These were not, however, the earliest known instances of Carboniferous reptiles. In 1841, Sir William Logan found footprints of a reptile at Horton Bluff, in Nova Scotia, in rocks of Lower Carboniferous age. In 1844, Von Dechen found reptilian bones in the coal-field of Saarbruck; and in the same year Dr. King found reptilian footprints in the Carboniferous of Pennsylvania. Like Robinson Crusoe on his desert island, we saw the footprints before we knew the animals that produced them; and the fact that there were marks on a slab of shale or sandstone that must have been made by an animal walking on feet, was as clear and startling a revelation of the advent of a new and higher form of life, as were the footprints of Man Friday. Within the thirty years since the discovery of the first slab of footprints, the knowledge of coal formation reptiles has grown apace. I can scarcely at present sum up exactly the number of species, but may estimate it at thirty-five at least. I must, however, here crave pardon of some of my friends for the use of the word reptile. In my younger days frogs and toads and newts used to be reptiles; now we are told that they are more like fishes, and ought to be called Batrachians or Amphibians, whereas reptiles are a higher type, more akin to birds then to these lower and more grovelling creatures. The truth is, that the old class Reptilia bridges over the space between the fishes and the birds, and it is in some degree a matter of taste whether we make a strong line at the two ends of it alone, or add another line in the middle. I object to the latter course, however, in the period of the world's history of which I am now writing, since I am sure that there were animals in those days which were batrachians in some points and true reptiles in others; while there are some of them in regard to which it is quite uncertain whether they are nearer to the one group or the other. Although, therefore, naturalists, with the added light and penetration which they obtain by striding on to the Mesozoic and Modern periods, may despise my old-fashioned grovellers among the mire of the coal-swamps, I shall, for convenience, persist in calling them reptiles in a general way, and shall bring out whatever claims I can to justify this title for some of them at least. Perhaps the most fish-like of the whole are the curious creatures from the coal measures of Saarbruck, first found by Yon Dechen, and which constitute the genus _Archegosaurus_. Their large heads, short necks, supports for permanent gills, feeble limbs, and long tails for swimming, show that they were aquatic creatures presenting many points of resemblance to the ganoid fishes with which they must have associated; still they were higher then these in possessing lungs and true feet, though perhaps better adapted for swimming then even for creeping.