THE WONDERS OF GEOLOGY. LECTURE V. 1. The zoological character of the chalk. 2. Zoological character of the wealden. 3. Site of the country of the iguanodon. 4. Medial secondary formations. 5. The oolite, or Jura limestone. 6. Tabular view of the oolite and lias. 7. Geographical distribution of the oolite and lias. 8. Stonesfield slate. 9. Organic remains of the Stonesfield slate. 10. Fossil opossum of Stonesfield. 11. Wealden and Stonesfield fossils. 12. Lithographic slates of Pappenheim, Solenhofen, and Monheim. 13. Coal of the oolite. 14. Geographical distribution of the lias. 15. Organic remains of the oolite and lias. 16. State of fossilization. 17. Saliferous, or new red sandstone system. 18. Tabular view of the saliferous system. 19. Geographical distribution of the saliferous strata. 20. Cheltenham waters. 21. Rock-salt and brinesprings. 22. Magnesian limestone, or zechstein. 23. Conglomerates of the new red sandstone. 24. Organic remains of the saliferous strata. 25. The spiriferæ of the new red sandstone. 26. Impressions of the feet of animals on sandstone. 27. Reptiles. 28. Turtles. 29. Fossil turtles. 30. Crocodiles. 31. The ichthyosaurus. 32. The plesiosaurus. 33. Pterodactyles, or flying reptiles. 34. Fossil salamander. 35. Fossil reptiles allied to the lizards. 36. Review of the Age of reptiles. 37. Objections considered. 38. Concluding remarks. 1. THE ZOOLOGICAL CHARACTER OF THE CHALK. -The examination of the chalk and wealden has afforded a striking illustration, not only of the nature of oceanic and river deposits in general, but also of the condition of animated nature at the close of the geological epoch which comprises the secondary formations. It will therefore be interesting in this stage of our inquiry to note the development of animal life during that period. The ocean of the chalk appears to have possessed the principal existing marine types of organization; it teemed with many species of dog-fish, lamna, galeus, and other genera of the shark family-with fishes related to the chimera, salmon, smelt, pike, dory, and ray, together with many of genera now extinct. Nautili and other cephalopoda abounded, as in our tropical seas; and the family of echinodermata, or sea-urchins, was profusely developed : star-fish, encrinites, and other radiaria; crustacea allied to the crab, lobster, shrimp, and prawn; univalve and bivalve mollusca; all these leading divisions of marine existence inhabited its waters. And although we have proof that numerous genera now no more, together with others of excessive rarity in the present seas, then swarmed in prodigious numbers; and negative evidence that the cetacea, as the whale, porpoise, seal, &c. were not among its inhabitants; yet the varied forms of animal life whose presence in the ocean of the chalk is attested by their fossil remains, unquestionably establish that the sea presented the same general conditions, and bore the same relation with the atmosphere and with light, as at the present time. The most remarkable peculiarity in the zoological character of the chalk is presented in the class of reptiles. With the exception of a lizard belonging to the family of the Iguanida, which inhabits the sea off the coast of South America, turtles are the only known living marine reptiles; but the chalk ocean was not only peopled by chelonia, but also by two or more enormous saurians, for the mosæsaurus lived in the cretaceous seas; and the ichthyosaurus, and plesiosaurus, as will be shown hereafter, were unquestionably inhabitants of the deep. 2. ZOOLOGICAL CHARACTER OF THE WEALDEN. -During the wealden epoch the lakes and rivers were peopled by fishes, mollusca, and crustacea, which, though specifically distinct from the recent, presented the same principal types as now exist in fresh-water. The lacustrine and marsh plants, and the palms, tree-ferns, and cycadeæ, constitute a flora offering peculiar generic and specific characters, but resembling the usual forms of tropical vegetation. The fresh-water turtles, crocodiles, and wading-birds, are in accordance with the fauna of modern tropical regions; but the colossal reptiles,― the iguanodon, megalosaurus, and hylæosaurus,whose living analogues must be sought in the pigmy iguanas and monitors, constitute a zoological character altogether at variance with the existing economy of animated nature. Here, then, we have evidence of a country almost exclusively inhabited by enormous reptiles; for although the most delicate plants, leaves, and fruits, the fragile bones of birds, the epidermis, and even ligaments of brittle shells, are found, not a vestige of any mammiferous animal has been discovered. I forbear to comment in this place on this astounding fact, of which the We tertiary deposits afforded us no intimation. have now approached the Age of reptiles-that geological epoch in which the earth swarmed with enormous oviparous quadrupeds; and the sea, the lakes, and the rivers teemed with reptile forms. 3. SITE OF THE COUNTRY OF THE IGUANODON. -Before I proceed to the consideration of the secondary formations which are antecedent to the wealden, I would briefly consider the question relative to a difference of climate which our discoveries seem to imply. From what has been advanced it is natural to inquire, whether at the period of the wealden these latitudes enjoyed a tropical temperature-whether turtles, crocodiles, and gigantic reptiles, here flourished amid forests of tree-ferns and palms; or if the geographical situation of the country of the iguanodon was far distant from the area now occupied by its spoils ? I shall not venture to give a decided reply to this interrogation, but content myself with offering some remarks on the appearance of transport which the fossils of the wealden exhibit; for I may premise, that the state of the organic remains does not seem to warrant the assumption that the reptiles and terrestrial plants, like the zoophytes, mollusca, and fishes of the chalk, lived and died on the spots where their remains are found entombed. With the exception of the beds of river shells, of cyprides, and of equiseta, (which naturally affect a marshy soil,) all the remains bear marks of having been |