Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/242

 into the water, and that which takes to the sea habitually. All that can be said is that the Lacertilia are so predominantly terrestrial a group, that a member of the group is to be presumed terrestrial, or at any rate fluviatile, unless evidence appears to the contrary. True there is no evidence to the contrary in the case of Hyperodapedon; but, on the other hand, all that we know of its contemporaries and compatriots, Stagonolepis and Telerpeton, leads to the belief that they were terrestrial or semiaquatic. Telerpeton, I have little doubt, was altogether terrestrial. Sphenodon, the existing ally of Hyperodapedon, is a sluggish animal, which lives, in part, at any rate, on insects and small birds, and is said to frequent burrows in the sand near the sea-shore. The fact that no marine remains have ever been found in the deposits which contain Hyperodapedon- remains is negative evidence which leads in the same direction ; and it is strongly confirmed by the association of Labyrinthodonts with Hyperodapedon in Warwickshire and in India, — Labyrinthodonts, like all other amphibia, being confined to the land and fresh water.

The question of the terrestrial habit of Hyperodapedon assumes a great importance when the wide distribution of the genus is taken into consideration. It has now been discovered in the North of Scotland, in the centre of England, and in Central India ; and if it were, as I doubt not it was, a terrestrial or semiterrestrial animal, that alone indicates the existence of a very extended mass of dry land in the Northern hemisphere during the period in which it lived. And the proof of the existence of continental land in the Northern hemisphere acquires increased interest when we consider the evidence which shows what period this was.

The cardinal fact in that evidence is the occurrence of Hyperodapedon in the Coton-End Quarry in Warwickshire, as proved by Dr. Lloyd's specimen. It has never been doubted, I believe, that the Sandstone in which this quarry is excavated is of Triassic age. It has yielded Labyrinthodonts and Thecodont Saurians ; and its stratigraphical position is such that the only question which can possibly arise is, whether it is Triassic or Permian.

As next in order of value, I take the discovery of Hyperodapedon in the Devonshire Sandstone, the determination of which as Trias rests, as Mr. Whitaker will inform you, upon independent grounds.

Thirdly comes the occurrence of the closely allied Rhynchosaurus in the Trias of Shropshire — a fact of subordinate value, but still by no means to be left out of sight.

These facts leave no possible doubt, as it seems to me, that Hyperodapedon is a reptile of Triassic age ; but whether it is of exclusively Triassic age or not, and therefore whether it is, or is not, competent to serve as a mark of the Triassic age of the deposit in which it occurs, is quite another matter, and one respecting which it behoves us to speak very cautiously.

Crocodiles, with the same vertebral character as those which now live, and not known to be distinct even from the modern restricted genus Crocodilus, lived at the epoch of the Greensand, or, in other