--- we see no

advance the proposition of a successive production of new species, when there is evidently no such law or fact to be found in nature. The idea of spontaneous production has long ago been scouted from science, and the no less illogical one of equivocal generation is fast going. We see no analogy in nature to lead us to suppose that such a law existsprovision for such operations, and no trace of such having ever occurred · we can predicate that the earth will produce certain plants after we have deposited certain seeds, but that if such seeds are carefully excluded, that no species of vegetation will follow-we can predicate that a lupin seed will produce a certain flower, followed by a seed similar to the parent one; and we may speculate freely on certain varieties of these, which circumstances may modify the production of, but we know to a certainty, from experience and analogy, that the lupin can never produce a rose, and that the soil alone will never bring forth a new species of plant.

It is fair to presume, then, that as the origination of species is unknown in nature, it does not exist. It is asserted that it does exist, but that the periods of its operation are at immensely distant intervals. This is a mere assertion, without proof by facts, and is contradicted by analogy; for the periods of germination and animal reproduction are all within limited cycles, depending on circumstances, which occur periodically, and which are apparent as contrivances in nature. The "recent introduction of man on the globe" has been given as an example of repeated acts of creation. But this is merely assuming as a fact a conjecture, of which we have no conclusive proof.

A reasoner of another school may say, that as organized beings were created at first, new species may be afterwards added by a special repeated act of the Creator. It may be answered, that we are told that organized beings were at first made by the Creator, but

we have no information of subsequent operations of a similar kind; and having no good grounds to prove it, the assumption of such after acts is illogical. For, suppose we were to assume the reverse proposition, — that the creation of organic beings was an act that was accomplished at once, under peculiar circumstances, and which it was impossible to repeat, this is just as tenable and irrefragable an argument as the other. It is astonishing on what flimsy grounds even such a mind as that of Blumenbach could speculate on this subject. Because the animalcule, called the vibrio aceti, is found only in stale vinegar, a substance produced by civilized man, this philosopher argues, that this being must have been of recent creation or origin. Yet a moment's reflection might have convinced this acute naturalist, that similar products to vinegar exist in nature, and must have existed from the beginning-as in sour grapes, a decaying sugar-cane, and every other vegetable with fermenting saccharine juices. We have entered more at large into this subject in a paper in the Edinburgh Journal of Natural and Geographical Science, vol. II.

1830.*

Linnæus conjectured that plants and animals originally radiated from a common centre in the tropical zone of the primitive earth, where the altitude of mountains produced that variety of climate suited to their different natures, and that thus a gradual diffusion took place over the whole earth.

A modification of some theory of this kind might be employed to explain the appearances of our fossiliferous strata, in opposition to that of successive creations, and may be thus exhibited in the following diagram :—

* We beg to state, that both here and in the text, we do not attempt to prove that successive creations of organized beings may not have taken place, but that hitherto we have no direct proofs of such.

d1, d2, d 3, d 4, Detrital matter formed in ancient seas, with animals and vegetables emanating from primary centre.

e, New continents subsequently elevated, forming the present land.

The successive circles, d, d, d, d, may indicate the several formations; d 4 being the first deposit in the depths of the ocean, and containing the remains of animals that formed the pioneers of the yet untenanted spaces around; d 3, d 2, d 1, representing the next orders in succession. To fill up this hypothetical sketch, we must suppose other centres formed contemporaneously, but under different modifications; and that repeated elevations of the marine strata took place, by which the ocean level, and other circumstances, were so altered as to interrupt the farther increase of the same species in the same localities, while at the period or periods when this ocean bed finally became dry land, the temperature was so changed as to admit of a more complete separation of genera and species, and their more varied dispersion over the globe.

NOTE V. p. 48.

The Burdiehouse limestone is an evident fresh water formation, situated below the Edinburgh coal-field, and belongs to the carboniferous limestone strata contiguous, . forming a partial and local deposit. Besides the ichthyological remains discovered and described by Dr Hibbert, (Edinburgh Philosophical Transactions, vol. xiil.) and enumerated in my Geological Sketch of the Environs of Edinburgh, I have since found several fragments of bones, which appear to me to belong to animals of a higher class than fishes, and probably to the class reptilia. One bone, five inches in length and four in breadth, has much the appearance of a coracoid bone of some unknown reptile.

The bones figured in the annexed plate are of the natural size, from a slab of the same limestone; the bone a is exactly the shape of the larger specimen in my possession. There are two similar ones in the same piece of limestone, and two the same as b. Both these latter are imperfect, but the fragments have a resemblance to scapular bones.

These bones differ from those of fishes in having a more compact structure, and a less fibrous appearance, in having well defined edges and furrows, marking out the situation of blood-vessels traversing their surface. The bodies c c are of frequent occurrence in this locality. They differ from the scales of the ganoid order of fishes, also abundantly found, resemble somewhat the scales of the cycloid order, but may be the dermal scales of some reptile.

I have also found two portions of jaw bones, with numerous small teeth, which are figured e, e, somewhat magnified; ƒ are the same still more magnified, and evidently resemble the teeth of a shark. These teeth are very numerous in the jaws, indicating the double and