At the next presentation, May 26 to June 8, the phenomena were repeated, and with increasing clarity. And then of a sudden, on May 29, I saw the long-given-up Lucus Moeris. There it was indubitably. And its definiteness was the most astonishing part of the affair. It was no question of difficult detection. Indeed, I had not been on the lookout for it, having searched the region too often fruitlessly before to have left incentive to search again. And so, when I was not searching, the thing of its own accord stepped forth to sight. It was a small round dot, like to any other oasis, and showed, as it were, a black pearl pendent by the Nepenthes from the Syrtis’s ear. For the Libyan bay made a dark projection of the sort high up on the Syrtis’s eastern side, from which the Nepenthes, precisely as Schiaparelli had drawn it, curved down to the point where the Thoth and Triton met. All three canals were geminated, the gemination being about three degrees wide. [Illustration: Advent of the Lucus Moeris. May 29.] And now occurred the last act in the drama. In July the Amenthes reappeared, showing alongside of the Thoth-Nepenthes, and thus removing any possible doubt as to their separate identity. It had, indeed, become the stronger of the two, having gained in strength in the interval between June and July and the Thoth-Nepenthes having lost. The lines were in process of relapsing into the _status quo ante_. Had these three presentations not been watched, the brief apparition of the Thoth-Nepenthes had been missed and with it the revealing of its curious character, and of certain deductions thereupon. [Illustration: Amenthes with Thoth-Nepenthes. July.] First among these is a truth of which I have long been convinced; to wit, that when a seeming discordance arises between the portrayals of a canal, it is commonly not a case of mistake nor of change, but one of separate identity. The canal has not shifted its place, nor has an error been committed; the fact is that one canal has been observed at one time, another at another. So it was here, and thus were the old and the new observations reconciled. There had been no mistake in either. Two separate canals accounted for the discrepancy, and only an unfounded distrust of the accuracy possible in such observations was to blame for any failure to recognize the fact. Now, scrutiny of the notes upon the appearance of the two canals, together with their labeling by the seasonal longitudes of the planet at the dates they were made, discloses a curious relation between the two. The seasonal longitudes are important, as they date the phenomena according to the Martian calendar. Ordered thus, the successive aspects reveal first a seasonal change in each canal and then over and above this a secular one. And this secular change was such as to cause the two canals to alternate in visibility. When the one was present the other was not, and _vice versa_. [Illustration: CARTOUCHES OR CURVES OF VISIBILITY OF