Proofs of Design in the Structure of
GENERAL HISTORY OF FOSSIL VEGETABLES.
THE history of Fossil Vegetables has a twofold claim upon our consideration, in relation to the object of our present enquiry. The first regards the influence exerted on the actual condition of Mankind, by the fossil carbonaceous remains of Plants, which clothed the former surface of the Earth, and has been briefly considered in a former chapter; (Chap. VII. P. 63.) the second directs our attention to the history and structure of the ancient members of the vegetable kingdom.
It appears that nearly at the same points in the progress of stratification, where the most striking changes take place in the remains of Animal life, there are found also concurrent changes in the character of fossil Vegetables.
A large and new field of investigation is thus laid open to our enquiry, wherein we may compare the laws which regulated the varying
[451 SEA WEEDS.] systems of vegetation, on the earlier surfaces of our earth, with those which actually prevail. Should it result from this enquiry, that the families which make up our fossil Flora were formed on principles, either identical with those that regulate the development of existing plants, or so closely allied to them, as to form connected parts of one and the same great system of laws, for the universal regulation of organic life, we shall add another link to the chain of arguments which we extract from the interior of the Earth, in proof of the Unity of the Intelligence and of the Power, which have presided over the entire construction of the material world.
We have seen that the first remains of Animal life yet noticed are marine, and as the existence of any kind of animals implies the prior, or at least the contemporaneous existence of Vegetables, to afford them sustenance, the presence of sea weeds in strata coeval with these most ancient animals, and their continuance onwards throughout all formations of marine origin, is a matter of a priori probability, which has been confirmed by the results of actual observation. M. Adolphe Brongniart, in his admirable History of Fossil Vegetables,* has shewn, that the existing submarine vegetation seems to admit of three great divisions which characterize, to a certain degree, the Plants of the frigid, temperate, amid torrid zones; and
[452 DISTRIBUTION OF] that an analogous distribution of the fossil submerged Algæ appears to have placed in the lowest and most ancient formations, genera allied to those which now grow in regions of the greatest heat, whilst the forms of marine vegetation that succeed each other in the Secondary and Tertiary periods, seem to approximate nearer to those of our present climate, as they are respectively enclosed in strata of more recent formation.*
If we take a general review of the remains of terrestrial Vegetables, that are distributed through the three great periods of geological history, we find a similar division of them into groups, each respectively indicating the same successive
* See Ad. Brongniart's Hist. de Vég. Foss. 1 Liv. p. 47. — Dr. Harlan in the Journal of the Academy of Nat. Sc. of Philadelphia, 1831, and Mr. R. G. Taylor in Loudon's Mag. Nat. Hist. Jan. 1834, have published accounts of numerous deposits of fucoids, as occurring in repeated thin layers among the Transition strata of N. America, and extending over a long tract on the E. flank of the Alleghany chain. The most abundant of these is the Fucoides Alleghaniensis of Dr. Harlan. Mr. R. G. Taylor has found extensive deposits of fossil Fuci in the Grauwacke of central Pennsylvania; in one place seven courses of Plants are laid bare in the thickness of four feet, in another, one hundred courses within a thickness of twenty feet. (Jameson's Journal, July, 1835, p. 185.) I have also seen Fucoids in great abundance in the Grauwacke-slate of the Maritime Alps, in many parts of the new road between Nice and Genoa. I once found small Fucoids dispersed abundantly through shale of the Lias formation, from a well at Cheltenham. The Fucoides granulatus occurs in Lias at Lyme Regis, and at Boll in Wurtemberg; and F. Targionii in the Upper Green-sand near Bignor in Sussex.
[453 FOSSIL VEGETABLES. diminutions of Temperature upon the Land, which have been inferred from the remains of the vegetation of the Sea. Thus, in strata of the Transition series, we have an association of a few existing families of Endogenous Plants,* chiefly Ferns and Equisetaceæ, with extinct families both Endogenous and Exogenous, which some modern botanists have considered to indicate a Climate hotter than that of the Tropics of the present day. In the Secondary formations, the species of these most early families become much less numerous, and many of their genera, and even of the families themselves entirely cease; and a large increase takes place in two families, that comprehend many existing forms of vegetables, and are rare in the Coal formation, viz. Cycadeœ and Coniferœ. The united characters of the groups associated in this series, indicate a Climate, whose temperature was nearly similar to that which prevails within the present Tropics.
In the Tertiary deposits, the greater number of the families of the first series, and many of those of the second, disappear; and a more complicated dicotyledonous Vegetation takes place of
* Endogenous Plants are those, the growth of whose stems takes place by addition from within. Exogenous are those in which the growth takes place by addition from without.
Monocotyledonous Plants are those, the embryo of whose seed is made up of one cotyledon or lobe, like the seed of a Lily or an Onion. Dicotyledonous Plants are those, the embryo of
[454 VEGETABLE ORIGIN] the simpler forms which predominated through the two preceding periods. Smaller Equisetaceæ also succeed to the gigantic Calamites; Ferns are reduced in size and number to the scanty proportions they bear on the southern verge of our temperate climates; the presence of Palms attests the absence of any severe degree of cold, and the general character marks a Climate nearly approaching to that of the Mediterranean.
We owe to the labours of Schlotheim, Sternberg and Ad. Brongniart the foundation of such a systematic arrangement of fossil plants, as enables us to enter, by means of the analogies of recent plants, into the difficult question of the Ancient Vegetation of the Earth, during those periods when the strata were under the process of formation.
Few persons are aware of the nature of the evidence, upon which we have at length arrived at a certain and satisfactory conclusion, respecting the long disputed question as to the vegetable origin of Coal. It is not unfrequent to find among
* whose seed is made up of two lobes, as in the Bean and Coffee seed. The stems of Monocotyledonous Plants are all Endogenous, i. e. increase from within by the addition of bundles of vessels set in cellular substance, and enlarge their bulk by addition from the centre outwards, e. g. Palms, Canes, and Liliaceous plants. The stems of Dicotyledonous Plants are all Exogenous, i. e. increase externally by the addition of concentric layers from without; these form the rings, which mark the amount of annual growth in the Oak and other forest trees in our climate.
[455 OF COAL.] the cinders beneath our grates, traces of fossil
plants whose cavities, having been filled with silt, at the time of their deposition in the vegetable mass, that gave origin to the Coal, have left the impression of their forms upon clay and sand enclosed within them, sharp as those received by a cast from the interior of a mould.
A still more decisive proof of the vegetable origins even of the most perfect bituminous Coal has recently been discovered by Mr. Hutton; he has ascertained that if any of the three varieties of Coal found near Newcastle be cut into very thin slices and submitted to the microscope, more or less of vegetable structure can be recognized.*
* " In these varieties of coal," says Mr. Hutton, " even in samples taken indiscriminately, more or less of Vegetable Texture could always be discovered, thus affording the fullest evidence, if any such proof were wanting, of the Vegetable Origin of Coal.
"Each of these three kinds of coal, besides the fine distinct reticulation of the original vegetable texture, exhibits other cells, which are filled with a light wine-yelIow-coloured matter, apparently of a bituminous nature, and which is so volatile as to be entirely expelled by heat, before any change is effected in the other constituents of the coal. The number and appearance of these cells vary with each variety of coal. In caking coal, the cells are comparatively few, and are highly elongated. In the finest portions of this coal, where the crystalline structure, as indicated by the rhomboidal form of its fragments, is most developed, the cells are completely obliterated.
"The slate-coal, contains two kinds of cells, both of which are filled with yellow bituminous matter. One kind is that already noticed in caking coal ; while the other kind of cells constitutes groups of smaller cells, of an elongated circular figure
[466 STATE OF FOSSIL PLANTS] We shall further illustrate this point, by a brief description of the manner in which the remains of vegetables are disposed in the Carboniferous strata of two important Coal fields, namely, those of Newcastle in the north of England, and of Swina in Bohemia, on the N. W. of Prague.
The Newcastle Coal field is at the present time supplying rich materials to the Fossil Flora of Great Britain, now under publication by Professor Lindley and Mr. Hutton. The plants of the Bohemian Coal field laid the foundation of Count Steinberg's Flore du monde primitif, the publication of which commenced at Leipsic and Prague in 1820.
" In those varieties which go under the name of Cannel, Parrot, and Splent Coal, the crystalline structure, so conspicuous in fine caking coal, is wholly wanting; the first kind of cells are rarely seen, and the whole surface displays an almost uniform series of the second class of cells, filled with bituminous matter, and separated from each other by thin fibrous divisions. Mr. Hutton considers it highly probable that these cells are derived from the reticular texture of the parent plant, rounded and confused by the enormous pressure, to which the vegetable matter has been subject."
The author next states that though the crystalline and uncrystalline, or, in other terms, perfectly and iinperfectly developed varieties of coal generally occur in distinct strata, yet it is easy to find specimens which in the compass of a single square inch, contain both varieties. From this fact, as also from the exact similarity of position which they occupy in the mine, the differences in different varieties of coal are ascribed to original difference in the plants from which they were derived. Proceedings of Geological Society. Lond. and Edin. Phil. Mag. 3rd Series Vol. 2. p. 302. April, 1833.
[457 IN NEWCASTLE COAL PITS.] Lindley and Hutton state (Fossil Flora, Vol. l. page 16) that "It is the beds of shale, or argillaceous schistus, which afford the most abundant supply of these curious relics of a former World; the fine particles of which they are composed having sealed up and retained in wonderful perfection and beauty, the most delicate forms of the vegetable organic structure. Where shale forms the roof of the workable seams of coal, as it generally does, we have the most abundant display of fossils, and this, not perhaps arising so much from any peculiarity in these beds, as from their being more extensively known and examined than any others. The principal deposit is not in immediate contact with the coal, but about from twelve to twenty inches above it; and such is the immense profusion in this situation, that they are not unfrequently the cause of very serious accidents, by breaking the adhesion of the shale bed, and causing it to separate and fall, when by the operation of the miner the coal which supported it is removed. After an extensive fall of this kind has taken place, it is a curious sight to see the roof of the mine covered with these vegetable forms, some of them of great beauty and delicacy; and the observer cannot fail to be struck with the extraordinary confusion, and the numerous marks of strong mechanical action exhibited by their broken and disjointed remains."
[458 COAL MINE IN BOHEMlA.] A similar abundance of distinctly preserved vegetable remains, occurs throughout the other Coal fields of Great Britain. But the finest example I have ever witnessed, is that of the coal mines of Bohemia just mentioned. The most elaborate imitations of living foliage upon the painted ceilings of Italian palaces, bear no comparison with the beauteous profusion of extinct vegetable forms, with which the galleries of these instructive coal mines are overhung. Tlie roof is covered as with a canopy of gorgeous tapestry, enriched with festoons of most graceful foliage, flung in wild, irregular profusion over every portion of its surface. The effect is heightened by the contrast of the coal-black colour of these vegetables, with the light ground work of the rock to which they are attached. The spectator feels himself transported, as if by enchantment, into the forests of another world; he beholds Trees, of forms and characters now unknown upon the surface of the earth, presented to his senses almost in the beauty and vigour of their primeval life; their scaly stems, and bending branches, with their delicate apparatus of foliage, are all spread forth before him; little impaired by the lapse of countless Ages, and bearing faithful records of extinct systems of vegetation, which began and terminated in times of which these relics are the infallible Historians.
Such are the grand natural Herbaria wherein
[459 PLANTS IN THE COAL FORMATION.] these most ancient remains of the vegetable kingdom are preserved, in a state of integrity, little short of their living perfection, under conditions of our Planet which exist no more.
VEGETABLES IN STRATA OF THE TRANSITION SERIES.*
THE remains of plants of the Transition period are most abundant in that newest portion of the deposits of this era, which constitutes the Coal Formation, and afford decisive evidence as to the condition of the vegetable kingdom at this early epoch in the history of Organic Life. The Nature of our Evidence will be best illustrated, by selecting a few examples of the many genera of fossil plants that are preserved in the Strata of the Carboniferous Order, beginning with those which are common both to the ancient and existing states of Vegetable Life.
Among existing vegetables, the Equisetaceæ are well known in this climate in the common Horse-tail of our swamps and ditches. The extent of this family reaches from Lapland to the
* See Pl. l. Figs. 1, to 13.
See Pl. l. Fig. 2.
[460 CALAMITES.] Torrid Zone, its species are most abundant in the temperate zone, decrease in size and num ber as we approach the regions of cold, and arrive at their greatest magnitude in the warm and humid regions of the Tropics, where their numbers are few.
M. Ad. Brongniart* has divided fossil Equisetaceæ into two Genera; the one exhibits the characters of living Equiseta, and is of rare occurrence in a fossil state; the other is very abundant, and presents forms that differ materially from them, and often attain a size unknown among living Equisetaceæ; these have been arranged under the distinct genus Calamites, they abound universally in the most ancient Coal formation, occur but sparingly in the lower strata of the Secondary series, and are entirely wanting in the Tertiary formations, and also on the actual surface of the earth.
The same increased development of size, which in recent Equisetaceæ accompanies their geographical
* Histoire des Végétaux Fossiles, 2nd Livraison.
Calamites are characterized by large and simple cylindrical stems, articulated at intervals, but either without sheaths, or presenting them under forms unknown among existing Equiseta; they have sometimes marks of verticillated Branches around their articulations, the leaves also are without joints. But the most obvious feature wherein they differ from Equiseta, is their bulk and height, sometimes exceeding six or seven inches in diameter, whilst the diameter of a living Equisetum rarely exceeds half an inch. A Calamite fourteen inches in diameter has lately been placed in the Museum at Leeds.
[461 FERNS.] approximation to the Equator, is found in the fossil species of this order to accompany the higher degrees of Antiquity of the strata in which they occur; and this without respect to the latitude, in which these formations may be placed. M. Ad. Brongniart (Prodrome, p. 167) enumerates twelve species of Calamites and two of Equiseta in his list of plants found in strata of the Carboniferous order.
The family of Ferns, both in the living and fossil Flora, is the most numerous of vascular Cryptogamous plants. Our knowledge of the geographical distribution of existing Ferns, as connected with Temperature, enables us in some degree to appreciate the information to be derived from the character of fossil Ferns, in regard to the early conditions and Climate of our globe.
* See Pl. l. No. 6.7. 8. 37. 38. 39.
Ferns are distinguished from all other vegetables by the peculiar division and distribution of the veins of the leaves; and in arborescent species, by their cylindrical sterns without branches, and by the regular disposition and shape of the scars left upon the stem, at the point from which the Petioles, or leaf stalks, have fallen off. Upon the former of these characters M. Ad. Brongniart has chiefly founded his classification of fossil Ferns, it being impossible to apply to them the system adopted in the arrangement of living Genera, founded on the varied disposition of the fractification, which is rarely preserved in a fossil state.
[462 DISTRIBUTION OF RECENT FERNS.] The total known number of existing species of Ferns is about 1.500. These admit of a threefold geographical distribution:
l. Those of the temperate and frigid zone of the northern hemisphere, containing 144 species.If we compare the amount of Ferns with the united numbers of other tribes of plants, we may form some idea of the relative importance of this family in the vegetation of the district, or period to which we apply such comparison. Thus, in the entire number of known species of plants now existing on the globe, we have 1600 Ferns and 45,000 Phanerogamiæ, being in the proportion of 1 to 30. In Europe this proportion varies from 1:35 to l:80, and may average 1:60. Between the Tropics, Humboldt estimates the number in Equinoxial America at 1:36, and Mr. Brown gives 1:20 as the proportion in those parts of intertropical Continents which are most favourable* to Ferns.
2. Those of the southern temperate zone, including the Cape of Good Hope, parts of South America, and the extra-tropical part of New Holland, and New Zealand, 140 species.
3. Those which grow within 30 or 35 degrees on each side of the Equator, 1200 species.
Mr. Brown (Appendix to Tuckey's Congo Expedition) states that the circumstances most
* Botany of Congo, p. 42.
[463 ARBORESCENT FERNS.] favourable to the growth of Ferns are humidity, shade, and beat. These circumstances are most frequently combined in the highest degree in small and lofty tropical islands, where the air is charged with humidity, which it is continually depositing on the mountains, and thereby imparting freshness to the soil. Thus in Jamaica Ferns are to the Phanerogamiæ nearly in the proportion of 1 to 10; in New Zealand as 1 to 6; in Taiti as 1 to 4, in Norfolk Island as 1 to 3; in St. Helena as 1 to 2; in Tristan d'Acunha (extra-tropical) as 2 to 3. Ferns are also the most abundant Plants in the Islands of the Indian Archipelago.
It appears still further, that not only are certain Genera and Tribes of Ferns peculiar to certain climates, but that the enlarged size of the arborescent species depends in a great degree on Temperature, since Arborescent Ferns are now found chiefly within, or near the limit of the Tropics.*
From the above considerations as to the characters and distribution of living Ferns, M. Ad. Brougniart has applied himself with much ingenuity, to illustrate the varying condition and climate of our Globe, during the successive periods of geologcal formations. Finding that the fossil
* The few exceptions to this rule appear to be confined to the Southern hemisphere, and one species is found in New Zealand as far south s lat. 46°. See Brown in Appendix to Flinders's Voyage.
[464 DISTRIBUTION OF FOSSIL FERNS.] remains of Ferns decrease continually in number, as we ascend from the most ancient to the most recent strata, he founds upon this fact an important conjecture, with respect to the successive diminutions of temperature, and changes of climate, which the earth has undergone. Thus in the great Coal formation there are about 120 known species of Ferns, forming almost one half of the entire known Flora of this formation; these species represent but a small number of the forms which occur among living Ferns, and nearly all belong to the Tribe of Polypodiaceæ, in which Tribe we find the greater number of existing arborescent species. Fragments of the stems of arborescent Ferns occur occasionally in the same formation. M. Brongniart considers these circumstances as indicating a vegetation, analogous to that of the Islands in the equinoctial regions of the present Earth; and infers that the same conditions of Heat and Humidity which favour the existing vegetation of these islands, prevailed in still greater degree during the
* In plate 1, figs. 7, and 37, represent two of the graceful forms of arborescent Ferns which adorn our modern tropics, where they attain the height of forty and fifty feet.
An arborescent Fern forty-five feet high (Alsophila brunoniana), from Silhet in Bengal, may be seen in the staircase of the British Museum. The stems of these Ferns are distinguished from those of all arborescent Monocotyledonous plants, by the peculiar form and disposition of the scars, from which the Petioles
[465 DISTRIBUTION OF FOSSIL FERNS.] formation of the Carboniferous strata of the Transition Series.
In strata of the Secondary Series, the absolute and relative numbers of species of Ferns considerably diminishes, forming scarcely one third of the known Flora of these midway periods of geological history. (See Pl. 1 . Figs. 37. 38. 39.)
In the Tertiary Strata, Ferns appear to bear to other vegetables nearly the same proportion as in the temperate regions of the present Earth.
or leaf stalks have fallen off. In Palms and other arborescent Monocotyledons, the leaves, or Petioles, embrace the stem and leave broad transverse scars, or rings, whose longer diameter is horizontal. In the case of Ferns alone, with the single exception of Angiopteris, the scars are either elliptic or rhomboidal, and have their longer diameter vertical.
M. Ad. Brongniart (Hist. des Veg. Foss . p. 261, Pl. 79. 80.) has described and figured the leaf and stem of an arborescent fern (Anomopteris, Mougeottii) from the variegated sand-stone of Heilegenberg in the Vosges . Beautiful leaves of this species, with their capsules of fructification sometimes adhering to the pinnules, abound in the New red sand-stone formation of this district.
M. Cotta has published an interesting Work on fossil Remains of arborescent ferns, which occur abundantly in the New red sand-stone of Saxony near Chemnitz. (Dendrolithen. Dresden and Leipsig, l832.) These consist chiefly of sections of the Trunks of many extinct species, sufficiently allied in structure to that of existing arborescent Ferns, to leave little doubt that they are the rernains of extinct species of arborescent Plants of this family, that grew in Europe at this Period of the Secondary formation.
The genus Lepidodendron comprehends many species of fossil plants, which are of large size, and of very frequent occurrence in the Coal formation. In some points of their structure they have been compared to Coniferæ, but in other respects and in their general appearance, with the exception of their great size, they very much resemble the Lycopodiaceæ, or Club Moss Tribe. (See Pl. l. Figs. 9. 10.). This tribe at the present day, contains no species more than three feet high, but the greater part of them are weak, or creeping plants, while their earliest fossil representatives appear to have attained the dimensions of Forest Trees.
Existing Lycopodiaceæ follow nearly the same law as ferns and
Equisetaceæ, in respect of geographical distribution; being
and most abundant in hot and humid situations within the Tropics,
in small islands. The belief that Lepidodendra were allied to the
* Pl. l. Figs. 11. 12. and Pl. 55, Figs. l.
Prof. Lindley states that the affinities of existing Lycopodiaceæ are intermediate between Ferns and Coniferæ on the one hand, and Ferns and Mosses on the other; They are related to Ferns in the want of sexual apparatus, and in the abundance of annular ducts contained in their axis; to Conifere, in the aspect of the stems of some of the larger kinds; and to Mosses in their whole appearance.
[467 LEPIDODENDRON.] and their size, and abundant occurrence among the fossils of the Coal Formation have led writers on fossil plants to infer that great heat, and moisture, and an insular Position were the conditions, under which the first forms of this family attained that gigantic stature, which they exhibit in deposits of the Transition period; thus corroborating the conclusion they had derived from the Calamites associated with them, as already mentioned.*
Lindley and Hutton state, that Lepidodendra are, after Calamites, the most abundant class of fossils in the Coal formation of the North of England; they are sometimes of enormous size, fragments of stems occurring from twenty to forty-five feet long; in the Jarrow colliery a compressed tree of this class measured four feet two inches in breadth . Thirty-four species of
* The leaves of existing Lycopodiaceæ are simple, and arranged in spiral lines around the stem, and impress on its surface scars of rhomboidal, or lanceolate form, marked with prints of the insertions of vessels. In the fossil Lepidodendra, we find a large and beautiful variety of similar scars, arranged like scales in spiral order, over the entire surface of the sterns. A large division of these are arborescent and dichotomous, and have their branches covered with simple lanceolate leaves. Our figure of Lepidodendron Sternbergii (Pl. 55. Figs. l. 2. 3.) represents all these characters in a single Tree from the Coal mines of Swina in Bohemia.
The form of the scales varies at different parts of the same stem, those nearest the base are elongated in the vertical direction.
[468 LEPIDODENDRON.] Lepidodendron are enumerated in M. Ad. Brongniart's Catalogue of fossil plants of the coal formation.
The internal structure of the Lepidodendron has been shewn to be intermediate between Lycopodiaceæ and Coniferæ,* and the conclusions which Prof. Lindley draws from the intermediate condition of this curious extinct genus of fossil plants, are in perfect accordance with the inferences which we have had occasion to derive from analogous conditions in extinct genera of fossil animals. "To Botanists, this discovery is of very high interest, as it proves that those systematists are right, who contend for the possibility of certain chasms now existing between the gradations of organization, being caused by the extinction of genera, or even of whole orders; the existence of which was necessary to complete the harmony which it is believed originally existed in the structure of all parts of the Vegetable kingdom. By means of Lepidodendron, a better passage is established from Flowering to Flower-less Plants, than by either Equisetum or Cycas, or any other known genus." Lindley and Hutton's Fossil Flora, vol. ii. page 53.
* See annual Report of the Yorkshire Phil. Society for 1832. Witham's Fossil Vegetables, 1833, Pl. 12. 13. and Lindley and Hutton's Fossil Flora. Pl. 98 and 99.
Besides the above plants of the Coal formation which are connected with existing Families or Genera, there occur many others which can be referred to no known type in the vegetable kingdom . We have seen that the Calamites take their place in the existing family of Equisetaceæ; that many fossil Ferns are referrible to living genera of this extensive family; and that Lepidodendra approximate to living Lycopodiaceæ and Coniferæ. Together with these, there occur other groups of Plants unknown in modern vegetation, and of which the duration seems to have been limited to the Epochs of the Transition Period. Among the largest and tallest of these unknown forms of Plants, we find colossal Trunks of many species, which M. Ad. Brongniart has designated by the name of Sigillaria. These are dispersed throughout the sand-stones and shales that accompany the Coal, and can occasionally be detected in the Coal itself, to the substance of which they have largely contributed by their remains. They are sometimes seen in an erect position, where views of the strata are afforded by cliffs on the
* Pl. 56, Figs. l. 2.
[470 ERECT POSITION OF FOSSIL TREES.] sea shore, or by inland sections of quarries, banks of rivers, &c.*
The vertical position of these trunks, however, is only occasional and accidental; they lie inclined at all degrees throughout all the strata of the carboniferous series; but are most frequently prostrate, and parallel to the lines of stratification, and, in this position are usually compressed. When erect, or highly inclined, they retain their natural shape, and their interior is filled with sand or clay, often different from that of the stratum in which their lower parts are fixed, and mixed with small fragments of various other plants. As this foreign matter has thus entirely
* On the coast of Northumberland, at Creswell hall, and Newbiggin, near Morpeth, many stems of Sigillaria may be seen, standing erect at right angles to the planes of alternating strata of shale and sand-stone; they vary from ten to twenty feet in height, and from one to three feet in diameter, and are usually truncated at their upper end; many terminate downwards in a bulb-shaped enlargement, near the commencement of the roots, but no roots remain attached to any of them. Mr. W. G. Tre velyan counted twenty portions of such Trees, within the length of half a mile; all but four or five of these were upright; the bark, which was seen when they were first uncovered, but soon fell off, was about half an inch in thickness, and entirely converted into coal. Mr. Trevelyan observed four varieties of these stems, and engraved a sketch of one of them in 1816, which is copied in Count Steinberg's Tab. 7, Fig. 5.
In September, 1834, I saw in one of the Coal Mines of Earl Fitzwilliam, at Elsecar, near Rotherham, many large Trunks of Sigillaria, in the sides of a gallery by which you walk into the mine, from the outcrop of a bed of Coal about six feet thick. These stems were inclined in all directions, and some of them
[471 INTEflIOR OF TRUNKS.] filled the interior of these trunks, it follows that they must have been without any transverse dissepiments, and hollow throughout, at the time when the sand, and mud, and fragments of other plants found admission to their interior. The bark, which alone remains, and has been converted into coal, probably surrounded an axis composed of soft and perishable pulpy matter, like the fleshy interior of the stems of living Cacteæ; and the decay of this soft internal trunk, whilst the stems were floating in the water, probably made room for the introduction of the sand and clay.
These trunks usually vary from half a foot to three feet in diameter . When perfect, the height
nearly vertical. The interior of those whose inclination exceeded 45° was filled with an indurated mixture of clay and sand; the lower extremity of several rested on the upper surface of the bed of Coal. None had any traces of Roots, nor could any one of them have grown in its present place.
M Alex. Brongniart has engraved a section at St. Etienne, iii which many similar stems are seen in an erect position, in sand-stone of the Coal formation, and infers from this fact that they grew on the spot where they are now found. M. Constant Prevost justly objects to this inference, that, had they grown on the spot, they would all have been rooted in the same stratum, and not have had their bases in different strata. When I visited these quarries in 1826, there were other trunks, more numerous than the upright ones, inclined in various directions.
I have seen but one example, viz, that of Balgray quarry, three miles N. of Glasgow, of erect stumps of large trees fixed by their roots in sand-stone of the coal formation, in which, when soft, they appear to have grown, close to one another. See Lond. and Edin. Phil . Mag. Dec. 1835, p. 487.
[472 SYRINGODENDRON.] of many of them must have been fifty or sixty feet, at least.*
Count Sternberg has applied the name Syringodendron to many species of Sigillaria, from the parallel pipe-shaped flutings that extend from the top to the bottom of their trunks. These trunks are without joints, and many of them attain the size of forest trees. The flutings on their surface bear dot-like, or linear impressions, of various figures, marking the points at which the leaves were inserted into the stem. This fluted portion of the Sigillariæ, formed their external covering, separable like true bark from the soft internal axis, or pulpy trunk; it varied in thickness from an inch to one-eighth of an inch, and is usually converted into pure coal. (See Pl. 56, Fig. 2. a, b, c.)
A fleshy trunk surrounded and strengthened only by such thin bark, must have been incapable of supporting large and heavy branches at its summit. It therefore probably terminated abruptly at the top, like many of the larger species of living Cactus, and the abundant disposition of small leaves around the entire extent of the trunk seems to favour this hypothesis.
* M. Ad. Brongniart found in a coal mine in Westphalia near Essen, the compressed stem of a Sigillaria laid horizontally, to the length of forty feet; it was about twelve inches in diameter at its lower, and six inches at its upper extremity, where it divided into two parts, each four inches in diameter. The lower end was broken off abruptly. Lindley and Hutton's Foss. Flora, vol. i. p. 153.
[473 BARK FLUTED AND SCARRED.] The impressions, or scars, which formed the articulations of leaves on the longitudinal flutings of the trunks of Sigillariæ, are disposed in vertical rows on the centre of each fluting from the top to the bottom of the trunk. Each of these scars marks the place from which a leaf has fallen of, and exhibits usually two apertures, by which bundles of vessels passed through the bark to connect the leaves with the axis of the tree. No leaf has yet been found attached to any of these trunks; we are therefore left entirely to conjecture as to what their nature may have been. This non-occurrence of a single leaf upon any one of the many thousand trunks that have come under observation, leads us to infer that every leaf was separated from its articulation, and that many of them perhaps, like the fleshy interior of the stems, had undergone decomposition, during the interval in which they were floating between their place of growth, and that of their final submersion.
M. Ad. Brongniart enumerates forty-two species of Sigillaria, and considers them to have been nearly allied to arborescent Ferns, with leaves very small in proportion to the size of the stems, and differently disposed from those of any living Ferns. He would refer to these stems many of the numerous fern leaves of unknown species, which resemble those of existing arborescent genera of this family. Lindley and Hutton shew strong reasons for considering that Sigillariæ
[474 EXTINCT GENERA OF CONIFERÆ.] were Dicotyledonous plants, entirely distinct from Ferns, and different from any thing that occurs in the existing system of vegetation.*
Favularia. Megaphyton. Bothrodendron.
The same group of fossil plants to which Lindley and Hutton have referred the genus Sigillaria, contains four other extinct genera, all of which exhibit a similar disposition of scars arranged in vertical rows, and indicating the places at which leaves, or cones, were attached to the trunk. The names of these are Favularia, Megaphyton, Bothrodendron, Ulodendron. Our figures Pl. 56, Figs. 3, 4, 6,6, represent portions of
* "There can be no doubt," say they, (Foss. Flora, vol. i. p. 155) " that as far as external characters go, Sigillaria approached Euphorbiæ and Cacteæ more nearly than any other plants now known, particularly in its soft texture, in its deeply channelled stems, and what is of more consequence in its scars, placed in perpendicular rows between the furrows. It is also well known that both these modern tribes, particularly the latter, arrive even now at great stature; further, it is extremely probable, indeed almost certain, that Sigillaria was a dicotyledonous plant, for no others at the present day have a true separable bark. Nevertheless, in the total absence of all knowledge of the leaves and flowers of these ancient trees, we think it better to place the genus among other species, the affinity of which is at present doubtful."
Pl. 56, Figs. 3. 4. 5. 6. 7.
The genera composing this group are thus described, Foss. Flora, vol. ii. p. 96.
1 . Sigillaria. Stem furrowed. Scars of leaves small, round, much narrower than the ridges of the stem.[475 LEAVES AND CONES IN VERTICAL ROWS.] the trunk and scars of some of these extraordinary Coniferæ.
Among existing vegetables, there are only a few succulent plants which present a similar disposition of leaves, one exactly above another in parallel rows; but in the fossil Flora of the Coal
2. Favularia. Stem furrowed. Scars of leaves small, square, as broad as the ridges of the stem.
3. Megaphyton. Stem not furrowed, dotted. Scars of leaves very large, of a horse shoe figure, much narrower than the ridges.
4. Bothrodendron. Stem not furrowed, covered with dots. Scars of cones, obliquely oval.
5. Ulodendron. Stem not furrowed, covered with rhomboidal marks. Scars of cones circular.
In the three first genera of this group, the scars appear to have given origin to leaves; in the two latter they indicate the insertion of large cones.
In the genus Favularia (Pl. 56, Fig. 7) the trunk was entirely covered with a mass of densely imbricated foliage, the bases of the leaves are nearly square, and the rows of leaves separated by intermediate grooves; whilst in Sigillaria the leaves were placed more loosely, and at various intervals in various species. (Foss. Flora, Pl. 73. 74. 75).
In the genus Megaphyton the stem is not furrowed, and the leaf scars are very large, and resemble the form of horse shoes disposed in two vertical rows, one on each side of the trunk. The minor impressions resembling horse shoes, in the middle of these scars, appear to indicate the figure of the woody system of the leaf stalk. (Foss. Flora, Pl. 116, 117.)
In the genus Bothinodendron (Foss. Flora, Pl. 80, 81) and the genus Ulodendron, (Foss. Flora, Pl. 3. 6.) the stems are marked with deep oval or circular concavities, which appear to have been made by the bases of large cones. These cavities are ranged in two vertical rows, on opposite sides of the trunk, and in some species are nearly five inches in diameter. (Pl. 56. figs. 3. 4. 5. 6.)
[476 STIGMARIA.] formation, nearly one half, out of eighty known
plants, have their leaves growing in parallel series.
The remaining half are Lepidodendra, or extinct
Lindley and Hutton, Foss. Flora, vol. ii. p. 93.)
The recent discoveries of Lindley and Hutton have thrown much light
upon this very extra-ordinary family of extinct fossil plants. Our
Pl. 56, Fig. 8, copied from their engraving of Stigmaria ficoides,
Flora, Pl. 31, Fig. 1) represents one of the best known examples of the
The centre of the plant presents a dome-shaped trunk or stem, three or four feet in diameter, the substance of which was probably yielding and fleshy; both its surfaces were slightly corrugated, and covered with indistinct circular spots. (Pl. 56, Fig. 8. 9.)
From the margin of this dome there proceed many horizontal branches, varying in number in different individuals from nine to fifteen; some of these branches become forked at unequal distances from the dome; they are all broken off
* Pl. 56, Figs. 8. 9. 10. 11.
Seventeen specimens of this kind have been found within the space of 600 square yards, in the shale covering the Bensharn seam of coal at Jarrow Colliery near NewcastIe, at thc depth of 1200 feet.
[477 A GIGANTIC FLOATING PLANT.] short, the longest yet found attached to the stem, was four feet and a half in length. The extent of these branches, when outstretched and perfect, was probably from twenty to thirty feet.* The surface of each branch is covered with spirally disposed tubercles, resembling the papillæ at the base of the spines of Echini. From each tubercle there proceeded a cylindrical and probably succulent leaf; these extended to the length of several feet from all sides of the branches. (Pl. 56, Figs. 10. 11.) The leaves, usually in a compressed state, are found penetrating in all directions into the sand-stone or shale which forms the surrounding matrix; they have been traced to the length of three feet, and have been said to be much longer.
* It appears from sections of a branch of Stigmaria, engraved by Lindley and Hutton, (Foss. Flora, Pl. 166), that its interior was a hollow cylinder composed exclusively of spiral vessels, and containing a thick pith, and that the transverse section exhibits a structure something like that of Coniferæ, but without concentric circles, and with open spaces instead of the muriform tissue of medullary rays. No such structure is known among living plants.
These cylindrical branches are usually depressed on one side, probably the inferior side(PI. 56, Figs. 8. ab. and 10. b.); adjacent to this depression there is found a loose internal eccentric axis, or woody core, (Pl. 56 . Fig. 10. a.) surrounded with vascular fasciculi that communicated with the external tubercles, and resembled the internal axis within the stems of certain species of Cactus.
All these are conditions, which a Plant habitually floating with the leaves distended in every direction, would not cease to maintain, when drifted to the bottom of an Estuary, and there gradually surrounded by sediments of mud and silt.
[478 DOME-SHAPED STEM.] In many of the strata that accompany the coal, fragments of these plants occur in vast abundance; they have been long noticed in the sand stone called Gannister and Crowstone, in the Yorkshire and Derbyshire coal fields, and have been incorrectly considered to be fragments of the stems of Cacti.
The discovery of the dome-shaped centres above described, and the length and forms of the leaves and branches render it highly probable that the Stigmariæ were aquatic plants, trailing in swamps, or floating in still and shallow lakes, like the modern Stratiotes and Isoetes. From such situations they may have been drifted by the same inundations, that transported the Ferns and other land vegetables, with which they are associated in the coal formation. The form of the trunk and branches shews that they could not have risen upwards into the air, they must therefore either have trailed on the ground, or have floated in water.* The Stigmaria was probably dicotyledonous, and its internal structure seems to have borne some analogies to that of the Euphorbiaceæ.
* The place and form of the leaves, supposing them to have grown on all sides of branches suspended horizontally in water, would have been but little changed by being drifted into, and sinking to the bottom of, an estuary or sea, and there becoming surrounded by sediments of mud or sand. This hypothesis seems supported by the observations made at Jarrow, that the extremities of the branches descend from the dome towards the adjacent bed of coal.
[479 PLANTS IN THE COAL FORMATION.]
Besides these Genera which have been enumerated, there are many others whose nature is still more obscure, and of which no traces have been found among existing vegetables, nor in any strata more recent than the Carboniferous series. Many years must elapse before the character of these various remains of the primeval vegetation of the Globe can be fully understood. The plants which have contributed most largely to the highly-interesting and important formation of Coal, are referrible principally to the Genera whose history we have attempted briefly to elucidate: viz. Calamites, Ferns, Lycopodiaceæ, Sigillariæ, and Stigmariaæ. These materials have been collected chiefly from the carboniferous strata of Europe. The same kind of fossil plants are found in the coal mines of N. America, and we have reason to believe that similar remains occur in Coal formations of the same Epoch, under very different Latitudes, and in very distant quarters of the Globe, e. g. in India, and New Holland, in Melville Island, and Baffin's Bay.
The most striking conclusions to which the present state of our knowledge has led, respecting
* Some of the most abundant of these have been classed under the names of Asterophyllites, (see Pl. 1, Figs. 4. 5.) from the stellated disposition of the leaves around the branches.
[480 RELATIONS TO EXISTING VEGETABLES.] the vegetables which gave origin to coal are, 1st, that a large proportion of these plants were vascular Cryptogamiæ, and especially Ferns; 2dly, that among these Cryptogamic plants, the Equisetaceæ attained a gigantic size; 3rdly, that Dicotyledonous plants, which compose nearly two-thirds of living Vegetables, formed but a small proportion of the Flora of these early periods.* 4thly, that although many extinct genera, and certain families have no living representatives, and even ceased to exist after the deposition of the Coal formation, yet are they connected with modern vegetables by common principles
* The value to be attached to numerical proportions of fossil Plants, in estimating the entire condition of the Flora of these early periods, has been diminished by the result of a recent interesting experiment made by Prof. Lindley, on the durability of Plants immersed in water. (See Fossil Flora, No. xvii. vol. iii. p. 4.) Having immersed in a tank of fresh water, during more than two years, 177 species of plants, including representatives of all those which are either constantly present in the coal measures or universally absent, he found:
l. That the leaves and bark of most dicotyledonous Plants are wholly decomposed in 2 years, and that of those which do resist it, the greater part are Coniferæ and Cycadeæ.Although the Results of this experiment in some degree
2. That Monocotyledons are more capable of resisting the action of water, particularly Palms and Scitamineous Plants; but that Grasses and Sedges perish.
3. That Fungi, Mosses, and all the lowest forms of Vegetation disappear.
4. That Ferns have a great Power of resisting water if gathered in a green state, not one of those submitted to the experiment having disappeared, but that their fructification perished.
[481 COMPLEX HISTORY OF COAL.] of structure, and by details of organization, which shew them all to be parts of One grand, and consistent, and harmonious Design .
We may end our account of the Plants to which we have traced the origin of Coal, with a summary view of the various Natural changes, and processes in Art and Industry, through which we can follow the progress of this curious and most important vegetable production .
Few persons are aware of the remote and wonderful Events in the economy of our Planet, and of the complicated applications of human Industry and Science, which are involved in the production of the Coal that supplies with fuel
invalidate the certainty of our knowledge of the entire Flora of each of the consecutive Periods of Geological History, it does not affect our information as to the number of the enduring Plants which have contributed to make up the Coal formation; nor as to the varying proportions, and changes in the species of Ferns and other plants, in the successive systems of vegetation that have clothed our globe.
It may be further noticed, that as both trunks and leaves of Angiospermous dicotyledonous Plants have been preserved abundantly in the Tertiary formations, there appears to be no reason why, if Plants of this Tribe had existed during the Secondary and Transition Periods, they should not also occasionally have escaped destruction in the sedimentary deposits of these earlier epochs.
In Loudon's Mag. Nat. Hist. Jan. 1834, p. 34, is an account of some interesting experiments by Mr. Lukis, on successive changes in the form of the cortical and internal parts of the stems of Succulent plants, (e. g. Sempervivum arboreum) during various stages of decay, which may illustrate analogous appearances in many fossil plants of the coal formation.
[482 STAGES IN THE PRODUCTION OF COAL.] the Metropolis of England. The most early stage to which we can carry back its origin, was among the swamps and forests of the primeval earth, where it flourished in the form of gigantic Calamites, and stately Lepidodendra, and Sigillariæ. From their native bed, these plants were torn away, by the storms and inundations of a hot and humid climate, and transported into some adjacent Lake, or Estuary, or Sea. Here they floated on the waters, until they sank saturated to the bottom, and being buried in the detritus of adjacent lands, became transferred to a new estate among the members of the mineral kingdom. A long interment followed, during which a course of Chemical changes, and new combinations of their vegetable elements, have converted them to the mineral condition of Coal. By the elevating force of subterranean Fires, these beds of Coal have been uplifted from beneath the waters, to a new position in the hills and mountains, where they are accessible to the industry of man. From this fourth stage in its adventures, our Coal has again been moved by the labours of the miner, assisted by the Arts and Sciences, that have co-operated to produce the Steam Engine and the Safety Lamp. Returned once more to the light of day, and a second time committed to the waters, it has, by the aid of navigation, been conveyed to the scene of its next and most considerable change by
[483 FOSSIL CONIFERÆ.] fire; a change during which it becomes subservient to the most important wants and conveniences of Man. In this seventh stage of its long eventful history, it seems to the vulgar eye to undergo annihilation; its Elements are indeed released from the mineral combinations they have maintained for ages, but their apparent destruction is only the commencement of new successions of change and of activity. Set free from their long imprisonment, they return to their native Atmosphere, from which they were absorbed to take part in the primeval vegetation of the Earth. To-morrow, they may contribute to the substance of timber, in the Trees of our existing forests; and having for a while resumed their place in the living vegetable kingdom, may, ere long be applied a second time to the use and benefit of man. And when decay or fire shall once more consign them to the earth, or to the atmosphere, the same Elements will enter on some further department, of their perpetual ministration, in the economy of the material world.
The Coniferæ form a large and very important tribe among living plants, which are characterized,
* See Pl. l. Figs. l. 31. 32. 69.
[484 FOSSIL CONIFERÆ.] not only by peculiarities in their fructification (as Gymnospermous phanerogamiæ),* but also by certain remarkable arrangements in the structure of their wood, whereby the smallest fragment may be identified.
Recent microscopic examinations of fossil woods have led to the recognition of an internal structure, resembling that of existing Coniferæ, in the trunks of large trees, both in the Carboniferous series, and throughout the Secondary formations; and M. Ad. Brongniart has
*We owe to Mr. Brown, the important discovery, that Coniferæ and Cycadeæ are the only two families of plants that have their seeds originally naked, and not enclosed within an Ovary. (see Appendix to Captain King's Voyage to Australia). They have for this reason been arranged in a distinct order, as Gymnospermous Phanerogamiæ. This peculiarity in the Ovulum is accompanied throughout both these families, by peculiarities in the internal structure of their stems, in which they differ from almost all dicotyledonous plants, and in some respects also from each other.
The recognition of these peculiar characters in the structure of the stem, is especially important to the Geological Botanist, be cause the stems of plants are often the only parts which are found preserved in a fossil state.
The occurrence of large coniferous trees in strata of the great Coal formation, was first announced in Mr. Witham's Fossil Vegetables, 1831. It was here stated that the higher and more complex organizations of Coniferæ exist in the Coal fields of Edinburgh and Newcastle, in strata which till lately have been supposed to contain only the simpler forms of vegetable structure.
In the lower region of the Secondary strata, M. Ad. Brongniart has enumerated, among the fossil plants of the New red
[484 LARGEST AND TALLEST LIVING CONIFERÆ.] enumerated twenty species of fossil Coniferæ in strata of the Tertiary series. Many of these last approach more closely to existing Genera than those in the secondary strata, and some are referrible to them .
It has been further shown by Mr. Nicol, (Edin. New Phil. Journal, January, 1834) that some of the most ancient fossil Coniferæ may be referred to the existing genus Pinus, and others to that of Araucaria; the latter of these comprehends some of the tallest among living trees, (see Pl. 1, Fig. 1) and is best known in the Araucaria excelsa, or Norfolk Island Pine.
These discoveries are highly important, as they afford examples among the earliest remains of vegetable life, of identity in minute details of internal organization, between the most ancient
sandstone of the Vosges, four species of Voltzia, a new genus oi Coniferæ, having near affinities to the Araucaria and Cunninghamia. Branches, leaves, and cones of this genus are most abundant at Sultz les Bains, near Strasburgh.
Mr. Witham reckons eight species of Coniferæ among the fossil woods of the Lias; and five species, of which four are allied to the existing genus Thuia, occur in the Oolite formation of Stonesfield. (See Ad. Brongniart's Prod. page 200). For figures of Cones from the Lias and Green-sand near Lyme Regis, and the Inferior oolite of Northamptonshire, see Lindley and Hutton's Fossil Flora, Plates 89, 133, 137
Dr. Fitton has described and flgurcd two very beautiful and perfect cones, one from Purbeck ? and one from the Hastings sand. Geol. Trans. 2nd Series, Vol. iv. Pl. 22, Figs. 9, 10. p. 181 and 230.
[486 ARAUCARIA AND PINUS IN COAL FORMATION.] trees of the primeval forests of our globe, and some of the largest living Coniferæ.*
The structure of Araucarias alone has been as yet identified in trees from the Carboniferous series of Britain. That of ordinary Pines
* The transverse section of any coniferous wood in addition to the radiating and concentric lines represented Pl. 56a, Fig. 7, exhibits under the microscope a system of reticulations by which Coniferæ are distinguishable from other plants. The form of these reticulations magnified 400 times is given in Pl. 56a, Figs. 2, 4, 6. These apertures are transverse sections of the same vessels, which are seen in a longitudinal section at Pl. 56a Fig. 8, cut from the centre towards the bark, and parallel to the medullary rays. These vessels exhibit a characteristic and beautiful structure, whereby a distinction is marked between true Pines and Araucarias. In such a section the small and uniform longitudinal vessels, (Pl. 56a, Fig. 8) which constitute the woody fibre, present at intervals a remarkable appearance of small, nearly circular figures disposed in vertical rows (See Pl. 56a, Figs. 1, 3, 5). These objects under the name of glands or discs, are differently arranged in different species; they are generally circular, but sometimes elliptical, and when near each other, become angular. Each of these discs has near its centre a smaller circular areola. Pl. 56a, Fig. 1, represents their appearance in the Pinus strobus of North America.
In some Coniferæ, the discs are in single rows; in others, in double as well as single rows, e. g. in Pinus strobus, Pl. 56a, Fig. l.
Throughout the entire genus of living Pines, when double rows of discs occur in one vessel, the discs of both rows are placed side by side, and never alternate, and the number of the rows of discs is never more than two.
In the Araucarias the groups of discs are arranged in single, double, triple and sometimes quadruple rows, see Pl. 56a, Fig. 3, 5. They are much smaller than those in the true Pines, scarcely half their size, and in the double rows they always alternate with
[487 PINUS AND ARAUCARIA IN LIAS.] occurs in wood from the Coal formation of Nova Scotia and New Holland
The same ordinary structure of Pines predominates in the fossil wood of the Lias at Whitby; trunks of Araucarias also are found there in the same Lias; and branches, with the leaves still adhering to them, in the Lias at Lyme Regis
Professor Lindley justly remarks that it is an important fact, that at the period of the deposit of the Lias, the vegetation was similar to that of the Southern Hemisphere, not alone in the single fact of the presence of Cycadeæ, but that the Pines were also of the nature of species now found only to the south of the equator. Of
each other, and are sometimes circular, but mostly polygonal. Mr. Nicol has counted a row of not less than fifty discs in a length of the twentieth part of an inch, the diameter of each disc not exceeding the thousandth part of an inch; but even the smallest of these are of enormous size, when compared with the fibres of the partitions bounding the vessels in which they occur.
A trunk of Araucaria forty-seven feet long was found in Cragleith Quarry, near Edinburgh, 1830. (See Witham's Fossil Vegetables, 1833, Pl. 5.) Another, three feet in diameter, and more than twenty-four feet long, was discovered in the same quarries in 1833. (See Nicol on Fossil Coniferæ, Edin. New Phil. Journal, Jan. 1834). The longitudinal sections of this Tree exhibit, like the recent Araucaria excelsa, small polygonal discs, arranged in double, and triple and quadruple rows within the longitudinal vessels; so also does a similar section from the Coal field of New Holland.
See Lindley and Hutton's Fossil Flora, Pl. 88. A fossil cone referrible to Coniferæ, and possibly to the genus Araucaria, from the Lias of Lyme Regis, is represented at Plate 89 of the same work.
[488 ORGANIZATION OF FOSSIL CONIFERÆ.] the four recent species of Araucaria at present known, one is found on the east coast of New Holland, another in Norfolk Island, a third in Brazil, and the fourth in Chili (Foss. Flora, vol. ii. p. 21.)
Whatever result may follow from future investigations, our present information shows that the largest and most perfect fossil Coniferæ, which have been as yet sufficiently examined from the Coal formation and the Lias, are referrible either to the genus Pinus, or Araucaria,* and that both these modifications of the existing Family of Coniferæ date their commencement from that very ancient period, when the Carboniferous strata of the Transition formation were deposited.
* Mr. Nicol states that in fossil woods from the Whitby Lias, when concentric layers are distinctly marked on their transverse section, (Pl. 56", Fig. 2, a, a.) the longitudinal sections have also the structure of Pinus (Pl. 56", Fig. 1.); but when the transverse section exhibits no distinct annual layers, (Pl. 56", Fig. 4.) or has them but slightly indicated, (Pl. 56", Fig. G a) the longitudinal section has the characters of Araucaria. (Pl. 56", Fig. 3, 5.) So also those Coniferæ of the great Coal formation of Edinburgh and Newcastle, which exhibit the structure of Araucaria in their longitudinal section, have no distinct concentric layers; whilst in the fossil Coniferæ from the New Holland and Nova Scotia Coal field, both longitudinal and transverse sections agree with those of the recent tribe of Pinus.
Mr. Witham also observes that the Coniferæ of the Coal formation, and mountain limestone group, have few and slight appearances of the concentric lines, by which the annual layers of the wood are separated, which is also frequently the case with the Trees of our present tropical regions, aiid from this circumstance conjectures that, at the epochs of these formations, the changes of season, as to temperature at least were not abrupt.
[489 CONIFERÆ IN THE SECONDARY SERIES.] Fragments of trunks of Coniferous wood, and occasionally leaves and cones occur through all stages of the Oolite formation, from the Lias to the Portland stone. On the upper surface of the Portland stone, we find the remains of an ancient forest, in which are preserved large prostrate silicified trunks, and silicified stumps of Coniferæ, having their roots still fixed in the black vegetable mould in which they grew. Fragments of coniferous wood are also frequent throughout the Wealden and Green-sand formations, and occur occasionally in Chalk.*
It appears that the Coniferæ are common to fossiliferous strata of all periods; they are least abundant in the Transition series, more numerous in the Secondary, and most frequent in the Tertiary series. Hence we learn that there has been no time since the commencement of terrestrial vegetation on the surface of our Globe, in which large Coniferous trees did not exist; but our prsent evidence is insufficient, to ascertain with accuracy the proportions they bore to the relative numbers of other families of plants, in each of the successive ocological epochs, which are thus connected with our own, by a new and beautiful series of links, derived from one of the most important tribes of the vegetable kingdom.
* There is in the Oxford Museum a fragment of silicified coniferous wood, Perforated by Teredines, found by Rev. Dr. Faussett, in a chalk flint at Lower Hardres, near Canterbury.
[490 FLORA OF THE SECONDARY SERIES.]
VEGETABLES IN STRATA OF THE SECONDARY
THE Flora of the Secondary Series presents characters of an intermediate kind between the Insular vegetation of the Transition series, and the Continental Flora of the Tertiary formations. Its predominating feature consists in the abundant presence of Cycadeæ, (see Pl. 1, Figs 33, 34, 35,) together with Coniferæ, and Ferns. § (See Pl. 1, Figs. 37, 38, 39.)
* See Pl. 1, Figs. 31 to 39.
M. Ad. Brongniart, in his arrangement of fossil plants, has formed a distinct group out of the few species which have been found in the Red-sandstone formation (Gres bigarré) immediately above the Coal. In our division of the strata, this Red-sandstone is included, as an inferior member, in the Secondary series. Five Algæ, three Calamites, five Ferns, and five Coniferæ, two Liliaceæ, and three uncertain Monocotyledonous plants form the entire amount of species which he enumerates in this small Flora.
See also Jæger uber die Pflanzenversteinerungen in dem Bausandstein von Stuttgart, 1827.
We again refer to Witham's Account of Coniferæ from the Lias, in his observations on Fossil Vegetables, 1833.
§ A very interesting account, accompanied by figures, shewing the internal structure of the stems of fossil arborescent Ferns of the Secondary period, is given in Cotta's Dendrolithen, Dresden, 1832; these appear to be chiefly from the New red sandstone of Chemnitz near Dresden.
[491 EXTENT OF FOSSIL AND RECENT CYCADEÆ.] M. Ad. Brongniart enumerates about seventy species of land plants in the Secondary formations, (from the Keuper to the Chalk inclusive;) one half of these are Coniferæ and Cycadeæ, and of this half, twenty-nine are Cycadeæ; the remaining half are chiefly vascular Cryptogamiæ, viz. Ferns, Equisetaceæ, and Lycopodiaceæ. In our actual vegetation, Coniferæ and Cycadeæ scarcely compose a three hundredth part.*
The family of Cycadeæ comprehends only two living Genera; viz. Cycas, (Pl. 58.) and Zamia. (Pl. 59.) There are five known living Species of Cycas and about seventeen of Zamia. Not a single species of the Cycadeæ grows at the present time in Europe; their principal localities are parts of equinoctial America, the West Indies, the Cape of Good Hope, Madagascar, India, the Molucca Islands, Japan, China, and New Holland.
Four or five genera, and twenty-nine species of Cycadeæ, occur in the fossil Flora of the Secondary period, but remains of this family are very
* The fossil vegetables in the Secondary series, although they present many kinds of Lignite, very rarely form beds of valuable Coal. The imperfect coal of the Cleveland Moorlands near Whitby, and of Brora in Sutherland, belong to the inferior region of the Oolite formation. So also does the bituminous coal of Bückeberg near Minden, in Westphalia.
The coal of Hoer in Scania is either in the Wealden formation, or in the Green-sand (Ann. des Sciences Nat. tom. iv. p. 200).
[492 HABIT AND STRUCTURE OF CYCADIÆ.] rare in strata of the Transition, and Tertiary series.
The Cycadeæ form a beautiful family of plants whose external habit resembles that of Palms, whilst their internal structure approximates in several essential characters to that of Coniferæ. In a third respect, (viz, the Gyrate Vernation, or mode in which the leaves are curled up at their
I learn by letter from Count Steinberg, (Aug. 1835.) that he has found Cycadeæ and Zamites in the Coal formation of Bohemia, of which he will publish figures in the 7th and 8th Cahier of his Flore du Monde primitif. This is, I believe, the first example of the recognition of plants of this family in strata of the Carboniferous series.
During a recent visit to the extensive and admirably arranged geological collection in the Museum at Strasbourg, I was in formed by M. Voltz that the stem of a Cycadites in that Museum, described by M. Ad. Brongniart as a Mantellia, from the Muschelkalk of Luneville, is derived from the Lias near that Town. M. Voltz knows no example of any Cycadites from the Muschelkalk. Stems and leaves of Cycadeæ occur also in the Lias at Lyme Regis. (Lind. Foss. Fl. Pl. 143.)
The most abundant deposit of fossil leaves of Cycadeæ in England, is in the Golitic formation on the coast of Yorkshire, between Whitby and Scarborough, (See Phillips' Illustrations of the Geology of Yorkshire.) Leaves of this family occur also in the Golitic slate of Stonesfield. Lindley and Hutton, Foss. Flora, Pl. 172, 175.
In Lindley and Hutton's Fossil Flora, Pl. 136, Figures are given of Cones which he refers to the genus Zamia, from the sandstone of the Wealden formation at Yaverland on the South coast of the I. of Wight.
M. Ad. Brongniart has established a new fossil genus Nilsonia, in the family of Cycadeæ, which occurs at Hoer in Scania, in strata, either of the Wealden or Green-sand formation; and another genus, Pterophyllum, which is found from the New red sand-stone upwards to the Wealden formation.
[493 INTERMEDIATE CHARACTER OF CYCADEÆ.] points within the buds), they resemble Ferns. (See Pl. l. F. 33, 34, 35 and Pl. 58, 59.)
I shall select the family of Cycadeæ from the Fossil Flora of the Secondary period, and shall enter into some details respecting its organization, with a view of showing an example of the method of analysis, by which Geologists are enabled to arrive at information as to the structure and economy of extinct species of fossil vegetables, and of the importance of the conclusions they are enabled to establish. Those who have attended to the recent progress of vegetable Physiology will duly appreciate the value of microscopic investigations, which enable us to identify the structure of vegetables of such remote antiquity, with that which prevails in the organization of living species.
The physiological discoveries that have lately been made with respect to living species of Cycade, have shown them to occupy an intermediate place between Palms, Ferns, and Coniferæ, to each of which they bear certain points of resemblance; and hence a peculiar interest attends the recognition of similar structures in fossil plants, referrible to a family whose characters are so remarkable.
The figure of a Cycas revoluta (Pl. 53,)* represents the form and habit of plants belonging to this beautiful genus. In the magnificent crown
* Drawn from a Plant in Lord Grenville's Conservatory at Dropmore in 1832.
[494 FOSSIL CYCADEÆ IN DORSETSHIRE.] of graceful foliage surrounding the summit of a simple cylindrical trunk, it resembles a Palm. The trunk in the genus Cycas, is usually long. That of C. circinalis rises to 30 feet.* In the genus Zamia it is commonly short.
Our figure of a Zamia pungens: (Pl. 59,) shews the mode of inflorescence in this Genus, by a single cone, rising like a Pine Apple, deprived of its foliaceous top, from within the crown of leaves at the summit of the stem.
The trunk of the Cycadeæ has no true bark, but is surrounded by a dense case, composed of persistent scales which have formed the basis of fallen leaves; these, together with other abortive scales, constitute a compact covering that supplies the place of bark. (See Pl. 58 and 59.)
In the Geol. Trans. of London (vol. iv. part l. New Series) I have published, in conjunction with Mr. De la Beche, an account of the circumstances under which silicified fossil trunks of Cycadeæ are found in the Isle of Portland, immediately above the surface of the Portland stone, and below the Purbeck stone. They are lodged in the same beds of black mould in which they grew, and are accompanied by prostrate
* In Curtis's Botanical Magazine, 1828, Pl. 2826, Dr. Hooker has published an Engraving of a Cycas circinalis which in 1827 flowered in the Botanic Garden at Edinburgh. See Pl. l. Fig. 33.
Copied from an engraving published by Mr. Lambert, of a plant that bore fruit at Walton on Thames, in the conservatory of Lady Tankerville, 1832.
[495 ANCIENT SUBMERGED FOREST.] trunks of large coniferous trees, converted to flint, and by stumps of these trees standing erect with their roots still fixed in their native soil. (See Pl. 57, Fig. 1.)*
Pl. 57, Fig. 3, exhibits similar stumps of trees rooted in their native mould, in the Cliff immediately east of Lulworth Cove. Here the strata have been elevated nearly to an angle of 45°, and the stumps still retain the unnatural inclination into which they have been thrown by this elevation.
The facts represented in these three last figures are fully described and explained in the paper above referred to; they prove that plants be longing to a family that is now confined to the warmer regions of the earth, were at a former period, natives of the southern coast of England.
* The sketch, Pl. 57, Fig. 2, represents a triple series of circular undulations, marked in the stone, which surrounds a single stump, rooted in the dirt-bed in the Isle of Portland. This very Curious disposition has apparently resulted from undulations, produced by winds, blowing at different times in different directions on the surface of the shallow fresh water, from the sediments of which the matter of this stratum was supplied, while the top of this stem stood above the surface of the water. See Geol. Trans. Lond. N. S. vol. iv. p. 17.
The structure of this district affords also a good example of the proofs which Geology discloses, of alternate elevations and submersions of the strata, sometimes gradually, and sometimes violently, during the formation of the crust of our planet.
First. We have evidence of the rise of the Portland stone, till it reached the surface of the sea wherein it was formed.
Secondly. This surface became for a time, dry land, covered by
[496 TRUNKS AND SCALES ONLY PRESERVED.] As no leaves have yet been found with the fossil Cycadeæ under consideration, we are limited to the structure of their trunk and scales, in our search for their distinguishing characters.
I have elsewhere (Geol. Trans. London, N. S. vol. ii. part iii. 1828) instituted a comparison between the internal structure of two species of these fossil trunks, and that of the trunks of a recent Zamia and recent Cycas.*
a temporary forest, during an interval which is indicated by the thickness of a bed of black mould, called the Dirt bed, and by the rings of annual growth in large petrified trunks of prostrate trees, whose roots had grown in this mould.
Thirdly. We find this forest to have been gradually submerged, first beneath the waters of a freshwater lake, next of an estuary, and afterwards beneath those of a deep sea, in which Cretaceous and Tertiary strata were deposited, more than 2000 feet in thickness.
Fourthly. The whole of these strata have been elevated by subterranean violence, into their actual position in the hills of Dorsetshire.
We arrive at similar conclusions, as to the alternate elevation and depressions of the surface of the earth, from the erect position of the stems of Calamites, in sandstone of the lower Oolite formation on the eastern coast of Yorkshire. (See Murchison. Proceedings of Geol. Society of London, p. 391.)
* M. Ad. Brongniart has referred these two fossil species to a new genus, by the name of Mantellia nidiformis and Mantellia cylindrica; in my paper, just quoted, I applied to them the provisional name of Cycadeoidea megalophylla and Cycadeoidea microphylla; but Mr. Brown is of opinion, that until sufficient reasons are assigned for separating them from the genus Cycas or Zamia, the provisional name of Cycadites is more appropriate, as expressing the present state of our knowledge upon this subject. The name Mantellia is already applied by Parkinson (In troduction to Fossil Org. Rem. p. 5:3) to a genus of Zoophytes, which is figured in Goldfuss, T. vi. p. 14.
[497 INTERNAL STRUCTURE OF TRUNKS.] I must refer to the memoir, in which these sections are described, for specific details as to the varied proportions and numerical distribution of these concentric circles of laminated wood and cellular tissue, in the trunks of living and fossil species of Cycadeæ.*
A strict correspondence is also exhibited in
* Plates 60, Fig. 1, and 61, Fig. 1, represent very perfect specimens of fossil Cycadites from Portland, now in the Oxford Museum; both having the important character of Buds protruding from the Axillæ of the leaf stalks.
The section given in Pl. 59, Fig. 2, of the trunk of a recent Zamia horrida, from the Cape of Good Hope, displays a structure similar to that in the section of the fossil Cycadites megalophyllus from the Isle of Portland; (Pl. 60, Fig. 2) each presents a single circle of radiating laminæ of woody fibre, B, placed between a central mass of cellular tissue, A, and an exterior circle of the same tissue, C. Around the trunk, thus constituted of three parts, is placed a case or false bark, D, composed of the persistent bases of fallen leaves, and of abortive scales. The continuation of the same structure is seen at the summit of the stem, Pl. 60, Fig. 1, A. B. C. D.
The Cycadites microphyllus, Pl. 61, Fig. 1, affords a similar approach to the internal structure of the stem in the recent Cycas. The summit of this fossil exhibits a central mass of cellular tissue (A), surrounded by two circles of radiating woody plates, B. b., between these laminated circles, is a narrow circle of cellular tissue, whilst a broader circle of similar cellular tissue (C) is placed between the exterior laminated circle, (b) and the leaf scales (D). This alternation of radiating circles of wood with circles of cellular tissue, is similar to the two laminated circles near the base of a young stem of Cycas revoluta, (Pl. 59, Fig. 3.) This section was communicated to me by Mr. Brown early in 1828, to confirm the analogy which had been suggested from the external surface, between these fossils, and the recent Cycadeæ; and is figured in Geol. Trans. N. S. vol. ii. Pl. 46.
[498 STRUCTURE OF SCALES OR BASES OF LEAF STALKS.] the internal structure of the scales, or bases of leaf stalks surrounding the trunks of our fossil Cycadites, with that of the corresponding scales in the recent species.*
* In Pl. 61, Figs. 2, 3, represent two vertical sections of a Cycadites microphyllus from Portland, converted to Chalcedony. These slices are parallel to the axis of the trunk, and intersect transversely the persistent bases of the Petioles or Leaf-stalks. In each rhomboidal Petiole, we see the remains of three systems of vegetable structure, of which magnified representations are given Pl. 62, Fig. 1, 2, 3. We have, first, the principal mass of cellular tissue (f); secondly, sections of gum vessels (h) irregularly dispersed through this cellular tissue ; thirdly, bundles of vessels, (c), placed in a somewhat rhomboidal form, parallel to, and a little within, the integument of each petiole. These bundles of vessels are composed of vascular woody fibres proceeding from the trunk of the plant towards the leaf. See magnified section of one bundle at Pl. 62, Fig. 3, c'.
A similar arrangement of nearly all these parts exists in the transverse section of the leaf stalks of recent Cycadeæ. In Cycas circinalis, and C. revoluta, and Zamia furfuracea, the bundles of vessels are placed as in our fossil, nearly parallel to the integument. In Zainia spiralis, and Z. horrida, their disposition within the Petiole, is less regular, but the internal structure of each bundle is nearly the same. In Pl. 62, Fig. A shews the place of these bundles of vessels in a transverse section of the leaf stalk of Zamia spiralis; Fig. A. c'. is the magnified appearance of one of the bundles in this section; Fig. B. c" is the magnified transverse section of a similar bundle of vessels in the petiole of Zamia horrida. In this species the vascular fibres are smaller and more numerous than in Z. spiralis, and the opake lines less distinct. Both in recent and fossil Cycadeæ the component vascular fibres of these bundles are in rows approximated so closely to each other, that their compressed edges give an appearance of opake lines between the rows of vascular fibres, (see Pl . 62, Fig. 1, c'. Fig. B., c". and Fig. 3, c'.) These bundles
[499 INCREASE OF CYCADEÆ BY BUDS.]
Mode of increase by Buds the same in recent and fossil Cycadeæ.
The Cycas revoluta figured in Pl. 58* possesses a peculiar interest in relation to both our
of vessels seem to partake of the laminated disposition of the woody circle within the trunk.
An agreement is found also in the longitudinal sections of the Petioles of recent and fossil Cycadeæ. Pl. 62, Fig 1, is the longitudinal section of part of the base of a Petiole of Zamia spiralis, magnified to twice the natural size. It is made up of cellular tissue, (f), interspersed with gum vessels, and with long bundles of vascular fibres, (c) proceeding from the trunk towards the leaf. On the lower integument, (b') is a dense coating of minute curling filaments of down or cotton, (a) which being re peated on each scale, renders the congeries of scales surrounding the trunk, impervious to air and moisture.
A similar disposition is seen in the longitudinal section of the fossil Petiole of Cycadites microphyllus represented at Pl. 62, Fig. 2, and magnified four times. At f, we have cellular tissue interspersed with gum vessels, h. Beneath c, are longitudinal bundles of vessels; at b, is the integument; at a, a most beautiful petrifaction of the curling filaments of down or cotton, proceeding from the surface of this integument.
In the vascular bundles within the fossil Petioles, (c) Mr. Brown has recognized the presence of spiral, or scalariform vessels (Vasa scalariformia) such as are found in the Petioles of recent Cycadeæ; he has also detected similar vessels, in the laminated circle within the trunk of the fossil Buds next to be described. The existence of vessels with discs peculiar to recent Cycadeæ and Coniferæ, such as have been described in speaking of fossil Coniferæ, has not yet been ascertained.
* This plant had been living many years, in Lord Grenville's Conservatory at Dropmore. In the autumn of 1827, the external part of the scales was cut away to get rid of insects: in the
[500 INCREASE OF CYCADEÆ BY BUDS.] fossil species, in consequence of its protruding a series of buds from the axillæ of many of the scales around its trunk. These buds explain analogous appearances at the axillæ of many fossil scales on Cycadites megalophyllus, and Cycadites microphyllus, (see Pl. 60, Fig. 1, and Pl. 61, Fig. 1,) and form an important point of agreement in the Physiology of the living and fossil Cycadeæ.*
following spring the buds began to protrude. Similar buds appeared also in the same conservatory on a plant of the Zamia spiralis from New Holland. In vol. vi. p. 501, Horticult. Trans. leaves are stated to have protruded from the scales of a decayed trunk of Zamia horrida in a conservatory at Petersburgh.
I learn from Professor Henslow, that the trunk of a Cycas revoluta, which in 1830 produced a Cone loaded with ripe drupæ, in Earl Fitzwilliam's hothouse at Wentworth, threw out a number of buds, from the axillæ of the leaf-scales soon after the Cone was cut off from its summit. In Linn. Trans. vol. vi. tab. 29, is a figure of a similar cone which bore fruit at Farnham Castle, 1799.
It is stated in Miller's Gardener's Dictionary, that the Cycas revoluta was introduced into England about 1758, by Captain Hutchinson; his ship was attacked, and the head of the plant shot off, but the stem being preserved, threw out several new beads, which were taken off, and produced as many plants.
* In the fossil trunk of Cycadites microphyllus, Pl. 61, Fig. 1, we see fourteen Buds protruding from the axillæ of the leaf stalks, and in Pl. 60, Fig. 1, we have three Buds in a similar position in Cycadites megalophyllus.
In Pl. 61, Figs. 2, 3, exhibit transverse sections of three Buds of Cycadites microphyllus. The section of the uppermost bud, Fig. 3, g, passes only through the leaf stalks near its crown. The section of the bud, Fig. 3. d, being lower down in the embryo trunk, exhibits a double woody circle, arranged in radiating
[501 CHARACTERS OF FOSSIL CYCADITES.] Thus, we see that our fossil Cycadites are closely allied by many remarkable characters of structure, to existing Cycadeæ.
1. By the internal structure of the trunk, containing a radiating
or circles, of woody fibre, embedded in cellular tissue. 2. By the
of their outer case, composed of persistent bases of petioles, in place
of a bark; and by all the minute details in the internal organization
each Petiole. 3. By their mode of increase by Buds protruded from germs
in the Axillæ of the Petioles.
However remote may have been the time when
plates, resembling the double woody circle in the mature trunk, Pl. 61, 1, B, b. But in Pl. 61, Fig. 2, the laminated circle within the embryo trunk near d, is less distinctly double, as might be expected in so young a state.
At Pl. 132, Fig. 3, d, and'd', we see magnified representations of a portion of the embryo circle within the Bud, Pl. 61. Fig. 3,'d. These woody circles within the buds, are placed between an exterior circle of cellular tissue, interspersed with gum vessels, and a central mass of the same tissue, as in the mature stems.
On the right of the lower bud, Pl. 61, Fig. 3, above b, and in the magnified representation of the same at Pl. 62, Fig. 3, e, we have portions of a small, imperfect laminated circle. Similar imperfect circles occur also near the margin of the sections, Pl. 61, Figs. 2, 3, at e, c', e"; these may be imperfectly developed Buds, crowded like the small Buds near the base of the living Cycas, Pl. 58: or they may have resulted from the confluence of the bundles of vessels, in the Bases of leaves, forced together by pressure, connected with a diminution or decay of their cellular substance. The normal position of these bundles of vessels is seen magnified in Pl. 62. Fig. 3. c. and in nearly all the Sections of Bascs of petioles in Pl. 61. Fig. 2.
[502 LINK SUPPLIED BY CYCADEÆ.] these Prototypes of the family of Cycadeæ ceased to exist, the fact of their containing so many combinations of peculiarities identical with those of existing Cycadeæ, connects these an cient arrangements in the Physiology of fossil Botany, with those which now characterize one of the most remarkable families among existing plants. In virtue of these peculiar structures, the living Cycadeæ form an im portant link, which no other Tribe of plants supplies, connecting the great family of Coniferæ, with the families of Palms and Ferns, and thus fill up a blank, which would otherwise have separated these three great natural divisions of dicotyledonous, monocotyledonous, and acotyledonous plants.
The full development of this link in the Secondary periods of Geological history, aflbrds an important evidence of the Uniformity of Design which now pervades, and ever has pervaded, all the laws of vegetable life.
Facts like these are inestimably precious to the Natural Theologian; for they identify, as it were, the Artificer, by details of manipulation throughout his work. They appeal to the Physiologist, in language more commanding than human Eloquence; the voice of very stocks and stones, that have been buried for countless ages in the deep recesses of the earth, proclaiming the universal agency of One all-directing,
[503 PANDANEÆ.] all-sustaining Creator, in whose Will.
and Power, these harmonious systems originated, and by whose Universal Providence, they are, and have at all times been, maintained.
The Pandaneæ or Screw-Pines, form a monocotyledonous family which now grows only in the warmer zones, and chiefly within the influence of the sea; they abound in the Indian Archipelago, and the islands of the Pacific Ocean. Their aspect is that of gigantic Pine apple plants having arborescent stems. (See Pl. 63, Fig. 1.)
This family of Plants seems destined, like the Cocoanut Palm, to be among the first vegetable Colonists of new lands just emerging from the ocean; they are found together almost universally by navigators on the rising Coral islands of tropical seas. We have just been considering the history of the fossil stems of Cycadeæ in the Isle of Portland, from which we learn that Plants of that now Extra-european family were natives of Britain, during the period of the Oolite formation. The unique and beautiful fossil fruit represented in our figures (Plate 63, Figs. 2, 3, 4,) affords probable evidence of the existence of another tropical family nearly allied to the Pandaneæ at
[504 FOSSIL FRUIT RELATED TO PANDANEÆ.] the commencement of the great Oolitic series in the Secondary formations.*
In structure this fossil Fruit approaches nearer to Pandanus than to any other living plant, and viewing the peculiarities of the fruit of Pandaneæ, in connection with the office assigned
* This fossil was found by the late Mr. Page, of Bishport near Bristol, in the lower region of the Inferior Oolite formation on the E. of Charmouth, Dorset, and is now in the Oxford Museum. The size of this fruit is that of a large orange, its surface is occupied by a stellated covering or Epicarpium, composed of hexagonal Tubercles, forming the summits of cells, which occupy the entire circumference of the fruit. (Figs. 2, a. 3, a. 4, a. 8, a.)
Within each cell is contained a single seed, resembling a small grain of Rice more or less compressed, and usually hexagonal, Figs. 5, 6, 7, 8, 10. Where the Epicarpium is removed, the points of the seeds are seen, thickly studded over the surface of the fruit, (Fig. 2, 3, e.) The Bases of the cells (Fig. 3 and 10 c.) are separated from the receptacle, by a congeries of foot-stalks (d) formed of a dense mass of fibres, resembling the fibres beneath the base of the seeds of the modern Pandanus (Fig. 13, 14, 15, d.) As this position of the seeds upon foot-stalks composed of long rigid fibres, at a distance from the receptacle, is a character that exists in no other family than the Pandaneæ, we are hereby enabled to connect our fossil fruit with this remarkable tribe of plants, as a new genus, Podocarya. I owe the suggestion of this name, and much of my information on this subject, to the kindness of my friend, Mr. Robert Brown.
The large spherical fruit of Pandanus, hanging on its parent tree is represented at Pl. 63, Fig. I . Fig. 11 is the summit of one of the many Drupes into which this fruit is usually divided. Each cell when not barren contains a single oblong slender seed; the cells in each drupe vary from two to fourteen in number, and many of them are abortive, (Fig. 13.) The seeds within each
[505 FUNCTIONS OF PANDANEÆ.] n the Economy of nature, to this family of sea-side plants, viz, to take the first possession of new-formed land, just emerging from the water, we see in the disposition of light buoyant fibres within the interior of these fruits, an arrangement peculiarly adapted to the office of vegetable colonization.* The sea-side locality of the Pandaneæ, causes many of their fruits to fall into the water, wherein they are drifted by the winds and waves, until they find a resting place upon some distant shore. A single drupe of Pandanus, thus charged with seeds, transports the elements of vegetation to the rising
drupe of Pandanus are enclosed in a hard nut, of which sections are given at Figs. 14, 15. These nuts are wanting in the Podocarya, whose seeds are smaller than those of Pandaneæ, and not collected into drupes, but dispersed uniformly in single cells over the entire circumference of the fruit. (See Pl. 63, Figs. 3, 8, 10.) The collection of the seeds into drupes surrounded by a hard nut, in the fruit of Pandanus, forms the essential difference between this genus, and our new genus, Podocarya.
In the fruit of Pandanus, Pl. 63, Figs. 11, 16, 17, the summit of each cell is covered with a hard cap or tubercle, irregularly hexagonal, and crowned at its apex with the remains of a withered stigma. We have a similar covering of hexagonal tubercles over the cells of Podocarya (Pl. 63, Figs. 2, a. 8, a. 10, a.) The remains of a stigma appear also in the centre of these hexagons above the apex of each seed. (Figs. 8, a, 10, a.)
* There is a similar provision for transporting to distant regions of the Ocean, the seeds of the other family of sea-side plants which accompanies the Pandanus, in the buoyant mass of fibrous covering that surrounds the fruit of the Cocoa-nut.
[506 VEGETABLE COLONIZATION.] volcanic and coral islands of the
Pacific. The seed thus stranded upon new-formed land, produces a plant
which has peculiar provision for its support on a surface destitute of
soil, by long and large aerial roots protruded above the ground around
the lower part of its trunk. (See Pl. 63.
Fig. 1.) These roots on reaching the ground are calculated to prop up the plant as buttresses surrounding the basis of the stem, so that it can maintain its erect position, and flourish in barren sand on newly elevated reefs, where little soil has yet accumulated.
We have as yet discovered no remains of the leaves, or trunk of Pandaneæ in a fossil state, but the presence of our unique fruit in the Inferior Oolite formation near Charmouth, carries us back to a point of time, when we know from other evidence that England was in a state of new-born land, emerging from the seas of a tepid climate and shews that combinations of vegetable structure such as exist in the modern Pandaneæ, adapted in a peculiar manner to the office of vegetable colonization, prevailed also at the time when the Oolite rocks were in process of formation.
This fruit also adds a new link to the chain of evidence, which makes known to us the Flora of the Secondary periods of geology, and therein discloses fresh proofs of Order, and Harmony, and of Adaptation of peculiar means to peculiar
[507 VEGETABLES IN THE TERTIARY FORMATIONS.] ends; extending backwards from the actual condition of our Planet through the manifold stages of change, which its ancient surface has undergone.*
VEGETABLES IN STRATA OF THE TERTIARY SERIES.
IT has been stated that the vegetation of the Tertiary period presents the general character of that of our existing Continents within the Temperate Zone. In Strata of this Series, Dicotyledonous Plants assume nearly the same proportions as at present, and are four or five times more numerous than the Monocotyledonous; and the greater number of fossil Plants, although of extinct species, have much resemblance to living Genera.
This third great change in the vegetable kingdom is considered to supply another argument in favour of the opinion, that the temperature of the Atmosphere, has gone on continually diminishing from the first commencement of life upon our globe.
* Fruits of another genus of Pandaneæ, to which Mr. Ad. Brongniart has given the name of Pandanocarpum, (Prodrome, p. 138,) occur together with fruits of Cocoa nut, at an early period of the Tertiary formations, among the numerous fossil fruits that are found in the London-clay of the Isle of Sheppey.
See Pl. 1, Figs. 66 to 72.
[508 DICOTYLEDONOUS PLANTS.] The number of species of plants in the various divisions of the Tertiary strata, is as yet imperfectly known. In 1828, M. Ad. Brongniart considered the number then discovered, but not all described, to be 166. Many of these belonging to Genera at that time not determined. The most striking difference between the vegetables of this and of the preceding periods is the abundance in the Tertiary series, of existing forms of Dicotyledonous Plants and large trees, e. g. Poplars, Willows, Elms, Chestnuts, Sycamores, and many other Genera whose living species are familiar to us.
Some of the most remarkable accumulations of this vegetation are those, which form extensive beds of Lignite and Brown~coal.* In some parts of Germany this Brown-coal occurs in strata of more than thirty feet in thickness, chiefly composed of trees which have been drifted, apparently by fresh water, from their place of growth, and spread forth in beds, usually alternating with sand and clay, at the bottom of then existing lakes or estuaries.
The Lignite, or beds of imperfect and stinking Coal near Poole in Dorset, Bovey in Devon, and Soissons in France, have been referred to the first, or Eocene period of the Tertiary formations.
* See an admirable article on Lignites by Alexandre Brougniart in the 26th vol. of the Dictionnaire des Sciences Naturelles.
[509 BROWN-COAL AND LIGNITE.] To the same period probably belongs the Surturbrand of Iceland, (See Henderson's Iceland, vol. ii. p.14.) and the well-known examples of Brown-coal on the Rhine near Cologne and Bonn, and of the Meisner mountain, and Habichtswald near Cassel. These formations occasionally contain the remains of Palms, and Professor Lindley has lately recognized, among some specimens found by Mr. Homer in the Brown-coal near Bonn (See Ann. Phil. Lond. Sept. 1833, V. 3, p. 222), leaves closely allied to the Cinnamomum of our modern tropics, and to the Podocarpus of the southern hemisphere.*
* At Pützberg near Bonn, six or seven beds of Brown-coal alternate with beds of sandy clay and plastic clay. The trees in the Brown-coal are not all parallel to the planes of the strata, but cross one another in all directions, like the drifted trees now accumulated in the alluvial plains, and Delta of the Mississippi; (See Lyell's Geology, 3d edit. vol. i. p. 272.) some of them are occasionally forced even into a vertical position. In one vertical tree at Pützberg, which was three yards in diameter, M. Nöggerath counted 792 concentric rings. In these rings we have a chronometer, which registers the lapse of nearly eight centuries, in that early portion of the Tertiary period which gave birth to the forests, that supplied materials for the formation of the Brown-coal.
The fact mentioned by Faujas that neither roots, branches, or leaves are found attached to the trunks of trees in the Lignite at Bruhl and Liblar near Cologne, seems to show that these trees did not grow on the spot, and that their more perishable parts have been lost during their transport from a distance.
In the Brown-coal Formation near Bonn, and also with the Surturbrand of Iceland, are found Beds that divide into Laminæ
[510 COAL OF MIOCENE PERIOD.] In the Molasse of Switzerland, thcre are many similar deposits affording sometimes Coal of considerable purity, formed during the second, or Miocene period of this series, and usually containing fresh water shells. Such are the Lignites of Vernier near Geneva, of Paudex and Moudon near Lausanne, of St. Saphorin near Vevay, of Kæpfnach near Horgen on the lake of Zurich, and of Œningen near Constance.
The Brown-coal at Œningen forms thin beds of little importance for fuel, but very perfect remains of vegetables are dispersed in great abundance through the marly slates and limestone quarries which are worked there, and afford the most perfect history of the vegetation of the Miocene Period, which has yet come within our reach.*
as thin as paper (Papier Kohle) and are composed entirely of a congeries of many kinds of leaves. Henderson mentions the leaves of two species of Poplar, resembling the P. tremula and P. balsamifera, and a Pine, resembling the Pinus abies as occurring in the Surturbrand of Iceland.
Although we have followed Mr. Brongniart in referring the deposits here enumerated to the first, or Eocene period of the Tertiary series, it is not improbable that some of them may be the products of a later era, in the Miocene or Pliocene periods. Future observations on the Species of their animal and vegetable remains will decide the exact place of each, in the grand Series of the Tertiary formations.
* I have recently been favoured by Professor Braun of Cansruhe, with the following important and hitherto unpublished catalogue, and observations on the fossil plants found in the
[511 FOSSIL PLANTS AT ŒNINGEN.] No distinct catalogues of plants found in the Pliocene, or most recent periods of the Tertiary series, have yet been published.
Freshwater formation of Œningen, which has been already spoken of in our account of fossil fishes. The plants enumerated in this catalogue, were collected during a long series of years by the inmates of a monastery near Œningen, on the dissolution of which they were removed to their present place in the Museum of Carlsruhe. It appears by this catalogue that the plants of Œningen afford examples of thirty-six species belonging to twenty-five genera of the following families.
This table shews the great preponderance of Dicotyledonous plants in the Flora of Œningen, and affords a standard of comparison with those of the Brown-coal of other localities in the Tertiary series. The greater number of the species found here correspond with those in the Brown-coal of the Wetteraw and vicinity of Bonn.
Amid this predominance of dicotyledonous vegetables, not a single herbaceous plant has yet been found excepting some fragments
[512 FOSSIL PALMS.]
The discovery of the remains of Palm Trees in the Brown-coal of Germany has been already
of Ferns and Grasses, and many remains of aquatic plants: all the rest belong to Dicotyledonous, and Gymnospermous ligneous plants.
Among these remains are many single leaves, apparently dropped in the natural course of vegetation; there are also branches with leaves on them, such as may have been torn from trees by stormy weather; ripe seed vessels; and the persistent calix of many blossoms.
The greater part of the fossil plants at Œningen (about two thirds) belong to Genera which still grow in that neighbourhood; but their species differ, and correspond more nearly with those now living in North America, than with any European species, the fossil Poplars afford an example of this kind.
On the other hand, there are some Genera, which do not exist in the present Flora of Germany, e. g. the Genus Diospyros; and others not in that of Europe, e. g. Taxodium, Liquidambar, Juglans, Gleditschia.
Judging from the proportions in which their remains occur, Poplars, Willows, and Maples were the predominating foliaceous trees in the former Flora of Œningen . Of two very abundant fossil species, one, (Populus latior,) resembles the modern Canada Poplar; the other, (Populus ovalis) resembles the Balsam Poplar of North America.
The determination of the species of fossil Willows is more difficult. One of these (Salix angustifolia) may have resembled our present Salix viminalis.
Of the genus Acer, one species may be compared with Acer campestre, another with Acer pseudoplatanus; but the most frequent species, (Acer protensum,) appears to correspond most nearly with the Acer dasycarpon of North America; to another
[513 PALMS IN TERTIARY FORMATIONS.] noticed; and the more frequent occurrence of similar remains of this interesting family, in the Tertiary formations of France, Switzerland, and
species, related to Acer negundo, Mr. Braun gives the name of Acer trifoliatum. A fossil species of Liquidambar (L. europeuin, Braun.) differs from the living Liquidambar styracifluum of America, in having the narrower lobes of its leaf terminated by longer points, and was the former representative of this genus in Europe. The fruit of this Liquidambar is preserved, and also that of two species of Acer and one Salix.
The fossil Linden Tree of Œningen resembled our modern large leaved Linden tree (Tilia grandiflora.)
The fossil Elm resembled a small leaved form of Ulmus campestris.
Of two species of Juglans, one (J. falcifolia) may be compared with the American J. nigra; the other, with J. Alba, and, like it, probably belonged to the division of nuts with bursting external shells, (Carya Nuttal.)
Among the scarcer plants at Œningen, is a species of Diospyros (D. brachysepala.) A remarkable calyx of this plant is preserved, and shews in its centre the place where the fruit separated itself: it is distinguished from the living Diospyros lotus of the South of Europe by blunter and shorter sections.
Among the fossil shrubs are two species of Rhamnus; one of these (R. multinervis, Braun) resembles the R. alpinus, in the costation of its leaf. The second and most frequent species, (R. terminalis, Braun) may with regard to the position and costation of its leaves, be compared in some degree with R. catharticus, but differed from all living species in having its flowers placed at the tips of the plant.
Among the fossil Leguminous plants is a leaf more like that of a fruticose Cytisus than of any herbaceous Trefoil.
Of a Gleditschia, (G. podocarpa, Braun) there are fossil pinnated leaves and many pods; the latter seem, like the G. monasperma of North America, to have been single seeded, and are small and short, with a long stalk contracting the base of the pod.
With these numerous species of foliaceous woods, are found also
[514 PALMS IN SECONDARY AND TRANSITION SERIES.] England, whilst they are comparatively rare in strata of the Secondary and Transition series,
a few species of Conifera~. One species of Abies is still undetermined; branches and small cones of another tree of this family (Taxodiuni europeum Ad. Brong.) resemble the Cypress of Japan (Taxodium Japonicum.)
Among the remains of aquatic plants are a narrow-leaved Potamogeton; and an Isoetes, similar to the I. lacustris now found in small lakes of the Black Forest, but not in the Lake of Constance.
The existence of Grasses at the period when this formation was deposited, is shewn by a well preserved impression of a leaf, similar to that of a Triticum, turning to the right, and on which the costation is plainly expressed.
Fragments of fossil Ferns occur here, having a resemblance to Pteris aquilina and Aspidium Filix mas.
The remains of Equisetum indicate a species resembling E. palustre.
Among the few undetermined remains are the five-cleft and beautiful veined impressions of the Calyx of a blossom, which are by no means rare at Œningen.
No remains of any Rosaceæ have yet been discovered at this place." Letter from Prof. Braun to Dr. Buckland, Nov .25, l835.
In addition to these fossil Plants, the strata at Œningen contain many species of freshwater Shells, and a remarkable collection of fossil Fishes, which we have before mentioned, P. 285. In the family of Reptiles they present a very curious Tortoise, and a gigantic aquatic Salamander, more than three feet long, the Homo Diluvii testis of Scheuchzer. A Lagomys and fossil Fox have also been found here. (See Geol. Trans. Lond. N. S. vol. iii. p. 287.)
In Oct. 1835, I saw in the Museum at Leyden, a living Salamander three feet long, the first ever brought alive to Europe, of a species nearly allied to the fossil Salamander of Œningen. This animal was brought by Dr. Siebold from a lake within the crater of an extinct volcano, on a high mountain in Japan. it fed greedily on small fishes, and frequently cast its epidermis.
[515 DISTRIBUTION OF RECENT AND FOSSIL PALMS.] suggests the propriety of consigning to this part of our subject the few observations we have to make on their history.
The existing family of Palms* is supposed to consist of nearly a thousand species, of which the greater number are limited to peculiar regions of the torrid Zone. If we look to the geological history of this large and beautiful family, we shall find that although it was called into existence, together with the most early vegetable forms of the Transition period, it presents very few species in the Coal formation, (See Lindley's Foss. Flora, No. XV, Pl. 142, P. 163,) and occurs sparingly in the Secondary series ; but in the Tertiary formation we have abundant stems and leaves, and fruits, derived from ,Palms.
Fossil Trunks of Palm Trees.
The fossil stems of Palms are referrible to many species; they occur beautifully silicified in the Tertiary deposits of Hungary, and in the Calcaire Grossier of Paris.§ Trunks of Palms are found
* See Pl. 1, Figs. 66, 67, 68.
See Sprengel's Account of Endogenites Palmacites in New red sandstone, near Chemnitz, (Halle, 1828.) and Cotta's Dendrolithen, (Dresden and Leipsig, 1832, Pl. ix, x.)
Eight species in the family of Palms are given in Ad. Brongniart's list of the fossils of the Tertiary Series.
§ Our figure, Pl. 64, Fig. 2, represents the summit of a
[516 PETRIFIED STEMS OF PALM TREES.] also in the Fresh water formation of Mont Martre.* — It is stated, that at Liblar, near Cologne, they have been seen in a vertical position. Beautifully silicified stems of Palm Trees abound in Antigua, and in India, and on the banks of the Irawadi, in the kingdom of Ava.
It is not surprising to find the remains of Palms in warm latitudes where plants of this family are now indigenous, as in Antigna or India; but their occurrence in the Tertiary formations of Europe, associated with the remains of Crocodiles and Tortoises, and with marine shells, nearly allied to forms which are at present found in seas
beautiful fossil Trunk in the Museum at Paris, allied to the family of Palms, and nearly four feet in circumference, from the lower region of the Calcaire Grossier at Vaillet near Soissons. M. Brongniart has applied to this fossil the name of Endogenites echinatus. The projecting bodies that surround it, like the foliage of a Corinthian Capital, are the persistent portions of fallen Petioles which remain adhering to the stem after the leaves themselves have fallen off. They have a dilated base embracing one-fourth or one-third of the stem; the form of these bases, and the disposition of their woody tissue in fasciculi of fibres, refer this fossil to some arborescent Monocotyledonous Tree allied to Palms.
* Prostrate trunks of Palm trees of considerable size are found in the argillaceous marl beds above the Gypsum strata of the Paris Basin, together with shells of Lymnea and Planorbis; as these Trunks occur here in fresh water deposits they can not have been drifted by marine current from distant regions, but were probably natives of Europe, and of France.
It is not shewn whether these Palm trees were drifted into this position, or are still standing in the spot whereon they grew like the Cycadites and Coniferæ in the Isle of Portland.
[517 FOSSIL LEAVES OF PALM TREES.] of a warm temperature, seems to indicate that the climate of Europe during the Tertiary period, was warmer than it is at present.
Fossil Palm leaves.
We have seven known localities of fossil Palm leaves, in the Tertiary strata of France, Switzerland, and the Tyrol; and among them at least three species, of flabelliform leaves, all differing not only from that of the Chamærops humilis, the only native palm of the South of Europe, but also from every known living species.* These leaves are too well preserved to have endured transport by water from a distant region, and must apparently be referred to extinct species, which, in the Tertiary period, were indigenous in Europe.
No pinnated Palm leaf has yet been found in the Tertiary Strata, although the number of these forms among existing palms, is more than double that of the flabelliform leaves.
* The leaf represented in Pl. 64. fig. l. is that of flabelliform Palm (Palmacites Larnanonis), from the Gypsum of Aix in Provence; similar leaves have been found in three other parts of France, near Amiens, Mans, and Angers, all in strata of the Tertiary epoch . Another species (Palmacites Parisiensis) has been found in the Calcaire Grossier, near Versailles (Cuvier and Brongniart, Geognosie des Environs de Paris, Pl. 8, fig. l. E.) A third species of Palm leaf (Palmacites flabellatus) occurs in the Molasse of Switzerland, near Lausanne, and in the Lignite of Hœring, in Tyrol. See Pl. l. figs. 13. 66.
The Date, Cocoa-nut Palm, and Areca are familiar examples of Palms having pinnated leaves. See Pl. l. figs. 67. 68.
[518 FOSSIL FRUITS OF PALMS.]
Fossil Fruits of Palms.
Many fossil fruits of the Tertiary period be long to the family of Palms, all of which, according to M. Ad. Brongniart, seem derived from Genera that have pinnated leaves. Several such fruits occur in the Tertiary clay of the Island of Sheppey; among which are the Date,* now peculiar to Africa and India; the Cocoa-nut, which grows universally within the tropics; the Bactris, which is limited to America; and the Areca, which is found only in Asia. Not one of these can be referred to any flabelliform palm. Fossil Cocoa-nuts occur also at Brussels, and at Liblar near Cologne, together with fruits of the Areca.
Although all these fruits belong to Genera whose leaves are pinnated, no fossil pinnated Palm leaves (as we have just stated), have yet been found in Europe. It seems therefore most likely, from the mode in which so large a number of miscellaneous fruits are crowded together in the Isle of Sheppey, mixed with marine shells and fragments of timber, almost always perforated by Teredines, that the fruits in question were drifted by marine currents from a warmer
* See Parkinson's Org. Rem. Vol. i. Pl. VI . fig. 4, 9.
* See Parkinson's Org. Rem. Vol. i. Pl. VII. fig. 1-5. M. Brongniart says, these fruits are undoubtedly of the Genus Cocos, near to Cocos lapidea, of Gærtner.
[519 TROPICAL FRUITS IN SHEPPEY.] climate than that which Europe presented after the cominencement of the Tertiary Epoch; in the same manner as tropical seeds and logs of mahogany are now drifted from the Gulf of Mexico to the Coasts of Norway and Ireland.
Besides the fruits of Palms, the Isle of Sheppey presents an assemblage of many hundred species of other fruits,* most of them apparently tropical; these could scarcely have been accumulated, as they are, without a single leaf of the tree on which they grew, and have been associated with drifted timber bored by Teredines, by any other means than a sea current.
We have no decisive information as to the number of species of these fossil fruits; they have been estimated at from six to seven hundred. In the same clay with them are found
* According to M. Ad. Brongniart, many of these have near relation to the aromatic fruits of the Amomum (cardomom), they are triangular, much compressed, and umbilicated at the summit, which presents a small circular areola, apparently the cicatrix of an adherent calyx; within are three valves. A slight furrow passes along the middle of each plain surface, similar to that on the fruit of many scitamineous plants. These Sheppey fruits, however, cannot be identified with any known Genus of that Family, but approach so nearly to it, that Ad. Brongniart gives them the name of Amomocarpum.
See Parkinson's Organic Remains, Vol. i. Pl. 6, 7. Jacob's Flora Favershamensis. And Dr. Parsons, in Phil. Trans. Lond. 1757, Vol. 50, page 396, Pl. XV. XVI. An immense collection of these fruits is preserved in the British Museum, another in the Museum at Canterbury, and a third in that of Mr. Bowerbank, in London.
[520 VEGETABLES OF THREE EPOCHS.] great numbers of fossil Crustaceans, and also the remains of many fishes, and of Crocodiles, and aquatic Tortoises.
As the drifted seeds that occur in Sheppey seem to have been collected by the action of marine currents, the history of European vegeta tion during the Tertiary period, must be sought for in those other remains of plants, whose state and circumstances show that they have grown at no great distance from the spot in which they are now found.*
The following is a summary of what is yet known, respecting the varying conditions of the Flora of the three great periods of Geological history we have been considering.
The most characteristic distinctions between the vegetable remains of these periods are as follows. In the first period, the predominance of vascular Cryptogamic, and comparative rarity of Dicotyledonous plants. In the second, the approximation to equality of vascular Cryptogamic, and Dicotyledonous plants. In the third, the predominance of Dicotyledonous, and rarity of
* The beautiful Amber, which is found on the eastern shores of England, and on the Coasts of Prussia and Sicily, and which is supposed to be fossil resin, is derived from beds of Lignite in Tertiary strata. Fragments of fossil gum were found near London in digging the tunnel through the London clay at Highgate.
The dicotyledonous plants of the Transition and Secondary
[521 NUMBERS OF FOSSIL AND RECENT PLANTS.] vascular Cryptogamic plants. Among existing vegetables almost two thirds are Dicotyledonous.
The Remains of Monocotyledonous Plants occur, though sparingly, in each Period of Geological formations.
The number of fossil plants as yet described is about five hundred; nearly three hundred of these are from strata of the Transition series; and almost entirely from the Coal formation.
About one hundred are from strata of the Secondary series, and more than a hundred from for mations of the Tertiary series. Many additional species have been collected from each of these series, but are not yet named.
As the known species of living vegetables are more than fifty thousand, and the study of fossil botany is as yet but in its infancy, it is probable that a large amount of fossil species lies hid in the bowels of the earth, which the discoveries of each passing year will be continually bringing to light.
The plants of the First period are in a great measure composed of Ferns, and gigantic Equisetaceæ; and of families, of intermediate character between existing forms of Lycopodiaceæ and Coniferæ, e. g. Lepidodendriæ, Sigillariæ, and Stigmariæ; with a few Coniferæ.
Of Plants of the Second period, about one third
formations present only that peculiar tribe of this class, which is made up of Cycadeæ and Coniferæ, viz. Gymnospermous Pha nerogamiæ.
[522 PREVAILING FAMILIES IN EACH EPOCH.] are Ferns; and the greatest part of the remain der are, Cycadeæ and Coniferæ, with a few Liliaceæ. More species of Cycadeæ occur among the fossils of this period, than are found living on the present surface of the earth. They form more than one third of the total known fossil Flora of the Secondary formations; whilst of our actual vegetation, Cycadeæ are not one two-thousandth part.
The vegetation of the Third period approximated closely to that of the existing surface of the globe.
Among living families of plants, Sea weeds, Ferns,
Equisetaceæ, Cycadeæ and Coniferæ, bear the nearest
to the earliest forms of vegetation that have existed upon our planet.
The family which has most universally pervaded every stage of vegetation is that of Coniferæ; increasing in the number and variety of its genera and species, at each successive change in the climate and condition of the surface of the earth. This family forms about one three-hundredth part of the total number of existing vegetables.
Another family which has pervaded all the Series of formations, though in small proportions, is that of Palms.
The view we have taken, of the connexions be tween the extinct and living systems of the vegetable kingdom, supplies an extensive fund of
[523 CONNEXION WITH PHYSICO-THEOLOGY.] arguments, and lays open a new and large field of enquiry, both to the Physiologist, and to the student in Physico-Theology.
In the fossil Flora, we have not only the existing fundamental distinctions between Endogenous and Exogenous plants, but we have also agreement in time details of Structure, throughout numerous families, which indicates the influence of the same Laws, that regulate the development of the living members of the vegetable kingdom.
The remains of Fructification, also; found occasionally with the plants of all formations, shew still further, that the principles of vegetable Reproduction have at all times been the same.
The exquisite organizations which are disclosed by the microscope, in that which to the naked eye is but a log of Lignite, or lump of Coal, not only demonstrate the adaptation of means to ends, but the application also of similar means, to effect corresponding ends, throughout the several Creations which have modified the changing forms of vegetable life.
Such combinations of contrivances, varying with the varied conditions of the earth, not only prove the existence of a Designer from the existence of method, and design ; but from the Conflexion of parts, and Unity of purpose, which Pervade the entirety of one vast, and complex, but harmonious Whole, shew that One, and the same mind gave origin and efficacy to them all.