The phenomenon in question consisted of nicks in the coastline, of triangular shape and filled with shading. They occurred at intervals along it and were of the general form of carets, such marks as one makes in checking items down a list. Their position was always where a canal debouched from the diaphragm upon its career across the open continent. The canal itself was by no means necessarily visible. On the contrary, at first it was usually absent. Such was the case with those marking the departure-points of the Phison and Euphrates and of the Amenthes and Lethes, which appeared, without being well defined, from the moment the planet came to be scanned. One by one these carets stood out to view, punctuating the points where canals later were to show or terminating those that already existed. Strung thus with them at intervals was the whole coastline of the diaphragm, beginning with the Mare Icarium and stretching round through the Mare Tyrrhenum, Mare Cimmerium, Mare Sirenum, and Mare Erythraeum to the Mare Icarium again. As the planet got nearer to the earth their peculiar shape began to define itself, and it was again in the case of those giving origin to the Phison and Euphrates that the recognition came first. What had appeared earlier simply as a spot now stood out as two triangular notches, indenting the coast and giving exit at their apices, the eastern one to the Phison, the western to the Euphrates. These were the things, then, that had constituted the Portus Sigaeus of Schiaparelli. Commonly the carets lie at the bottom of well-marked bays, as, for example, those terminating the Syrtis Minor and the Sinus Titanum. But frequently they are placed in the very midst of a long and otherwise unaccented coast, as is the case in mid-course of the Mare Cimmerium and the Mare Sirenum. Yet in no instance is the thing unassociated with a canal. In every case one or more canals leave the caret for their long traverse down the disk.