Chapter VI: Fossil Vegetables (4)

In the fossil, _fig. 2. Lign. 65_, from the Isle of Sheppey, the tubes of the teredinæ are seen in relief, in consequence of the surface of the block of wood having decayed and been removed.

Fossil Liliaceæ.--The family of endogens, termed _Liliaceæ_, comprises many beautiful plants; those with annual stems, as the Lily, Hyacinth, Tulip, &c. are well known for the variety and splendour of their blossoms; some of the arborescent forms, as the Tulip-tree, attain a large size, but the flowers of this division are relatively small. In tertiary strata, the stems, leaves, fruits, and even the imprints of flowers, have been discovered, of plants related to _Sagittaria_ (Arrow-head), _Smilax_ (Bind-weed), _Convallaria_ (Lily of the valley), &c.

The Dracæna (_Dragon-blood tree_), a tall, slender, elegant tree with amplexicaul leaves (common in our hot-houses), belongs to this family; and certain stems found with Clathrariæ, and bones of the Iguanodon, in the Kentish-rag at Maidstone (_ante_, p. 173), so closely resemble the trunk of this plant, that they have been named by Mr. König,[170] _Dracæna Benstedi_; the specimens are in the British Museum. Until the internal structure of these fossils has been examined, the correctness of this identification is, however, uncertain: the external resemblance to the stem of the Dracæna consists in the interrupted annular ridges, denoting amplexicaul leaves: no vestiges of the foliage have been observed.

[170] Petrifactions, p. 49.

[Sidenote: FRESH-WATER PLANTS. FOSSIL CHARÆ.]

Fossil Fresh-water Plants.--The tertiary fresh-water strata often contain abundance of the remains of the aquatic vegetables that inhabited the lakes and rivers in which those deposits were formed. The remains of several species of the common lacustrine plant, the _Chara_, are found in immense quantities in the fresh-water limestones and marls of the Isle of Wight, of the coast of Hampshire, and of the Paris Basin. The shell-marls, still in progress of formation in the lakes of Scotland, and the travertine precipitated from thermal springs, in like manner envelop and preserve the leaves and fruits of recent species.

Fossil Fruits of Chara. (_Gyrogonites._) _Lign. 66._--The Chara is a well-known inhabitant of almost every stream and rivulet. The stems are hollow, and composed of tubes filled with a fluid in which green globules circulate; they form beautiful microscopic objects for exhibiting the circulation in vegetables. The fruit consists of very small nuclei, contained in a calcareous pericarp, composed of five spirally twisted plates, that unite at the summit. These seed-vessels, when first discovered in a fossil state, were supposed to be the shells of mollusks, and a genus was formed for their reception with the name of _Gyrogonites_ (_twisted-stones_); a term still employed, though the vegetable nature of these bodies is well known. In _Plate III. fig. 5_, a branch of the common Chara with seeds is represented: and figures of the seed-vessels, of two fossil species are given in _Lign. 66, figs. 1, 2_.

Specimens of the fossil fruits and stems of Charæ, may be collected in abundance in the fresh-water limestone at East Cliff Bay, Isle of Wight.[171]

[171] See my Geology of the Isle of Wight, _Lign. 5_, p. 109.

_Eocene, Paris._

Fig. 1.--Seed-vessel of _Chara helicteres_ × 10; side view.
1_a_.--View of the base of the same.
1_b_.--One of the spiral valves separated.
1_c_.--View from above.
2.--Seed-vessel of _Chara medicaginula_ × 10. The upper
figure is a side view: the lower, a view of the base.
3.--_Carpolithes ovulum_, magnified side view.
3_a_.--The same, natural size.
3_b_.--Magnified view of the base of the same.
4.--A piece of fresh-water limestone, with impressions
of two stems of _Nymphea arethusa_ ×.
]

The _Purbeck beds_ at Durlstone Bay, near Swanage, also contain numerous Gyrogonites associated with fresh-water shells. The bands of siliceous sinter, which occur in the lowermost deposits, are especially rich in these remains.[172]

[172] I am indebted to the Rev. Osmond Fisher, of Dorchester, for a fine suite of these and other interesting fossils from the Purbeck beds of Ridgway and Osmington, near Weymouth; and to William Shipp, Esq., of Blandford, and Edward Woodhouse, Esq., of Ansty, for many specimens from Durlstone Bay, and Ridgway.

_Fossil Nympheæ._ _Lign. 66, fig. 4._--Those magnificent aquatic plants, the Water-Lilies (_Nympheæ_), that adorn our rivers and lakes with flowers and foliage which partake more of the characters of an exotic flora than any other of our indigenous plants, are also found fossil in the lacustrine marls and limestones of the tertiary formations of France; but the nature of these remains could only be recognized by a profound botanist, for they consist of impressions of the internal structure of the stems, which, however, is so peculiar, that no reasonable doubt of their origin can be entertained. Two imprints on a piece of limestone from Lonjumeau, presented to me by the late M. Alex. Brongniart, are figured in _Lign. 66, fig. 4_; some minute seed-vessels (_Lign. 66, fig. 3_), found with them, closely resemble those of _Nympheæ_, and are supposed to belong to the same plants (_Class. Vég. Foss._ p. 72).

Fossil Flowers.--The tertiary limestones of Monte Bolca (_Wond._ p. 565), so rich in ichthyolites, and other fossil remains of great interest, contain leaves, and even flowers, of liliaceous plants. The specimen figured (_Lign. 67, fig. 3_) is in the Museum at Paris, and described by M. Brongniart under the name of _Antholithes_ (stone-flower) _liliaceus_; it consists of the corolla and calyx: the anthers and pistils have not been observed in any example. The discovery of this fossil should excite the young collector to search diligently for such objects in the tertiary strata of England.

[Sidenote: FOSSIL ANGIOSPERMS.]

Fossil Angiosperms.--The fossil remains of the class which constitutes the grand features of the existing floras of most countries, the _Exogenous Angiosperms_, are now to be considered; and though our survey of fossil botany has partaken but little of a geological arrangement, yet the reader may have observed, that a large proportion of the vegetables composing the floras of the ancient secondary formations, belonged to the Cryptogamous and Gymnospermous classes. A striking contrast is presented in the geological position of the mineralized dicotyledonous plants, of existing genera. These abound in the tertiary strata, and generally in an inverse ratio to the antiquity of the deposit, while their remains are almost wholly absent in the older rocks; neither have there been discovered in the Tertiary, any beds of vascular cryptogamia, at all approaching the immense accumulations in the Carboniferous formations.

Fig. 1.--Thalictroides Parisensis; Tertiary strata, Paris.
2.--Thalictroides Websteri. Isle of Wight.
3.--Antholithes liliaceus. Monte Bolca.
4.--Juglans nux-taurinensis: fossil Walnut, Turin.
4_a_.---Portion of the husk of the shell.
4_b_.--The kernel, formed of calcareous spar.
]

The most remarkable exception, is the single instance of a large leaf of a dicotyledonous plant in the Trias, or New Red sandstone, near Liverpool, described by Sir Roderick Murchison, which much resembles the foliage of a thick-ribbed Cabbage.[FQ]

[173] This fossil is named _Dictyophyllum crassinervium_, by Dr. Lindley, Foss. Flor. pl. cci. and is figured, Sil. Syst. p. 43.

It would be impossible, within the limits necessarily assigned to these volumes, to offer even a general view of the fossil remains of this grand class of vegetables; our remarks must be limited to a few interesting examples and localities.

When stems of dicotyledonous trees only are found, but little certainty can be obtained as to the family to which they belonged; the foliage of many well-known genera offer more positive characters; the flowers are rarely in a state of preservation to afford any valuable data; but the fruits, or seed-vessels, are frequently well preserved, and these may enable the botanist to arrive at precise determinations as to generic, and, perhaps, specific relations.

The tertiary marls of Aix, in Provence, which abound in insects, crustaceans, and lacustrine shells, contain many kinds of dicotyledonous leaves, associated with those of palms. (_Wond._ p. 260.)

The Lignite, or Brown-coal deposits, are almost entirely composed of dicotyledonous trees, belonging to many genera, which are inhabitants of Europe; namely, the Poplar, Willow, Elm, Chestnut, Walnut, Sycamore, Maple, Linden, Buckthorn, Vine, &c. (_Bd._ vol. i. pp. 508-514.)

The beds of brown coal, on the banks of the Rhine, are literally carbonized submerged forests, which in some remote period were drifted from the interior of the Continent into a vast lake or gulf; for the trees bear evident marks of transport, and are destitute of roots and branches. These masses resemble the rafts of forest trees, which are daily floated down the Mississippi into the Atlantic, where they become engulfed in the profound depths of the ocean, and probably will be converted into coal or lignite; and in future ages, may be elevated above the waters, become dry land, and present to the then existing communities of mankind an inexhaustible supply of mineral fuel, composed of species and genera of plants, which possibly may then be extinct, and replaced by peculiar types of vegetation.

Fossil Flora of Œningen. (_Bd._ pp. 511-514).--The celebrated lacustrine tertiary formation of Œningen, whose fossil reptiles and mammalia we shall have to notice hereafter, contains a rich assemblage of dicotyledonous and gymnospermous ligneous vegetables, with a few ferns and grasses. Not only branches and leaves of a species of Vine[174] occur, but even the fruit; fossil grapes being found in these deposits;[175] there are also many aquatic plants. A descriptive list of these fossils, by Professor Braun, of Carlsruhe, is given by Dr. Buckland. The brown-coal of this basin is in thin beds of but little economical importance, but so rich in the vegetation of the miocene tertiary period, that a few days spent in collecting those treasures will amply reward the intelligent tourist who may visit Constance. (See _Wond._ p. 263.)

[174] See Knorr, Mon. des Catastrophes, pl. xxxviii. tom. i.

[175] Fossil grapes from the lignite of Œningen were exhibited by Dr. Daubeny at a late meeting of the Geological Society.

[Sidenote: FOSSIL DICOTYLEDONOUS LEAVES.]

The foliage of dicotyledonous trees frequently occurs in the Eocene marls and limestones, and in some localities in considerable abundance, and in beautiful preservation. Near Bournemouth, on the Hampshire coast, the leaves of many species are met with in a bed of sandy marl, between three and four feet thick: the vegetable substance is carbonized; some of the leaves are referable to the _Lauraceæ_ and _Amentaceæ_, others to the _Characeæ_;[176] a similar deposit of tertiary plants has been discovered near Wareham. These beds belong to the lower group of the Hampshire Basin.[177]

[176] Geol. Proc. vol. iii. p. 592.

[177] As the seed-vessels and other vegetable remains in the Isle of Sheppey are all of a tropical character, while those found in the Eocene strata of Alum Bay, Bournemouth, and Newhaven, are of a temperate climate, as Nerium, Platanus, &c., Prof. E. Forbes infers that the former were transported from distant lands by currents, and that the latter belong to the true flora of the country inhabited by the Palæotheria and other associated mammalia.

_Tertiary. Stradella, near Pavia._

Fig. 1.--Leaf of Poplar (_Populus græca_).

2.--------- Maple (_Acer_).

3.--------- Water-spike (_Potamogeton_).

4.--------- Willow (_Salix_).

5.--------- Chestnut (_Æsculvs_).
]

The red marlstone associated with lignite in the plastic clay beds at Castle Hill, Newhaven (_Geol. S. E._ p. 54), contains leaves of a similar kind; a seed-vessel of a coniferous tree has also been found in it.

Some of the most interesting examples of dicotyledonous leaves that have come under my notice, are from the Sub-Apennine tertiary strata, at Stradella, near Pavia. They belong to several genera of arborescent, or at least ligneous plants, and most of them to species which still grow in Italy. In some examples the substance of the leaves is changed into carbon, and the structure well preserved; but, in general, sharp imprints on the stone are the only traces of the originals. They are found in a gypseous marl, of a cream colour; and, from their perfect state, it is inferred that they were enveloped in the soft matrix immediately after their fall, and preserved by the rapid crystallization of the gypsum. Two specimens from my cabinet are figured in _Plate III._ _figs._ 4 and 8; and outlines of a few other examples, in _Lign. 68_.

Carpolithes (_Fossil Fruits_).--In the description of the fossil fruits from the Isle of Sheppey, several kinds of dicotyledons were included. Many species also abound in the lignites of Germany, France, and Italy; in those near Frankfort, seed-vessels of the Maple, Elm, Hornbeam, Birch, Willow, and Walnut, &c. In the environs of Turin, fruits of a species of Walnut (_Juglans_, _Lign. 67_), occur in the newer tertiary deposits, and are called Turin-nuts; the ligneous envelope has perished, but the form of its surface, and of the inclosed kernel, is preserved in calcareous spar. These nuts differ, both in the pericarp and kernel, from the living species: the lobes are simple (_Lign. 67, fig. 4^b_), and not subdivided as in the common walnut; a species has been discovered at Lons-le-Saulnier, in which the lobes are mamillated.

Two kinds of fruits belonging to plants of the order _Ranunculaceæ_, and related to _Thalictrum_ (_Meadow-rue_), have been found in the eocene deposits of France and England; one in the Paris basin, (_meulière du terrain d'eau douce supérieur_,) by M. Alexandre Brongniart, and the other in the Isle of Wight, by Mr. Webster. In the specimen from the last-named locality the pericarp is carbonized, and its cavity filled with clay. Figures of these seed-vessels are given in _Lign. 67, figs. 1, 2_.

Carpolithes Smithiæ.--I would notice in this place some very remarkable fossil fruits that are occasionally met with in the White Chalk of Sussex and Kent, and appear to belong to dicotyledonous trees. The first specimen was discovered by me in a chalk-pit near Lewes, and is described in my "Fossils of the South Downs:" some illustrative examples collected by Mrs Smith, of Tunbridge Wells, tending to elucidate the nature of the original more satisfactorily than those in my collection, are figured and described by me in the Journal of the Geological Society, 1843, under the above name. These fruits are of an oval form, about one and a half inch long, and one inch wide, and are pressed almost flat. They are of a rich burnt-sienna colour, mottled with white, from the chalk having permeated their substance, and are studded over with slight eminences, which are the exposed summits of oblong flattened seeds. Although the internal structure is not preserved, there can be no doubt that the originals were spurious compound berries, having, like the Mulberry, the seeds imbedded in a soft pulpy mass.

[Sidenote: FOSSIL DICOTYLEDONOUS TREES.]

Fossil Dicotyledonous Trees.--The occurrence of trunks and branches of angiospermous trees in a carbonized state has already been described; like the monocotyledons and conifers, they also occur silicified.

The most beautiful specimens I have seen are from the Lybian and Egyptian deserts, and were collected by my friend, the late Colonel Head. In these the most delicate vascular tissue is permeated by chalcedony and jasper, and the vessels are filled with silex of a bright vermilion and blue colour, while the cellular structure is of a rich yellow. Fragments of these fossil trees are scattered everywhere among the sands of the desert; the most interesting locality is an irregular plateau, which reposes on marine limestone, considerably above the level of the Nile, about seven miles east by south from Cairo. This district is called the _petrified forest_, from the immense quantities of silicified trees with which it is covered. It is thus graphically described by a late traveller:--

"Having passed the tombs of the Caliphs, just beyond the gates of Cairo, we proceed to the southward nearly at right angles to the road, across the Desert to Suez: and after travelling some ten miles up a low barren valley covered with sand, gravel, and sea-shells, fresh as if the tide had retired but yesterday, we cross a low range of sand-hills, which has for some distance run parallel to our path. The scene now presented is beyond conception singular and desolate. Heaps of fragments of large trees converted into stone everywhere meet the eye, and when struck by our horses' hoofs rang like cast iron; they extend for miles in the form of a decayed and prostrate forest; and the appearance is so natural, that were it in Scotland or Ireland, it would pass without remark as a drained bog, on which the exhumed trees lay rotting in the sun. The roots, and rudiments of the branches, are in many cases nearly perfect, and in some the worm-holes eaten under the bark are distinctly recognizable."[178]

[178] Bombay Times.

Many of the trunks are scattered over the surface, among rolled and angular fragments of dark grit, and pebbles of jasper,[179] chert, and quartz. The large trunks occur in great numbers on dark-coloured knolls, where they lie, like the broken stems of a prostrate forest, crossing each other at various angles. Two of the largest measured respectively forty-eight, and sixty feet in length, and two and a half, and three feet in diameter, at the base. With but two or three exceptions, all the specimens examined microscopically, are dicotyledons. No traces of seed-vessels or leaves have been detected.

[179] The jaspers are known to lapidaries as _Egyptian Pebbles_.

The situation and condition of these petrified forests, indicate great changes in the relative position of the land and sea in that part of Egypt; for the trees must have grown on the dry land formed by the elevated bottom of a former ocean; which must have subsided, and been covered by beds of sand and pebbles; another elevatory movement must have raised the entire series of deposits to their present situation, and the retiring waters have removed the loose portions of the last formed strata, and dispersed them, with fragments of the silicified trees, over the surface of the Egyptian and Lybian deserts.[180]

[180] See a Memoir on the Geology of Egypt, Geol. Proc. vol. iii. p. 782; and on the Petrified Forest near Cairo, vol. iv. p. 349, by Lieut. Newbold, F.R.S.

[Sidenote: DICOTYLEDONOUS OF THE CRETACEOUS EPOCH.]

Dicotyledons of the Cretaceous Epoch.--Among the crowd of interesting facts relating to the botanical character of the earlier periods of geology which recent observations have brought to light, one discovery demands especial notice, and I have reserved it for this place, rather than introduce it in an earlier section.

In the neighbourhood of Aix-la-Chapelle the lower members of the Cretaceous formation, viz. the Greensand, Galt, and Chalk-marl, are well developed, and comprise a series of littoral deposits of the great Chalk ocean that extended westwardly between France and England, on both sides of the existing Channel, and eastwardly over North and Central Germany, Sweden, Poland, and Russia, far into Asia. The series of strata at Aix-la-Chapelle is several hundred feet in thickness, and the lowermost beds lie immediately on the Carboniferous rocks of the country.

Dr. M. H. Debey,[181] to whose scientific labours we are indebted for an accurate knowledge of these interesting facts, divides these cretaceous deposits into four groups, the lowermost of which appears to be the equivalent of our Greensand; it consists of beds of clay and sand, the middle portion abounding in stems, leaves, and fruit, and the resin of coniferous trees.

[181] See Geol. Journal, vol. vii. p. 109.

The epidermis of the leaves often occurs in a carbonized state, and is recognizable by its microscopic structure. Xylophagous mollusks are found in the petrified and carbonized wood. Fresh-water Desmidiaceæ, and a few marine remains, are associated with this fossil flora, which is distinguished by the abundance of Ferns and dicotyledonous leaves, and the scarcity of Cycads; among them are undoubted _Proteaceæ_.

The specimens collected by M. Debey from the lower cretaceous beds are the following:

Algæ, 15. Filices, 28. Hydropteridæ, 2. Cycadeæ, 5. Naiadeæ, 5. Palmæ, 1. Coniferæ, 20. Julifloræ, 5. Credneriæ, 3. Leaves of Dicotyledons, undetermined, 26. Fruits undetermined, 8. Woods.[182]

[182] Geol. Journal, vol. vii. p. 111.

This assemblage of angiosperms, with gymnosperms, and cryptogamia, at the commencement of the Cretaceous epoch, when the Iguanodon and other reptilian forms of the Oolite and Wealden still inhabited the land and water, proves, as Sir Charles Lyell has remarked,[183] that the meteorological phenomena of that remote period differed in no essential particular from those which now prevail.

[183] Supplement to the New Edition of Elements of Geology, 1852, p. XV.

* * * * *

RETROSPECT OF FOSSIL BOTANY.

[Sidenote: RETROSPECT OF FOSSIL BOTANY.]

If we pass from the consideration of details of structure, and of botanical affinities, to a general survey of the mineralized remains of the vegetable kingdom, we perceive that from the palæozoic deposits, to those which are contemporaneous with the human race,--from the coal-measures to the peat-bogs of modern times,--vast accumulations of vegetable matter, in various states of carbonization, have been produced from the imbedded relics of the terrestrial floras that flourished during the respective periods of their formation; petrifaction, or the transmutation of vegetable tissues into stone, from the infiltration of siliceous, calcareous, or metallic solutions, being an accidental process, dependent on the physical conditions under which the trees and plants were submerged, and entombed in the strata.

Although the entire system of vegetable life which prevailed during the earlier ages of the world is but partially revealed by the fossil remains which geological researches have brought under the examination of the naturalist,--for numerous tribes of plants may have existed of which no traces have been detected, while of species of delicate tissues all vestiges may have perished,--yet a review of the facts hitherto obtained, presents some highly important and unexpected results, as to the characters of the successive floras which prevailed during the palæozoic, secondary, and tertiary epochs. And though deductions of this nature must, in the present state of our knowledge, be regarded in the light of shifting hypotheses to be modified or abandoned with the progress of discovery,--yet the predominating types which characterize the flora of one system of formations, differ so essentially from those of another, that it may be reasonably inferred such apparent distinctions are the effect of organic laws, and not illusions arising from our misinterpretation of the natural records of former conditions of the vegetable world.

The absence in the most ancient deposits of the entire class of Angiosperms, or flowering plants, which constitutes the leading features of the floras with which we are familiar,--the abundance of unknown types of Cryptogamia, and the extinction or disappearance of those tribes in the succeeding formations, and the prevalence of new species and genera belonging to another class;--the predominance in one flora, both in number and variety, of certain tribes, and their decadence in the next period; while a family subordinate in the antecedent epoch, and known but by a small number of species, suddenly acquires a pre-eminence both in numbers and variety;--are phenomena, which the facts brought before us in the course of this argument, present in a striking point of view.

Assuming these data as the basis of a philosophical generalization, M. Brongniart arranges the known species of fossil plants into three grand systems, which correspond with the great geological periods, comprehended in the palæozoic, secondary, and tertiary formations.

The first or most ancient flora is characterized by the predominance of _Cryptogamic Acrogens_--the _Ferns_ and _Club-mosses_; the second by the large development of the _Dicotyledonous Gymnosperms_--the _Cycads_ and _Conifers_: the third by the appearance and prevalence of the _Angiosperms_, both dicotyledonous and monocotyledonous. The following table presents a concise view of the results of M. Brongniart's investigation.[184]

[184] For details, and a masterly review of the subject, the original Memoir must be consulted. See Tableau des Genres de Végétaux Fossiles, considérés sur le point de vue de leur Classification Botanique et de leur Distribution Géologique, par M. Adolphe Brongniart. Paris, 1849.

CHARACTER OF THE FLORAS. GEOLOGICAL EPOCHS.

I. Règne des Acrogènes; the Flora } The _Devonian_, _Carboniferous_,
of Vascular Cryptogamia. } and _Permian_, Formations.

II. Règne des Gymnospermes; the } The _Triassic_, _Jurassic_ (or
Flora of Cycadaceæ and Coniferæ. } _Lias_ and _Oolite_), and
} _Wealden_, Formations.

III. Règne des Angiospermes. } The _Cretaceous_, and _Tertiary_
Flora of Dicotyledonous and } (_Eocene_, _Miocene_, and
Monocotyledonous flowering } _Pliocene_), Formations.
plants, or Angiosperms. }

It must be observed that this table is only designed to indicate the successive _predominance_ of each of the three classes of the vegetable kingdom, in the respective epochs, and not the entire exclusion of the others. Thus, in the two first, both Acrogens and Gymnosperms existed; but in the first period the former greatly exceeded the latter, both in number and magnitude; while in the next the Gymnosperms acquired the ascendancy; but in both these epochs, from the Devonian to the Wealden inclusive, very few if any Angiosperms, or flowering dicotyledons, existed. With the Cretaceous period the Angiosperms appear in great numbers, and in the Tertiary epochs acquire the importance they possess in the existing floras.

The following analysis of the flora of the Carboniferous epoch, by M. Brongniart, will exemplify these remarks.[185]

[185] See Wonders of Geology, vol. ii. pp. 726-733, for an account of the Carboniferous floras and deposits.

ANALYSIS OF THE CARBONIFEROUS FLORA

Cryptogamia (_Amphigens_). Algæ 4
Champignons 6
--- 6
(_Acrogens_). Ferns 250
Lycopodiaceæ (Club-mosses) 83
Equisetaceæ 13
--- 346
Dicotyledonous Gymnosperms. Asterophyllites 44
Sigillariæ 60
Nœggerathiæ 12
Cycadeæ? 3
Coniferæ 16
--- 135
_Dicotyledonous Angiosperms_ 0
_Monocotyledons?_ (very doubtful) 15
---
502
---

Thus out of five hundred species, 352 are Cryptogamia; and with the exception of six, belong to the Acrogens.[186]

[186] Bronn gives the annexed numerical summary of the fossil and recent species of plants:--

_Plants._--Cellular 188 Fossil. 9,100 Living.
Vascular 1,867 60,303
----- ------
2,055 69,403 (80,000, Lindley.)
----- ------

In conclusion, I must direct attention to a remarkable character of the palæozoic and secondary floras, namely, the almost entire absence of the _Gramineæ_ or Grasses, which constitute so large a proportion of the existing vegetation.

Above six hundred species of plants have been discovered in the British strata;[187] and yet two species of _Poa_ (a tribe of grasses), from Coalbrook Dale, are the only known examples of Gramineæ. It has been suggested that the greater or lesser durability of the foliage of certain vegetables, may have occasioned their presence or absence in the carboniferous deposits, and experiments were instituted by Dr. Lindley with the view of determining this question. But though it was found that, when the foliage of various families was subjected to long maceration, the leaves of dicotyledons and grasses disappeared, while those of ferns and cycads remained, this fact does not meet the exigencies of the case, for we have no evidence to show that the fossil leaves were ever placed in similar conditions; on the contrary, there is reason to conclude that they were imbedded under circumstances that arrested the usual progress of decomposition, prevented the escape of the hydrogen and other gaseous elements, and gave rise to the bituminous fermentation by which they were converted into lignite and coal; and we have no proof that, had grasses been associated with the ferns, they would not have undergone a similar change. Moreover, there are countries in which the ferns now assume the numerical proportion of the grasses of other latitudes; for example. New Zealand, which also presents in its fauna a striking analogy to that of the carboniferous deposits, in the almost entire absence of indigenous mammalia; one species of Rat being the only known living quadruped.

[187] See Mr. Morris's Catalogue of British Fossils.

On this subject Dr. Dieffenbach remarks, that "although in its flora New Zealand has some relationship with the two large continents between which it is situated, America and Australia, and even possesses some species identical with those of Europe, without the Latter being referable to an introduction by Europeans, yet the greater number of species, and even genera, are peculiar to it. New Zealand, with the adjacent islands, Chatham, Auckland, and Macquarrie, forms a botanical centre. It is sufficiently distant from both continents to preserve its botanical peculiarities, and it offers the most striking instance of an acknowledged fact in all branches of natural history, viz. that the different regions of the globe are endowed with peculiar forms of animal and vegetable life. The number of species of plants at present known is 632, of which 314 are dicotyledonous, and the rest, or 318, are monocotyledonous and cellular. The monocotyledons are few in comparison with the cellular plants, for there are but seventy-six species. The grasses have given way to ferns, for the ferns and fern-like plants are by far the most abundant in New Zealand, and cover immense districts. They _replace the Gramineæ_ of other countries, and give a character to all the open land of the hills and plains. Some of the arborescent kinds grow to thirty feet and more in height, and the variety and elegance of their forms, from the minutest species to the most gigantic, are very remarkable."[188] In the accumulations of vegetable matter now in the progress of formation in the morasses, bays, and creeks of New Zealand, the remains of ferns largely predominate; and I am informed by my son,[189] that in the estuaries they are associated with numerous shells of brachiopodous mollusca.

[188] Dr. Dieffenbach's New Zealand.

[189] Mr. Walter Mantell, of Wellington, New Zealand.

* * * * *

ON COLLECTING BRITISH FOSSIL VEGETABLES.

[Sidenote: ON COLLECTING FOSSIL VEGETABLES.]

From what has been advanced, the student will perceive that to obtain an illustrative collection of the fossil plants of Great Britain, many different localities must be visited.

The fruits and stems of Palms, Conifers, and many dicotyledons, may be collected in the Isle of Sheppey, and other places where the London Clay is exposed. (See _Excursion to the Isle of Sheppey_, Part IV.) Cycadeous stems and coniferous wood may be procured in the Isle of Portland; from the Wealden Cliffs along the southern shore of the Isle of Wight; and on the Sussex coast, from Bexhill, by St. Leonard's, to the east of Hastings. The foliage of several species of Zamiæ and ferns, occur abundantly in the lower Oolite, along the Yorkshire coast, near Scarborough, and at Gristhorpe Bay. The Lias of Lyme Regis, Charmouth, and their vicinity, affords stems and branches of coniferous trees, and leaves of cycads.

Ferns, Sigillariæ, Calamites, and the usual plants of the carboniferous flora, may be found in every coal-mine; and the Devonian limestones of the South of Ireland yield ferns and Lepidodendra. In Forfarshire the lower Devonian shales abound in the foliage of aquatic, apparently fluviatile, plants.[190]

[190] See Memoir on the Telerpeton; Geol. Journ. vol. viii. p. 106.

A list of some of the most productive British localities is subjoined.

In addition to the suggestions already given as to the mode of collecting specimens, it may be necessary to state that the leaves in the tertiary marls and clays are generally very delicate and friable, and liable to flake off in the state of a carbonaceous film. This may, in a great measure, be prevented by carefully covering them with a thin coating either of mastic varnish, or gum-water, before they are placed in the cabinet. In extracting these specimens, a broad chisel will be found the most convenient instrument. In searching for fossils in coal-mines, the collector should remember that the ironstone nodules often contain beautiful examples of the leaves of ferns, and fruits of Lepidodendra. These nodules, when of an oblong shape, should be split open in a longitudinal direction, by a smart blow of a hammer, and the inclosed leaf will thus be exposed, as shown in _Lign. 3, figs. 2, 3_, _ante_, p. 69.

* * * * *

BRITISH LOCALITIES OF FOSSIL VEGETABLES.

[Sidenote: BRITISH LOCALITIES OF FOSSIL VEGETABLES.]

Allenbank, Berwickshire _Carb._ Stems of Conifers, &c.

Alum Bay, Isle of Wight _Tert._ { Fruit, dicotyledonous leaves,
{ lignite; Charge, stems and
{ seed-vessels.

Ashby-de-la-Zouch, } _Carb._ { Coal plants in great abundance.
Leicestershire }

Bignor, Sussex } _Cret._ } Fucoids.
} _Firestone_ }

Binstead Quarries, near } _Tert._ { Charæ, stems and seed-vessels.
Ryde, Isle of Wight }

Blackdown, Devonshire _Gr. Sand._ Silicified wood--coniferous.

Bognor, Sussex _Tert._ { Coniferous and monocotyledonous
{ wood; washed
{ up on the shore.

Bolton, Lancashire _Carb._ Lepidodendra, Sigillariæ, &c.

Bournemouth, Hants _Tert._ { Dicotyledonous leaves.[191]

[191] Fruits and Fern-leaves have been collected here by Mr. Beckles and stems of a species of _Arundo_, by Mr. Alfred Woodhouse.

Brook-point, Isle of Wight _Wealden_ { Cycads, and coniferous
{ wood.

Burdie House, near Edinburgh _Carb._ Ferns, wood, &c.

Calbourn, Isle of Wight _Tert._ Charæ, stems and fruits.

Camerton, near Bath _Carb._ Usual plants of the coal.

Charmouth, Dorset _Oolite_ { Coniferous wood; Cycads;
{ fruit of Pandanus.

Clifton, near Manchester _Carb._ { Coal plants in great
{ perfection.

Coalbrook Dale, Shropshire _Carb._ { Usual plants of the coal, in
{ abundance. The ironstone
{ nodules are rich in
{ fern-leaves, fruits of
{ lepidodendrons, &c.

Cuckfield, Sussex _Wealden_ { Clathraria, Endogenites,
{ Ferns, and Lignite.

Durlstone Bay, near Swanage _Wealden_ { Charæ; Gyrogonites in
{ abundance.

Folkstone, Kent _Galt_ { Coniferous wood--bituminous,
{ and pyritified.

Glasgow _Carb._ { Coal plants, and large trunks
{ of Coniferæ.

Hastings, Sussex _Wealden_ { Clathrariæ, Cycads,
{ Endogenites, Ferns, Thuites,
{ &c.

Herne Bay, Kent { _London { Fruits of Conifers, and
{ Clay_ { Palms: wood.

Kilkenny, Ireland _Carb._ Calamites, ferns, &c.

Knocktopher, nr. Kilkenny, } _Devonian_ } Ferns, Lepidodendrons, &c.
Ireland } }

Leeds _Carb._ { Beautiful coal-plants from
{ the pits in the vicinity.

Liverpool _New Red_ Fuci.

Lyme Regis, Dorset _Lias_ Cycads; Conifers; wood.

Maidstone, Kent _Greensand_ { Fruits and wood of Abies,
{ Pinus, Dracæna; Fuci.

Malton _Oolite_ Fruits, and Cycads.

Newcastle (Jarrow Colliery) _Carb._ { Coal plants in great
{ variety.[192]

[192] In collecting _Stigmariæ_, the student should particularly attend to the relation existing between these fossils and their supposed stems; for it is probable that roots of this type will be found to belong to other genera, besides Sigillaria, and Lepidodendron (_ante_, p. 136).

Newhaven (Castle Hill), } _Tert._ { Dicotyledonous leaves and
Sussex { fruit--_rarely_.

Portishead (on the shore) } _Millstone } Sigillariæ, Stigmariæ, &c.
} Grit_ }

Portland, Isle of _Wealden_ { Petrified forest of Conifers,
{ with Cycads.

Pounceford, Sussex _Wealden_ Equiseta, Ferns, Lignite.

Runswick, Yorkshire Coast { _Lower } Cycads, Ferns, &c.
{ Oolite_ }

Saltwick, near Whitby { _Lower } Foliage of Cycads, Ferns, &c.
{ Oolite_ }

Sandown Bay, Isle of Wight _Wealden_ Conifers, Cycads, wood.

Scarborough _Oolite_ Ferns, Cycads, Equiseta, &c.

Selmeston, Sussex { _Greensand_ } Coniferous wood.

Sheppey, Isle of { _London { Fruits innumerable, wood,
{ Clay_ { &c. (_ante_, p. 186.)

Stonesfield, Oxfordshire _Oolite_ Fuci, Cycads, Thuites, &c.

Swindon, Wilts _Oolite_ Coniferous wood, & Cycads.

Tunbridge Wells (vicinity) _Wealden_ Ferns, several species.

Ventnor, Isle of Wight _Firestone_ Clathraria, Conifers.

Wareham, Dorset _Tert._ { Dicotyledonous foliage, and
{ Palm-leaves.

Whitecliff Bay, I. of Wight _Tert._ Palm-leaves, Charæ, &c.

Whitwick, Leicestershire _Carb._ The usual coal-plants.

The above list must, of course, be considered as merely suggestive: many other localities are mentioned in the previous notices of the fossil genera.