis  of  the  characteristic 
form  is  conspicuous  in  the  Genesee  Valley  faunules  of  the  Chemung, 
but  is  infrequent  in  the  Chautauqua  County  sections.  Camarotoechia 
contracta  and  C.  duplicata  and  Athyris  angelica  and  A.  polita  are  of 
frequent  occurrence  in  the  purer  Chemung  faunas  of  the  western  part 
of  the  State  and  become  less  conspicuous  in  the  eastern  faunules. 

When  the  attempt  is  made  to  construct  a  standard  list  of  dominant 
species  of  the  Spirifer  disjunctus  fauna,  after  the  first  half  dozen  com- 
mon species,  there  is  a  much  larger  number  of  species  which  are  domi- 
nant in  some  part  of  the  region,  or  in  some  part  of  the  formation, 
though  not  characteristic  of  all  the  formation  or  of  the  whole  area  of 
western  New  York  alone. 

From  the  statistics  now  in  hand  we  may  form  the  following  stand- 
ard list  of  dominant  species  of  the  fauna,  which,  may  be  divided  into 
three  parts:  (1)  The  first  six  species  are  dominant  throughout  western 
New  York  localities,  and,  stratigraphically,  throughout  the  successive 
zones  of  the  formation;  (2)  the  species  numbered  7  to  11  are  more 
dominant  in  the  eastern  localities  in  middle  New  York;  while  (3)  the 
remaining  species  numbered  12-20  are  more  common  in  the  western 
counties  of  the  State. 

Table  XXL— Spirifer  disjunctus  fauna:  Standard  list  of  dominant  species  of 
the  Spirifer  disjunctus  fauna  for  the  New  York  province. 

1.  Spirifer  disjunctus.  11.  Atrypa  spinosa  hystrix. 

2.  Camarotoechia  contracta.  12.  Orthis  (Sehizophoria)  impressa. 

3.  Amboccelia  umbonata.  13.  Athyris  angelica  and  polita. 

4.  Orthothetes  chemungensis.  14.  Sphenotus  contractus. 

5.  Productella  lachrymosa  and  vars.         15.  Mytilarca  chemungensis. 

6.  Delthyris  mesicostalis.  16.  Grammysia  communis. 

7.  Spirifer  mesistrialis.  17.  Chonetes  scitulus. 

8.  Orthis  (Sehizophoria)  tioga.  18.  Camarotoechia  duplicata. 

9.  O.  (S.)  carinata.  19.  Dalmanella  leonensis. 
10.  Pterinea  chemungensis.                           20.  Palaeoneilo  constricta. 


WILLIAMS.] 


FAUNAL    DISSECTION    OF    THE    DEVONIAN. 


87 


Another  method  of  determining  the  constitution  of  the  Spirifer 
disjunctus  fauna  from  statistics  already  gathered  is  that  of  analyzing 
a  set  of  faunal  lists,  all  of  which  contain  Spirifer  disjunctus.  In  this 
way  the  strict  associates  of  that  species  will  be  given. 

As  a  convenient  set  of  statistics  (for  this  purpose)  the  fauna  as 
reported  in  Bulletin  41,  for  the  Genesee  section  in  western  New 
York  may  be  taken. 

Of  these  faunules  there  are  16  containing  Spirifer  disjuncUis.  In 
the  following  table  are  listed  the  more  frequent  associates  of  that 
species.  The  number  in  the  right-hand  column  indicates  the  number 
of  times  eacli  species  is  reported  in  the  10  faunules. 

Table  XXII. — The  Spirifer  disjunctus  fauna,  with  its  more  dominant  associate*, 
as  represented  in  the  Genesee  section. 


1.  Spirifer  disjunctus 

2.  Camarotcechia  contracta  . 

3.  Orthothetes  chemnngensis 

4.  Athyris  angelica  .  .  . 

5.  Chonetes  scitulus    - 

6.  Productella  hirsuta 


7.  Mytilarca  chemnngensis 6 

8.  Sphenotns  contractus 5 

9.  Orthis  (Dalmanella)  leonensis_-  4 

10.  Orthis  (Schizophoria)  impressa^  4 

1 1 .  Ambocoelia  nmbonata 4 

12.  Prodnctella  costatnla 4 


The  first  7  species  of  this  list  are  among  the  standard  forms  deter- 
mined by  the  first  method  and  listed  in  Table  XXI,  and  all  of  them 
except  the  eighth  are  actually  in  that  group  of  20  species,  but  several 
species  obtained  by  the  other  method  are  not  mentioned  in  this  list 
simply  because,  though  common  species,  they  did  not  appear  conspic- 
uously in  faunules  actually  containing  Spirifer  disjunctus,  though 
present  in  the  same  general  fauna  to  which  that  species  belongs. 

In  the  original  volume  describing  the  brachiopods  of  the  Devonian 
of  New  York  a  the  following  localities  are  mentioned  in  which  Spirifer 
disjunctus  occurs,  viz:  Elmira,  Leon,  Painted  Post,  Factoryville, 
Cayuta  Creek,  Chemung  Narrows,  Conewango,  Great  Valley,  Ran- 
dolph, Napoli,  New  Albion,  Chemung,  Bath,  Angelica,  Troupsburg, 
Meadville,  Pa.,  Twentymile  Creek,  Ellington,  Glean,  Covington,  Pa. 

From  these  localities  the  following  species  are  recorded  for  the  num- 
ber of  localities  indicated : 

Table  XXTIa. — Species  listed  from  same  localities  with  Spirifer  disjunctus  in 

New  York  reports. 

Camarotoechia  contracta -   10 

Orthothetes  chemnngensis.  -    -     3 

Athyris  angelica  . -  3 

Prodnctella  hirsuta  and  var -  1  "* 

Sphenotus  contractus 2 

There  are  other  species  mentioned  in  the  published  lists,  but  from 
each  locality  the  number  of  species  is  limited,  rarely  over  20  and 
generally  under  10.  The  collections  show  in  themselves  that  the  con- 
spicuous species  were  gathered,  or  perhaps  the  fine  specimens  only 

a  Palaeontology  New  York,  Vol.  IV,  1867. 


88  COKKELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

were  selected  and  recorded,  the  imperfect  ones  being  left  and  not 
mentioned  in  the  catalogues.  Nevertheless,  the  statistics  give  a  slight 
indication  of  the  prominent  associates  of  Spirifer  disjunctus.  Among 
the  prominent  members  of  the  dominant  list  of  the  species  of  the  fauna 
it  is  safe  to  say  that  the  following  species  frequently  appear,  viz: 

Table  XXIIb. — Conspicuous  species  of  the  Spirifer  disjunctus  fauna. 

Spirifer  disjunctus. 

Camarotcechia  contracta. 

Productella — some  one  of  the  forms  of  the  lachrymosa  or  hirsuta  forms  and 

markings. 
Orthothetes  chemungensis. 
Athyris  angelica. 

Among  the  spirifers  the  typical  Spirifer  (Delthyris)  mesicostalis  with 
coarse  plications  and  distinct  septum  does  not  appear  in  the  Ithaca 
zone,  but  is  common  in  the  Upper  Chemung  zone.  Spirifer  mesi- 
st  rial  is  is  common  in  the  lower  Ithaca  zone;  and  in  the  zone  domi- 
nated by  the  Spirifer  disjunctus  fauna  it  is  represented  by  Spirifer 
(Cyrtia)  alia  or  Spirifer  marcyi  var.,  but  is  rarely  associated  with  a 
pure  Spirifer  disjunctus  t'aunule. 

The  common  Ithaca  spirifer  is  S.  pennatus  var.  posterns.  It  is  often 
called  ' 'mesicostalis ,"  but  generally  has  finer  plications  and  is  always 
without  distinct  septum  in  the  Ithaca  zone,  thus  separating  it  from 
Delthyris  mesicostalis  of  the  typical  Spirifer  disjunctus  fauna. 

The  rhynchonellas  (Camarotozchia)  show  a  definite  succession  of 
species.  The  Ithaca  zone  carries  C.  eximia  and  stephani,  and  occa- 
sionally forms  identified  as  ( '.  contracta;  but  typical  ( '.  contracla,  with 
the  small  number  of  plications,  is  confined  to  the  higher  horizon,  and 
runs  into  the  forms  called  C.  orbicularis  and  C.  sappho  or  C.  alle- 
ghenia  in  the  typical  higher  Chemung.  R.  (Pugnax)  pugn us  is  not 
found  associated  with  the  Spirifer  disjunctus  fauna,  but  is  a  species 
of  the  lower  Ithaca  zone. 

Among  the  productellas  the  forms  called  P.  lachrymosa  and  its 
varieties  do  not  appear  in  the  fan  miles  till  the  disjunctus  stage  is 
reached.  They  are  distinguished  by  their  coarse,  large,  evenly 
rounded  gibbous  form.  Although  these  are  associated  with  the  finely 
hirsute  forms  and  others  marked  on  the  surface  like  P.  speciosa,  the 
form  which  is  generally  identified  as  P.  speciosa  is  an  earlier  form. 

The  Ithaca  form  is  characteristically  Productella  speciosa,  though 
showing  some  variation;  the  small  rounded  spine  bases  not  drawn  out 
so  as  to  be  oblong,  and  the  low  and  pinched  or  narrow  beak,  with  more 
or  less  rounded  cardinal  angles,  are  conspicuous  distinguishing 
features. 

Although  the  original  specimens  named  P.  speciosa  appear  to  have 
come  from  the  western  part  of  the  State  and  a  locality  holding  a  typi- 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  89 

cal  Chemung  fauna,  the  Ithaca  form  is  characteristic  and  much  more 
common  and  has  in  the  later  literatures  become  the  type  of  that 
species. 

These  remarks  will  serve  to  express  the  present  knowledge  regard- 
ingthe  actual  distinguishing  features  of  the  fauna  of  the  typical  Che- 
mung formation.  The  difficulty  found  in  making  the  definition  more 
accurate  comes  from  the  great  uncertainty  as  to  the  precision  with 
which  the  limits  of  the  fauna  have  been  discriminated. 

In  many  reported  Chemung  lists  of  species  uncertainty  is  presented, 
both  as  to  the  identification  of  Spirifer  disjunctus  and  as  to  the  exact 
stratigraphical  horizon  from  which  the  species  came. 

The  present  paper  can  therefore  go  no  further  in  precision  of  defi- 
nition of  this  fauna;  and  attention  is  here  directed  to  the  great  need 
of  more  accurate  statistics  regarding  the  individual  faunules  of  the 
upper  extension  of  the  marine  Devonian  faunas.  These  statistics  can 
be  obtained  by  local  collectors  living  in  regions  of  outcrops  of  Che- 
mung rocks,  who  will  render  a  service  to  science  by  furnishing  accu- 
rate lists  of  the  species,  with  statistics  as  to  the  exact  locality  and 
zone  and  the  relative  abundance  of  the  species  in  each  faunule. 

RECURRENCE  OF    THE    TROPIDOLEPTUS    FAUNA    IN    THE    EPOCH 
OF  THE  SPIRIFER    DISJUNCTUS  FAUNA. 

Report  of  a  recurrent  Hamilton  fauna  in  the  midst  of  the  rocks  of 
the  Ithaca  formation  was  made  in  Bulletin  No.  3  of  the  IT.  S.  Geo- 
logical Survey,  p.  15. 

Mention  was  made  also  of  Tropidoleptus  and  other  Hamilton  species 
occurring  in  Owego  at  a  horizon  high  up  in  the  Chemung.  The  full 
importance  of  these  cases  was  not  appreciated  at  the  time  of  their  first 
announcement.  Recently  the  facts  have  been  stated  in  detail  and 
may  be  restated  here: 

We  have  positive  evidence  of  a  colony  of  the  Tropidoleptus  fauna  within  ;it 
least  50  feet  of  the  typical  horizon  of  the  Chemung  formation  in  Chemung 
County,  and  also  in  the  midst  of  the  Chemung,  or  Spirifer  disjunctus,  fauna  at 
Owego,  as  I  announced  in  1884." 

These  evidences  of  the  Tropidoleptus  fauna  are  so  clear  that  if  we  were  to  find 
them  in  an  isolated  region,  we  should  have  no  hesitation  in  calling  the  forma- 
tion holding  them  Hamilton,  except  that  a  few  species  of  much  later  age  are 
associated  with  them. 

The  typical  species  of  the  Tropidoleptus  fauna  are  such  as — 
Tropidoleptus  carinatus  (abundant). 
Amboccelia  umhonata  (abundant). 
Phacops  rana  (rare,  but  with  several  specimens  I 

a  Bull.  U.  S.  Geol.  Survey  No.  3, 1884,  p.  :.'4;  also  Proc.  Am  Asm,,-.  A.dv.  Sci.,  Vol.  XX  XIV.  L886,p 
226.  This  is  the  stage  A6+ of  the  Tropidoleptus  fauna,  called  in  thai  paper  Middle  Devonian 
fauna  A;  also  p.  230. 


90  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  am. 

It  also  contains  such  characteristic  species  as — 

Spirifer  marcyi,  and  probably  S.  granulosus. 

Cypricardella  bellistriata. 

Goniophora  hamiltonensis. 

Macroclon  hamiltonia?. 

Loxonema  delphicola. 

Modiomorpha  mytiloides. 

The  faunule  from  Owego,  to  which  I  made  reference  in  my  papers  of  1884  and 
1886,  was  so  characteristically  Hamiltonian  in  its  species  that  at  that  time  it  was 
difficult  to  believe  that  the  zone  in  which  it  occurred  was  not  out  of  place.  But 
the  recent  rediscovery  of  the  zone  at  Waverly  by  Dr.  Kindle,  and  a  comparison  of 
the  forms,  leaves  no  doubt  as  to  the  actual  position  of  the  recurrent  Hamilton 
faunule  in  the  midst  of  the  Chemung  formation.  The  species  of  this  faunule  are 
given  in  the  following  list: 

Table  XXIII. — Recurrent  Tropidoleptus  fauna  from  Cemetery  Hill,  Owego, 
Tioga  Count//,  on  side  hill  above  and  southeast  of  the  old  Erie  station,  collected 
by  H.  8.  Williams  (U.  S.  Geological  Survey  station  1130  A).- 


1.  Spirifer  marcyi  var.    ■ 

aa ' 

Hamilton. 

2.  Amboccelia  umbonata 

<l<l 

Marcellus-Chemung. 

3.  Cypricardella  bellistriata 

aa 

Hamilton. 

4.  Tropidoleptus  carinatus 

c 

Hamilton. 

5.  Leiopteria  bigsbyi 

c 

Hamilton. 

6.  Phacops  rana 

r 

Hamilton. 

7.  Productella  speciosa 

r 

Portage-Chemung-Kinderhook. 

8.  Coleolus  acicula 

r 

Genesee. 

9.  Loxonema  delphicola 

r 

Hamilton. 

10.  Camarotcechia  cf .  prolifica 

r 

Marcellus-Hamilton. 

11.  Goniophora  hamiltonensis 

r 

Hamilton. 

12.  Modiomorpha  mytiloides 

r 

Hamilton. 

13.  Spirifer  cf .  granulosus 

rr 

Hamilton. 

14.  Chonetes  setigerus 

rr 

Marcellus- Waverly. 

15.  C.  lepidus 

rr 

Marcellus-Chemung. 

16.  Macrodon  hamiltonia? 

rr 

Hamilton. 

17.  Lingula  sp. 

rr 

18.  Pterinea  sp. 

rr 

19.  Grammysia  sp. 

rr 

20.  Palseoneilo  sp. 

rr 

21.  Aviculopecten  sp. 

rr 

It  will  be  observed  that  of  the  16  species  specifically  identified,  all  but  2  are 
Hamilton  species.  One  of  the  exceptions  is  Productella  speciosa,  which  has  been 
reported  from  Portage,  Chemung,  and  Kinderhook  formations,  and  the  other, 
Coleolus  acicula,  is  a  Genesee  species.  Eleven  of  the  16  have  not  been  hitherto 
reported  from  above  the  Hamilton  formation,  while  the  other  4  range  both  below 
and  above  that  formation. 

On  the  principle  of  specific  identification,  therefore,  this  faunule  belongs  to  the 
genuine  Tropidoleptus  carinatus  fauna,  of  which  it  contains  four  of  the  dominant 
species  of  the  standard  list. 


aa,  abundant;  aa,  very  abundant;  c,  common;  r,  rare;  rr,  very  rare. 


Williams.]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  91 

The  species  of  the  Waverly  fauna  collected  and  identified  by  Dr.  Kindle  are  as 
follows: 

Table  XXIV  .—Tropidoleptus  faunule  as  a  colony  in  Chemung  formation,  Waverly, 
N.  Y.  (1462  B,  U.  S.  Geological  Survey),  identified  by  E.  M.  Kindle  (  1902). 


1.  Tropidoleptus  carinatus 

a' 

1  Hamilton. 

2.  Amboccelia  umbonata 

a 

Marcellus-Chemumg. 

3.  Rhipidomella  vanuxemi 

c 

Cornif erous  [Onondaga]  -Hamilton 

4.  Spirifer  marcyi 

c 

Hamilton. 

5.  Cypricardella  bellistriata 

c 

Hamilton. 

6.  Productella  lachrymosa 

c 

Chemung. 

7.  Delthyris  mesicostalis 

c 

Ithaca-Chemung. 

8.  Camarotcechia  contracta 

r 

Portage- Waverly. 

9.  Schizophoria  cf.  tioga 

rr 

Portage-Chemung. 

10.  Leptodesma  matheri 

rr 

Chemung. 

11.  Glyptodesma  erectum 

rr 

Hamilton. 

12.  Pterinopecten  sp. 

rr 

13.  P.  crenicostatus 

rr 

Chemung. 

14.  Modiomorpha  cf .  concentrica 

rr 

Hamilton. 

15.  Cyrtina  hamiltonensis 

rr 

Up.  Held.,  Ham.,  Portage,  Chemu 

The  commonly  reported  range  by  formations  is  given  in  the  column  on  the  right. 

In  this  faunule,  it  will  be  observed,  the  abundant  and  common  forms  are.  with 
the  exception  of  Productella,  chiefly  found  in  the  Hamilton  formation. 

Nevertheless,  the  faunule  occurs  in  the  rocks  after  the  Spirifer  disjunctus  fauna 
has  occupied  the  region  in  force  with  its  typical  development;  thus  showing  that 
in  time  the  two  faunas  were  coexistent  in  separate  areas  in  their  normal  bionic 
strength.  That  is  to  say,  in  the  areas  of  their  geographic  metropolis,  each  fauna 
maintained  its  bionic  equilibrium  as  expressed  in  frequency  and  dominance  of 
species. 

The  importance  of  this  case  of  recurrence  of  the  Tropidoleptus  fauna  is  so  great 
as  to  call  for  every  precaution  as  to  its  verity.  The  intrinsic  evidence  of  its 
Chemung  horizon  was  not  present  in  the  Owego  faunule.6  There  are  no  species 
there  which  might  not  occur  as  low  as  the  Ithaca  group.  But  the  faunule  col- 
lected at  Waverly  contains  Delthyris  mesicostalis  with  a  distinctly  strong  median 
septum,  which  is  wanting  or  very  slightly  developed  in  the  specimens  of  the 
Ithaca  formation;  also  a  single  specimen  of  Schizophoria  tioga,  nothing  like 
-which  is  known  in  the  typical  fauna  of  the  Ithaca  formation.  The  Productella 
lachrymosa  is  not  so  strongly  of  the  true  lachrymosa  type  as  to  make  it  certain 
that  it  may  not  be  an  extreme  variation  of  Productella  speciosa.  The  leptodesmas 
are  so  variable  that  the  form  L.  matheri  is  not  conclusive  of  post-Ithaca  stage. 

In  my  collections  from  the  Waverly-Chemung  cliffs,  however,  Tropidoleptus 
was  discovered  above  the  first  appearance  of  Spirifer  disjunctus  and  other  typical 
members  of  the  Spirifer  disjunctus  fauna.  These  facts  are  intrinsic  evidence, 
therefore,  that  the  combination  of  species,  so  much  like  the  typical  Tropidoleptus 
carinatus  fauna  of  the  Hamilton,  is  here  present  in  a  part  of  the  rock  section 
occupied  in  general  by  a  typical  Spirifer  disjunctus  fauna. 

The  fact  that  the  combination  of  species  is  the  normal  combination  seen  in  the 
undisputed  Hamilton  formation  shows  that  its  equilibrium  had  not  been  dis- 
turbed, and  therefore  that  the  life  history  of  the  fauna  of  the  Hamilton  forma- 


tter, abundant;  c,  common;  r,  rare;  rr,  very  rare. 

b Since  the  above  was  written  I  have  examined  the  Owego  locality  and  another  locality  wesl 
of  Waverly  and  have  proved  beyond  controversy  that  this  recurrent  Hamilton  fauna  occurs  nol 
only  well  above  Spirifer  disjunctus,  but  several  hundred  feet  above  the  base  of  the  rocks  along 
Chemung  Narrows,  constituting  the  typical  exposure  of  the  Chemung  formation  of  Ball's  Reporl 
of  1843.    (Part  IV,  Geology  New  York  State  p.  252.).— H.  8,  W. 


92  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  silo. 

tion  had  not  ceased,  while  the  faunas  above  and  below  in  the  cliffs  in  Chemung 
Narrows  is  evidence  that  the  geological  horizon  is  that  of  the  typical  Chemung 
formation.  The  lapping  of  faunas  of  the  same  kind  seems  to  be  established  by- 
evidence  beyond  dispute,  and  correlations  must  be  made  with  recognition  of  such 
a  possibility  in  cases  where  the  direct  evidence  of  the  fact  may  be  wanting. 

When  we  attempt  to  correlate  formations  with  this  knowledge  before  us  it  is 
evident  that  the  life  period  of  a  fauna  is  not  what  it  appears  to  be  in  any  partic- 
ular section.  Whenever  the  succession  is  sharply  defined  by  the  stopping  of  one 
fauna  and  the  abrupt  beginning  of  another,  in  full  or  decided  strength,  the  evi- 
dence should  be  interpreted  as  positive  that  the  boundary  between  the  two  con- 
secutive formations  does  not  make  the  end  of  one  fauna  and  the  beginning  of  the 
succeeding  one.  It  is  to  be  interpreted  rather  as  only  a  well-advanced  stage  into 
the  later  one  and  the  vigorous  period  of  persistence  of  the  other.  This,  inter- 
preted into  comparative  terms,  would  result  in  showing  that  the  two  faunas  lap 
over  each  other  in  time. 

My  studies  convince  me  that  this  is  frequently  the  case  in  respect  to  the  bound- 
ary lines  of  our  formations.  The  abrupt  transition  from  one  formation  to 
another  with  a  different  fauna  is  convincing  evidence  that  the  abruptness  of  the 
change  in  fossils  is  due  either  to  absence  of  strata  (i.  e. .  an  apparent  or  concealed 
unconformity)  or  else  to  migration  of  the  faunas  across  the  area. 

This  principle  must  be  recognized  in  making  correlation,  if  we  would  reach 
correct  interpretation  of  the  facts/' 

MARINE  FAUNA  ABOVE  ONEONTA  SANDSTONE  OF  EASTERN  NEW 

YORK. 

Accepting  Table  XXI  as  an  approximately  correct  list  of  the  domi- 
nant species  of  the  Spirifer  clisjunctus  fauna,  as  it  existed  in  the 
typical  area  of  its  distribution,  what  relation  does  the  fauna  occurring 
above  the  Ithaca  fauna  in  the  eastern  part  of  the  State  bear  to  it? 

In  opening  the  discussion  of  this  question  it  maybe  noted  that 
among  the  20  dominant  species  listed  in  'Fable  XXI  (the  Spirifer 
disjunctus  fauna),  three  are  reported'  by  Gra ban  from  the  Hamilton 
formation  of  Eighteenmile  Creek.  These  are  Ambocoelia  umbonata, 
Chonetes  sciiulus,  and  Palczoneilo  constricta.  The  same  species,  and 
the  variety  arctistriatus  of  Orthothetes  chemungensis  are  reported  from 
the  Hamilton  faunules  of  the  Cayuga  Lake  section  by  Cleland.  All 
four  of  these  species  are  specifically  identified  by  Prosser  in  the 
Hamilton  faunules  of  eastern  New  York  and  Pennsylvania. 

Removing  from  the  list  these  recurrent  species  (viz.,  Ambocalia 
umbonata,  Orthothetes chemurxje us is,  Chonetes  sciiulus,  and  PalcBoneilo 
constricta),  as  occurring  also  in  the  fauna  of  the  Hamilton  formation 
below,  the  remaining  16  will  stand  as  characteristic  species  as  well 
as  dominant  representatives  of  the  typical  fauna  of  the  Chemting 
formation. 

In  the  sections  in  Chenango  and  Otsego  counties  above  the  Oneonta 
sandstone  occasionally  a  few  species  occur  which  have  led  to  classify- 
ing the  beds  holding  them  in  the  Chemung  formation. 

In  the  recent  revision  of  the  geological  mapping  of  that  part  of  the 
State  the  State  paleontologist  appears  to  have  adopted  the  Oneonta 

"Am.  Jour.  Sci.,  4th  series,  Vol.  XIII,  1902,  pp.  428-431. 


willi'ams]  FAUNAL    DISSECTION    OF    THE    DEVONIAN.  93 

formation  as  the  formational  plane  of  division  between  the  Ithaca 
and  Chemung  formations.     But  an  examination  of  the  faunas  con- 
cerned makes  it  clear  that  the  classification  is  more  strongly  influ- 
enced by  the  lithological  than  the  paleontological  evidence.0 
Regarding  this  point  Prosser6  says: 

After  reviewing  the  results  obtained  by  different  investigators  of  this  problem 
of  the  sexiaration  of  the  Chemung  and  Portage  and  the  Chemung  and  Oneonta 
formations  in  the  central  part  of  southern  New  York,  the  facts  seem  to  justify 
the  conclusion  that  the  Chemung  begins  with  the  Orthis  im pressa  fauna  overlying 
the  Oneonta  formation.  The  thickness  of  the  formation  composing  the  Chenango 
Valley  section,  ranging  from  the  base  of  the  Marcellus  shale  in  Sangerfield  Town- 
ship, Oneida  County,  up  into  the  Chemung,  on  top  of  the  hill  in  Fenton  and  Kirk- 
wood  townships,  Broome  County,  to  the  northeast  of  Binghamton.  is  approxi- 
mately as  follows:  Estimating  the  dip  for  the  northern  part  of  the  Chenango 
Valley  to  be  60  feet  to  the  mile,  we  would  have  a  thickness  of  about  1,500  feet  for 
the  Marcellus  and  Hamilton  formations.  To  the  east  of  Smyrna  there  are  per- 
haps 25  feet,  representing  the  Tully  limestone  and  Genesee  slate.  The  Sherburne 
formation  is  250  feet,  the  Ithaca  500  feet  or  more,  and  the  Oneonta  500  feet  thick, 
while  for  the  Chemung,  from  Greene  to  the  top  of  the  hill  south  of  Port  Crane, 
calling  the  dip  60  feet  per  mile,  there  are  1,225  feet,  which  result  agrees  quite  well 
with  the  record  of  the  well  drilled  at  Binghamton. 

Generalized  section  giving  thickness  of  the  Chenango  Valley  formations. 

Feet.  Feet. 


Chemung  „.  .  1,225 

Oneonta 550 

Ithaca '_'_      500  f 


Sherburne 250 

Genesee  and  Tully 25 

Hamilton  and  Marcellus 1,500  (?) 


This  solution  is  a  practical  one  for  the  particular  region.  For  the 
purpose  of  mapping  the  middle  eastern  part  of  New  York  the  Oneonta 
sandstones  may  no  doubt  be  recognized  as  a  formation,  and  they  form 
a  convenient  separating  line  for  formations. 

When,  however,  the  statement  is  made  that  "in  the  vicinity  of 
Greene  *  *  *  the  Oneonta  beds  are  overlaid  by  a  typical  and 
highly  developed  Chemung  fauna,"''  the  necessity  for  using  some  o1  her 
term  for  the  name  of  a  fauna  than  the  geographical  name  of  a  forma- 
tion becomes  apparent,  for  the  fauna  in  Greene  County  referred  to 
doos  not  represent  the  Spirifer  disjunctus  fauna,  which  is  character- 
istic of  the  Chemung  formation  in  its  typical  geographical  area.  Sta- 
tistics regarding  the  composition  of  the  fauna  following  the  Oneonta 
formation  in  eastern  New  York  are  given  by  Prosser  in  two  papers,** 
an  examination  of  which  will  illustrate  this  fact. 


flSee  Report  of  field  work  in  Chenango  County,  by  J.  M.  Clarke:  Thirteenth  Ann.  Rept.  New 
York  State  Geologist,  1893.  Vrol.  I, 

''The  classification  and  distribution  of  the  Hamilton  and  Chemung  series  of  central  and  east 
ern  New  York,  Part  I,  by  C  S.  Prosser:  Fifteenth  Ann.  Rept.  New  York  State  Geologist,  ]»p 
165-166. 

(•Clarke,  loc.  cit.,  p.  557. 

^Classification  and  distribution  of  the  Hamilton  and  Chemung  series  "f  central  and  eastern 
New  York,  Part  II,  by  Charles  S.  Prosser:  Fifteenth  Ann.  Rept.  New  York  State  Geologist,  L895, 
pp.  87-222.  Classification  and  distribution  of  the  Hamilton  and  Chemung  series  of  ceni  raJ  and 
eastern  New  York,  Part  II,  by  Charles  s  Prosser:  Seventeenth  Ann.  Rept.  New  York  State 
Geologist,  1899,  pp.  67-327. 


94  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

There  are  29  faunnles  occurring  above  the  horizon  of  the  Oneonta 
formation,  whose  specific  composition  is  analyzed.  The  faunules  are 
from  the  counties  of  Chenango,  Broome,  and  Delaware,  New  York 
State.  The  species  of  the  characteristic  Chemung  fauna  reported  as 
present  in  these  29  faunules  of  this  region  are  given  in  Table  XXV. 

Table  XXV. — Spirifer  disjunctus  fauna:    Characteristic  representatives  of  the 
fauna  reported  in  the  eastern  counties  of  New  York  and  Pennsylvania. 

1.  Spirifer  mesistrialis .  _     6     4.  Camarotoechia  contracta 1 

2.  Productella  lachrymosa 8     5.  Spirifer  disjunctus 1 

3.  Delthyris  mesicostalis (/  9 

As  to  the  occurrence  of  Productella  lachrymosa,  it  was  also  reported 
by  Clarke  from  the  Juliand  Hill  locality  in  Greene  Township,  Che- 
nango County/' 

Prosser,  referring  to  the  identification  of  the  same  species  in  a 
faunule  from  the  extreme  southwestern  corner  of  the  township  (his 
station  XXXVI  A  1),  says: 

Probably  some  of  these  specimens  should  be  cf.  P.  speciosa  of  Ithaca,  but  the 
pustules  are  coarser  than  in  this  species.  So  identified  by  Clarke  in  Thirteenth 
Annual  Report,  page  543. ' 

Dr.  Clarke,  referring  to  the  Juliand  Hill  faunule,  says: 

Fossils  are  abundant  throughout  these  shales  and  are  of  typical  Chemung 
expression.  <l 

In  no  other  faunule  of  the  Chenango  localities  reported  by  Dr. 
Clarke  in  the  paper  cited  is  this  species  mentioned,  and  in  none  of 
his  faunule  lists  are  any  species  of  the  characteristic  Chemung  list 
reported,  not  already  mentioned  in  the  list  above/ 

The  one  record  of  Camarotozchia  contracta  made  by  Prosser  is  from 
the  Pixley  Mill  faunule  north  of  Afton.  The  only  identification  of 
Spirifer  disjunctus  by  Prosser  is  in  a  faunule  (XLII  B  5)  in  the  sec- 
tion southwest  of  Port  Crane  near  the  top  of  the  hill.  This  obser- 
vation led  him  to  remark: 

The  occurrence  of  this  characteristic  Chemung  species  conclusively  proves  that 
the  rocks  near  the  top  of  the  high  hill  south  of  Port  Crane  are  in  the  Chemung 
formation./ 

In  order  to  test  the  equivalency  of  this  fauna  it  will  be  necessary 
to  make  a  more  deliberate  examination  of  its  content,  and  to  study 
the  bionic  values  which  the  several  species  hold  in  the  general  corpo- 
rate fauna  as  a  whole. 

We  have  the  carefulty  collected  statistics  of  29  faunules  reported 
by  Prosser  from  this  so-called  Chemung  formation  of  the  eastern 
counties.     The  total  number  of  species   positively  identified  is  65, 

a  Three  times  positively. 

&The  stratigraphic  and  faunal  relations  of  the  Oneonta  sandstones  and  shales,  the  Ithaca 
and  the  Portage  groups  in  central  New  York,  by  John  M.  Clarke:  Fifteenth  Ann.  Rept.  State 
Geologist  New  York,  1895,  pp.  2T-81. 

c  Fifteenth  Ann.  Rept.  State  Geologist  New  York,  p.  152. 

d Thirteenth  Ann.  Rept.  State  Geologist  New  York,  p.  543. 

e  Table  XXV.  above. 

/Fifteenth  Ann.  Rept.  State  Geologist  New  York,  p.  160. 


WILLIAMS.] 


EAUNAL    DISSECTION    OF    THE    DEVONIAN. 


95 


there  are  23  more  named  with  a  query,  and  31  entries  in  whieh  only 
generic  or  more  general  identification  was  made.  Of  this  total  of  65 
species  27  species  are  also  listed  in  the  faunules  of  the  Hamilton 
formation;  they  are  given  in  Table  XXVI. 

Table  XXVI.—  Species  of  the   Tropidoleptus  ran' iki his   fauna    occurring  above 
the  Oneonta  sandstone  in  eastern  New  York. 


1.  Amboceelia  umbonata. 

2.  Atrypa  reticularis. 

3.  Camarotcechia  congregata. 

4.  Chonetes  scitulus. 

5.  C.  setigerus. 

6.  Coleolus  tenuicinctum. 

7.  Cyrtina  hamiltonensis. 

8.  Grammysia  bisulcata. 

9.  G.  circ/ularis. 

10.  G.  subarcuata. 

11.  Leda  di versa. 

12.  Leiopteria  bigsbyi. 

13.  Loxonema  delphicola. 


15.  Lunulicardium  fragile. 

16.  Cypricardella  bellistriata. 

17.  C.  complanata. 

18.  C.  gregaria. 

19.  Nuculites  cuneiformis. 

20.  N.  oblongatus. 

21.  Orthis  (Schizophoria)  impressa. 

22.  O.  undulata. 

23.  Palaeoneilo  plana. 

24.  P.  constricta. 

25.  Spirifer  granulosus. 

26.  Stropheodonta  deniissa. 

27.  Tropidoleptus  carinatus. 


.14.  L.  hamiltoniae. 

Five  of  these  (Nos.  1,  20,  24,  25,  27)  are  found  in  the  list  of  the  12 
most  dominant  species  of  the  typical  Hamilton  formation  of  eastern 
New  York  (p.  51). 

Of  this  list,  23  are  also  reported  from  the  underlying  Ithaca  forma- 
tion     The  5  not  listed  by  Prosser  in  the  Ithaca  are— 

Stropheodonta  deniissa. 

Orthis  (Schizophoria)  impressa. 


Grammysia  circularis. 
Loxonema  delphicola. 
L.  hamiltoniae. 


Both  Stropheodonta  deniissa  and  Schizophoria  impressa  are  in  the 
Ithaca  formation  of  Ithaca.  Their  omission  from  the  Ithaca  formation 
in  the  eastern  counties  may  be  only  accidental,  but  they  certainly  do 
not  furnish  means  of  discrimination  between  the  Ithaca  and  Chemung 
formations. 

There  are  also  eight  species  which  are  not  recorded  in  the  Hamilton, 
but  are  recorded  in  both  the  Ithaca  and  Chemung  lists  of  the  same 
region.     They  are  recorded  in  Table  XXVII. 

Table  XXVII. — Species  in  "  Chemung'''  list  which  arc  also  in  Hie  Ithaca,  hut  not 
in  the  Hamilton  formation. 


1.  Camarotcechia  stephani. 

2.  Cyclonema  multilara. 

3.  Grammysia  elliptica. 

4.  G.  nodocostata. 


5.  Leiorhynchus  mesicostale. 

6.  Delthyris  mesicostalis. 

7.  Spirifer  rnesistrialis. 

8.  S.  pennatus  posterus. 

Paloeoneilo  filosa  might  be  added  to  the  above  table.  It  occurs  in 
the  "Chemung"  list  and  in  the  Portage,  but  not  in  the  Ithaca  or 
Hamilton  lists. 

Two  of  the  species  in  Table  XXVII — Spirifer  rnesistrialis  and 
Delthyris  mesicostalis — are  among  the  characteristic  and  dominant 
species  of  the  standard  Spirifer  dis/ a  nctus  fauna  (see  Table  XXI).  So 
far  as  their  evidence  bears  upon  the  case,  their  appearance  in  1  lie 


96  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

Ithaca  formation,  which  has  been  demonstrated  to  lie  below  the  Che- 
mung in  the  Ithaca  section/'  is  opposed  to  the  supposition  that  the 
horizon  now  under  investigation  is  as  high  as  the  typical  Chemung 
formation  of  western  New  York. 

Finally,  there  are  25  species  which  have  not  been  recorded  in  the 
region  below  the  base  of  what  is  there  called  the  Chemung  formation. 
These  are  tabulated  in  Table  XXVIII. 

Table  XXVIII. — Species  which  occur  above  the  Oneonta  formation  but  not  in  the 
Ithaca  formation  of  the  eastern  counties. 


*  1.  Bellerophon  msera 2 

2.  Camarotcechia  eontracta. 

3.  Edmondia  philipi. 

4.  Ectenodesma  birostratum. 


*  R 


Goniophora  subrecta 


15.  Onychodus  hopkinsi. 

16.  Palaeoneilo  brevis  var.  quad- 

rangularis. 

*17.  P.  brevis.,  3    3 

18.  Pleurotomaria  itys. 

*19.  Productella  lachrymosa 8 

*20.  Pugnax  pugnus  . 3 

21.  Schizodus  gregariux. 

22.  S.  chemungensis. 
*23.  S.    chenmngensis   var.    quad- 

rangularis  .  _ . 3 


G.  Grammysia  communis. 

7.  Holonema  rugosa. 

8.  Leiopteria  rafinesquii. 
*  9.  Leiorhynchus  globuliforme  ..   (.»     1 

*10.  Leptodesma  sociale . . 4    3 

*11.  Lyriopecten  priamus 3 

*12.  L.  tricostatus  _ .  4    2      24.  Sphenotus  contractus. 

*13.  Modiomorpha  quadrula 4  25.  Spirifer  disjunctus. 

14.  Mytilarca  carinata. 

The  species  starred  arc  mentioned  in  more  than  onefaunnle;  those 
not  starred  were  positively  identified  but  a  single  time  in  all  the 
faunules  analyzed.  On  the  right  of  the  starred  species  are  numbers 
indicating,  first,  the  number  of  positive  identifications,  then  the 
number  of  doubtful  specific  identifications.  When  the  number  of 
doubtful  identifications  is  large,  variation  is  probably  great. 

Only  3  of  these  25  species  belong  to  the  standard  list  of  dominant 
species  of  the  western  Chemung  (see  Table  XXI).     These  are: 

Spirifer  disjunctus. 

Productella  lachryim >sa. 

Camarotoechia  contracta. 

As  has  already  been  said,  the  first  and  last  of  these  are  reported 
but  once.  On  the  other  hand,  the  fauna  contains  Pugnax  pugnus, 
which  is  characteristic  of  the  typical  Ithaca  fauna,  but  does  not 
belong  to  the  typical  Chemung  fauna  of  western  New  York. 

On  the  other  hand,  the  following  table   (Table  XXIX)  shows  a 
prominence  of  species  which  in  the  western  New  York  Devonian  are 
characteristic  of  an  earlier  stage  in  faunal  development  than  that  of 
the  Spirift  r  disjunctus  fauna. 
Table  XXIX. — Dominant  species  above  the  Oneonta  not  confined  to  the  horizon 

of  the  Chemung  formation  in  western  New  York. 
Spirifer  pennatus  posterns.  Delthyris  mesicostalis. 

S.  mesistrialis.  Pugnax  pugnus. 

Camarotoechia  stephani.  Chonetes  setigerus. 

Cypricardella  gregaria.  Camarotoechia  eximia. 

Tropidoleptus  carinatus.  Palaeoneilo  constricta. 

"Bull.  U.  S.  Geol.  Survey  No.  3,  1884,  p.  28. 


CHAPTER  IV. 

SHIFTING    OF    FAUNAS. 

EVIDENCE     OF     SHIFTING      OF      FAUNAS      ASSOCIATED      WITH 
DEPOSITION   OF  ONEONTA   SANDSTONE. 

Ill  considering  the  evidence  contained  in  the  tables  of  statistics 
already  presented,  it  is  important  to  note  the  following  points:  The 
strata  lying  above  the  Oneonta  sandstone  and  below  the  Catskill,  in 
the  eastern  counties  of  New  York,  contain  a  fauna  in  which  there  are 
27  species  of  the  Tropidoleptus  carinatus  fauna,  5  of  which  are  among 
its  most  characteristic  12,  and  25  of  which  are  reported  from  genuine 
Ithaca  formation  strata.  The  fauna  contains  8  species  which  are 
found  in  the  underlying  Ithaca  formation,  but  have  not  been  recorded 
for  the  Hamilton  of  this  region;  3  of  these  are  in  the  list  of  dominant 
species  of  the  Productella  speciosa  fauna.  Finally,  there  are  25  species 
not  recorded  from  the  formations  below  in  the  same  region,  4  of  which 
are  among  the  dominant  species  of  the  Spirifer  disjunctus  fauna,  but 
only  one  of  these  forms  is  at  all  dominant  in  the  eastern  fauna  under 
investigation.  a 

The  evidence  points  clearly  to  a  position  intermediate  between  the 
typical  faunas  of  the  Hamilton  and  Chemung  formations.  That  the 
rocks  are  younger  than  the  Hamilton  formation  is  shown  both  by 
stratigraphical  evidence  and  by  the  occurrence  of  species  that  have 
never  been  discovered  in  the  Hamilton  formation.  That  they  are  not 
of  the  same  horizon  as  the  Chemung  formation  containing  the  pure 
Spirifer  disjunctus  fauna  is  shown  by  the  absence  of  most  of  the 
dominant  species  of  that  fauna,  as  well  as  by  the  strong  representa- 
tives of  typical  species  of  the  Tropidoleptus  carina! us  fauna;  and 
that  they  are  later  than  the  typical  Ithaca  formation  is  shown  by  the 
presence  of  a  few  forms  not  occurring  so  low  as  the  Ithaca  formation 
of  the  central  and  western  parts  of  the  State. 

The  paleontological  statistics  are  thus  conclusive  in  demonstrating 
the  intermediate  place  of  the  post-Oneonta  fauna  between  the  typical 
Productella  speciosa  fauna  of  the  Ithaca  formation,  and  the  Spirifer 
disjunctus  fauna  of  the  Chemung;  but  it  does  not  follow  that  the 
rocks  are  intermediate,  and  therefore  not  represented  in  either  the 
Portage  or  Chemung  formations  farther  west.  The  exact  strati- 
graphical  equivalency  may  be  shown  by  a  close  study  of  the  particular 
local  characteristics  of  the  faunules  themselves. 

This  temporary  phase  of  the  general  fauna  of  the  zone  following 

«See  Tables  XXV  to  XXIX. 

Bull.  210—03 7  !>7 


98  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

the  Oneonta  sandstone  was  recognized  and  named  in  1886 a  as  the 
"Leiorhynchus  globuliformis  stage  of  the  Middle  Devonian  fauna." 
The  gibbous  form  of  Leiorhynchus,  under  the  name  Atrypa  globuli- 
formis, was  noted  by  Vanuxem  as  existing  in  myriads  in  the  "Che- 
mung group"  of  the  third  district,  "numerous  localities  abounding 
with  it."6 

The  close  relationship  between  the  species  so  abundant  in  the  are- 
naceous strata  overlying  the  Oneonta  sandstones  of  Chenango  and 
Otsego  counties  and  the  common  flattened  form  Leiorhynchus  mesi- 
costale  was  recognized  by  Hall.c 

The  presence  of  the  species  in  the  Ithaca  formation  was  noted  in 
1884, d  also  the  fact  that  in  the  rocks  about  Ithaca  the  form  called 
Leiorhynchus  mesicostale  was  found  in  the  softer  argillaceous  shales, 
"while  in  the  more  arenaceous  beds  the  convex  forms  L.  globuli- 
forrne  and  L.  kellogi  appear."  The  great  variability  of  the  specimens 
in  any  handful  led  to  the  belief  there  expressed — 

that  the  representatives  of  the  genus  Leiorhynchus,  found  in  the  Devonian  of  New 
York  at  least,  offer  no  better  claim  to  specific  distinction  than  do  the  various 
forms  of  Atrypa  reticularis,  although  the  variations  of  form  and  the  relative  prev- 
alence of  certain  variations  are  valuable  and,  we  believe,  sensitive  indications 
of  changed  conditions  of  environment. 

The  association  of  gibbosity  of  form  with  sandy  sediments  gave 
occasion  for  expecting  the  species  to  appear  in  the  sediments  follow- 
ing the  Oneonta  sandstone  in  the  Chenango  Valley,  and  that  this 
species  should  appeal-  there  in  place  of  Leiorhynchus  mesicostale 
was  looked  upon  not  as  indicative  of  a  new  species,  but  as  evidence 
of  changed  conditions  of  environment  modifjdng  varietally  the  com- 
mon Ithaca  form. 

Another  fact  has  been  observed  in  the  course  of  these  studies — 
Leiorhynchus  occurs  very  often  in  the  rocks  among  the  first  species  of 
brachiopods  to  appear  in  running  up  a  section  after  a  barren  place  in 
the  strata.  This  was  interpreted  as  an  indication  that  the  genus  was 
adapted  to  live  in  conditions  unfavorable  to  the  life  of  most  of  the 
brachiopods.  It  was  noticed  in  the  Chenango  Valley  region  that  Lei- 
orhynchus  globuliforme  was  among  the  earlier  species  to  appeal* 
above  the  sands  and  flags  (nearly  barren  of  marine  invertebrates) 
above  the  horizon  of  the  Oneonta  sandstone.  The  fact  that  the  spe- 
cies appeared  in  the  Ithaca  formation  associated  with  the  characteris- 
tic species  of  that  formation,  and  was  particularly  associated  with  the 
hard  sandstone  beds,  which  were  distinctly  purple  in  color,  led  to  the 
suspicion  that  this  Leiorhynchus  globuliforme  fauna  was  a  represen- 
tative of  the  Productella  speciosa  fauna  of  the  Ithaca  formation,  but 
a  little  later  in  age. 

This  theory  of  a  shifting  of  the  fauna  across  central  New  York  from 

aProc.  Am.  Assoc.  Adv.  Sci..  Vol.  XXXIV,  p.  226. 
6  Geology  of  Third  District  of  New  York,  p.  182. 
c  Paleontology  New  York,  Vol.  IV,  p.  364. 
tfBull.  U.  S.  Geol.  Survey  No.  3,  p.  16. 


WILLIAMS. 


SHIFTING    OF    FAUNAS.  99 


the  east  toward  the  west  during  the  time  of  the  sedimentation  of 
the  Portage  and  Ithaca  formations  of  the  Cayuga  Lake  meridian 
was  suggested  by  the  fact  that  in  the  neighborhood  of  Ithaca,  on 
passing  upward  from  the  Genesee  shale,  there  is  an  increase  of 
species  of  the  Tropidoleptus  fauna  with  the  withdrawal  of  the  Portage 
species.  The  shifting  was  reversed  after  the  center  of  the  Ithaca 
formation  was  passed,  as  was  shown  by  the  reappearance  of  the 
species  of  the  Portage  formation  (in  reverse  order)  on  ascending  the 
strata,  until  above  the  Ithaca  formation,  with  its  dominant  marine 
invertebrate  fauna,  came  several  hundred  feet  of  sediments  quite 
similar  to  the  typical  Portage  of  western  New  York  and  holding  the 
Cardiola  speciosa  fauna. 

This  shifting  of  the  fauna  first  westward  and  then  eastward  was 
such  as  to  make  the  true  succession  of  the  faunas  Lake  a  wedge-shaped 
position  in  the  sediments  rather  than  make  a  continuous  superposi- 
tion of  formations  in  one  column.  The  Oneonta  formation  pushed 
westward  into  the  midst  of  the  Ithaca  formation  of  Ithaca,  and  as  it 
ceased  as  a  formation,  by  the  withdrawal  eastward  again  of  the 
peculiar  kind  of  sedimentation,  the  Ithaca  formation  also  pushed 
eastward,  but  the  fauna  in  the  latter  expressed  a  later  stage  of  evolu- 
tion in  Chenango  County  than  in  Tompkins  County. 

Taking  this  view  of  the  case  the  Oneonta  formation  is,  stratigraph- 
ically,  at  the  same  horizon  as  the  middle  of  the  Ithaca  formation  of 
the  Ithaca  section,  which  is  also  at  the  same  horizon  as  the  midst  of  the 
Portage  formation  of  the  Genesee  Valley  section.  The  fossiliferous 
zone  above  the  Oneonta,  in  Chenango  and  Otsego  counties,  is  the  strati- 
graphical  equivalent  of  the  barren  300  or  400  feet  of  the  Ithaca  sec- 
tion and  the  fossiliferous  beds  of  Caroline,  which  lie  between  the 
fossiliferous  Ithaca  formation  with  the  Produciella  speciosa  fauna 
and  the  Chemung  formation  with  the  Spirifer  disjunctus  fauna. 

The  geographical  shifting  of  faunas  coincidently  with  the  accumu- 
lation of  sediments  not  only  is  consistent  wit li  all  I  he  facts  which 
have  so  far  come  to  light,  but  there  is  no  other  theory  advanced  by 
which  the  bewildering  confusion  in  the  relations  of  the  faunas  of  this 
region  is  satisfactorily  accounted  for. 

The  place  of  the  Oneonta  sedimentation  is  recognized  in  ihe  sand- 
stones and  flags  in  the  midst  of  the  Ithaca  format  ion,  and  1  he  Oneonta, 
by  its  becoming  thicker  and  more  strongly  marked  on  passing  east- 
ward in  Chenango  and  Otsego  count  ies,  is  seen  to  have  its  origin  from 
that  direction. 

The  black  shales  of  the  Genesee  and  the  following  line  mud  shales 
of  the  Portage  of  western  New  York  containing  the  Cardiola  fauna 
(Glyptocardia  speciosa)  thin  out  eastward;  but  the  proposition  that 
they  occupy  the  place  of  the  Portage  and  Ithaca  formations  of  the 
central  part  of  the  State,  in  which  is  a  fauna  rich  in  species  of  the 
Tropidoleptus  fauna,  is  proved  by  the  statistics  collected  by  Messrs. 
Prosser  and  Clarke. 


100  COERELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

The  difficulty  found  in  discussing  this  problem  has  been  due  in 
large  measure  to  the  lack  in  common  usage  of  any  way  to  deal  with 
the  fauna  independently  of  the  name  and  classification  of  the 
geological  formation  to  which  it  is  said  to  belong. 

In  the  present  case,  in  order  to  treat  of  the  subject  in  hand  with 
the  nomenclature  already  in  use,  it  is  necessary  to  say  that  the  rocks 
and  their  fossils  appearing  in  the  section  of  Chenango  and  adjacent 
counties,  above  the  Oneonta  sandstone,  are  either  Ithaca,  Oneonta,  or 
Chemung.  There  seems  to  be  no  other  way  of  designating  them;  the 
use  of  the  word  transition  is  only  an  avoidance  of  decision.  But  if  one 
speak  of  the  formation  as  Chemung,  the  necessity  arises  of  assuming 
the  fauna  to  be  equivalent  to  some  part  of  the  fauna  of  the  Chemung 
formation  where  typically  exhibited.  This,  as  has  been  shown,  is  not 
correct,  if  by  the  ' '  typical  exhibition  "  be  meant  a  case  in  which  the  sep- 
aration between  the  Ithaca  and  Chemung  faunas  is  sharply  defined. 
If  a  case  be  taken  in  which  the  mingling  of  the  two  faunas  is  evident, 
it  is  not  properly  a  typical  exhibition.  But  in  the  list  of  species  from 
these  rocks  in  Greene  Township,  Chenango  County,  there  is  an  undis- 
puted mingling  of  a  large  number  of  species  of  the  standard  Tropi- 
doleptus  fauna  with  a  considerable  number  of  species  of  the  standard 
Spirifer  disjunctus  fauna,  and  a  still  larger  number  of  species  whose 
most  central  stratigraphical  position  is  in  the  standard  Ithaca  for- 
mation. 

If  now  we  are  to  deal  with  the  formations  as  such,  the  evidence 
seems  to  be  very  strong  for  the  opinion  that  the  part  of  the  actual  col- 
umn of  the  Genesee  section  of  western  New  York,  called  the  Portage 
formation  in  the  reports,  when  followed  stratigraphically  eastward  is 
represented  not  only  by  the  Oneonta  formation  of  Otsego  and  adja- 
cent counties  in  the  eastern  part  of  the  State,  but  by  the  f ossifer- 
ous beds  lower  down,  and  by  some,  at  least,  of  the  fossiliferous  beds 
following  the  Oneonta. 

Even  if  we  were  to  suppose,  with  Dr.  Clarke,  that  the  Oneonta  sand- 
stone is  the  formational  equivalent  of  the  "Portage  sandstone, "a 
this  does  not  dispose  of  the  essential  problem;  because  the  equiva- 
lency does  not  include  likeness  of  species  in  the  two  formations. 

The  fauna  in  the  beds  below  the  Oneonta  sandstone  is  more  diverse 
from  the  fauna  immediately  preceding  the  Portage  sandstone  of  west- 
ern New  York  than  it  is  from  the  fauna  preceding  the  Genesee  shale 
of  the  same  column.  The  fauna  following  it  is  also  less  like  the  fauna 
following  the  Portage  sandstone  than  it  is  like  the  fauna  of  the  Ithaca 
formation,  which  is  known  to  be  stratigraphically  below  it.  If  the 
formational  equivalency  were  in  fact  as  Clarke  supposed  it  to  be,  the 
term  equivalency  would  not  carry  with  it  the  meaning  that  the  beds 
were  deposited  at  the  same  epoch  of  geological  time.6 

The  actual  tracing  of  the  beds  step  by  step  across  from  Otsego  to 
Allegany  County  would  settle  the  question  as  to  time  equivalency, 

a  Thirteenth  Ann.  Rept.  State  Geologist  New  York,  1893.  p.  557.  '->  See  p.  117. 


Williams.]  SHIFTING    OF    FAUNAS.  101 

but  so  far  as  such  work  lias  already  been  carried  the  evidence  is  all 
against  the  supposition  that  the  sandstone  of  the  Otsego  seel  ion  would 
be  a  sandstone  in  the  Allegany  County  section.  This  is  borne  out 
in  the  special  case  of  the  Oneonta,  which  is  lost  as  a  red  sandstone 
mass  before  reaching  Tompkins  County. 

We  are  therefore  forced,  by  the  evidence  before  us,  to  conclude 
that  litliological  characters,  which  constitute  the  basis  of  discrimination 
of  the  geological  formations  as  units,  not  only  can  not  be  relied  upon  to 
discriminate  time  equivalency,  but  uniformity  of  litliological  constitu- 
tion must  be  regarded,  in  some  cases  at  least,  as  positive  evidence  of  non- 
equivalency  in  time.  This  rule  is  applicable  whenever  the  formation 
is  traced  at  right  angles  to  the  original  shore  line  along  which  the 
sediments  were  deposited.  The  exception  to  the  working  of  the  rule 
is  in  those  cases  where  the  formation  is  traced  in  a  line  parallel  to  the 
original  shore  line.  In  such  a  case  sedimentation  may  have  been 
approximately  uniform  for  long  distances. 

It  is  necessary,  therefore,  not  only  to  use  the  fossils  as  an  aid  to 
stratigraphy  in  determining  equivalency,  but  the  fossil  evidence  must 
be  so  separated  from  inferences  drawn  from  formation  names  that  its 
real  value  in  time  discrimination  can  be  independently  estimated. 

To  make  such  separation  of  the  two  sources  of  evidence  of  time 
relations  (viz:  formations  and  faunas),  it  is  necessary  to  deal  with  the 
fauna  independently  of  its  particular  place  in  any  geological  column 
of  formations.  So  considered  the  fauna  is  an  aggregate  of  organisms 
combined  in  such  number  of  genera,  species,  and  individuals  as  to 
express  the  bionic  values  of  each  in  their  relations  to  the  total  corpo- 
rate fauna  of  each  epoch  of  time  for  the  area  covered. 

The  presence  of  a  few  species  which  are  common  in  the  tj^pical 
series  of  rocks  called  the  Hamilton  formation  (as  currently  defined  by 
geologists)  is  not  evidence  of  contemporaneity  of  formation  for  the 
rocks  containing  them  in  some  other  region.  In  fact,  we  have  shown 
that  the  12  most  dominant  and  characteristic  species  of  the  formation 
actually  do  all  occur  in  the  Ithaca  formation,  which,  at  Ithaca,  is 
separated  from  the  Hamilton  formation  by  two  well-defined  geological 
formations  (the  Tully  limestone  and  the  Genesee  shale)  and  by  still 
another  series  of  rocks  with  a  distinct  fauna  (the  "lower  Portage" 
so-called,  with  the  Spirifer  lmvis  fauna) — in  all  about  400  feet 
of  strata.  Nor  does  the  mingling  of  species  of  one  fauna  with  those 
of  another  invalidate  the  value  of  the  faunas  as  time  indicators. 

Again,  in  order  to  use  the  fauna  as  a  time  indicator,  the  changes  in 
the  fauna  coincident  with  passage  of  time  must  be  observed  and  noted. 
The  study  of  the  details  of  these  Devonian  faunas,  as  has  been  already 
stated,  brought  out  the  fact  that  a  fauna  may  retain  for  a  consider- 
able thickness  of  sediments  its  integrity  as  a  general  fauna— viz, 
its  corporate  integrity.  Illustrations  are  given  in  Grabau's  and 
Cleland's  analyses  of  the  successive  faunules  of  the  Hamilton  for- 
mation.     In   such   range  of  a  fauna  through  hundreds  of  feet  of 


102  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

sediments  the  corporate  integrity  of  the  fauna  is  ascertained  by 
observing  the  continuance  of  dominance  of  the  dominant  species. 

It  was  found  that  at  an}^  particular  stage  of  the  fauna  certain  species 
were  dominant,  as  indicated  by  their  abundance  in  the  particular 
faunule.  The  relative  abundance  of  the  species  gave  a  means  of 
estimating  the  particular  adjustment  of  the  species  to  one  another 
at  the  particular  time  and  in  the  particular  environment  of  the 
faunule.  The  temporal  equilibrium  was  not  found  to  be  preserved 
for  much  thickness  of  strata,  nor,  when  studied  geographically,  for 
much  distance  of  distribution;  such  a  faunule  with  its  exact  combi- 
nation and  proportion  is  both  temporary  and  local,  and  constitutes 
the  type  of  a  single  faunal  unit — i.  e.,  a  monobion,  and  its  time  limit 
is  1  lie  hemera. 

Slight  change  of  conditions,  not  sufficient  to  effect  permanent 
change  in  the  specific  characters  of  the  species,  either  coincident  with 
passage  of  time  or  with  change  of  position,  may  disturb  the  equilib- 
rium, and  the  effect  of  the  change  is  exhibited  primarily  in  the  differ- 
ent relations  of  abundance  or  rarity  of  the  constituent  species. 

The  difference  in  these  respects  observed  upon  comparing  the  suc- 
cessive faunules  is  found  to  consist  in  a  change  in  their  relative 
dominance  as  constituent  species,  and  rarely  in  the  entire  absence  of 
any  of  the  more  common  species,  when  imperfection  of  the  collection 
is  fairly  taken  into  account.  Certainly  the  fads  indicate  that  there 
was  no  extinction  of  the  species,  for  they  came  in  again  at  successive 
places  higher  up  in  the  column  of  strata. 

To  ascertain,  then,  the  real  character  of  the  fauna  as  a  corporate 
whole,  in  terms  of  species,  it  is  necessary  to  ascertain  what  species 
are  sufficiently  dominant  to  overcome  the  lesser  changes  of  conditions, 
and  to  hold  their  preeminence,  continuously,  coincident  with  succes- 
sion of  faunules  as  recorded  in  the  geological  column  of  a  single  sec- 
tion, and  coincident  with  changes  of  conditions  as  indicated  by  the 
faunules  taken  from  separate  geographical  localities. 

The  species  Avhich  appear  most  frequently  in  sample  faunules,  rep- 
resenting geological  succession  and  geographical  distribution,  may 
hence  be  regarded  as  the  most  characteristic  representatives  of  the 
fauna  for  the  total  period  of  time  during  which  it  has  preserved  its 
faunal  integrity  and  over  the  region  in  which  it  was  normally 
adjusted  to  live.  The  presence  of  any  large  number  of  such  domi- 
nant species  of  a  fauna  may  be  safely  regarded  as  indicative  of  the 
epoch  in  which  the  fauna  was  dominant,  and  which  may  be  appro- 
priately designated  as  the  epoch  of  that  fauna. 

This  would  be  a  reasonable  conclusion  even  in  case  species  of  a 
fauna  which  in  general  succeeds  it  were  present  and  associated  with 
it  in  force.  The  argument  for  this  conclusion  is  that  the  fauna  can 
not  be  regarded  as  having  ceased  its  existence  as  a  fauna,  so  long 
as  in  a  single  faunule,  anywhere,  the  species  which  have  all  along 


wti.ltams]  SHIFTING    OF    FAUNAS.  103 

proved  their  dominance  in  the  fauna  are  not  replaced  bj'  other 
species. 

Upon  reading  on  this  basis  the  time  value  of  the  Leiorhynchus 
globuliforme  faunule  of  Chenango  County,  we  are  able  to  say,  from 
the  study  of  the  faunas,  that  the  dominance  of  the  Tropidoleptus 
fauna  is  already  passed,  although  27  of  its  species  are  present.  The 
epoch  of  the  Productella  speciosa  fauna  of  the  Ithaca  formation  is 
also  far  advanced,  but  the  Spirifer  disjunctus  stage  has  not  been 
reached  in  force,  as  only  a  slight  representation  of  its  species  is  seen. 
The  dominant  species  are  those  of  the  Productella  speciosa  fauna  of 
the  Ithaca  formation. 

So  long  as  the  majority  of  the  species,  including  a  majority  of  the 
dominant  species,  belong  to  the  faunas  characteristic  of  the  Hamilton 
and  Ithaca  formations,  the  evidence  is  strong  for  its  contemporaneity 
with  some  part  of  the  Portage  formation  of  the  Genesee  River  section. 

The  mingling  of  species  of  two  adjacent  faunas  by  slight  and 
repeated  sh  if  tings  is  well  illustrated  in  a  paper  by  Dr.  J.  M.  Clarke.0 
He  has  shown  how  the  species  of  the  "Portage  (Ithaca)  fauna"  are 
mingled  with  the  species  of  the  "Portage  (Naples)  fauna,"  as  he  calls 
them,  in  central  New  York.6  In  this  paper  is  brought  out  the  evi- 
dence of  the  great  difference  in  composition  between  the  fauna  of 
western  New  York  in  the  Portage  rocks  and  the  faunas  occupying  the 
same  horizon  in  central  New  York.  The  method  of  accounting  for 
the  presence  of  both  faunas  in  the  same  section  is  that  advocated  in 
this  paper.  Dr.  Clarke  speaks  of  the  fauna  of  the  western  extension 
of  the  Portage  group  as  an  "exotic  fauna,"  and  describes  the  faunas 
of  the  central  and  eastern  sections  as  "indigenous."  Confirmation  of 
the  interpretation  given  in  the  present  discussion  appears  in  the  state- 
ment that  the  Ithaca  group  fauna  is  a  modified  Hamilton  fauna,  with 
the  following :  "It  contains  a  more  abundant  representation  of  unmod- 
ified Hamilton  species  in  the  meridional  section  along  the  Chenango 
River."  If  we  had  passed  the  time  in  which  the  "Hamilton,"  i.  e., 
Tropidoleptus  carinatus,  fauna  was  living  in  its  integrity  the  species 
would  show  modification.  The  greater  abundance  of  these  "  unmodi- 
fied "  species  in  the  eastern  outcrops  points  to  the  metropolis  of  this 
fauna,  in  which  the  fauna  itself  has  maintained  its  bionic  integrity. 
Although  outside,  only  a  hundred  miles  westward,  a  new  fauna,  exotic 
in  origin,  has  occupied  this  ground  with  partial  replacement  there  of 
the  indigenous  species  of  the  region. 

PRINCIPLES    INVOLVED    IN    SHIFTING    OF    GEOLOGICAL    FAUNAS. 

This  brings  us  to  a  consideration  of  the  fundamental  principles 
involved  in  the  shifting  of  faunas,  announced  in  1883,  the  outlines  of 
which  were  further  set  forth  in  1892  in  the  vice-presidential  address 


"The  stratigraphic  and  faunal  relations  of  the  Oneonta  sandstones  and  shales,  tin-  [thaca  and 
the  Portage  groups  in  central  New  York:  Fifteenth  Ann.  Rept.  State  Geologist  New  Fork, 
189?,  pp.  81-81. 

''Ibid.;  see  p.  53,  etc.,  for  the  lists,  and  fi^r.  .">.  i>  51,  for  the  diagram. 


104  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

before  Section  E  of  the  American  Association  for  the  Advancement  of 
Science. 

In  a  paper  read  before  the  American  Association  in  August,  1885, 
the  fact  of  shifting  of  faunas  was  illustrated  by  a  chart  based -on  the 
detailed  examination  of  the  faunules  of  ten  sections  cutting  across 
the  strata  of  the  Devonian,  extending  from  Cuyahoga  County,  Ohio, 
eastward  to  Unadilla,  in  Otsego  County,  New  York.  A  brief  report 
of  the  paper  was  published  in  the  proceedings,  and  the  formulated 
expression  of  the  law  was  given  in  the  following  words: 

The  actual  order  of  faunas  met  with  in  a  vertical  section  is  not  necessarily 
expressive  of  biologic  sequence,  but  signifies  the  sequence  of  the  occupants  of  that 
particular  area. 

The  change  in  the  species. from  one  stratum  to  the  next  may  express  the  shift- 
ing for  miles  of  the  actual  inhabitants,  and  if  the  change,  within  a  few  feet  of 
strata,  is  to  an  entirely  distinct  group  of  species,  the  evidence  should  be  taken  as 
pointing  to  a  considerable  shifting  of  conditions  of  the  bottom.  If  in  such  case 
each  fauna  is  kept  distinct,  the  means  of  tracing  the  geographic  distribution  and 
modification  are  at  hand.  If  mingled,  then  the  collection,  though  made  at  the 
same  locality,  will  only  confuse.  Two  such  faunas  meet  at  Owego,  Tioga  County, 
in  distinct  strata,  but  in  rocks  which  are  of  similar  lithologic  character;  one  is  a 
remnant  of  a  prevailing  western  fauna,  the  other  is  an  eastern  and  late  stage  of  a 
new  fauna. 

It  was  there  shown  how,  by  the  shifting  of  faunas  and  formations, 
the  lower  part  of  the  Catskill  formation  of  the  Hudson  River  section 
was  actually  equivalent  to  the  Oneonta  formation  of  the  Delaware 
County  section,  1<>  the  Ithaca  formation  of  the  Cayuga  Lake  section, 
and  to  the  Portage  formation  of  the  Genesee  River  section. 

From  the  established  lad  that  the  Catskill  (a  formation  discrimi- 
nated on  a  lithological  basis)  did  not  occupy  the  same  horizon,  when 
the  horizons  were  determined  on  a  paleontological  basis  in  sections 
not  over  50  miles  apart,  it  was  argued  that  there  is  need  of  differ- 
entiating by  nomenclature  the  vertical  divisions  discriminated  by 
fossils  from  the  lithological  divisions  called  formations. 

The  same  subject  was  further  elaborated  in  a  discussion  before  the 
Geological  Society  at  Boston  in  1893,  the  immediate  topic  then  under 
examination  being  the  place  of  the  Catskill  formation  in  the  geological 
time  scale.  In  that  discussion  I  proposed  the  use  of  dual  nomencla- 
ture in  geological  classification,  and  again  showed  how  the  shifting 
of  faunas  from  place  to  place  necessitates  their  appearance  at  different 
horizons  in  separate  sections,  using  horizon  in  the  sense  of  synchrony 
in  time.  By  this  interpretation  of  the  facts  the  Catskill  formation 
was  shown  to  occupy  in  eastern  New  York  the  actual  horizon  of  the 
Oneonta  of  Delaware  County,  of  the  Ithaca  formation  of  the  Cayuga 
Lake  section,  and  of  the  Portage  of  the  Genesee  River  section. 

The  lack  of  statistics  for  the  discussion  of  migration  of  faunas  was 
greatly  felt  in  all  those  early  studies  of  the  subject. 

The  deep  interest  taken  in  the  question  by  numerous  investigators 
has  been  shown  by  the  many  papers  which  have  been  published  since 


Williams.]  SHIFTING    OF    FAUNAS.  105 

then,  giving  the  much  needed  statistics.  With  these  statistics  in 
hand  it  is  possible  now  to  express  more  clearly  the  laws  involved  in 
this  shifting  of  the  corporate  faunas,  as  wholes,  and  their  coincident 
modification. 

BIOLOGICAL  CONSEQUENCES  OF  SHIFTING  OF  FAUNAS. 

The  principles  assumed  to  account  for  the  change  in  the  character 
of  faunas  are  of  two  kinds,  viz.,  (i)  the  geographical  shifting  of  the 
faunas,  and  (ii)  the  evolution  of  organisms  independent  of  change  of 
environment.  Only  so  long  as  the  conditions  of  a  marine  basin 
remain  constant,  or  differ  so  slightly  and  so  slowly  that  the  faunas 
living  under  them  can  preserve  their  integrity  as  a  whole  and  pre- 
serve that  balance  of  adjustment  to  each  other  which  may  be  called 
biological  equilibrium — only  so  long  as  these  conditions  remain  can 
the  fauna  be  supposed  to  retain  its  integrity  as  a  fauna.  This  state 
of  things  is  represented  in  many  geological  formations  for  a  great 
period  of  time.  Throughout  strata  of  limestone,  in  some  places 
reaching  1,000  feet  or  more  in  thickness,  this  integrity  of  the  fauna  is 
preserved.  It  is  to  be  interpreted  as  due  in  some  measure  to  the 
conditions  of  environment  remaining  constant,  whether  evolution 
takes  place  under  such  conditions  or  not.  Attention  is  called  in  the 
present  statement  to  the  fact  that  the  fauna  as  a  whole  does  maintain 
a  relative  integrity,  which  permits  the  assumption  of  at  least  very 
slight  evolution  of  the  types.  Some  of  the  species  may  drop  out,  and 
occasionally  a  few  new  ones  ma}f  come  in  during  the  course  of  Hi  is 
life  period — if  we  might  so  call  it — of  the  fauna.  At  the  same  time  the 
variations,  pure  and  simple,  which  are  observed  are  very  slight,  and 
not  to  be  compared  with  the  differences  which  are  often  noted  on 
passing  across  a  very  limited  distance  of  sediments  where  the  con- 
ditions have  changed  and  the  fauna  is  broken  up.  It  is  nol  necessary 
to  assume  that  a  very  great  length  of  time  has  intervened  between  the 
embedding  of  the  old  and  the  appearance  of  the  new  fauna  as  we 
follow  upward  a  strati  graphical  section.  Throughout  the  geological 
column  many  cases  are  known  where  one  fauna  is  i  in  mediately  fol- 
lowed by  another,  without  greater  break  of  sedimentation  than  the 
passage  between  two  strata  and  with  perfect  parallelism  of  the  con- 
tiguous strata,  yet  the  species  are  almost  completely  changed.  The 
species  of  the  same  genera  are  often  found  to  be  quite  different. 

The  student  of  paleontology  is  not  required  to  assume  that  in  such 
cases  the  second  fauna  has  been  evolved  directly  Prom  the  species 
which  underlie  it  in  the  strata  below.  The  more  natural  assumption, 
and  the  one  which  is  borne  out  by  further  investigations  in  other 
regions,  is  that  the  new  fauna  has  come  to  be  deposited  in  the  second 
series  of  beds  lying  above  the  first  fauna  by  the  shift  ingot'  the  faunas 
upon  the  ocean  bottom  itself.  A  migration  from  some  other  region 
into  the  region  where   it   is  recorded   is   made   by  the  species.     This 


106  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

proposition  requires  us  to  assume  that  our  second  fauna  lived  con- 
temporaneously with  the  one  immediately  underlying  it,  but  in  some 
other  region  separate  from  the  one  in  which  it  is  recorded  Examples 
of  such  shifting  of  faunas  have  occasionally  been  met  with  in  the 
investigations  of  deep  seas.  Professor  Verrill/  in  his  studies  of  the 
faunas  of  the  Atlantic  edge  of  the  New  England  shores,  has  pointed 
out  a  remarkable  case  of  this  kind.  About  80  miles  off  Woods  Hole 
one  season  a  unique  fauna  appeared — the  tile-fish  fauna — with  a  new 
and  abundant  set  of  species,  a  great  proportion  of  them  new  and 
representing  altogether  a  new  fauna.  This  fauna  afterwards  was 
lost  sight  of,  and  the  dredgers  found  no  traces  of  it  in  the  region 
where  it  was  first  found.  The  explanation  of  the  sudden  appear- 
ance of  such  a  fauna  is  that  the  shifting  of  currents,  or  some  other 
movements  of  conditions  in  the  ocean,  led  to  the  temporary  migration 
of  the  fauna  over  the  banks  it  occupied,  and  to  its  later  retreat  and 
resumption  of  its  old  conditions. 

The  tile-fish  fauna  may  belong  to  the  deeper  seas  under  the  Gulf 
Stream,  or  it  may  be  connected  with  other  currents  that  at  present 
we  are  unfamiliar  with.  However,  this  immigration  may  be  taken  as 
an  example  of  what  has  unmistakably  taken  place  over  and  over 
again  in  the  sea  basins  whose  life  records  are  preserved  in  the  fossils 
of  our  stratified  rocks.  Of  course  the  modification  of  species  in 
the  course  of  time  would  affect  such  species  as  lived  in  a  continuous 
series  of  reproductions  for  millions  of  years;  such  modifications, 
however,  might  be  spoken  of  as  purely  evolutional.  Paleontology 
gives  us  evidence  of  such  modifications  of  a  general  kind  in  the 
character  of  the  species  of  a  genus  coincident  with  the  passage  of 
time;  i.  e.,  a  young  stage,  a  vigorous  middle  stage  of  the  life  history, 
and  a  final  decadent  stage  of  the  life  of  the  genus.  Facts  of  this 
kind  may  be  gathered  from  the  study  of  faunas  which  have  preserved 
their  integrity  through  a  great  thickness  of  sediments  in  a  single 
basin;  but  the  conditions  more  important  to  the  paleontologist,  and 
more  necessary  to  be  observed  in  making  correlations,  are  those 
directly  coincident  with  the  movement  of  faunas  from  place  to  place; 
i.  e.,  the  shifting  of  faunas.  This  shifting  of  faunas  is  well  illus- 
trated in  the  history  of  the  latter  part  of  the  Paleozoic  formations  in 
the  central  basin  of  North  America.  The  general  proposition  assumed 
to  explain  such  shifting  of  the  geographical  position  of  faunas  and 
their  containing  formations,  as  we  follow  them  successively  through 
a  geological  section,  is  as  follows : 

It  is  assumed,  first,  that  the  evolutional  process  of  change  is  geolog- 
ically very  slow  in  its  effects;  that  so  long  as  the  same  conditions  pre- 
vail with  sufficient  exactness  to  prevent  the  disturbance  of  the  biolog- 
ical equilibrium  of  a  fauna,  so  long  the  individual  species  will  retain 
their  distinctive  characters  and  relative  abundance  in  a  general  fauna. 


«Aru.  Jour.  Sci.,  3d  series,  Vol.  XXIV,  p.  3(«5. 


wili.tams]  SHIFTING    OF    FAUNAS.  107 

On  the  other  hand,  it  is  assumed  that  changes  of  conditions  of  environ- 
ment, which  may  have  been  very  slight  but  which  necessitate  a  shift- 
ing or  migration  of  the  faunas,  may  produce  some  and  even  consider- 
able changes  in  a  short  time  in  the  faunas  concerned.  The  changes 
may  be  produced  in  the  following  ways:  If  the  forced  migration  be 
sudden,  the  ability  of  the  different  species  to  migrate  will,  in  the  first 
place,  be  very  unequal;  some  species  can  migrate  and.  some  can  not; 
some  can  migrate  easily  and  others  with  difficulty,  and  the  sudden 
necessity  of  migrating,  as  a  fauna,  must  necessarily  break  up  what  I 
have  called  the  biological  equilibrium  of  the  fauna.  In  every  shifl 
some  species  will  be  forced  to  drop  out,  because  they  can  not  migrate  or 
because  they  can  not  adjust  themselves  to  the  new  conditions.  1 1*  such 
a  dropping  out  of  species  from  the  faunas  takes  place,  there  results  at 
once  a  new  condition  of  affairs  in  the  faunal  life.  Competition  is  dif- 
ferent; the  means  of  livelihood  have  changed;  the  necessity  of  new 
habits  of  life  is  forced  upon  the  remaining  species.  In  the  process  of 
adjustment  of  one  to  another,  irrespective  of  the  changing  conditions, 
we  may  suppose  that  the  species  which  remain  in  the  fauna  will,  some 
of  them,  be  reduced  in  rank  and  some  of  them  increased,  which  will 
be  indicated  by  change  in  abundance  or  rarity.  The  increased  or 
decreased  abundance  of  species  in  the  fauna  is  one  of  the  evidences 
of  this  shifting  process.  Where  a  species  is  abundant,  I  have  fre- 
quently observed  that  variability  also  is  increased. 

Relatively  speaking,  the  variability  is  almost  in  proportion  to  1  lie 
vigor  and  abundance  of  reproduction  of  the  individuals.  Here  at 
once  we  see  a  means  of  rapid  evolution.  If  a  species  varies  and  the 
variation  is  augmented  by  favorable  conditions  of  livelihood,  the 
change  from  one  environment  to  another  necessitates  1  he  modifical  ion 
of  some  of  the  species  almost  immediately,  and  the  variability  of  the 
fauna  will  be  strongly  expressed  when  migration  of  the  species  lakes 
place.  The  adjustment  of  the  fauna  to  its  changed  conditions  is  a 
matter  of  slower  accomplishment,  but  it  maybe  supposed  that  migra- 
tion from  one  region  to  another  will  result  in  more  or  less  modifica- 
tion and  readjustment  of  the  proportionate  fertility  and  abundance  of 
the  species,  unless  the  change  of  environmental  conditions  be  so  slow- 
as  to  enable  the  whole  fauna  to  move  its  center  of  distribution  with- 
out disturbance  of  its  bionic  equilibrium.  Such  cases  would  be  rare 
and  the  distances  not  great. 

The  investigations  of  Grabau  and  Cleland,  already  referred  to,  illus- 
trate this  principle.  The  study  of  the  Cayuga  Lake  section  was  made 
for  the  purpose  of  furnishing  a  minute  comparison  with  the  Eighteen- 
mile  Creek  section,  as  well  as  to  determine  the  exact  composition  of 
the  temporary  combination  of  specie's  found  in  each  stratum.  'Hie 
result  was  very  clear.  The  general  fauna  was  found  to  he  very  much 
alike  from  the  bottom  of  the  Hamilton  up  to  its  lop  in  both  sections. 
The  difference  between  the  several  zones  was  constantly  fluctuating, 


108  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

and  the  fluctuations  are  not  expressed  so  much  by  an  incursion  of 
new  species  or  a  disappearance  of  some  of  the  old  species  entirely, 
from  the  fauna,  but  the  differences  between  the  temporary  faunules 
of  each  successive  zone  are  found  to  consist  chiefly  in  relative  abun- 
dance of  specimens  and  in  relative  size  of  those  which  do  appear  in 
the  faunules. 

Other  cases  have  been  investigated,  and  from  their  study  I  conclude 
that  the  ordinary  changes  which  take  place  in  the  life  inhabitants  of 
the  seas  on  passing  from  one  stratum  to  the  next  are  chiefly  differ- 
ences in  abundance  and  vigor  of  the  several  species.  When  it  is 
found,  on  passing  from  one  zone  in  a  section  upward  to  the  next,  that 
the  genera  change  with  each  new  set  of  species  the  inference  is  at 
once  that  the  change  is  due  to  migration.  When,  therefore,  accord- 
ing to  the  above  interpretation,  it  is  observed  that  the  faunas  occu- 
pying the  formations  of  the  geological  scale  are  not  the  same  in  two 
neighboring  regions,  the  interpretation  may  be  one  of  two:  Either  we 
have  a  succession  of  several  faunas  which  may  be  contemporaneous, 
but  represent  different  conditions  of  environment  at  the  same  time, 
or  we  have  the  modification  of  a  single  fauna  into  numerous  local 
faunules — local  and  temporary — as  it  has  been  forced  to  migrate. 
Interpreting  Paleozoic  history  on  this  basis,  it  becomes  necessary  to 
assume  that  the  faunas  must  be  distinguished  geographically  as  well 
as  vertically. 

EFFECT  OF  SHIFTING    OF    FAUNAS   ON   CLASSIFICATION   OF  GEO- 
LOGICAL FORMATIONS. 

If  we  trace  the  sediments  of  the  Devonian  for  several  hundred  miles 
in  one  direction,  from  the  west  in  Ohio  eastward  across  the  States  of 
New  York  and  Pennsylvania  to  their  eastern  limits,  a  remarkable 
series  of  changes  is  observed  in  the  character  of  the  sediments  as  a 
whole,  which  is  interpretable  by  this  study  of  the  faunas  contained  in 
them.  The  facts  developed  by  the  minute  analysis  of  the  Devonian 
faunas  already  presented  show  that  formational  equivalency  is  not  in 
accordance  with  faunal  equivalency  for  the  different  parts  of  the  region 
examined.  In  other  words,  if  we  attempt  to  trace  a  common  geolog- 
ical horizon  across  the  country  by  means  of  the  evidence  of  forma- 
tional uniformity,  we  will  reach  a  different  conclusion  as  to  equivalent 
formations  than  if  the  means  of  determination  be  the  evidence  of 
faunal  integrity. 

This  fact  may  be  expressed  in  the  case  of  the  Catskill  sedimenta- 
tion by  saying  that  the  Catskill  formation  occupies  a  lower  place  in 
the  geological  column  in  eastern  New  York  and  Pennsylvania  than  it 
does  a  hundred  miles  to  the  northwest.  In  this  statement  higher  and 
lower  are  terms  the  estimation  of  which  is  based  upon  evidence  of 
place  of  marine  faunas  in  the  rocks. 

The  case  of  the  Oneonta  sandstone  and  its  place  in  the  midst  of  the 
faunas,  described  in  detail  on  previous  pages  of  this  report,  is  another 


wim.iams.]  SHIFTING    OF    FAUNAS.  109 

vivid  illustration  of  the  fact.  As  a  formation  the  Oneonta  is  a  well- 
defined  body  of  rock  in  Otsego  County,  New  York,  occupying  a  defi- 
nite place  in  the  geological  column  of  the  Devonian. 

The  evidence  we  have  been  examining,  however,  leads  to  the  belief 
that  the  particular  part  of  the  geological  column  which  was  being 
formed  in  eastern  Ohio  at  the  time  of  the  deposition  of  the  Oneonta 
formation  in  eastern  New  York  is  not  a  sandstone  but  a  soft  sand 
shale  called  the  Ohio  shale.  If  we  follow  these  Ohio  shales  eastward 
we  find  that  they  become  coarser,  and  when  we  reach  the  Genesee 
Valley  the  sediments  are  still  fine  shales  with  some  sandstones,  laid 
down  in  even-bedded,  sometimes  flaggy,  layers,  with. few  fossils,  and 
the  fossils  belong  to  a  fauna  quite  different  from  that  of  either  the 
Hamilton  below  or  the  Chemung  above.  The  rocks  here  are  known  as 
the  Portage  formation.  Following  the  rocks  occupying  the  same  geo- 
logical horizon  still  eastward,  by  the  time  we  reach  the  meridian  of 
Cayuga  Lake  and  Ithaca  the  same  part  of  the  column  is  represented 
by  argillaceous  and  sandy  shales  alternating  for  several  hundred  feet. 
Many  of  the  layers  are  rich  in  fossils  and  contain  species  of  both  the 
lower  Hamilton  and  the  higher  Chemung  formations,  together  with 
certain  peculiar  and  characteristic  species  which  have  come  in  from 
elsewhere  or  have  been  evolved  from  the  faunas  prevailing  at  the 
lower  horizons.  In  the  midst  of  these  sediments  there  are  beds  of 
flagstones  and,  locally,  of  massive  sandstones.  In  this  region  the 
rocks  are  known  as  the  Ithaca  group  or  formation.  Following  the 
sections  still  eastward  as  far  as  Chenango  Valley,  the  flagstone  quar- 
ries of  Norwich,  Oxford,  and  Greene  townships  are  found  occupying 
the  place  of  the  more  fossiliferous  Ithaca  zones  farther  west. 

Still  farther  east,  the  Oneonta  sandstones,  including  red  sandstones 
and  even  conglomerates,  with  fish  remains  and  some  plants,  but  hold- 
ing very  slight  traces  of  any  marine  fauna,  occur  in  considerable 
thickness.  From  the  evidence  at  present  in  sight  I  conclude  that  this 
series  of  sandstones  is  continued  eastward  without  interruption  and 
is  probably  a  portion  only  of  what  is  called  the  Catskill  formation  of 
the  Catskill  mountain  region.  Theoretically  this  is  assumed  to  be 
the  fact. 

If  now  we  analyze  the  distribution  of  these  sediments,  which  are 
supposed  to  have  been  laid  down  during  the  same  epoch  of  time,  we 
find  that  four  distinguishable  classes  of  sediments  may  be  recognized 
as  in  process  of  deposit  at  different  areas  of  the  bottom  at  the  same 
time.  These  may  be  spoken  of  as  (a)  the  black  shale,  (b)  the  rela- 
tively barren  Portage  shale,  (c)  the  fossiliferous  argillaceous  shales, 
and  (d)  the  red  sandstones. 

BLACK   SHALE   SEDIMENTS. 

The  Ohio  shales  are  a  continuation  upward  of  what  is  called  the 
black  Genesee  shale  in  other  regions,  and  consist  of  a  series  of  fine- 
grained somewhat  arenaceous  sediments  which  have  the  peculiarity 


110  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

of  being  made  up  of  very  thin  and  even  laminae  and  are  very  uniform 
for  a  thickness  of  several  hundred  feet.  Where  they  are  found  in 
the  black  stage,  this  uniformity  in  the  size  of  the  grains,  the  evenness 
of  the  surfaces  of  lamination,  and  the  uniformity  of  the  sediments 
from  top  to  bottom  are  striking  characteristics.  Faunally  they  are 
distinguished  by  a  marine  fauna  containing  a  few,  generally  minute, 
invertebrates,  many  traces  of  plants,  and  often  the  spore  cases  of 
rhizocarps,  together  with  the  bones  of  large  fish,  distributed  irregu- 
larly among  the  sediments.  These  peculiarities  indicate  quiet  condi- 
tions of  sedimentation — conditions  not  enough  disturbed  by  currents 
or  even  wave  action  to  affect  the  smoothness  of  the  sediments  on  the 
bottom — and  show  that  the  sources  of  the  sediments  were  at  a  con- 
siderable distance.  The  indications  also  point  strongly  to  some  kind 
of  Sargasso  sea,  as  suggested  by  Newberry;  and  it  is  possible  that 
this  coating  of  the  surface  of  the  sea  by  a  living  vegetation  may 
account  both  for  the  black  character  of  the  sediments  and  for  the 
absence  of  any  considerable  marine  population. 

PORTAGE    FORMATION   SEDIMENTS. 

The  second  group  of  sediments  still  shows  a  sparsity  of  invertebrate 
life,  but  exhibits  alternations  of  sediments  ranging  from  the  fine, 
evenly  laminated  layers  of  the  black  shale  to  the  coarser  arenaceous 
shales  ami  sandstones,  with  occasional  indications  of  shore  action  in 
the  form  of  ripple  marks,  worm  tracks,  and  pebbles.  This  set  of 
sediments  is  well  represented  in  the  typical  Portage  formation  of 
west-central  New  York. 

FOSSILIFEROUS   SHALY   SEDIMENTS   OF   ITHACA   GROUP. 

A  third  class  of  sediments  is  found  to  be  typical  of  the  sections 
south  of  Cayuga  Lake,  in  the  formations  described  by  me,a  whose 
fauna  is  more  fully  elaborated  in  Mr.  Kindle's  paper  on  The  Faunas 
of  the  Ithaca  Group.  These  are  composed  of  alternating  sediments 
of  sands  and  shales,  richly  fossiliferous,  much  more  roughly  deposited, 
and  rarely  showing  the  peculiar,  evenly  laminated  character  of  the 
typical  Genesee  seen  in  the  lighter-colored  shales  of  the  Portage  of 
the  Genesee  Valley,  and  in  the  Erie  shale  of  Ohio. 

RED    SANDSTONE   SEDIMENTS. 

The  fourth  set  of  sediments  is  found  in  the  East,  and  is  represented 
by  the  Oneonta  sandstones  and  the  flagstones — purple  and  red — which 
reach  as  far  west  as  the  Chenango  Valley,  and  traces  of  which 
appear  in  the  midst  of  the  Ithaca  group  of  the  Cayuga  Lake  meridian. 
These  more  eastern  sediments  are  generally  tinged  with  red.  They 
are  often  coarse-grained  with  interspersed  pebbles,  and  sometimes 

a  Bulletin  U.  S.  Geol.  Survey  No.  3. 


Williams.]  SHIFTING    OF    FAUNAS.  Ill 

have  layers  of  clearly  defined  conglomerate.  They  rarely  contain 
any  purely  marine  life,  except  lingulas.  The  organisms  they  do 
contain  are  generally  fish  and  a  few  large  lamellibranchs  (Amnigenia) 
which  possibly  were  fresh- water  mollusks,  and  may  have  occupied  a 
place  similar  to  the  unios  of  the  present  time.  Plant  remains  of 
unmistakable  land  origin  are  frequently  found  in  the  sediments. 

Thus  in  this  fourth  class  of  sediments  the  indications  of  nearness 
of  shore  are  very  clear,  not  only  in  the  nature  of  the  sediments  them- 
selves, but  in  the  organic  remains  buried  in  them.  Bearing  in  mind 
this  fourfold  classification  of  the  sediments,  geographically  arranged, 
it  may  be  assumed  that  the  relationship  they  bear  to. each  other  is  in 
general  coincident  with  distance  from  a  shore  outside  of  which  they 
were  laid  down.  The  fourth  represents  the  deposits  nearest  the  shore; 
the  third  the  zone  of  littoral  sediments,  rich  in  organic  marine  life. 
Going  still  farther  outward  from  the  shore  line  the  more  or  less  bar- 
ren sedimentation  is  found  beyond  the  zone  of  the  littoral  fossils,  but 
still  near  enough  to  the  surface  to  be  influenced  by  wave  action  and 
by  local  and  temporary  disturbance  of  the  currents  and  supply  of 
sediments;  still  beyond  this  are  the  sediments  of  the  first  class,  above 
enumerated,  which  are  beyond  the  reach  of  movements  of  currents, 
or  oscillation  of  supply  and  distribution  of  the  sediments  derived 
from  the  shore. 

We  have  here,  then,  a  set  of  formations  which  are  associated  with 
different  faunal  populations,  and,  although  they  may  be  supposed  to 
be  synchronously  deposited,  the  several  formations,  discriminated  for 
particular  regions  where  each  one  is  typically  expressed,  possess 
almost  nothing  in  common.  The  stratigraphical,  the  lithological,  and 
the  paleontological  characters  are  distinct  for  each  one  of  the  four 
classes  of  formations. 

The  relation  which  these  four  classes  of  sediments  bear  to  one 
another,  and  the  way  in  which  they  stand  related  in  the  stratigraphical 
succession  of  a  single  section,  lead  one  to  the  hypothesis  that  they 
represent  approximately  relative  distances  from  the  original  shore  line. 
With  this  as  a  working  hypothesis,  it  is  evident  that  a  shifting 
which  might  be  observed  in  one  of  the  zones  of  sedimentation  should 
be  recognized  by  a  corresponding  shifting,  in  the  same  direction,  of 
the  other  zones  of  sediments. 

When  it  is  observed  that  the  Tropidoleptus  fauna  slops  in  the  sec- 
tions of  western  New  York  with  the  deposit  of  the  Genesee  shale, 
while  in  eastern  New  York  the  dominant  species  of  the  fauna  con- 
tinue on  for  several  hundred  feet  of  strata  above  the  horizon  of  the 
Genesee  shale,  the  inference  is  justified  that  not  only  has  the  Tropi- 
doleptus fauna  shifted  eastward,  but  that  the  Genesee  shale  of  the 
western  New  York  section  shifted  eastward  to  cut  it  off,  and  that  a 
place  may  be  evident  in  the  eastern  extension  of  the  Genesee  sedi- 
mentation   corresponding   to  the   Portage    phase    of   sedimentation. 


112  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

This  phase  may  be  recognized  in  the  Sherburne  formation  of  Che- 
nango County.05  In  the  same  way  the  Portage  of  western  New  York 
should,  on  this  hypothesis,  be  represented  by  a  black  shale  laid  down 
farther  west,  such  as  the  Ohio  shale,  and  to  the  east  it  actually  blends 
into  the  Ithaca  and  then  into  the  Oneonta,  in  accordance  with  the 
theory.  Still  higher  in  the  series  the  Catskill  formation  of  the  east- 
ern part  of  New  York  is  at  the  same  horizon  as  the  fossiliferous 
Chemung  of  the  central  part  of  the  State  and  the  Erie  shale  of  the 
sections  of  western  Pennsylvania  and  Ohio. 

Thus  the  shifting  of  faunas  furnishes  a  key  by  which  the  chrono- 
logical relations  of  the  formations  which  hold  the  fossils  may  be  deter- 
mined with  a  degree  of  accuracy  not  possible  on  any  other  basis,  and 
reduces  to  order  facts  which  on  the  ordinary  interpretation  are  not 
only  without  apparent  order  but  seem,  at  least,  to  be  unrelated  to 
each  other. 

The  sequence  of  the  faunas  themselves,  in  each  section,  furnishes 
a  clue  to  the  direction  in  which  the  shifting  has  moved.  If,  for 
instance,  the  passage  upward  is  from  richly  fossiliferous  shales  into 
black,  nearly  barren,  even-bedded  shale,  the  locality  where  the  sedi- 
ments occur  was  sinking,  and  the  shore  line  was  becoming  more  dis- 
tant; and,  on  the  assumption  that  at  the  time  the  general  shore  lines 
were  to  the  east  and  north  of  central  New  York,  the  inference  is  that 
the  pushing  in  of  the  black  Genesee  shale  over  the  Hamilton  was  from 
the  southwest.     All  the  facts  bear  out  this  conclusion. 

Again,  if  the  succession  of  beds  is  from  fossiliferous  shales  into 
red,  flaggy,  and  coarse  sandstones,  the  interpretation  is  that  the  region 
was  rising.  In  central  New  York  rising  would  cause  the  shore  lines  to 
encroach  upon  the  sea  advancing  toward  the  west.  This  is  the  fact 
in  the  case  of  the  Oneonta  sandstone;  and  all  the  facts  bear  out  this 
interpretation. 

FAUNAL   SHIFTING   AND   CORRELATION. 

Thus  a  minute  study  of  the  faunules  in  their  relation  to  the  sedi- 
ments and  their  distribution  and  succession  furnish  a  means  of  cor- 
relation far  better  than  continuity  of  like  sediments,  a  safe  method 
when  the  transgression  is  parallel  to  shore  lines  but  fallacious  when 
the  formation  is  traced  at  right  angles  to  the  shore  line  of  origin  of 
the  sediments.  It  is  a  surer  method  of  correlation  than  reliance  upon 
identity  of  fossils  alone,  for  we  have  ascertained  that  a  prevalent 
fauna  retains  a  general  integrity  of  its  specific  composition  for  a  time 
of  great  length,  measured  by  the  sedimentation  of  many  hundred 
feet  of  ordinary  shale  and  sandstone  rocks,  and  through  a  thickness 
of  limestones  which  may  reach  several  hundred  feet. 

The  relation  of  limestones  to  the  other  classes  of  sediments  has  not 
been  indicated  in  the  above  analysis.     It  is  more  difficult  to  determine 

a  See  section  at  "  Nigger  Hollow,11  Prosser,  p.  134,  XIX  C  2. 


Williams.]  SHIFTING    OF    FAUNAS.  113 

the  precise  relation  of  limestone  sediments  to  the  shores,  for  there  are 
no  terrigenous  materials  in  the  sediments.  The  limestone,  when  pure, 
does  not  necessarily  indicate  great  distance  from  land  erosion,  and  it 
may  not  indicate  distance  from  actual  shore. 

In  the  discussion  of  the  Cuboides  zone  and  its  fauna a  I  adopted, 
as  a  working  hypothesis,  the  view  that  limestone  sedimentation  con- 
stitutes a  fifth  class  lying  beyond  the  black  shale  end  of  the  series. 
I  think,  in  general,  this  is  borne  out  by  the  facts;  still  it  must  be 
observed  that  limestones  form  near  coasts,  and,  under  favorable 
conditions,  in  water  not  deep. 

Where  limestones  continue  to  form  for  long  periods,  during  which 
some  oscillation  is  evident,  the  associated  fragmental  material  is  fine 
grained,  and  the  passage  from  limestone  into  terrigenous  deposits  is 
generally,  if  not  always,  through  fine-grained  sediments  to  coarse; 
often  black  shales  are  among  the  transition  beds.  As  a  working 
hypothesis  it  would  appear  still  to  be  safe  to  regard  limestones  as  al 
least  in  the  same  class  with  black  shales  on  a  basis  of  relative  distance 
from  shore,  and  as  a  means  of  determining  the  direction  of  the  shift- 
ing of  the  faunas. 

This  particular  order  of  distribution  of  the  conditions  of  sedimen- 
tation in  relation  to  distance  from  shore  line  may  require  modification 
as  the  facts  are  more  thoroughly  elaborated,  but  that  the  several  con- 
temporaneous faunas  associated  with  distinct  types  of  sedimentation 
have  shifted  together  laterally  seems  to  be  established  beyond  ques- 
tion.    The  following  facts  seem  to  favor  this  view: 

(1)  Fossil  faunas  give  indication  of  their  normal  association  with 
particular  classes  of  sediments. 

Unless  we  suppose  that  the  fauna  has  shifted  its  local  habitat  the 
abrupt  termination  of  a  class  of  sediments  in  a  given  section  requires 
the  assumption  that  the  fauna  ceased  to  live,  whereas,  the  actual 
continuity  of  life  of  species  associated  in  faunal  aggregates  is  theo- 
retically an  established  fact. 

(2)  Sediments  of  each  class  are  of  limited  geographical  distribution. 
This  fact  taken  with  No.  1  makes  the  following  a   rational  conclu- 
sion, viz: 

(3)  A  fauna  in  its  purity  is  restricted  in  its  geographical  distribution . 
If  a  fauna  in  its  purity  has  a  limited  geographical  distribution,  the 

recurrence  of  the  same  fauna  in  a  continuous  section,  after  the 
occupation  of  the  region  by  an  entirely  distinct  fauna,  can  be 
explained  only  on  the  assumption  that  the  fauna  moved  away  from 
the  region  during  the  interval  of  occupation  by  the  latter. 

(4)  Such  recurrences  of  faunas  are  establish  <  I  fa  <  /*,  as  shown  on  the 
previous  pages  of  / // is  < I ist : 1 1 ss ion. 

(5)  A  formation  {when  understood   to   be   a   continuous  series  of 

"Bull.  Geol.  Soc.  Am.,  Vol.  I,  189<),  p.  481. 

Bull.  210— 03 8 


114  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull  210. 

superimposed  strata,  composed  of  the  same  class  of 'lifhological  sediments) 
may  contain  a  large  number  of  zones,  each  with  a  faunule  differing 
in  particular  from  the  others;  but  all  the  faunules  from  bottom,  to  top 
may  be  made  up  of  varying  combinations  of  a  common  list  of  species, 
i.  e. ,  the  common  fauna  of  the  formation. 

The  absence  or  presence  of  the  individual  species  in  the  separate 
zones  of  faunules  is  more  rationally  explained  on  the  assumption  of 
this  temporary  shifting  of  the  species  than  by  the  hypothesis  that 
either  the  species  temporarily  ceased  to  live  or  they  were  simply  not 
recorded  in  the  sediments.  So  long  as  the  species  continued  to  live 
there  must  have  been  some  locality  in  which  favorable  conditions 
for  their  living  were  found.  The  conclusion  is  reasonable,  therefore, 
that  they  shifted  their  place  of  habitation — in  the  case  of  faunules, 
not  far  enough  in  distance  to  disturb  the  normal  equilibrium  of 
species  in  the  general  fauna. 

This  difference  in  the  relative  abundance  of  the  component  faunules 
of  a  continuous  fauna  leads  to  the  conclusion  that  we  are  dealing  with 
parts  of  the  fauna  at  varying  distances  from  its  center,  or  metropolis, 
rather  than  with  fluctuations  of  the  composition  of  the  whole  fossil 
contents.  This  actual  fact  of  (6)  frequt  nt  difference  inrelative  abun- 
dance of  the  species  of  the  faunules  of  a  continuous  fauna  is  established 
by  the  statistics  already  givi  n. 

By  the  hypothesis  proposed  the  shif tings  are  adjustments  of  the 
species  to  constantly  but  in  general  slowly  shifting  conditions  of 
environment  of  the  life  of  the  species. 

It  is  believed  that  these  zones  of  different  sedimentation  might  be 
recognized  (if  we  had  the  whole  record  before  us)  all  around  the 
shores  of  such  a  marine  basin  as  we  have  now  under  investigation. 

It  is  supposed,  second,  that  the  difficulties  arising  from  correlation 
of  the  sediments  which  are  cut  through  by  sections  in  different  parts 
of  such  a  basin  are  due  in  great  measure  to  neglect  of  this  fact  of  utter 
difference,  as  far  as  adaptation  to  species  is  concerned,  in  the  sedi- 
ments synchronously  forming.  Across  the  central  part  of  New  York 
State  the  shifting  of  these  sediments  was  recognized  early  in  the 
eighties,  and  it  is  represented  in  the  region  about  Ithaca  and  imme- 
diately eastward  in  the  following  way: 

The  Hamilton  formation  is  found  underlying  the  whole  State,  reach- 
ing from  eastern  New  York  across  the  State  and  into  Ontario,  Canada. 
It  contains  a  rich  marine  fauna,  and  for  that  reason  is  clearly  tracea- 
ble wherever  it  appears. 

This  formation,  as  an  arenaceous,  sometimes  argillaceous,  shale, 
occupied  a  large  area  of  near-shore  bottom  of  a  sea  which  extended  over 
what  is  now  New  York  State.  The  sediments  became  more  calcareous 
on  passing  south  westward,  and  in  Ohio  and  Indiana  the  calcareous 
beds  increase,  the  limestone  conditions  of  the  Onondaga  continuing 
upward  after  the  time  of  occupation  of  the  region  by  the  Tropidolep- 
tus  carinatus  fauna.     Taking  the  presence  of  this  fauna  as  the  basis 


wili.iams.]  SHIFTING    OF    FAUNAS.  115 

of  discrimination  of  the  Hamilton  formation,  the  Latter  in  central 
New  York  is  followed  directly  by  the  Tnlly  limestone,  and  that  by  the 
Genesee  shale,  in  which  there  is  no  trace  of  the  Tropidoleptus  fauna. 
Farther  westward  this  cutting  off  of  the  fauna  takes  place  lower- 
down,  and  by  the  time  we  reach  Ohio  the  Tropidoleptus  fauna  is 
almost  entirely  wanting.  Still  farther  on,  the  highest  of  this  partic- 
ular series  of  marine  faunas  is  that  of  the  Onondaga. 

In  the  other  direction,  when  the  Genesee  shale  once  comes  in  it  is 
expressive  of  the  departure  of  the  Tropidoleptus  fauna  from  the 
region.  Following  the  Genesee  shale  eastward  we  find  it  gradually 
ceases  as  a  formation,  and  east  of  the  Chenango  Valley  very  slight 
traces  of  the  sedimentation  of  the  Genesee  formation  are  evident.  In 
that  region,  as  soon  as  the  thinning  and  insignificance  of  the  Genesee 
and  Tully  become  evident  in  the  column,  the  Tropidoleptus  fauna  is 
found  to  extend  upward  in  full  strength.  In  this  eastern  region  there 
is  evidence,  for  several  hundred  feet  of  the  succession — the  direct 
succession — of  the  Tropidoleptus  carinatus  fauna,  and  ils  continu- 
ance on  until  the  very  base  of  the  Oneonta  sandstone.  This  is  evi- 
dence of  shifting  of  the  faunas  eastward.  As  the  sedimentation  of 
the  black  shale  character  pushed  farther  eastward  the  Tropidoleptus 
fauna  was  also  crowded  farther  eastward,  and  in  the  later  part  of  the  life 
of  the  Tropidoleptus  fauna  its  geographical  distribution  was  restricted 
to  this  eastern  half  of  New  York  State,  the  Cardiola  speciosa  fauna 
prevailing  through  the  corresponding  strata  in  western  New  York. 

Now  the  next  clear  evidence  of  shifting  of  the  faunas  is  found  when 
the  red  shales  and  sandstones,  which  are  characterized  as  Oneonta 
sandstones,  came  in  in  Otsego  County.  Coincident  with  this  shov- 
ing in  of  the  shore  deposits  westward  we  find  the  forcing  of  the 
Tropidoleptus  fauna  also  westward  after  the  zone  of  the  Genesee 
shale  was  passed.  This  is  represented  in  the  Cayuga  Lake  section 
b}^  the  Ithaca  group  and  its  fauna,  which  is  called  the  Productella 
speciosa  fauna.  This  fauna  penetrates  somewhat  westward  of  Seneca 
Lake.  At  High  Point  the  dominant  species  are  of  another  fauna.  I 
have  thought  that  traces  of  the  Productella  speciosa  fauna  appear  as 
far  west  as  Hornellsville,  but  in  the  section  of  Genesee  Valley  no 
trace  of  the  fauna  has  been  discovered. 

The  shifting  in  the  other  direction,  toward  the  east,  is  evident  at 
the  Leiorhynclius  globuliforme  zone,  which  follows  in  the  strati- 
graphical  succession  above  the  horizon  at  which  the  Oneonta  sandstones 
cease  in  the  Chenango  Valley.  Here  is  indicated  a  shifting  back- 
ward of  the  faunas  which  were  so  dominant  in  the  region  of  the 
Cayuga  Lake  section  about  Ithaca  and  for  50  miles  eastward.  The 
shifting  is  indicated  by  the  withdrawal  of  the  red  sediments,  also. 
farther  eastward,  and  in  the  Ithaca  section  if  is  indicated  by  the 
cessation  there  of  the  Productella  speciosa  fauna,  followed  by  a  return 
of  the  species  of  the  Cardiola  speciosa  fauna  of  the  Portage  formation 


116  COEEELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

of  the  Genesee  Valley  in  a  long  stretch  of  about  500  feet  of  sediments 
above  the  fossiliferous  Ithaca  zone  in  the  hills  south  of  Ithaca. 

The  final  return  shifting  of  the  faunas  westward  is  seen  in  the  occu- 
pation of  eastern  New  York  by  the  red  sediments  of  the  Catskill 
formation.  This  incursion  of  the  red  sediments  took  place  before  the 
complete  extinction  of  the  Tropidoleptus  carinatus  fauna,  and  it  was, 
probably,  in  great  measure  the  cause  of  the  extinction  of  that  fauna. 
The  species  which  lived  on  shifted  westward,  and  in  the  eastern  coun- 
ties of  Pennsylvania  and  adjoining  borders  of  New  York  we  find  them 
represented  and  mixed  with  the  typical  Spirit)  r  disjunctus  faunas, 
which  occasionally  came  in,  intercalated  between  red  layers  of  the 
Catskill.  As  this  set  of  sediments  is  followed  farther  westward,  the 
red  sediments  also  pushed  farther  and  farther  westward,  until  they 
reached  the  position  of  Olean  and  corresponding  positions  in  Pennsyl- 
vania. But  during  the  Catskill  occupation  of  eastern  New  York  and 
Pennsylvania,  the  Spirifer  disjunctus  fauna,  pre  vailed  over  most  of 
the  western  half  of  these  Stales,  in  a  thousand  or  more  feet  of  sedi- 
ments, from  which  the  red  sediments  of  the  Catskill  are  almost 
entirely,  and  for  the  more  western  sections  entirely,  absent. 

Willi  each  shifting  of  the  sediments  or  faunas  it  is  not  simply  a  single 
kind  of  sediment  that  changes  its  position,  but  all  of  the  sediments 
change  t  heir  geographical  position  of  accumulation;  and  the  sequence 
of  faunas  (represented  in  any  particular  section  cut  through  them) 
presents  contrasts  which  have  led  to  much  confusion  in  making  the 
correlations.  There  is,  throughout  the  region,  a  gradual  succession 
of  faunas  and  species  constituting  the  faunas.  The  species  are  modi- 
fied, chiefly,  at  the  periods  when  the  shifting  took  place.  The  shift- 
ing does  not  result,  in  most  cases,  in  the  extinction  of  the  fauna,  as  is 
clearly  indicated  by  the  recurrence  of  the  species  in  the  successive 
stages. 

From  an  analysis  of  the  faunas  living  in  the  New  York  province 
during  Devonian  time,  we  are  led  to  believe  that  along  with  the  oscil- 
lat  ion  of  the  depth  of  the  bottom  below  the  surface  of  the  ocean  there 
occurred  shifting  of  the  faunas  as  corporate  wholes.  The  changes 
were  gradual,  but,  with  the  change  of  condition  of  the  bottom,  the 
species  of  the  whole  fauna  moved  together  in  the  direction  their  favor- 
able conditions  of  environment  was  taking.  Coincident  with  such 
forced  migration  there  was  modification  of  some  of  the  species,  noticed 
most  distinctly  at  first  in  change  in  the  dominance  of  individuals,  and 
followed  by  modification  of  those  which  maintained  their  strength 
and  vigor,  and  a  selection  of  those  varieties  best  adapted  to  endure 
the  new  conditions. 


CHAPTER   V. 

EQUIVALENCY  AS  INTERPRETED  BY  GEOLOGISTS. 

DIVERSITY  OF  INTERPRETATION. 

There  is  no  problem  in  geology  which  occasions  more  controversy 
than  that  of  determining  the  equivalency  between  the  rocks  or  forma- 
tions of  regions  separate  from  one  another.  In  stratigraphical  geol<  >gy 
this  may  be  said  to  be  the  great  problem  with  which  everyone  is  con- 
cerned until  it  is  settled;  and  when  it  is  settled  it  is  the  one  thing 
which  every  new  investigator  is  wont  to  think  he  has  a  right  to  criti- 
cise and  modify,  in  the  light  of  his  own  newly  discovered  facts.  If  I 
mistake  not,  the  chief  cause  for  this  disagreement  regarding  geolog- 
ical equivalency  is  the  unconscious  confusion  of  different  standards 
of  measurement  in  estimating  the  values  which  are  balanced,  and 
regarding  which  equality  of  value  is  predicated. 

One  man,  when  he  speaks  of  the  same  formation  (e.  g.,  the  Medina 
sandstone)  as  appearing  in  different  States  of  the  Union,  is  referring 
to  the  kind  of  lithological  material  of  which  the  rock  is  composed ;  it 
is  a  case  of  lithological  equivalency.  Another  man  is  thinking  of  the 
geological  time— the  time  when  the  formation  was  made — in  the  two 
regions;  this  is  contemporaneity  of  formations.  A  third  is  thinking 
of  the  likeness  of  the  fossil  forms  contained  in  the  rocks— fa  unal 
equivalency.  But  in  ordinary  discussion  it  is  rarely  considered  thai 
lithological  equivalency,  contemporaneity  of  formation,  and  fauna! 
equivalency  are  not  necessarily  the  same,  and  that  they  may  conflict 
with  each  other. 

In  order  to  make  clear  the  reason  for  such  confusion,  the  standards 
of  equivalency  in  the  case  of  geography  may  be  examined.  In  deal- 
ing with  geographical  facts,  there  are  three  ways  of  measuring  and 
defining  them.  A  particular  geographical  feature  may  be  defined  in 
each  of  three  ways.  In  order  to  define  tin'  geographical  position  of 
West  Rock,  for  example— an  elongated  hill  of  trap  rock  rising  to  an 
elevation  of  about  400  feet  above  tide  level— either  of  the  following 
statements  may  be  made: 

1.  It  is  situated  about  ^  miles  north  of  the  head  of  New  Haven  Bay, 
on  the  edge  of  the  New  England  coast,  opposite  the  central  part  of 
Long  Island  Sound. 

2.  It  is  situated  in  the  town  of  West ville,  New  Haven  County, 
Conn. 


118  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

3.  It  is  situated  on  the  meridian  of  41°  20'  north  latitude  and  on  the 
parallel  of  72°  57'+  west  longitude. 

From  this  illustration  it  is  evident  that  any  geographical  feature  on 
the  face  of  the  earth  may  be  defined  as  to  its  geographical  position  in 
three  distinct  ways — distinct,  because  the  locality  scale  may  be  any 
one  of  the  three  kinds  signified  in  the  foregoing  definitions. 

These  three  locality  scales  are : 

1.  A  geographical  locality  scale,  in  which  the  facts  are  the  present 
configuration  of  the  surface  of  the  earth,  chiefly  in  respect  to  alti- 
tude, or  distance  in  feet  above  or  below  sea  level. 

2.  A  political  locality  scale,  in  which  the  facts  are  the  political 
divisions  of  territory  as  defined  by  human  ownership  or  occupation. 

3.  An  astronomical  locality  scale,  in  which  the  facts  are  distances 
in  angular  degrees  or  minutes,  north  or  south  from  the  equator  of 
the  earth  and  east  or  west  from  an  arbitrary  standard  meridian  (that 
of  Greenwich). 

It  will  be  observed  that  the  only  one  of  these  standard  scales  which 
is  permanent,  fixed,  and  capable  of  use  with  precision  is  the  astro- 
nomical scale,  which  can  not  be  seen  on  the  surface  and  has  no  regard 
whatever  to  facts  upon  which  the  other  two  scales  are  constructed. 

I  have  referred  to  the  locality  scales  of  geograph}'  in  order  to  illus- 
trate more  vividly  the  differences  which  are  confused  when  a  time- 
scale  is  under  consideration  for  the  definition  of  geological  facts. 

The  geologist  is  using  three  time-scales  in  his  attempt  to  define  the 
chronological  relations  of  geological  events. 

1.  When  an  American  geologist  speaks  of  a  formation  in  Ohio  as 
the  Trenton  limestone,  or  in  the  Appalachian  region  speaks  of  the 
.Medina  sandstone,  or  the  Catskill,  or  Poeono,  he  is  using  a  time-scale 
in  which  the  basis  of  classification  is  the  fact  that  a  rock  of  a  particular 
kind  in  the  section  at  Trenton,  Medina,  or  in  the  Catskill  or  Poeono 
Mountains  is  assigned  to  a  definite  place  in  the  stratigraphical 
sequence  of  formations.  In  applying  the  name  to  a  formation  in  Ohio 
or  in  the  Appalachians,  he  is  attempting  to  affirm  equivalency  of  posi- 
tion in  a  stratigraphical  series  of  formations.  It  is  a  time  classification 
by  formations;  he  is  dealing  with  a  formational  time-scale. 

2.  Again,  in  describing  the  Niagara  of  America  as  equivalent  to  the 
Wenlock,  and  then  classifying  it  as  therefore  belonging  to  the  Silurian 
age,  the  geologist  is  using  an  entirely  distinct  basis  of  classification. 
The  basis  of  his  determination  now  is  equivalency  of  the  faunal  combi- 
nation of  fossil  species  found  in  the  rocks  of  the  two  formations.  In 
this  case  stratigraphical  or  lithological  characters  are  not  in  evidence, 
but  only  the  organisms  which  were  living  when  the  sediments  com- 
posing the  rocks  were  laid  down.     It  is  now  a  faunal  time-scale. 

3.  There  is  still  a  third  method  of  defining  geological  events  chrono- 
logically. The  question  arises  in  mapping  the  rocks  of  a  region,  where, 
in  the  column  of  formations,  shall  the  boundary  be  drawn  between 
two  systems,  viz,  between  the  Silurian  and  Devonian?     This  question 


wili.tams]      EQUIVALENCY    AS    INTERPRETED    BY    GEOLOGISTS.  119 

was  settled  in  the  case  of  the  Appalachian  sheets  of  the  U.  S.  Geolog- 
ical Survey  by  drawing  the  line  in  the  midst  of  the  Monterey  sandstone. 
In  the  legend  of  the  map  the  Monterey  sandstone  is  called  neither 
Silurian  nor  Devonian,  but  transitional.  In  the  text,  the  forma- 
tion is  defined  as  containing  Oriskany  fossils.  Without  entering 
into  the  merits  of  the  case,  this  is  an  illustration  of  using  a  scale  which 
is  neither  f ormational  nor  faunal.  A  formation  is  a  distinct  lithological 
unit,  but  its  base,  as  thus  defined,  is  placed  below  the  boundary  line 
between  the  two  systems,  and  its  top  is  above  the  boundary  line.  This 
boundary  line  is  therefore  a  theoretical  one,  which  does  not  occur  in 
the  stratigraphical  series  as  mapped  on  the  sheet,  and  the  scale  to 
which  it  is  referred  is  the  standard  geological  time-scale. 

This  particular  standard  is  based  upon  a  single  section  in  Wales, 
where  the  earliest  recognized  boundary  was  drawn  between  the  Silu- 
rian and  overlying  Old  Red  sandstone,  and  however  differently  the 
sequence  of  formations  or  faunas  may  occur  in  any  other  regions,  the 
grand  divisions  of  time — Cambrian,  Silurian,  Devonian,  Carboniferous, 
etc. — are  arbitrarily  drawn,  determined  as  near  as  may  be  by  compar- 
ing all  the  points  of  geological  history  for  the  two  separate  regions. 

In  the  previous  pages  the  facts  are  presented  by  which  the  applica- 
tion of  the  rules  for  establishing  equivalency  may  be  illustrated. 

In  the  case  of  the  Devonian  formations  and  faunas  of  the  New  York 
province  the  different  kinds  of  equivalency  may  be  stated  with  some 
degree  of  precision. 

In  a  formational  time  scale  the  units  compared  are  lithological  units. 
Examples  of  such  units  are  the  black  Genesee  shale,  the  Huron 
shales  of  Ohio,  the  Tully  limestone,  the  Catskill,  the  Oneonta,  and 
the  Hamilton  formations.  The  questions  of  formational  equivalency 
involve  two  points — lithological  and  stratigraphical  equivalency. 
In  two  neighboring  sections  there  may  occur  50  feet  of  red  sandstones 
in  one,  which  are  equivalent  to  75  feet  of  red  sandstone  in  the  other 
section ;  this  is  a  case  of  lithological  equivalency.  In  two  other  sections 
50  feet  of  red  sandstones  in  one  may  be  equivalent  to  30  feet  of  green- 
ish shales  and  flags  in  the  other;  this  is  a  case  of  stratigraphical  equiva- 
lency. From  the  examples  given  in  discussing  the  Devonian  faunas 
it  is  evident  that  the  lithological  and  stratigraphical  equivalency  may 
coincide  or  may  be  discordant. 

In  ordinary  cases  it  is  presumed  that  lithological  and  stratigraphical 
equivalency  coincide.  Such  is  the  case  when  the  Tully  limestone  is 
followed  along  the  line  of  its  outcrops.  When  its  calcareous  character 
becomes  so  faint  as  to  be  indistinguishable  in  the  series  of  si  rata,  the 
formation  is  said  to  cease.  According  to  the  older  habits  of  treatment 
of  such  cases  the  Tully  limestone  is  supposed  to  thin  and  run  out  to 
a  feather  edge,  thus  finding  its  equivalency  in  the  column  between 
the  subjacent  and  superi  m  posed  formations.  According  to  the  inter- 
pretation here  proposed  the  change  would  be  described  as  a.  Lithological 
change— a  change  in  the  character  of  the  sediments  by  increaseof  the 


120  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

argillaceous  and  arenaceous  over  the  calcareous  elements — until  the 
former  prevailed  to  the  exclusion  of  the  latter.  The  equivalent  strata 
of  the  limestone  would  in  the  second  locality  appear  as  shales  and 
sandstones;  and,  for  instance,  the  actual  stratigraphical  equivalent  of 
the  Tully  limestone  in  Chenango  and  Otsego  counties  may  be  supposed 
to  be  twice  as  thick  as  the  Tully  itself  and  not  distinguishable  litho- 
logically  from  what  lies  below  or  above  it.  Such  a  formation  is,  strictly 
speaking,  but  a  member,  and  the  reason  for  separating  it  from  the 
Hamilton  formation  is  the  appearance  in  it  of  diagnostic  species  not 
belonging  to  the  general  Tropidoleptus  carinatus  fauna,  but  which 
immigrated  into  the  region  from  another  fauna.  Prosser  described 
such  a  case  in  Otsego  Count}7,  in  section  21,  east  of  Noblesville.  The 
rocks  are  described  as  "smooth,  greenish  sandstones,  in  the  midst  of 
which  are  block}7  shales  in  which  Rhynclionella  venustula  Hall  is 
common  ;"a  i.  e. ,  a  characteristic  species  of  the  Tully  limestone.  Asso- 
ciated with  this  species  are  Spirifer  (mucrondtus)  penned  us  and  Tro- 
[>i<h>h  plus  ca rina his,  two  characteristic  species  of  the  Hamilton  forma- 
tion. The  rocks  below  are  bluish  shales;  those  above  are  arenaceous 
shales.  The  thin  "  blocky  shales  with  Rhynchonella  venustula  (Hypo- 
thyris  cuboides)"  may  be  regarded  as  the  attenuated  stratigraphical 
equivalent  of  the  Tully  limestone,  but  the  facts  favor  the  opinion  that 
although  this  holds  the  attenuated  representative  of  the  fauna  of  the 
Tully  limestone,  the  ad  ual  st  rat  [graphical  equivalent  of  the  formation 
includes  more  or  less  of  the  blue  shales  below  and  the  arenaceous 
shales  above. 

An  exanqne  of  the  discordance  bet  ween  lithologieal  and  stratigraph- 
ical equivalency  is  given  1)}'  the  Oneonta  formation.  The  Oneonta 
sandstone  of  Otsego  County  is  shown  to  occupy  the  same  position  in 
the  column  which  the  Ithaca  formation  holds  in  the  section  at  Ithaca. 
The  Oneonta  formation  is,  therefore,  the  stratigraphical  equivalent 
of  part  of  the  Ithaca  formation,  but,  lithologically,  it  is  the  equivalent 
of  the  lower  Cat  skill.  In  the  same  way  Die  Chemung  formation  of  the 
Genesee  Valley  section  is  stmtigraphically  equivalent  to  the  Catskill 
formation  of  eastern  Pennsylvania,  in  part,  to  the  Erie  shales  of  Ohio. 
But  lithologically  the  Ohio  shales  are  equivalent  to  the  Portage  for- 
mation of  New  York.  A  formation,  therefore,  may  be  stratigraphically 
equivalent  to  one  portion,  while  lithologically  it  is  equivalent  to 
another  portion  (either  higher  or  lower)  of  the  geological  column. 

CORRELATION   OF  THE  DEVONIAN   FORMATIONS  OF  OHIO, 
WESTERN   NEW   YORK,   AND   EASTERN   NEW  YORK. 

The  foregoing  proposition  may  be  illustrated  by  tabulating  the 
formations  of  Ohio,  western  New  York,  middle  New  York,  and  east- 
ern New  York,  along  a  west-east  series  of  outcrops,  as  shown  in  PI.  I. 

"  ( 'lassification  and  distribution  of  the  Hamilton  and  Chemung  series  of  central  and  eastern 
New  York:  Fifteenth  Ann.  Rept.  State  Geologist  New  York,  1895,  Part  I,  p.  183. 


11£ 


fed 


3S 


:&'i 


sho  w      a 


«    z  s     Jt 


iJ. 


\C5 


s-f^ 


"L 


8/ 


3* 


1* 


7~^T 


u  o     J  •_, 

dl 

J  ill 

5*     a 

«/ 

s 

9* 

§ 

§ 

s 

'T 

1       * 

j 

5 1 
1 

5 

o 

".-Si 

•  Sid 

0) 

q 

3 

g 

5 

CMI 

1                         / 
1                        / 
1                       / 
1                      ' 

j 

l                 i 

!                      i'ejw?/ 

!    1    li'asl 

i        o        <u  i  o3  £  'a 

UJ 

I 

:; 

K     |  + 

1 

"|  ? 

1 

[3r=+-  4; 

IW«i  1  i     s  Mi<t 

o  fc  DQ 


ton  ~',ia  j>i  i; 
fi  -j  ■£  ,c   l>  i  « 

Si's  i  §  ^'.5 


J!^53ss«3 


<!  1 


wti.liams]      EQUIVALENCY    AS    INTERPRETED    BY    GEOLOGISTS.         121 

The  sections,  A  to  I,  are  arranged  in  order  along  a  curved  line  ex- 
tending from  Licking  County,  Ohio,  northeastward  toward  James- 
town, N.  Y. ;  thence  eastward  to  Ithaca;  thence  nearly  east  ward  to 
Norwich;  thence  southeastward  to  the  Delaware  Water  Gap  near 
Stroudsburg,  Pa.  These  sections  are  placed  in  approximately  the 
relative  distances  apart  which  the  natural  sections  occupy  along  such 
a  line.  Such  a  line  theoretically  represents  a  section  at  right  angles 
across  the  successive  zones  of  conditions  of  sea  bottom  out  from  a 
shore  which  had  a  general  trend  parallel  to  the  present  Atlantic 
coast  and  the  general  Appalachian  axis.  The  total  distance  repre- 
sented is  about  500  miles. 

The  several  sections  are,  for  thickness  and  classification  of  forma- 
tions, based  upon  official  survey  reports,  revised  in  some  cases  by 
special  surveys;  and  the  range  of  the  fossil  faunas  has  been  deter- 
mined by  special  detailed  investigations,  accomplished  chiefly  by  the 
persons  named  below,  viz: 

A.  Licking  County,  Ohio,  revised  by  Orton,  Herrick,  and  Prosser. 

B.  Meadville,  Crawford  County.  Pa. ,  and  across  Erie  County,  Pa. ;  Second  Penn- 
sylvania survey  (I.  C.  White),  Q4;  revision  by  E.  M.  Kindle  and  H.  S.  Williams. 

C.  Jamestown,  Chautauqua  County,  N.  Y.,  and  Garland ,  Warren  County, Pa.; 
Second  Pennsylvania  survey  (Carll)  1 4,  and  G.  D.  Harris;  range  of  faunas,  E.  M. 
Kindle. 

D.  Warren, Warren  County,  Pa.;  Second  Pennsylvania  survey  (Carll)  I  4,  range 
of  faunas,  E.  M.  Kindle  and  H.  S.  Williams. 

E.  Genesee  Valley  and  Olean,  N.  Y. ;  H.  S.  Williams;  section  revised  by  E.  M. 
Kindle  and  M.  L.  Fuller. 

F.  Ithaca  and  Cayuga  Lake,  N.  Y.;  H.  S.  Williams,  E.  M.  Kindle,  and  H.  F. 
Cleland. 

G.  Chenango  River  Valley,  New  York;  OS.  Prosser  and  H.  S.  Williams. 

H.  Catawissa,  Columbia  County,  Pa. ;  Second  Pennsylvania  survey  (I.  C.  White) 
G  7;  range  revised  by  E.  M.  Kindle. 

I.  Monroe  and  Pike  counties,  along  Delaware  River,  Pennsylvania;  Second 
Pennsylvania  survey  (I.  C.  White)  G  6;  range  revised  by  C.  S.  Prosser. 

The  range  of  the  faunas  is  expressed  by  the  cross  lines  marked  1  to 
5  and  the  letter  R. 

The  line  marked  1  represents  the  upper  Limit  of  range  of  the 
typical  fauna  of  the  Onondaga  limestone. 

Line  2  is  the  upper  limit  of  the  pure  I  Iain  ill  on  fauna/' 

Line  3  is  the  lower  limit  of  the  Chemung  fauna. 

Line  4  is,  for  the  western  sections,  the  lower  limit  of  the  Waverly 
fauna;  in  the  Ithaca  section  (F)  and  the  sections  farther  east,  il  is 
the  highest  level  at  which  definite  I  races  of  the  Chemung  fauna  have 
been  detected. 

Line  5  is  the  base  of  the  Olean  conglomerate  (E)  and  of  other  con- 
glomerates regarded  by  stratigraphy's  to  be  its  equivalents.  In  the 
easternmost,  section  (1)  it-  is  called  Pottsville  conglomerate  series. 


"In  section  F  this  Line,  by  mistake,  is  drawn  to  cross  the  section  al  top  instead  of  a1  bottom  of 
the  Tnlly  limestone. 


122  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

The  line  marked  R  is  the  horizon  at  which  the  first  well-marked 
red  beds  appear  in  the  sections  on  going  up,  above  which  the  so-called 
Catskill  fauna  appears.  In  general,  the  figures  in  the  columns 
express  the  thickness  in  feet  assigned  to  each  formation,  the  names 
of  which  are  placed  opposite  them  as  applied  in  the  several  regions 
through  which  the  sections  pass. 

These  facts  may  be  expressed  in  terms  of  equivalency,  as  follows: 
At  the  base  of  this  particular  series,  the  calcareous  Delaware  forma- 
tion, in  its  upper  measures,  contains  traces  of  the  Tropidoleptus  fauna. 
In  western  New  York  the  Hamilton  formation  is  composed  of  argilla- 
ceous, calcareous  shales,  and  in  eastern  New  York  it  is  arenaceous, 
but  not  so  strongly  so  as  to  change  the  fauna.  The  black  Huron 
shales  of  Ohio,  following  the  Delaware  limestone  and  shading  off 
gradually  into  the  green  shales  of  the  Erie,  occupy  the  interval 
which,  in  western  New  York,  is  made  up  of  the  Marcellus  shale, 
Hamilton,  Tully,  Genesee,  Portage,  and  some  of  the  Chemung  of 
western  and  central  New  York.  In  central  New  York  these  find 
their  equivalent  in  the  Marcellus,  Hamilton,  Tully,  Genesee.  Farther 
east  the  Tully  and  Genesee  are  wanting,  as  formations,  or  are  repre- 
sented by  Hamilton  and  Sherburne  formations.  The  Ithaca  is  in  part 
represented  by  the  Oneonta,  and  its  upper  part  is  represented  by 
the  so-called  Chemung  of  Otsego  and  neighboring  counties.  The 
Chemung  is  represented  in  that  region  by  the  Catskill.  Still  higher 
up,  the  space  from  the  black  Cleveland  shale  of  Ohio  up  to  the  Logan 
conglomerate  is  represented  iu  western  New  York  and  Pennsylvania 
by  the  upper  Chemung,  Panama  conglomerate,  flat-pebble  conglomer- 
ate, and  beds  at  Olean  holding  Spirifer  disjunctus,  running  up  to  the 
base  of  the  Olean  conglomerate.  Farther  east  this  interval  is  made 
up  of  the  "Catskill,  and  the  probabilities  are  (though  the  facts  to  sup- 
port the  opinion  are  not  positively  in  sight,  fossils  being  out  of  evi- 
dence) that  the  Pocono  and  Mauch  Chunk  are  also  the  representatives 
of  this  same  AYaveiiy  group  (or  a  portion  of  it)  of  Ohio. 

The  second  kind  of  equivalency  has  regard  to  the  faunal  time  scale. 
Equivalency  of  faunas  may  be  illustrated  in  a  definite  case  by  saying 
that  the  Tropidoleptus  fauna  may  be  recognized  over  a  wide  territory 
by  its  dominant  species,  but  this  alone  is  not  sufficient  to  identify  the 
formation.  For  instance,  in  the  case  of  the  Tropidoleptus  fauna  of 
eastern  New  York  we  have  airead3r  noted  a  list  of  12  species  which 
are  dominant  throughout  the  fauna,  as  exhibited  in  the  different  parts 
of  the  State.  These  are  dominant  on  the  basis  of  geographical  dis- 
tribution, and  therefore  may  be  regarded  as  representative  species  of 
the  Tropidoleptus  fauna,  not  necessarily  of  the  Hamilton  formation. 
Nevertheless,  when  in  central  and  western  New  York  we  pass  above 
the  formation,  which  is  sharpty  defined  in  the  sections,  both  litholog- 
ically  and  faunally — so  there  is  no  possible  doubt  as  to  the  termina- 
tion of  the  formation  in  these  western  sections — we  find  that  the  fauna 


Williams.]     EQUIVALENCY    AS    INTERPRETED    BY    GEOLOGISTS.  123 

which  appears  in  the  Ithaca  formation  contains  all  of  these  represent- 
ative species  of  the  Hamilton  formation,  thus  making- a  faunal  equiva- 
lency with  known  discordance  as  to  formational  equivalency.  It  is 
known  that  stratigraphically  the  Ithaca  formation  is  not  equivalent 
to  the  Hamilton  formation.  However,  if  we  were  to  detect  the  species 
named  in  the  dominant  Hamilton  list  in  a  section  in  Indiana,  the 
inference  would  be  drawn  at  once  that  the  Hamilton  fauna  was  pres- 
ent. The  truth  is  that  the  Tropidolepius  fauna  is  present,  but  that  the 
Hamilton  formation  may  or  may  not  be  represented  in  Indiana.  The 
evidence  of  the  equivalency  of  the  Sellersburg  formation  with  the 
Hamilton  formation  in  Indiana,  furnished  by  the  presence  of  the  few 
specimens  of  the  Tropidoleptus  fauna,  is  not  so  great  as  the  evidence 
of  equivalency  of  the  Ithaca  formation  with  the  Hamilton  in  New  York. 
This  case  brings  out  the  distinction  between  faunal  and  formational 
equivalencies.  It  also  illustrates  the  importance  of  the  recognition  of 
some  other  basis  than  simple  presence  of  species  in  order  to  certify  the 
fauna  to  which  they  belong.  The  facts  are  not  present  for  carrying 
correlations  by  this  careful  method  through  the  whole  series  of  forma- 
tions known  to  occur  within  the  boundaries  of  the  intercontinental 
basin,  but  sufficient  is  known  to  make  it  certain  that  the  general  faunas 
prevailing  in  one  section  of  the  basin  during  a  period  of  time,  the 
formational  equivalency  of  which  may  be  clearly  established  in 
another  section,  are  faunally  diverse  in  the  two  sets  of  sediments 
representing  the  same  period  of  time. 


CHAPTER    VI. 
THE  BIONIC  VALUE   OF  FOSSILS. 

GENERAL    STATEMENT. 

The  essential  difference  between  the  three  classes  of  evidence  upon 
which  geologists  base  their  determinations  of  equivalency  of  com- 
pared formations  having  been  demonstrated,  a  few  words  may  be 
said  regarding  the  nature  of  the  evidence .  by  which  fossils  record 
definite  epochs  of  geological  time. 

Uniformity  in  rock  constitution  we  all  understand,  and  it  requires  no 
special  analysis.  Stratigraphical  equivalency  is  readily  perceived  to 
be  based  upon  structural  uniformity;  and  in  describing  two  formations 
as  stratigraphical  equivalents  we  mean  that  they  are  the  same  strue- 
tural  parts  of  the  earth's  crust.  In  making  determinations  of  faunal 
equivalency,  however,  the  presence  of  one  or  several  fossils  is  not 
sufficient  to  establish  close  correlation,  for  the  reason  that  the  same 
fossil  species  may  occur  throughout  many  feet  of  thickness  of  sedi- 
ments, and  anywhere  in  that  range  may  exhibit  the  same  fossil  forms. 
It  becomes  necessary  to  deal  with  the  aggregate  fauna  regarding 
which  the  modifications  are  constantly  taking  place.  Not  only  must 
we  treat  of  fossils  as  aggregates,  but  we  must  have  some  means  of 
measuring  the  aggregates  other  than  the  scientific  names  of  the  fossils. 
While  their  names  are  essential  and  cover  a  great  many  particulars, 
in  order  to  extract  the  evidences  of  time  we  must  be  able  to  deal  spe- 
cifically with  those  elements  which  are  associated  directly  with  the 
passage  of  time. 

In  the  previous  pages  I  have  referred  to  the  bionic  values  of  fossils, 
and  have  arrayed  a  mass  of  statistics,  gathered  and  formulated  in 
such  ways  as  to  exhibit  these  bionic  relations,  and  the  reader  will  now 
be  ready  to  consider  more  particularly  what  is  the  nature  of  this 
special  method  of  treatment  of  fossils  as  evidence  of  passage  of  time. 

Fossils,  as  morphological  records  of  the  living  organisms  of  the  past, 
are  of  inestimable  value  in  reading  the  history  not  only  of  the  organ- 
isms themselves,  but  of  the  conditions  of  the  environment  through 
which  they  struggled  and  to  which  they  were  adjusted.  But  form 
such  as  the  fossil  expresses,  and  in  general  such  as  is  expressed  by 
the  hard  parts  of  all  organisms,  is  extremely  complex.  It  is  impos- 
sible to  describe  it  in  geometrical  terms,  as  may  be  done  in  the  case 
of  minerals.  Although  descriptions  of  form  may  be  given  which  will 
124 


Williams.]  BIONIC    VALUE    OF    FOSSILS.  125 

convey  some  idea  of  the  important  elements  of  form,  it  is  actually 
necessary  that  either  the  original  specimen  or  drawings  illustrating 
the  form  be  used  to  convey  to  the  mind  the  meaning  of  the  terms  of 
the  description. 

It  becomes  important,  therefore,  for  stating  scientifically  the  histor- 
ical relations  of  organisms,  to  find  some  method  of  measuring  the  dif- 
ference between  one  fossil  and  another  which  shall  have  mathematical 
value  and  be  capable  of  expression  in  mathematical  terms. 

In  the  crystal  the  relations  of  the  faces  to  each  other  may  be 
expressed  in  degrees  and  minutes  of  angle  borne  by  the  planes  to 
each  other,  and  their  extent  may  be  measured  in  millimeters.  The 
chemical  elements  of  which  they  are  composed  may  be  expressed  in 
percentages  of  the  total  quantity  of  matter  in  the  individual  crystal, 
and  these  elements  may  be  compared  by  their  atomic  weights  or  be 
expressed  in  terms  of  specific  gravity.  It  is  the  form  of  a  fossil  which 
expresses  the  qualities  of  the  organisms,  but  this  form  can  not  be 
expressed  mathematically,  nor  is  it  coordinate  with  composition. 
Degree  of  complexity  of  organization  is  of  prime  importance  in  meas- 
uring the  rank  of  the  organisms  in  systematic  classification.  This 
degree  of  complexity,  or  amount  of  differentiation  of  structure,  which 
is  the  basis  of  systematic  classification,  is  evidence  of  the  amount  of 
evolution  through  which  the  ancestors  of  an  individual  have  passed. 

For  instance,  the  complex  structure  of  the  crayfish  presents  the 
morphological  evidence  of  its  taxonomic  rank.  It  holds  a  higher  rank 
in  classification  than  does  the  trilobite.  While  thus  much  is  known 
and  is  distinguishable  in  terms  of  form  and  use  of  organs — or,  to  speak 
abstractly,  in  terms  of  morphological  characters— it  is  very  difficult  to 
express  in  mathematical  terms  the  degree  of  difference  or  the  relative 
rank  of  the  organisms.  In  seeking  for  some  such  terms  the  practice  in 
physics  and  chemistry  may  be  studied.  Both  physics  and  chemistry 
have  reached  some  degree  of  mathematical  precision  in  expressing 
values  of  their  phenomena  by  the  adoption  of  arbitrary  units,  such 
as  pound  and  foot,  of  which  there  can  be  preserved  visible  standards 
for  comparison.  Another  set  of  standards  are  measures  of  exertion 
of  force  which  is  not  visible  but  is  capable  of  record  in  terms  of  the 
visible  standards,  pound  and  foot,  with  the  help  of  the  measures  of 
time,  duration,  and  motion  in  space.  Such  standards  are  the  dyne 
and  the  ohm.  When  it  is  sought  to  measure  the  relative  values  of 
organisms,  although  their  bodies  are  composed  of  chemical  elements, 
it  is  found  that  their  values  are  more  than  atomic.  Although  1  hey  are 
mechanically  constructed  and  act  in  accordance  with  physical  laws  of 
matter,  their  values  can  not  be  expressed  in  terms  of  physics. 

The  idea  that  the  survival  of  organisms  in  competitive  struggle  is 
determined  by  the  measure  of  vital  energy  exhibited  by  the  several 
competitors  furnishes  a  suggestion  as  to  the  kind  of  measure  by 
which  the  values  of  organisms  may  be  compared. 


126  COKRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

Since  it  takes  an  appreciable  length  of  time  for  an  organism  to 
develop  to  maturity  the  structure  by  which  it  carries  on  its  living 
processes,  and  as,  secondly,  every  individual  organism  develops  its 
form  elements  by  passing  from  a  formless  stage  into  a  more  and  more 
complex  morphological  stage,  these  two  elements,  time  and  individual 
development,  offer  promise  of  some  satisfaction  for  the  measurement 
of  organic  values,  which  may  be  considered  mathematically. 

Organisms  are  not  to  be  measured  by  the  amount  or  kind  of  matter 
of  which  their  bodies  are  constructed,  but  by  the  disposition  and  use 
they  make  of  the  matter  within  the  scope  of  their  activities.  It  is 
the  shape  of  the  lobster's  claw,  not  its  chemical  constitution,  which  is 
significant. 

Following  out  this  line  of  search,  we  notice  that  the  vigor  expressed 
by  the  coming  to  birth  and  the  growing  to  maturity  of  a  single  organ- 
ism is  repeated  when  it  reproduces  itself  in  a  second  generation. 
Whatever  value  be  imagined  as  the  value  of  the  life  power,  force,  or 
energy  by  which  a  single  germ  goes  on  to  maturity,  the  value  is 
doubled  when  another  generation  follows,  and  trebled  on  the  third 
generation.  Generation  becomes  thus  the  measure  of  a  certain  funda- 
mental ability  of  organic  bodies,  and  each  individual  organism  stands 
for  the  exertion  of  a  unit  of  such  force.  A  fossil  individual  is  the 
measure  of  this  unit  of  organic  energy  as  much  as  a  living  individual. 

Again,  if  each  case  of  reproduction  of  an  organic  individual  were 
an  exact  repetition  of  the  preceding  case,  all  organisms  would  be  alike. 
We  assume  that  difference  in  the  forms  of  organisms  is  to  be  accounted 
for  by  a  change  in  the  processes  by  which  the  mature  body  is  con- 
structed in  the  course  of  individual  development. 

If  the  constructive  form  of  the  adult  individual  organism  be  an 
expression  of  a  unit  of  vital  force,  it  may  be  assumed  that  the  diver- 
sion of  the  process  of  development,  so  as  to  modify  the  construction 
and  form,  is  the  expression  of  another  unit  of  force  of  some  propor- 
tionate  relation  to  the  first  unit. 

If  organic  generation  goes  on  for  100  generations  without  noticeable 
deviation,  this  second  mode  of  energy  may  be  supposed  to  be  less  than 
if  some  deviation  be  noticed  in  the  course  of  10  generations.  The 
evolutional  energy  expressed  in  the  deviation  from  a  given  form  in 
the  course  of  repeated  generations  is  of  the  same  nature  as  that 
expressed  by  the  development  of  the  germ  to  adulthood,  since  it  is 
morphologically  an  acquirement  of  structure  or  of  difference  of  form. 
This  form  is  visible  and  is  preserved  in  the  fossil  as  well  as  expressed 
in  the  living  organism.  Hence  it  is  evident  that  difference  in  form, 
when  it  is  combined  with  numbers  of  generations  taken  for  producing 
the  difference,  becomes  a  means  by  which  the  relative  values  of  organ- 
isms may  be  compared.  Difference  in  form  is  the  basis  of  classifica- 
tion of  organisms  in  systematic  zoology  and  systematic  botany.  In 
these  sciences  relative  difference  in  form  is  expressed  by  the  terms  of 


williams.]  BIONIC    VALUE    OF    FOSSILS.  127 

taxonomic  classification,  viz,  species,  genus,  family,  order,  class, 
branch. 

Out  of  these  several  terms  which  have  actual  visible  expression  in 
nature  (viz,  difference  in  form,  expressed  in  terms  of  species,  genus, 
family,  etc.,  in  systematic  classification;  difference  in  generation,  ex- 
pressed by  number  of  individuals  of  a  kind ;  and  number  of  genera- 
tions following  each  other  without  specific  modification)  may  .be  elab- 
orated a  means  of  expressing  the  relative  values  of  living  organisms 
in  mathematical  terms. 

These  values  may  be  called  b ionic,  implying  the  energy  values  of 
living  beings,  rather  than  the  values  of  their  mechanical  powers  or  of 
their  chemical  constitution,  since  development  from  germ  to  adult 
and  evolution  from  one  to  another  specific  form  are  phenomena  asso- 
ciated only  with  living  organisms;  and  the  term  bion  may  be  used  to 
express  the  idea  of  such  a  unit  of  vital  force. 

To  distinguish  this  mode  of  expressing  the  energy  peculiar  to  living 
organisms  from  the  other  modes  of  energy  expressed  by  machines 
and  in  chemical  reaction  of  nonliving  bodies,  the  energy  may  be 
spoken  of  as  bionic  energy.  It  is  evident  that  the  bionic  energy  of 
organisms  greatly  differs  for  different  organisms;  but  it  is  not  yet 
known  that  the  differences  may  not  be  actually  an  expression  of  the 
number  of  generations  through  which  the  ancestors  have  passed,  and 
thus  actually  may  indicate,  mathematically,  the  true  bionic  value  of 
the  species  or  race  at  the  stage  in  which  it  is  examined. 

THE  TERMS  "SPECIES,"  "RACE,"  AND   "GENERATION." 

In  order  to  discuss  this  problem,  we  are  forced  to  use  the  term  species 
in  a  somewhat  special  sense.  Species,  when  contrasted  with  individual 
and  genus,  refers  to  an  aggregate  of  individuals  possessing  like  mor- 
phological characters.  But  when  we  describe  a  fauna  as  composed  of 
ten  or  twenty  or  a  hundred  species,  species  is  used  in  a  different  sense. 
We  are  not  dealing  with  the  aggregate,  but  with  the  specific  charac- 
ters. Each  individual  is  then  a  particular  species  or  belongs  to  a  par- 
ticular species.  Moreover,  each  individual  in  this  latter  sense  is  not 
only  a  species,  but  a  genus,  family,  and  class. 

Bearing  in  mind  this  distinction,  we  find  the  individual  to  be  an 
aggregate  of  cells,  parts,  and  organs,  and  the  particular  way  in  which 
these  cells,  parts,  and  organs  shape  themselves  in  the  adult  deter- 
mines to  what  species  and  genus  the  individual  belongs.  But  the 
individual  also  starts  as  a  germ  and  becomes  an  adult,  and  as  an  indi- 
vidual dies,  i.  e.,  loses  its  individuality.  The  individual,  thus,  is  a 
temporary  expression  of  the  species,  and  in  considering  time  values 
it  is  necessary  to  make  distinction  between  the  species  as  individuals 
and  the  species  as  a  race. 

The  species  continues  to  live  after  the  individual  representative  of 
it  has  perished,  and  species  as  a  time  measure  is  better  expressed  by 


128  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

the  term  race.  So  it  is  particularly  the  single  generation  rather  than 
the  single  individual  that  we  have  in  mind  when  the  time  value  of 
an  individual  is  under  consideration. 

If  we  could  actually  know  the  number  of  generations  it  takes  to 
accomplish  changes  sufficient  to  be  marked  by  describing  the  two 
extreme  individuals  as  of  different  species,  then  we  could  express  by 
such  a  number  the  magnitude  of  difference  between  the  time  values 
of  the  individual  and  of  the  species.  The  best  we  can  do  is  to  state 
that  the  two  measures  are  of  a  different  order  of  value.  We  may  state 
that  the  time  length  during  which  the  average  species  reproduces 
its  kind  without  appreciable  deviation  in  its  specific  character  is 
measured  by  thousands  and  possibly  millions  of  generations,  while  a 
single  generation  measures  the  time  length  of  the  first  order  in  little- 
ness of  value  associated  with  the  individual.  If  we  could  deal 
with  it  in  geology,  the  life  period  of  the  individual  would  be  the 
primary  unit  of  the bionic system  (monobiochron).  But  as  this  can  not 
be  ascertained  by  the  study  of  fossils— dead  remains  of  organisms — 
we  must  take  for  the  lowest  practical  bionic  unit  some  unit  which 
is  capable  of  expression  by  fossils  (dibiochron).  This  shortest  lapse 
of  time,  to  which  the  fossils  themselves  may  give  expression,  is 
associated  with  the  continuous  life  of  the  species,  and  may  be  con- 
ceived of  as  directly  determined  by  the  relative  vigor  maintained  by 
the  individuals  struggling  with  one  another  at  the  particular  point  of 
time  recorded.  So  long  as,  at  a  particular  spot  (a),  under  what  may 
be  supposed  to  be  unchanged,  local,  environmental  conditions  (b),  the 
relative  number  of  individuals  of  each  species  (c),  with  the  same  corn- 
parat  ive  size  and  proportions  of  form  (d),  continues  unchanged,  so  long 
a  certain  small  unit  of  time  may  be  considered  to  have  elapsed.  This 
is  called  a  dibiochron,  because  it  is  the  measure  of  the  second  order 
of  appreciable  magnitude  of  the  expression  of  the  bionic,  or  endur- 
ance qualities  of  the  organisms  whose  fossil  remains  are  examined. 

The  definition  of  terms  was  given  in  a  previous  paper",  an  extract 
of  which  will  explain  the  sense  in  which  the  terms  are  used: 

In  order  to  isolate  this  time  quality  I  have  proposed  to  speak  of  it  as  the  bionic 
quality  or  value  of  the  organism.  The  bionic  quality  of  an  organism  may,  then, 
be  defined  as  its  quality  of  continuing,  and  repeating  in  successive  generations, 
the  same  morphologic  characters.  *  *  *  And  if  we  should  adopt  the  name 
chron  to  apply  to  geological  time-units  in  general,  and  biochron  to  the  units  whose 
measure  is  the  endurance  of  organic  characters,  we  have  a  means  of  constructing 
a  system  of  nomenclature  which  will  express  what  is  now  known  of  geological 
time  relations,  and  (more  important  still),  which  will  serve  as  an  aid  in  accumu- 
lating the  necessary  statistics  to  perfect  the  geological  time-scale. 

Order  of  magnitude  of  bionic  units. — In  expanding  this  system  of  nomenclature 
the  following  table  will  indicate  the  principle  upon  which  the  fundamental  units 
of  time  value  will  be  discriminated  and  named.  The  time-unit  of  lowest  rank 
will  he  based  upon  the  life  endurance  of  an  individual  organism;  the  amount  of 


«  Jour.  Geol.,  Vol.  IX,  p.  579. 


williams.]  BIONIC    VALUE    OF    FOSSILS.  129 

organic  vigor  expressed  by  the  preservation  of  the  individual  life  constitutes  a 
bionic  unit  of  simplest  or  lowest  rank;  the  individual,  therefore,  is  an  organic 
unit  of  monobionic  rank.  How  many  individual  lives  are  possible  in  the  life- 
history  of  a  species  we  at  present  do  not  know,  but  we  do  know  that  the  bionic 
value  of  the  species  (or,  strictly  speaking,  of  specific  characters)  is  of  an  entirely 
higher  order  than  that  of  the  individual.  To  be  more  concrete  the  individual,  the 
species,  the  genus,  etc. ,  constitute  organic  units  of  consecutively  higher  and  higher 
order  of  bionic  magnitude,  which  statement  may  be  tabulated  in  the  following 
way: 

Bionic  values  of  the  several  categories  of  classification  of  organisms. 

Individual : a  monobionic  unit. 

Species fc .  . ..  _  a  dibionic  unit. 

Genus a  tribionic  unit. 

Family a  tetrabionic  unit. 

Order a  pentabionic  unit. 

Class _ : a  sexbionic  unit. 

This  actual  dibion  may  be  compared  with  the  molecule  in  the 
atomic  theory,  for  the  theoretically  simplest  unit  of  the  series  (the 
monobion)  is  expressed  by  the  time  equivalent  of  an  individual  life 
from  germ  to  death — i.  e.,  the  life  period  of  the  individual. 

In  the  fossil  individual,  therefore,  we  find  no  evidence  of  the  time 
value  of  individual  development.  The  vigor  which  is  characteristic 
of  each  individual  of  the  species  at  the  time  may  be  expressed  by  the 
numbers  of  individual  fossils  found  buried  together  in  the  same  rock 
layer. 

Even  this  actual  number  of  specimens  in  a  rock  layer  is  not  a  cer- 
tain test  of  individual  characteristics  when  taken  alone,  because  the 
conditions  of  preservation,  we  must  believe,  very  greatly  modify  the 
number  of  individual  specimens  preserved  in  the  rocks.  In  order  to 
use  a  number  of  specimens  as  an  expression  of  bionic  value,  the  num- 
ber must  be  in  relation  to  the  number  of  other  species  preserved  at 
the  same  time  under  the  same  conditions.  It  is  the  relative  abun- 
dance or  rarity  of  a  species  in  the  local  faunule  list  alone  that  is  of 
value,  just  as  in  the  analysis  of  a  mineral  the  percentages  of  the  com- 
ponent elements  are  significant,  not  their  amount. 

So  far  as  fossils  are  concerned,  the  individual  is  recorded  only  by 
its  dead  remains,  and  the  number  of  individual  fossils  of  the  same 
kind  found  together  in  the  same  faunule  may  stand  for  a  measure  of 
the  bionic  value  of  that  kind  in  the  particular  aggregate  of  species 
making  up  the  faunule.  The  larger  the  number  of  individuals  the 
higher  the  bionic  value  of  the  species  relative  to  the  other  species  in 
the  combination.  Those  species,  therefore,  which  are  represented  by 
the  greater  number  of  individuals  in  a  faunule  constitute  I  he  dominant 
species  of  the  particular  faunule.  The  adjustment  of  equilibrium 
among  the  species  with  each  other  and  with  the  environmenl  is  such  a 
complex  and  delicate  matter  that  it  is  preserved  for  each  faunule  for 

Bull.  210— 03, 9 


130  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

a  brief  lapse  of  geological  time.  This  brief  time,  represented  by  the 
preservation  of  the  bionic  equilibrium  of  a  faunule  aggregate,  is  taken 
as  the  measure  of  the  unit  of  geological  time — the  hemera.  The  visi- 
ble expression  of  the  hemera  is  the  temporary  fa unule,  the  analysis 
of  which  into  its  constituent  species  constitutes  the  faunule  list  of  a 
particular  locality  (geographically)  and  particular  zone  (stratigraph- 
ically ) . 

For  the  purpose  of  ascertaining  the  bionic  value  of  fossils  it  is 
necessary  to  know  the  list  of  species  occurring  together  in  the  same 
faunule,  or  temporary  association  of  species,  and  the  abundance  or 
rarity  of  each  in  that  combination;  and  second,  it  is  necessary  to 
obtain  such  faunules  at  frequent  intervals  separate  from  one  another, 
in  order  to  ascertain  how  constant  is  the  appearance  of  the  species  in 
the  general  region  over  which  the  fauna  is  distributed. 

The  bionic  values  ma}'  be  expressed  mathematically  by  recording 
the  number  of  times  of  appearance.  These  will  then  stand  as  nume- 
rators of  fractions  of  which  the  denominator  is  the  total  number  of 
faunules  listed. 

When  the  faunules  are  from  the  same  formation,  but  from  sepa- 
rate stations,  the  statistics  will  show  the  frequenc}7  of  geographical 
distribution  of  the  species.  If  the  distribution  is  wide  and  general 
the  numerator  will  be  high,  if  the  species  is  local  in  distribution  the 
numerator  will  be  low.  The  place  of  the  species  in  the  general  fauna, 
based  on  such  estimate  of  its  bionic  value,  may  be  called  its  distribu- 
tion value,  by  which  will  be  meanl  the  power  of  the  species  to  spread 
itself  geographically  and  to  preserve  its  life  under  diverse  conditions 
of  environment. 

In  like  manner,  the  frequency  of  occurence  of  a  species  in  different 
faunules  found  at  successive  horizons  throughout  the  strata  of  a  single 
section  will  express  bionic  value  of  a  different  kind,  viz,  the  power  of 
the  species  to  reproduce  itself  and  maintain  its  place  in  the  midst  of 
the  competing  species  with  Avhich  it  lives.  This  may  be  called  its 
range  value.  It  will  be  expressed  by  a  high  figure  when  the  species 
appears  at  a  large  number  of  the  horizons  of  the  column  examined, 
and  when  it  is  of  rare  occurrence  in  such  faunules  its  numerator  will 
be  relatively  small. 

The  third  kind  of  bionic  value  will  be  expressed  by  the  abundance 
or  rarity  of  individuals  of  the  species  in  the  particular  fauna!  combi- 
nation of  each  faunule.     This  may  be  spoken  of  as  frequency  value. 

To  estimate  the  predominant  characteristics  of  the  fauna,  then, 
three  measures  of  bionic  values  for  each  species  may  be  summed  up, 
and  the  species  whose  bionic  values  of  these  three  kinds  (viz,  distribu- 
tion, range,  and  frequency  values)  reach  the  highest  total  average  will 
constitute  the  standard  dominant  list  of  species  of  the  particular  fauna. 

The  application  and  illustration  of  these  rules  are  given  in  the 
preceding  pages  of  this  bulletin. 


williams]  BIONIC    VALUE    OF    FOSSILS.  131 

REVISED    DEFINITIONS    OF    THE    TERMS    FAUNA  AND    FAUNULE. 

The  term  fauna  is  commonly  used  in  paleontology  to  indicate  the 
list  of  fossils  contained  in  a  single  formation,  but  it  is  important  to 
observe  that  the  limits  of  the  lithological  formation  do  not  determine 
the  limits  of  the  fauna.  It  will  be  seen  from  the  discussions  of  faunas 
and  faunules  in  this  paper  that  a  new  definition  of  a  fauna  is  require*  1 
which  shall  not  be  dependent  upon  formation  boundaries.  The  fol- 
lowing points  should  be  included  in  such  a  definition :  For  paleon- 
tology a  fauna  is  an  aggregate  of  local  and  temporary  faunules  in 
which  is  expressed  a  common,  corporate  aggregate  of  organic  species. 
The  corporate  nature  of  the  aggregation  is  indicated  by  the  relative 
bionic  values  maintained  b}~  the  species  in  the  faunal  aggregate. 
The  dominant  species  of  a  fauna  show  their  relation  to  the  fauna  by 
their  higher  bionic  values,  the  less  dominant  species  by  their  low 
bionic  value,  and  the  fauna  shows  its  integrity  by  maintaining  the 
normal  equilibrium  of  the  specific  aggregates.  The  Tropidolejitus 
carinatus  fauna  is  defined  in  this  report  as  an  example  of  such  a 
fauna. 

In  the  process  of  collecting  fossils  it  is  necessary  to  keep  separate 
records  of  the  specimens  taken  from  each  fossiliferous  stratum  of 
each  separate  outcrop.  The  group  of  specimens  from  such  a  unit 
stratum  (or  from  several  contiguous  strata  in  which  the  same  set  of 
species  are  distributed)  is  called  a  faunule.  It  is  a  sample  of  the 
general  fauna  of  the  formation,  coming  from  a  definite  horizon  in  the 
local  section  and  from  a  definite  geographical  position.  A  faunule  wi  1 1 
exhibit  the  local  and  temporary  aspects  of  the  fauna,  and  in  most 
cases  it  will  contain  only  a  small  part  of  the  species  which  properly 
belong  to  the  general  fauna.  The  faunule  may  be  regarded  as  closely 
ad justed  to  a  particular  set  of  environmental  conditions,  which, 
though  not  known,  may  be  to  some  degree  inferred  by  the  character  of 
the  sediment  in  wliich  it  is  found.  It  is  often  observed,  however, 
that  successive  faunules  in  a  column  of  strata  differ  greatly,  although 
very  slight  change  in  character  of  sediments  is  observed.  Living 
faunas  in  modern  ocean  waters  so  differ  on  account  of  differences  of 
temperature  or  other  conditions  of  the  water,  and  it  may  be  supposed 
that  such  differences  affected  in  a  similar  way  the  ancient  geological 
faunas. 

The  particular  part  of  the  formation,  be  it  a  single  stratum,  or  a 
few  or  many  feet  of  thickness  of  rock  throughout  which  the  faunule 
is  recognized  is  properly  a  zone,  as  defined  on  page  20;  and  the 
locality,  number,  and  name  may  be  applied  to  the  specimens  of  the 
faunule,  as  well  as  to  the  stratum  or  strata  from  which  they  came.  Bui 
the  faunule  is  the  faunule  of  such  a  zone,  and  its  proper  name  should 
be  derived  from  the  name  of  some  dominant  species  (as  Leiorhynchus 
globuliforme  faunule  or  Paracyclas  Virata  faunule)  when  the  analysis 


132  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

lias  been  made  and  the  character  of  the  faunule  has  been  fully  estab- 
lished. 

In  so  designating  the  faunule  the  distinction  between  fauna  and 
faunule  is  exhibited.  We  may  speak  of  a  Tropidoleptus  faunule  in 
the  Chemung  formation;  this  will  indicate  only  a  temporary  recur- 
rence of  the  species  and  its  associates  in  the  midst  of  the  Spirifer 
disjunctus  fauna.  In  this  case  the  species  are  not  supposed  to  have 
stopped  their  existence  when  we  pass  above  or  below  the  particular 
zone  in  which  they  occur.  On  the  other  hand,  when  the  term  Tropi- 
doleptus carinatus  fauna  is  used  the  term  includes  not  only  all  the 
species  normally  associated  with  Tropidoleptus  carinatus  in  its  dis- 
tributional metropolis,  but  all  the  adjustments  and  modifications 
through  which  the  fauna  passes  in  the  course  of  both  its  migrations 
and  its  geological  succession,  so  long  as  the  dominant  species,  includ- 
ing Tropidoleptus  carinatus,  live. 

A  fauna,  therefore,  may  be  modified  and  have  a  history,  and  its 
integrity  may  be  discriminated  by  a  set  of  dominant  species,  the 
fauna  preserving  its  integrity  and  identity  so  long  (in  succession) 
and  so  far  (in  distribution)  as  the  dominant  species  retain  their 
ascendency  among  their  associates.  On  the  other  hand,  a  faunule  is 
limited  to  a  single  set  of  conditions  and  to  a  locality  of  limited  extent, 
and  maj^  not  be  modified  in  composition  without  losing  its  identity. 

THE  BIONIC  TIME-SCALE. 

At  the  close  of  the  paper  a  in  which  this  subject  of  the  bionic  means 
of  measuring  geological  time  was  first  announced  I  gave  a  sample 
table  of  classification  and  nomenclature  constructed  on  this  basis  and 
stated  the  general  terms  to  be  used  in  constructing  such  a  time-scale. 
They  were  as  follows : b 

Terms  of  the  bionic  time-scale. 

Chron. — An  indefinite  division  of  geological  time. 

Geochron. — The  time  equivalent  of  a  formation. 

Biochron. — The  time  equivalent  of  a  fauna  or  flora. 

Hemera. — The  technical  name  for  a  monobiochron ,  indicated  by  the  preserva- 
tion of  the  individual  characteristics  of  all  the  species  of  a  local  faunule,  as  shown 
by  the  association  in  the  rocks  of  the  same  species  in  the  same  relative  abundance, 
size,  and  vigor.  An  example  is  the  hemera  of  Rhynchonella  {Hypothyris) 
cuboicles. 

Epoch. — The  name  of  a  dibiochron,  indicating  the  time  equivalent  of  the  endur- 
ance of  a  particular  species  and  of  the  integrity  of  the  fauna  of  which  it  is  the 
dominant  characteristic.  An  example  is  the  Tropidoleptus  carinatus  epoch,  which 
corresponds  closely  to  the  limits  of  the  Hamilton  formation  of  eastern  New  York. 

Period. — May  be  defined  as  a  tribiochron.  This  is  the  time  equivalent  of  the 
continuance  of  a  genus.  An  example  is  the  Paradoxides  period,  which  corre- 
sponds to  the  Acadian  formation  of  the  Cambrian  system. 

aThe  discrimination  of  time  values  in  geology:  Jour.  Geol.,  Vol.  IX,  1901,  pp.  570-585. 
&Loc.  cit.,  pp  583-584. 


WILLIAMS. 


BIONIC    VALUE    OF    FOSSILS. 


133 


Era.— May  be  used  to  indicate  a  tetrabioehron;  and  Olenide  era  would  indicate 
the  life  range  of  the  family  Olenidce,  corresponding  in  length,  approximately,  to 
the  geochron  of  the  Cambrian  system,  though  not  strictly  so. 

Eon. — May  stand  as  the  name  for  a  pentabiochron;  an  example  of  which  is  the 
Trilobit e  eon,  the  time  equivalent  of  the  continuance  of  the  order,  or  subclass, 
Trilobita,  which  closely  approximates  the  length  of  the  Paleozoic  geochron. 


Classification  and  nomenclature  of  the  Trilobite  eon  (Paleozoic)  on   the 
the  bionic  values  of  fossils. 


of 


Eon. 

Period. 

Epo<-k. 

Formational  equivalent 
(approximate). 

• 

f  Cameratus 

Coal  Measures. 

«, 

Phillipsian 

Increbescens 

Kaskaskia,  St.  Louis. 

Logani  _ .  _•  _  _ 

Keokuk.  Burlington. 
Kinderhook. 

Marionensis 

Disjunctus 

Chemung. 

Mucronatus 

Hamilton. 

6. 

Phacopsian 

Acuminatus 

Corniferous. 

Trilobite 

Arenosus 

Macropleurus 

Oriskany. 

Lower  Helderberg 

Calymenean 

/  Vanuxemi 

1  Radiatus 

Waterlime,  etc. 

.1. 

Niagara,  etc. 

4. 

Asaphian 

(?) 

Ordovician. 

3. 

Olenian  

) 

2_ 

Paradoxidean 

(?) 

Cambrian. 

U- 

Olenellian 

Upon  reviewing  the  subject  I  am  of  the  opinion  that  this  table 
fairly  expresses  the  difficulties  to  be  encountered  in  applying  the 
principles  here  set  forth  as  well  as  the  advantages.  When  the 
table  was  constructed  the  details  of  the  present  paper  were  not 
ready  for  presentation.  I  am  able  now  to  point  out  the  method  of 
application  to  the  Devonian  faunas  which  have  been  already  sub- 
jected to  analysis. 

The  several  faunas  under  consideration  are  the  measures  of  epochs 
according  to  this  scheme.  We  have  thus:  Tropidoleptus  carinatus 
epoch,  Glyptocardia  speciosa  epoch,  Prod  urf  din  speciosa  epoch,  Spiri- 
fe  i -  d isj u  net  us  epoch . 

Regarding  these  faunas  and  the  time  epochs  indicated  by  them,  it 
has  been  demonstrated  that  the  range  of  time  indicated  by  each  epoch 
is  not  restricted  to  the  particular  formational  limits  in  which  the  fauna 
is  typically  confined. 

The  Tropidoleptus  epoch  laps  over  both  of  the  following  two  and 
reaches  to  the  beginning  of  the  fourth.  The  epoch  of  I  he  Glyptocardia 
speciosa  fauna  is  prior  to  and  follows  the  limits  marked  by  the  typical 
Productella  speciosa  fauna  at  Ithaca. 

The  Spirifer  disjunctus  fauna,  though  in  general  Later  than  the 
other  three  faunas  in  the  New  York  province,  probably  dates  its 
origin  from  a  much  earlier  stage  outside  that  province,  into  which  it 
most  probably  came  by  migration,  and  not  as  an  evolution  from  the 
earlier  inhabitants  of  the  New  York  province. 


134  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

We  have  thus  demonstrated  the  lapping  of  the  faunas.  '  This  is  a 
perfectly  legitimate  conclusion  on  the  presumption  that  each  of  the 
faunas  is  not  the  universally  distributed  marine  life  of  a  particular 
epoch,  but  the  fauna  of  a  particular  environment  of  that  epoch.  We 
are  perfectly  familiar  with  this  discordance  in  the  limits  of  dynasties 
of  different  races  of  peoples  in  human  history. 

The  facts  have  also  shown  that  migration — not  of  single  species, 
but  of  the  whole  fauna,  a  shifting  of  the  metropolis  with  the  limits  of 
distribution  of  the  fauna  as  a  corporate  whole — has  taken  place. 

This  has  been  expressed  in  relation  to  formations  by  a  transgression 
of  one  fauna  over  another,  thus  calling  for  the  assumption  that  the 
limits  of  a  formation  based  upon  sudden  change  in  the  fossil  contents 
can  not  be  regarded  as  synchronous  for  two  parts  of  even  the  same 
province  and,  wherever  they  are  thus  sudden  and  sharp,  can  not  be 
synchronous  with  the  limits  of  either  the  earlier  or  later  fauna  in 
evidence. 

Nevertheless,  with  all  this  lapping,  shifting,  and  incomplete  expres- 
sion of  the  faunas,  the  statistics  also  demonstrate  the  intrinsic  value 
of  fossils  for  measuring  and  indicating  time.  The  sediments,  whether 
by  their  lithological  constitution,  their  structural  form,  or  their  strati- 
graphical  position,  furnish  no  such  positive  evidence  of  points  or 
durations  of  geological  time. 

The  bionic  method  of  measurement  of  time  relations,  though  in  the 
present  state  of  knowledge  it  can  not  be  used  as  a  substitute  for  the 
more  apparent  structure  scale,  will  serve  to  make  the  imperfections 
of  the  present  methods  apparent.  Our  ignorance  of  the  actual  as 
well  as  relative  life  periods  of  the  great  majority  of  species  of  paleon- 
tology makes  it  impossible  to  reduce  life  periods  to  actual  years  or 
centuries. 

It  is  also  to  be  said  that  for  the  practical  purposes  of  geological 
mapping  and  the  descriptions  of  geological  structure  the  formations 
are  the  essential  elements,  and  a  chronological  classification  of  them 
is  a  convenient  rather  than  an  essential  one. 

Nevertheless,  whenever  the  attempt  is  made  to  become  accurate  in 
establishing  time  equivalencies  or  correlations,  it  is  in  this  direction 
we  must  turn.  The  collection  of  statistics  along  the  lines  here  pro- 
posed will  facilitate  the  formation  of  a  definite  time-scale  for  geology. 

It  is  by  making  our  knowledge  of  the  composition,  the  range,  and 
the  geographical  distribution  of  fossil  faunas  more  complete  and  more 
exact  that  our  classification  and  correlation  of  geological  formations 
is  to  be  perfected. 

At  present  we  know  too  little  about  fossil  faunas  to  be  able  to  pre- 
dict in  what  manner  their  actual  time  limits  will  be  defined  or  dis- 
criminated, but  enough  light  has  already  been  thrown  upon  the 
matter  to  show  that  it  will  be  by  means  of  the  history  which  organ- 
isms have  expressed  in  their  continuous  life  and  evolution  that  we 
may  expect  ultimately  to  mark  off  the  stages  of  geological  time. 


B  I  BL  I  OGRA  PH  Y. 

In  the  preparation  of  this  report  a  large  number  of  general  as  well 
as  special  papers  have  been  consulted  which  do  not  require  special 
mention.  A  shorter  list  of  papers  furnishes  a  great  pail  of  the  statis- 
tics herein  elaborat  ed  and  discussed.  To  this  list  the  reader  is  referred 
for  details  and  particulars,  and  for  authority  for  facts  which  arc  made 
use  of  in  the  present  discussion  of  the  Devonian  faunas. 

Beecher,  C.  E.,  Hall,  J.  W.,  Hall,  C.  E.     Note  on   the  Oneonta   sandstone  in 
the  vicinity  of  Oxford,  Chenango  Comity,  New  York. 
Fifth  Ann.  Rept.  State  Geologist  of  New  York,  1886,  p.  11. 

Calvin,  S.     On  the  fauna  found  at  Lime  Creek.  Iowa,  and  its  relation  to  other 
geological  faunas. 

Am.  Jour.  Sci.,  3d  series,  vol.  25, 1883,  pp.  432-436. 

Chamberlin,  T.  C.     A  group  of  hypotheses  hearing  on  climatic  changes. 
Jour.  Geol.,  vol.  •">,  1897,  pp.  653-683. 

The  ulterior  basis  of  time  divisions  and   the  classification  of  geologic 

history. 
Jour.  Geol.,  vol.  6,  1898,  pp.  449-462,  3  figs. 

A  systematic  source  of  evolution  of  provincial  faunas. 

Jour.  Geol.,  vol.  6,  1898,  pp.  597-608. 

The  influence  of  great  epochs  of  limestone  formation  upon  the  constitu- 


tion of  the  atmosphere. 
Jour.  Geol.,  vol.  6,  1898,  pp.  6(19-621. 
Clarke,  J.  M.     A  brief  outline  of  the  geological  succession  in  Ontario  County, 
New  York,  to  accompany  a  map. 
Fourth  Ann.  Rept.  State  Geologist  of  New  York.  L885,  pp  2-  22,  map. 

On  the  higher  Devonian  faunas  of  Ontario  County.  New  York. 

Bull.  U.S.  Geol.  Survey  No.  16,  1885,  pp.  1-86,  pis.  i-iii. 

The  Hercynian  question. 

Eighth  Ann.  Rept,  State  Geologist  of  New  York,  L889,  pp.  62  -91. 

A  list  of  the  species  constituting  the  known  fauna  and  flora  of  the  Mar- 

cellus  epoch  in  New  York. 

Eighth  Ann.  Rept  State  Geologist  of  New  York.  1889,  pp.  60  61. 

The  fauna  with  Goniatites  intumescens  Beyrich. 

Am.  Geol.,  vol.  8,  1891,  pp.  86-105. 

Die  Fauna  mit  Goniatites  intumescens  im  westlichen  New  York. 

Neues  Jahrb.  fur  Mm,  Band  I,  1891,  pp.  L61   186. 

The  "  Here y n -f rage  "  and  the  Helderberg  limestones  in  North  America. 

Am.  Geol.,  vol.  7,  1891,  pp.  109-113. 

The  discovery  of  Clymenia  in  the  fauna  of  the  Intumescens  zone  i  Naples 

beds)  of  western  New  York  and  its  geological  significance. 

Am.  Jour.  Sci..  3d  series,  vol.  4-1  lw>ri,  pp  57  64,  plate. 

The  succession  of  the  fossil  faunas  in  the  section  of  the  Livonia  sail  shaft. 


Thirteenth  Ann.  Rept,  State  Geologist  of  New  York.  vol.  1.  Geology,  L893,  pp.  131   158 
—    The  stratigraphic  and  faunal  relations  of  the  Oneonta  sandstones  mid 
shales,  the  Ithaca  and  Portage  groups  in  central  New  York. 

Fifteenth  Ann.  Rept.  State  Geologist  of  New  York,  Albany,  I89Z,  pp,  :.''.  81 

135 


136  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

Cleland,  H.  F.     A  study  of  the  fossil  faunas  in  the  Hamilton  stage  of  New  York. 

Bull.  U.  S.  Geol.  Survey  No.  206.  1902. 
Darton,  N.  H.     On  the  area   of   Upper  Silurian  rocks  near   Cornwall  station, 

eastern-central  Orange  County,  New  York. 

Am.  Jour.  Sci.,  3d  series,  vol  31, 1886,  pp  209-216. 
On  two  overthrusts  in  eastern  New  York. 

Bull.  Geol.  Soc  Am.,  vol.  4,  1893,  pp  436-439. 
The  strati  graphic  relations  of  the  Oneonta  and  Chemung  formations  in 

eastern-central  New  York. 

Am.  Jour.  Sci.,  3d  series,  vol.  45,1893,  pp.  203-209. 

Notes  on  the  stratigraphy  of  a  portion  of  central  Appalachian  Virginia. 

Am.  Geol.,  vol.  10,  1892,  pp.  10-18. 

Shawangunk  Mountain. 

Nat,  Geog.  Mag.,  vol.  6,  1894,  pp.  23-34,  pis.  1-3,  figs.  1-3. 

Report  on  the  relations  of  the  Helderberg  limestones  and  associated  for- 


mations in  eastern  New  York. 
Forty-seventh  Ann.  Rept.  New  York  State  Museum,  1894,  pp.  3;  3-422,  1-4,  figs.  1-5 

Preliminary  report  on  the  geology  of  Albany  County,  New  York. 


Forty-seventh  Ann  Rept.  New  York  State  Museum,  1894,  pp.  425-455,  pis.  1-6,  figs.  1-9. 

Preliminary  report  on  the  geology  of  Ulster  County,  New  York. 

Forty-seventh  Ann.  Rept.  New  York  State  Museum,  1894,  pp.  485-566,  pis.  1-23,  figs.  1-18. 

Geologic  relations  from  Green  Pond.  New  Jersey,  to  Skunnemunk  Moun- 
tain. New  York. 
Bull.  Geol.  Soc.  Am.,  vol  5.  1894,  pp.  367-394,  pi.  IT. 

Fairchild,  H.  L.     A  section  of  the  strata  at  Rochester.  N.  Y.,  as  shown  by  a  deep 
boring. 

Proc.  Rochester  Acad.  Sci.,  vol.  1.  L891,  pp.  182-186. 

Fletcher,  H.     Geological  nomenclature  in  Nova  Scotia. 
Trans.  Nova  Scotia  lust.  Sci  ,  vol.  10,  1900,  pp.  535-244. 

Grabau,  A.  W.     The  faunas  of  the  Hamilton  group  of  Eighteenmile  Creek  and 
vicinity  in  western  New  York. 
Sixteenth  Ann.  Rept.  State  Geologist  of  New  York,  1898,  pp.  233-33«t 

The  geology  of  Eighteenmile  Creek. 

Bull.  Buffalo  Soc.  Nat.  Science,  vol.  6,  no.  1,  1898,  pp.  1-91. 

The  paleontology  of  Eighteenmile  Creek  and  the  lake  shore  sections  of 


Erie  County,  New  York. 
Bull.  Buffalo  Soc.  Nat.  Science,  vol,  6,  nos.  2,  3,  4,  1899,  pp.  91-403. 

Hall,  James.     Note  on  the  intimate  relations  of  the  Chemung  group  and  Waverly 
sandstone  in  northwestern  Pennsylvania  and  southwestern  New  York. 
Proc.  Am.  Assoc  Adv.  Sci.,  vol.  33,  1885.  pp.  416-419. 

On  the  genus  Spirifera  and  its  interrelations  with  the  genera  Spiriferiyia, 

Syringothyris,  Cyrtia,  &ndCyrtii<a. 

Bull.  Geol.  Soc.  Am.,  vol,  1,  1890,  pp.  567  568. 

Harris,  G.  D.     Notes  on  the  geology  of  southwestern  New  York. 

Am.  Geol.,  vol.  7,  1891.  pp.  164-178,  pi.  4. 

Honeyman,  D.     On  the  geology  of  Arisaig,  Nova  Scotia. 

Quart.  Jour.  Geol.  Soc.  November,  1864,  pp.  33:3-345. 
Kindle,  E.  M.     The  relation  of  the  fauna  of  the  Ithaca  group  to  the  faunas  of 

the  Portage  and  Chemung. 

Bull.  Am.  Paleont.,  vol.  2,  No.  6,  December  25,  1896,  pp.  1-56. 

The  Devonian  and  Lower  Carboniferous  faunas  of  southern  Indiana  and 

central  Kentucky. 

Bull.  Am.  Paleont.,  vol.  3.  No.  12,  June  5,  1899,  pp.  1-111. 


BIBLIOGRAPHY.  137 

Marcou,  Jules.     Some  remarks  on  Prof.  Henry  S.  Williams's  report  of  the  sub- 
committee on  the  Upper  Palaeozoic  (Devonic). 
Am.  Geol.,  vol  2,  1889,  pp.  60-61. 

Miller,  S.  A.  North  American  Mesozoic  and  Cenozoic  Geology  and  Paleon- 
tology.    (And  supplements.)  1889-1897. 

Prosser,  C.  S.  Section  of  the  Lower  Devonian  and  Upper  Silurian  strata  of  cen- 
tral New  York  as  shown  by  deep  well  at  Morrisville. 

Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  36,  1888,  pp.  208-309. 

The  Uppei  Hamilton  of  Chenango  and  Otsego  counties.  New  York. 

Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  36.  1888,  p.  210. 

The  classification  and  distribution  of  the  Hamilton  and  Chemung  series 

of  central  and  eastern  New  York.     Part  II. 

Seventeenth  Ann.  Rept.  State  Geologist  of  New  York,  1900,  pp.  67-327. 

The.  thickness  of  the   Devonian   and  Silurian  rocks  in  western-central 

New  York. 

Am.  Geol.,  vol.  6,  1890,  pp.  199-211. 

The  geological  position  of  the  Catskill  group. 

Am.  Geol.,  vol.  7,  1891,  pp.  351-366. 

Notes  on  the  geology  of  Skunneinunk  Mountain.  ( )range  County,  N.  Y. 

Trans.  New  York  Acafl.  Sci.,  vol.  11,  1892,  pp.  132-119. 

The  thickness  of  the  Devonian  and  Silurian  rocks  of  western  New  York, 


approximately  along  the  line  of  the  Genesee  River. 
Proc.  Rochester  Acad.  Sci.,  vol.  2,  1892,  pp.  49-101. 

—  The  Devonian  system  of  eastern  Pennsylvania. 
Am.  Jour.  Sci.,  3d  series,  vol.  44,  1892,  pp.  210-221. 

—  The  thickness  of  the  Devonian  and  Silurian  rocks  of  central  New  York. 
Bull.  Geol.  Soc.  Am.,  vol.  4,  1893,  pp.  91-118. 

—  The  Devonian  section  of  central  New  York,  along  the  LTnadilla  River. 
Forty-sixth  Ann.  Rept.  New  York  State  Museum,  1893,  pp.  256-288. 

—  The  Devonian  system  of  eastern  Pennsylvania  and  New  York. 
Bull.  U.  S.  Geol.  Survey  No.  120, 1894,  pp.  1-81. 

—  The  classification  and  distribution  of  the  Hamilton  and  Chemung  series 


of  central  and  eastern  New  York.     Part  I. 
Fifteenth  Ann.  Rept.  State  Geologist  of  New  York,  1895,  pp.  81!  225. 
Schuchert,  Charles.     A  list  of  the  fossils  occurring  in  the  Oriskany  sandstone 
of  Maryland,  New  York,  and  Ontario. 
Eighth  Ann.  Rept.  State  Geologist,  1889,  pp.  50-54. 

A  synopsis  of  American  fossil  Brachiopoda,  including  bibliography  and 

synonymy. 

Bull.  U.  S.  Geol.  Survey  No.  87,  1897,  pp.  1-461. 

Lower  Devonic  aspect  of  the  Lower  Helderberg  and  Oriskany  formations. 


Bull.  Geol.  Soc.  Am.,  vol.  11, 1900,  pp.  241-a32. 
Sherzer,  W.  H.     Geological  report  on  Monroe  County.  Mich. 

Geol.  Surv.  Michigan,  vol.  7,  part  1,  pp.  1-240,  pis.  xvii,  8  figures,  including  :>  colored  maps. 
Stevenson,  J.  J.     The  Chemung  and  Catskill  (Upper  Devonian!  on  the  eastern 

side  of  the  Appalachian  basin. 

Am.  Geol..  vol.  9.  1892,  pp.  6-34. 
Teller,  E.  E.,  and  Monroe,  C.  S.     The  fauna  of  the  Devonian  formation  at  Mil- 
waukee, Wis. 

Jour.  Geol.,  vol.  7,  1899,  pp.  272-283. 


138  CORRELATION    OF    GEOLOGICAL    FAUNAS.  [bull.  210. 

Weller,  Stuart.     The  succession  of  fossil  faunas  at  Springfield.  Mo. 
Am.  Join-.  Sci.,  3d  series,  vol.  49,  1895,  pp.  185-199. 

A  circum-insular  Paleozoic  fauna. 

Jour.  Geol.,  vol.  3,  1895,  pp.  903-917. 

Correlation  of  the  Devonian  faunas  in  southern  Illinois. 

Jour.  Geol.,  vol.  5,  1897,  pp.  625-6a5. 

Classification  of  Mississippian  series. 

Jour.  Geol.,  vol.  0.  1898,  pp.  303-314. 

The  Silurian  fauna  interpreted  on  the  epicontinental  basis. 

Jour.  Geol.,  vol.  6,  1898,  pp.  692-703. 

A  preliminary  report  on  the  stratigraphic  paleontology  of  Walpack  Ridge, 
in  Sussex  County,  N.  J. 
Ann.  Rept.  State  Geologist  New  Jersey  for  1899,  19! hi.  pp.  1-53. 

The  succession  of  fossil  faunas  in  the  Kinderhook  beds  at  Burlington,  Iowa. 


Iowa  Geol.  Surv..  vol.  10,  1900,  pp.  6:3-79. 
—    Correlation  of  the  Kinderhook  formations  of  southwestern  Missouri. 


Jour.  Geol..  vol.  9.  1901,  pp.  130-H8. 

Williams,  H.  S.     The  life  history  of  Spirifer  Icevis  Hall:  a  paleontological  study. 
Ann.  New  York  Acad.  Sci..  vol.  2.  pp.  140  L60,  pi.  xiv. 

The  recurrence  of  faunas  in  the  Devonian  rocks  of  New  York. 

Proc.  Am.  Assoc  Adv.  Sci..  vol.  30,  1882,  pp.  1st;  190. 

Catalogue  of  the  fossils  of  the  Chemung  period  of  North  America. 
14  pp.,  Ithaca,  N.  Y. 

On  a  remarkable  fauna  at  the  base  of  the  Chemung  group  in  New  York. 

Am.  Jour.  Sci.,  3d  series,  vol.  25,  1883,  pp.  97-104. 

Equivalency  of  the  Lime  Creek  beds  of  Iowa. 

Am.  Jour.  Sci..  3d  series,  vol.  25, 1883,  p.  311. 

The  undulations  of  the  rock  masses  across  central  New  York  State. 
Proc.  Am.  Assoc  Adv.  Sci..  vol.  31,  1883.  p.  412. 

On  the  fossil  faunas  of  the  Upper  Devonian,  along  the  meridian  of  76°  30', 

from  Tompkins  County,  N.  Y.,  to  Bradford  County.  Pa. 

Bull.  U   S.  Geol.  Survey  No.  3,  pp.  1  36. 

Geographical  and  physical  conditions  as  modifying  fossil  faunas. 

Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  33,  1885,  pp.  422-423. 

On  the  classification  of  the  Upper  Devonian. 


Proc.  Am.  Assoc.  Adv.  Sci..  vol.  :;4.  L886,  pp.  222-234. 

On  the  fossil  faunas  of  the  Upper  Devonian — the  Genesee  section,  New 
York. 
Bull.  U.  S.  Geol.  Survey  No.  41,  pp.  1-121,  pis.  i-iv. 

—  The  Strophomenida?;  a  paleontological  study  of  the  method  of  initiation 
of  genera  and  species. 

Proc.  Am.  Assoc.  Adv.  Sci..  vol.  35,  1887,  p.  227, 

—  On  the  different  types  of  the  Devonian  in  North  America. 
Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  36, 1888,  p.  207. 

—  On  the  different  types  of  the  Devonian  system  in  North  America. 
Am.  Jour.  Sci.,  3d  series,  vol.  35, 1888,  pp.  51-59. 

—  Report  of  the  subcommittee  on  the  Upper  Paleozoic  (Devonic).     Inter- 
national Congress  of  Geologists. 

Philadelphia,  1888,  pp.  cl-c31, 

—  On  the  relations  of  the  Devonian  faunas  of  Iowa. 

Am.  Geol.,  vol.  3,  1889,  pp.  230-2a3. 


BIBLIOGEAPHY.  139 

"Williams,  H.  S.     The  Cuboides  zone  and  its  fauna;  a  discussion  of  methods  of 
correlation. 
Bull.  Geol.  Soc.  Am.,  vol.  1,  1890,  pp.  481-501,  pis.  xi-xiii. 

Correlation  paper,  Devonian  and  Carboniferous. 

Bull.  U.  S.  Geol.  Survey  No.  80,  1891,  pp.  1-275). 

The  scope  of  paleontology  and  its  value  to  geologists. 


Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  41,  1892,  pp.  149-170.    Ara.  Geol.,  vol.  10,  1892,  pp.  148-169. 

—  Dual  nomenclature  in  geological  classification. 
Jour.  Geol.,  vol.  2,  pp.  145-160. 

—  On  the  origin  of  the  Chouteau  fauna. 
Jour.  Geol.,  vol.  4,  1896,  pp.  283-290. 

—  On  the  Southern  Devonian  formations. 
Am.  Jour.  Sci.,  vol.  3,  1897,  pp.  393-404. 

—  The  Silurian-Devonian  boundary  in  North  America. 


Bull.  Geol.  Soc.  Am.,  vol.  11,  19(H),  pp.  333-346. 

The  Silurian-Devonian  boundary  in  North  America.     I.  The  Chapman 

sandstone  fauna.  % 

Am.  Jour.  Sci.,  4th  series,  vol.  9,  1900,  pp.  203-213. 

Williams,  H.  S.  and  Gregory,  H.  E.     Contributions  to  the  geology  of  Maine. 
Bull.  U.  S.  Geol.  Survey  No.  165,  1900,  pp.  1-203. 

Williams,  S.  G.     The  westward  extension  of  rocks  of  Lower  Helderberg  age  in 
New  York. 
Am.  Jour.  Sci.,  3d  series,  vol.  31,  1886,  pp.  139-145. 

Note  on  the  Lower  Helderberg  rocks  of  Cayuga  Lake. 

Sixth  Ann.  Rept.  State  Geologist  of  New  York,  1887,  pp.  10-12. 

The  Tully  limestone,  its  distribution  and  its  known  fossils. 

Sixth  Ann.  Rept.  State  Geologist  of  New  York,  pp  13-29. 

The  Tully  limestone,  its  distribution,  its  irregularities,  its  character,  and 

its  life. 

Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  35,  1887.  p.  214. 

A  revision  of  the  Cayuga  Lake  section  of  the  Devonian. 

Proc.  Am.  Assoc.  Adv.  Sci.,  vol.  35,  1887,  p.  215. 


INDEX. 


Page. 

Actinopteria  boydi,  occurrence  of 72, 74, 76, 77 

Actinopteria  decussata,  occurrence  of 64 

Actinopteria  perstrialis,  occurrence  of 77, 78 

Actinopteria  theta,  occurrence  of 77 

Ambocoelia  gregaria,  occurrence  of 83, 86 

Ambocoelia  umbonata,  occurrence  of 51, 

56, 57,  59,  60, 61, 62, 63, 64, 69,  70, 
74,  75,  85,  86, 87, 88, 90, 91, 92, 95 
American  Association  for  the  Advancement 

of  Science,  report  made  before 8 

Amnigenia,  occurrence  of Ill 

Amnigenia  catskillensis,  geologic  horizon 

of 48 

Animal  and  plant  aggregates,  discussion  of.  13-20 

Athyris  angelica,  occurrence  of 85, 86, 87 

Athyris  angelica  stage  or  faunule,  geologic 

place  of 46, 48 

Athyris  polita,  occurrence  of 86 

Athyris  spiriferoides,  occurrence  of 51, 

56, 57,  59, 60,  61, 62, 63, 64, 65,  75 

Atrypa  globuliformis,  occurrence  of 98 

Atrypa  hystrix,  occurrence  of 79 

Atrypa  reticularis,  occurrence  of 74, 79, 95 

Atrypa  reticularis  stage  or  faunule,  geologic 

place  of 47 

Atrypa  spinosa  hystrix,  occurrence  of 83, 86 

Aviculopecten,  occurrence  of 90 

Barclay  coal  fauna,  geologic  place  of 47 

Barrande's  theory  of  "colonies,"  observa- 
tions on 31, 34 

Bedford  shale  stage  or  faunule,    geologic 

place  of 48 

Beecher,  C.  E.,  aid  by 49 

Bellerophon  leda,  occurrence  of 64 

Bellerophon  msera,  occurrence  of 96 

Benthos,  definition  of 14 

Berea  grit,  faunule  of 48 

Bibliography 135-139 

Biochron,  definition  of 31, 132 

Bion,  definition  of 127 

Bionic  classification,  scheme  of 30 

Bioriic  energy,  definition  of 127 

Bionic  equilibrium  of  a  fauna,  definition  of.        26 

Bionic  quality,  definition  of •     128 

Bionic  time-scale,  terms  of 132 

Bionic  value  of  fossils,  discussion  of 124-134 

table  showing 129 

Black  shales,  conditions  of  deposition  of. . .      110 

faunas  of 47, 48, 110 

st ratigraphic  equivalents  of 99 

Black  shales  fauna,  geologic  place  of 47 

stages  or  faunules  of 47 

Botanical  classification,  principles  of 15-16 


C. 

Page. 
Camarotoechia.     See  also  Rhynchonella. 
Camarotoechia  alleghania,  occurrence  of  . .        88 

Camarotoechia  contracta,  occurrence  of 83, 

85, 86;  87, 88, 91, 94, 96 
Camarotcechia  contracta   saxatilis,   occur- 
rence of 79 

Camarotcechia  duplicata,  occurrence  of 86 

Camarotoechia  eximia,  occurrence  of 74, 

76,  77, 88, 96 
Camarotoechia  orbicularis,  occurrence  of  . .  88 
Camarotoechia  cf.  prolifica,  occurrence  of. .    .    90 

Camarotcechia  sappho,  occurrence  of 88 

Camarotcechia  stephani,  occurrence  of 74, 

76,  77, 88, 95, 96 
Canada,  Hamilton  formation  in,  fauna  of. .  64-65 

Cardiola  speciosa,  occurrence  of 69 

Cardiola  speciosa  fauna,  correlation  of 45, 

46,48,81,82 

mutation  of 81, 82 

occurrence  of 69, 115 

stratigraphic  horizon  of 45, 46, 48, 81, 82, 99 

Catskill  fauna,  formations  containing 48 

geologic  place  of 45 

Catskill  flora,  geologic  place  of 47 

Catskill  formation,  fauna  of 48 

faunal  shifting  coincident  with  depo- 
sition of 116 

geologic  horizon  of,  local  variation  of. .      108 

stratigraphic  place  of 44, 47, 104, 120, 122 

Cayuga  Lake  section,  fauna  of 54-57, 73 

Cemetery  Hill,  Owego,  N.  Y.,  fossils  from..        90 
Centronella  julia  fauna,  geologic  place  of. .        46 

Chemung  fauna,  dominant  list  of 96 

faunules  of 48 

geologic  place  of 45 

mingling  of,  with  Ithaca  fauna 100 

table  showing 94 

Chemung  formation,  fauna  of 48, 

49, 50, 82-89,  95, 96 
fauna  of,  identity  of,  in  part,  with  that 

of  Hamilton  formation 38 

stratigraphic  place  of 43, 

44,47,99,112,120,122 

thickness  of 45, 93 

Chemung  (Upper)  zone,  fossils  of 88, 89 

Chenango  Valley,  New  York,   formations 

in,  thickness  of 93 

Chonetes  coronatus,  occurrence  of 51, 

56, 58, 59, 60, 62, 63, 64,  65,  75 

Chonetes  lepidus,  occurrence  of 57, 58, 64, 90 

Chonetes  mucronatus,  occurrence  of 56 

Chonetes  scitulus,  occurrence  of 57, 

58,  62,  63,  64,  74,  76, 85,  86,  87,  92, 95 
Chonetes  setigerus,  occurrence  of. .  72, 76, 90, 95, 96 
Chonetes  yandellanus,  occurrence  of 67 

141 


142 


INDEX. 


Page. 

Chron,  definition  of  term "...  31, 132 

Chronologic  terms,  bionic,  proposal  of 31 

Cladochonus  fauna,  geologic  place  of 45 

Clarke,  J.  M.,  aid  by 49 

cited  on  Chemung  and  Ithaca  forma- 
tions, limits  of 93 

cited  on  fauna  of  High  Point,  Naples, 

N.  Y 78,79 

cited  on  faunas  of  Livonia  salt  shaft ...        63 
cited  on  faunas  of  Portage  formation  at 

different  points 103 

cited  on  fossils  from  Juliand  Hill,  Che- 
nango County,  New  York 94 

cited  on  mingling  of  species  of  adjacent 

faunas 103 

cited  on  Oneonta  and  Portage   sand- 
stones, stratigraphic  equivalency  of. .      100 

work  done  by 8 

Clark,  W.  B.,  aid  by 67 

work  in  geologic  correlation  done  by  . .        10 

Cleland,  H.  F.,  aid  by 9, 49,  5 1  55 

cited  on    Hamilton  fauna  of    Cayuga 

Lake 80 

Cleveland  shale,  stratigraphic  place  of 47 

Coleolus  acicula,  occurrence  of 77, 90 

Coleolus  tenuicinctum,  occurrence  of 95 

Cornell  University,  work  done  at . . .  6, 7, 8, 9, 43, 46 
Correlation,  geologic,  diverse  data  employed 

for 117-120 

importance  of 10 

work  done  in 10 

Correlation  and  mutation  of   faunas,  dis- 
cussion of 81-82 

Cryphaeus  boothi,  occurrence  of 56,57,58,64 

Cryptonella  fauna,  geologic  place  of 45 

Cryptonella  eudora,  occurrence  of 77,78 

Cuboides  fauna,  occurrence  of 69 

results  of  studies  of 79 

Cuyahoga  -hale  and  sandstone,  faunule  of.        48 
Cypricardella  bellistriata.  occurrence  of  ...       74, 

77, 82,  90, 91, 95 
Cypricardella  complanata,  occurrence  of  . .  95 
Cypricardella  gregaria,  occurrence  of.  76, 77. 95, 96 
Cyrtia.    See  Spirifer  altus. 

Cyrtina  hamiltonensis,  occurrence  of .. .  74,91,95 
Cystiphyllum,  occurrence  of 67 


Dall,  W.  H.,  and    Harris,  G.  I).,  work    in 

geologic  correlation  done  by 10 

Dalmanella  infera,  occurrence  of 79 

Dalmanella  leonensis,  occurrence  of 86 

Darton,  N.  H.,  aid  by 8,49 

Dana,  J.  D.,  cited 43 

Darwin,  Charles,  cited 33, 41 

Delaware  limestone,  stratigraphic  equiva- 
lents of 122 

Delthyris  mesicostalis,  occurrence  of 61, 

70,  72, 83, 85, 86, 88, 91, 94, 95, 96 
See  alto  Spirifer  mesicostalis. 
Devonian  formations,  dissection  and  analy- 
sis of  faunas  of 42-96 

Devonian  formations   of   Ohio   and    New 

York,  correlation  of 120-123 

Devonian  limestone,  intermediate  faunas 

of 7 


Page. 
Devonian  system,  faunal  classification  of, 

introduction  of 45-48 

Dewalque,  G.,  cited 28 

Diaphorostoma  lineatum,  occurrence  of 64 

Discina  fauna,  geologic  place  of 45 

Disjunctus  fauna.    See  Spirifer  disjunctus. 
Distribution,  geographic,  of  faunas,  obser- 
vations on 16-20 

I »ual  nomenclature  in  geology,  suggestions 

concerning 11-13 

title  of  paper  on 12 

Ectenodesma  birostratum,  occurrence  of . .        96 

Edmondia  philipi,  occurrence  of 96 

Eighreenmile  Creek  section,  fauna  of 57-58 

Encrinal  beds,  geologic  place  of 50 

Environment,  changes  in,  changesin  species 

coincident  with 33-34 

Eon,  definition  of 31, 133 

Epoch,  definition  of 31, 132 

Equivalency  of  geologic  formation,  deter- 
mination of,  diverse  data  used  for  .  117-120 

Era,  definition  of 31.133 

Erie  shale,  correlation  of 112, 120, 122 

Europe.  Devonian  faunas  of,  relations  of. . .        79 

Fauna,  definition  of 16, 29-30, 131-132 

Faunal  aggregates,  observations  on 28-32 

Faunal  time-scale,  definition  of 118 

Faunas,  association  of,  with  favorable  en- 
vironment       113 

biologic  equilibrium  of,  conditions  fa- 
voring   : 105-108 

classification  of 48-49 

correlation  of 81-82 

differences  in,  causes  of 35 

dissection  of,  for  New  York  province  ..  42-96 

distribution  of 16-20, 113 

facies  of 35 

integrity  of,  conditions  favoring 105-108 

local  expressions  of 25 

migration  of 18, 23-24, 31-32, 34-41 ,  97-1  If. 

migration  of,  geological  expression  of. .  33-41 

mingling  of 31, 103 

mutation  of 81-82 

nomenclature  of 20-27 

recurrences  of 113 

shifting  of 18,23-24,31-32,34-41,97-116 

shifting  of,  biological  consequencesof.  105-108 
effect  of,  on  classification  of  geolog- 
ical formations 108-116 

evidence  of 97-103 

principles  involved  in 103-105 

succession  of,  principles  involved  in.  105-108 

value  of,  as  time  indicators  in  geology.  101-103 

Faunule,  definition  of  term.  6(note),  24, 47, 131-132 

Faunules,  succession  of,  importance  of 25 

Fistulipora  occidens,  occurrence  of 79 

Flora,  definition  of 16 

Formational  time-scale,  definition  of  —  118, 119 
Formations,  geologic,  classification  of;   as 

affected  by  shifting  of  faunas 108 

correlation  of,  methods  used  for 117-120 

nomenclature  of 27-28 

time  relations  of,  basis  for  determining.        :1s 


INDEX. 


143 


Pase 

F«  ;ssiliferous  zones,  features  of 20-23 

subdivisions  of 21 

transgression  of 23 

Fossils,  association  of   certain  species  of, 

with  certain  kinds  of  sediments 113 

bionic  value  of 124-134 

Fossil  faunas,  use  of,  in  geologic  correlation, 

title  of  paper  on 27 

Geiger,  H.  R.,  work  done,  by 8 

Genesee  section,  faunal  zones  of 46 

Genesee  shale,  fossils  of 99 

geographic  extent  of 115 

stratigraphic  place  of 47. 99, 115, 122 

thickness  of 93 

Genesee  slate  fauna,  geologic  place  of 45 

Genesee  Valley,  Spirifer  disjunctus  fauna 

of 85 

Genera,  life  endurance  of 30-31 

Generation  or  generative  power,  utilization 
of,  as  a  measure  of  bionic  value  of 

fossils 124-134 

Geobios,  definition  of  term 14 

Geochron,  definition  of  term 31, 132 

Geologic  correlation,  importance  of 10 

methods  of 117-120 

work  done  in 10 

Geologic  faunas,  nomenclature  of . 20-27 

Geological  time-scale,  definition  of 118-119 

Glytocardia  speciosa,  occurrence  of 99 

stratigraphic  horizon  of 99 

Glyptocardia  speciosa  fauna,  geologic  place 

of 49 

epoch  of,  limits  of 133 

Glyptodesma  erectum,  occurrence  of 91 

Goniophora  hamiltonensis,  occurrence  of  . .        90 

Goniophora  subrecta,  occurrence  of 96 

Goniatite  beds,  geologic  place  of 50 

Grabau,  A.  W.,  aid  by 49, 57 

cited  on  fossils  from  EighteenmileCreek, 
New  York 92 

cited  on  Hamilton  fauna  of  Eighteen- 
mile  Creek 80 

cited  on  Hamilton  fauna  of  Michigan. .        65 

Grammysia,  occurrence  of 90 

Grammysia  bisulcata,  occurrence  of 95 

Grammysia  circularis,  occurrence  of 95 

Grammysia  communis,  occurrence  of.. .  85, 86, 96 

Grammysia  elliptica,  occurrence  of 77, 78, 95 

Grammysia  globosa,  occurrence  of 77 

Grammysia  nodocostata,  occurrence  of 77, 95 

Grammysia  subarcuata,  occurrence  of 74, 95 

H. 

Haeckel.  Ernst,  names  for  biologic  aggre- 
gates proposed  by 14 

Hall,  James,  cited  on  Glyptocardia  (Cardi- 

ola)  speciosa 49 

Hall,  James,- and  Clarke,  J.  M.,  cited  on 
common  features  possessed  by  many 
orthids 85 

Halobios,  definition  of  term 14 

Hamilton  fauna,  stages  or  faunules  of 47 

geologic  place  of 122,  123 


Page. 

Hamilton  formation,  beds  composing 50 

character  of 114 

extent  and  limits  of 68, 114 

fauna  of,  identity  of,  with  that  of  part 

of  Chemung  formation 38 

faunas  of 47, 48, 50-56, 103, 114-115 

lithologic  characters  of 114 

stratigraphic  place  and  equivalents  of  .      4">, 
47, 50, 122, 123 

thickness  of 93 

Harris,  G.  D.,  aid  by 9,49 

cited  on  fauna  of  the  Chemung  forma- 
tion    85-86 

Harris,   G.   D..  and   Dall,  W.  H.,  work   in 

geologic  correlation  done  by 10 

Heliophyllum  halli  zone,  geologic  place  of.        45 

Hemera,  definition  of 31, 102, 132 

faunal  equivalent  of 31, 130 

Heterotopic,  term  proposed 54  (note) 

High  Point,  Naples,  N.  Y.,  fauna  at 78-79 

Holonema  rugosa,  occurrence  of 96 

Homeotopic,  term  proposed 50  (note) 

Huron  shales,  equivalents  of 122 

Huxley,  T.  H.,  cited 33 

Hypothyris  cuboides,  occurrence  of 78 


Illinois,  Hamilton  formation  in,  fauna  of..        66 
Indiana,  Tropidoleptus  carinatus  fauna  in.  66-67 
International  Congress  of  Geologists,   ex- 
tract from  Compte  Rendu  of 11-12 

Iowa,  Devonian  faunas  of,  relations  of 79 

Ithaca,  N.  Y.,  investigations  begun  at 6,  7 

Ithaca  formation  at,  fauna  of 73-76 

Ithaca  fauna,  geologic  place  of 45 

mingling  of,  with  Chemung  fauna 100 

Ithaca  formation  or  group,  correlation  of. .       47, 
99, 103, 104, 109, 112, 115 

fauna  of 45, 50, 73-76, 78-81, 88, 95, 98, 115 

geologic  horizon  of 47, 

99, 103, 104, 109, 112, 115, 120, 122, 123 

immigrant  species  of 78-81 

limits  of .     43 

sediments  forming,  features  of 110 

stratigraphic  equivalents  of 47, 

99, 103, 104, 109, 112, 115, 120, 122, 123 
thickness  of , 93 


Juliand  Hill,  Chenango  County,  New  York, 

fossils  found  at 94 

K. 

Kindle,  E.  M.,  aid  by 9,49 

cited  on  fauna  of  Ithaca  formation 73, 80 

cited  on  Tropidoleptus  carinatus  fauna 

of  Indiana 66 

work  done  by 8 


Lamellibranch  fauna,  geologic  place  of 46 

Leda  brevirostns,  occurrence  of 77 

Leda  diversa,  occurrence  of 72, 95 

Leiopteria  bigsbyi,  occurrence  of 90, 95 


144 


INDEX. 


Page. 
Leiopteria  rafinesquii 96 

Leiorhynchus  fauna,  geologic  place  of -46 

Leiorhynchus  globuliforme,  occurrence  of.  96, 98 
Leiorhynchus  globuliforme  stage  or  faun- 

ule,  geologic  place  of 47, 97-98, 115 

Leiorhynchus  laura,  occurrence  of 62, 63 

Leiorhynchus  mesicostale,  occurrence  of  . .       72, 

74,76,77,95,98 

Leptodesma  matheri,  occurrence  of 91 

Lepdodesma  sociale,  occurrence  of 96 

Limestone,  uniform  character  of  fossils  of, 

through  long  periods 33 

Limnobios,  definition  of 14 

Lingula,  occurrence  of 90 

Lingula  fauna,  geologic  place  of 45, 46 

Lingula  complanata  stage  or  faunule,  geo- 
logic place  of 47 

Lingula  spatulata  stage  or  faunule,  geo- 
logic place  of 47, 48, 69 

Liopteria.     See  Leiopteria. 
Lithologic  characters,  valuelessness  of,  in 
discriminating  time  equivalency  of 

formations 101 

Livonia  salt  shaft,  faunas  of 63-64 

Loxonema  delphicola,  occurrence  of 90, 95 

Loxonema  hamiltonise,  occurrence  of 95 

Lunulicardium  fragile,  occurrence  of 95 

Lunulicardium  ornatus,  occurrence  of 77 

Lyriopecten  priamus,  occurrence  of 96 

Lyriopecten  tricostatus,  occurrence  of 96 

M. 

Macrodon  hamiltonise,  occurrence  of 90 

Mackenzie  River  Valley,  faunas  of,  rela- 
tions of 79 

Marcellus  shale,  geologic  place  of 50,122 

thickness  of 93 

Maryland  Geological  Survey,  paleontologic 

work  by 8 

Mauch    Chunk    formation,    stratigraphic 

equivalents  of 122 

Metropolis  of  a  fauna,  definition  of  term. . .        25 
Michigan,  Hamilton  formation  in,  fauna  of.        65 
Migrations   of   faunas,   geological   expres- 
sion of 33-41 

observations  on 18, 23-24, 31, 34-41, 97-116 

variations  of  specific  forms  due  to 40-41 

Mingling   of   faunas,   expression    and  ex- 
amples of 31, 103 

Modiella  pygmsea,  occurrence  of 56 

Modiomorpha  complanata,  occurrence  of. .        70 
Modiomorpha  cf.  concentrica,  occurrence 

of 91 

Modiomorpha  mytiloides,  occurrence  of. . .        90 

Mndinniorpha  quadrula,  occurrence  of 96 

Modiomorpha  subalata  var.  chemungensis, 

occurrence  of 72, 74, 77 

Monobion,  definition  of  term ' 102 

Monroe   and   Teller,    cited   on    Hamilton 

fauna  of  Wisconsin 65 

Moscow  shales,  geologic  place  of 50 

Mutation  of  species,  definition  and  discus- 
sion of 17, 81-82 

Myrtilarca  carinata,  occurrence  of 96 

Mytilarca  chemungensis,  occurrence  of .  85,86,87 


N". 

-face. 

Necton,  definition  of 14 

Nucula  bellistriata,  occurrence  of 51, 

56,  58,  59,  60,  62,  63,  75 

Nucula  corbuliformis,  occurrence  of 51, 

56,  58,  59,  60,  62,  63,  65,  71,  75 

Nuculites  cuneiformis,  occurrence  of 95 

Nuculites  oblongatus,  occurrence  of 51, 

56,  59,  60,  62,  63,  71,  75,  95 

Nuculites  triqueter,  occurrence  of 51, 

56,  58,  59,  60,  62,  63,  64,  75 

O. 

Ohio,  Devonian  formations  of,  correlation 

of 120-123 

Ohio  shale,  correlation  of 109,  112 

Old  Red  sandstone,  intermediate  faunas  of.         7 
Olean  conglomerate  fauna,  geologic  place 

of 47 

Oneonta   sandstones,  character  and  fossil 

content  of 110-111 

correlation  of. .  99, 100, 103, 104, 109, 112, 120, 122 

deposition  of,  conditions  during Ill 

fauna  above 94-95, 97 

fauna  of 48, 97 

faunal  shifting  in 97-103,115 

geologic  horizon  of,  variation  of,  in  dif- 
ferent localities 108-109 

shifting  of  faunas  coincident  with  de- 
position of 97-103, 115 

stratigraphic  horizon  and  equivalents 

of 99, 100-103, 104,  109, 112 

thickness  of 93 

Ontario,  Canada,  Hamilton  formation  in, 

fauna  of 64-65 

Onychodus  hopkinsi,  occurrence  of 96 

Orbiculoidea  media,  occurrence  of 64, 77 

Orbiculoidea  neglecta,  occurrence  of 77 

Organic  values,  measurement  of,  discussion 

of  methods  of 124-134 

Orthis  (=Schizophoria) ,  common  features  of 

many  species  of 85 

Orthis  carinata,  occurrence  of 86 

Orthis  (Dalmanella)  leonensis,  occurrence 

of.: 87 

Orthis  leonensis  zone,  geologic  place  of 46 

Orthis  (Schizophoria)  impressa,  occurrence 

of 85,86,87,95 

Orthis  (Schizophoria)  tioga,  occurrence  of.  83,86 
Orthis  tioga  stage  or  faunule,  geologic  place 

of 45,48 

Orthis  (Schizophoria)  tulliensis,  occurrence 

of 78 

Orthis  vanuxemi,  occurrence  of 64 

Orthoceras  bebryx  cayuga,  occurrence  of. .        74 

Orthoceras  nuntium,  occurrence  of 64 

Orthonota  undulata,  occurrence  of 95 

Orthothetes  arctistriatus,  occurrence  of.  57, 58, 64 
Orthothetes  chemungensis,  occurrence  of. .      79, 

83,85,86,87,92 
Orthothetes  chemungensis  arctistriatus,  oc- 
currence of 92 

Owego,  N.  Y.,  fossils  found  at 89-90 


Palseanatina  typa   fauna,   formation   con- 
taining    46, 48 


INDEX. 


145 


Page. 

Palseoneilo,  occurrence  of 90 

Palseoneilo  brevis,  occurrence  of 96 

Palseoneilo  brevis   quadrangularis,  occur- 
rence of 96 

Palseoneilo  constricta,  occurrence  of 51, 

56, 58,  59,  60, 62, 63,  65,  71,  74,  75,  86,  92,  95,  96 

Palseoneilo  emarginata,  occurrence  of 72 

Palseoneilo  filosa,  occurrence  of 72, 74, 95 

Palseoneilo  plana,  occurrence  of 95 

Panama  conglomerate;  stratigraphic  equiv- 
alent of 122 

Papers  and  books  consulted,  list  of 135-139 

Paracyelas  lirata,  occurrence  of . . .  62, 63, 72, 76, 77 
Paracyclas  lirata  stage  or  faunule,  geologic 

place  of 47 

Period,  definition  of 31, 132 

Phacops  bufo.    See  Phacops  rana, 

Phacops  rana,  occurrence  of 51, 56, 57, 59, 

60,  61,  62, 63, 64, 65,  67,  68,  71, 75,  82, 89, 90 

Plankton,  definition  of 14 

Plant  and  animal  aggregates,  discussion  of.  13-20 

Pleurotomaria  itys,  occurrence  of 96 

Pleurotomaria  capillaria,  occurrence  of 70,  74 

Pocono  formation,  equivalents  of 122 

Portage  fauna,  faunules  of 48 

geologic  place  of 47 

Portage  (Ithaca)  fauna,  mingling  of,  with 

Portage  (Naples)  fauna 103 

Portage  formation  or  group,  correlation  of.     100, 
103, 104, 109, 112 

Eastern  extension  of,  fauna  of 71-73 

faunas  of 45, 48,  99 

features  of  sediments  forming. 110 

stratigraphic  equivalents  of 47, 

99, 100, 104, 109, 111-112, 122 

thickness  of 45 

Powell,  J.  W.,  aid  rendered  by 8 

cited  on  importance  of  geologic  correla- 
tion         10 

Primitiopsis  punctilifera,  occurrence  of.  57, 58, 64 

Productella  costatula,  occurrence  of 87 

Productella     (dissimilis)     hallana,    occur- 
rence of 7s,  79 

Productella  hirsuta,  occurrence  of 87, 88 

Productella  hystricula,  occurrence  of 86 

Productella  lachrymosa,  occurrence  of 70, 

83,85,86,88,91,94,96 
Productella  speciosa,   evolutionary  prede- 
cessor of 78 

Productella  speciosa,  occurrence  of 74,88,90 

Productella  speciosa  fauna,  epoch  of 133 

geologic  place  and  equivalent  of 50, 98 

mutation  and  correlation  of 81-82 

occurrence  of 70, 115 

tables  showing 74,  75, 76, 77 

Productella  spinulicosta,  evolutionary  suc- 
cessor of 78 

occurrence  of 57, 58, 64 

Prosser,  C.  S.,  aid  by 9, 49, 67 

cited  on  Chemung  formation,  limits  of.        93 

cited  on  Chemung  fossils 94-95 

cited  on  fauna  of  eastern  New  York 75 

cited  on  fauna  of  Unadilla  region 62 

cited  on  fossils  from  Port  Crane,  N.  Y..        94 
cited  on  Hamilton  fauna 51, 80 

Bull.  210—08 10 


Page. 
Prosser,  C.  S.,  cited  on  post-Oneonta  fauna 

of  eastern  New  York 93-94 

work  done  by 8 

Proetus  canaliculars,  occurrence  of 67 

Prothyris  lanceolata,  occurrence  of 72,  77 

Pterinea,  occurrence  of 90 

Pterinea  chemungensis,  occurrence  of 83, 86 

Pterinopecten,  occurrence  of 91 

Pterinopecten  crenicostatus,  occurrence  of.        91 
Pterinopecten    suborbicularis,    occurrence 

of 77 

Pugnax  pugnus,  occurrence  of 78,  7'.),  88,  96 

Race,  discussion  of  term 127-130 

Range,  geological,  of  faunas,  observations 

on 16-20 

Red  sandstones,  fossils  contained  in Ill 

sediments  forming,  features  of 110-112 

Renevier,  E.,  cited 28-29 

Reticularia.    See  Spirifer. 
Rhipidomella.     See  also  Orthis. 

Rhipidomella  vanuxemi,  occurrence  of 57, 

58,64,91 
Rynchonella.    See  also  Camarotcechia. 
Rhynchonella  allegania,  geologic  place  of.        46 

Rhynchonella  contracta,  occurrence  of 85 

Rhynchonella  contracta  stage  or  faunule, 

geologic  place  of 48 

Rhynchonella  (Hypothyris)  cuboides  (  =  R. 

venusta) ,  occurrence  of 69 

Rhynchonella  eximia,  occurrence  of 85 

Rhynchonella  pugnus.  See  Pugnax  pugnus. 

Rhynchonella  sappho,  occurrence  of 85 

Rhynchonella  stephani,  occurrence  of 72 

Rhynchonella  venustula,  occurrence  of  . . .        78 

Roemerella  grandis,  occurrence  of 67 

Rominger,  C,  cited  on  fauna  of  Hamilton 

formation  in  Michigan 65 

Romney  formation,  Maryland,  fauna  of  ...        67 
Russell,  T.  C,  work  in  geologic  correlation 

done  by 10 

S. 

Sandstones,  variability  of  fossils  of 33 

Sayles,  Ira,  work  done  by 8 

Schizodus  chemungensis,  occurrence  of 96 

Schizodus   chemungensis   quadrangularis, 

occurrence  of 96 

Schizodus  ellipticus,  occurrence  of 77 

Schizodus  gregarius,  occurrence  of 96 

Schizophoria  (=  Orthis) ,  common  features  of 

many  species  of 85 

Schizophoria  carinata,  occurrence  of 83 

Schizophoria  cf .  concentrica,  occurrence  of.  91 

Schizophoria  iowensis,  occurrence  of 79 

Schizophoria  striatula  (=  Orthis  impressa), 

occurrence  of 85, 86, 87, 95 

Schizophoria  striatula  impressa,  occurrence 

of 85 

Schizophoria  striatula,  variation  of 78 

Schizophoria  tioga  (=  Orthis  tioga),  occur- 
rence of 83, 86 


146 


INDEX. 


Page. 
Schuchert,  Charles,  cited  on  brachiopods 

of  the  Chemung  fauna 85 

Sediments,  different  classes  of,  limited  dis- 
tribution of 113 

Sellersburg  formation,  equivalents  of 123 

fossils  of 66-67 

Shales,  variability  of  fossils  of 33 

Sherburne  formation,  geologic  horizon  of.  112,122 

thickness  of 93 

Shifting  of  faunas,  biological  consequences 

of 105-108 

effect,  of,   on    classification    of   forma- 
tions    108-116 

evidence  of 97-103 

observations  on IS 

principles  inv<  lived  in 103-105 

South  America;  Devonian  faunas  of,  rela- 
tions of 79 

Species,  definition  of  term 127-130 

life  endurance  of 30-31 

mutation  of 17, 81-82 

Sphenotus  contractus,  occurrence  of.  85, 86, 87, 96 

Spirifer  (Cyrtia)  altus,  occurrence  of 88 

Spirifer  altus  fauna,  geologic  place  of 48 

Spirifer  bimesialis,  occurrence  of 79 

Spirifer  disjunctus,  occurrence  of 61, 

78,  S3, 85, 86, 87, 88, 89, 91, 94, 96, 122 
Spirifer  disjunctus  fauna,  epoch  of,  limits 

of 133 

faunules  or  stages  of 48 

fossils  of,  lists  showing 83, 85, 86, 87, 88, 94 

geologic  place  of 46, 49, 50 

occurrence  of 69,82,83-89, 

91, 92, 93, 94, 95, 96, 97, 99, 100, 116, 133 

Spirifer  fimbriatus,  occurrence  of 70 

Spirifer  granulosus,  occurrence  of 51, 

58, 59, 60, 62, 63, 64, 65, 67,  75, 90, 95 

Spirifer  hungerfordi,  occurrence  of 79 

Spirifer  (Retieularia)  laevis,  occurrence  of. .       78 
Spirifera  laevis  stage  or  faunule,  geologic 

place  of 45, 47, 69 

Spirifer  marcyi,  occurrence  of 88, 90, 91 

Spirifer  medialis,  occurrence  of 62 

Spirifer    (Delthyris)     mesicostalis,     occur- 
rence of 61,  70.  72,  83, 85, 88 

Spirifer  mesicostalis  fauna,  geologic  place 

of 45,46 

Spirifer  mesistrialis,  occurrence  of 72, 

74,  76, 77, 83, 85,  86,  88,  94, 95, 96 
Spirifer  mesistrialis  stage  or  faunule,  geo- 
logic place  of 47,  s^ 

Spirifer  orestes,  occurrence  of 79 

Spirifer  (mucronatus)  pennatus,  occurrence 

of 51,52, 

56, 57, 59, 60, 62,  63,  64,  65,  67,  70,  71, 75,  76 
Spirifer  (mucronatus)  pennatus  fauna,  geo- 
logic place  of 48 

Spirifer  pennatus  posterus,  occurrence  of  . .       70, 
71,72,74,77,88,95,96 

Spirifer  subattenuatus,  occurrence  of 79 

Spirifer  verneuili,  identity  of,  with  S.  dis- 
junctus. 
Spirigera   concentrica   (  =  Athyris  spirifer- 

oides)  occurrence  of 65 

Stevenson,  .7.  J.,  aid  by 49 

Stictopora,  occurrence  of 67 


Page. 

Stictopora  meeki,  occurrence  of 74 

Streptelasma  rectum,  occurrence  of 64 

Streptorhynchus  fauna,  geologic  place  of . .        46 
Strophalosia  hystricula.     See  Productella 

hystricula. 

Stropheodonta  arcuata,  occurrence  of 79 

Stropheodonta  calvini,  occurrence  of 79 

Stropheodonta  canace,  occurrence  of 79 

Stropheodonta  cayuta,  occurrence  of 83 

Stropheodonta  demissa,  occurrence  of 67 

Stropheodonta  mucronata,  occurrence  of  ..  74,83 
Stropheodonta  (Cayuta)  mucronata  stage  or 

faunule,  geologic  place  of 47, 48 

Stropheodonta  perplana,  occurrence  of 56, 

57, 58, 63, 67 

Stropheodonta  variabilis,  occurrence  of 79 

Strophonella  reversa,  occurrence  of 79 

Succession  of  faunas,  methods  of 105-108 

T. 

Teller  and  Monroe,  cited  on  Hamilton  fauna 

of  Wisconsin 65 

Tellinopsis  subemarginata,  occurrence  of..        56 
Time-scale,  bionic,  tabular  presentation  of.    132- 

134 
Time-scales,  faunal,  formational,  and  geo- 
logical, definitions  of 118-120 

Time  values  in  geology,  title  of  paper  on  . .        27 
Trilobite  eon,  table  showing  classification 

and  nomenclature  of 133 

Tropidoleptus  earinatus,  occurrence  of 51, 

56,59,60,61,62,63,64,67,71, 
72,  75,  76,  82,  89,  90,  91, 95, 96 
Tropidoleptus  earinatus  fauna,  definition  of 

term ."  131-132 

distributional  values  of  species  compos- 
ing          52 

dominant  species  of,  lists  of 58-62 

frequency  values  of  species  composing.       52 

geologic  place  of 43, 47, 48, 50 

mutation  and  correlation  of 81-82 

occurrence  of 81, 82, 89-92, 

95,  97,  99, 100,  111,  114-115, 116, 120, 122, 123 

range  values  of  species  composing 53-54 

species  characteristic  of 51, 89-90 

tables  of 51, 56, 57, 62-66, 71-72 

tables  of,  Cayuga  Lake  section 51-56 

Eighteenmile  Creek 57 

Illinois 66 

Michigan .- .        65 

New  York  (eastern)  and  Pennsyl- 
vania         63 

Ontario.  Canada 64 

Portage  formation 70-72 

Unadilla  region 62 

Wisconsin 65-66 

Tully  limestone,  extent  of 115 

geologic  horizon  of 50, 115, 122 

thickness  of 93 


Unadilla  region,  fauna  of . 


62 


Van  llise,  C.  R.,  work  in  geologic  correla- 
tion done  by 10 


INDEX. 


147 


Page. 

Van  Ingen,  Gilbert,  acknowledgments  to. .  9 

work  done  by 8 

Variation  of  specific  forms,  conditions  influ- 
encing   35-3(5 

definition  of 17 

Verrill,  A.  E.,  cited  on  adjustment  of  faunas 

to  local  conditions 106 

Wagner,  Moritz,  extract  from  letter  from 

Charles  Darwin  to 33 

Walcott,  C.  D.,  aid  rendered  by 8 

work  in  geologic  correlation  done  by  . .  10 
Walther,  J.,  names  for  biologic  aggregates 

adopted  by 11 

Waverly  fauna,  geologic  place  of 47, 122 

Waverly  group,  fauna  of 48 

stratigraphic  equivalents  of 122 

■  Weller,  Stuart,  aid  by 9, 49 

cited  on  fauna  of  Hamilton  formation 

of  Illinois 66 

work  done  by 8 


Page. 
White,  C.  A.,  work  in  geologic  correlation 

done  by 10 

Whiteaves,  J.  F.,  cited  on  fauna  of  Hamil- 
ton formation  of  Ontario,  Canada 60, 64 

Williams,  H.  S.,  cited 8, 12, 

27,  30, 39, 42, 43, 44,  45, 47,  69,  70, 79, 80 
work  in  geologic  correlation  done  by  . .        10 

Willis,  Bailey,  cited 38 

Wisconsin,  Hamilton  fauna  of 65-66 

Williams,  S.  G.,  aid  by 49 

Wolf  Creek  conglomerate,  fauna  of 48 


Y. 


Yak-  University,  work  done  by  students  of.  8, 9, 43 


Z. 


Zones,  fossiliferous,  features  of 20-23 

subdivisions  of 21 

transgression  of 23 

Zoological  classification,  principles  of 15-16 


o 


PUBLICATIONS  OF  UNITED  STATES  GEOLOGICAL  SURVEY. 

[Bulletin  No.  210.] 

The  serial  publications  of  the  United  States  Geological  Survey  consist  of  (1)  Annual 
Reports,  (2)  Monographs,  (3)  Professional  Papers,  (4)  Bulletins,  (5)  Mineral  Re- 
sources, (6)  Water-Supply  and  Irrigation  Papers,  (7)  Topographic  Atlas  of  United 
States — folios  and  separate  sheets  thereof,  (8)  Geologic  Atlas  of  United  States — 
folios  thereof.  The  classes  numbered  2,  7,  and  8  are  sold  at  cost  of  publication;  the 
others  are  distributed  free.  A  circular  giving  complete  lists  may  be  had  on  appli- 
cation. 

The  Bulletins,  Professional  Papers,  and  Water-Supply  Papers  treat  of  a  variety  of  sub- 
jects, and  the  total  number  issued  is  large.  They  have  therefore  been  classified  into 
the  following  series:  A,  Economic  geology;  B,  Descriptive  geology;  C,  Systematic 
geology  and  paleontology;  D,  Petrography  and  mineralogy;  E,  Chemistry  and  phys- 
ics; F,  Geography;  G,  Miscellaneous;  H,  Forestry;  I,  Irrigation;  J,  Water  storage; 
K,  Pumping  water;  L,  Quality  of  water;  M,  General  hydrographic  investigations; 
N,  Water  power;  0,  Underground  waters;  P,  Hydrographic  progress  reports.  This 
bulletin  is  the  sixty-first  in  Series  C,  the  complete  list  of  which  follows  (all  are 
bulletins  thus  far) : 

SERIES  C,  SYSTEMATIC  GEOLOGY  AND  PALEONTOLOGY. 

3.  Fossil  faunas  of  Upper  Devonian,  along  the  meridian  76°  30',  from  Tompkins  County,  New  York,  to 

Bradford  County,  Pennsylvania,  by  H.  S.  Williams.    1884.    36  pp. 

4.  Mesozoic  fossils,  by  C.  A.  White.    1884.    36  pp.,  9  pis. 

10.  Cambrian  faunas  of  North  America.    Preliminary  studies,  by  C.  D.Walcott.    1884.    74  pp.,  10  pis. 

(Out  of  stock.) 

11.  Quaternary  and  recent  Mollusca  of  the  Great  Basin,  with  descriptions  of  new  forms,  by  R.  Ells- 

worth Call.    Introduced  by  a  sketch  of  the  Quaternary  lakes  of  the  Great  Basin,  by  G.  K. 
Gilbert.    1884.    66  pp.,  6  pis. 

15.  Mesozoic  and  Cenozoic  paleontology  of  California,  by  C.  A.  WThite.    1885.    33  pp. 

16.  Higher  Devonian  faunas  of  Ontario  County,  New  York,  by  J.  M.  Clarke.    1885.    86  pp.,  3  pis. 

18.  Marine  Eocene,  fresh-water  Miocene,  and  other  fossil  Mollusca  of  western  North  America,  by 

C.  A.  White.    1885.    26  pp.,  3  pis. 

19.  Notes  on  the  stratigraphy  of  California,  by  G.  F.  Becker.    1885.    28  pp.     (Out  of  stock.) 
22.  New  Cretaceous  fossils  from  California,  by  C.  A.White.    1885.    25  pp.,  5  pis. 

24.  List  of  marine  Mollusca,  comprising  the  Quaternary  fossils  and  Recent  forms  from  American 
localities  between  Cape  Hatteras  and  Cape  Roque,  including  the  Bermudas,  by  W.  H.  Dall. 

1885.  336  pp. 

29.  Fresh- water  invertebrates  of  the  North  American  Jurassic,  by  C.  A.  White.    41  pp.,  4  pis. 

30.  Second  contribution  to  the  studies  on  the  Cambrian  faunas  of  North  America,  by  C.  D.  Walcott. 

1886.  369  pp.,  33  pis.     (Out  of  stock.) 

31.  Systematic  review  of  our  present  knowledge  of  fossil  insects,  including  myriapods  and  arachnids, 

by  S.  H.  Scudder.    1886.    128  pp. 
34.  Relation  of  the  Laramie  molluscan  fauna  to  that  of  the  succeeding  fresh-water  Eocene  and  other 

groups,  by  C.  A.  White.    1886.    54  pp.,  5  pis. 
37.  Types  of  the  Laramie  flora,  by  L.  F.  Ward.    1887.    354  pp.,  57  pis. 
41.  Fossil  faunas  of  the  Upper  Devonian— the  Genesee  section,  New  York,  by  H.  S.  Williams.    1887. 

121  pp.,  4  pis. 
43.  Tertiary  and  Cretaceous  strata  of  the  Tuscaloosa,  Tombigbee,  and  Alabama  rivers,  by  E.  A.  Smith 

and  L.  C.  Johnson.    1887.    189  pp.,  21  pis. 
51.  Invertebrate  fossils  from  the  Pacific  coast,  by  C.  A.  White.    1889.    102  pp.,  14  pis.     (Out  of  stock.) 
56.  Fossil  wood  and  lignite  of  the  Potomac  formation,  by  F.  H.  Knowlton.    1889.    72  pp.,  7  pis. 
63.  Bibliography  of  Paleozoic  Crustacea  from  1698  to  1889,  including  a  list  of  North  American  species 

and  a  systematic  arrangement  of  genera,  by  A.  W.  Vogdes.    1890.    177  pp. 
69.  Classed  and  annotated  bibliography  of  fossil  insects,  by  S.  H.  Scudder.    1890.    101  pp. 
71.  Index  to  known  fossil  insects  of  the  world,  including  myriapods  and  arachnids,  by  S.  H.  Scudder. 

1891.    744  pp. 

I 


II  ADVERTISEMENT. 

77.  The  Texan  Permian  and  its  Mesozoic  types  of  fossils,  by  C.  A.  White.    1891.  "  51  pp.,  4  pis. 

80.  Correlation  papers — Devonian  and  Carboniferous,  by  H.  S.  Williams.    1891.    279  pp. 

81.  Correlation  papers— Cambrian,  by  C.  D.  Walcott.    1891.    447  pp.,  3  pis.     (Out  of  stock.) 

82.  Correlation  papers— Cretaceous,  by  C.  A.  White.    1891.    273  pp.,  3  pis. 

83.  Correlation  papers— Eocene,  by  W.  B.  Clark.    1891.    173  pp.,  2  pis. 

84.  Correlation  papers— Neocene,  by  W.  H.  Dall  and  G.  D.  Harris.    1892.    349  pp.,  3  pis. 

85.  Correlation  papers— The  Newark  system,  by  I.  C.  Russell.    1892.    344  pp.,  13  pis.     (Out  of  stock.) 

86.  Correlation  papers— Archean  and  Algonkian,  by  C.  R.  Van  Hise.    1892.    549  pp.,  12  pis.     (Out  of 

stock.) 

87.  Synopsis  of  American  fossil   Brachiopoda,  including  bibliography  and  synonymy,  by  Charles 

Schuchert.    1897.    464  pp. 

88.  Cretaceous  Foraminifera  of  New  Jersey,  by  R.  M.  Bagg,  jr.    1898.    89  pp.,  6  pis. 

93.  Some  insects  of  special  interest  from  Florissant,  Colo.,  and  other  points  in  the  Tertiariesof  Colo- 
rado and  Utah,  by  S.  H.  Scudder.    1892.    35  pp.,  3  pis. 

97.  Mesozoic  Echinodermata  of  the  United  States,  by  W.  B.  Clark.    1893.    207  pp.,  50  pis. 

98.  Flora  of    the  outlying  Carboniferous  basins  of  southwestern  Missouri,  by  David  White.    1893. 

139  pp.,  5  pis. 

101.  Insect  fauna  of  the  Rhode  Island  coal  field,  by  S.  H.  Scudder.    1893.    27  pp.,  2  pis. 

102.  Catalogue  and  bibliography  of  North  American  Mesozoic  Invertebrata,  by  C.  B.  Boyle.    1893. 

315  pp. 

105.  The  Laramie  and  the  overlying  Livingston  formation  in  Montana,  by  W.  H.  Weed,  with  report 

on  flora,  by  F.  H.  Knowlton.    1893.     68  pp.,  6  pis. 

106.  Colorado  formation  and  its  invertebrate  fauna,  by  T.  W.  Stanton.    1893.    288  pp.,  45  pis.     (Out  of 

stock.) 
110.  Paleozoic  section  in  the  vicinity  of  Three  Forks,  Mont.,  by  A.  C.  Peale.    1893.    56  pp.,  6  pis. 

120.  Devonian  system  of  eastern  Pennsylvania  and  New  York,  by  C.  S.  Prosser.    1895.    81  pp.,  2  pis. 

121.  Bibliography  of  North  American  paleontology,  by  C.  R.  Keyes.    1894.    251  pp. 

124.  Revision  of  North  American  fossil  cockroaches,  by  S.  H.  Scudder-*    1895.    176  pp.,  12  pis. 
128.  Bear  River  formation  and  its  characteristic  fauna,  by  C.  A.  White.    1895.    108  pp.,  11  pis. 

133.  Contributions  to  the  Cretaceous  paleontology  of  the  Pacific  coast:  The  fauna  of  the  Knoxville 

beds,  by  T.  W.  Stanton.    1895.    132  pp.,  2d  pis. 

134.  Cambrian  rocks  of  Pennsylvania,  l>y  ('.  D.  Walcott.     1896.    43  pp.,  15  pis. 

141.  Eocene  deposits  of  the  middle  Atlantic  slope  in  Delaware,  Maryland,  and  Virginia,  by  W.  B. 

Clark.     1896.     167  pp.,  40  pis. 

142.  Brief  contribution  to  the  geology  and    paleontology   of    northwestern    Louisiana,  by  T.  W. 

Vaughan.     1896.     65  pp.,  4  pi-. 
145.  Potomac  formation  in  Virginia,  by  W.  M.  Fontaine.     1896.     149  pp.,  2  pis. 

151.  Lower  Cretaceous  gryphseas  of  the  Texas  region,  by  R.  T.  Hill  and   T.  W.  Vaughan.    1898. 

139  pp.,  35  J  .Is. 

152.  Catalogue  of    Cretaceous  and  Tertiary  plants  of  North  America,  by  F.  H.  Knowlton.    1898. 

247  pp. 

153.  Bibliographic  index  of  North  American  Carboniferous  invertebrates,  by  Stuart  Weller.    1898. 

653  pp. 
163.  Flora  of  the  Montana  formation,  by  F.  H.  Knowlton.     1900.    118  pp.,  19  pis. 
173.  Synopsis  of  American   fossil  Bryozoa,  including  bibliography  and  synonymy,  by  J.  M.  Nickles 

and  R.  S.  Bassler.    1900.    663  pp. 
179.  Bibliography  and  catalogue  of  fossil  Vertebrata  of  North  America,  by  O.  P.  Hay.    1902.    868  pp. 
191.  North  American  geologic  formation  names:  Bibliography,  synonymy,  and  distribution,  by  F.  B. 

Weeks.    1902.    448  pp. 
l',»">.  structural  details  in  the  Green  Mountain  region  and  in  eastern  New  York  (second  paper),  by 

T.  N.  Dale.     1902.    22  pp.,  4  pis. 

204.  Fossil  flora  of  the  John  Day  Basin,  Oregon,  by  F.  H.  Knowlton.    1902.    153  pp.,  17  pis.' 

205.  The  mollusca  of  the  Buda  limestone,  by  G.  B.  Shattuck,  with  an  appendix  on  the  corals  of  the 

Buda  limestone,  by  T.  W.  Vaughan.    1903.    94  pp.,  27  pis. 

206.  A  study  of  the  fauna  of  the  Hamilton  formation  of  the  Cayuga  Lake  section  in  central  New 

York,  by  H.  F.  Cleland.    1903.    112  pp.,  5  pis. 
210.  The  correlation  of  geological  faunas,  a  contribution  to  Devonian  paleontology,  by  H.  S.  Williams. 
1903.     147  pp.,  1  pi. 


.    LIBRARY  CATALOGUE   SLIPS. 

[Mount  each  slip  upon  a  separate  card,  placing  the  subject  at  the 
top  of  the  second  slip.  The  name  of  the  series  should  not  be 
repeated  on  the  series  card,  but  add  the  additional  numbers,  as 
received,  to  the  first  entry.] 


Williams,  Henry  Shaler. 

.  .  .  The  correlation  of  geological  faunas,  a  con- 
tribution to  Devonian  paleontology;  by  Henry 
Shaler  Williams.  Washington,  Gov't  print,  off., 
1903. 

147.  Ill  p.      1  pi.     23£om.     (IT.  S.  Geological  Survey.     Bulletin 

no.  210.) 
''Bibliography'*:  p.  135-139. 
Subject  series  C,  Systematic  geology  and  paleontology,  61. 


Williams,  Henry  Shaler. 

.  .  .  The  correlation  of  geological  faunas,  a  con- 
tribution to  Devonian  paleontology;  by  Henry 
Shaler  Williams.  Washington,  Gov't  print,  off., 
1903. 

147,  III  p.     1  pi.     2SVm.     (U.  S.  Geological  Survey.     Bulletin 

no.  210.) 
"Bibliography"':  p.  135-139. 
Subject  series  C,  Systematic  geology  and  paleontology,  61. 


U.  S.  Geological  survey. 
Bulletins. 

no.  210.  Williams,  H.  S.  The  correlation  of  geo- 
logical faunas,  a  contribution  to  Devonian 
paleontology.      1903 

U.  S.  Dept.  of  the  Interior. 
see  also 
U.  S.  Geological  survey. 

in 


119  ■■11 

I 
llllil 


fill 

m 


nil 


1 8 


ill 


111 
II 


1 

« 

a 

n 

'  ,■ 

III 


lllli 

nimiWtuiu 

: '' .  ? 

\  iPmHillSH 

|  IJkiijfw 

a      t  |  * . ;,  i  -  >  j  f  ' 

if  tficilH 

■' 

ll««i 

1  fMfnJ'I:fffcJ<Hfv 

liWim 

1 

lllllllj 

;jij|i*$jjj$ 

;  t  f  *  i 

Ififlf!