Many problems faced non-arboreal man as he descended from the trees to claim his suzerainty and place of toil. Not least among them was the question of methods of protection against the terrible creatures among which he was to live. Their production must needs be slow, and for him to meet by “direct action” with weapons invented _ad hoc_ the fierce large carnivora and clumsy but dangerous dinosaurs would have proved highly dangerous. Too long had they been in possession of his Canaan, and he could not cross his Jordan, walk seven times round their Jericho, blowing with trumpets of rams’ horns, and on the seventh day march in and “consolidate his position.” He had first to do what his descendants have always been bound to do; he had to learn to walk terrestrially long before he could think and live imperially. Sufficient for him was the evil of his day, and, as an old arboreal denizen he had much to learn and not a little to unlearn; and we know from the prehistoric pictures of his own doings and trophies, that he did in course of ages learn to walk, run and jump with variety of step and efficiency unknown in any other Primate group. We can ask, and we can but supply speculative answers as to the details of _how_ he did it, but somewhere and at some time he learned first to become as good a walking animal as later he became a talking one, and some at any rate of the steps of the process are plain for all to read to-day. How the Arch was Built. Did I not know something of the severity of the judges in such a Court of Appeal as we are facing in this case and of the opposing counsel--of the jury I have less fear--I should be disposed to settle on a half-sheet of note-paper the problem that non-arboreal man settled ages ago for himself on the ground, by a familiar saying. It really meets the non-scientific mind which is not weighed down by what Captain Marryat used to call “top-hamper,” to answer _Solvitur Ambulando_. But I hear judges and counsel both saying “This will never do,” and must address myself to opening up the case.