deposits would lead to a division into distinct epochs more numerous;
but I think that, in the meantime, the division into three principal
epochs, which I shall designate, with the majority of geologists, by
the names Eocene, Miocene, and Pliocene, is sufficient for a
comparison of the successive changes of the vegetable kingdom. I shall
point out for each of them the localities which I think should be
comprehended under these different designations.
"With regard to the general characters which result from the
comparative examinations of these Floras, we find that the number of
species, in the great divisions, are thus distributed in these three
Floras:--
Eocene Miocene Pliocene
Epoch. Epoch. Epoch.
-------- -------- --------
Cryptogams, 33 ... 10 ... 13 ...
Amphigenous, ... 16 ... 6 ... 6
Acrogenous, ... 17 ... 4 ... 7
Phanerogams, ... ... ... ... ... ...
Monocotyledons, 33 33 26 26 4 4
Dicotyledons, 143 ... 97 ... 195 ...
Gymnosperms, ... 40 ... 19 ... 31
Angiosperms, ... 103 ... 78 ... 164
--------- -------- --------
Total, 209 ... 209 ... 212 ...
"It may only be remarked that, in the first column, or Eocene
formation, the fossil fruits of the Isle of Sheppey--a part only of
which have been described by M. Bowerbank--have a great influence on
the numbers of the different divisions of Phanerogams, and that this
locality appears altogether exceptional, and is, perhaps, an example
of the effect of currents conveying exotic fruits from remote
climates, and accumulating them on a point of the shores of Europe.
"In this point of view, the enumeration of the plants of this first
epoch is in no way comparable to that of the other epochs, where I
have refrained even from introducing the small number of fossil plants
from the Tertiary formations of the equatorial regions that are known,
in order to confine myself to a comparison of the Tertiary Floras of
Europe.
"With regard to the characters drawn from vegetable forms during these
three epochs, the most remarkable appear to me, 1_st_, In the Eocene
period, the presence, but rarity, of the palms, limited to a small
number of species.
"The predominance of Algæ and marine Monocotyledons, which must be
ascribed to the great extent of marine formations during this epoch.
"The existence of a great number of extra European forms, resulting
especially from the presence of the fossil fruits of Sheppey.
"2_d_, In regard to the Miocene epoch, the abundance of palms in the
greater number of localities belonging, without doubt, to this epoch;
the existence of a considerable number of non-European forms, in
particular of the genus _Steinhauera_, which appears to me to be a
rubiaceæ allied to _nauclea_, found in many localities of these
formations.
"3_d_, In regard to the Pliocene epoch, the great predominance and
variety of Dicotyledons, the rarity of Monocotyledons, and, above all,
the absence of Palms; lastly, the general analogy of the forms of
these plants with those of the temperate regions of Europe, North
America, and Japan.
"A remarkable character of the Floras of these three epochs, but which
is most striking in regard to the last, in which the dicotyledonous
plants are most numerous, is the absence of the most numerous and
characteristic families of the division of Gamopetalis. Thus, among
the numerous impressions of Partschlug, OEningen, Hoerring, Radoboj,
&c., there is nothing to indicate the existence of the Compositæ,
Campanulaceæ, Personneæ, Labiaceæ, Solaniæ, Boraginaæ, &c.
"The only Monopetales mentioned in great numbers are the Ericaceæ,
Ilicineæ, some Sapotaceæ, and Styraceæ, families which belong almost
as much to the Dialypetales as to the Gamopetales.
"In the Miocene flora only have been pointed out many Apocyneæ, and
Rubiaceæ, which I have mentioned above.
"1. _Eocene Epoch._--This epoch, in the most precise limits,
comprehends plastic clay with its lignites, the coarse Parisian
limestone and gypsum which lie above it in the same basin; but I have
not thought it worth while, in the meantime, to separate from it some
formations which, according to the investigations of modern
geologists, are placed between the Cretaceous formations and the
inferior parts of the formations mentioned; such are the Nummulitic
formations of the Vicentin, comprehending the celebrated locality of
Monte-Bolca, and probably some others near it, such as Salcedo, in the
Vicentin. I have likewise joined to this Flora of the Eocene
formations a very remarkable locality of the basin of Paris, the
relations of which with the Tertiary beds are not yet perfectly
determined,--these are the beds of a species of ancient Travertin
which, near Sezanne, contain numerous fossil vegetables still
undescribed, and of which I shall here notice the most remarkable.
These plants have very peculiar remains, and belong probably to a
special Flora, unless the differences can be ascribed to a diversity
of station.
"Besides the different members of the Eocene formation, properly so
called, of the Paris basin, I comprehend in this Flora the fossils of
the same formation in England, at the Isle of Wight, and Isle of
Sheppey in the London basin. These latter fossils, consisting almost
solely of fruits transformed into pyrites, constitute a whole which
has no analogue in any other of the Tertiary basins of Europe; not
only in the number and diversity of these fruits, but in their
peculiar characters, which remove them widely from the plants whose
leaves occur in the other beds of the same geological epoch.
Everything, therefore, would lead us to suppose that these fruits,
although belonging to plants cotemporaneous with the Eocene deposits
of Europe, have been brought from distant countries by marine
currents, just as fruits are still brought from the equatorial regions
of America to the coasts of Ireland or Norway by the great current of
the Atlantic. The deposit in the Isle of Sheppey appears therefore to
be an accidental case in the Eocene deposits, and the Paris basin
presents none of these fossils.
"The Tertiary basin of Belgium, which follows that of London, has
yielded, near Brussels, some fossil fruits in very small numbers, but
which appear identical with one of the genera most abundant at
Sheppey. This is the _Nipadites_, considered at first as a species of
Coco, under the name of _Cocus burtini_.
"Lastly, following the advice of my learned associate, M. Elie de
Beaumont, I have included in the same Flora the plants contained in
the Lignites of the shores of the Baltic and Pomerania, so rich in
amber, in which these vegetables have often been preserved. It is to
the labours of M. Goeppert that we are indebted for a knowledge of
these vegetables, most frequently represented by very small fragments,
the relations of which he has determined with much skill and
accuracy."
With materials collected in these various localities, but of which the
greater part are still unpublished, we may construct the Flora of the
Eocene epoch; but the list, comprehending only the species described,
or at least determined, is only a mere sketch.
M. Brongniart then gives the names of the vegetables belonging to the
Eocene epoch; these are, for the Amphigenous cryptogams, algæ, and
mushrooms; for the Acrogenous cryptogams, hepatici, mosses, ferns,
equisetaceæ, and characeæ. The Monocotyledons present Naiades,
Nipaceæ, and palms. The Gymnospermous dicotyledons are represented by
Coniferæ (Cupressinæ, Abietineæ, Taxineæ, and Gnetaceæ.) Lastly, among
the Angiospermous dicotyledons, we find examples of Betulaceæ,
Cupuliferæ, Juglandeæ, Ulmaceæ, Proteaceæ, Leguminosæ, OEnothereæ,
Cucurbitaceæ, Sapindaceæ, Malvaceæ, Ericaceæ, and three doubtful
families (Phyllites, Antholithes, and Carpolithes.)
"The most remarkable characters of this Flora are,--
"1_st_, The great quantity of Algæ and marine Naiades, characters
owing to the extent and thickness of the marine formations of this
epoch.
"2_d_, The great number of Coniferæ, the greater part belonging to
genera still existing, but among which the Cupressineæ appear to
predominate, especially if we admit as positively belonging to this
family the various fruits of the Isle of Sheppey, which M. Bowerbank
has described under the name of Cupressinites, and of which M.
Endlicher has formed the genera Callitrites, Frenelites, and
Solenostrobus. If these fruits really belong to European vegetation,
they indicate very peculiar generic forms, probably now wholly
extinct.
"3_d_, The existence of many large species of palm, equally shewn by
the occurrence of their leaves and stems.
"2. _Miocene Epoch._--This Eocene or middle epoch of the Tertiary
formations appears to me to comprehend the following localities among
those which have furnished materials for the study of the vegetation
of the Tertiary period: 1_st_, In the environs of Paris, the superior
sandstones, or those of Fontainebleau and the _Meulieres_, or
Buhrstone, which crown our coasts; 2_d_, The sandstone, with
impressions, in the environs of Mans and Angers, and probably those of
Bergerac, in the department of the Dordogne; 3_d_, A part of the
Tertiary formations of Auvergne, and particularly those of the
mountain Gergovia, formations which, by their impressions, appear more
ancient than those of Menat, but which perhaps all belong to different
stages of the Pliocene epoch; 4_th_, The fresh-water formations of
Armissan, near Narbonne, the Gypsum of Aix in Provence, the Lignites
of Provence, whose vegetable fossils are scarcely known; finally, the
Lacustrine formations, rich in the wood of palms, and in stems of
Monocotyledons, from Upper Provence, near Apt and Castellane; 5_th_, A
part of the Tertiary formations of Italy, and particularly those of
Superga, near Turin; 6_th_, The Mollasse of Switzerland, with its
Lignites, at Lausanne, Koepfnac, and Horgen, containing the remains of
palms; 7_th_, The Lignites of the banks of the Rhine near Cologne and
Bonn, at Friesborf, Liblar, &c., sometimes enclosing wood of palms,
and those of Wetteravia at Nidda, near Frankfort, and other places; as
well as those of Weisner near Cassel, which all appear to be of the
same epoch, although those of Wetteravia, by the abundance of certain
genera of Dicotyledons, such as _juglans_ and _acer_, and even by many
cases of specific identity, seem to make a nearer approach to the
Pliocene flora; 8_th_, A part of the Lignites of Bohemia, and
particularly those of Altsattel, whose fossils, described by M. de
Sternberg and M. Rossmæssler, generally agree with those of the other
localities already mentioned. The other Lignites of Bohemia, those of
Bilin and of Comothau in particular, enter completely into the
Pliocene flora; 9_th_, Hoerring in the Tyrol, and Radoboj in Croatia,
of which M. Unger has so well described the numerous impressions in
his _Chloris Protogæa_, and which have almost become the type of the
Miocene flora.
"With the exception of the Lignite formations of the neighbourhood of
Cassel and Frankfort--the species of which have often numerous points
of connection with those of OEningen and Parschlug, and which enter
rather into the Pliocene flora--the different localities I have
mentioned have numerous relations between them as to their fossil
vegetables. Thus, the Nymphea Arethusæ is found in the _Meulières_ or
Buhrstone of Paris, and in the marls of Armissan; the Flabellaria
rhapifolia and maxima recur at Hoering in the Tyrol, at Radoboj in
Croatia, and in the superior sandstones of the environs of Angers and
Perigneux.
"The Callitrites Brongniartii, Endl., is likewise met with in the
formations of Armissan, Aix, in Provence, at Hoering and Radoboj.
"Lastly, the Steinhauera globosa of the Altsattel Lignites in Bohemia,
is likewise found in the sandstone of the vicinity of Maus; and the
Platanus Hercules of Radoboj, in Croatia, has been sent to me from
Armissan, near Narbonne, by M. Toumal.
"These facts would probably multiply by a more attentive study of the
different localities; but as it is, they leave little doubt as to the
synchronism of the greater part of these local formations."
In the Flora of the Miocene formations, Amphigenous cryptogams occur,
represented by Algæ and mushrooms; Acrogenous cryptogams, represented
by mosses, ferns, and Characeæ; Monocotyledons, among which we find
Naiades, Gramineæ, Liliaceæ, and Palms; of the Gymnospermous
dicotyledons, Coniferæ; and Angiospermous dicotyledons, among which
occur Myriceæ, Betulineæ, Cupuliferæ, Ulmaceæ, Moreæ, Plataneæ,
Salicineæ, Lawrineæ, Umbelliferæ, Karolangeæ, Combretaceæ,
Calycantheæ, Leguminosæ, Anacardiæ, Xanthoxyleæ, Juglandeæ, Rhamneæ,
Acerineæ, Nympheaceæ, Apocyneæ, and Rubiaceæ.
"The most striking characters of this epoch consist of the mixture of
exotic forms at present peculiar to regions warmer than Europe, with
vegetables growing generally in temperate countries; such as the
palms, a species of bamboo, Lawrineæ, Combretaceæ, Leguminosæ of warm
countries, Apocyneæ, analogous, according to M. Unger, to the genera
of equatorial regions, a Rubiaceæ altogether tropical, united with
_erables_, walnuts, birches, elms, oaks, _charmes_, &c., genera proper
to temperate or cold regions. The presence of equatorial forms, and
particularly of palms, appears to distinguish this epoch essentially
from the following one. Lastly, we likewise observe the very small
number of vegetables with a monopetalous corolla, limited to species
referred to the family of Apocyneæ by Unger, and to the genus
Steinhauera, founded on a fruit which has much relation to that of
Nauclea among the Rubiaceæ.
"3. _Pliocene Epoch._--This epoch, embracing all the Tertiary
formations superior to the _fahluns_ of Touraine, comprehends pretty
numerous localities rich in fossil vegetables, and whose position in
these formations is determined as much by the _ensemble_ of the
vegetables they contain, as by their other geological characters. The
Tertiary basins which, it appears to me, must serve as the basis of
this Flora, both by their identity, and the numerous and
carefully-studied vegetables they contain, are: 1st, That of OEningen,
near Shaffouse, the species of which have been long since studied and
well determined by M. Alex. Braun, whose work, though unpublished, has
been communicated to many naturalists, and particularly to M.
Unger.[44] 2_d_, That of Parschlug, in Styria, the numerous
impressions of which M. Unger has collected, studied, and determined,
partly published by him in his _Chloris Protogæa_, and presented
altogether in a special enumeration of these species recently
published under the title of _Flora of Parschlug_. In this locality
alone, M. Unger has recognised and classified 140 different species;
it is the most numerous local Flora with which we are acquainted, and
the identity of a great number of species with those of OEningen,
indicates well the synchronism of these two local formations. Such
other points in Styria appear likewise to be of the same epoch, as
well as many localities in Hungary so rich in silicified wood. In
Bohemia, the tripoli slates of Bilin and Comothau, which contain a
pretty considerable number of plants described by M. de Sternberg, are
no doubt referrible to this epoch, according to the nature of these
plants. Lastly, the Tertiary hills, called the sub-appennine hills of
Plaisantin, of Tuscany, and a part of Piedmont, as well as the
gypseous formation of Stradella, near Pavia, so rich in impressions of
leaves, form part of this epoch; but, with the exception of this
latter point, these formations contain, in general, few vegetables.
Footnote 44: The following interesting observations on the
OEningen formation are by Professor Agassiz, who refers it to the
Miocene not to the Pliocene class:--
"This picture would be incomplete did I not institute a farther
comparison between the present vegetation of those regions and
the fossil plants of modern geological epochs. If we compare,
namely, the Tertiary fossil plants of Europe with those living on
the spot now, we shall be struck with the differences of about
the same value as those already mentioned between the eastern and
western coasts of the continents under the same latitudes.
Compare, for instance, a list of the fossil trees and shrubs from
OEningen, with a catalogue of trees and shrubs of the eastern and
western coasts, both of Europe, Asia, and North America, and it
will be seen that the differences they exhibit scarcely go beyond
those shewn by these different Floræ under the same latitudes.
But what is quite extraordinary and unexpected is the fact, that
the European fossil plants of that locality resemble more closely
the trees and shrubs which grow at present in the eastern parts
of North America, than those of any other part of the world;
thus, allowing us to express correctly the differences already
mentioned between the vegetation of the eastern and western
coasts of the continents, by saying that the present eastern
American flora, and I may add, the fauna also,[A] and probably
also that of eastern Asia, have a _more ancient character_ than
those of Europe and of western North America. The plants,
especially the trees and shrubs growing in our days in this
country and in Japan, are, as it were, old fashioned; they bear
the mark of former ages--a peculiarity which agrees with the
general aspect of North America; the geological structure of
which indicates that this region was a large continent long
before the extensive tracts of land had been lifted above the
level of the sea in any other part of the world.
"The extraordinary analogy which exists between the present Flora
and Fauna of North America, and the fossils of the Miocene period
in Europe, would also give a valuable hint with respect to the
mean annual temperature of that geological period.
"_OEningen_, for instance, whose fossils of all classes have
perhaps been more fully studied than those of any other locality,
could not have enjoyed, during that period, a tropical or even a
subtropical climate, such as has often been assigned to it, if we
can at all rely upon the indications of its Flora; for this is so
similar to that of Charleston, South Carolina, that the highest
mean annual temperature we can ascribe to the Miocene epoch in
central Europe must be reduced to about 60° Fah.; that is to say,
we infer from its fossil vegetation that OEningen had, during the
Tertiary times, the climate of the warm temperate zone, the
climate of Rome, for instance, and not even that of the northern
shores of Africa. We are led to this conclusion by the following
argument:--The same isothermal line which passes at present
through OEningen, at the 47th degree of northern latitude, passes
also through Boston, lat. 42°. Supposing now (as the geological
structure of the two continents and the form of their respective
outlines at that period seem to indicate), that the undulations
of the isothermal lines which we notice in our days existed
already during the Tertiary period, or, in other words, that the
differences of temperature which exist between the western shores
of Europe and the eastern shores of North America, were the same
at that time as now, we shall obtain the mean annual temperature
of that age by adding simply the difference of mean annual
temperature which exists between Charleston and Boston (12° Fah.)
to that of OEningen, which is 48° Fah., as modern OEningen agrees
almost precisely with Boston, making it 60° Fah.; far from
looking to the northern shores of Africa for an analogy, which
the different character of the respective vegetations would
render still less striking. The mean annual temperature of
OEningen, during the Tertiary period, would not therefore differ
more from its present mean than that of Charleston differs from
that of Boston."--_Agassiz_, _on Lake Superior_, p. 150.
Footnote A: The characteristic genera Lagomys, Cheldyra, and
the large Salamanders with permanent gills, remind us of the
fossils of OEningen, for the present fauna of Japan, as well
as the Liquidambar, Carya, Taxodium, Gleditschia, &c., &c.
"In France, the Pliocene epoch probably comprehends a part of the
fresh-water deposits of Auvergne and Ardêche. Thus, the slates of
Menat and those of Rochesauve appear to me to furnish a Flora very
similar to those of OEningen and Parschlug. With regard to the marls
of Gergovia and Merdogne, near Clermont, I think they ought rather to
be classed in the Miocene epoch; but this question can be settled only
by a more attentive determination of the species. The Flora, which
recapitulates all that has been described or named in these
formations, is, however, essentially founded, as may be seen by the
indication of localities, on the two basins of Parschlug and OEningen.
"The Flora of the Pliocene formations is constituted by Amphigenous
cryptogams, comprehending algæ and mushrooms; by Acrogenous
cryptogams, including a muscite, ferns, lycopodiaceæ, and equisitaceæ;
by Monocotyledons, naiades, gramineæ, cyperaceæ, and liliaceæ; by
Gymnospermous dicotyledons, coniferæ, represented by cupriessineæ,
abietineæ, and taxineæ; finally, by Angiospermous dicotyledons,
comprehending myriceæ, betulaceæ, cupuliferæ, ulmaceæ, balsamifluæ,
salicineæ, laurineæ, thymaleæ, santalaceæ, corneæ, myrtaceæ,
calycantheæ, pomaceæ, rosaceæ, amygdaleæ, leguminosæ, anacardeæ,
juglandeæ, rhamneæ, celastrineæ, sapindaceæ, acerineæ, tiliaceæ,
magnoliaceæ, capparideæ, sapoteæ, styraceæ, oleaceæ, ebenaceæ,
ilicineæ, and ericaceæ.
"The Pliocene epoch, considered in relation to Europe, for I have
intentionally excluded from the preceding list some fossils of the
Antilles referred to these formations, offers as peculiar characters
an extreme analogy to the existing Flora of the temperate regions of
the northern hemisphere; I do not say of Europe, for this Pliocene
flora comprehends many genera strangers in the present time to Europe,
but proper to the vegetation of America or temperate Asia. Such are,
if we admit the accuracy of the generic relations established by the
botanists to whom these determinations are owing, taxodium,
salisburia, comptonia, liquidambar, nyssa, robinia, gleditschia,
bauhinia, cassia, acacia, rhus, juglans, ceanothus, celastrus,
sapindus, liriodendron, capparis, sideroxylon, achras, and symplocos,
all genera foreign to temperate Europe, but in which they have been
found in a fossil state, but which, for the most part, still occur in
the temperate regions of other parts of the globe.
"As to other genera still existing in Europe, but which contain only a
small number of species, we find many more of them in a fossil state;
such are the _Erables_, of which 14 species are enumerated in this
Flora of the Pliocene epoch, and the Oaks, which are 13 in number. It
ought to be remarked, that these species come from two or three very
circumscribed localities which, in the present time, probably would
not furnish, in a circuit of many leagues, more than three or four
species of these genera. Lastly, another character, which I have
already spoken of, and which makes this Flora to differ still further
from that of our epoch, is the absence, or at least the small number
and nature of the plants with Gamopetalous corollas.
"Thus, there are only twenty plants of this Flora arranged in the
families of this division, and all are referrible to this group of
Hypogynous gamopetales, which I have distinguished by the name of
Isogynes; in the general organization of the flowers, they approach
nearest to the dialypetales.
"Is this absence of Anisogynous gamopetales, and with irregular
ovaries, the result of chance; or does it arise from this, that many
of these plants, particularly among the species of temperate regions,
are herbaceous, and that herbaceous plants are generally in conditions
less favourable for passing into a fossil state? Or, lastly, did those
families, which some botanists have been led to consider the most
elevated in organization, not yet exist? These are points which cannot
be positively determined in the present state of our knowledge.