It is true that the bones of the Triassic Reptiles are scattered and disconnected; no complete skeleton has yet been discovered, nor has any foot been found; so that no direct comparison can be made with the steps. It is, however, my belief, from all we know of the character of the Animal Kingdom in those days, that these animals were reptilian, but combined, like so many of the early types, characters of their own class with those of higher animals yet to come. It seems to me probable, that, in those tracks where one toe is turned backward, the impression is made not by a toe, but by a heel, or by a long sole projecting backward; for it is not pointed, like those of the front toes, but is blunt. It is true that there is a division of joints in the toes, which seems in favor of the idea that they were those of Birds; for when the three toes are turned forward, there are two joints on the inner one, three on the middle, and four on the outer one, as in Birds. But this feature is not peculiar to Birds; it is found in Turtles also. The correspondence of these footprints with each other leaves no doubt that they were all by one kind of animal; for both the bipedal and the quadrupedal tracks have the same character. The only quadrupedal animals now known to us which walk on two legs are the Kangaroos. They raise themselves on their hind legs, using the front ones to bring their food to their mouth. They leap with the hind legs, sometimes bringing down their front feet to steady themselves after the spring, and making use also of their tails, to balance the body after leaping. In these tracks we find traces of a tail between the feet. I do not bring this forward as any evidence that these animals were allied to Kangaroos, since I believe that nothing is more injurious in science than assumptions which do not rest on a broad basis of facts; but I wish only to show that these tracks recall other animals besides Birds, with which they have been universally associated. And seeing, as we do, that so many of the early types prophesy future forms, it seems not improbable that they may have belonged to animals which combined with reptilian characters some birdlike features, and also some features of the earliest and lowest group of Mammalia, the Marsupials. To sum up my opinion respecting these footmarks, I believe that they were made by animals of a prophetic type, belonging to the class of Reptiles, and exhibiting many synthetic characters.