swaths that make with the Jamuna a nearly right-angled triangle. The lower one parallel to the edge of the disk is the Dardanus; the other, ending at the south with the Jamuna in the Aurorae Sinus, is the Ganges, one of the largest and most important Martian canals. At the date of the drawing, it was distinctly double. The doubling is very curiously prolonged by a narrow rectangle lying in the midst of the dark regions of the south. Some idea of the size of these strangely geometrical markings may be got by remembering that a degree on Mars represents thirty-seven miles. Skirting the edge of the dark regions westward, we come to a short canal, the Hebe, leading to Fons Juventae, one of the tiniest markings perceptible on the disk, from which, however, some six canals have been found to radiate. Schiaparelli detected it in 1877, searched for it in vain in 1879, but at subsequent oppositions found it again, happier than Ponce de Leon in his futile quest after an earthly Fountain of Youth. Proceeding still farther west, we reach the entrance of the Agathodaemon, at the point where the edge of the dark regions abruptly trends southward. This canal brings us to the Solis Lacus region, one of the most interesting parts of the planet.
In Plate V. it has swung round into better view, where we will therefore consider it.