the forms of primitive seas, and of elevated lands. In some cases these organised structures have been preserved perfect in the minutest details of tissues, integument, and articulated parts, whilst, in others, the animal passing over soft argillaceous mud, has left nothing but the traces of its course, or the remains of its undigested food, as in the coprolites. In the lower Jura formations (the lias of Lyme Regis), the ink bag of the sepia has been so wonderfully preserved, that the material, which myriads of years ago might have served the animal to conceal itself from its enemies, still * [In certain localities of the new red sandstone, in the valley of the Connecticut, numerous tridactyl markings have been occasionally observed on the surface of the slabs of stone when split asunder, in like manner as the ripple-marks appear on the successive layers of sandstone in Tilgate Forest. Some remarkably distinct impressions of this kind, at Turner's Falls (Massachusetts) happening to attract the attention of Dr. James Deane, of Greenfield, that sagacious observer was struck with their resemblance to the foot-marks left on the mud-banks of the adjacent river by the aquatic birds which had recently frequented the spot. The specimens collected were submitted to Professor G. Hitchcock, who followed up the inquiry with a zeal and success that have led to the most interesting results. No reasonable doubt now exists that the imprints in question have been produced by the tracks of bipeds impressed on the stone when in a soft state. The announcement of this extraordinary phenomenon was first made by Professor Hitchcock, in the American Journal of Science, (January, 1836,) and that eminent geologist has since published full descriptions of the different species of imprints which he has detected, in his splendid work on the geology of Massachusetts.-Mantell's Medals of Creation, vol. ii. p. 810. In the work of Dr. Mantell above referred to, there is, in vol. ii. p. 815, an admirable diagram of a slab from Turner's Falls, covered with numerous foot-marks of birds, indicating the track of ten or twelve individuals of different sizes.]-Tr. [From the examination of the fossils spoken of by geologists under the name of Coprolites, it is easy to determine the nature of the food of the animals, and some other points; and when, as happened occasionally, the animal was killed while the process of digestion was going on, the stomach and intestines being partly filled with half-digested food, and exhibiting the coprolites actually in situ, we can make out with certainty, not only the true nature of the food, but the proportionate size of the stomach, and the length and nature of the intestinal canal. Within the cavity of the rib of an extinct animal, the paleontologist thus finds recorded, in indelible characters, some of those hieroglyphics upon which he founds his history.-The Ancient World, by D. T. Ansted, 1847, p. 173.]—7r. T yields the colour with which its image may be drawn.* Ir other, strata again, nothing remains but the faint impression of a muscle-shell, but even this, if it belong to a main division of mollusca,† may serve to show the traveller, in some distant land, the nature of the rock in which it is found, and the organic remains with which it is associated. Its discovery gives the history of the country in which it occurs. The analytic study of primitive animal and vegetable life has taken a double direction; the one is purely morphological, and embraces, especially, the natural history and physiology of organisms, filling up the chasms in the series of still living species by the fossil structures of the primitive world. The second is more specially geognostic, considering fossil remains in their relations to the superposition and relative age of the sedimentary formations. The former has long predominated over the latter, and an imperfect and superficial comparison of fossil remains with existing species has led to errors, which may still be traced in the extraordinary names applied to certain natural bodies. It was sought to identify all fossil species with those still extant in the same manner as, in the sixteenth century, men were led by false analogies to compare the animals of the New Continent with * A discovery made by Miss Mary Anning, who was likewise the discoverer of the coprolites of fish. These coprolites, and the excrements of the ichthyosauri, have been found in such abundance in England (as for instance near Lyme Regis), that, according to Buckland's expression, they lie like potatoes scattered in the ground. See Buckland, Geology considered with reference to Natural Theology, vol. i. pp. 188-202 and 305. With respect to the hope expressed by Hooke "to raise a chronology" from the mere study of broken and fossilized shells "and to state the interval of time wherein such or such catastrophes. and mutations have happened," see his Posthumous Works, Lecture, Feb. 29, 1688. [Still more wonderful is the preservation of the substance of the animal of certain cephalopods in the Oxford clay. In some specimens recently obtained, and described by Professor Owen, not only the inkbag, but the muscular mantle, the head, and its crown of arms, are all preserved in connection with the belemnite shell, while one specimen exhibits the large eyes and the funnel of the animal, and the remains of two fins, in addition to the shell and the ink-bag. See Ansted's Ancient World, p. 147.]—Tr. Leop. von Buch, in the Abhandlungen der Akad. der Wi88. zu Berlin in dem J. 1837, s. 64. those of the old. Peter Camper, Sömmering, and Blunien bach, had the merit of being the first, by the scientific application of a more accurate comparative anatomy, to throw light on the osteological branch of paleontology-the archaology of organic life; but the actual geognostic views of the doctrine of fossil remains, the felicitous combination of the zoological character with the order of succession, and the relative ages of strata, are due to the labours of George Cuvier, and Alexander Brongniart. The ancient sedimentary formations, and those of transition rocks, exhibit, in the organic remains contained within them, a mixture of structures very variously situated on the scale of progressively developed organisms. These strata contain but few plants, as, for instance, some species of Fuci, Lycopodiacea which were probably arborescent, Equisetaceæ, and tropical ferns; they present, however, a singular association of animal forms, consisting of Crustacea (Trilobites with reticulated eyes, and Calymene), Brachiopoda (Spirifer, Orthis), elegant Sphæronites, nearly allied to the Crinoidea,* Orthoceratites, of the family of the Cephalopoda, corals, and blended with these low organisms, fishes of the most singular forms, imbedded in the upper silurian formations. The family of the Cephalaspides, whose fragments of the species Pterichtys were long held to be Trilobites, belongs exclusively to the Devonian period, (the Old Red); manifesting, according to Agassiz, as peculiar a type amongst fishes as do the Ichthyosauri and Plesiosauri amongst reptiles. The Goniatites, of the tribe of Ammonites,‡ are manifested in the transition chalk, in the greywacke of the devonian periods, and even in the latest silurian formations. The dependence of physiological gradation upon the age of the formations, which has not hitherto been shown with perfect certainty in the case of invertebrata,§ is most regularly * Leop. von Buch, Gebirgsformationen von Russland, 1840, s. 24-40. + Agassiz, Monographie des Poissons fossiles du vieux Grès Rouge, p. vi. and 4. Leop. von Buch, in the Abhandl. der Berl. Akad., 1838, s. 149168; Beyrich, Beitr. zur Kenntniss des Rheinischen Uebergangsgebirges, 1837, s. 45. § Agassiz, Recherches sur les Poissons fossiles, t. i. Introd. p. xviii Davy, Consolation in Travel, dial. iii. manifested in vertebrated animals. The most ancient of these, as we have already seen, are fishes; next in the order of succession of formation, passing from the lower to the upper, come reptiles and mammalia. The first reptile (a Saurian, the Monitor of Cuvier), which excited the attention of Leibnitz,* is found in cuperiferous schist of the Zechstein of Thuringia; the Palæosaurus and Thecodontosaurus of Bristol are, according to Murchison, of the same age. The Saurians are found in large numbers in the muschelkalk,† in the keuper, and in the oolitic formations, where they are the most numerous. At the period of these formations there existed Plesiosauri, having long swan-like necks consisting of thirty vertebræ; Megalosauri, monsters resembling the crocodile, forty-five feet in length, and having feet whose bones were like those of terrestrial mammalia, eight species of large-eyed Ichthyosauri, the Geosaurus or Lacerta gigantea of Sömmering, and finally, seven remarkable species of Pterodactyles,‡ or Saurians furnished with membranous wings. In the chalk the number of the crocodilial Saurians diminishes, although this epoch is characterised by the socalled Crocodile of Maestricht, (the Mososaurus of Conybeare), and the colossal, probably graminivorous Iguanodon. Cuvier has found animals belonging to the existing families of the crocodile in the tertiary formation, and Scheuchzer's antediluvian man (homo diluvii testis), a large salamander allied to the Axolotl, which I brought with me from the large * A Protosaurus, according to Hermann von Meyer. The rib of a Saurian asserted to have been found in the mountain limestone (carbonate of lime) of Northumberland (Herm. von Meyer, Palæologica, s. 299), is regarded by Lyell (Geology, 1832, vol. i. p. 148) as very doubtful. The discoverer himself referred it to the alluvial strata which cover the mountain limestone. ✦ F. von Alberti, Monographie des Bunten Sandsteins, Muschelkalks und Keupers, 1834, s. 119 und 314. See Hermann von Meyer's ingenious considerations regarding the organization of the flying Saurians, in his Palæologica, s. 228–252. In the fossil specimen of the Pterodactylus crassirostris, which, as well as the longer known P. longirostris (Ornithocephalus of Sömmering), was found at Solenhofen, in the lithographic slate of the upper Jura formation, Professor Goldfuss has even discovered traces of the membranous wing, "with the impressions of curling tufts of hair, in some places & full inch in length." Mexican lakes, belongs to the most recent fresh-water formations of Eningen.* The determination of the relative ages of organisms by the superposition of the strata has led to important results regarding the relations which have been discovered between extinct families and species, (the latter being but few in number) and those which still exist. Ancient and modern observations concur in showing that the fossil floras and faunas differ more from the present vegetable and animal forms in proportion as they belong to lower, that is, more ancient sedimentary formations. The numerical relations first deduced by Cuvier from the great pheonomena of the metamorphism of organic life,† have led, through the admirable labours of Deshayes and Lyell, to the most marked results, especially with reference to the different groups of the tertiary formations, which contain a considerable number of accurately investigated structures. Agassiz, who has examined 1700 species of fossil fishes, and who estimates the number of living species which have either been described or are preserved in museums, as 8000, expressly says, in his masterly work, that "with the exception of a few small fossil fishes peculiar to the argillaceous geodes of Greenland, he has not found any animal of this class, in all the transition, secondary or tertiary formations, which is specifically identical with any still extant fish." He subjoins the important observation "that in the lower tertiary formations, for instance, in the coarse granular calcareous beds, and in the London clay, onethird of the fossil fishes belong to wholly extinct families. Not a single species of a still extant family is to be found under the chalk; whilst the remarkable family of the Sauroidi (fishes with enamelled scales), almost allied to reptiles, and which are found from the coal beds--in which the larger species lie to the chalk, where they occur individually, bear the same relation to the two families, (the Lepidosteus and Polypterus,) which inhabit the American rivers and the Nile, [Ansted's Ancient World, p. 56.]—Tr. + Cuvier, Recherches sur les Ossemens fossiles, t. i. pp. 52–57. See also the geological scale of epochs in Phillips' Geology, 1837, pp. 166– 185. See Wonders of Geology, vol. d. 2301-Tr |