idea of the immense length of the canal, which is no less than three thousand four hundred and fifty miles long. Nearly in the centre of the disk is the peninsula Atlantis, the most easterly of the set of comet-tail peninsulas similar to those seen in Plate I., all connecting the so-called continent with the islands to the south. These Islands look not unlike great vertebrae of the planet’s backbone, in consequence of the canals which cut them up so symmetrically. Atlantis shows well, between Mare Sirenum and Mare Cimmerium, two areas suggestively alike in general shape and directional trend. Both are seen to be crossed by canals which connect, at what resemble nicks in the coast-line, with the canals in the bright regions.
In Plate X. the Mare Cimmerium is central. So, also, well down the disk, is the Trivium Charontis. This is a very important junction, no less than nine canals already being known to connect with it, which, taken in the order, east, north, west, and south, are the Orcus, the Erebus, the twin Tiades, the Styx, the Cambyses, the Cerberus, the Laestrygon, the Tartarus, and so back to the Orcus again. In this picture the Laestrygon traverses nearly the centre of the disk. To the right of the Trivium Charontis is the region called Elysium, one of the brightest parts of the planet. It was here that Mr. Douglass made his interest-
