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The same truth is exemplified if we turn to certain great periods of the earth's history as, for example, the Mesozoic epoch. There are groups of reptiles, such as the Ichthyosauria and the Plesiosauria, which appear shortly after the commencement of this epoch, and they occur in vast numbers.
Godwin Austin would say comes next, but probably rocks containing more ammonites, and more ichthyosauria and plesiosauria, with a vast number of other things; and under that I should meet with yet older rocks containing numbers of strange shells and fishes; and in thus passing from the surface to the lowest depths of the earth's crust, the forms of animal life and vegetable life which I should meet with in the successive beds would, looking at them broadly, be the more different the further that I went down.
The same truth is exemplified if we turn to certain great periods of the earth's history as, for example, the Mesozoic epoch. There are groups of reptiles, such as the Ichthyosauria and the Plesiosauria, which appear shortly after the commencement of this epoch, and they occur in vast numbers.
The ancestors of Terebratulina caput serpentis may have been present at a battle of Ichthyosauria in that part of the sea which, when the chalk was forming, flowed over the site of Hastings.
For if every species, without exception, has arisen by minute modifications, it seems incredible that a small percentage of such transitional forms should not have been preserved. This, of course, is especially the case as regards the marine Ichthyosauria and Plesiosauria, of which such numbers of remains have been discovered.
Or among the Teleostei in what respect is the Beryx of the Chalk more embryonic, or less differentiated, than Beryx lineatus of King George's Sound? Or to turn to the higher Vertebrata in what sense are the Liassic Chelonia inferior to those which now exist? How are the Cretaceous Ichthyosauria, Plesiosauria, or Pterosauria less embryonic, or more differentiated, species than those of the Lias?
But the number of forms represented by many individuals, yet by no transitional ones, is so great that only two or three can be selected as examples. Thus those remarkable fossil reptiles, the Ichthyosauria and Plesiosauria, extended, through the secondary period, probably over the greater part of the globe.
Or among the Teleostei in what respect is the Beryx of the Chalk more embryonic, or less differentiated, than Beryx lineatus of King George's Sound? Or to turn to the higher Vertebrata in what sense are the Liassic Chelonia inferior to those which now exist? How are the Cretaceous Ichthyosauria, Plesiosauria, or Pterosauria less embryonic, or more differentiated, species than those of the Lias?
Among Vertebrates there is no ordinally distinct fossil fish: there is only one extinct order of Amphibia the Labyrinthodonts; but there are at least four distinct orders of Reptilia, viz. the Ichthyosauria, Plesiosauria, Pterosauria, Dinosauria, and perhaps another or two.
How are the Cretaceous Ichthyosauria, Plesiosauria, or Pterosauria less embryonic, or more differentiated, species than those of the Lias? Or lastly, in what circumstance is the 'Phascolotherium' more embryonic, or of a more generalized type, than the modern Opossum; or a 'Lophiodon', or a 'Paleotherium', than a modern 'Tapirus' or 'Hyrax'?
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