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

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Bulletin No. 210 



Series C, Systematic Geology and Paleontology, 61 



DEPARTM ENT 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 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 "faunule 11 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? 
W r hat 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 bj r 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 w T ould 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} r pical 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 the3 T 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 t3 T pical 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. Prosser a 
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 feet 6 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 . 

Nucula corbulif ormis . 

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 



IT) 


Orthothetes arctistriatus 

Rhipidomella vanuxemi 

Productella spinulicosta . . 
Cryphaeus boothi. 


12 

17 



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 



51 

3 

6 



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. Grabau 6 does not increase the number of species of the domi- 
nant list. 

HAMILTON FORMATION IN WISCONSIN. 

The Milwaukee fauna analyzed by Messrs. Teller and Monroe c 
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° 30 7 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 to a 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 York a 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 bj 7 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 





19 


6 


20 





18 





15 





12 


o 


12 


1 


9 


3 


12 





9 


1 



24 

11) 
li) 
12 
9 
4 
9 
7 
7 
7 

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 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 ( t V 8 tt) °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 A 6 + 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. 
Regarding this point Prosser 6 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. V r ol. 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. 
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. 



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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 airead3 r 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 L T nadilla 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. 8 1 ! 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. W T hite. 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. 2SV m . (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. 

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