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perhaps, blown into these latter situations with Neuropterous and Coleopterous Insects, among the latter, Buprestidæ and Curculionidæ. In the Palæozoic ages are no Cycadaceæ; in the Neozoic no Lepidodendra; Ferns abound in several of the deposits in and above the Upper Devonian Strata.

In the lowest beds of the Lias and passage-beds from the Trias, Insects have been collected at the Cliffs of Aust, Westbury and Wainlode, and at several other places in the Vale of the Severn, probably blown into shallow salt water, a common circumstance on the coasts. Others occur more abundantly in the Vale of Wardour and Purbeck. The census of the fossil orders of Insects runs thus: Cænozoic... Coleoptera (Copris, Donacia, Harpalus,) in Pleisto

cene beds, at Mundsley, Norfolk. (In France most of the Orders of Insects are

found in freshwater beds at Aix in Provence). Mesozoic ... Purbeck beds, Coleoptera, Neuroptera, Ortho

ptera, Homoptera, Diptera. Oolite of Stonesfield, Coleoptera, Neuroptera. Lias of Severn Vale, Coleoptera, Neuroptera,

Orthoptera, Homoptera, Diptera. Palæozoic... Coal-formation, Coleoptera, Neuroptera.

Terrestrial Saurian Reptiles acquired extraordinary magnitude in the Oolitic period, and exhibit as high a grade of organization in Megalosaurus and Iguanodon as the aquatic Crocodilians, of the same ages, Teleosaurus, Steneosaurus, Cetiosaurus and their allies. The earliest traces of Land Saurians are those already alluded to as found in the Nova Scotia coalfield, one of which is supposed to be of Lacertian, the other of Ganocephalic affinity. Perhaps in regard to most of the Saurian fossils we may prudently wait for further information before confidently assigning them to marine, fluviatile, or terrestrial life. Ichthyosaurus is no doubt truly marine, Megalosaurus truly terrestrial; regarding many others we may reserve an opinion.

i Brodie, On Fossil Insects. Westwood has determined many of the orders and genera.

Of fossil birds our evidence is mostly in footsteps, sometimes, as in Connecticut' and near Hastings?, of such extraordinary magnitude as to match the stride of the Moa of New Zealand. In general the footprints are of the Cursorial order of Birds; marks of their movements are found in the sandy shores of the Permian, Triassic, and Oolitic Seas.

Mammalia of the Marsupial order appear to have the priority in time. The most ancient fossils of this kind yet traced are the small insectivorous teeth found in the Trias of Würtemburg Next

1 Hitchcock, Mem. American Academy, Vol. II.

Beckles, Journal of Geol. Soc. * Lyell, Elem. of Geol. p. 343.

come the Insectivora of Stonesfield, which in part belong to the Marsupialia', and one, the latest of the discoveries there, the Stereognathus Ooliticus, which belongs to an artiodactyloạs order?. Next come the Insectivora and Rodentia of Purbeck, also in part Marsupial. Then as far as yet discovered a blank follows; there is no Mammal known of the Cretaceous period, but the Tertiary Strata reveal several successive groups. The whole series stands thus, if we include more than the British Fauna:

Pleistocene and Pleiocene. Full series of orders of mammalia
Meiocene...Pachydermata and other families.
Eocene...... Pachydermatous prevail.
Purbeck ... Marsupial Insectivora, Rodentia.
Stonesfield..Marsupial Insectivora, Artiodactylous genus.
Trias.........Marsupial Insectivora.

ÀNTIQUITY OF THE EARTH.

Geologists have been much censured for vainly endeavouring to assign measures of time to the seemingly vague and shadowy ages of the Trilobites and Belemnites; nor have they escaped censure for countenancing speculations which assign to the human race a period very much longer than that hitherto adopted on historical grounds. They deserve no rebuke, however, for the endeavour to force their way into the citadel of natural truth, if they undertake the siege after a sufficient survey of the difficulties of the enterprise, which in this case are not slight. Let any one acquainted with the modern aspect of Astronomy, consider well the nature of that problem which, omitting all previous cosmical changes, would count the years since the planet became a terraqueous globe—let him then look at the Mosaic narrative, and be satisfied with the truth, that 'In the beginning God created the heavens and the Earth,' for no measures of time conceivable by man will reach back to that remote epoch in the history of our solar system. That, however, is the starting-point of physical geography, for then began the movements and changes in land, water, and air, which it is the business of geology to register and interpret. As already explained, the gift of life on this earth is limited by conditions within which alone it is possible: until these conditions were attained that is to say, arrived at in the pre-ordained course of nature—the earth might be well described by the words without form, and void.' For the rocky monuments of this period, which we have endeavoured

1 Buckland, Bridgewater Treatise and Owen, Brit. Foss. Mammalia.

2 See for the latest Classification of Mammalia the Rede Lecture by Prof. Owen, 1859.

3 The capital discovery of Mr Beckles.

to trace, the terms 'Azoic' and 'Hypozoic' have been suggested. Thus arises the second great epoch in geological chronology—the epoch of Life on the Earth -the starting-point of Palæontology. How shall we proceed to collect evidence which may bring that remote event into a scale of solar time? What natural phenomena can be found, so much alike in all past periods of time, and so related to years and cycles of years, as to be safely employed in estimating, not only the relative antiquity of the several races of plants and animals, but the absolute antiquity of the earliest inhabitants of the earth?

The Geological Scale of Time is founded on the series of the strata deposited in the ancient sea; if the forces tending to produce such deposits have always been productive of equal effects in equal times, the thicknesses of the strata are exact measures of the times; the thickness added in a certain historical time to the modern sea-bed, will bear the same proportion to the total thickness which has been added in geological time as the historical time ascertained to the geological time required. This view of the uniformity of natural effects, in the strict terms here assigned, is perhaps held by none of the followers of Hutton, however nearly some expressions of the eminent author of the Principles of Geology may seem to approach it. It cannot be

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