  FOSSIL VEGETABLES. In the present section of this work, I propose to explain the botanical arrangement and nomenclature of fossil plants; and figure and describe one or more species of the genera that are most likely to come under the observation of the student, either in public or private collections, or in the course of his researches in the field. To determine the botanical relations of fossil leaves and stems, reference must be had to works expressly devoted to the subject; namely, the "British Fossil Flora," by Dr. Lindley and Mr. Hutton, and the "Histoire des VÉgÉtaux Fossiles," by M. Adolphe Brongniart. The classification of the last-named eminent botanist is here adopted, as the most easy of application. With regard to the nomenclature, it may be necessary to remark, that when a fossil plant undoubtedly belongs to a recent genus, the usual botanical name is employed: for example, Equisetum Lyellii; when the fossil does not possess all the generic characters, yet is evidently allied to a recent genus, the term ites (from ?????, lithos, stone), is added—as Equisetites, Palmacites, &c.; and this termination is invariably adopted by some authors. When the fossil plant differs altogether from any known type, it is distinguished by some arbitrary generic name, as Bucklandia, Sigillaria, &c. There are also a few provisional genera for the reception FOSSIL CRYPTOGAMIA. The following account of the principal types of the ancient floras whose relics are preserved in the mineral kingdom, though commencing with those of the most simple structure, the Cryptogamia, and advancing to the higher orders, is not strictly botanical; for it was found convenient, in some instances, to notice certain species and genera of different orders under the same head, from their occurrence in the same geological formations. It is estimated that not more than two thousand species of plants have been discovered in a fossil state, while the known recent species amount to upwards of eighty thousand. Cellular Cryptogamia; AlgÆ.—The plants designated by botanists AlgÆ, and commonly known as sea-weeds, lavers, and fresh-water mosses, are of the most simple structure—mere aggregations of cells—but present innumerable varieties of form and magnitude: many species are mere vesicles of such minuteness as to be invisible to the unassisted eye, except accumulated in countless myriads, when they appear as a green, purple, or reddish, slime in the water; or as a film on wood or stone, or on the ground, in damp situations; while others are tough branched marine plants, many fathoms in length. The AlgÆ form three principal groups: 1. the jointless, as the Fuci, the Dulses, Tangles, and Lavers: 2. the jointed, which are composed of thread-like articulated tubes; such are the fresh-water ConfervÆ: 3. the disjointed, or Brittle-worts, so called from their spontaneous self-division, which is in some kinds complete, in others only partial; and these, As many of these forms are endowed with spontaneous motion, and possess other properties common to animal organization, it is not surprising that their vegetable nature was doubted, and that even so profound a naturalist as M. Ehrenberg placed them in the animal kingdom: the greater number being comprised in his family of BacillariÆ, were described in the former edition of this work, as Infusoria or Animalcules; in conformity with the classification of the illustrious microscopist, whose splendid works and indefatigable labours have so greatly promoted the advancement of microscopical investigation. FOSSIL DIATOMACEÆ. These minute vegetable organisms are placed by botanists in two tribes, the DiatomaceÆ or the Brittle-worts, and the DesmidieÆ. The latter are exclusively inhabitants of fresh-water, while a large proportion of the former are marine plants. Some naturalists (M. BrÉbisson) restrict the name DiatomaceÆ to those species which secrete siliceous envelopes; and that of DesmidieÆ to those whose structures are not siliceous, and are reducible by heat to carbon. As the durable parts of these plants alone concern the geologist, the name DiatomaceÆ will be employed as a general term in reference to their fossil remains. These tribes of AlgÆ abound in every lake and stream of fresh-water, in every pool or bay, and throughout the ocean from the equator to the poles. Certain kinds of sea-weeds secrete carbonate of lime; but the DiatomaceÆ have the power of separating silex, or the earth of flint, from the The extent of this infinitesimal flora throughout regions where no other forms of vegetation are known, is strikingly demonstrated by the observations of our eminent botanical traveller. Dr. Joseph Hooker, in his account of the Antarctic regions. "Everywhere," Dr. Hooker states, "the waters and the ice alike abound in these microscopic vegetables. Though too small to be visible to the unassisted eye, their aggregated masses stained the iceberg and pack-ice wherever the latter were washed by the sea, and imparted a pale ochreous colour to the ice. From the south of the belt of ice which encircles the globe, to the highest latitudes reached by man, this vegetation is everywhere conspicuous, from the contrast between its colour and that of the white snow and ice in which it is imbedded. "In the 80° of south latitude all the surface ice carried along by currents, and the sides of every berg, and the "The universal existence of such an invisible vegetation as that of the Antarctic Ocean is a truly wonderful fact, and the more so from its being unaccompanied by plants of a high order. This ocean swarms with mollusca, and entomostracous crustaceans, small whales, and porpoises; and the sea with penguins and seals, and the air with birds; the animal kingdom is everywhere present, the larger creatures preying on the smaller, and these again on those more minute; all living nature seems to be carnivorous. This microscopic vegetation is the sole nutrition of the herbivorous animals; and it may likewise serve to purify the atmosphere, and thus execute in the Antarctic latitudes the office of the trees and grasses of the temperate regions, and the broad foliage of the palms of the tropics." Dr. Hooker also remarks that the siliceous envelopes of the same kinds of diatomaceÆ now living in the waters of the South Polar Ocean, have contributed in past ages to the formation of European strata; for the tripoli and the phonolite stones of the Rhine, contain the siliceous envelopes of identical species. Such are the comments of one of our most distinguished botanists, on the phenomena under review. The reader will perhaps ask, what then are the essential characters which separate the animal from the vegetable kingdom? To this question it is impossible to give a satisfactory reply: perhaps the only distinction that will be generally admitted by zoologists and botanists is the following:—animals require RECENT DIATOMACEÆ. Recent DiatomaceÆ. Plate IV.—To familiarize the reader with the nature of these vegetable organisms, a few recent species are represented in Plate IV., coloured as they appear when alive, under the microscope; the figures are magnified as expressed by the fractions. Xanthidium. Plate IV. figs. 1, 2, 3, 4, 5.—The case or frustule of this genus consists of a hollow, siliceous globe, beset with spines. The increase of the Xanthidia by self-division, produces the double appearance in the figures, all of which are in the progress of separation. Pyxidiculum. Plate IV. fig. 2.—The case is a little saucer-shaped box, and is invested by a membrane. Bacillaria. Plate IV. fig. 6.—A simple siliceous frustule, of a prismatic shape, forming a brilliant chain, which often appears in zigzag, in consequence of incomplete self-division. An immense number and variety of forms are placed in this family by Ehrenberg, with a multitude of generic and specific names. The fresh-water species inhabit every pond and lake, and the marine every sea. Fossil species are equally abundant. Cocconeis. Plate IV. fig. 7.—This is a very elegant type; the frustule consists of a simple siliceous case, with a central opening; it never occurs in chains like the former. It has been found fossil near Cassel. Navicula. Plate IV. figs. 8, 9, 14, 15.—The plants of this genus are free, and float in the water apparently by the agency of cilia. Their case is a boat-like envelope with six Galionella. Plate IV. figs. 10, 11.—These algÆ are free, and the frustules of a cylindrical, globular, or discoidal form; they occur in chains, in consequence of the self-division being imperfect, and the new individuals remaining attached to the old. The GalionellÆ are most abundant and prolific, and inhabit every pool, stream, and lake: fossil species occur in the Virginian marls, and other strata. Synhedra. Plate IV. fig. 12.—The frustules are siliceous, and of a slender, elongated form. The plant is attached by the base (fig. 12 a.) in youth, and afterwards becomes free. It is found fossil in the Mountain-meal of Santa Flora, and many other deposits. Podosphenia. Plate IV. fig. 13.—The frustule is cruciform, or wedge-shaped, and attached in youth by the small end, but afterwards becomes free. These plants are often arranged in clusters, as in the figure. M. Ehrenberg states that they inhabit the sea, and not fresh-water; but I have found them in streams communicating with the Thames. PodospheniÆ abound in the polishing slate of Bilin. Eunotia. Plate IV. figs. 16, 17.—The frustule is siliceous, and either simple or bivalve; flat below, and convex, and often richly dentated above. An empty case is shown fig. 16; and a group of living Eunotice attached to a stem of conferva, fig. 17. Several fossil species have been discovered at Santa Flora. That the general reader, whose attention is for the first time directed to this subject, may be prepared for the enormous "This fresh-water plant is seen in immense quantities in the mountain brooks around West Point, the bottoms of which are literally covered in the first warm days of spring with a ferruginous-coloured mucous matter, about a quarter of an inch thick, that, on examination by the microscope, proves to be filled with millions and millions of these exquisitely beautiful siliceous organisms. Every submerged stone, twig, and spear of grass, is enveloped by them; and the waving plume-like appearance of a filamentous body covered in this manner, is often extremely elegant. Alcohol completely dissolves the endochrome (soft colouring matter) of this species, and the frustules are left as colourless as glass, and resist the action of fire." The yellow or ochreous scum observable in ponds, ditches, and stagnant pools, is an aggregation of diatomaceÆ, whose frustules are feriniginous, and of such extreme minuteness, that a billion of their cases would not be more than a cubic inch in bulk. Fossil DiatomaceÆ.—From this notice of a few recent types, we proceed to the investigation of the fossil remains of this tribe of AlgÆ. In peat-bogs and swamps, both of modern and ancient date, masses of a white marly or siliceous paste (hydrate of silica), are often observed, and these are found upon microscopical observation to be wholly made up of the frustules of NaviculÆ, BacillariÆ, GalionellÆ, &c., with an intermixture of the needle-like spicules of fresh-water sponges. Many of the peat-bogs of Ireland contain layers of a white Lign. 4. Siliceous Frustules of DiatomaceÆ, and Spicules of SpongillÆ; from a deposit on the banks of the river Bann, Ireland. (Seen by transmitted light, and highly magnified.) FOSSIL DIATOMACEÆ OF IRELAND. Fossil DiatomaceÆ from Ireland, Lign. 4.—Dr. Drummond describes a bed of this kind near the base of the Mourne Mountains, in the County of Down, Ireland. It consists of a very light white substance, resembling in appearance carbonate of magnesia: it has a coarse and somewhat fibrous fracture, and is easily reduced to powder. It is almost entirely siliceous, and is composed of the cases of diatomaceÆ of the usual fresh-water species, without any admixture of inorganic matter. On the banks of the river Bann, in the same county, there is an extensive stratum of a similar earth, and which, from being in much request for polishing plate, is locally known as Lord Roden's plate powder. This earth is wholly made up of the siliceous frustules of many kinds of this tribe Beds of siliceous marl—that is, of argillaceous earth combined with a large amount of minute particles of silex, all of which prove to be organisms when examined by a high magnifying power,—have been found in numerous places not only in England, but all over the world, since M. Ehrenberg first directed attention to their nature and origin. Near Bryansford (Newcastle), Binstwick in Holderness, and in the Fens of Lincolnshire and Cambridgeshire, extensive fresh-water microphytal deposits have been discovered and examined. From our Antipodes I have received many examples of these vegetable earths. My eldest son, Mr. Walter Mantell, discovered an extensive bed of white marl on the banks of the great brackish-water lake of Waihora, in the middle island of New Zealand, consisting entirely of frustules of BacillariÆ. From New Plymouth he obtained some new and exquisite forms of Navicula, Stauroneis, &c.; ranges of low hillocks of sand, of considerable extent, being made up of microphytes (microscopic plants). Mr. Dean, of Clapham Common, informs me that a Lign. 5. Fossil. GaliomellÆ; highly magnified. In America, recent beds of this kind of great extent have been observed and examined by that distinguished microscopist, Dr. Bailey, Professor of Chemistry in the Military Academy at West Point: and the pages of that excellent scientific periodical, Silliman's American Journal of Science, are enriched with figures and descriptions of the microphytes of which they are mainly composed. But the Tertiary formations contain strata of this nature, which far surpass in the abundance and variety of their organic contents, any of the modern deposits we have noticed. The Polierschiefer, or polishing-slate of Bilin, is stated, by M. Ehrenberg, to form a series of strata fourteen feet in thickness, entirely made up of the siliceous shells of GalionellÆ, of such extreme minuteness, that a cubic inch of the stone contains forty-one thousand millions. The Berghmehl (mountain-meal, or fossil farina), of San Flora, in Tuscany, is one mass of these organisms. In Lapland a similar earth is met with, which, in times of scarcity, is mixed by the inhabitants with the ground bark of trees, for food; some of this earth was found to contain twenty different species of algÆ. In the district of Soos, near Egra, in Bohemia, a fine white infusorial earth occurs, about three feet beneath the surface; this substance, when dried, appears to the naked eve like pure magnesia, but under the microscope is seen to be mainly constituted of elegant disciform cases of a Some beds of porcelain-earth M. Ehrenberg found to be in a great measure made up of concentric articulated rings, entire and in fragments (see FOSSIL DIATOMACEÆ OF VIRGINIA. Lign. 6 Organic Bodies in Porcelain Earth; highly magnified. Fossil DiatomaceÆ of the Richmond-earth; Virginia.—The town of Richmond, in Virginia, is built on strata of siliceous marl of great extent, which earth; highly magnified. have a total thickness, beneath and around the town, of more than twenty feet. These marls, whose organic composition was first detected by Professor W. B. Rogers, are referred by that eminent American geologist, to the older tertiary (eocene, or miocene) formations. They occupy considerable districts, spreading out into sterile tracts along the flanks of the hills, their siliceous character rendering them unfavourable to vegetation. The investigations of Dr. Bailey have shown that the frustules so abundant in this earth, consist of several species of Navicula ( The most remarkable forms are disciform frustules, having their surfaces elaborately ornamented with hexagonal spots disposed in curves, and bearing some resemblance to the engine-turned case of a watch. Lign. 7. Microphytes Tertiary. Virginia.
When a few grains of the marl are prepared, and mounted on a glass, almost all these varieties will be manifest, so largely is this earth composed of organic structures; in fact, very few inorganic particles are intermixed, the merest At Petersburg, in Virginia, a sandy marl occurs, interstratified with deposits which, from their shells, are referred to the older tertiary formations. Probably this marl is a continuation of that of Richmond, but it is full of many new forms, associated with those common in the earth of the latter locality. It is an interesting fact, (first observed by Mr. Hamlin Lee,) that the common Scallop (Pecten maximus), as well as the Barnacle (Balanus), feed on diatomaceÆ, and their stomachs generally contain numerous cases of Coscinodisci, Dichtyochi, Actinocycli, &c.: a slide prepared and mounted with the contents of the stomachs of these mollusks, presents an assemblage of forms identical with those found in the tertiary earths of Virginia. In the mud of the quicksands on the shore at Brighton, Mr. Reginald Mantell found recent Coscinodisci, &c. associated with fossil polythalamia that had been washed out of the chalk, and precipitated with the frustules of the recent diatomaceÆ, into the sediments now in progress. The prevalence of marine and fresh-water forms in the same deposit is not unusual; and the remarks of Dr. Bailey on this fact are so pertinent, that I insert them, as a salutary caution against hasty generalizations on subjects connected with these investigations. After describing a species of Galionella (G. moniliformis), as an inhabitant only of salt and brackish water, and stating that he had also I must here close this extended notice of the fossil remains of a class of vegetable organisms, which, though for the most part invisible to the unassisted eye as individual forms, constitute by their inconceivable multitudes an important element in the formation of sedimentary deposits. The fact of their having been formerly treated of as animalcules, and generally regarded as belonging to the animal kingdom, rendered a full consideration of the phenomena necessary, in order to place the subject before the reader in a clear and comprehensive point of view. Confervites.—The cellular aquatic plants named ConfervÆ are sometimes found in transparent quartz pebbles, and in chalk, appearing as delicate simple or branched filaments, which, by the aid of the microscope, are seen to be Lign. 8. Confervites Woodwardii; nat. Chalk. Norfolk. FOSSIL FUCOIDS. Fossil Fucoids.—Of the tribe of AlgÆ which comprises the sea-weeds that are not articulated, many fossil species occur in very ancient, as well as in modern, fossiliferous deposits. In the Lower Silurian rocks of North America, beds of limestone of great extent are full of a large digitated Fucus (Fucoides Alleghaniensis). Chondrites.—These fossil algÆ approach nearest to the living species of Chondrus (hence the name of the genus). The frond is thick, branched, dichotomous, with cylindrical Lign. 9. Chondrites Bignoriensis; nat. Malm-rock. Bignor, Sussex. The tertiary marls and limestones of Monte Bolca yield several beautiful species of AlgÆ, one of which is figured in Of the little plants comprised in the class of cellular cryptogamia, which have stems, leaves, and fructification, but no true vessels, two or three species of Moss and Liverwort have been met with in tertiary strata. Mosses as well as Fuci are occasionally imbedded in quartz pebbles, in which they appear of their natural colour, and apparently floating in the transparent medium. A beautiful green moss, with a Conferva twined round its base, is figured Lign. 11, p. 104, from a specimen described by the late Dr. Macculloch. It is supposed to be related to Hypnum (Geol. Trans. vol. ii.). MOCHA-STONES. Moss-agates and Mocha-stones.—The beautiful siliceous pebbles called Moss-agates, and Mocha-stones, will so often come under the notice of the collector, that, although but extremely few, if any, of these objects contain organic remains, the arborescent substances they inclose being merely metallic oxides, a few remarks on their nature may be expected. The late Dr. Macculloch paid considerable attention to the investigation of these bodies, and believed that some of the objects imbedded in the pure and compact quartz were really of vegetable or animal origin; the specimen figured Lign. 10 Delesserites (Fucoides) Lamourouxii. Monte Bolca. (VÉg. Foss. Br.) Lign. 11. Moss and Conferva, in transparent quartz, × 3. M. Brongniart, who carefully examined a great number of agates and pebbles, with the view of determining if vegetable substances were ever imbedded in them, could not detect a single instance in which the apparent mosses, confervÆ, or algÆ, were organic; in every case the mineral origin of the pseudo-vegetation was, in his opinion, unequivocal. Some of the beautiful green arborescent bodies in quartz pebbles, even under the microscope, present so close a resemblance to confervÆ and mosses, that it is difficult to persuade oneself they are not vegetable structures; but the observations of M. Brongniart appear to me conclusive as to their mineral nature. Vascular, or Acrogenous Cryptogamia.—These plants, as the name implies, possess a more complicated structure than the preceding, having vascular tissue as varied as in the phanerogamia. EquisetaceÆ.—The common species of Equisetum, or Marestail, is a plant that grows in marshy tracts, and on the banks of ditches and rivers; it has a jointed stalk, garnished with elegant sheaths which embrace the stem, and verticillate linear leaves: it attains a height of two feet, and is half an inch in diameter. In the fossil state there are many plants allied to the Equisetum, but only a few that are generically the same. Equisetum Lyellii, A transverse slice of the stem exhibits under the microscope a cellular structure filled with calc-spar, and forms a beautiful object when viewed with the polarizing apparatus. This plant occurs in many localities of the Wealden in Sussex and Kent; from the railway cuttings near Tonbridge, I collected several fine specimens; it is met with also in the cliffs near Hastings. Lign. 13. Equisetites columnaris. (Ad. Brongn. Pl. 13.) Lower Oolite. Whitby.
Equisetites columnaris. Lign. 13.—A gigantic species of Equisetum abounds in the strata of the lower division of the Oolitic or Jurassic formation of Yorkshire, and many This plant is a true equisetum, differing chiefly from existing species in its gigantic size and arborescent character. The sheaths surrounding the stem, and the verticillate linear leaves, are preserved in some examples: and in all, the furrows left by the imprints of the sheaths are more or less strongly impressed. The stem is not channelled throughout, as in Calamites, the carboniferous plant whose stems at first sight might be mistaken for those of Equisetites, but which are entirely distinct, as will be explained hereafter. The Equisetites columnaris is peculiar to the Oolite; it does not occur in the coal-measures. Specimens have been discovered which indicate a height of twenty feet, and a diameter of several inches. A small species of Equisetum (Eq. Brodiei Lign. 14. Calamites decoratus. 1/3 nat. (Ad. Brongniart. Pl. 14.) Coal Formation. Yorkshire.
CALAMITES. Calamites. Lign. 14, 15.—Stem articulated, regularly furrowed longitudinally, the articulations naked, or studded with tubercles. The plants of this genus were supposed to be related to the marestail, but to differ in the absence of the encircling sheaths, and in being uniformly striated; but an examination of specimens in a better state of preservation than those previously known, shows their affinity to the gymnosperms. Some of the species are of a gigantic size, being from one to three feet in diameter, and from thirty to forty feet in height. Calamites abound in the coal formation, and must have constituted an important feature in the forests of the carboniferous period; they occur also in more ancient deposits, and some species belong to the earliest terrestrial Flora of which any vestiges are known. In most instances when specimens are found lying in the same plane with the strata, they are pressed flat, but those occurring in a vertical position retain their natural cylindrical form. An outer crust or cylinder of coal generally invests the stem, but traces of the internal structure are rarely preserved. The Calamite consists of a large central column of tissue, surrounded by a ligneous cylinder. The central part has in most instances perished after the death of the plant, and the cavity thus left been filled up with mineral matter. As the hollow ligneous zone is almost always carbonized, and very friable, it is seldom attached The true external surface of the cortical investment is marked with longitudinal striÆ, without any indications of joints or constrictions; but the position of the original articulations is indicated in some specimens by the presence of small verticillate scars, to which leaves were appended Lign. 15. Calamites, in Coal Shale.
The stellate appearance on the upper part of the stem figured in Upright stems of Calamites occur in the Coal formation near Pictou, in North America; and in one example a group of ten or twelve stems, covering an area of two square feet, sprung from one root. FOSSIL FERNS. Filicites, or Ferns. We now arrive at the consideration of one of the most interesting families of the vascular cryptogamia that adorned the Flora of the ancient world, and the living species of which impart beauty and elegance to the scenery of the countries where they prevail. The most essential character of these vegetables, is that of developing their fructification on the leaves; a fact familiar to every one who has even but cursorily examined the Polypody growing on our walls, or the Brake of our hedge-rows and commons. The largest species of British ferns scarcely exceed four or five feet in height; but the arborescent or tree-ferns, of warm climates, attain an altitude of from thirty to forty feet. There is too this peculiarity in the arborescent forms, that while in our indigenous species the leaves surround the stem, and incline towards the upper part of the plant, the foliage of the former bends downwards, Lign. 16. Pecopteris Sillimani; nat. Coal Shale. Ohio.
The leaves of our branched ferns are persistent, and when shed, the markings left by their attachment to the stalk are soon obliterated. In the arborescent ferns, on the contrary, the petioles become detached from their bases, and fall entire, leaving scars or cicatrices on the stem; and these impressions are so regularly and symmetrically disposed, as to afford characters by which the trunks may be distinguished from those of other trees. The stems of the tree-ferns are therefore easily recognized in a fossil state externally, by their cylindrical forms without ramification, and by the regular disposition and peculiar character of the From the elegance and diversity of form of their foliage, fossil ferns are the most remarkable and attractive vegetable remains in the ancient strata. The greater number are from the coal deposits, the fern-leaves generally occurring in the schists or shales that form the roof of the beds of coal. Many of the strata are made up of carbonized fern-leaves and stems closely pressed together. The roof of a coal-mine, when newly exposed, often presents a most interesting appearance, from the abundance and variety of leaves, branches, and stems, that occur either in relief, or impressed on the dark glossy surface. The specimens selected for illustration exhibit the principal modes of venation on which the genera are founded. The fossil genera have been established by M. Ad. Brongniart, from the form of the leaves and the characters of their venation; that is, the distribution of the vessels. In the following descriptions some botanical phrases are necessarily employed; a few terms of frequent occurrence are explained in Pachypteris Lign. 17. Pachypteris lanceolata. Inferior Oolite. Whitby. Lign. 18. Sphenopteris elegans Coal-shale, Waldenburg, Silesia. FOSSIL FERNS. SPHENOPTERIS. Sphenopteris (wedge-leaf). The ferns of this genus are extremely elegant, and comprise upwards of forty species. A beautiful Sphenopteris (S. affinis, Wond. p. 716,) occurs abundantly in the fresh-water carboniferous It is so rarely that the fructification of any species of Sphenopteris is preserved in a fossil state that I am induced to figure a leaflet of a remarkable plant, of this genus from the fluvio-marine oolitic deposits of Scarborough. This fossil fern closely resembles certain species of Dicksonia (natives of New Granada). Each segment of the leaflet or pinnate is dilated at the apex into a reniform indusium; no capsules are visible, the fructification being, probably, in a young state.
In the Wealden deposits, both of England and Germany, several species of Sphenopteris abound; one of which (Foss. Tilg. For. 1827), often occurs in the calciferous grit of Tilgate Forest, in a beautiful state of preservation: a small branch is figured in Lign. 21. Cyclopteris trichomanoides; a single leaflet; nat. Oolite, near Scarborough. Cyclopteris (round-leaf). FOSSIL FERNS. NEUROPTERIS. Neuropteris (nerved-leaf). Lign. 22.—The fronds are pinnate or bipinnate; the leaflets more or less ovate or cordiform and entire, adhering to the rachis by their centre only; veins very fine, arched, rising obliquely from the base of the leaflet; the midrib does not extend' to the apex of the leaflets, but terminates by subdividing into veins. Lign. 22. Neuropteris acuminata; nat. In Coal-shale, Yorkshire. This is a very numerous genus, comprising thirty or more species, which are principally found in the coal-shale. Some of these plants bear a general resemblance to the Osmunda regalis, but differ in their essential characters; their leaflets often form the nuclei of ironstone nodules. Glossopteris (tongue-leaf). Lign. 23.—Leaves simple, sub-lanceolate, gradually contracting towards the base; midrib thick at the base, and vanishing towards the apex of the leaf; veins very fine, curved, oblique, frequently dichotomous,
Odontopteris (tooth-leaf). Anomopteris (anomalous fern—so named because the plants differ from all recent and fossil ferns). Lign. 25. Anomopteris Mougeotii; nat. New Red Sandstone; Sultz-les-Bains, near Strasburgh.
FOSSIL FERNS. TŒNIOPTERIS. Toeniopteris (wreathed fern). Lign. 26.—Leaves simple, entire, straight, with parallel margins, traversed by a strong midrib, which extends to the apex; secondary veins, simple Lign. 26. Toeniopteris latifolia; fragment of a frond; nat. Stonesfield Slate. Lign. 27.
Pecopteris (embroidered fern). This genus embraces a very large proportion of the ferns which have contributed to the formation of the coal, and whose leaves and stems are preserved in the associated strata. The originals of many species were undoubtedly arborescent, and attained a large size; some leaves four feet wide, and of a proportionate length, have been observed. More than one hundred species are determined. An American species (Pecopteris Sillimani) is figured in illustration of certain botanical terms, Lign. 16, ante, p. 110. Several species of Pecopteris occur in the fluvio-marine oolitic deposits near Scarborough, and leaves in fructification are not uncommon: fig. 1, Lign. 27, represents a leaflet slightly magnified. Lign. 28. Lonchopteris Mantelli. Wealden, Tilgate Forest.
FOSSIL FERNS. LONCHOPTERIS. Lonchopteris (spear-leafed.) The three known species which compose this genus resemble Lign. 29.
Phlebopteris (veined-leaf). Lign. 29.—Leaves pinnated; leaflets with the margin entire, or crenulated, the The foliage of these remarkable ferns has been mistaken for the leaves of dicotyledonous plants; but M. Brongniart has demonstrated that they belong to the present family. Six species have been found in the Oolite and Lias. Lign. 30. Clathropteris meniscoides. Portion of a leaflet: the original 11/2 ft. long. Wealden? Scania. FOSSIL FERNS. CLATHROPTERIS. Clathropteris (latticed-leaf). Lign. 30.—Leaf deeply pinnatifid; leaflets elongated, traversed by a strong midrib extending to the apex; secondary veins numerous, simple, parallel, almost perpendicular to the midrib, united by transverse branches, which, with the finer veins, produce on the surface of the leaf a net-work of quadrangular meshes. This genus was instituted by M. Brongniart, for the reception of some very large fern-leaves from the shale of Hoer, in Scania, which resemble in structure the foliage of the recent Polypodium quercifolium, a native of the East Many other genera of fossil ferns have been established from the form and venation of the leaves, and are described in Brit. Foss. Flor., and other British and foreign works. Stems of arborescent Ferns.—Notwithstanding the profusion with which the foliage of many kinds of ferns is distributed throughout the coal formation, the undoubted stems of plants of this family are rarely met with; for the numerous tribe called SigillariÆ is now removed altogether from this class. It may, however, admit of question whether much of the foliage which, from the analogy of structure, has been referred to ferns, may not have belonged to those trees; for as in the animal kingdom, so in the vegetable, distinct types of living organisms are often found blended in the lost races; and as the stems of recent tree-ferns are even more durable than their leaves, it seems impossible to account for their absence in strata, that inclose entire layers of the foliage matted together. A few fossils, supposed to possess the essential characters of recent fern-stems, have been discovered, and arranged under the following genus. FOSSIL FERN-STEMS. Caulopteris (fern-stem). Lign. 31.—Stems not channelled, marked with discoidal, oblong, or ovate scars, arranged longitudinally; vascular cicatrices numerous. Lign. 31. Caulopteris macrodiscus. Coal. The fragment of stem here figured, resembles the trunks of some recent tree-ferns in its proportions, and in the number, disposition, and size, of the scars of the leaf-stalks; but these markings differ in their more lanceolate form, and pointed terminations, and in their peculiarly striated surface, from those of any known existing species. Psarolites (Silicified Fern-Stems).—In the New Red sandstone, near Hillersdorf, in the neighbourhood of Chemnitz, in Saxony, silicified stems, apparently of tree-ferns, occur in great numbers. They are remarkably beautiful, and the organization of the original is so well preserved by the silex, that slices, examined by the microscope, display the peculiar structure almost as perfectly as if the plants were recent: transverse sections exhibit the arched bundles of vascular fibres which compose the ligneous cylinder, surrounded by the cellular tissue. From the stellated markings produced by sections of the vessels that compose the tissues, and which are visible to the naked eye, these fossils have obtained the popular name of Staaren-stein, or Star-stone. The external surface of the specimens I have examined has a ligneous structure, and is of a dark reddish brown colour; internally the stems are of a dull red, mottled with various An excellent work ("Dendrolithen") on these fossils, in which thirty species are described, has been published at Dresden by M. Cotta; who arranges them under the genus Psaronius or Psarolites. The stem is composed of two distinct parts; an outer zone, consisting of a great number of nearly cylindrical bundles of vessels, supposed to have been roots which proceeded from the stem near its base; and an inner part or axis. In the outer portion, the fossil air-roots have a vascular tissue, but there is often a delicate cellular tissue interposed. In the axis the vessels form zigzag or wavy bands, resembling those of ferns. Dr. Buckland has discovered in the New Bed sandstone formation at Allesley, near Coventry, silicified trunks of coniferous trees, and it is not improbable that further research in that locality may bring to light fern-stems like those of Chemnitz. SigillarlÆ and StigmariÆ. SIGILLARLÆ AND STIGMARIÆ. Among the most common and striking objects that arrest the attention of a person who visits a coal-mine for the first time, and examines the numerous vegetable relics that are profusely dispersed among the heaps of slate, coal, and shale, are long flat slabs, from half an inch to an inch thick, having both surfaces longitudinally fluted, and uniformly pitted with deep symmetrical imprints; these are disposed with such perfect regularity between the grooves, that the specimens are often supposed, by persons not conversant with palÆontology, to be engraven stones, and not natural productions. These fossils are the flattened trunks of gigantic trees covered by the bark in the state of coal; the regular imprints on the surface, being the scars left by the separation of the petioles or leaf-stalks, as in the arborescent ferns previously examined. The name Sigillaria, commonly applied to these fossils, is derived from sigillum, a seal, and alludes to the regular and uniform pattern of the imprints on the surface. These stems are from a few inches to several feet in diameter, and the largest attain a height of sixty feet; they are generally found lying in a horizontal position in the strata, and quite flat, from the pressure produced by the superincumbent rocks; but when the trunks are in an erect position, and at right angles to the plane of the beds, the cylindrical form of the original is preserved. A remarkable instance, in which five stems of Sigillaria were standing upright, with their roots in the soil below, apparently in the position in which they grew, was brought to light a few years since, in forming the Bolton and Manchester railway. An excellent Memoir on this discovery, with illustrations, by Mr. Hawkshaw, is given in Geol. Trans, vol. vi. pl. xvii. See Pict. Atlas, p. 198; and Petrifactions, p. 36. Lign. 32. Base of a Trunk of a Sigillaria. with roots, standing erect with five other stems, in Carboniferous strata. (The original is four feet high.) In the stratum through which the roots extend, a considerable quantity of the fossil cones, called Lepidostrobi, hereafter described, were imbedded (see Lign. 40). A thin layer of coal which invested the stems, was evidently the ERECT STIGMARIÆ. Many other instances have been noticed of SigillariÆ standing more or less erect in the strata. In forming the railway tunnel at Claycross, five miles south of Chesterfield, through the middle portion of the Derbyshire coal-measures, in 1838, a group of nearly forty trees (SigillariÆ) was discovered, standing not more than three or four feet apart, at right angles to the plane of the strata. The most remarkable instance hitherto observed, is on the Lign. 33. SigillariÆ; in Coal-shale.
SIGILLARLÆ. The stems of SigillariÆ vary in size from a few inches to five feet in diameter; and in length from five to sixty feet; they gradually taper from the base to the summit. A specimen measured by M. Brongniart was forty feet long, one foot in diameter at the base, and but six inches at the top, where it divided into two equal branches. These stems may be readily distinguished from those of other trees with Lign. 34. Sigillaria Saullii. Carb. Manchester.
Internal Structure of SigillariÆ.—Our knowledge of the structure of this numerous tribe of plants, has received an important accession by the discovery of the silicified fragment of a stem, which, fortunately for the advancement of science, was placed at the disposal of M. Adolphe Brongniart. It has been described and illustrated by that eminent botanist, in a memoir which is one of the most valuable contributions to fossil botany that has hitherto appeared. Lign. 35. Silicified Stem of Sigillaria elegans. Autun. France.
The annexed figure (Lign. 35) is an outline of the specimen, of the natural size; but this sketch is a mere plan or SIGILLARLA ELEGANS. The external surface of this specimen possesses the characteristic markings of the insertion of the leaf-stalks of Sigillaria elegans. The internal organization, as seen in the transverse section, is as follows:— a. The centre, filled with silex; it exhibits no traces of structure. b. The zone which surrounds the interspace on which this letter is placed, is composed of bundles of vascular tissue. A portion of one of these bundles, highly magnified, is represented in Plate V. fig. 7. The inner circle of this zone, indicated by the convex undulating line, is made up of medullary vascular tissue; the external circle is divided by rays, and is composed of woody fibre, constituting a ligneous cylinder. One of the spiral vessels (fig. 3), and another showing a remarkable difference of structure in a short space (fig. 2), as seen in a longitudinal section of the medullary tissue, are figured in Lign. 35. The ligneous cylinder is surrounded by a band of cellular tissue, and the space between this and the cortical integument is occupied by silex, in which there are but obscure traces of structure. The inner layer of bark, f, is composed of elongated cells, Upon instituting a comparison between the fossil and the stems of those recent plants which present the closest analogy to it, M. Brongniart was led to conclude that the SigillariÆ constituted a peculiar extinct family, belonging to the great division of gymnospermous dicotyledons. The SigillariÆ were tall erect trees, with a regular and cylindrical stem, without side branches, but dichotomous towards the summit. Their superficial bark was hard and durable, channelled longitudinally, bearing leaf-scars that are of a rounded form above and below, and angular at the sides, often oblong in relation to the stem, and having three vascular pits, one central and small, and two lateral of a larger size. The internal structure bears most analogy to that of the CycadeÆ, and the foliage consisted of long linear carinated leaves. The SigillariÆ, therefore, differ essentially from the arborescent cryptogamia, which they somewhat approach in having scalariform vascular tissue, symmetrical and regular leaf-scars, and branchless trunks. More than fifty species have been determined. STIGMARIA. Stigmaria. Lign. 36.—This extended notice of the structure of the SigillariÆ,.will enable us to understand the nature of the fossil vegetables termed StigmariÆ, or spotted-stems, which abound in the beds of under-clay of most coal-fields, as stated in a former part of this work (ante, p. 81.). These bodies when uncompressed are of a cylindrical form, from one to six or seven inches in diameter, and of considerable length—sometimes upwards of twenty feet—and gradually diminish in size towards their termination. The surface is marked with distinct pits or areolÆ, of a circular or oval form, with a small tubercle in the centre of each, disposed around the stem in a quincunx and somewhat regular order. Lign. 36. Stigmaria ficoides. Carboniferous. Derbyshire.—1/4 nat.
When StigmariÆ are observed in the under-clay, to which stratum they are principally confined, long, tapering, subcylindrical fibres, often several feet in length, are seen affixed to the tubercles with which the surface is covered; their form and mode of attachment are shown in Lign. 36. Instances occur in which several StigmariÆ spring from a common centre, of a dome-like form, whence they radiate in every direction (Bd. pl. lvi. fig. 8), and the main branches divide and subdivide till they are lost in the surrounding rock. The nature of these fossil vegetables was long a perplexing question, for no specimens had been found in connexion with any of the stems, branches, or foliage, that abound in the coal deposits. At length, the discovery of a dome-shaped mass, to which were attached numerous StigmariÆ, seemed to afford a clue to the solution of this botanical problem; and it was concluded by the eminent authors of the "Fossil Flora of Great Britain," that the original belonged to a tribe of plants which inhabited swamps, or still and shallow lakes, and were characterized by a low truncated stem, having long horizontal branches beset with cylindrical, and, probably, succulent leaves, that either trailed on the surface of the swamp, or floated in the water. But within the last few years, the occurrence in various carboniferous deposits of erect stems of SigillariÆ, has shown that the StigmariÆ are nothing more than the roots of these and other congenerous trees; an opinion maintained by the Rev. H. Steinhaur more than thirty years ago, and subsequently affirmed by M. Adolphe Brongniart, who found, on examining microscopically the internal structure of a silicified specimen in which the vascular tissue was preserved, that it bore as close an analogy to that of the SigillariÆ, as exists between the roots and trunks of certain dicotyledonous trees. The annexed figure, Lign. 37, represents the transverse section of a small Stigmaria, with the axis displaced from its natural situation; this circumstance, as well as the corresponding external groove, has arisen from compression, by which the tough cylinder has been forced from its original position in the middle of the soft cellular tissue, to one side. Lign. 37. Transverse Section of Stigmaria ficoides; nat. (M. Adolphe Brongniart.) This specimen shows that the cylinder (a in Lign. 36) is formed of bundles of vascular tissue, disposed in rays. The central axis is thus shown to be a cylinder composed of bundles of vessels, disposed in a radiating manner, and separated from each other by medullary rays; the whole constituting a ligneous zone resembling that of Sigillaria (see Lign. 35); but the inner circle of medullary tissue seen in the latter is altogether wanting. This difference is similar to that observable in the stems or branches of a dicotyledonous tree, in which the woody cylinder is associated internally with bundles of medullary tissue, and the roots of the same tree that are destitute of them. Part of a vascular bundle from the woody tissue of a Stigmaria, seen Lign. 38. Erect Stem of a Sigillaria, with roots. Coal Mine, near Liverpool.
ERECT SIGILLARLA WITH ROOTS. This opinion of M. Brongniart was confirmed by the discovery, in 1843, at St. Helen's, near Liverpool, of an upright trunk of a Sigillaria, nine feet high, with ten roots eight or nine feet in length, still attached, and extending in their natural position. These roots are undoubted StigmariÆ of the usual species, S. ficoides; and the radicles, formerly considered leaves, are spread out in all directions, to the extent of several feet. In the Pictou coal-field of Cape Breton, in Nova Scotia, similar facts have been brought to light; the remarkable phenomena existing in that locality, of successive carboniferous deposits containing scores of erect trees with roots spreading into their native soil, presenting peculiar facilities for verifying the observations made in England. In an interesting memoir on the coal-fields of Nova Scotia, Mr. Richard Brown has given a detailed account of numerous examples of stems of SigillariÆ, and of Lepidodendra, (a tribe of gigantic club-mosses of which we shall presently treat,) with the roots attached; these roots, in every instance, had the characters and structure of StigmariÆ. In one instance, the stem of the tree was broken off close to the roots, and the hollow cylinder of bark was bent down and doubled over by the pressure of the surrounding mud, so as effectually to close up the aperture, and leave only a few irregular cicatrices converging near the apex; this fossil explains the true nature of the "dome-shaped" plant figured in the Fossil Flora, and in Dr. Buckland's Essay. LEPIDODENDRON. Lepidodendron (scaly-tree). Lign. 39.—Stems cylindrical, covered towards their extremities with simple, linear, or lanceolate leaves, which are attached to elevated rhomboidal spaces, or papillÆ; papillÆ marked in the upper part with a large transverse triangular scar; lower part of the stem destitute of leaves. Lign. 39.
In Coal-shale, Newcastle. The remains of this tribe of plants abound in the coal formation, and rival in number and magnitude the Calamites and SigillariÆ previously described. These trees have received the name of Lepidodendra, from the scaly character of their stems, occasioned by the angular scars left by the separation of the foliage, as is the case in arborescent ferns: the term, however, simply indicates the appearance, for the surface is not imbricated. Some of these trees have been found almost entire, from the roots to their topmost The internal organization of the stem of Lepidodendron differs from that of Sigillaria, in the absence of the woody cylinder and medullary rays which constitute so peculiar and important a character in the latter. The Lepidodendra have only an eccentric, vascular, medullary zone, the interval between which and the bark is filled up by cellular tissue. The fruit of the Club-mosses is an oval or cylindrical cone, which in some species is situated at the extremity of the branches, and constitutes an imbricated spike. Now associated with the stems of the Lepidodendra, and very often in masses of their foliage, and in some instances attached to the extremities of the branches, are numerous oblong, or sub-cylindrical, scaly cones, garnished with leaves. These have received the names of Lepidostrobi (scaly-cones), and are unquestionably the fruit of the trees with which they are imbedded. LEPIDOSTROBUS. Lepidostrobus. Lign. 40.—A cylindrical strobilus or cone, imbricated from above downwards, composed of winged scales, terminating in rhomboidal discs: the axis traversed by a longitudinal cavity or receptacle. These fossils have long been known to collectors, and are figured by Martin (Petrif. Derbiensia), Parkinson (Org. Rem. vol. i. pl. ix.), and others. They are cylindrical imbricated bodies, rounded at both extremities, from two to six or seven inches in length, and one or two inches in circumference. When broken asunder, a cylindrical cavity is exposed, which is sometimes hollow, but commonly filled with mineral matter; and when specimens are found imbedded in shale, the cone is fringed with linear-lanceolate bracteÆ, as in Lign. 40. Lepidostrobi, the fruit of Lepidodendra; nat. Coalbrook Dale.
The figures in Lign. 40, represent the usual characters of these fruits. Of the young specimen, (fig. 3,) situated at the termination of a branch, M. Brongniart observes, "qu'il est impossible de ne pas reconnaÎtre pour un Lepidostrobus Triplosporite.—Additional light has recently been thrown on the structure of the Lepidostrobi, by Dr. Robert Brown's examination of a silicified specimen of the upper part of a strobilus, in which the internal organization is beautifully displayed. The reader specially interested in this department of fossil botany should refer to the original memoir by the illustrious President of the LinnÆan Society, with the accompanying plates that admirably exhibit the microscopic analysis of the structure of this remarkable fossil; a slice of which was shown me some years since by the late Marquis of Northampton. Lycopodites.—Species of true LycopodiaceÆ occur in tertiary marls; a beautiful specimen, from Germany, Lycopodites BenettiÆ, is figured Wond. p. 723. HALONIA. KNORRIA. Halonia; Knorria. Lign. 41.—Associated with the plants already described from the coal-measures, there are trunks and branches of other trees, presenting peculiar and but imperfectly known characters, which it will be convenient to notice in this place. Fragments of these stems are to be seen in most public collections of the carboniferous flora, and should be examined by the student, for figures and descriptions can convey but an imperfect idea of their nature. Mr. Denny, the intelligent and indefatigable Curator of the Leeds Philosophical Society, has given the following admirable summary of the distinctive characters of the stems of most frequent occurrence in the Coal, 1. Sigillaria.—Stem furrowed, not branched, leaf-scars small, round, much narrower than the ridges of the stem. 2. Favularia.—Stem furrowed, not branched, leaf-scars small, square, and as broad as the ridges of the stem. 3. Lepidodendron.—Stem not furrowed, branched, covered with lozenge-shaped scars in quincuncial order, each having a papilla in the upper part; the upper portion of the stem and branches with simple linear leaves; the lower portion destitute of leaves. 4. Halonia.—Stem not furrowed, branched, covered with indistinct rhomboidal marks, and tubercular projections disposed in quincunx. 5. Knorria.—Stem not furrowed, branched, marked with projecting scars of petioles disposed spirally. 6. Megaphyton.—Stem dotted, neither furrowed nor branched, leaf-scars very large, of a horse-shoe figure. 7. Bothrodendron.—Stem pitted, neither furrowed nor branched, scars of cones (?) obliquely oval. 8. Ulodendron.—Stem neither furrowed nor branched, covered with rhomboidal marks; scars of cones (?) circular. The characters of the roots called StigmariÆ (ante, p. 134.), and of the stems named Calamities (ante, p. 107.), and Equisetites (ante, p. 106.), are sufficiently distinct from the above to be easily recognized, I will briefly notice those not previously described. Lign. 41. Stems from the Coal Formation.
Halonia.—The specimens usually seen are mere sandstone casts having a thin carbonaceous crust; the stem is branched and beset with large elevated knobs, or subcortical protuberances, as shown in Knorria.—To this genus the authors of the Fossil Flora of Great Britain referred those stems which have projecting leaf-scars, arranged spirally. The beautiful specimen figured as Knorria taxina, Bothrodendron and Ulodendron.—These genera, together with Megaphyton, are stems of a very remarkable character, and are easily distinguished by the vertical rows of large and distant scars. The two first have two series of very deep oval depressions on opposite sides of the stems, arranged alternately in the specimens I have examined: from the size and form of these obliquely-oval cavities, it is supposed that they were formed by the attachment of cones, and not by petioles; but their real nature is involved in obscurity. In Megaphyton, the large ovate scars indicate the attachment of deciduous branches or gigantic leaves, which did not grow all round the stem, but in a regular order of superposition on each side. ASTEROPHYLLITES. Asterophyllites.—I shall conclude this notice of some of the most characteristic trees of the Carboniferous Flora, with an account of a tribe of plants whose remains are so 1. Calamodendron.—These are arborescent stems, ligneous internally, and covered with a smooth carbonaceous crust, without regular longitudinal striÆ, and not articulated; but the woody axis covered by this bark is deeply striated and articulated, resembling in this respect the true Calamites. These stems have a large central pith, or medullary column, surrounded by a ligneous zone, which is formed of radiated bands, without circles of growth: the structure of the carbonized bark is unknown. 2. Asterophyllites.—These are supposed to be the branches and foliage of the stems above described. 3. Sphenophyllum.—Plants, differing in the form of the leaves, but analogous in structure and mode of fructification to the Asterophyllites. 4. Annularia.—Herbaceous aquatic plants, distinct from the preceding. 5. Volkmannia.—These fossil plants are Asterophyllites in fructification. The Asterophyllites (Lign. 42) had branched articulated stems, with verticillate leaves, arranged perpendicularly to the branches which supported them: but as the foliage is in most instances partially concealed, the natural form is but seldom observable. The original plants are supposed to have been a tribe of The AnnulariÆ were herbaceous plants with verticillate foliage like the former, but the whorls were arranged on the same plane with the stems on which they grew, and their remains have a very elegant appearance when expanded in the coal schists. It is supposed that they were aquatic plants, and that the stems and leaves floated on the surface of the water. Sphenophyllum (wedge-shaped leaf). Lign. 43.—The fossil vegetables thus named, though somewhat resembling in their elegant verticillate foliage the Asterophyllites, differ essentially, and are regarded by M. Brongniart as herbaceous plants related to the MarsiliaceÆ, or Pepper-worts. The leaves are triangular, truncated at the summit, and very deeply lobed and dentated. The fructification consists of sessile axillary or terminal spikes, composed of verticillate bracteÆ, covering the receptacles. This mode of fructification resembles that of the Asterophyllites. Cardiocarpon.— Lign. 43.
Coal-Shale. Trigonocarpum. FOSSIL FRUITS. A figure of a fossil fruit from the Oolite—Carpolithes Bucklandi, is introduced in Lign. 44. Fossil Fruits, or Seed-vessels; nat.
The reader will observe that the fossil vegetables hitherto described belong, with but few exceptions, to the Carboniferous flora; and that the remains of Ferns, Calamites, SigillariÆ, and Lepidodendra, compose in a great measure those prodigious accumulations of mineral fuel, or coal, which supply the luxuries and necessities created by civilization. Our review of fossil plants will now assume somewhat of a botanical arrangement, and we proceed to notice some of the most characteristic vegetable forms of the secondary and tertiary formations. We commence our examination with those remarkable tribes of gymnosperms, the CycadaceÆ, which comprise the ZamiÆ and CycadeÆ. Fossil CycadaceÆ. The plants of this subdivision of the vegetable kingdom, from their singular structure and mode of growth, their simple cylindrical stems, and coronets of pinnated foliage, resembling that of certain palms, their usually gyrate vernation like that of the ferns, and their anomalous inflorescence and fructification, are objects of great interest to the scientific botanist; while the abundance of their fossil remains in the secondary formations renders them of the highest importance to the geologist. Lign. 45. Foliage and upper part of the Stem of Cycas revoluta 1/12 nat. In Kew Conservatory. As many kinds of Zamia The ZamiÆ are short plants, with stout cylindrical stems, beset with thick scales, which are the bases of the petioles that have been shed: towards the summit the stem is garnished with a crown of elegant leaves; the fruit resembles the cones of pines. The leaves are pinnated, and very tough; their venation is either parallel as in endogens, or dichotomous as in ferns, but never reticulated as in exogens: The CycadeÆ have the general aspect of the ZamiÆ, but differ in their fructification and other characters; and some species have the stem bifurcated towards the top, and attain a height of upwards of twenty feet; for example, C. circinalis. The stem in its internal structure The existing species of CycadaceÆ are exclusively natives of hot regions, and chiefly inhabit the West Indies, South Africa, Equinoctial America, Japan, New Holland, &c.; not one species is known in Europe: a fact in striking contrast with the abundance of fossil plants of this order, which occur throughout the secondary formations of England and the continent. No true cycads have hitherto been discovered in the carboniferous deposits; it is in the floras of the secondary epochs, from the new Red to the Cretaceous inclusive, that this tribe of plants forms an important feature. The foliage, stems, and fruits, occur in a fossil state; and as these organs cannot be referred with certainty to their respective plants, distinct genera are formed for their reception. Foliage.—From the tough and durable nature of the leaves, the foliage of the CycadeÆ occurs in a fine state of The leaflet of the recent Cycas is distinguished by a strong nervure, which runs along the middle; that of Zamia has no midrib, but fine parallel veins that pass direct to the margin.
Pterophyllum comptum. Lign. 46.—The general aspect of these fossils is shown in this figure of a leaf, referred to the genus Pterophyllum, which is characterized by leaflets, often slightly united at their base, truncated at the summit, of a quadrangular or oblong form, and having fine, straight, parallel veins. The leaves are ten or twelve inches long, and have fine lanceolate leaflets; they are abundant in the same beds, and are often associated with the cones or fruit ZAMITES PECTINATUS. Zamites pectinatus. Lign. 47.—In the Stonesfield slate, collocated with remains of reptiles, fishes, insects, and mollusks, leaves and fruits of cycads are occasionally met with. But few vestiges of the foliage of Cycads have been observed in the Wealden formation of England; one elegant leaf, however, of an undescribed species, was obtained some years since, from a sandstone quarry in Surrey, and is figured in my Geology of the South-east of England, p. 238; it is named in honour of my distinguished friend, M. Ad. Brongniart, Cycadites Brongniarti. The Wealden of the north of Germany is very rich in fossil CycadeÆ; my friend. Dr. Dunker, has figured and described twelve species in his admirable work on the organic remains of that formation. Fruits.—The cones or fruits which occur with the foliage of ZamiÆ in the carbonaceous shales and marls of the Oolite of the Yorkshire coast, are very fine, and have been described under the various names of Zamites Mantelli, Z. gigas, and Z. lanceolatus. An interesting memoir on the structure of these fossils, by James Yates, Esq. (a gentleman distinguished for his knowledge of the recent CycadaceÆ), is published in the Lign. 48. Fruit of Zamites Mantelli, (Brongniart); nat. From near Scarborough. The surface of the cone is concealed by the bracteÆ. Zamites Mantelli. It does not appear that the structure of the cone has been preserved in any of the specimens, so as to demonstrate the characters of the original; in all those I have examined, the surface of the fruit is concealed by the elongated bracteÆ, which are pressed flat, and adhere so firmly to the inclosed body, as to render it impossible to ascertain its nature. Zamites crassus. ZAMITES OVATUS. Zamites ovatus. Lign. 49. Fossil Fruits of Cycadeous Plants; 1/2 nat.
Zamites Sussexiensis.—At Willingdon, near Eastbourn, in Sussex, a cone nearly six inches long was discovered in a bed of Greensand, which abounds in fossil coniferous wood: it is of an elongated cylindrical form, and covered with hexagonal scales. I have provisionally named it Zamites Sussexiensis (Geol. Proc. 1843), as it presents a nearer resemblance to the fruit of ZamiÆ than to that of Conifers. Trunks and Stems of CycadaceÆ.—In this section I shall notice the fossil plants which occur so abundantly in the fresh-water deposits that overlie the marine oolitic limestone of the Isle of Portland, and which must be familiar to my readers, from the graphic account of the circumstances under which they occur, by Mr. Webster, and subsequently by Dr. Buckland, and Sir H. De la Beche. In my Wonders of Geology, p. 387, and Geol. Isle of Wight, p. 395, the geological phenomena of that most interesting locality, MANTELLIA NIDIFORMIS. Lign. 50. Silicified Trunk of Mantellia nidiformis (Brongn.); 1/4 nat. (Cycadites megalophyllus. Bd.) Wealden. Isle of Portland. a. Central mass of cellular tissue, b. Circle of ligneous plates, c. Zone of cellular tissue, d. False-bark. Mantellia. Lign. 50, 51.—The fossil CycadeÆ of the Isle of Portland were first described botanically by Dr. Buckland, (Geol. Trans, vol. ii. 2d Series,) under the name of Cycadeoidea; of which Memoir the account in Bd. p. 404, is an abstract. M. Ad. Brongniart, considering these plants as a peculiar type, referred them to a new genus, which he did me the honour to name Mantellia (Prod. Veg. Foss.). These stems or trunks are from one to two feet in height; the circumference of the largest not exceeding three feet. The stem is There are two species, which are readily distinguished by the form of the stems, and the difference in the size of the cicatrices left by the petioles. The most common kind is short, and spheroidal, and the leaf-scars are relatively large; its shape has caused it to be named "Crows' nest," by the quarrymen, who believe these plants to be nests that were built by crows in the trees of the petrified forest with which they are imbedded. The specific name (nidiformis) adopted by M. Brongniart, expresses this popular notion. Lign. 50. represents a fine example from the Portland Dirt-bed, which exhibits a structure altogether similar to that which characterizes the stems of recent cycadeous plants; namely, (a) a central mass of cellular tissue surrounded by circles of laminated ligneous rays or plates (b); then a zone of cellular tissue (c), and an external cylinder of false-bark (d). The mode of increase by buds, from germs in the axillÆ of the petioles, as in the living plants, is also distinctly seen. Lign. 51. Mantellia cylindrica. (Brongn.); 1/8 nat. (Cycadites microphyllus. Bd.) Wealden. Petrified Forest of the Isle of Portland. The other species is subcylindrical, and the leaf-scars are much smaller and more regular than in M. nidiformis, indicating a more delicate foliage, as expressed by Buckland's specific name: that of M. Brongniart refers to the cylindrical form of the stem. This plant was higher and more slender than its associate. Numerous buds are seen in the axillÆ of the petioles in the specimen figured. These fossils present, both externally and internally, a close relation to the bulbiform stems of the recent CycadeÆ, named Encephalartos, of South Africa. Neither the leaves nor the fruit are known: a cone found in the Dirt-bed of Portland, and attributed to these plants, appears to belong to the coniferÆ of the petrified forest. Examples of MantelliÆ have been found in the quarry of Portland-stone at Swindon, Wilts. CLATHRARIA LYELLII. Lign. 52. Clathraria Lyellii. Wealden. A branched example of the inner axis: the original 31/2 feet high. Clathraria From the imperfect state of the remains of these plants, the structure and affinities of the originals were very ambiguous, and the fossils have been placed by some eminent botanists with the LiliaceÆ, and by others with the AsphodeleÆ; their true botanical position is doubtless with the CycadaceÆ; for in some points they resemble the ZamiÆ, in others the CycadeÆ. The stem of the Clathraria is composed of a solid internal axis, the surface of which is covered with reticulated fibres; the large branched specimen of this part, figured in
The cortical zone is generally converted into a cylinder of stone, which in some examples separates from the axis. In a beautiful specimen of this kind, The axis is solid, and has its surface strongly marked with interrupted ridges. This surface has generally patches of vascular tissue adhering to it; and there are here and there deep pits, or lacunÆ, which probably contained a resinous secretion. Thin transverse sections of the axis, prepared with Canada balsam, and examined under the microscope, only give faint traces of cellular tissue.
I have spared neither trouble nor expense in endeavouring to detect the organization of this plant; numerous sections of stems have been cut, and examined microscopically, but very few exhibit any traces of structure; and in those which retain some vestiges of organization, the siliceous mass which permeates the vascular tissue, is not sufficiently transparent to yield satisfactory results. It can only be inferred that in their internal organization, as in their external characters, the ClathrariÆ were most nearly allied to the CycadeÆ or ZamiÆ. A remarkable specimen, ( This fossil is a portion of the summit of a stem garnished with persistent petioles, or leaf-stalks; it is fifteen inches in length, and nearly perfect at the top; and at the lower end, which has been broken off transversely, the inner axis (Lign. 56 a.), surrounded by the false-bark formed by the confluence and consolidation of the bases of the petioles, is exposed. The stem has been stript of the leaf-stalks at the lowermost part, and exhibits the characteristic lattice-like scars. The petioles are for the most part entire; some of them are abortive, and others, which have supported leaves, are marked on the summits with vascular pits, indicating that the foliage Lign. 56. Clathraria Lyellii; 1/4 nat. Chalk-marl. Bonchurch, Isle of Wight. The summit of a stem garnished with petioles; the lower part shows the cicatrices left by the removal of some of the petioles: a, the internal axis. On the sea-shore bounded by cliffs of Wealden rocks, in the Isle of Wight, water-worn portions of stems of ClathrariÆ are occasionally met with; and these are impressed with the lozenge-shaped areas left by the petioles, as in the specimen, Vestiges of roots, seed-vessels, and panicles, have been found in the Wealden, which may possibly belong to the Clathraria; but the evidence as to their presumed relationship is at present too vague to require further notice. Lign. 57. Clathraria Lyellii; 1/2 nat. Specimen, showing the water-worn external surface. ENDOGENITES. Endogenites erosa.—(Geol S. E. pl. i.; Tilg. Foss. pl. iii.; and by Dr. Fitton in Geol. Trans. vol. iv.)—The genus Endogenites was established by M. Ad. Brongniart for the reception of those fossil stems and woods, whose internal structure is endogenous, but which are too imperfect to be referred to any particular family. In this category must be placed certain silicified stems having a carbonaceous cortical investment, which I discovered in the strata of Tilgate Forest, in 1820. These fossils often occur in the layers of lignite which traverse the clay-beds in some parts of the Weald of Sussex. They are from one to eight inches in diameter, and five or six feet in length, and of very irregular shapes; I have not observed any indications of branches. Some specimens are subcylindrical in the middle, and gradually taper to a point at each end; others are of a depressed clavated form, like some of the CacteÆ or EuphorbiaceÆ. They are generally silicified, Large water-worn stems of Endogenites are occasionally washed out of the Wealden cliffs at Hastings, and in Sandown and Brook Bays, in the Isle of Wight. Fossil coniferÆ. FOSSIL CONIFERÆ. The other great natural order of Gymnospermous phanerogamiÆ, The Conifers are all arborescent, having numerous branches, which are in general disposed with much regularity. The leaves are commonly acicular or needle-shaped, narrow, and linear: in two or three genera, however, (Dammara, Podocarpus,) the foliage departs remarkably from the ordinary type, the leaves being broad and flat. The structure of the stem, though in its general characters essentially exogenous (see Plate IV. fig. 4),—that is, having a central pith, medullary rays, zones of vascular tissue, and concentric circles of growth,—differs in the almost entire absence of spiral vessels, and in the peculiar modification of the radiating bands of woody fibre, which are made up of uniform longitudinal vessels, and run parallel with the medullary rays. The lateral walls of these vessels have longitudinal rows of areolÆ, which are generally circular or elliptical, but when in contact are angular and polygonal: each areola has a small pore or punctation in the centre. These discs, glands, or ducts, as they are called, are variously arranged in different genera; they are generally confined to the contiguous and corresponding lateral surfaces of the fibres; and occur rarely, if ever, on the inner and outer aspects of the vessels. In the recent genus Pinus the rows of ducts are single in some species; in others both single and double series occur, but never more than two, and in the latter case the ducts are always parallel to each other (see pl. v. 3b. Wond. pp. 696, 725). But in the AraucariÆ, or Norfolk Island Pines, the vessels have double, triple, and sometimes quadruple, rows of discs, of smaller size than in the common pines; and in the double series, these bodies are always arranged alternately (Wond. p. 696. Bd. 56 a.); Mr. Nicol states that there are about 50 discs in the length of 1/20 inch, the diameter of each not exceeding 1/1000 inch. The form and arrangement of these ducts, and the structure of the medullary rays, are the characters on which the scientific botanist relies for the detection of the affinities of The great value of these data will be shown in the sequel. The stems, fruit, and foliage, of ConiferÆ, occur in the various fossiliferous deposits, from those containing the earliest traces of terrestrial vegetation to the newest tertiary strata; and a large proportion of the petrified wood found in the British formations belongs to trees of this order. The presence of rows of ducts on the ligneous fibres, which is peculiar to this division of gymnosperms, as we have already explained (ante, p. 58.), is so easily detected by microscopic examination, that the merest fragment of fossil coniferous wood retaining internal structure, may without difficulty be recognized. The number of rows, and the opposite or alternate arrangement of the areolÆ, are characters which, in the living pines and firs, enable us to refer the respective trees to European or exotic forms; but in the fossil coniferous wood, much diversity exists in other not less important points of structure, and for the successful cultivation of this department of fossil botany, works especially devoted to the subject must be consulted. To the English student, Mr. Witham's beautiful volume, "Observations on the Structure of Fossil Vegetables, Edinburgh, 1831," will be found a valuable guide. FOSSIL CONIFEROUS WOOD. Fossil Coniferous Wood.—The coniferous wood of the secondary formations of England, belongs for the most part to the Araucarian type: that is, the glands, when in double rows, are placed alternately, as in the Norfolk Island Pines (Wond. p. 696), and not side by side, as in the common European species of firs and pines (Bd. p. 486). Numerous sections of this kind of fossil wood are figured by Mr. Witham, from specimens obtained from Lennel Braes, on the banks of the Tweed, near Coldstream; and from near Allanbank Mill, in Berwickshire (Obs. Foss. Veg. p. 14); a fossil trunk, 40 feet long, discovered in Craigleith Quarry, near Edinburgh, at a depth of 136 feet, possessed the same structure. PalÆoxylon (coniferous wood of the Coal Measures).—The existence of coniferous trees in the Carboniferous flora, and the fact that their trunks and branches had contributed to the formation of coal, was first discovered and clearly demonstrated by Mr. Witham in the work to which reference has been made. Figures of the peculiar structure observable in thin slices of coal, are given in Obs. Foss. Veg. pl. iii. iv. v. This carbonized wood resembles that of the AraucariÆ in the multiple series of ducts, and their alternate arrangement; but the presence of thick compound medullary rays in these stems,—a character unknown in any living conifers,—led M. Brongniart to place them in a separate genus—PalÆoxylon (ancient wood); characterized by the presence of medullary rays formed of numerous layers of cells, which are not arranged in superimposed series, and that present a lanceolate or oval form, in a section perpendicular to their direction. Peuce.—Another species of coniferous wood from the coal is thus named; it differs from the former in the medullary rays being composed but of one layer of superposed cells. Araucarites (Dadoxylon of Endlechen).—This term is employed to designate the fossil wood whose structure is apparently identical with that of the living species of AraucariÆ, having the same kind of medullary rays, and the ligneous fibres studded with discs or areolÆ, which are polygonal, often hexagonal, and disposed in several alternating series. This wood is common in the Lias, Oolite, Wealden, and Chalk. Drifted fragments of coniferous wood of this type occur in the Stonesfield slate, associated with leaves and fruits of cycadeÆ, and with marine shells, bones of reptiles, fishes, and mammalia; at Scarborough, with the ferns and zamiÆ previously described; at Swindon, in the Portland oolite, with belemnites, ammonites, trigoniÆ, &c. STERNBERGIA. Sternbergia.—To the Araucarian tribe, according to the recent investigations of Professor Williamson, must be referred certain fossil stems found in the coal-measures, and named SternbergiÆ. Petrified Forests of Conifers.—The most remarkable assemblage of fossil conifers is that presented in the well-known quarries in the Island of Portland, to which allusion was made when describing the MantelliÆ obtained from that locality (ante, p. 157.). Referring to Wond. p. 385, No foliage has been observed in connexion with these trees; not a leaf has been found in the rocks: a cone, At Brook-point, in the Isle of Wight, an equally interesting fact may be observed. At the base of the cliff, which is entirely composed of Wealden clays, shales, and sandstones, there is a vast accumulation of petrified firs and pines, imbedded in the indurated grit that forms the lowermost strata on the sea-shore, and of which the reefs and rocks, produced by the encroachments of the sea, and that extend far from land, are composed. These can be examined at low-water, and the observer, upon lifting up the fuci and algÆ which cover them, will find the rocks and masses of stone to consist of petrified trunks of coniferÆ. There are no erect trees as in Portland; on the contrary, the stems are prostrate, and lie confusedly intermingled, and associated with bones of Iguanodons and other reptiles, and large mussel-shells; the whole presenting the characters of a raft of forest trees which had drifted down the stream of a vast river, and entangled in its course the limbs and carcasses of animals that were floating in the water, and the shells that inhabited the river, and at length became submerged in the bed of the delta or estuary. Both foliage and fruit have been found in the Wealden deposits at Brook, and will be described hereafter. In the sands of the Desert of Sahara, in Egypt,—among the mammalian bones of the Sub-Himalayas,—and in the tertiary deposits of Virginia associated with cycads,—drifted trunks of conifers have been discovered. Fossil trees of this family also occur in various localities in Australia and Van Diemen's Land, the wood of which is in some parts calcified, and in others silicified. The same trunk often has externally a white friable calcareous zone, several inches thick, traversed by veins of silex, or opaline chalcedony, while the centre is a silicified mass; in FOSSIL CONIFERÆ OF AUSTRALIA. A fossil pine forest, on the eastern coast of Australia, in the inlet called Lake Macquarrie, is described by the Rev. B. Clarke, as occurring at the base of a mountain range, composed of conglomerate and sandstone, with subordinate beds of lignite; an alluvial plain extends to the water's edge, covering the sandstone rock which is seen in situ beneath. Throughout this plain, stumps of fossil trees project from the ground, and present the appearance of a forest in which the trees have all been broken off at the same level. At the distance of some yards from the shore, a reef is formed by vertical rows of the petrified stems, which project out of the water. Many of the fossil stems on the strand have the remains of roots extending into the sandstone below the alluvial deposit, and, like those in the Island of Portland, are in some instances surrounded by an accumulation of rock, which forms a mound of a higher level than the surface of the stratum. The trunks are, generally, three or four feet high, and from two to six feet in diameter. The wood is silicified, and veins of chalcedony traverse its substance between the concentric rings and medullary rays; in several examples, from 60 to 120 annual circles of growth In the valley of the Derwent, in Australia, opalized coniferous trees of a similar character were observed under very extraordinary circumstances, by the distinguished traveller, Count Strzelecki. Truncated stems were found standing erect in a bed of scoriaceous basalt (lava) and trachytic conglomerate: but in some instances only basaltic casts of the trunks remain. This curious phenomenon can only be explained by supposing the silicified stems to have resisted the intense heat of the incandescent lava, while trees placed in circumstances unfavourable to their petrifaction were consumed: but the latter, being either saturated with water, or fresh and green, were burnt slowly, and left cylindrical moulds in the cooled basaltic scoriÆ, with impressions of the external surface of the bark; these moulds were filled Tip by a subsequent eruption, and thus basaltic casts of the consumed trees were formed. Coniferous Wood in Oxford Clay.—It would occupy too much space to notice the numerous localities in which fossil remains of conifers occur in the Liassic and Oolitic formations of England. In the Oxford and Kimmeridge Clays water-worn trunks and branches of large pine-trees are often met with. An interesting deposit of these remains was brought to light by my youngest son (Mr. Reginald Mantell), when constructing the branch line of railway from the Great Western to Trowbridge, in Wilts. In the progress of the work, extensive sections were cut through the Oxford Clay, and laid bare a large quantity of drifted wood, much of which was not FOSSIL CONIFEROUS WOOD. Coniferous Wood in the Chalk formation.—The arenaceous limestones of the Greensand of Kent and Sussex abound, in some localities, in water-worn masses of coniferous wood, which are often perforated by boring mollusks, as Teredo, Fistulana, GastrochÆna, &c. In the Iguanodon quarry of Kentish rag, near Maidstone, large quantities of these remains occur, and Mr. Bensted has collected several cones belonging to different kinds of conifers; one of these appears to be a species of Abies, or Fir: Near Willingdon, in Sussex (Geol. S. E. p. 172), a bed of sand, immediately beneath the Galt, contains a layer of water-worn fragments of stems and branches, of small size; they are generally perforated by GastrochÆnce, and the cavities formed by these depredators are filled with particles of green chlorite sand. The structure of this wood is represented In this deposit of coniferous wood, two or more fruits apparently referable to ZamiÆ have been discovered; one specimen, five and a half inches long, and of an elongated cylindrical form, covered with rhomboidal eminences, I have figured and described as Zamites Sussexiensis. Lign. 58. Fragment of Coniferous Wood in Flint. From a wall in Lewes Priory, The White Chalk of England has afforded but few traces of plants of this family. Fragments of coniferous wood are, however, occasionally found in the state of carbonaceous, or reddish brown friable masses, and when this substance is removed, the surface of the chalk is seen to be marked with impressions of ligneous fibres; sometimes the surface is Occasionally silicified fragments of wood are found imbedded in flint. I have an interesting specimen of this kind obtained from a wall in Lewes Priory ( WOOD IN FLINT. Tertiary Coniferous Wood.—The Tertiary formations in some localities abound in coniferous plants and trees, which, in the Paris basin, are associated with bones of mammalia; several species of pine (Pinus) and of yew (Taxus) from those deposits are described by M. Brongniart. I have collected fossils of this kind from the London Clay of the Isle of Sheppey, Bracklesham Bay, and Bognor in Sussex, and Alum Bay, in the Isle of Wight; and from the plastic clay at Newhaven. Fossil Foliage and Fruit of Conifers.—From this digression on the pine-forests and drift-wood of the secondary formations, we return to the examination of the foliage and fruits of this order of vegetables that are preserved in the mineral kingdom. Araucaria peregrina (Lindley and Hutton). Lign. 59.
Pinites; a name applied to those fossil leaves and fruits which agree in their general character with the recent genus Pinus; upwards of thirty species are known. Pinites Fittoni. Geol. Isle of Wight; 2d edit, p. 457.—Several cones with the above characters have been found in the Wealden formation. A cone figured and described by Dr Fitton, is remarkable for a double prominence on each scale: It was supposed to resemble the fruit of Dammara, but the strobilus of the latter is like that of the Cedar of Lebanon, in which the edges of the scales are thin. The Wealden fossil appears to be a genuine pine, and may be distinguished by the name of its discoverer, Pinites Fittoni; a small figure of the only known specimen is given, Wond. p. 399, fig. 4. I have collected from the Wealden strata of the Isle of Wight three or four small cones, which resemble those of a species of Araucaria; they are ovate, imbricated, with acuminated scales, which are recurved at the apex. The fossils figured in Wond. p. 399, figs. 2 and 3, are, I believe, water-worn specimens of the same species. Pinus.—Fruit-catkins ovate, roundish, or cylindrical closely set with thick two-flowered scales; forming an imbricated cone, composed of numerous ligneous angular, or flat, rigid scales, having attached to the inside of each two seeds crowned with a thin membraneous, falcate, oblong, or roundish wing; the scales are composed of a thick woody substance, forming an angular surface, with a recurved point. The Pines are evergreen trees, with from two to five narrow, angular leaves springing from each sheath. Cotyledons four to twelve. Abies.—Cones with thin flat scales, which are more membranous at the extremities than in Pines: the leaves are emarginate, short solitary, needle-shaped, angular or flat. WALCHIA. Walchia. Lign. 60. Walchia hypnoides; 1/3 nat. Permian, LodÈve. Part of a bough with six of the branches bearing terminal cones. Abietites.—To the Abies, or Fir, several cones found in the Wealden deposits of Sussex and Hants closely approximate in the form and structure of their scales. The most remarkable is the very elongated coniferous fruit, first discovered by me in the Wealden at Brook Point, and described and figured in my Geology of the Isle of Wight (2d edit. p. 452), under the name of Abietites Dunkeri, in honour of I have been so fortunate as to collect from thirty to forty specimens of these fruits of the conifers of the country of the Iguanodon, associated with trunks and branches, and imperfect vestiges of single lanceolate leaves. Lign. 61. Abietites Dunkeri. Wealden; Isle of Wight; 1/3 nat. Fir-cone, showing the imbricated scales, and many bracteÆ. ABIETITES DUNKERI. Abietites Dunkeri. These cones are generally found more or less pyritified, and are extremely beautiful objects when first collected; but like the fruits from the Isle of Sheppey, similarly mineralized, often decompose, in spite of every precaution, after exposure to the air but for a few weeks. A small sub-ovate fir-cone found with coniferous wood in Fossil Cypresses.—The tribe of conifers called Cupressus or Cypress, (distinguished from the firs and pines by the leaves being mere scales, and the cones consisting of small wooded peltate bracteÆ, and by other botanical characters,) including the Juniper and Arbor-vitÆ, appears to have flourished during the whole of the secondary epochs; for fossil leaves and stems referable to this family, but whose generic affinities cannot be determined with precision, have been found in the Trias, Lias, Oolite, and Wealden deposits. Lign. 62. Thuites Kurrianus nat. Wealden. Hastings. Thuites Kurrianus. Voltzia. TAXITES. NŒGGERATHIA. FOSSIL RESINS. Taxites.—Some branches found in the Stonesfield slate, and bearing a general resemblance to twigs of Yew (Taxus), are described under the above name, but their analogies are doubtful. (See ante, p. 145.) Noeggerathia. Fossil Resins.—Amber.—The resinous secretions of Conifers are occasionally found in a fossil state. When the tunnel was carried through Highgate Hill, in 1811, concretionary lumps of a brittle substance were discovered, which proved, upon analysis, to be the resin of a coniferous tree The pollen of pines or firs occurs in a tertiary deposit at Egra, in Bohemia; this bed is entirely composed of pollen and the frustules of many kinds of diatomaceÆ. AMBER. FOSSIL PALMS. Amber, so remarkable for its electrical properties, and so largely used for ornamental purposes, is a fossil resin, the product of an extinct species of pine (Pinus succinifer), which, though nearly allied to Pinus abies, and P. picea, is essentially distinct. The Amber in the European markets is principally collected from the shores of the Baltic, between Memel and Konigsberg, being washed out of submerged beds of lignite, and thrown up on the strand by the waves. Amber is occasionally found on the eastern and northern shores of England. The forests of Amber-pines appear to have been situated in the south-eastern part of what is now the bed of the Baltic, in about 55° north latitude, and 37° to 38° east longitude, and were probably destroyed at the commencement of the Drift period. Insects, spiders, small crustaceans, leaves, and fragments of vegetable tissue, are often imbedded in amber; and a few hairs and feathers of mammalia and birds have been detected. These organic bodies must have become immersed in this substance when it exuded from the trees in a viscid state, for they are often preserved as fresh and beautiful as if recently embalmed in the liquid resin. Upwards of 800 species of insects have been discovered, chiefly referable to Aptera, Diptera, Neuroptera, Coleoptera, Libellula, &c.: by far the greater number belong to extinct forms. The vegetable remains comprise four species of pine, and Fossil Palms (Palmacites).—Reserving an account of the fossil plants belonging to the other grand division of Dicotyledons, the Angiosperms (ante, p. 61.), for the last section of the present chapter, I proceed to notice the most important family of the Endogens, or Monocotyledons, whose remains occur abundantly in many tertiary deposits—the Palms. The Palms are, for the most part, lofty trees, having a single cylindrical stem, which, like that of the arborescent ferns, rises to a great height, and is crowned with a canopy of foliage. The trunks are solid, most dense on the outer part, and in some species (as the Cane-palms) are coated with a thin siliceous epidermis. At a little distance above the surface of the ground, strong, simple, rope-like roots are sent off from the stem, appearing like clusters of stays or braces to support the trunk; and the base of the petrified palm-trees often exhibits vestiges of these organs. The Palm family is divided into upwards of sixty genera, comprising more than a thousand species: the greater number are inhabitants of tropical countries. Stems, with the external surface and internal structure preserved, and the foliage, and fruit, of several kinds of Palms, have been found in a fossil state, and chiefly in the Tertiary formations. Examples of the large silicified palm-stems from the West India Islands, where they occur imbedded with corals petrified in the same manner, are to be seen in the British Museum, The Palmacites carbonigenus of Corda, and other supposed palm-trees of the Coal formation, are regarded by the same eminent botanist as essentially differing in structure from this family, and belonging to an extinct tribe of exogens. That a large proportion of the exogenous stems found in FOSSIL PALM LEAVES. Stems, leaves, and fruits of Palms have been discovered in the Paris basin, by M. Ad. Brongniart (Bd. pl. lxiv. p. 515); and silicified trunks in many other places on the Continent; but no fossils of this kind surpass in beauty and interest those which are found in the West Indies. A slice of a silicified stem from Antigua is represented, as seen by reflected light, in Plate V. fig. 1; it admirably displays bundles of vessels imbedded in cellular tissue. Silicified stems of monocotyledons, related to the Palms, are very widely distributed, and have been collected among mammalian remains in Ava, and in the Sub-Himalaya mountains. Fossil Palm-leaves.—The pinnated and fan-shaped leaves of the Palms are so peculiar as to be easily recognized in a fossil state. Though many specimens have been found in the tertiary strata of the Continent, but two or three examples have been met with in England. The first discovered British specimen is in my cabinet, and was obtained by Mr. Fowlstone, of Ryde, from the fresh-water limestone of Whitecliff Bay, in the Isle of Wight. It is thirteen inches in length, and eleven in width: fresh-water shells and plants are imbedded with it. It is figured in Geol. I. of Wight, 2d edit. p. 431. This species (Palmacites Lamanonis) occurs also at Aix in Provence, in great perfection, associated with Insects, Fishes, fresh-water shells, &c. (Wond. p. 260. Petrif. p. 62). Twelve species of palm-leaves are enumerated by M. Unger, from the Tertiary deposits of the Continent. One species has been found in the Chalk formation of Silesia; the most ancient strata in which the remains of undoubted palms have as yet been observed. The fossil palm-leaves of the pinnated form are named Phoenicites, Fossil Fruits of Palms.—Although certain fruits found in the coal-measures have been referred to the palm-tribe by M. Unger, Dr. Lindley, and other botanists, M. Brongniart is of opinion that no such identification can be established; the same remark applies to the Carpolithes from the Oolite; in fine, the Tertiary deposits have alone yielded fruits that can be unquestionably referred to plants of this order. The most productive British locality of fossil fruits of Palms, and of many other vegetables, is the Island of Sheppey; and I purpose describing in this place, not only the remains of this family, but also of the other plants associated with them. Fossil Fruits of the Isle of Sheppey.—This little island, which is situated in the mouth of the Thames, is entirely composed of the London Clay, with bands of septaria. On the north, there is a range of cliffs, about two hundred feet high, which is being continually undermined by the waves, and large masses of the clay are thrown down, and innumerable fruits, seeds, branches and stems of trees, and other fossils, are exposed on the strand at low-water. The vegetables are strongly impregnated with iron pyrites, and as this mineral speedily decomposes when exposed to the atmosphere, the choicest examples often fall to pieces, Mr. Parkinson has given admirable figures of several of the Sheppey fruits, particularly of the large palm-like nuts, called "petrified figs" (Org. Rem. vol. i. pl. vi. vii. Pict. Atlas, pl. vi. vii.) M. Ad. Brongniart has named several in his Prodrome; but without figures the descriptions are useless to the student. Mr. Bowerbank has published two numbers of a work entitled, "History of the Fossil Fruits of the London Clay," with seventeen plates; from which I have selected a few subjects for illustration. The fruits described are the following:
Lign. 63. Fossil Fruits from the Isle of Sheppey. London Clay.
Lign. 64. Fossil Fruits from the Isle of Sheppey. London Clay.
Nipadites. Mr. Bowerbank has shown that they are nearly related to the fruit of the Nipa, or Molucca-Palm, a tree which abounds in Bengal, and in the Molucca and Philippine Islands. The NipÆ are low, shrub-like plants, having the general aspect of palms; they grow in marshy tracts, at the mouths of great rivers, particularly where the waters are brackish. They are allied to the Cocoa-nut tribe, on the one hand, and to the Pandanus, or Screw-pine, on the other. The Nipadites, according to Mr. Bowerbank, have the epicarp and endocarp thin and membranous, and the sarcocarp thick and pulpy, and composed of cellular tissue, through which run numerous bundles of vessels. Nearly in the centre of the pericarp is situated a large seed which, when broken, is more or less hollow. This seed consists of regular layers of cells, radiating from a spot situated near the middle, and apparently inclosing a central embryo. The same author remarks, that "if the habits of the plants to which the fossil fruits belonged were similar to those of the recent Nipa, it will account for their abundance in the London Clay in the Isle of Sheppey; which formation, from the great variety of stems and branches, mixed up with star-fishes, shells of mollusks, and bones of fishes, crustaceans, and reptiles of numerous marine and fresh-water genera, is strikingly characteristic of the delta of a river, which probably flowed from near the Equator towards the spot where these interesting relics are deposited." The fact that the Carpolithes of this kind occur in great perfection in the Eocene strata of Belgium, and were figured and described, nearly seventy years since, in Burton's "Oryctographie de Bruxelles," as petrified cocoa-nuts; the uncompressed state in which these fossils occur makes the resemblance to the recent fruit more striking than in the flattened pyritous specimens from the clay of Sheppey. NIPADITES OF BELGIUM. The Nipadites of Brussels have recently been brought under the more immediate notice of English geologists, in a memoir "On the Tertiary Strata of Belgium and French Flanders," by Sir Charles Lyell, in which several specimens are figured and described. Of the thirteen species of Nipadites enumerated by Mr. Bowerbank, some of which are, however, only accidental varieties, four have been identified among those obtained from Schaerbeek: two of them belong to but one species—the FOSSIL PANDANUS. Fossil Fruit of Pandanus. (Popocarya. Bd. pl. lxii. p. 503.)—The PandanaceÆ are monocotyledonous trees, named Screw Pines from the spiral insertion of their long, rigid, sword-like leaves, along the stem; they are natives of hot climates, and abound in the groups of islands in the Pacific; being generally the first important vegetable tenants of the newly-formed Atols or coral-islands. As in the palms, the stem is supported near the base by long side-roots, which enable these trees to maintain an erect position, and flourish on the newly-elevated coral-reefs, where but little soil has accumulated. The existence of this tribe of plants during the secondary ages is known only by a single example of a fossil fruit, Lign. 65. Fossil Wood with Teredines; nat. London Clay, Regent's Park.
This carpolithe, (for a detailed account and figures see Bd. p. 504, pl. lxiii.) is of the size of a large orange; the surface is covered with a stellated epicarpium, composed of hexagonal tubercles forming the summits of cells which occupy the entire circumference of the fruit. Each cell contains a single seed, usually hexagonal, resembling a small grain of rice, and is supported by a foot-stalk, formed of dense fibres; a character exhibited only by the seed-vessels of Pandanus. The fossil fruit differs from that of the recent Screw-pines in the seeds being neither inclosed in a hard nut, nor collected into drupes, but dispersed uniformly over the entire mass; this forms the essential generic distinction between them. Dr. Buckland has named this unique carpolithe Podocarya. (Bd. p. 505.) Wood perforated by TeredinÆ. In the fossil, 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, 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 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. Lign. 66. Fossil Fresh-water Plants. Eocene, Paris.
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. Fossil NympheÆ. 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 ( 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 Lign. 67. Fossil Nuts, and Flower.
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. 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 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 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; Lign. 68. Imprints of Dicotyledonous Leaves in Gypseous Marl. Tertiary. Stradella, near Pavia.
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 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, 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 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." Many of the trunks are scattered over the surface, among rolled and angular fragments of dark grit, and pebbles of jasper, 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 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, The epidermis of the leaves often occurs in a carbonized state, and is recognizable by its microscopic structure. 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. 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, RETROSPECT OF FOSSIL BOTANY. 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 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 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.
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 The following analysis of the flora of the Carboniferous epoch, by M. Brongniart, will exemplify these remarks. ANALYSIS OF THE CARBONIFEROUS FLORA
Thus out of five hundred species, 352 are Cryptogamia; and with the exception of six, belong to the Acrogens.
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; 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 ON COLLECTING BRITISH FOSSIL VEGETABLES. 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. 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, BRITISH LOCALITIES OF FOSSIL VEGETABLES. BRITISH LOCALITIES OF FOSSIL VEGETABLES.
The above list must, of course, be considered as merely suggestive: many other localities are mentioned in the previous notices of the fossil genera. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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