1. The deposition of stratified rocks. 2. The changes of organic life on the land and in the sea. 3. The displacements of land, and changes of physical geography. The phenomena of stratification are at this day repeated, and on a very considerable scale, in most parts of the world. Where great rivers sweep earthy materials and vegetable reliquiæ to the sea, as in the case of the Mississippi, Amazonas, Rhine, the Po, and other rivers, littoral aggregations take place, and new land is formed; tides and currents throw up sand-banks, or disperse the finer sediment far from the shore over the quiet bed of the ocean. From the growth of new land on the Adriatic and Egyptian coasts, by the action of the Po and the Nile, some notion may be formed of the great quantity of sediment annually transported by rivers to the sea, and both reason and experience show that the materials are there accumulated in the same manner as the ancient strata were. Hence it is very obvious that any conclusions as to time, drawn from the mere number of species which were developed and destroyed with any system of strata, will be totally opposed to others based on the observed thickness of the strata. The inferences are obvious and important; the numerical relations of organic life to the amount of stratified deposits are variable; one cannot be used as a measure of the other; the variety and abundance of organic life has been augmenting from the primary to the tertiary eras, or the deposition of strata was in the early ages of the world fifty times as rapid as in the tertiary period. This latter conclusion can never be allowed, since the fossiliferous primaries show clearly their origin from landfloods and littoral currents, and these depend on influences which cannot be supposed to have varied in any such proportion. It thus appears that neither the numbers of organic fossils nor the thicknesses of strata afford a perfectly satisfactory scale by which to measure past geological time; but whichever of them be preferred, the age of the world cannot be estimated at less than several times the whole tertiary period, and compared with this the historical portion of time, which dates from the birth of man, contracts to a point. By uniting the two considerations above stated, it will appear certain that the rate of organic development has been augmented, and probable that the rapidity of sedimentary deposition diminished since the primary era; and it is no slight argument in favour of the hypothesis of a gradually cooling globe, that both these phenomena are natural consequences of it-for that the greater influence of the earth's proper heat in the earlier epochs would favour the mechanical but limit the vital activity of nature seems to require no proof. If however independent proof were required of this change of ratio among the agencies of nature, we must appeal to a third order of phenomena most certainly characteristic of disturbances of the equilibrium of the earth's proper temperature: the fractures, contortions, and other marks of the violent elevation and depression of the crust of the globe. From what has been already stated it is very clear that the principal phenomena of this description occurred specially at particular intervals during the long periods of geology; for example, after the primary period, after the carboniferous era, before and after the accumulation of the cretaceous strata, after many of the tertiaries were produced. Now, on comparing the amount of disturbance effected at these epochs respectively, we are unable to perceive that the efficient causes have diminished in force; for the elevation of the Alps in the tertiary period is apparently quite as conspicuous a phenomenon as can be found among older geological monuments. M. Elie de Beaumont, to whose speculation as to the geographical characters of subterranean movements allusion has already been made, supposes that as many as twelve distinct epochs of mountainelevation may be recognised. The following is a brief summary of the classification which best suits the geology of England : But are they now accumulated with the same, with greater, or less rapidity? If equal deposits are now formed in equal times, the calculation of the age of the visible crust of the earth is as easy as it would be philosophically useless; but to assume this principle is to nullify the conclusion from it. Unless it can be shown, à priori, that atmospheric influence must have been constant through all past geological time, the assumption will not be accepted. This cannot be satisfactorily shown, for the external excitants on which the atmospheric actions depend contain variable elements. No certain conclusion then can be rested on the comparison of the mere thickness of the stratified rocks, as to the lapse of time, unless there can be found an independent scale of time which may help to interpret the other. Such a scale of time is perhaps contained in the series of organic beings imbedded in the earth. These belong to many successive systems of life, which may be compared with the existing forms of nature, and could we establish from history any rate of change in organic life, any per-centage of species destroyed, or created in a given series of years, some considerable steps might be laid for further advance. But two or three thousand years appear to have made no change on quadrupeds, birds, reptiles, fishes, shells, or conspicuous plants. As far as can be known by study of old writers on natural history, sculptured monuments, coins, and mummies, no change of external form or internal structure has been experienced since the earliest historical era; the loss of a very few species is all that can be safely admitted; and no proof is offered of a single newly-created form, though the distribution of the different groups of plants and animals has been varied by sea-currents carrying seeds and ova, and altered by man, who has learned to conquer by obeying nature. As far therefore as the more obvious and characteristic forms of animals and plants can be admitted to yield satisfactory evidence, the period of two thousand years since the days of Aristotle would be insufficient even as a unit of measure by which to estimate the intervals of geological time which elapsed during the deposition of strata. This conclusion is strengthened by some and weakened by other considerations. It is weakened by the circumstance that the changes of organic life appear to have been sudden; it is fortified and illustrated in a powerful degree by comparing existing nature with the tertiary era, for thus the ten or more thousand shells of this day appear to be joined to an equal number of others, into one long series of definite organic forms, which, since the date of the chalk, have admitted new and lost old species continually. Whether these new species, in any particular basin of strata, were parts of one or more new creations there, or, as may perhaps be thought probable, transferred from other centres of oceanic life, is quite *4. After the deposition unimportant for the argument as to time. The effects resemble those noticed among the older strata, the causes must be assumed to be correspondingly similar, and the times must be in some degree proportionate. Uniting therefore the tertiary and modern eras into one great geological period, we may compare the unknown quantity of time which it includes with other equally unknown and older intervals in the history of the globe, corresponding to similarly complete series of organic forms. This comparison is facilitated by the remarkable fact of the almost total distinctness of the organic beings of successive geological periods. Had the shells of successive systems of strata been gradually changed by substitution, we should have been compelled to compare not systems but formations, or even individual strata; and the conclusions might have become irremediably obscure. The systems to be compared are:-Tertiary, Cretaceous, Oolitic, Saliferous, Carboniferous, Fossiliferous, and Primary. The following table, extracted from Professor Phillips's 'Guide to Geology,' gives the proportionate thickness and number of organic forms of these systems : Geological Period. 1. After the deposition *3. After all the primary Conglomerate of the coal strata. Conglomerates follow in the red-sandstone. 5. After the oolitic pe- *6. After the London Anticlinal axes and ver- Isle of Wight, Axis of At the three epochs marked by stars, the most considerable movements and greatest changes in physical geography appear to have been produced. Such changes also occurred about the same epochs on the continent of Europe: the most universal of the phenomena seem to be the two earlier ones; but it is almost impossible in any case to prove that the occurrence of convulsions was synchronous at distant points. Since then we can neither affirm anything with respect to the change of force of the subterranean monuments at different geological epochs, nor can ascertain, except by reference to the phenomena of stratification and organic life, whether they occurred more frequently in one period than another, it is impossible to draw from the evidence of these disruptions any certain conclusion either as to the change of the earth's proper heat or the extent of geological time. If indeed the actual effects of earthquakes were to be placed against the mighty wall of the Penine fault, the vertical beds of the Isle of Wight, or the concealed dislocation of the coal-fields of Valen3 s ciennes, there would be no doubt of the decay of natural agencies; but this is not allowable, for the great dislocations alluded to are to be viewed as phenomena of a short interval of violent movements between long periods of ordinary action such as now obtains on the globe. It may be supposed that the number of these cases of very great and extensive disturbance is in proportion to the time elapsed; but as none such has occurred within the reach of history for at least 4000 years, we see how very ancient is the earth; and further, we have no data for accurately computing in numbers the vast periods which have elapsed in producing the stratified crust changing many times its vegetable and animal races. On the whole, it appears that the day is not arrived for theory to trust itself with the attempt to assign definite values to the symbols of duration which remain in the earth. Long, undoubtedly, perhaps as long as the periods which the study of planetary motions has revealed, must be the whole range of geological time; but until we know at this day what is the average rate of deposition of sediment in the sea, or the usual age of marine Mollusca, until we can determine the numerical or structural relations between organic forms and physical conditions, or can convert the irregular effects of volcanic fires into a calculable series of changes of temperature, there is little hope that the invitation of the Royal Society, to assign the antiquity of the crust of the earth, will be accepted by prudent and competent geologists. Economical Applications of Geological Science.-"Practice," says Professor Whewell, "has ever been the nurse of theory: art has ever been the mother of science, the comely and busy mother of a daughter of far higher and serener beauty. But the benefits are reciprocal; geology, at least, is capable of well repaying the large debt which it owes to the experience of the miner, the engineer, and the agriculturist, and indeed some of its truths are already largely productive of public benefit. "There is hardly a district in this island where the reasoning of geology has not checked extravagent expenditure in search of coal or metallic ores where such are not to be found, and conquered the credulity of ignorance ever ready to listen to the delusive and almost superstitious notions of merely working colliers and miners. The false and deceitful promise of finding good coal by going deeper, will not often again lure the landed gentry and respectable companies to such adventures as sinking for coal in the oolites of Oxford, the sandstones of Sussex, or the silurians of Radnorshire. But it is not merely by preventing foolish and wasteful expenditure, in search of imaginary treasures, that geology has aided the mining interest: it is within our memory that the eminent practical men of the great northern coal-fields doubted or denied even the existence of coal under the magnesian limestone. Yet now the Hetton colliery, and (in consequence of Dr. William Smith's geological opinions) the South Hetton colliery, send enormous quantities of excellent coal to the London market from beneath the dreaded magnesian limestone. The almost universal prejudice of colliers that 'Red rock cuts off coal,' has been vanquished in Lancashire, Staffordshire, and Somersetshire, and reasons have been given by Conybeare and others for believing that under the red rocks of the midland counties great tracts of coal remain for the public advantage and the triumph of geology." ('Phil. Mag. and Annals.') Some years ago, Lord Dartmouth, guided by geological reasoning, in opposition to the views of the local colliers, sunk a trial pit for coal near Birmingham, and found it below red-sandstone rocks. It was faulty near the pit bottom; but this has not prevented the establishment of a colliery, nor discouraged further attempts in the vicinity. Coal-working. In the practical department of coal-working, geology can as yet render little aid, because the experience of the coal districts has hardly yet been turned into science. The subject of the 'faults' ('troubles,' as they are often and justly called), from which no coalfield is exempt, and which by their effects on subterranean drainage, and the disarrangement of the subterranean works, their influence on the quality of the coal, and other circumstances, are of the highest importance to the collier, is yet almost wholly unknown as a branch of science. One general fact known concerning them (the correspondence of the dip of the fault to the depression of the strata), may be illustrated in the subjoined diagram after Professor Phillips's. Fig. 8. 8 In this figure the faults a, b, and x, decline variously from the horizon h h'; and they are most frequently found to dip or decline under that portion of the divided strata which is relatively depressed, as a and b, not as x, which represents a rare and exceptional case. By the sides of faults the strata are often slightly or considerably bent, sometimes in the direction tending to unite their disrupted parts, as a; sometimes in the contrary way, as b. In the former case they | are said to 'rise to an upthrow, and dip to a downthrow;' in the latter they 'rise to a downthrow, and dip to an upthrow.' If these circumstances were carefully recorded by surveyors of collieries, science might eventually combine the detached facts into general laws, show their dependence on other conditions, and thus put an instrument of discovery into the hands of practical men. It is a common thing to find valuable coal-beds at first injured, and ultimately rendered worthless, by the interposition of a wedge or band of rock, r, in some part of the thickness of the coal; thus the Fig. 9. High Main Coal of Newcastle is split, and in a particular direction ruined by the 'Heworth Band.' The upper part of the Great Staffordshire coal-beds goes off in the Flying Reed;' and the ten-feet bed of Barnsley in Yorkshire divides into almost unknown parts. If the details of colliery working were more completely recorded, the law of these phenomena could be more accurately traced, so as to answer the anxious questions which such intrusive band suggest to coal proprietors. The variations of quality in coal, whether of different beds in the same district (a common case), or of the same beds in different districts (as in South Wales, where good furnace coal is found in the east, and antharcitic coal abounds in the west), are not now known in a scientific form; and therefore science can give no help to practice. Nothing but the union of the parties interested in coal-working can furnish the data necessary for the establishment of general rules. [COAL-FORMATION.] The beneficial results which mining operations have derived from geology are in proportion to the degree in which the experience of miners has been reduced to the form of science. On the subject of the situation of metallic treasures, already enough is known to show that the occurrence of mineral veins is a circumstance depending on conditions which are more or less ascertainable. For example, there is not, and perhaps has never been, in the British Isles, a single mine of any metal worked in any stratum more recent than the magnesian limestone; it is a general truth that rich veins of lead, copper, tin, &c., abound only in and near to districts which have been greatly shaken by subterranean movement; in Derbyshire, Alston Moor, Flintshire, and, in particular tracts, especially Cornwall and Devon, it is very apparent that near the great masses of granitic rocks the veins are most richly filled. The same facts are almost equally true on the continent of Europe, and in other parts of the world, though, occasionally, as in the Pyrenees, Auvergne, &c., the presence of igneous rocks may cause the exhibition of mineral veins in strata more recent than any of those which in England yield metallic ores. In all cases where new mining ground is to be attempted, rules such as those above noticed are valuable; but even in districts partially known, or long worked, many problems occur which time and combined registration of phenomena observed might easily solve. These geological problems, as to the relation between the contents of a vein and the nature of the neighbouring rock, the occurrence of certain_cross-veins, the depth of the workings, &c., usually present themselves to the practical miner under the general question of the probability of the vein being productive, and though the mining experience of 2000 years has been found insufficient to answer it, there appears no reason to doubt that it is capable of solution by the progress of geology. It is known that in a country of limestone, gritstone, and shale, equally broken by the same fissures, the former is generally most productive of lead (Alston Moor); that certain porphyritic rocks in Cornwall and Saxony appear directly influential on the deposits of particular metals; that argentiferous lead ore is more frequent in primary than in secondary strata; salts of lead more plentiful in the upper parts of veins (Lead Hills, Caldbeck Fells); but the precise nature of the connection of the phenomena is yet a desideratum, and it will be long ere the dim and wavering light of experience can be replaced by the steady beams of the torch of science. In the recent discoveries of gold in California and Australia we have an instance in which geological knowledge pointed successfully to these districts as being likely to contain the precious metal. [MINERAL VEINS.] In planning the lines of railways, canals, or common roads, the engineer will often be benefited by the records of geological surveys. In looking at the geological map of England, for example, it must be evident to any one acquainted with the geographical characters of the different formations, that no canal can be made from London to the western or north-western counties without a tunnel or summit level on the chalk hills (as at the Kennet and Avon, between Wilton and Devizes, and on the Grand Junction, at Tring). The oolitic range of hills, with its basis of lias, presents a similar and parallel obstacle, conquered by tunnels on the Thames and Severn at Shepperton, the Oxford Canal at Claydon, the Grand Junction at Braunston and Blisworth. Since then these and other ranges of hills compel the formation of summit levels and tunnels, it is of importance that the whole of a country should be known to the engineer, as to its mineral structure as well as its elevation, in order that the situation of these may be properly fixed. It was inconvenient to make the Thames and Severn tunnel at its present level, often much above the level of the spring which is called the source of the Thames, and in the thirsty oolitic rocks; for thus the cost of maintaining the supply of water by puddling the canal, and engines for pumping, has been found very oppressive. Tunnels and summit levels for canals should certainly be made in argillaceous rocks, and geological investigations will often point out situations where, from particular displacements of the rocks, this is practicable, even in a range of hills so continuous and so calcareous as the chalk or the oolites. The same rules do not apply to railroads, which, on the contrary, may often be beneficially carried through dry rocky hills which would absorb all the water of a canal. In the execution of the works of canals and railroads, a good geological map would often be found more serviceable as a guide to the engineer than a great number of borings, unless these were placed in situations corresponding to the variations of the strata, which such a map would indicate. In some favoured countries the labours of the sculptor and the architect are scarcely injured by exposure to the atmosphere for 2000 years; while in our damp and changeable climate even the interiors of cathedrals show, by the decay of their marbles and the destruction of the stone walls, the necessity for an architect to study the durability of his materials. It is remarkable that the Romans were more prudent or more fortunate in their choice of stone for buildings in Bath and York than their successors have been. The relics in the Institution at Bath abundantly prove that the rag beds of the oolite are more durable than the finer and handsomer freestone which the enterprise of Allen first introduced to common use. The magnesian limestone in the Roman walls of York is in far better condition of preservation than most of that which is of only half the age in the face of the cathedral. The Saxons in the north of England used the coarse and durable millstone-grit, which on the brows of the high mountains of Derbyshire and Yorkshire stands conspicuous for its bold defiance to the elements. In choosing from any given rock the parts which are most fitted for permanent edifices, the examination of nature is perhaps more instructive than even a study of buildings. Not every sort of water exists in the deeper parts of the earth, and in fact fills the whole space left by fissures in the rocks, unless where, as in diagram, fig. 10, there be a fault which breaks the continuity of the communications along the rocks. At the surface there will be generally one or more springs (2) along the line of such fault, F. In sinking deep pits it is generally found that argillaceous strata are quite dry within; for example, in the diagram above referred to, the well a, supposed to be sunk in the London clay, yields no water; but the other strata, alternating with the clays, yield water in greater or less quantity, and of quality corresponding with the nature of the rock. Thus the well b, sunk down to the sands, lignites, &c., of the plastic clay, yields some water, not always of good quality; but when the well, as c, is made to reach to and penetrate the chalk, a great body of good water commonly rises from that rock. [WATER; ARTESIAN WELL, in ARTS AND SC. Div.] To drain land is to intercept the natural springs: this can never be done upon good principles unless the geological structure of the district be known. When porous rocks alternate with strata impervious to water, the springs will commonly issue at several points on the surface-line of junction of the strata, as at x and y in diagram, fig. 10; and by making a deep drain along the line of junction, Dr. Smith has often accomplished the complete desiccation of wet lands in the oolitic districts of England, which had been in vain guttered in all directions by the usual hollow drains. The same principle applies, but not with the same ease of success, to the draining of districts where gravel and clay are much intermingled. The gravel acts as a porous rock, but its irregular distribution renders the operation of deep draining costly and less effectual. From the same principles it follows that springs may be regulated, and the subterranean reservoirs employed to store up water in the winter, when it is little wanted, for the purpose of supplying the demand in summer. This has actually been done by Dr. W. Smith, who opened, in the sandstone rocks near Scarborough, a subterranean reservoir on the site of a little spring, closed it with a dam, and regulated the discharge for the benefit of the town. [WATER] (Lyell, Principles of Geology; Lyell, Elementary Geology; Ansted, Geology, Introductory, Descriptive, and Practical; Ansted, Elementary Course of Geology; Phillips, Guide to Geology; Jukes, Popular Physical Geology; De la Beche, How to Observe in Geology; Portlock, A Rudimentary Treatise on Geology.) [See SUPPLEMENT.] a, b, c, wells; L, London clav; P, plastic clay and sands; C, chalk; 9, gault; G, lower greensand; W, wealden; x, y, z, springs; the last at a fault, F. granite resists the carbonic acid and moisture of the air; but while the rolled blocks from Shap-Fell retain, after thousands of years' exposure on the surface, their surfaces of attrition, the granitic top of Castle Abhol, in Arran, is so rotten that it may be easily beaten to fragments by a hammer. The millstone-grit of Brimham is almost wasted away over a hundred acres, while that of Agra Crags appears to be more capable of withstanding the same agencies; and the Druidical stones of Boroughbridge have stood the storms of 2000 years, with little more injury than a few rain-channels which scarcely reach the ground. To the agriculturist geology has rendered some services, and probably may in future be appealed to for further aid. Lister's proposal for the construction of a map of soils was only partially executed, after a century, in some of the county reports made to the Board of Agriculture. The principal use, as it appears to us, of such a map (and this is in fact supplied by the maps of strata), is to aid the statistics of agriculture by furnishing a basis for comparing the agricultural practices on similar and dissimilar soils. But geological science will appear more intimately connected with agricultural improvements if we consider it as the basis of all sound knowledge of springs and the subterranean distribution of water. The rain which falls from the heavens upon all soils and rocks indifferently, runs off the clays, but sinks into the limestones, sandstones, and other rocks, whose open joints act like so many hidden reservoirs. Owing to the complicated intercommunication of the fissures, these reservoirs are slowly filled and slowly emptied; both the supply from rain and the discharge from springs may and generally do go on together; and the jointed rocks may be viewed as equalising the supply and expenditure. But below the level of the springs thus formed, a great body of GEOMALACUS (Allman) a genus of Molluscous Animals belonging to the family Limacide. [LIMACIDE.] GEOMYS. [MURIDE.] GE'OPHILA (from y, the earth, and pλ, love), a genus of Plants belonging to the natural order Cinchonaceae. It has the limb of the calyx 5-parted, with linear spreading segments; the corolla tubular, with a pilose throat and 5 rather recurved lobes, with 5 anthers inclosed; the stigma bifid; the berry ovoid, angular, crowned by the calyx, 2-celled, 2-seeded. The species are creeping herbaceous plants with stalked cordate leaves, like those of a violet; the stipules are solitary, undivided; the flowers sub-sessile, umbellate, surrounded by bracts, which are shorter than the flowers. G. reniformis has the petioles hairy above; reniform obtuse leaves, with the lobes at the base approximate; the bracts linear; the peduncles 4-6-flowered, shorter than the leaves. It is a native of moist shady places in the hotter parts of America, as Havanna, Jamaica, Puerto Rico, Brazil, and the basin of the Orinoco. The root of this plant is emetic, and may be used with advantage as a substitute for ipecacuanha. G. violacea has cordate reniform leaves, obtuse, glabrous, with the lobes approximate at the base; petioles hairy above; umbels fewflowered, almost sessile between the ultimate pair of leaves; bracts linear-lanceolate. It is a native of Guyana, in woods, and of the Isthmus of Panama. It differs from G. reniformis by the petioles being shorter, the umbels hardly pedunculate, the corollas violaceous, and the berries blue. There are several other species of this genus, all of which were formerly referred to the genus Psychotria. They are G. diversifolia, G. violafolia, G. macropoda, and G. gracilis. GEOPHILUS. [COLUMBIDE.] GEORGINA, a name sometimes given to the Dahlia, but improperly. GEO'RYCHUS, Illiger's name for the Lemmings of Cuvier. [MURIDE.] GEOSAURUS, Cuvier's name for a sub-genus of Saurians, found in a fossil state only, and considered by him as intermediate between the Crocodiles and the Monitors. The remains of this animal were first obtained from the white lias at Monheim, in Franconia, by Sömmering, and named by him Lacerta gigantea. In a paper in the Nova Acta physico-medica Academiæ Cæsarea Leopoldino-Carolina Naturæ Curiosorum,' Dr. Ritgen has proposed a new name for this with several other fossil animals. On this paper a writer in the 'Zoological Journal' has the following remarks:-"The first of Dr. Ritgen's animals is the Lacerta gigantea of Sömmering, Mosasaurus of Conybeare and Parkinson, for which Dr. Ritgen, without assigning a single reason for the change of name, is pleased to adopt the more than sesquipedalian title of Halilimnosaurus crocodiloides. This appellation however may serve, in some degree, to explain his views of its affinities and original habitation, inasmuch as it shows that he regards it as a lacertine animal resembling a crocodile and inhabiting salt-water marshes, intermediate therefore between the extinct Enaliosauri, or Sea-Lizards, and the living Crocodiles of fresh-water streams. It is, moreover, the Geosaurus of Cuvier's Ossemens Fossiles.' There is some little obscurity here, which we will endeavour to dispel. That Cuvier's name, Geosaurus, should be retained according to the laws of nomenclature, there can be no doubt; and it appears that this provisional name was given, not in reference to the habits of the extinct lizard, but, to use Cuvier's own words ('par allusion à Terre, mère des Géans')-by an allusion to Terra, the Earth-Ge (F) of the Greeks, the fabled mother of the Giants. Indeed the sclerotic plates still remaining in the portion of the cranium figured by Cuvier in his 'Ossemens Fossiles,' could not have escaped the observation of that acute zoologist (who was so eminently alive to the laws of co-existence), as indicating aquatic habits. That he considered it subgenerically different from Mosasaurus appears from the following observations: Immediately after the allusion to the origin of the name, Cuvier says, 'I cannot retain for it the epithet Giganteus (Je ne peux lui laisser l'épithète gigantesque); for, in the great genus Lacerta we have already the animal of Maestricht, or Mosasaurus, which greatly surpassed it, and there is also another (the Megalosaurus) which is very superior in size-(nous avons d'abord l'animal de Maestricht, ou Mosasaurus, que le surpasse de beaucoup, et nous allons en voir un autre-le Megalosaurus qui lui est aussi très supérieur).'" Again, in a note to the previous article in the 'Ossemens Fossiles,' on Mosasaurus :-" With regard to the fossil animal of Monheim (Geosaurus), which M. de Sömmering has also regarded as identical with that of Maestricht (Mosasaurus), we shall see in a succeeding article that it differs from the Maestricht animal in many respects. M. Hermann von Meyer, in his most useful work Palæologica zur Geschichte der Erde und ihrer Geschöpfe' (8vo. Frankfurt, 1832), widely separates the two sub-genera. The first, Geosaurus, he exemplifies by Geosaurus Sömmeringii, syn. Lacerta gigantea, Sömmering, Halilimnosaurus crocodiloides of Ritgen. The second, Mosasaurus, Conybeare, Saurochampsa, Wagler, he exemplifies by Mosasaurus Camperi, syn. M. Hofmanni, Lacerta gigantea, Sömmering, zum Theil (in part). In his 'System der Fossilen Saurier,' which fossil Saurians he divides into four sections, denoted by the letters A, B, C, and D, he places Geosaurus under section A-(Saurier mit Zehen ähnlich denen an den lebenden Sauriern), and Mosasaurus under section C-(Saurier mit flossartigen Gliedmassen)." The remains upon which Cuvier founded his sub-genus were found in the canton Meulenhardt, at the depth of 10 feet, and a few paces from the crocodile described by Cuvier (Gavial of Monheim and of Boll; 'Oss. Foss.' tom. v. pp. 120-125; Crocodilus priscus of Sömmering; Eolodon priscus of Hermann von Meyer), by the labourers Geosaurus Sömmeringii. (From Cuvier's figures.) a, b, part of the head, which has been compressed; some of the sclerotie plates are still left within the orbit, as seen in Fig. b; c, d, e, teeth which had preserved their hard shining brown enamel; f, g, vertebra; fexhibits a part of the column; near the last vertebræ are the remains of the pelvis and femora; 7, five vertebræ like the first of those in Fig. f. Fragments of ribs in disorder are seen near both sets. employed to work the mines of granular iron (fer en grains) which fills the fissures of the strata of calcareous schist. Sömmering, to whom the Count of Reysach gave these precious fragments, to use Cuvier's expression (for in consequence of the nature of the bed in which they were discovered they were not well preserved), published an accurate account of them in the 'Memoirs of Munich' for 1816, accompanied by a lithographic illustration, which Cuvier reduced, and published in his Ossemens Fossiles;' Sömmering however thought that the bones belonged to a young individual of the Maestricht animal (Mosasaurus.) The bones were nearly calcined. Near the remains of the Saurian were a flat ammonite 4 inches in width, a fragment of bluish shell, and a great quantity of small scales, which, according to Sömmering's conjecture, belonged either to fishes or perhaps to the animal itself, if it was a Monitor, or some other lizard with small scales. The localities given by Hermann von Meyer are the Flötz; Solenhofen slate (Schiefer von Solenhofen); and, with reference to another specimen (with a query), for which he refers to Dekay, 'Ann. of the Lyc. of New York,' vol. iii., the marl of the Greensand in New Jersey (Mergel des Grünsandes in New Jersey). The original specimens figured and described by Sömmering are now in the collection of the British Museum (Wall-case A. B., 'Mantell Fossils of the British Museum,' p. 175). GERANIACEAE, Cranesbills, a natural order of Exogenous Plants, consisting chiefly of herbaceous plants or shrubs. They have tumid stems separable at the points. The leaves are either opposite or alternate; in the latter case opposite the peduncles, with membranous stipules. The flowers are white, red, yellow, or purple. The sepals 5, persistent, ribbed, more or less unequal, with an imbricated æstivation, sometimes saccate or spurred at the base. The petals 5, seldom 4, in consequence of one being abortive, unguiculate, twisted in æstivation, equal or unequal, either hypogynous or perigynous. The stamens usually monadelphous, hypogynous, twice or thrice as many as the petals; some occasionally abortive. The ovary composed of 5 carpels, placed round a long awl-shaped torus or growing point, each 1-celled, 2-seeded; styles 5, cohering round the torus, and separable from it; ovules semianatropal, adhering to the torus. The fruit formed of five shells, cohering round a long beaked torus, each piece containing one seed, having a membranous pericarp, and terminated by an indurated style, which finally curls back from the base upwards, carrying the pericarp along with it. The seeds solitary, without albumen. The embryo curved and doubled up, the radicle pointing to the base of the cell; cotyledons foliaceous, convolute, and plaited. The long beak-like torus round which the carpels are arranged, and the presence of membranous stipules at joints which are usually tumid, are true marks of this order, and all plants not possessing these peculiarities must be excluded. Among them is a South American genus called Rhynchotheca, which has been even elevated into a natural order, but which, according to Lindley, is surely an oxalid without petals, for the beak observed in its fruit belongs to the carpels and not to the torus. It is clear that in this order the ovules do not spring from the margins of the carpellary leaves. The species, about 500 in number, are very unequally distributed over various parts of the world. A great proportion is found at the Cape of Good Hope, chiefly of the genus Pelargonium. Erodium and Geranium are chiefly natives of Europe, North America, and Northern Asia. Pelargonium is found in Australia. An astringent principle and an aromatic or resinous flavour are the characteristics of the order. Geranium and Erodium are used in medicine. Pelargonium is remarkable for its beautiful flowers; it is nevertheless astringent in its properties. The affinities of Geraniacea are with Balsaminacea, Oxalidaceae, and Tropaeolacea. (Lindley, Vegetable Kingdom.) Plants the type of the natural order Geraniaceae. The flowers have 5 petals and 5 sepals, 10 monadelphous stamens, alternately larger, and with glands at their base. There are 79 species of this genus enumerated, of which 13 are British; of these only two are applied to any useful or medicinal purpose. G. Robertianum has 2-flowered peduncles; obovate, entire, or slightly emarginate petals; very long glabrous claws; transversely wrinkled downy capsules, smooth seeds, ternate acuminate leaves, and stalked trifid inciso-pinnatifid leaflets. This plant has small bright crimson flowers, and is found on waste ground, walls, and banks in Great Britain, in Brazil, and Chili. The whole herb has a strong disagreeable smell, which is said to be a preventive against bugs. A decoction of the plant is recommended as likely to give relief in calculous cases. It contains tannin, and exerts an astringent action on the system, and is given to cattle in some diseases. G. maculatum, Spotted Cranesbill, has a rather angular stem covered with retrograde pubescence; 3-5-parted leaves with deeplytoothed lobes; obovate entire petals; the filaments of the stamens hardly ciliated at the base. This species is a native of North America, from Canada to North Carolina. The flowers are of a pale lilac colour. On account of the astringent nature of this plant, it is known in some parts of North America as Alum-Root, and is employed successfully as a remedy in dysentery among children, a disease very prevalent in the parts of the country where it grows. The tincture is recommended in cases of ulcerated sore-throat and soreness of the gums, &c. Dr. Bigelow discovered the presence of large proportions of tannin and gallic acid in this plant. The quantity of tannin appears to be greater than that of any other constituent. The other British species are: G. phacum has 2-flowered peduncles, roundish wedge-shaped petals, rather longer than the mucronate sepals; carpels hairy below, transversely wrinkled above; seeds punctate, striate. It is found in woods and thickets, rarely. G. nodosum has obcordate long petioles, awned sepals, even downy carpels; leaves 3- to 5-lobed, lobes ovate, acuminate, serrate. It is found in Cumberland and Hertfordshire. G. sylvaticum has 2-flowered peduncles, obovate slightly-notched long petals, awned sepals, dotted seeds, palmate 7-lobed leaves. The filaments of the stamens subulate, fruit-stalks erect. G. pratense has 2-flowered peduncles, the carpels even, hairy, the hairs spreading, glandular; seeds minutely reticulated; the filaments of the stamens filiform, with a triangular ovate base; the fruit-stalk deflexed. G. sanguineum has peduncles mostly single-flowered; carpels smooth, crowned with a few bristles; leaves nearly round, 7-lobed; stem diffuse, hairy-the hairs spreading horizontally. G. pyrenaicum has obcordate petals, twice as long as the mucronate sepals; claws densely ciliated; stem erect, villose. G. pusillum has bifid petioles, about equalling the mucronate sepals; claws slightly ciliated; carpels with adpressed hairs; seeds smooth; stem diffuse, downy. G. dissectum has smooth carpels with erect hairs, reticulated seeds; stem diffuse, hairy; leaves divided almost to the base, longer than the peduncles. G. columbinum has obovate emarginate petioles, ciliated claws; the carpels smooth, with a few minute scattered hairs; the peduncles longer than the leaves; pedicels very long. G. rotundifolium has spathulate petals, entire, obtuse, rather longer than the shortly-awned sepals; claws glabrous; carpels smooth, with spreading hairs; seeds reticulated. G. molle has oblong deeply-bifid petioles, ciliated claws; carpels transversely wrinkled, glabrous; seeds smooth; flowers small and purple. G. lucidum has obovate entire petals; claws glabrous, very long, nearly equalling the transversely rugose pyramidal calyx; carpels reticulated, triply keeled. G. tuberosum, a plant growing in the south of Europe, particularly in Italy and Silesia, is the yepávior of Dioscorides (iii. 121), and the Geranium tertium of Pliny (xxvi. 11). The hardy perennial kinds of Geranium are very beautiful plants, and well adapted for ornamental cultivation. They will thrive in any common garden soil with ordinary care. (Don, Dichlamydeous Plants; Babington, Manual of British Botany; Fraas, Synopsis Plantarum Flora Classicæ.) GERBILLUS. [MURIDE.] GERFALCON. [FALCONIDE.] GERMEN. [PISTIL.] GERMINATION, the first growth of a seed, the act by which it exchanges the condition of an embryo for that of a young plant. The embryo of a plant is folded up in the inside of a seed, and is either a short double cone on which two or more cotyledons are fixed, or a simple more or less cylindrical body having no apparent distinction between the cotyledons and the axis. [SEED.] It has moreover little other than a cellular organisation, very often not possessing a trace of the complicated vascular and tubular structure afterwards developed. The act of unfolding, breaking through the integuments of the seed, and acquiring a vascular and tubular as well as cellular organisation, is germination. When a seed is placed in a moist |