Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/243

 words, are common to two of the great divisions of geological time. The like is true of the Teleostean fish Beryx. Moreover it has been seen that Hyperodapedon is nearly allied to the living lizard Sphenodon, — as nearly, I am inclined to think, as to its Triassic congener Rhynchosaurus. And if this extraordinary form has persisted with so little modification from the Trias till now, why may it not have inhabited the dry land of the Permian, of the Carboniferous, or of the Devonian Epoch ?

In discussing the question of the age of the Elgin sandstones in years gone by, reflections of this nature led me always to admit the possibility that these problematical beds might be of Devonian age ; for Hyperodapedon, Stagonolepsis, and Telerpeton, though clearly allied to Triassic and Mesozoic genera, were distinct from them, and had no stronger affinities with Mesozoic Reptilia, than the Proterosauria have (which yet are Palaeozoic and not Mesozoic), or than some of the Labyrinthodonts of the Coal (e. g. Anthracosaurus) have with those of the Trias.

Even now that Hyperodapedon is distinctly determined to be a Triassic genus, the possibility that it may hereafter be discovered in Permian, Carboniferous, or even older rocks, remains an open question in my mind. Considerations of this kind should have their just weight when we attempt to form a judgment respecting the reptiliferous strata of the Karoo in South Africa, and of Maledi and elsewhere in India,

In India, Hyperodapedon occurs associated with Labyrinthodonts, with Thecodont reptiles (some of which have Crocodilian characters), and with Dicynodonts.

In South Africa, Hyperodapedon has not yet been discovered ; but Labyrinthodont and Thecodont Reptilia (some of them Crocodiliform) have been found, and, associated with them, abundant Dicynodonts.

In England and Scotland, Hyperodapedon is found with Labyrinthodonts and Thecodont Reptilia of such distinctly Crocodiliform type as Stagonolepis, but no Dicynodon has been found.

In Wurtemberg, Labyrinthodonts and Thecodont Reptilia, some of them, like Belodon, eminently Crocodilian, are associated together, probably with Dinosauria; but neither Hyperodapedon nor Dicynodon have yet been discovered.

All these four faunae are connected by reptilian genera, which are respectively common to two of them : thus the British and the Indian by Hyperodapedon ; the Indian and the African, by Dicynodon ; the British and the German by Labyrinthodon (which according to Von Meyer occurs in Germany). The Labyrinthodonts and Crocodiliform reptiles are common to all four.

As the age of the beds in question is determined stratigraphically in Britain and in Germany to be Triassic, it may seem over-refinement to hesitate in declaring the African and Indian formations to belong to the same period ; but I confess that the arguments I have mentioned lead me greatly to prefer some more general term, which should indicate a wider chronological range for the duration of the terrestrial fauna in question. The term Poikilitic, originally used

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