Bulletin No. 210 - . .- WV

Series C, Systematic Geology and Paleontoro|,y,;-61r .

DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. \VALCOTT, DIRECTOR

THE

CORRELATION OF GEOLOGICAL FAUNAS

A CONTRIBUTION'TO DEVONIAN PALEONTOLOGY

BY

HENRY SHALER WILLIAMS

WASHINGTON

GOVERNMENT PRINTING OFFICE

1903
C'W
CON T E NTS.

Pace.

INTRODUCTION __......_.-.-_._-_____...-..-...-.-._..-_-..--_..-..-----. 5

CHAPTER I. The principles of correlation ............ .................... 1.0

Importance of. correlation .............................. .^............ 10

Correlation division of the United States Geological Survey .. r ......... 10

Dual nomenclature .....---........-...--.---.--.-...----...-...------ 11

Definitions and nomenclature of fatinal paleontology...-..........-.-- 18

/A.nimal and plant aggregates..........--.........---.-..-.....-.--... 18

Zoological and botanical classification ............................. 15

Distribution and range....---.-------.----------.............-.-- 16

Geological faunas and their nomenclature .....-..............'.---..-. 20

Nomenclature of formations _______....._..__-._.____.._._._...---.-.. 27

Faunal aggregates..................................................... 28

CHAPTER II. The geological expression of faunal migrations. - ........ i... 88

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 .............................. 4.9

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 .-...-.i_..._._............,__ 52

Range values of the species.... .--.-----.--..--..-------...... 58

Cayuga Lake section......................................... 54

Eighteenmile Creek section ...................°............... 57

Construction of a standard list of the dominant species of the Tropidoleptus carinatus fauna __._.___..________._._-...___.__.______....__ 58

Effect of additional statistics....... .-...--.-.--..................-.... 02

Statistics based on analysis of the zones of the Livonia salt shaft...... 68.

Hamilton formation in Ontario, Canada ................................ 64

Hamilton formation in Michigan ................................< _..... 65

Hamilton formation in Wisconsin. ...........-._-.....-...... ......-.... 65

Hamilton formation in southern Illinois -._.--.-_....__...._______.._. 66

Sellersburg formation in Indiana....................................... 66

Roinney formation in western Maryland .................. ....^....... 67

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...._ .......................................'...... 78

Productella speciosa fauna ..............................^........ 76

Immigrant species of Ithaca formation ............................. 78

Mutation and correlation of the faunas. '.............................. 8.1

3
4 .CONTENTS.

CHAPTER III Continued. .Page.

Chemung formation and its fauna.-....._.... .-.-..-.--.......--.--- ... 82

Spirifer disjunctus fauna ._-.._-.._..__._._ j.__... ........-.---... 83

Recurrence of the Tropidoleptus fauna in the epoch of the Spirifer disjunctus 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 ....'..................:.................... .L...'. 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 " faunule " ................. 131

.The bionic time scale .. ........-.---....._....-..-'--'--..-......:.-... 132

BIBLIOGRAPHY. ....--..-...-.......-.....-....-...--.-.-.--...-...-.-.... 135

INDEX ..................................'..............--.-........-...... 141

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

PLATE I. Comparative chart.of the Middle and Upper Devonian formations -

of Ohio, Pennsylvania, and New York ........................ 120
THE CORRELATION OF GEOLOGICAL FAUNAS.

By HENRY SHALER WILLIAMS.

INTRODUCTION.

In the year 1881 I began a series of investigations for the purpose 

of discovering the laws which determine the association of fossils in 

faunal aggregates and their modifications in relation to geographical 

distribution and to vertical succession, in order to apply those laws 

as guides to the correlation and classification of geological formations. 

While these investigations have been in progress many other workers 

have joined in the search. Many statistics have been gathered, and 

observations have been extended over a Avide 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 the idea of 

sharp distinction between formations, each of which had a characteristic set of " Leitfossilien." The prevalence of this latter view dominated 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 that, in order to 

learn how the modification of species has actually taken place, the
6 CORRELATION OF GEOLOGICAL FAUNAS. [BUM,. 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 Chemuug, a 

number of zones filled with separate fannules ft were discovered, some 

of which were entirely different from others in the series, but the 

order of their succession was readity distinguished in each of the 

rock sections for miles about. This integrity of the faunules in geographical 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 formation 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 general geological column was constructed of a single series of superimposed formations, diversity of fossil contents standing for difference 

of formations. Each formation was thus forced to take some particular place in a single geological column.

As knowledge of the faunas increased, the failure to establish the

exact identity of & 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 envia The term " f aunule'' is here and in the following pages used to distinguish an aggregate of fossils associated in a single stratum or zone from the total aggregate of species (the fauna) distributed 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 abundance. The association in the faunule is supposed to be an expression of the temporary adjiistment 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 several 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 more 

or less variation of composition, due to local and temporary conditions. (See page' 131.)
WILLIAMS.] 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 Carboniferous 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 estuary or fresh-water beds 

containing an entirely different fauna was established. But, in general, in the lesser cases, where faunas of the same kind of organisms 

are concerned, it has been the prevailing practice of geologists everywhere 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 leading to false conceptions of geological history that the investigations 

here described were begun. But the difficulties in the way of demonstrating 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 contradiction to say that two formations with unlike faunas may be identical 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 equivalency 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, Pennsylvania, and eastern Ohio. It was proposed to make a series of sections cutting through the same general part of the geological column, 

at intervals of about 50 miles, extending eastward as far as the Hudson 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, 1ST. Y., in 1881-82. Minute study of each section was to be made; the fossils were to be collected from each fossiiiferous /one, the position of which was to be carefully noted, and 

the fannules so collected were to b'e 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 certainty. The work was begun privately- in Cornell University, but the 

necessity of transgressing State lines led to the association of the 

university with the United States Geological Survey, by whose official
8 COEEELATIOISI OF GEOLOGICAL FAUNAS. [sum,. 210.

sanction and financial assistance the necessarily slow process of accumulating the statistics has proceeded. At the outset Major Powell, 

then Director of the Survey, and Mr. Charles D. Walcott, then in 

charge of Paleozoic paleontology, gave their valued encouragement. 

The task was a large one, but its importance was also great. A single person could not expect in a lifetime to execute the whole work 

required to solve the problem, and therefore graduate students at Cornell University, and later at Yale, seeking practice in geological investigation, 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 Science. 01 

At that time ten of the sections had .been run, viz: Cuyahoga, Ohio; 

Painesville, Ohio; Girard, Pennsylvania; Chautauqua, New YorkPennsylvania; Genesee, New York-Pennsylvania; Canandaigua, Now 

York; Cayuga, NOAV York; Tioughnioga, New York; Chenango, New 

York; Unadilla, New York. The fossils were collected from the 

separate fauimles, and certain general conclusions were then evident. 

Since then Messrs. Prosser, Clarke, Darton, and others have pushed 

the sections farther east, and they have bee,n extended, with the aid 

of Messrs. Van Ingen, Weller, and Kindle, into Missouri, Arkaiisas, 

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 part of the field have been carried much further than others, but the undertaking lias 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 elaborating 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

it On the classiflcatioll of the Upper Devonian: Proc. Ain. Assoc. Adv. Sci., Vol. XXXIV, 1886, 

pp. 222-234.
wiT,r,TAMS.] INTKODUCTION. 9

referred to for the names of those to whom .1 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 relationship 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 Ingeii, 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 COBRELATIOISr.

IMPORTANCE OF CORRELATION.

In the Mnth 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 separated 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 recognized 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 di fferent students assign different limits to the possibilities 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 knowledge bearing 011 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, Ball 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 correlation 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. Kept. U. S. Geol. Survey, 1889, p. 1.6.
WILLIAMS.] PRINCIPLES OF CORRELATION. 11 

DUAL NOMENCLATURE.

It was while acting as a member of the American committee which 

was engaged in preparing reports on the American systems for the 

Inter-national 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 formational 

boundaries which were established on lithological and stratigraphical 

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 designations 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 distinctions, 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 stratigrapllic geologist 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 investigations 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 stratigraphic to so great 

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 COEEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

ually in various places and in different ways. The same experience is found, to a 

greater or less extent, as any local terras are extended from any of the States into 

those contiguous. This plainly shows that unless there be allowed great freedom, 

to vary from the scheme adopted for stratigraphic designations, any nomenclature 

which the committee or the International Congress may adopt will be but a shortlived experiment.

It will obviate all this confusion if * * * one set of names be chosen for the 

lithplogical 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 denned.«

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

As surveys have advanced, and as the field of geological correlation 

has gone beyond local and national boundaries, the task of establishing correlations has made the necessity of a dual nomenclature 

more imperative. Correlations between widely separated regions are 

no\v 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 lithologically defined formation from the biologically defined fauna (which 

may or may not be limited in its range by the boundaries of the formation) can be supplied only through discrimination of the characteristics 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 discriminated, 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 fossil fauna will then become, as it is now partially recognized to be, the 

definite means of determining the time relations of geological formations. 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 b}7 the abundance of the facts already gathered 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

"Compte Reiichi Coiigres Geologique International, fourth session, 1888, A 91.

 6 On dual nomenclature in geological classification, by H. S. Williams: Jour. Geol., Vol.11, p. 145.
WILLIAMS.] PRINCIPLES OF CORRELATION. 13

the Hamilton formation have made it possible to treat the facts concerning it with a degree of precision that would not be possible in considering 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 Hamilton 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 history, 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 succession 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 pertaining to the relations which living organisms bear to their environment 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 correlated by their contained fossils'? The fact of correlation, is taken for 

granted; but the questions are, Wherein does correlation consist? 

What 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 preservation, 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 

whieh the particular aggregations are made.

The zoologist associates organisms on the basis of their morphological 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 characters 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 associated because of their genetic affinity i. e., descent from common 

parents; but we are now accustomed to recognize community of characters, 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 relation ship 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 affinity. 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 determine 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 inhabiting 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 likeness 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.
WTLMAMS.] ANIMAL AND PLANT AGGREGATES. 15

He speaks of Paleozoic faunas, Carboniferous floras, the fauna of the 

Trenton or of the Cambrian or of the Eocene.. The basis of aggregation 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 geological range of the organisms. The Eocene fauna includes all the animals, 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 differentlithological kinds, outcropping 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 environment. 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 formations 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 taxonoinic 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 COBKELATION 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 individual 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 Pliacops 

bufo were repeated without noticeable and permanent modifications 

during that period of time. We are not dealing with the biological 

aggregate, a taxonoinic 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 coine to mean, in scientific usage, an aggregate of animals 

of different kinds structurally, associated on the basis of some conditions existing outside the animals themselves. These conditions may 

be kind of element, as air, water, or land inhabited; place, as country, 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 distribution 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}7^ 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 "Atrypareticularis 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 Hard ing sandstone of 

Canyon, Colo., associated with a Trenton limestone invertebrate fauna'.

In order to discuss the problems of the time relations of organisms 

it is necessary to use the terms range and distribution to refer respectively to geological and. geographical space, and to note that the facts 

concerning the range of species and genera are stated in terms signifying 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 discrimination of the faunas, a method which is neither geographical nor geological, 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 evolution 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 section extending over a range of many hundreds of feet. These facts 

lead to the discrimination of the idea of variation and to the application 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 the safiie that' extinction 

of the race does not result.

In treating of the relations of organigms to time and of their evoluBull. 210 03 2
18 COKEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

tional history, it becomes necessary to notice the fact that each individual organism expresses the characters by which the taxonomic 

divisions of all ranks are denned. 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 category, not a living body.

The fact in the case is that individuals live, developing the characters 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 sedimentation 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 only 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 correlations 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 Avhich are of specific rank at one time in the 

history of a race cannot take generic rank in another part of the history. 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
WILLIAMS.] ANIMAL AND PLANT AGGBEGATES. 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 determines whether it be 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 necessary 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 correlation 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 taxonomic aggregates based on genetic affinities or as aggregates associated 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 differing from them no more than they differ from one another, but must consider the descendants which do differ, and the length of time during 

wliicli generation continues in the race with retention of the specific 

characters. The idea of continuity of race is an element in the geological 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 paleontologist has to extend this idea to include also the length of tim,e through 

ivhich the fauna persists 'without loss of the characters essential to the 

fauna.

Thus the paleontologist is not only forced to consider the time relations 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 distinguished.

A living species may be classified by its taxonomic characters and be
20 COEEELATION 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 discrimination 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 f ormational name to apply 

to the fauna, any 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. Whatever specimens have come from rocks classified as the Hamilton formation, 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 cpllector 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 fossiUferous zone may be coextensive with a formation vertically in one
WITATAMS.] GEOLOGICAL FAUNAS AND THEIR NOMENCLATURE. 2l

section, while another exposure of the same formation maybe broken 

up into several fossiliferous and barren /ones;, 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 necessary to note and 

record their place in the vertical section of strata making the formation. This is indicated most conveniently by measuring distance 

from bottom or top of the formation. This strati graphical position 

of the fossiliferous zone in the section of the geological formation is 

its horizon. r . '

A fossiliferons 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 fossiliferons 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 which the fossils prevail increases or 

decreases in the section.

A fossiliferons 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 fbssils than are 

its loAver or upper portions. Species which are proportionately dominant 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 fossiliferous or not, the berms lied ovband or stratum are used.

In this connection it is important to note that in ordinary sedimentary 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
S2 CORKELATIOtf OF GEOLOGICAL FAUNAS. [BUM,. 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 substance, 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 continuity or discontinuity of the zone: Continuity and discontinuity 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 physical formation and is not a fauna or a flora; the term connotes the 

geological position occupied by the fauna, as the term province connotes 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 geographical 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 conceivable, therefore, that the lapse of time represented by the presence in 

the strata of the species of the same continuous fauna may be nonsynchronousfor two sections not mo.ny 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 occupied 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
WTTATAMS.] GEOLOGICAL FAUNAS AND THEIR 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 ormoment 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 l>y 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 habitation, 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, an A continuity to mean that the stratigraphical horizon of a zone or formation is the same, the conclusion which has been 

reached may be expressed by saying that faunal equivalency does not 

necessarily conform to forrnational continuity, except for areas that 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 interpreted into 

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 stratigraphical 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 whi^h. 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 time 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 separated by barren or nearly barren zones. This fact is itself an evidence
24 CORRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

of migration; since a recurrence of the same fossils in successive 

zones can be rationally interpreted only on the.supposition that during the sedimentation of the barren strata the successors of the lower 

fossils and the ancestors of tliose 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 ascertain 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 fpssiliferous stratum is discovered on ascending a stratigraphical section, the paleontological observer stops and samples 

the stratum. The fossils thus gathered constitute a faunule. The 

faunule may be found to extend upward for several inches, or possibly 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 prevailing 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 lias been ascertained that these slight temporary incursions 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 collections come to be more minutely studied in the laboratoiy. The position 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 position 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 fossiliferous 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 fossiliferous zones 

recognizable in the separate sections examined. As an actually continuous section vertically is more satisfactory in faunal 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 forin of the fossils, 

tliat genetic kinship of faunules is traced.

By taking note of these characteristics of the faunules over territories several hundred miles in extent, and ranging through the middle and upper formations of the Devonian system, it has been possible 

to formulate several valuable rules for the discrimination and interpretation of fossil faunas.

Faunules of the same formation, located together in the same general 

region, are more closely alike in constitution and proportionate abundance 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 abundance of the species constituting the faunules.

AHhough 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 maybe 

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. [BUI.L.SIO.

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 modified, 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 spe'cies 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 dominance. It is to catch this replacement of the old fauna by a new one 

that the observer should watch with care the thin occasional intercalated beds containing species either wholly or in part diffei^ent from 

the prevailing fauna.

It has been often observed that the first traces of the new overlying fauna are to be detected almost pure in such little zones occurring 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 sediments 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 continuous 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." In this paper definitions tending to clarify 

tliinking in these directions are given. In another .paper, 6 read 

before the Connecticut Academy, February 12, 1902, 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 geological 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, limestone, 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 thorn from bottom 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 firstdescribed geographical outcrops. These names, are generally geographical terms.

'They are classified primarily on the basis of their observed order of 

succession, and secondarily on the basis of their supposed equivalence 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-formations; 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. 570-585. 

''Fossil faunas and their use in correlating geological formations: Ani. Jour. Sci., 4th series, 

Vol. XIII, pp. 417-432.
28 CORRELATION OF GEOLOGICAL FAUNAS. [BUT,L. 210.

The geologist is liable to regard fossils, in determination of correlation, as of the same order as minerals (viz, chondrodite) or petrographical 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 without noting its relation to some fossil-bearing rock.

In dealing with formations, therefore, whenever fossils are brought 

in, a new body 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 geological 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 ft 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 stratigraphical 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 Geologique," 6 by distinguishing separate ufacies"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 differentes sortes de formations, sedimentaires ou autres, qui peuvent s'etre .produites simultanettCompte Rendu Congrds G6ol. Internat., third session, Berlin, 1888, p. 322. 

bCompte Rendu Congr6s Qeol. Internat., sixth session, Zurich, 1894, p. 519.
WILLIAMS.] FAUNAL AGGREGATES. 29

merit, d un moment quelconque des t&mps geologiques, comme cela se 

passe 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 equivalency 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 establishment 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 successive 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 formations are distinguished.

What takes place with the living organisms during the transition 

of one formation to another has not been thoroughly observed or discussed. 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 naturally 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

. cit., p. 588,
30 COEEELATION 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 metropolis may shift. The composition of the fauna may be 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. denned 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 

applying 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 geographical area or thickness of strata occupied by the fossil remains of 

the once living races of organisms. An individual specimen of a species 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 duration represented b}^ formational systems. Nevertheless, an approximation to those formational divisions which have been found convenient in actual usage is presented by the life periods of species,

genera, and orders of marine organisms, as has been shown by a tentative scheme of classification on a bionic basis, ffl 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, Asaplius, 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, disjunctus, 

or cameratus 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.

c Jour. Geoh, Vol. IX, p. 587. See also p. 133 of this bulletin,
WILLIAMS.] FAUNAL AGGEEGATE8. 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 designation for a division of geological time, and thus one is enabled to 

speak of geochron as the time duration expressed by formations, and 

Inochron as the duration expressed by the life history of organisms.

A definite and independent value (i. e., independent of the formation 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 T&eraera was to be measured by the endurance 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 would 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 migrating species into the midst of a native fauna before the shifting was 

general,
32 OOERELATIOlSr OF GEOLOGICAL FAUNAS. [BULL. 210.

Such movements of faunas may be assumed to have been more frequent 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 shifting 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 naturalists for centuries. It was a problem of geographical, distribution, 

more than anything else, which suggested to Darwin the accounting 

for difference.in^ organisms by evolution through the agency of natural 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." 68

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 bottom to top by the same fauna; Avhile shales and sandstones, indicating 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 environment, then either the changes of environment coincident with change 

of sediments must be the occasion of the modification of the organisms 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

f'Lifo and Letters, Vol. II, p. 338, New York, D. Appleton & Co., 1898.

Bull. 210 03 3 83
34 OOEEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

the rapid changes of environment faunas have shifted their habitation, the conclusion would be that there was a slight acceleration in 

evolution with the readjustment of the faunas, and that the shiftiugs, 

when of a general nature, would result in modifications of the faunas 

which would serve as means of a closer correlation of the time relations of geological events, not only in one quarter, but quite around 

the globe. While 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 observing 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, however, 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 containing 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 unlikeness of species is evidence of a different age for the formations holding 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 FATJNAL 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 

different 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 different facies of the fauna of the same period and the successive 'mutations of the fauna consequent upon geological succession. To put 

this in a wordj 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 concerning 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, irrespective 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 possibilities, 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 extremely 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 f aunal 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 COEEELATION 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 existing1 conditions of environment. Such movement of the earth's surface, resulting in the gtographical 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 b.e 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 contemplates 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 he 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 within 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 principle 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 fossils 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 formations 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 MIGEAT10N. 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 correlated 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 geographical 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 particular 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 combined. 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 continued at one point after it had ceased and was replaced by the deposition 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 regarding 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 Chemung formation is known to follow (to lie above) the Hamilton formation 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 characteristic Chemung fossils.

These two sets of facts the formations and the faunas must therefore 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 does not stand for the whole of any particular period or interval 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 are 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 stratigraphical 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 stratigraphical 

sequence, hence stratigraphical 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 geographically, and may thus cause confusion in the classification and correlation 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 EXPRESSION" OF FAUNAL MIGRATION. 30

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 necessary 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 uiy 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 comparatively studied for a few hundred miles across the field of its distribution. 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 without any doubt as to their stratigraphical correlations. The invest!-, 

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 stratigraphically 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 species 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. 05 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 they 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

n See On the Southern Devonian formations: Am. Jour. Sci., 4th series, Vol. Ill, 1807, pp. 393-403.
40 CORRELATION OF GEOLOGICAL FAUN"AS. [BULL. 210.

strongly contrasted with the other) has come from outside the particular 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 be 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 prohibiting 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 movement 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 environmental conditions are forcibly modified than during the periods, however 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 sufficient to lead to regarding the stage as the same continues through a
WILLIAMS.] GEOLOGICAL EXPRESSION OB1 FATTNAL MIGRATION. 41

series of sediments, the individual species suffer but slight change, 

and this has been observed through hundreds of feet of limestones, 

running 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 themselves. Darwin has spoken of such variation as "spontaneous variation;" that is, variation which is not accounted for on the principle 

of natural selection, but which is presumed to be present before natural 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 distribution, 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.

FAUNAE DISSECTION OF MIDDLE AND UPPER DEVONIAN 

OF THE NEW YORK PROVINCE.

The collecting of statistics to illustrate the laws, of fauna! 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 particular investigations were begun, and partly because for a number 

of years definite attention has been given to gathering and recording 

the exact statistics needed for the purpose of solving practical difficulties 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 Catskill group does not settle it. Neither does the expansion of the Chemung formation 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 b'ear to one another that.the difficulty is

to be met. This is to be attained, not by clinging to any sharp limits of a stratigraphical or a lithological nature, or to any absolute division between one formation 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 occurrence. By this method a scale marking the chronological sequence in the life history 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 disintegrating 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 fundamental assumption that identity of fossils is sufficient evidence of

«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 "Chemuiig 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 Chemurig 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. 6

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 different 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 distinction between a lithological formation and a fossil fauna.

It is now possible to state that the Tropidoleptus fauna of the Hamilton 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 formation and in the Geiiesee Valley by a portion of the Portage formation.

a 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. 603.
44 COEEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

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 reel sedimentation, which, therefore, was easily discerned in the 

field by the stratigraphicar 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. They 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 by 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 modification 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 equilibrium.

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

a Dual nomenclature in geological classification: Jour. Geol., Vol. II, 1894, pp. 145-160.
WILLIAMS.] FAUNAE 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 investigations 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 developed.

INTRODUCTION OF A FAUNAL CLASSIFICATION OF THE - 

DEVONIAN SYSTEM.

Bulletin No. 3 of the U. S. Geological Survey, On the Fossil Faunas 

of the Upper Devonian along the Meridian of 76° 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. G-enesee slate fauna.

2. Portage group; 1,800 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. Secondary faunas of the Portage group were recognized and named as follows:

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

2. Spirifer Isevis fauna (sec. 110.1, p, 12).

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

3. Lingula faiina (Ithaca shale. No. G, 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 rnesicostalis zone (1102 B, 1107, 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 and sent to
46 COKBELATION 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 privately 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 Genese'e 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 Geuesee 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 County, 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 ISTo. 41 the faunal zones 

recognized were as follows:

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

2. Cardiola 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. Plat-pebble conglomerate; Palseanatina typa (sec. 486).'

10. Ferruginous sandstones; Rnynchonella allegariia (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 Spirifer disjunctus fauna, and the Ortliis 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 particular conditions of environment or habitat, which, locally, had definite 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 1886, iii 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 

from Newberry's typical Cuyahoga section at Cleveland, Ohio, to 

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 recognized :

A. Hamilton fauna and its direct successors.

B. Black shale faiina. .

C. Portage fauna.

D. Chenmng fauna.

E. Flat pebble conglomerate fauna.

F. Catskill faitna and flora.

G-. Waverly fauna.

H. Oleaii 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 halting places or stages in the evolution of the fauna, they are not full, 

but rather partial, expressions of the general fauna, reflecting particularly 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 recognized, as first reported in 1886, as follows:

A 1. Paracyclas lirata stage or faunule.

A 2. Spirifera Isevis stage or faunule.

A 3. Stropheodonta mucronata stage or faunule.

A 4. A try pa reticularis stage or faunule.

A 5. Leiorhynchus globtiliforme stage or faunule.

A 6. Tropidoleptus carinatus stage or faunule.

A 7. Spirifer mesistrialis stage or faunule.

A.6-)-. 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 spattilata 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.

aFroc. Ain. Assoc. Adv. Sci., Vol. XXXIV, pp. 222-234.
48 COEBELATION OF GEOLOGICAL FAUNAS. .[BULL. 210.

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

C 1. Cephalopod stage or faunule, G-oniatites and large Cardiadse. 

C 2. Lamellibranch stage. Cardiola speciosa. 

C 3. Portage sandstone, a generally barren zone.

The Cheniung fauna (D), or Spirifer disjunctus fauna, was analyzed 

into:

D 1. Orthis tioga stage or faunule.

D 2. Stropheodonta (Cayuta) mncronata stage.

D 8. Athyris angelica stage.

D 4. Rhynchonella contracta stage.

D 5. Spirifer altus fauna.

The flat-pebble conglomerate (E), as illustrated by the Wolf Creek 

conglomerate (sec. 483 C, p. 86), contains:

E. Palaeanatina 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 Holoptychius and other fish remains, characteristic plants, and the Amnigenia 

catskillensis, 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 188G 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 discussing the faunas of the whole continent and in comparison with 

the faunas of the world.

The fauna of the typical Hamilton formation (A) may be appropriately 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 Cardiola speciosa fauna. Although, as Hall has shown, this is not a
WILLIAMS.] FAUNAL DISSECTION OF THE DEVONIAN. 49.

Cardiola, as strictly interpreted, and the name Glyptocardia was pro1 

posed as anew generic name in 1885 a to take its place, the fact that 

in Europe as Avell 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 discussing this species (G-lyptocardia (Cardiola) speciosa Hall): 6

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 

1886 ° 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. Barton, 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 rarity and in terms of frequency 

of appearance in successive stratigraphical zones or at distributed geographical 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 generalizations 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-

«Palaeontology New York, Vol. V, Pt. I, Larnellibranchiata, II, text, p. xxxv.

& Ibid., pp. 426-427.

o Classification of Upper Devonian: Proc. Ana. Assoc. Adv. Sci., Vol. XXXIV.

Bull. 210 03 4
50 CORRELATION OF GEOLOGICAL FAUNAS. [BUUL. 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 development of the continent.

The faunas specifically examined are:

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

Tropidoleptus carinatus fauna.

2. Fauna of the Ithaca formation, which may be called the Productella ^speciosa fauna.

3. Fauna of the Cliemung formation, designated the Spirifer disjunctus fauna.

Other faunas and subfannas will be named as they are taken up, but 

the statistics of these three faunas are ample and they are of a like 

facies, fl 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 Hamilton group7 includes the Mareellus 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 faunally as 

a separate formation. Faunally, the series of sediments, as they are 

exhibited in central New York (beginning at the top of the Onondaga 

(Corniferous) limestone and terminating at the base of the Tully limestone), 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 

r Onondaga limestone and the base of the Tully limestone, when these 

'^ are present, will be considered as belonging typically to the Tropi- 

~r doleptus fauna. But the published lists are, on the one hand, too full, 

1 because they contain all the species which have been reported from 

the Hamilton group or formation, however that formation has been 

,A.<wV-<.- identified; and, on the other hand, they are not sufficient for the 

\ot\Ato-W^purposes of this paper, because locality and place in the formation

*{

*"

&<a_J<

^

J^ v

-< 1

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

aln a paper read before the Geological Society of^America after the present bulletin had gone 

^ to press I proposed the term liomeotopic to express this likeness of facies of these faunas. See 

^. Bull. Geol. Soc. Am., Vol. XIV, 1903. ,

#:S#L.^& i

" L " // ; ""' /V.* / i . , . ' t tt '- V ' -^- v V vi

/.

J4

^ K- v

/c [^ P., C. I .JL rvf.AvM Mv.x tA
WILLIAMS.] FAUNAL DISSECTION OF THE DEVONIAN. 51

large set of local faimules, prepared in determining, by the fossils, 

the area! distribution of the formation, has been examined, and only 

those faimnles 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 thefannules of each 

f ossilif erous /one from bottom to top of a typical section of the formation was examined, and the proportionate abundance of species for 

each zone and the range of the species were thus ascertained.

TKOPIDOLEPTUS CARINATUS FAUNA AS EXPRESSED IN EASTERN COUNTIES OF NEW YORK AND PENNSYLVANIA.

An examination of the fauna!, lists prepared by Prof. C. S. Prosser" 

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 MadiT 

son, Chenango, Brooine, 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 carinatus fauna: Species occurring moat frequently in 

the Hamilton formation east of Cayuga Lake.

[Dominant distributional frequency list for eastern New York.]

*

1. Spirifer pennatus ....................

2. Tropidoleptus carinatus _-.-.__._.....

4. Clionetes coronatus. . -..--..- ..........

5. Paljeoneilo constricta ................

7. Ambocoelia umbonata ................

9. N. oblongatus ............_....-......

10. Nucula corbulif ormis ................

11. Athyris spiriferoides ..... ....;.......

12. Phacops rana ................. -._...

Number of 

localities 

at which 

found.

113

89

59

57

56

42

40

38

35

33

32

32

Number of 

groups of 

localities.

30

27

28

26

27

23

22

22

21

17

24

1.8

Abundant.

. 26-

22

11

10

2

4

4

1

1

4

 2

1

Common.

33

30

15

16

5

8

8

7

3

8

5

4

 « The classification and distribution of the Hamilton and Chernung 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 Cheinung series of central and eastern 

New York: Seventeenth Ann. Rept. State Geologist New York, Part II, 1900, pp. C7-327.

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. [HULL. 210.

The total number of species cited in faunule lists from 146 localities, 

divisible into 30 groups of localities, in eastern New York and Pennsylvania is 172. In addition to these positive identifications, 15 

species are named with a query, and 11 genera not positively identified 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 146 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 146 localities, 

nearly 22 per cent of the whole. When the distribution is based on 

groups of five localities the frequency reaches 17 out of 30 times, or 

nearly 59 per ceni, 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 many 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.

FKEQUENCY 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 prominence of the first four species of the list.

The first species is cited as abundant 26 times and common 33 times; 

or for 59 times out of the 113 records it is at least common. This species is Spirifer (mucronatus) 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.] FAUHAL DISSECTION OF THE DEVONIAN. 53

The next two species, Spirifer granulosus and Chonetes coronatus, 

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 56 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 species of the Hamilton formation of this region (so far as reported in 

these statistics) are both less frequent and less abundant in the 

faunnles 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 following 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 identifications 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 maybe 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 province 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 importance 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 geographical 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 endurance 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 conception of a fossil fauna, it is necessary 

to ascertain what were the dominant species. Dominance is a relative 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 imiy 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 geologically as it is able to continue breeding and living, at least in a 

metropolis of distribution whose conditions remain approximately con 

stant. A fauna once broken up in its biological equilibrium as a 

fauna must come to an end, hoAvever long thereafter individual species 

may persist.

In order to apply these principles to the determination of the essential characteristics of the Tropidolepius fauna, two kinds of statistics 

were needed:

(1) Statistics to show the dominant species of the fauna in its geographical 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. H. F. Cleland, already well equipped by his previous 

biological training, to make an exhaustive anatysis of the Hamilton

<* Heterotopic is proposed to express this adjustment to diverse conditions of environment. 

Bull. Geol. Soc. 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 dissection of the formation from bottom to top. The fannules were collected 

from 70 zones of the 1,224 feet 2' 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 aggregates represented in the series. These were spoken of in his paper as 

zones, and marked by letters from A to Y. The species were distributed quite generally throughout the several zones; but each zone 

sometimes a few feet thick and occasionally 10 01' 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 geological time thefaunides of such zones as Cleland lias analyzed and 

listed may be called I/ionic units of the first order; the time represented by the continuance of the particular faunal equilibrium of such 

a unit may be called a liemera, applying the term nearly in the original 

sense of Buckman,6 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 conception 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.

o A study of the Hamilton formation of the Caynga Lake section in central New York, by 

H. F. Cleland: Bull. U. S. Geol. Survey No. 200,1903.

''This is Prosser's estimate of thickness. Cleland estimates the total thickness of Hamilton 

to bo 1,100 feet (Bnll. 200, p. 90).

eS. S. Buckman, Quart. Jour. Geol. Soc., November, 1893, Vol. XLIX, p. 481.
56 COKKELATION 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.]

1. Tropidoleptus carinatus. __....

3. Palseoneilo constricta -._.---.-

4. Spirif er pennatus ..--.--.--.-,

5. Phacops rana. ................

6. Cryphaeus booth! .............

7. Nucula corbuliformis. ........

Number of 

zones 

in 

which, 

found.

21

21

21

20

20

20

19

8. Chonetes mucronattis - . .

10. Nuculites triqueter ..........

11. Modiella pygmaea ...........

13. Stropheodonta perplana .....

-14. Nuculites oblongatus ........

Num- c ber of 

zones 

in 

which 

found.

18

17

17

16

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, Amboccdia umbonata, Palczoneilo constricta, Spirif er (mucronatus} pennatus, and Phacops rana; the 

remaining 7 of the dominant list are found in the Cayuga Lake section, but they are not among the more widely 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.

Nucula bellistriata does not appear in the 6 lower zones at Cayuga

Lake, but is seen in 8. of the zones above.

Cryphceus boothi, which appears in 20 of the 25 zones of the Cayuga 

Lake section, is not common in the eastern sections. It was discovered in several sections about Smyrna and Sherburne, once at Summit, awd 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.

Modielia pygmc&a 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 fairty common eastward, 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.

formation at Cayuga Lake, the dominant list already selected presents 

the most characteristic species 011 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 faun tiles as they occur in the section of the 

Hamilton rocks at Eighteenmile Creek. a

Mr. Grabau madie 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 identified with any 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 frequently in 

the Hamilton formation at Eighteenmile Creek.

[Dominant range frequency list for Eigkteeuinile Creek.]

\ . Spirif er pennatus ....-....-

'6. Chonetes lepidus ...........

6. Chonetes scitulus ...........

Number 

of zones 

in which 

found.

28

26

21

on

18

18

7. Primitiopsis punctilifera . .

8. Stropheodonta perplana . . .

9. Orthothetes arctistriattis ..

10. Bhipidomella varraxenri.-.

1 1 . Pr odtictella spirralicosta . . .

12. Cryphaeus booth! .........

Number 

of zones 

in which 

found.

18

17

17

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 4 are among 

the first 5 showing most frequent occurrence in the zones of the formation 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.

o Tho 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, 1898, pp. 231-339.
58 COEEELA.TION OF GEOLOGICAL FAUNAS. [BULL. 210.

TABLE Ilia. Dominant eastern species not dominant in the Eighteenmile Creek

section. 

Spirifer granulostis -...-.-----.------.---.-.-----......,...................... 10

Chonetes coronafrus -:-. --.._____.-----.---.-.._._.__._._____.__.____.___.___ 6

Palaeoneilo constricta...... ....-.-.-..-...-....-......1.................... 4

Nticnlites triqneter ......... ...............,......'.......................... 1

Nucula bellistriata .........................^^...............................f 0

Nucula corbuKf ormis ....... ............................................ .... 0

There are also several species in the range list of Eighteenmile 

Creek not in the dominant distributional list of eastern New York. 

They are:

TABLE Illb. Dominant Eighteenmile Creek species not dominant in the eastern

New York region.

.

146 faunules.

11

17

0

15 Crvphaeus booth! . ........ ....

146 faunules.

12

17

0

' 17

The numbers in this list indicate the number of times the species 

is recorded among the 146 faunules 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 Tropidoleptus fauna, derived in two ways first, on the basis of frequency of 

occurrence in geographical distribution for a region in which the formation 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
Wl LLIAMS.'J FAUNAL DISSECTION OF THE DEVONIAN. 59

by the same man are, naturally, more likely to furnish correct comparative 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 several modes of measuring the bionic values of the species the average 

may 1)6 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 carinaius 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 figures 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 vertical column of the Cayiiga 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 number 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.

Spirif er pennatns ............

Tropidoleptus carinatns ......

Chonetes coronatus ..........

Palaeoneilo constricta ........

Nucula bellistriata . ..........

A inbocoelia tiinbonarta ........

Nuculites triqueter. ..........

Nucula cor bull f'oriiiis ... ....

Athvris spiriferoides ..........

Phacops rana ................

1.

Eastern 

New 

York.

Per cent.

78

60

40

40

40

29

28

28

24

23

22

22

2. . Cayuga 

Lake.

Per cent.

80

84

40

52

84

32

84

68

64

76

68

80

8.

Eighteenmile 

Creek.

Per cent.

80

23

29

17

12

. 0

51

3

0

60

74

4. 

Ontario, 

Canada.

*

*

*

#

*

*

*

&

5. 

Total.

Per cent.

, 238

167

109

109

136

61

163

99

94

99

150

176

G. 

Rank of 

species.

1

3

7

8

6

19

4

9

11

10

5

2
60 COKKELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

In this table columns 1, 2, 3 express, approximately, in percentages, the facts shown in Tables I, II, and III; column 4 indicates 

the species which are recorded in the fauna of Ontario, Canada; 0 

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

6. Palseoneilo constricta. -._--.

Per cent 

of bionic 

value.

79.

58

56

. 54

47

45

7. Spirifer granulosus ..--.-.

8. Chonetes coronatus --_.--_

9. Nuculites triqueter .......

12. Nucula bellistriata .......

Per cent 

of bionic 

value.

36

36

33

33

31

20

The figures to the right in this list express in percentage the approximate bionic value for each of the species as. obtained from the statistics before us. It will be seen that there are 10 species which have 

a bionic value in this fauna of 33 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 maybe 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 Hamilton 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 Canadian Palaeontology, 1885-1898, Vol. I, Part V, pp. 361-436, Pis. XLVII1-L.
WILLIAMS.] FAUNAL DISSECTION OF THE DEVONIAN. 61

recurrence frequency, is to exalt the rank of the species Arriboccelia 

umbonata,' Atliyris 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 frequency in Madison and Chenango counties, and again in Greene, 

Ulster, and Orange counties, and across the State line in Pennsylvania, would 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 Hamilton 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 distinct 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 lithological 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 Tropidoleptus fauna still appear. These species continue after the introduction 

of Spirifer mesicostalis 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 

Cheinung had ar-rived in central New York. In the extreme eastern 

counties this species is not certainly reported} but many of its associates in the western part of the basin are introduced before the entire
62 COERELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

disappearance of the Tropidolepius fauna from the eastern corner of 

the basin.

On following these faunas westward it is found that the Tropidoleptus 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 an$ Delaware counties, 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 generic names are cited without identification of the species observed. 

The 12 more .common species of the 37 faunules are named in 

Table VI.

TABLE VI. Tropidoleptufi fauna: Dominant species of the Hamilton formation

of the Unadilla region.

* 1. Amboccelia umbonata .---..._. 23

* 2. Tropidoleptus carinatus-.'-.--.. 20

* 3. Spirifer pennatus .............. 17

4. Paracyclaslirata_...... ....... 11

5. Leiorhynchus laura ............. 10

* 6. Nuculites oblongatus .--.-...... 13

* 7. N. triqueter .................. 9

* 8. Chonetes coronatus ........... 9

* 9. Spirifer granulosus ........... 7

* 10. Palasoneilo constricta ......... '7

11. Spirifer medialis.............. 7

12. Chonetes scitulus............. 7

It will be noted that 8 of these 12 species belong to the standard 

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 corbuliformis. 

N. bellistriata.

The dominant list for the Unadilla district contains four species not 

in the general dominant list, which are 

Paracyclas lirata. 

Leiorhynchus laura. 

Spirifer medialis. 

Chonetes scitulus.

a Forty-sixth Ann. Rept. New York State Museum, 1893, pp. 256-288.
WILLIAMS.] FAUNAL DISSECTION OK THE DEVONIAN. 63

If now we make a revised list by adding to the standard, list based 

on the M6 faunnles the new distributional values of:' all the species as 

they appear in the 37 Unadilla 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 lint of dominant specie* of the Ham- 

. ilton formation of eastern Neiu York and Pennsylvania, as expressed in 183 

faunules.

1. Spirifer pennatus .------.-..... 130

2. Tropidoleptus carinatus .......... 109

3. Spirifer grarralosus............. 66

4. Chonetes coronatus.............. 65

5. Amboccelia tiinbonata.......... 63

6. Palseoneilo constricta .......... 63

7. Nuculites oblongatus .......... 48

8. N. triqueter ................... 47

9. Nucula bellistriata............ 47

10. Phacops rana ................. 38

11. Athyris Spiriferoides .......... 36

12. Nucula corbuliforinis ......... 33

13. Leiorhynchus laura ........... 30

14. Paracyclas lirata............ . 29

15. Chonetes scitulus ............. 24

16. Stropheoclonta perplana ....... 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 standard 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 by Prosser in his paper on eastern Nev 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 Hamilton fauna.

Dr. Clarke has given an analysis of the species discovered in the 

 Livonia salt shaft/' 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 corbidiformis, 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 1C 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.

"Tho succession of the fossil faunas in the section of the Livonia salt shaft, by John M. Clarke: 

Thirteenth Ann. Kept. State Geologist New York, 1893, Vol. I, Geology, pp. 131-158.
64 COEEELATIOF OF GEOLOGICAL FAUNAS. [BULL. 210.

The species occurring the greater number of times in the 16 faunnles 

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

8. Bellerophon leda ............... 6

9. Actinopteria decussata ........ 6

10. Streptelasma rectum .......... 5

*11. Spirifer pennatus ..-.. ....... 5

12. Orbiculoidea media ........... 5

*13. Chonetes corpnatus.-.--..-.... 5

*14. Ambocoelia umbonata......... 5

Those of the standard list are marked with asterisks, and constitute 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 second) 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 common 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 Avere gathered 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, ffi include 8 of the standard list of 12 dominant species of the Tropidolepius 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 alphabetically, because the statistics regarding range or distributional frequency are not reported.

TABLE IX. Tropidoleptus fauna: Species of the standard lists of the Hamilton 

formation of New York State which are also reported from the Hamilton formation of Ontario, Canada^

* Ambocoelia 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.

oOn 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 Canadian 

Paleontology, 1885-1898, Vol. I, Part V, pp. 361-436, Pis. XLVIH-L.
WILLIAMS.] FAUNAL DISSECTION OF THE DEVONIAN. 65

The four species absent are 

Nuctila bellistriata. Nuculites oblongatus. 

N. corbuliformis. Paleeoneilo 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 Goelenterata 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 gathered from the lists prepared by C. Rominger/'

The occurrence of the following species is mentioned:

Spirifer (mucronatus) pennatus.

S. grarralosus.

Chonetes coronatus.

(Spirigera concentrica=). Athyris spiriferoides.

(Phacops bufo=) P. rana. i

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 dominant list.

HAMILTON FORMATION IN WISCONSIN.

The Milwaukee fauna analyzed by Messrs. Teller and Mouroe c 

contains the following species:

Phacops rana. 

Palseoneilo constvicta. 

Nucula corbuliformis. 

Spirifer pennatus.

Several other species of the common fauna of the Hamilton formation of eastern New York are also reported.

Here are enough of the representatives of the standard Tropidolepius 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. Gralmu; Kept. State Board of 

Geol. Surv. Midi., for 1901-2!

 - The fauna of the Devonian formation at Milwaukee, Wis.: Jour. Gool., 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,® 

which contains three of the standard representatives of the Tropidoleptus fauna, viz:

Chonetes coronatus. 

Phacops rana. 

Tropidoleptus.

Some of the less common species of the New York Hamilton formation are 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 intercontinental.basin from the south, and probably by a passage on the south 

side of the Ojfark island of Missouri. If this hypothesis be correct, 

the association of the more typical species of the fauna with Onondaga 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, Indiana, and Ohio, point the same way.

SELLERSBURG FORMATION IN INDIANA.

Recent investigation made by Dr. E. M. Kindle is revealing traces 

of the TrorjidoleptiLS fauna to'the west of the Cincinnati-Nashville 

ridge in central Indiana.

In a report-now preparing' for the press, Dr. Kindle gives the following 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.] FAUNAE DISSECTION OF THE DEVONIAN. 67

Sellersburg faunule, Lexington, Scott County, Ind. 

Chonetes yandellantis (abundant). 

Tropidoleptus carinattis (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 Jeffersonville 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 we 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 consult 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 OOEEELATION OF GEOLOGICAL FAUNAS. [BULL. 310. 

ABSENCE OF TROPIDOLEPTUS FAUNA IN OTHER REGIONS.

That the Tropidoleptus fauna is not represented in the Iowa formations 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 Tropidoleptus carinatus fauna! 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 locality must be regarded as directly connected.

POST-HAMILTON FORMATIONS AND THEIR FAUNAS IN NEW

YORK PROVINCE.

Having demonstrated the dominant characteristics of the fauna 

which is contained in the Ha'inilton 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 theTulty is not evident; and, where the evidence of those ordinarily 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 Hamilton formation was deposited, in which case the fauna existed prior to 

the beginning of that formation; second, unless evidence can be furnished of the destruction of the fauna at the.time of the deposition 

of the Tally limestone or the Genesee shale, there is no reason to 

believe that its integrity as a fauna was there suddenby 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
WII,T,TAMS.] FAUNAL DISSECTION OF THE DEVONIAN. 69

in which they 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 limestone and the Genesee shales are distinct formations and form a 

definite termination for the Hamilton formation.

It was pointed out in a later paper b that this zone was indicated by 

the first appearance in the New York section of Rliynchonella(Hypothyris) cuboides (=J?. venustuld 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 modification 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 disjimctus fauna) than with the 

Tropidoleptus fauna, and the conclusion was therefore reached that 

the Tully limestone was more naturally associated faun ally 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 ManitobaMackenzie River seas of Devonian time.

In the Cayuga Lake-Ithaca section, above the Tully came the black 

Genesee shale with its Lingula spatulata faunule. c> This faunule 

contains Ambocc&lia 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; d and above 

that came the Spirifer lazvis 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 Icuvis

«On the fossil faunas of the Upper Devonian along the meridian of 76° 30' from Toinpkins 

County, N. Y., to Bradford County; Pa., by H. S. Williams: Bull. U. S. Geol. Survey No. 3.

&The 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-XHI.

cBull. U. S. Geol. Survey No. 3, p. 9.

d Ibid., p. 11.

«Ibid., p. 12.
70 CORBELATION OF GEOLOGICAL FAUJ5TAS. [BUM,. 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 Ambocmlia belongs to the dominant Tropidoleplus 

faunal list.

Above all these appears the typical Ithaca fauna, which now may 

be called the Productella speciosa fauna, from the species of Productella 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 Avas, at the time of writing the report, regarded as 

an early form of the species so named, then regarded as a Chemnng 

species. This common Ithaca-form is now called Spirifer pennatus 

var. posierus. (l

In the report e 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 arenaceous 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 G-enesee shale conditions, 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 variational 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 (mucronatus) pennatus of the eastern counties to Spirifer pennatus var. posterus? 

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.

fclbid., p. 15.

dbid., p. 17.

^Palaeontology New York, Vol. VIII, Part II, p. 36fpl. 34,18&5.

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

/Palaeontology New York, Vol. VIII, Part II, p. 361, figs. 27-31, PI. XXXIV.
WILLIAMS.] 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 distinguished from, lower or higher strata, nor does it contain in its fauna 

any characteristic species of the Ithaca expression of the lower Portage formation. Nevertheless, the identification of the strata as the 

ontcroppings 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 

co'lor to the region from which the 15 reported faunules came is 

defensible, if: it be granted that the same formation name may be l ? '/ 

applied to strata of which the contemporaneous sedimentation can be > , .

' ' > -l / .

established, although their lithological andpaleontologicalcharacters'")','/./ 

are different. , > A WJ' ll / ^*

I take this case from the region holding the typical Hamilton formation, 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 byProsser, 41 species are 

positively identified.

Of these 41 species, 34 are recurrent species, and among the dominant species of the Portage fauna occur five species and two varieties of the Tropidoleptus fauna.

Of the standard Tropidoleptus carinatus list, six species are reported 

the number of times, out of a possible 15 local!ties, indicated by the

figures in the following list: nJ* /

* C> W/I/HVX'MTABLE X. Recurrent species* of the Tropidoleptus fauna in the Portage formation.

Tropidoleptus carinatus. .-----.-...-.._._.._._.____.__...._____ .__.___._...___ 8

Nucula corbulif ormis ......................................................... 3

Palteoneilo constricta.............I..........__,.._._._.___...._._._._.._.__. 3

Nuculites oblongatus ........................................................ 3

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 .................... ..I.... ........ ........'. ......... 4

6. Prothyris lanceolata ............ .................... - ...................... 2

7. Palseoneilo filosa ...-..-......."...._....---........-......... .-..-.-....:....-. 1

Putting these two lists together, it will be seen that the characteristic 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 formation, 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 eastern counties at 15 localities, with 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 hoydi ....................................................... 8

5. Spirifer mesistrialis . ........................... ............................ 7

6. Palseoneilo 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 o^ that region, viz, the Tropidoleptus fauna, so 

that the former might be called the Posterus subfauna of the Tropidoleptus 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.] FAUKAL DISSECTION OP 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 farinas directly following the Genesee shale in the Ithaca region, were fully analyzed into distinct subfaunas, and in later papers the extension of these subfannas to their 

prevalent common faunas to the east and Avest was traced. The 

recurrence of Hamilton species was also there distinctly'recognized in a small fannule occurring in the lower part of the Cascadilla 

Creek gorge (station No. 14 N.). The University quarry (station 5) 

and the "inclined plane" section on South Hill arid 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 University) made an exhaustive 

study of the Ithaca fauna, and to illustrate this particular fauna pnt 

together in a Aralnable memoir all the statistics then in hand. This 

was published in 1.896, b 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, situated in the town of Ithaca and in the immediate neighborhood, furnish 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 are 

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 contain but two oi' three. They are the chief fossiliferous outcrops of the 

region, presented by ravines, quarries, and occasional outcrops on the 

steep hillsides about Ithaca. They do not, however, present as comoBull. U. S. G-eol. 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. G, Dec. 25,1806. Ithaca.
74 COBEELATION 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 frequencj^ of occurrence of the species in the 54 faunules analyzed: "

TABLE XIII. Productella speciosa fauna: Dominant species of the Ithaca 

formation at Ithaca, N. Y.

1. Spirifer pennatus var. posterns .------._._.._...._.._'._..__________..._.__ 35

2. Productella speciosa.. .................................................... 2ri

3. Modiomorpha subalata vai'.. chemtmgensis ---._----.----.-_.-_-.......... 25

4. Chonetes scitulus ....................................................... 24-.

5. Cyrtina hamiltonensis- ..............................................^.... 23

6. Palaeoneilo filosa ----.....-...-...-.-.-.-...-. ..............'............ 21

7. Camarotoechia eximia and stephani....___'____ ____.___.__ .______._.____. 21

8. Atrypa reticnlaris -..........,-----.-.---..-.-..------.-.-----.------.--- 20

9. Stropheodonta mticronata ...,.-.-.-.-..-.--......-.--...........j........ 19

10. Actinopteria boydi..............'. ..-,.-....-.-...--..-.........-...--... 19

11. Pleurotomaria capillaria ................................................ 19

12. Stictopora meeki .......i.......................^............... '........ 17

13. Palgeoneilo constricta ....'.... .......--..-..-.-...-.-- ..---.-.-..-.-.----. 17

14. Cypricardella bellistriata.....-...---.....-. ............................. 15

15. Spirifer mesistrialis. .............-.---.-.- ....-....----..........-...-... 14

16. Leiorhynchus mesicostale -..-...----....._.........-.-.................... 14

17. Grammysiasubarcuata --.....--..'-.-........--.--.-.--'......-..--....--. 14

18. Orthoceras bebryx var. cayuga .-.----....--...-.-...--.-..-.....-.-....-. 14

19. Amboccelia umbonata. _...................-...-...................-..... 13

This maybe considered as a standard list of the fauna of the Ithaca 

formation. Three points must be noted, however: (1) Several characteristic 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 species (i. e., species of the standard Tropidoleptus carinatus fauna); 

(3) the species which are peculiar and dominant are closely related 

to species of the Tropidoleptus carinatus fauna. It Avill be noticed, 

however, that not a single one of the dominant species of the Tropidoleptus carinatus f auna 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., Palczoneilo constricta and Ambocqdia unibonata. .
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)7 the effects of shifting its habitation. The distributional values of the species will be furnished by the statistics of the 

eastern faunules.

Analysis of the statistics gathered by Professor Prosser in the eastern counties of New York" 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 differences in original environmental conditions. The localities from 

which the faunas of the Ithaca formation are reported by 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-quarters, 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 67 localities, the second, collections from 14 localities.

TABLE XIV. Productella speciosa fauna: Twelve dominant species of the Tropidoleptus fauna found also in the Ithaca formation of the eastern counties of 

Neio York. , . ^tW^M^~

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

*2. Tropidoleptus carinatus ...-............-.-.-.-...---.-'....-..

3. Nuctila bellistriata. ...-......-...-.-....--....-.-..---.....-.-

*4. Palseoneilo constricta --..-..........---.....-.--....-...-....

*5. Nuculites oblongatus .-.-....-.-...-..-...-.......------.--.--

*6. Phacops rana . . .......................... ....................

*7. Nucula corbuliformis ..........................................

8. Ambocoelia timbonata. - ........................................

9. Athyris spiriferoid.es ................... ......^......... ......

12. Chonetes coronatus. -..-........'.....-..-....-.....--..'........

31

31

7

7

6

6

6

2

2

2

2

2

13

13

4

4

5

5

4

3

2

2

2

1

« Classification and distribution of the Hamilton and Cheinung series of central and eastern 

New York, Part 1, by C. S. Prosser: Fifteenth Ann. Kept. State Geologist New York, 1895, pp. 

87-225.

Idem, Part 2: Seventeenth Ann. Kept. State Geologist New York, 1900, pp. 07-327.
COKRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

The first 2 species of Table XIV are still dominant in the fauntile 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 bj* examination of the list of 

species having highest distributional and abundance values in the 

Ithaca faunules. Table XV, representing collections from 67 localities,, shows the dominant species of the eastern extension of the Ithaca 

formation. Comparison of Tables XIV and XV will show how completely 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 extension of the Ithaca formation.

1. Spirifer mesistrialis ..........-..---...-:-..-....-...-..........'-

2. S. permatus - -------.._-._--- ........................ _..__-...._'.

4. Camarotoechia eximia .._...__-_-.._.__-_...-__.._ 1 ..............

5. Chonetes setigems ..............................................

7. Chonetes scitulus. . ...--.-..-.--.--..---..-..-.....-.-....-.....-

10. Camarotoechia -stephani -.---... ...-.-... ..-....--.:..---...-..-.

12. Cypricardella gregaria ..-...-,.-.-..--...-..-...................

3fi

81

81

19

9,0

18

15

19,

19

9

19

9

fi

4

0

ft

0

0

0

9,

1

8

0

1

94

19

10

19,

9

4

9

7

7

7

0

4

In the first column of Table XV is given the number of positively 

identified occurrences in 67 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 the 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 pennatus'm&y be confused with S. pennatus var. posterns, 

of which 1 doubtful case is recorded, and with S. 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.

PKODUCTELLA SPECIOSA FAUNA.

In 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 Produciella 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 Tropidolepius fauna, but are there rare, are A.ctinopteria boydi 

and Paracyclas lirata. These, though frequent in the faunules occurring east of. Fulton, Schoharie County, are rare in the Hamilton formation west of that point. Cypricardella gregaria, though occasional, is very rare in the eastern Hamilton faunules. Another 

species of the genus, C. lellistriata, is common in the Hamilton formation.

It is evident, therefore, upon purely paleontological grounds, that 

tliis 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 th'e fact that it contains all of the 12 dominant 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 Tropidolepius fauna.

The correctness of this interpretation is further supported by the 

presence of species entirely wanting in the underlying Hamilton formation of the region, but present in the Ithaca formation, at its typical expression in Tompkins County.

Table X\TI is compiled from the statistics reported by Prosser in 

the papers already referred to:

TABLE XVI. Procluctella speciosa fauna: Tiventy-one species characteristic of 

tJte Ithaca formation of eastern New York and Pennsylvania not occurring in 

the Tropidoleptus fauna.

[The starred speuies are dominant at Ithaca.]

* 1. Camarotoechia stephaiii.

* 2. C. exirnia,.

3. Cryptonella eudora.

* 4. Leiorhynclras mesicostale.

5. Orbiculoidea media.

6. O. neglecta.

* 7. Prodtictella speciosa.

* 8. Spirifer mesistrialis.

* 9. S. pennatus var. posterns.

10. Actinopteria perstrialis.

11. A. theta.

12. Grammysia elliptica.

13. G. globosa.

14. G. nodocostata.

15. Leda brevirostris.

16. Luimlicardium ornatus. 

*17. Modiomorpha subalata var. cliermmgensis.

18. Prothyris lanceolata.

19. Pterinopecten stiborbicularis.

20. Sclrizodns ellipticns.

21. Coleolus acicxirum.

Of these 21 species not in the Tropidolept'ns fauna 6 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 (y^r) of the total listed species are of the Tropidoleptus 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 counties. These three species are:

Cryptonella eudora.

Grammysia elliptica.

Actinopteria perstrialis. ' .

IMMIGEANT SPECIES OF ITHACA FORMATION.

Among the species appearing for the first time in the strata of this 

region, distinct affinities with the lowan and related faunas are evident. Examples are:

Productella hallana, 

Pugnax ptignus, and 

Spirifer (Reticularia) laevis. ,

The common Productella speciosa may belong to the same group, 

though it is possible that this is a case of direct evolution from Productella spinulicosta of the Hamilton formation. Rliynchonellavenustula ( = Hypothyris cuboides) of the Tully limestone is a still earlier 

immigrant, as was shown in a paper on the Cuboides zone. a

Ortliis (Scliizoplwrid) tulliensis is another closely related to Orthis 

impressa of the Ithaca zone, and believed to be a variety of'Schizoplioria striatula (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 Carddolas 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 present 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 contains 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 disjuncttis 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. 1,1890, pp. 481-501.

&0n 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.] 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 (see foregoing footnote), and the following species there * listed are also 

reported from the Iowa Devonian.

TABLE XVII. The Pugnax pugmis fauna of HigJt, Point, N&io York.

Camarotoechia contracta var. saxatilis. Schizophoria iowensis.

Pugnax pugnus. Dalmanella infera.

Atrypa reticularis. Orthothetes chemungeiisis.

A. hystrix. Strophonella reversa.

Spirifer orestes. Stropheodonta calvini.

S. litingerfordi. S. variabilis.

S. bimesialis. S. canace.

S. siibattemlatus. S. arcuata.

Prochictella (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 New 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. But 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 Ciiboides fauna to a world-wide 

distribution led to the conception, that affinitievS expressed by faunas 

may be due to migration rather than to direct evolution of the prevalent fauna living in the region. This idea was set forth in the paper 

on. the Cuboides fauna. 6

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 European Devonian faunas, furnished the third clue to the interpretation 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 changes involv-

«On a remarkable fauna at the base of the Chemung group in New York: Am. Jour. Sci., 3d 

series, Vol. XXV, 1883, p. 97.

''The Cuboides zone and its fauna; a discussion of methods of correlation: Bull. Geol.Soc.Am., 

Vol. 1,1890, pp. 481-500.
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 formation 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 Tropidoleptus fauna. The other quarter may be derived by migration 

from a more distant source.

In both cases of origin, however, it will be noted that varietal modifications 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 Hamilton proper up to the departure of the marine species with the sediments of the red Catskill shales and sandstones.

It will be noted also, by examination of the lists already given that 

5 out of the 10 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 dominance of the species in the fauna. If it were far enough removed from 

the Hamilton formation to make correlation by stratigraphical evidence impossible, the faunal characteristics would lead to its association, with the Hamilton, as a stfatigraphically 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 succession 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. Ain. Assoc. Adv. Sci., 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, but 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 Few 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 formation 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 dominance.

(4) Westward from Ithaca the Productella speciosa fauna is traceable 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.

(6) The characteristic species of the Productella speciosci fauna of 

the Ithaca formation as it occurs at Ithaca are present and dominant 

in these eastern counties of the State, although the Tropidolept'us fauna 

still constitutes 75 per cent of the fauna and is represented by all its 

most characteristic species.

(7) If the composition of the fauuules still higher up in the eastern 

coujities .be examined, it will be found that this same Tropidoleptus

Bull. 210 03 6
82 COREELATION 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 Productella 

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 carinatus, and Cypricardella ~bellistriata.

(9) Following the strata westward to the Genesee River section, it 

is found that the Cardiola fauna of the Portage formation has entirely 

replaced the Productella 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 Ice-vis fauna together with the Ithaca formation with its Productella speciosa fauna, and that these latter two 

are equivalent, stratigraphically, 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 Ithaca 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

Chemiing 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 Pennsylvania the Chemung formation is sharply differentiated, strati- ' 

graphically, 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
FAUNAL DISSECTION OF THE DEVONIAN. 83

clisjunctus fauna, and the formation through which this fauna prevails 

is the Cheinung formation.

.SPIRIFEE DISJUNCTUS FAUNA.

The fauna of this typical Cheinung formation, as it appears in the 

southern tier of counties in the western half of New York State, may 

be appropriately called the Spirifer clisjunctus fauna from the brachiopod 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 clisjunctus fauna was applied to it., The original list of species of the faunules examined in the counties directly south of CayugaLake (as then 

identified) included 46 species.

In a preliminary "Catalogue of the fossils of the Cheinung 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 disjunctus fauna, purely on the basis of what I have, in the present 

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 abundance and frequency, statistics which have been insisted on in later 

im^estigations.

TABLE XVIII. Spirifer clisjunctus fauna: .Dominant species of the Chemung 

formation south of Ithaca, N. Y. (roughly estimated in ih,e field).

1. ScMzophoria tioga.

2. S. carinata. 

3. Stropheodonta' mticronata.

4. Prodtictella lachrymosa.

5. Spirifer disjunctus.

6. Atrypa spinosa hystrix.

7. Spirifer mesistrialis.

8. Aniboccelia gregaria.

9. Spirifer (Delthyris) mesicostalis.

10. Orthothetes cliemungensis.

11. Pterinea chemxingensis.

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, 

b See the discussion of bionic values of fossils, p. 124. 

o Bull. U. S. Geol. Survey No'. 3,1884, pp. 22-23.
84 COKRELATION OF GEOLOGICAL FAUNAS. [HULL. 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 characteristic 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. Thirtyseven such Chemung faunules are analyzed. The value of clearly 

distinguishing the geographical from the geological modification 

of the fannules was not fully appreciated when the bulletin was 

written.' As the investigations have progressed, however, it has 

become clear that modification of a general fauna, coincident Avith a 

feAv miles of separation in space, geographically, may be as great as, 

or even greater than, the modification coincident Avith passage upward 

stratigraphically through tens or even hundreds of feet of sediments. 

These two kinds of bionic value (geographical and geological) are not 

so sharply distinguished in Bulletin 41 as they might be, but the statistics 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 aggregation of species making up the faunules, which call for still fuller 

investigation. This plasticity of the fauna is Avhat 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 

aquitory, AATC 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 Arariable that two authors Avill almost certainly disagree in naming the 

species of any particular lot of fossils, and even the ablest paleontologist will differ in his own distribution of the specimens among the

a On the fossil faunas of the Upper Devonian the Genesee section, New York.
FAUNAL DISSECTION OF THE DEVONIAN.

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 Productella recognized as belonging to the Chemung fauna. Spirifers of the three types disjunctus, mesicostalis, and mesisirialis are 

present and eacli type is widely variable. The rhynchonellas of the 

contracta, sa/ppho, 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 footnote to Plate VI, A, of Hall and Clarke's revision of the Brachiopoda, 

contains the following statement about.the orthids:

The species of Orthis=ScMzophoria, described as 0. propinqua, 0. tulliensis, 

0. impressa, 0. ioivensis, and 0. macfarlanii. present so many features in common 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 differences 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 common 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 it 

occurs in the Genesee Valley section.

Species.

var -....-...----.-.....--..

4. Orthothetes chemungensis

 G. Schizophoria striatula irnpressa

Thirtyseven localities.

24

16

12

10

9

7

Species.

vars .............. ......

8. Ainboccalia tunbonata ......

10. Chonetes scitulus ...........

Thirtyseven localities.

21

7

7

7

6

4

A list of the species of the Chemung formation of Chautauqua 

County (prepared by G. D. Harris in 1887), 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.

species in each faunnle, shows the following species to be dominant 

in approximately the order in which thej^ are listed below:

TABLE XX. Spirifer disjunctus fauna: Dominant species of the Chautauqua

County faunules.

1. Camarotoechia contracta.

2. Spirifer disjunctus.

3. Ambocoelia 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 characteristic species brings out some peculiarities in geographical distribution which should be here indicated; Orthids of the Schizophoria 

type, like impressa and tioga, are more conspicuous in the eastern 

than in the western faunules of the State, and in range they are conspicuous in the lower rather than in the higher portions of the sections. 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. Camarotozchia 

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 common species, there is a much larger number of species which are dominant 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 standard 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 XXI. 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. Camarotcecliia contracta. 12. Orthis (Schizophoria) 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. Grramrnysia communis.

7. Spirifer mesistrialis. 17. Chonetes scitulus.

8. Orthis (Schizophoria) tioga. 18. Camarotcechia 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 

disjundus fauna from statistics already gathered is that of analyzing 

a set of faunal lists, all of which contain Spirifer disjundus. 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 disjundus. 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 each species is reported in the 16 faunules.

TABLE XXII. The Spirifer disjunctus fauna, with its more dominant associates, 

as represented in the Genesee section.

1. Spirifer disjunctus...---.--.-.-- 16.

2. Camarotoechia contracta ...._._- 13

3. Orthothetes chenrangensis...---. 8

4. Athyris angelica ______.-___....- 8

5. Chonetes scitulus .....__.-_.-_-_ 7

6. Productella hirsuta -.........'..'. 7

7. My tilarcachemungensis _.._-.._ 6

8. Sphenotus contractus........... 5

9. Orthis (Dalmanella) leonensis .. 4

10. Orthis (Schizophoria) impressa. 4

11. Ambocoelia uinbonata .......... 4

12. Productella costattila .......... 4

The first 7 species of this list are among the standard forms determined 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 conspicuously in faunules actually containing Spirifer disjundus, 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 

disjundus occurs, viz: Elmira, Leon, Painted Post, Factoryville, 

Cayuta Creek, Chemung Narrows, Conewango, Great Valley, Randolph, Napoli, New Albion, Chemung, Bath, Angelica, Troupsburg, 

Mead ville, Pa., Twentymile Creek, Ellington, Olean, Covington, Pa.

From these localities the following species are recorded for the number of localities indicated:

TABLE XXIIa. Species listed from same localities loith Spirifer disjunctus in

Neiv York reports. 

Camarotcechia conl/racta............---.--.-.---..--.-.--....-.-....---..--. 10

Orthothetes chemungensis. .......-..-----...---.---- .-.---..--.-.- ....-.-... 3

Athyris angelica -.....-........... ....--.....-.---.--.-.......-......-.-.... 3

Productella hirsuta and var ........-...-...---.--....... .................... 17

Sphenotus contracfrus .-....-.......-----.....-.--.-.. -...-....-........---. 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 conspicuous species were gathered, or perhaps the fine specimens only

"Palaeontology New York, Vol. IV, 1807.
88 CORRELATION 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.

Camarotoechia 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 mesistrialis is common in the lower Ithaca zone; and in the zone dominated 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 faunule.

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 (Camaroto&chia) show a definite succession of 

species. The Ithaca zone carries C. eximia and stephani, and occasionally forms identified as C. contracta; but typical C. contracta, with 

the small number of plications, is confined to the higher horizon, and 

runs into the forms called C. orbicular is'and C. sappho or C. alleghenia in the typical higher Chemung. E. (Pugnax) pugnus 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 faunules 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 localitjr holding a typi-
WILLIAMS.] FAUNAL DISSECTION Otf THE DEVONIAN.

cal Chemnng 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 regarding the actual distinguishing features of the fauna of the typical Chemung 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 disjimctus and as to the exact 

strati graphical horizon from which the species came..

The present paper can therefore .go no further in precision of definition 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 Chemung rocks, who will render a service to science by furnishing accurate lists of the species, with statistics as to the exact locality and 

zone and the relative abundance of the species in each fannule.

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 U. S. Geological 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 lime 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 at 

least 50 feet "of the typical horizon of the Chemung formation iii Chemung 

County, and also in the midst of the Chemung, or Spirifer dixjunctus, 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 faiina are such as 

Tropidoleptus carinatus (abundant). 

Ambocoelia umbonata (abundant). 

Phacops rana (rare, but with several specimens).

"Bull. U. S. Geol. Survey No. 8,1884, p. 24.; also Proc. Am. Assoc. Adv. Sci., Vol. XXXIV, 1886, p. 

22(1. This is the stage A°+ of the Tropidoleptus fauna, called in that paper Middle Devonian 

fauna A; also p. 230.
90 COKRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

It also contains such characteristic species as 

Spirifer marcyi, and probably S. granulosus.

Cypricardella bellistriata..

G-oniophora hamiltonensis.

Macrodon hamiltoniee.

Loxonema delphicola.

Modiomorpha naytiloides.

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 County, on side hill above and southeast of the old Erie station, collected 

by H. S. Williams (U. S. Geological Survey station 1130 A).

1. Spirifer marcyi var. aa .« Hamilton.

2. Ambocoelia umbonata aa 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 hamiltoniae rr Hamilton.

17. Lingula sp. rr

18. Pterinea sp. rr

19. Grammysia sp. rr

20. Palaeoneilo 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.

a a, abundant; aa, very abundant; c, common; r, rare; rr, very rare.
WILLIAMS.] FAtJNAL DISSECTION OF THE DEVONIAN. 91

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

follows:

TABLE XXIV. 'Tropidoleptus faimule as a colony in Chemung formation, Waverly, 

N. Y. (146S B,U.S. Geological Survey), identified by E. M. Kindle (1902).

1. Tropidoleptus carinatus a "Hamilton.

2. Ambocoelia umbonata a Marcelltis-Chemnmg.

3. Rhipidomella vanuxemi c Corniferous [Onondaga]-Hamilton.

4. Spirifer marcyi c Hamilton.

5. Cypricardella bellistriata c Hamilton.

6. Productella lachrymosa c Chemung.

7. Delthyris mesicostalis c Ithaca-Chemnng.

8. Camarotoechia contracta r Portage-Waverly.

9. Schizophoria cf. tioga rr Portage-Chemung.

10. Leptodesnia matheri rr Chemung.

11. Glyptodesma erectum rr Hamilton.

12. Pterinopecten sp. rr

13. P. crenicostatns rr Chemung.

14. Modiomorpha cf. concentrica rr Hamilton.

15. Cyrtina harniltonensis rr Up. Held., Ham., Portage, Chemung.

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 freqxiency 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.'' There are no species 

. there which might not occur as low as the Ithaca group. But the faunule collected 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 1'ropidoleptus 

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 eqtiilibrium had not been disturbed, and therefore that the life history of the fauna of the Hamilton forma-

«o, abundant', c, common; ? , rare; rr, very rare.

& Since the above was wi'itten I have examined the Owego locality and another locality west 

of Waverly, and have proved beyond controversy that this recurrent Hamilton fauna occurs not 

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 Hall's Report 

of 1843. (Part IV, Geology New York State, p. i252.).-H. S. W.
&2 CORItELATtOtf .OF GEOLOGICAL FAUJSTA&. [BULL. 210.

tion had not ceased, while the faunas above and below in the cliffs in Chemting 

Narrows is evidence that the geological horizon is that of the typical Cheniung 

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 faxina is not what it appears to be in any particular 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 evidence should be interpreted as positive that the boundary between the two consecutive 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, interpreted 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 boundary 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 dominant species of the Spirifer disjunctus 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 may be noted that 

among the 20 dominant species listed in Table XXI (the Spirifer 

disjunctus fauna), three are reported by Grabau from the Hamilton 

formation of Eighteemnile Creek. These are Amboccdia umbonata,

Chonetes scitulus, and Pcdaoneifo consirida. The same species, and 

the variety arctistriaius of Orthotlietes cliemungensis 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., Ambocmlia 

umbonata, Orthotheteschemung en-sis, 'Chonetes sc/iiulus, and Palceoneilo 

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 Chemung 

formation.

In the sections in Chenango and Otsego counties above the Oneonta 

sandstone occasionally a few species occur which have led to classifying 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. XT.TJ, 1.902, pp. 428-4S1.
WJLLIAMS.] 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 concerned makes it clear that the classification is more strongly influenced by the lithological than the paleontological evidence." 

- Regarding this point Prosser ^ says:

After reviewing the results obtained by different investigators of this problem 

of the separation 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 impressa 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 Township, Oneicla County, tip into the Chemung, on top of the hill in Fenton and Kirkwood townships, Broome County, to the northeast of Binghainton. is approximately 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 perhaps 25 feet, representing the Ttilly 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. 

Chemung ......._'_'_.... T ...... 1,225

Oneonta ...... ........... 1.... 550

Ithaca.....,,____._.._._._.___ 500-

Foct. 

Sherburne ................... 250

Genesee and Ttilly ........... 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,"c the necessity for using some other 

term for the name of a fauna than the geographical name of a formation becomes apparent, for the fauna in Greene County referred to 

does not represent the Spirifer disjunctus fauna, which is characteristic of the Chemung formation in its typical geographical area. Statistics 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.

« See Report of field work in Cheuango County, by J. M. Clarke: Thirteenth Ann. Rept. New 

York State Geologist, 1898. Vol. I.

''The classification and distribution of the Hamilton and Chernuiig series of central and eastern New York, Part I, by C. S. Prosser: Fifteenth Ann. Rept. New York State Geologist, pp. 1.65-166. - 

o Clarke, loc. cit., p. 557.

rf Classification and distribution of the Hamilton-and Chemung series of central and eastern 

New York, Part II, by Charles S. Prosse'r: Fifteenth Ann. Rept. New York State Geologist, 1895, 

pp. 87-222. Classification and distribution of the Hamilton and Chemung series of central and 

eastern New York, Part II, by Charles S. Prosser: Seventeenth Ann. Rept. New -York State 

Geologist, 1899, pp. 07-327.
94 . CORRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

There are 29 faun ales occurring1 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: Cliar.acteristic representatives of the 

fauna reported in the eastern counties of New York and Pennsylvania.

1. Spirifer mesistrialis ............. 6

2. Productella lachrymosa .........' 8

4. CamarotcBchia contracta ........ 1

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, Chenango County. b

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. c

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

Fossils are abundant throughout these shales and are of typical Chemung 

expression.^ .

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. 6

The one record of Camarotazchia 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 section southwest of Port Crane near the top of the hill. This observation 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 corporate fauna as a whole.

We have the carefully 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,

"Three times positively.

6 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. 27-81.

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

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

c Table XXV, above.

/Fifteenth Ann. Rept. State Geologist New York, p. 160. ; '
WILLIAMS;] FAUNAL DISSECTION OF THE DEVONIAN. 95

there are 23 more named with a query, and 31 entries in which only 

generic or more general identification was made. Of this total of 65 

species 27 species are also listed in the fan miles of the Hamilton 

formation; they are given in Table XXVI.

TABLE' XXVI. Species of the Tropidoleptus carinatus fauna occurring above 

the Oneonta sandstone in eastern New York.

1. Ambocoelia umbonata.

2. Atrypa reticularis.

3. Camarotoechia congregata.

4. Chonetes scituluS.

5. C. setigertis.

6. Coleolus tenuicinctuin.

7. Cyrtina hamiltonensis.

8. Granimysia bistilcata.

9. G. circnlaris.

10. G. subarcuata.

11. Leda diversa.

12. Leiopteria bigsbyi.

13. Loxonema xlelphicola.

15. Ltinulicardium fragile.

16. Cypricardella bellistriata.

17. C. coraplanata.

18. C. gregaria.

19. Niaculites cuneifomiis.

20. N. oblongatus.

21. Orthis (Schizophoria) impressa.

22. 0. undulata.

23. Palaeoneilo plana.

24. P. constricta.

25. Spirifer granulosus.

26. Stropheodonta demissa.

27. Tropidoleptus carinatus.

14. L. hamiltoniag.

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 formation. The 5 not listed by Prosser in the Ithaca are 

Stropheodonta demissa. 

Orthis (Schizophoria) impressa.

Grarnmysia circtilaris. 

Loxonema delphicola. 

L. hamiltonise.

Both Stropheodonta demissa 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 are also in the Ithaca, but not 

in the Hamilton formation.

1. Camarotoechia stephani.

2. Cyclonema multilara.

3. Grammysia elliptica.

4. G. nodocostata.

5. Leiorhynchus mesicostale.

6. Delthyris mesicostalis.

7. Spirifer mesistrialis.

8. S. pennatus posterus.

Palczoneilo 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 mesistrialis and 

Delthyris mesicostalis are among the characteristic and dominant 

species of the standard Spirifer disjunctus fauna (see Table XXI), So 

far as their evidence bears upon the case, their appearance in the
96 COBRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

Ithaca formation, which has been demonstrated to lie below the Chemung in the Ithaca section/' is opposed to the supposition that the 

horizon now under investigation is as high as the typical Chenmng 

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. Bellerophcm msera........... 2 3

2. Camarotoechia contracta.

3. Edmondia philipi.

4. Ectenodesma birostratum.

* 5. Goniophora subrecta ........ 2

6. G-rammysia coinrtranis.

7. Holonema rugosa. 

S.. Leiopteria rafmesquii.

* 9. Leiorhynchus globuliforme . -' 9 1

*10. Leptodesma sociale .......... 4: 3

*11. Lyriopecten priamus .......... 3

*12. L. tricostatns ...... r ........... 4 2

*13. Modioniorpha qtiadrula.__--- 4

15. Onychodus hopkinsi.

16. Palseoneilo brevis var. quadrangularis.

*17. P. brevis.....--..----.-----. 3. 3 

18. Pleurotomaria itys.

*19. Productella lachryniosa _ - - - ^ _ 8

*20. Pugnax pugnus------------- 3

21. Schizodus gregarius.

22. S. chemungensis.

*23. S. chemungensis var. quadrangularis ........-.---..- 3

24. Sphenotus contractus.

25. Spirifer disjunctus.

14. Mytilarca carinata.

The species starred are mentioned in more than one faunule; 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 lachrymosa. 

Camarotcechia 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 Spirifer disjunctus fauna. 

TABLE XXIX. Dominant species above the Oneonta not confined to the horizon

of the Chemung formation in western Netv York. 

Spirifer pennatus posterus. Delthyris mesicostalis. 

S. mesistrialis. , Pugnax pugnus. 

Camarotoechia stephani. Chonetes. setigertis. 

Cypricardella gregaria. Camarotoechia exiniia. 

Tropidoleptxis carinatus. Palseoneilo 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.

In 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 Catski.ll, in 

the eastern counties of Few 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 Produdella 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 Cheinung 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 representatives of typical species of the Tropidoleptus carinatus 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 Chemuug; 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 stratigraphical 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 97
98 COKKELATION 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 gibbons form of Leiorhynchus, tinder the name Atrypa globuli- "? 

formis, was noted by Vanuxem as existing in myriads in the "Chemnng group" of the third district, "numerous localities abounding 

with it." 6

The close relationship between the species so abundant in the arenaceous strata overlying the Oneonta sandstones of Chenango and 

Otsego counties and the common flattened form Leiorhynchus mesi- * 

costale was recognized by Hall. 6'

The presence of the species in the Ithaca formation was noted in ^ 

ISSi/* 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. globuliforme 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 retlcularis, although the variations of form and the relative prevalence 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 following the Oneonta sandstone in the Chenango Valley, and that this 

species should appear there in place of Leiorhynchus mesicostale 

was looked upon not as indicative of a new species, but as evidence 

of changed conditions of -environment modifying varietally the common 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 Leiorhynchus globuliforme was among the earlier species to appear 

above the sands and flags (nearly barren of marine invertebrates) - 

above the horizon of the Oneonta sandstone. The fact that the sper cies appeared in the Ithaca formation associated with the characteristic 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 .ylobulifor me fauna was a representative 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. 

bGeology of Third District of New York, p. 182.. 

cPaleontology New York, Vol. IV, p. 364, 

l. 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 Geuesee 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 take a wedge-shaped

position in the sediments rather than make a continuous superposition 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 evolution in Chenango County than in Tompkins County.

Taking this view of the case the Oneonta formation is, stratigraphically, 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 stratigraphical equivalent of the barren 300 or 400 feet of the Ithaca section and the fossiliferous beds of Caroline, which lie between the 

fossiliferous Ithaca formation with the Produciella speciosa fauna 

and the Cheinimg formation with the Spirifer disjunctus fauna.

The geographical shifting of faunas coincidently with the accumulation of sediments not only is consistent with all the 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 the sandstones and flags in the midst of the Ithaca formation, and the Oneonta, 

by its becoming thicker and more strongly marked on passing eastward in Chenango and Otsego counties, is seen to have its origin from 

that direction.

The black shales of the Genesee and the following fine mud shales 

of the Portage of western New York containing the Cardiola fauna 

( Gflyptocardia 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 CORRELATION 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 

coi'rect, if by the '' typical exhibition " be meant a case in which the separation 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, Chenaugo County, there is an undisputed mingling of a large number of species of the standard Tropidoleptus 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 formation.

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 column 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 adjacent counties in the eastern part of the State, but by the fossiliferous 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 sandstone is the formational equivalent of the "Portage sandstone,"" 

this does not dispose of the essential problem; because the equivalency 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 western 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. b

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. Kept. State Geologist New York, 1893. p. 557. !>See p. 117.
WILLIAMS.] SHIFTING OF FAUNAS. 101

but so far as such work has already been carried the evidence is all 

against the supposition that the sandstone of the Otsego section 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 

fti&ilithological 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 lithological constitution must be regarded, in some cases at least, as positive evidence of nonequivalency 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 corporate fauna of each epoch of time for the area covered.

The presence of a few species which are common in the typical 

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:defmed 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 Ic&vis 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 considerable 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 formation. In such range of a fauna through hundreds of feet of
102 COKRELATION 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 any 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 geographical^, for 

much distance of distribution; such a faunule with its exact combination 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 the 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 equilibrium, and the effect of the change is exhibited primarily in the different relations of abundance or rarity of the constituent species.

The difference in these respects observed upon comparing the successive 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 .facts 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 succession of faunules as recorded in the geological column of a single section, and coincident with changes of conditions as indicated by the 

faunules taken from separate geographical localities.

The species which appear most frequently in sample faunules, representing 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 dominant species of a fauna may be safely regarded as indicative of the 

epoch in which the fauna was dominant, and which may be appropriately 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
WILLIAMS.] SHIFTING OF FAUNAS. 103

proved their dominance in the fauna are not replaced by other 

species.

Upon reading on this basis the time value of the Leiorhynclius 

globuliforme faunule of Cheuango Count}7 , 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 Spirif&r 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 shiftings 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 evidence 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 statement that the Ithaca group fauna is a modified Hamilton, fauna, with 

the following: "It contains a more abundant representation of unmodified 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 " unmodified " 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, the Ithaca and 

the Portage groups in central New York: Fifteenth Ann. Rept. State Geologist New York, 

1807, pp. 31-81. .

''Ibid.; see p. 53, etc., for the lists, and fig. 5, p. 5.1, for the diagram.
104 COREELATION 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 shifting 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, to the Ithaca formation of the Cayuga Lake section, 

and to the Portage formation of the Genesee River section.

From the established fact that the Catskill (a formation discriminated 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 differentiating 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 nomenclature 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 preserve 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 may come in during the course of this 

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 conditions have changed and the fauna is broken up. It is not 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 stratigraphical section. Throughout the geological 

column many cases are known where one fauna is immediately followed by another, without greater break of sedimentation than the 

passage between two strata and with perfect parallelism of the contiguous 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 from 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 shifting of 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 contemporaneously 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 appearance 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 jTears; 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 illustrated 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 geologically very slow in its effects; that so long as the same conditions prevail with sufficient exactness to prevent the disturbance of the biological equilibrium of a fauna, so long the individual species will retain 

their distinctive characters and relative abundance in a general fauna.

"Am. Jour. Sci., 3d series, Vol. XXIV, p. 366.
YULLTAMB,] SHIFTING OF FAUNAS. 107

On the other hand, it is assumed that changes of conditions of environment, which may have been very slight but which necessitate a shifting or migration of the faunas, may produce some and even considerable 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 shift 

some species will be forced to drop out, because they can not migrate or 

because they can not adjust themselves to the.new conditions. If 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 different; 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 frequently observed that variability also is increased.

Relatively speaking, the variability is almost in proportion to the 

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 the modification 

of some of the species almost immediately, and the variability of the 

fauna will be strongly expressed when migration of the species takes 

place. The adjustment of the fauna to its changed conditions is a 

matter of slower accomplishment, but it may be supposed that migration from one. region to another will result in more or less modification 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 without disturbance of its bionic equilibrium. Such cases would be rare 

and the distances not great.

The investigations of Grabau and Cleland, already referred to, illustrate this principle. The study of the Cayuga Lake section was made 

for the purpose of furnishing a minute comparison with the Eighteenmile Creek section, as well as to determine the exact composition of 

the temporary combination of species found in each stratum. The 

result was very clear. The general fauna was found to be very much 

alike from the bottom of the Hamilton up to its top in both sections. 

The difference between the several zones was constantly fluctuating,
108 COERELAT10N 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 abundance 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 differences 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, according to the above interpretation, it is observed that the faunas occupying 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 GEOLOGICAL FORMATIONS.

I

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 fauna! equivalency for the different parts of the region 

examined. In other words, if we attempt to trace a common geological horizon across the country by means of the evidence of formational 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 sedimentation 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 Oneoiita sandstone and its place in the midst of the 

faunas, described in detail on previous pages of this report, is another
SHIFTING OF FAUNAS. . 109

vivid illustration of the fact. As a formation the Oneonta is a welldefined body of rock in Otsego County, New York, occupying a definite 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 Cheinung above. The rocks here are known as 

the Portage formation. Following the rocks occupying the same geological horizon still eastward, by the time we reach the meridian of

Oayuga 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 Cheinung 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 quarries 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 holding 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, (5) the relatively 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 finegrained somewhat arenaceous sediments which have the peculiarity
110 COEEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

of being made up of very thin and even larninse 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 irregularly among the sediments. These peculiarities indicate quiet conditions of sedimentation conditions not enough disturbed by currents 

or even wave action to affect the smoothness of the sediments on the 

bottomland show that the sources of the sediments were at a considerable 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 and sandstones, with occasional indications of shore action in 

the form of ripple marks, worm tracks, and pebbles.1 " 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 Geuesee 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. The}' 

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 laud 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 themselves, 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 /one of littoral sediments, rich in organic marine life.

Going still farther outward from the shore Hue the more or less barren 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 stops in the sections of western New York with the deposit of the Genesee shale, 

.while in eastern New York the dominant species of the fauna continue on for several hundred feet of strata .above the horizon of the 

Genesee shale, the inference is justified that not only has the Tropidoleptus 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 sedimentation corresponding to the Portage phase of sedimentation.
112 CORKELATION OF GEOLOGICAL FAUNAS. [MULL. 210.

This phase may be recognized in the Sherburne formation of Chenango County." 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 eastern part of New York is at the same horizon as the fossiliferous 

Cheniung 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 chronological relations of the formations which hold the fossils may be determined 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 sediments occur was sinking, and the shore line was becoming more distant; 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 sediments and their distribution and succession furnish a means of .correlation 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

"See section at "Nigger Hollgw," 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" I adopted, 

as a working hypothesis, the view that limestone sedimentation constitutes 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 at 

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 shifting of the faunas.

This particular order of distribution of the conditions of sedimentation in relation to distance from shore line may require modification 

as the facts are more thoroughly elaborated, but that the several contemporaneous faunas associated with distinct types of sedimentation 

have shifted together laterally seems to be established beyond question. 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 theoretically an established fact.

(2) Sediments of each class are'of limited geographical distribution. 

This fact taken with No. 1 makes the following a rational conclusion, vi/:

(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 established facts, as shown on the 

previoiis pages of this discussion..

(5) A formation (when understood to be a continuous series of

"Bull. Geol. Soc:. Am., Vol. I, 1.890, p. 48L.

Bull. 210 03 8
114 CORRELATION OF GEOLOGICAL KAUNAS. [BULL. 210.

superimposed strata, composed of the same class oflithological 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 lop 

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) frequent difference inrelative abundance of the species of the faunules of a continuous fauna is established 

by the statistics already given.

By the hypothesis proposed the shiftings 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 sediments 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 immediately eastward in the following way:

The Hamilton formation is found underlying the whole State, reaching from eastern New York across the State and into Ontario, Canada. 

It contains a rich marine fauna, and for that reason is clearly traceable 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 southwestward, 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 Tropidoleptus carinatus fauna. Taking the presence of this fauna as the basis
WILLIAMS.] SHIFTING OF FAUJSTAS. 115

of discrimination of the Hamilton formation, the latter in central 

New York is followed directly by the Tally 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 particular series of marine faunas is that of the Onpndaga.

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 Geuesee 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 its continuance on until the very base of the Oneonta sandstone. This is evidence 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 shoving 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 

by 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 Leiorhynchus globuliforme zone, which follows in the stratigraphical succession above the horizon at which the Oneonta sandstones 

cease in the Chenango Valley. Here is indicated a shifting backward 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 it 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 occupation 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 counties of Pennsylvania and adjoining borders of New York we find them 

represented and mixed with the typical Spirifer 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 Pennsylvania. But during the Catskill occupation of eastern New York and 

Pennsylvania, the Spirifer disjunctus fauna prevailed over most of 

the western half of these States, in a thousand or- more feet of sediments, from which the red sediments of the Catskill are almost 

entirely, and for the more western sections entirely, absent.

With 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 their 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 modified, chiefly, at the periods when the shifting took place. The shifting 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 iu the New York province 

during Devonian time, we are led to believe that along with the oscillation 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 favorable 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.

EQTJIVALEJSTCY AS INTERPRETED BY GEOLOGISTS. 

DIVERSITY OF INTERPRETATION.

There is no problem in geology which occasions more controversy 

than that of determining the equivalenc}^ between the rocks or formations of regions separate from one another. In stratigraphical geology

this may be said to be the great problem with which everyone is concerned 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 criticise and modify, in the light of his own newly discovered facts. If I 

mistake not, the chief cause for this disagreement regarding geologfical 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 fanned 

equivalency. But in ordinary discussion it is rarely considered, that 

lithological equivalency, contemporaneity of formation, and faunal. 

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 dealing 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 defiue the 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 2 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 Westville, "New.Haven County,

Conn.

117
118 COEEELATIOISr OF GEOLOGICAL FAUNAS. [BULL. 210.

y

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 denned 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 pre'sent 

configuration of the surface of the earth, chiefly in respect to altitude, 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 geography in order to illustrate more vividly the differences which are confused when a timescale 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 Pocono, 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 Pocono

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 combination 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 composing the rocks were laid down. It is now & faunal time-scale.

3. There is still a third method of defining geological events chronologically. 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
WILLIAMS.] EQUIVALENCY AS INTERPRETED BY GEOLOGISTS. 119

was settled in the case of the Appalachian sheets of the U. S. Geological 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 formation 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 ormauional 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 topis above the boundary line. This 

boundary line is therefore a theoretical one, which does not occur in 

the sti-atigraphical 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 Silurian 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 comparing all the points of geological history for the two separate regions.

1 In the previous pages 'the facts are presented by which the application 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 f ormational 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 greenish shales and flags in the other; this is a case of stratigraphical equivalency. 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 strata, 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 superimposed formations. According to the interpretation here proposed the change would be described as a lithological 

change a change in the character oi: the sediments by increase of the
120 CORRELATION OF GEOLOGICAL FAUNAS. [BUM,. 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 appeal 1 as shales and 

sandstones; and, for instance, the actualstrat[graphical 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 lithologically from what lies below or above it. Such a formation is, strictly 

speaking, but a member, and the reason 1 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 Countj7 , in section 21, east of Noblesville. The 

rocks are described as "smooth, greenish sandstones, in the midst of 

which are blocky shales in which Rliynclionella venustula Hall is 

common ;" rt i. e., a characteristic species of the Tully limestone. Associated with this species are Spirifer (mucronatus) pennatus and Tropidoleptus carinatus, two characteristic species of the Hamilton formation. The rocks below are bluish shales; those above are arenaceous 

shales. The thin '' blocky shales with Rhynclionella venustula (Hypothyris 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 actual stratigraphical equivalent of the formation 

includes more or less of the blue shales below and the arenaceous 

shales above.

An example of the discordance between lithological and stratigraphical equivalency is given by 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 Catskill. In the same way the Chemung formation of the 

Genesee Valley section is stratigraphically 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 formation 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 eastern New York, along a west-east series of outcrops, as shown in PI. I.

"Classification and distribntion of the Hamilton and Cheniung series of central and eastern 

New York: Fifteenth Ann. Rept. State Geologist New York, 1895, Part I, p.183.
U. S. GEOLOGICAL SURVEY BULLETIN NO. 210 PL. I

 Garland 5

Logan-., 

Cuyahopax^ 

Berea,. V "^% 

Bedford";;--^ - 

Cleveland i"""-- :

Huron J .. ',1 

Hamilton'' / 

Delaware J / 

Columbus \

A

IF

^

SlieB.ango- 

__---"Meadville 

_ __ _- " Riceville 

5._---- ~~"~ _ _ ---VeHangb 

_. "Chemung (I.C.W.)

a ~-~-~ -~

Pa

B

 ' '' ' '

11.0

ii:

970

525

475 

i

namar' 

/ 4

(/

3

 _ _ 2

"~---l

c

W

660

950

1315 

-65 

395

 En"

D

_£_

E . -?1

red-hand 4 

3d oil sand

2

1

P*M - '

300 

300

. i" '

R

1500

+

1000

3E

400

Mf. Hermon 

Red beds

- - __ ____ _ 4

Chemung 

3

Portage

Genesee 

Hamilton" -? 

ilarcellus 

Onondaga

"~~~--A

F

1250

^

600

600

450

250 -too- 

-60-

1142 

S

Upper 4

Lo>er

Chemung

Upper 

Portage 

Ithaca 

Lover 

Portage _ 

G«sHe_.2 

Tully

Hamiltoa 

Marcellos

G

?

1525

-rc-**-

550 

500

250

1900 

S

Pottsrille 

Mauch ChunkPoc,oio 

Pocono^Giitskill

/'

s'

Catskill

CatsKill 

4

Chemung 

Chemung

-- ^

Oneonta

Ithaca 

Sherburn Ithaca

~""Seflesee 

(Hamilton. and 7~~~ 

(. Marcellus

Onondaga

%*»H_amilton and ) 

" JUarcellus J

*"^-J

mH /!_

353

300

3600

ISOO

1700

=55=

2100 

ffi

4

^e

2

..1

3000

700 

^5O300 

200

475

1000

1200

too600

1150

1400 

800

FP?

Pot'tsviUe 

Conglomerate

Mauch Chunk

Pocono 

Mt. Pleasant Ss. 

Mt.Pleasantred shale 

Elk. Mountain 

Cherry Ridge

Honesdale 

Montrose

Delaware

New Milford.red shale 

Starucca

Lower 

Portage

Hamilton 

Marcellus

COMPARATIVE CHART OF THE MIDDLE AND UPPER DEVONIAN FORMATIONS OF OHIO, PENNSYLVANIA, AND NEW YORK.
EQUIVALENCY AS INTEBPKETED BY GEOLOGISTS. 121

The sections, A to I, ave arranged in order along a curved line extending from Licking County, Ohio, northeastward toward Jamestown, N. Y.; thence eastward to Ithaca; thence nearly eastward 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 represented is about 500 miles.

The several sections are, for thickness and classification of formations, based upon official survey reports, revised in some cases by 

special surveys; and the range of the fossil faunas has been determined by special detailed investigations, accomplished cMefly by the

persons named below, viz:

A. Licking Coimty, Ohio, revised by Orton, Herrick, and Prosser.

B. Meadville, Crawford County. Pa., and across Erie County, Pa.; Second Pennsylvania 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) 14, 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 Clean, 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; C: S. 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 Eiver, 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 Hamilton 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, it is 

the highest level at which definite traces of the Chemung fauna have 

been detected.

Line 5 is the base of the Olean conglomerate (E) and of other conglomerates regarded by stratigraphers to be its equivalents. In the 

easternmost section (I) it is called Pottsville conglomerate series.

a In section F this line, by mistake, is drawn to cross the section at top instead of at bottom of 

the Tully 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 formation, in its upper measures, contains traces of the Tropidoleptus fauna. 

In western New York the Hamilton formation is composed of argillaceous, 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 represented by Hamilton and Sherburne formations. The Ithaca is in part 

represented by the Oneorita, 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 in western New York and Pennsylvania 

by the upper Chemung, Panama conglomerate, flat-pebble conglomerate, 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 support the opinion are not positively in sight, fossils being out of evidence) that the Pocono and Mauch Chunk are also the representatives 

of this same Waveiiy 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 already 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 distribution, 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 sharply defined in the sections, both lithologically and faunally so there is n6 possible doubt as to the termination of the formation in these western sections we find that the fauna
WILLIAMS.] EQUIVALENCY AS INTEBPEETED BY GEOLOGISTS. 123

which appears in the Ithaca formation contains all of these representative species of the Hamilton formation, thus making a fannal equivalency 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 se.ction in Indiana, the 

inference would be drawn at once that the Hamilton fauna was present. The truth is that the Tropidoleptus 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 

SOine 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 formations 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 compared 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 structural 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 sediments, 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 specifically 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 organisms 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 impossible 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 historical relations of organisms, to find some method of measuring the difference 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 measuring 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 readied 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 they 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 CORRELATION OF GEOLOGICAL FAUNAS. [HULL. 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, tame 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 organism 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 fundamental 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 differencein the forms of organisms is to be accounted 

for by a change in the processes by which the mature body is constructed 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 diversion of the process of development, so as to modify the construction 

and form, is the expression of another unit of force of some proportionate 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 organisms may be compared. Difference in form is the basis of classification 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

taxonoinic 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, expressed by number of individuals of a kind; and number of generations following each other without specific modification) may be elaborated a means of expressing the relative values of living organisms 

in mathematical terms.

These values may be called bionic, 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 associated only with living organisms; and the term b'ion may be used to 

express the idea of such a unit of vital force.

To distinguish this mode of expressing the energy peculiar to liying 

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."

Iii 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 morphological 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 characters. Each individual is then a particular species or belongs to a particular 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 determines to Avhat species and genus the individual belongs. But the 

individual also starts as a germ and becomes an adult, and as an individual 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 COEEELATION 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 littleness 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 conceived 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 comparative 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 endurance qualities of the organisms whose fossil remains are examined.

The definition of terms was given in a previous paper a, an extract . 

of which Avill 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 accumulating 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 be based upon the life endurance of an individual organism; the amount of

"Jour. Geol., Vol. IX, p. 579. . i
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 lifehistory 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 consectitively 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 .............^........................... 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 certain test of individual characteristics when taken alone, because the 

conditions of preservation, wo 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 number must be in relation to the number of other species preserved at 

the same time under the same conditions. It is the relative abundance 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 component 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 the dominant 

species of the particular faunule. The adjustment of equilibrium 

among the species with each other and with the environment is such a 

complex and delicate matter that it is preserved for each faunule for

Bull. 210 03 9
130 COBEELATION 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 lieinera. The visible expression of the hem era is the temporary faunule, the analysis 

of which into its constituent species constitutes the faunule list of a 

particular locality (geographically) and particular zone (stratigraphically).

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 may be expressed mathematically by recording 

the number of times of appearance. These will then stand as numerators of fractions of which the denominator is the total number of 

faunules listed.

. When the faunules are 'from the same formation, but from separate stations, the statistics .will show the frequency 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 meant 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 which 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 faunal combination 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, distribution, 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 fan miles in this paper that a new definition of a fauna is required 

which shall not be dependent upon formation boundaries. The following points should be included in such a definition: For paleontology 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 by 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 Tropidolepius 

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 eacli 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 an d from a definite geographical position. A faunule will 

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 

adjusted to a particular set of environmental conditions, which, 

though not known, may be to some degree inferred by the character of 

the sediment in which it is found. It is often observed, however, 

that successive faunules in a column of strata differ greatty, 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 \vhich 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. But 

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 Paracydas lirata faunule) when the analysis
132 COBRELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

has been made and the character of the f aunule has been f ulty established.

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 recurrence of the species and its associates in the midst of the Spirifer 

disjundus 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 Tropidoleptus carinaius fauna is used the term includes not only all the 

species normally associated with Tropidoleptus carinaius in its distributional 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, including 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 may 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.

Qeochron. 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 preservation 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 (Hypotliyris) 

cuboides. . Epoch. The name of a dibiochron, indicating the time equivalent of the endurance 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 corresponds to the Acadian formation of the Cambrian system.

«The discrimination of time values in geology: Jour. Geol., Vol. IX, 1901, pp. 570-585. 

bLoc. cit.; pp. 583-584.
WILLIAMS.] VALUE OF FOSSILS. 133

Era. May be used to indicate a tetrabiochron; 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 

Trilobite 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 basis of 

the bionic values of fossils.

Eon.

Trilobite

Period.

7. Phillipsian ._-_._.

4. Asaphian .........

3. Olenian ..........

\ . Qlenellian ........

Epoch.

j Logani ............

[Marionensis .......

("Disjunctus ........

Mucronatus.......

Macropleurus .....

1 Radiatus ..........

(?)

| (?) ' '

Formational equivalent 

(approximate).

Coal Measures.

Keokuk, Burlington.

Kinderhook.

Chemung.

Hamilton.

Corniferous.

Oriskany.

Lower Helderberg 

Waterlime, etc.

Niagara, etc.

Ordovician.

Cambrian.

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 subjected to analysis.

The several faunas under consideration are the measures of epochs 

according to this scheme. We have thus: Tropidoleptus carinatus 

epoch, Grlyptocardia speciosa epoch, Productella speciosa epoch, Spirifer disjunctus epoch.

Regarding these faunas and the time epochs indicated by them, it 

lias been demonstrated that the range of time indicated bjT 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 the 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.
1.34 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 expression 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 stratigraphical 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 paleontology 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 proposed 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 predict in what manner their actual time limits will be defined or discriminated, but enough light has already been thrown upon the 

matter to show that it will be by means of the history which organisms have expressed in their continuous life and evolution that we 

may expect ultimately to mark off the stages of geological time.
BIBLIOGRAPHY.

/ 

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 part of the statistics herein elaborated and discussed. To this list the reader is referred 

for details and particulars, and for authority for facts which are 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 County, New York.

Fifth Ami. Rept. State Geologist of New York, 1886, p. ] 1, 

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. 432-430. 

Chamberlin, T. C. A group of hypotheses bearing on climatic changes.

Jour. Geol., vol. 5,1897, 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 constitution of the atmosphere. 

Jour. Geol., vol. 6, 1898, pp. 609-621.

Clarke, J. M. A brief outline of the geological succession in Ontario County, 

New York, to accompany a map. 

Fourth Ann. Eept. State Geologist of New York,. 1885, 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. Kept; State Geologist of New Yovk, 1889, pp. 02-91.

 A list of the species constituting the known fauna and flora of the Marcellus epoch in New York.

Eighth Ann. Rept. State Geologist of New York, 1889, pp. (iO-(il.

 The fauna with Goniaiites intumescens Beyrich.

Am. Geol., vol. 8,1891, pp. 86-105.

: Die Fauna mit Goniatites intumescens im westlichen New York.

Neues Jalirb. fin- Min., Band 1,1891. pp. 1.01-186.

 The " Hercyn-frage " 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 (Naples 

beds) of western New York and its geological significance.

Am. Jour. Sci., 3d series, vol. 43, 1892, pp 57-64, plate.

 The succession of the fossil faunas in the section of the Livonia salt shaft. 

Thirteenth Ann. Rept. State Geologist of New York, vol. 1, Geology, 1893, pp. 131-158.

 The stratigraphic and faunal relations of the Oneonta sandstones and 

shales, the Ithaca and Portage groups in central New York.

Fifteenth Ann. Rept. State Geologist of New York, Albany, 1897, pp.- 27-81.

135
136 CORKELATION 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 Sihirian 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 stratigraphic 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 formations in eastern New York.

Forty-seventh Ann. Rept. New York State .Museum, 1894, pp. 323-422, 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 Skunnernurik Mountain. New York. 

Bull. Geol. Soc. Am., vol. 5, 1894, pp. 367-394, pi. IT.

Fair-child, H. L. A section of the strata at Rochester, N. Y.. as shown by a deep 

boring.

Proc. Rochester Acad. Sci., vol. 1,1891, pp. 182-186.

Fletcher, H. Geological nomenclature in Nova Scotia.

Trans. Nova Scotia lust. Sci , vol. 10, 1900, pp. 5135-244.

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. 233-339.

 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 Spiriferiiia, 

Syringothyris, Cyrtia, and Cyrtina.

Bull. Geol. Soc. Am., vol, 1,1890, pp. 567-568.

Harris, G. I). 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. 333-345.

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. Paleout., vol. 3. No. 12, June 5, 1899, pp. 1-111.
BIBLIOGKRAPHY. 137

Marcou, Jules. Some remarks on Prof. Henry S. Willianis's report of the subcommittee on the Upper Palaeozoic (Devonic). 

Ain. G-eol., vol 2,1889, pp. 60-61.

Miller, S. A. North American Mesozoic and Cenozoic Geology and Palaeontology. (And supplements.) 1889.-1897.

Prosser, C. S. Section of the Lower Devonian and Upper Silurian strata of central New York as shown by deep well at Morrisville. 

Proc. Am. ASSOQ. Adv. Sci., vol. 36,1888, pp. 208-209.

 The Uppei Hamilton of Chenango and Otsego counties, New York.

Pvoc. Ain. Assoc. Adv. Sci., vol. 36,1888, p. 210.

 The classification and distribution of the Hamilton and Cheiimng 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 Skunnemunk Mountain, Orange County, N. Y. 

Trans. New York Acad. Sci., vol. 11,1892, pp. 132-149.

 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. 49-104.

 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 Unadilla 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 Chernung series

of central and eastern New York. Part I.

Fifteenth Ann. Rept. State Geologist of New York,J895, pp. 87-225. 

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. 1-464.

 - Lower Devonic aspect of the Lower Helderberg and Oriskany formations.

Bull. Geol. Soc. Am., vol. 11,1900, pp. 241-332.

Sherzer, W. H. Geological report on Monroe County, Mich.

Geol. Surv. Michigan, vol. 7, part 1, pp. 1-240, pis. xvii, 8 figures, including 3 colored maps.

Stevenson, J. J. The Chernung 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 Milwaukee, Wis. 

Jour. Geol., vol. 7,1899, pp. 272-283.
138 COEEELATION OF GEOLOGICAL FAUNAS. [BULL. 210.

"Weller, Stuart. The succession of fossil faunas at Springfield, Mo. 

Am. Jour. Sci;, 3d series, vol. 49,1895, pp. 185-199.

 : A circum-insular Paleozoic fauna. 

Jour. Geol., vol. 3, 1895, pp. 903-917.

 Con-elation of the Devonian faunas in southern Illinois. 

. Jour. Geol., vol. 5,1897, pp. 625-635.

 Classification of Mississippian series. 

Jour. Geol., vol. 6,1898, 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. Eept. State Geologist New Jersey for 1899,1900, pp. 1-53.

 The succession of fossil faunas in the Kinderhook beds at Burlington, Iowa. 

Iowa Geol. Surv., vol. 10,1900, pp. 63-79. .

 Correlation of the Kinderhook formations of southwestern Missouri.

Jour. Geol., vol. 9,1901, pp. 130-148.

Williams, H. S. The life history of Spirifer kevis Hall; a paleontological study. 

Ann. New York Acacl. Sci., vol. 2, pp. 140-160, pi.'xiv.

 The recurrence of faunas in the Devonian rocks of New York. 

Proc. Am. Assoc. Adv. Sci., vol. 30,1882, pp. 186-190.

 Catalogue of the fossils of the Chernung period of North America.

14pp., Ithaca, N.Y.

 On a remarkable fatina 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. 34,1886, 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 Strophomenidse; a paleontological study of the method of initiation 

of genera-and species. . .

Proc. Am. Assoc. Adv. Sci., vol. a5,1887, 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, vpl. 35,1888, pp. 51-59.

 Report of the subcommittee on the Upper Paleozoic (Devonic). International Congress of Geologists. 

Philadelphia, 1888, pp. cl-c31,

 On the relations of the Devonian faunas of Iowa. 

Am. Geol., vol. 3,1889, pp. 230-233.
BIBLIOGRAPHY. 139

Williams, H. S. The Cuboicles zone and its fauna; a discussion of methods of 

correlation. 

Bull. Geol. Soc. Ani., vol. 1,1890, pp. 481-501, pis. xi-xiii.

 Correlation paper, Devonian and Carboniferous. 

Bull. U. S. Geol. Survey No. 80,1891, pp. 1-279.

 The scope of paleontology and its value to geologists.

Proc. Am. Assoc. Adv. Sci., vol. 41,1892, pp. 149-170. Am. 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. 11,1900, 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. Contrrtrations 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. Kept. .State Geologist of New York, 1887, pp. 10-12.

 The Tully limestone, its distribution and its known fossils. 

Sixth Ann. Bept. 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........ 83,80

Amboccelia umbonata, occurrence of...... 51,

50,57, 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 fannule, 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

33.

Barclay coal fauna; geologic place of...... 47

Barrande's theory of "colonies," observations on .............................. 31,34

Bedford shale stage or faunule, geologic

place of............................... 48

Beecher, C. E., aid by ...................... 49

Bellerophon leda, occurrence of........... 64

Bellerophon mara, occurrence of.......... 96

Benthos, definition of....:................. 14

Berea grit, faunule of ...................... 48

Bibliography ........................I.... 135-139

Biochron, definition of.................... 31,132

Bion, definition of......................... 127

Bionic classification, scheme of ............ 30

Bionic 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

stratigraphic equivalents of............ 99

Black shales fauna, geologic place of ...... 47

stages or fauuules of ................... 47

Botanical classification, principles of...... 15-16

C.

Page.

CarnarotCEchia. See also Rhynchonella. 

Camarot03chia alleghania, occurrence of.. 88 

Camarotcechia contracta, occurrence of.... 83,

85,86,87,88,91,94,96

Camarotcechia contracta saxatilis, occurrence of .............................. 79

Camarotcechia duplicata, occurrence of.... 86

Camarotcechia eximia, occurrence of ...... 74,

76,77,88,96

Camarotoechia orbicularis, occurrence of.. 88

Camarotcechia 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.. 64-66 

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

fauna! shifting coincident with deposition 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....... 50

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 formations, limits of..... J.................. 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, Chenango County, New York............ 94

cited on mingling of species of adjacent 

faunas................................ 103

cited on Oneonta and Portage sandstones, 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................. 9,49,54-55

cited on Hamilton fauna of Cayuga 

Lake. .............. ................... 80

Cleveland shale, stratigraphic place of..... 47

Coleolus acicula, occurrence of............. 77,90

Coledlus tenuicinctum, occurrence of.... .. 95

"Cornell University, work done at... 6,7,8,9,43,46 

Correlation, geologic, diverse data employed

for................l................. 117-120

importance of.............. .'. .......... 10

work done in........................... 10

Correlation and mutation of faunas, discussion of ............................ 81-82

Cryphseus 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 shale and sandstone, faunule of. 48

Cypricardella bellistriata, occurrence of... 74,

' 77,82,90,91,95

Cypricardella complanata, occurrence of.. 95 

Cypricardella gregaria, occurrenceof. 76,77,95,96

Cyrtia. See Spirifer altus.

Cyrtina hamiltonensis, occurrence of... 74,91,95

Cystiphyllum, occurrence of............... 67

3D.

Call, W. H., and Harris, G. D., 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 equivalents of............................... 122

Delthyris mesicostalis, occurrence of...... 61,

70,72,83,85,86,88,91,94,95,96 

See also Spirifer mesicostalis. 

Devonian formations, dissection and analysis 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, fatinal classification of,

introduction of....................... 45-48

Dewalque, G., cited........................ 28

Diaphorostorna lineatum, occurrence of. ... 64

Discina fauna, geologic place of ............ 45

Disjunctus fauna. See Spirifer disjunctus. 

Distribution, geographic; of faunas, observations on ....................'........ 16-20

Dual nomenclature in geology, suggestions

concerning ........................... 11-13

title of paper on ........... ............. 12

Ectenodesma birostratum, occurrence of . . 96 

Edmondia philipi, occurrence of ........... 96

Eighteenmile 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, determination 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 environment. ........................... 113

biologic equilibrium of, conditions favoring .............................. 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

faeies of ................................ 35

.integrity of, conditions favoring ..... 105-108

local expressions of .................... 25

migration of. ..... 18, 23-24, 31-32, 34-41, 97-116

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 consequences of . 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

valueof,astimeindicatorsingeology. 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. 38
INDEX. 143

Page 

Fossiliferous 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

&. (

Gciger, 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

Gcochron, 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

Gly tocardia 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 frbmEighteenmileCreek, 

New York............................ 92

cited on Hamilton fauna of Eighteenmile Creek ........................... 80

cited on Hamilton fauna of Michigan.. 65 

Grammysia, occurrence of................. .90

Granimysia 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

Haeckel. Ernst, names for biologic aggregates proposed by.................... 14

Hall, James, cited on Glyptocardia (Cardiola) 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. 45,

47,50,122,123

thickness of ............................ -93

Harris, G. D., aid by.:...................... 9,49

cited on fauna of the Chemung formation................................... 85-86

Harris, G. P., and Dall, Vf. H., work in

geologic correlation done by......... 10

Heliophylluni 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

Holoneina rugosa, occurrence of........... 96

Homeotopic, term proposed.............50 (note)

Huron shales, equivalents of............... 122

Huxley, T. H., cited ....................... 33

Hypothyris cuboides, occurrence of........ 78

I.

Illinois, Hamilton formation in, fauna of.. 66 

Indiana, Tropidoleptus carinatus fauna in. 66-67 

International Congress of Geologists, extract from Compte Rcndu 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 di versa, occurrence of ................ 72, 95

Leiopteria bigsbyi, occurrence of .......... 90, 95
144 INDEX.

Page. 

Lciopteria rafinesquii...................... 96

Leiorhynchus fauna, geologic place of..... 46

Leiorhynchus globuliforme, occurrence of. 96,98 

Leiorhynchus globuliforme stage or faunule, 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

Le pdodesma 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, geologic place of....................... T . 47

Lingula spatulata stage or faunule, geologic 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.

Macrodoii hamiltonise, occurrence of...... 90

Mackenzie River Valley, faunas of, relations 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 expression 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 my tiloides, occurrence- of... 90 

Modiomorpha 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 discussion of............................. 17,81-82

Myrtilarca carinata, occurrence of......... 90

Mytilarca chemungensis, occurrence of. 85,86,87

3ST.

1'apa 

Necton, definition of ....................... 14

Nucula bellistriata, occurrence of.l........ 51,

56, 58, 59, 60, 62, 63, 75 

Nucula corbuliformis, occurrence of ....... 61,

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

f aunal shifting in ................. 97-103, 115

geologic horizon of, variation of, in different localities ............... '. .... 108-109

. shifting of faunas coincident with deposition 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 (=Schizophor,ia) , 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, occurrence of ........................... 92

Owego, N. Y., fossils found at ............. 89-90

Palteanatina typa fauna, formation containing ............................... 46, 48
INDEX. 145

Page. 

Palseoneilo, occurrence of.................. 90

Palreoneilo brevis, occurrence of........... 9G

Palseoneilo brevis quadrangularis, occurrence 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

Palffioneilo filosa, occurrence of......... 72,74,95

Paloeoneilo plana, occurrence of........... 95

Panama conglomerate; stratigraphic equivalent of.:........'..................-... 122

Papers and books consulted, list of....... 135-139

Paracyclas 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

PleurotOinaria 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.......... no

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 correlation.. ................................. 10

Primitiopsis punctilifera, occurrence of. 57,58,64 

Productella costatula, occurrence of....... 87

Productella (dissimilis) hallana, occurrence of.............................. 78,79

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 predecessor 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 successor 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 03 10

Page. 

Prosser, C. S., cited on post-Oneonta fauna

of eastern New York................. 93-94

work done by .......................... 8

Proetus canaliculatus, occurrence of....... 67

Prothyris lanceolata, occurrence of........ 72,77

Pterinea, occurrence of.................... 90

Pterinca chemungensis, occurrence of..... 83,86

Pterinopecten, occurrence of.............. 91

 Pterinopecten crenicostatus, occurrence of. 91 

Pterinopecten suborbicularis, occurrence 

of......................................... 77

Pugnax pugnus, occurrence of....... 78,79,88,96

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 

Roemcrella 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 iovvensis, 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), occurrence of .............................. 83,86
146 INDEX.

Schuchert, Charles, cited on brachiopods

of the Chemung fauna............... 85

Sediments, different classes of, limited distribution of........................... 113

Sellersburg formation, equivalents of...... 123

fossils of................................ 66-67

Shales, variability of fossils of.............. 33

Sherburne formation, geologic horizon of. 112,122 

thicknessof ............................ 93

Shifting of faunas, biological consequences

of................................... 105-108

effect of, on classification of formations ............................... 108-116

evidenceof............. .............. 97-103

observations on......................... 18

principles involved in................ 103-105

South America, Devonian faunas of, relations of............................... 79

Species, definition of term ............... 127-130

life endurance of....................... 30-31

mutation of ......................... 1", 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,

78,83,85,86,87,88,89,91,94,96,122 

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 (Reticularia) Isevis, occurrence of.. 78 

Spirifera Itevis stage or faunule, geologic

place of............................ 45;.47,69

Spirifer marcyi, occurrence of .......... 88,90,91

Spirifer medialia, occurrence of............ 62

Spirifer (Delthyris) mesicostalis, occurrence 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, geologic place of......................... 47,82

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, geologic 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. disjunctus.

Spirigera concentrica (=Athyris' spiriferoides) occurrence of.................. 65

Stevenson, J. J., aid by..................... 49

Stictopora, occurrence of................... 07

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 perplaua, occurrence of .... 56,

67,58,63,67 

Stropheodonta variabilis, occurrence of.... 79

Strophonella reversa, occurrence of........ 79

Succession of faunas, methods of......... 105-108

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 carinatus, occurrence of .... 51,

56, 59, 60, 61, 62, 63, 64, 67, 71, 

72,75,76,82,89,90,91,95,96 

Tropidoleptus carinatus fauna, definition of

term. . .............................. 131-132

. distributional values of species composing ................................... 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 ...:......... 61, 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 Pennsylvania ............................. 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

U.

Unadilla region, fauna of . 62

Van Hise, C. R., work in geologic correlation done by.......................... 10
INDEX. 147

Page.

Van Ingcn, Gilbert, acknowledgments to.. 9 

work clone by .......................... S

Variation of specific forms, conditions influ- 

. ' encing................................ 35-36

definition of............................ 17

Verrill, A. E., cited on adjustment of faunas

to local conditions ................... 106

 "w.

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........................... 14

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 .......................... S

Page. 

White, C. A., work in geologic correlation

done by .............................. 10

Whiteaves, J. F., cited on fauna of Hamilton formation of Ontario, Canada.... CO, 61

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 ............. 05-66

Williams, S. G., aid by...................... 49

Wolf Creek conglomerate, fauna of........ 48

Yale University, work done by students of. 8,9,43

Zones, fossiliferous, features of............. 20-23

subdivisions of.......................... 21

transgression of........................ 23

Zoological classification, principles of...... 15-16

0

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 Resources, (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 maybe had on application.

The Bulletins, Professional Papers, and Water-Supply Papers treat of a variety of subjects, 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 physics; 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. Ellsworth 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. White. 1885. 33 pp.

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19. Notes on the stratigraphy of California, by G. F. Becker. 1885. 28 pp. (Out of stock.) 

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1885. 33G pp.

29. Fresh-watf r 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. 369pp., 33 pis. (Out of stock.)

31. Systematic review of our present knowledge of fossil insects, including myriapods and arachnids,

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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. 18b7.

121 pp., 4 pis. 

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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

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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; 744pp.

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80. Correlation papers Devonian and Carboniferous, by H. S. Williams. 1891. 279 pp.

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87. Synopsis of American fossil Brachiopoda, including bibliography and synonymy, by Charles 

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93. Some insects of special interest from Florissant, Colo., and other points in the Tertiariesof Colorado 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. 

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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. 

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105. The Laramie and the overlying Livingston formation, in Montana, by W. H. Weed, with report 

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206. A study of the fauna of the Hamilton formation of the Cayuga Lake section in central New

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210. The correlation of geological faunas, a contribution to Devonian paleontology, by H. S. Williams.

1903. 147 pp., 1 pi.
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Williams, Henry Shaler.

. . . The correlation of geological faunas, a contribution to Devonian paleontology; by Henry 

Shaler Williams. Washington, Gov't print, off., 

1903.

147, III p. 1 pi. 23iom . (U. 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 contribution to Devonian paleontology; by Henry 

Shaler Williams. Washington, Gov't print, off., 

1903.

147, III p. 1 pi. 23iom . (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 geological faunas, a contribution to Devonian 

paleontology. 1903

U. S. Dept. of the Interior.

see also 

U. S. Geological survey.

in