In discussing the Median calendar, the importance which seems to have been given by the ancestors of the Medes to the constellation Sagittarius, at a date when it marked the spring equinox, was dwelt upon. It will, I think, appear likely, when we come to study Plates XIX. and XX., that as early as 4600 B.C. constellations were imagined to honour and mark the equinoctial as well as the solstitial seasons. Perhaps then, at that date the constellation Sagittarius was extended to its present dimensions; and it may be that some centuries later, when the colure of the _winter solstice_ had passed into the constellation Aquarius, some astronomers desired--like Gudea of Lagash and Tchuen-Hio in China--to honour that season, and to make it the beginning of the year. It may be that such astronomers dealt with the eleventh constellation of the Zodiac, as earlier ones had dealt with Sagittarius, and that they added to what was possibly originally only a _water jar_, Amphora, the figure of the _water pourer_ Aquarius. These ideas are put forward very speculatively. They were partly suggested by noticing that in the Indian Zodiac the name of the constellation Sagittarius is merely Dhanus (arrow), and the name of Aquarius is Kumbha (water jar). In the diagrams which we have been discussing, it will be observed that only the twelve figures of the Zodiac, and _two_ of the extra-Zodiacal constellations, are given in continuous outline, one of these two is Draco--the dragon or serpent whose folds surround the _Pole of the Ecliptic_--the central point of the circle of the Zodiac. That the astronomers who traced out the circle of the Zodiac on the heavens, and imagined its twelve strange figures, should also have devoted attention to, and marked out, its central point, is not improbable. The _Pole of the Ecliptic_, unlike the _Pole of the Heavens_, is immoveable amongst the fixed stars. At 6000 B.C., as at the present date, the stars of Draco surrounded this point--a point not itself marked by any conspicuous star. We have not, however, I think, at present sufficient grounds for deciding at what exact date the constellation Draco was imagined under the form it now holds. But that it is very ancient there is no doubt. For the first depicting on the vault of heaven of the figure of Bootes, I claim with much stronger conviction the date of 6000 B.C., and the latitude of 45° north. For then and there Bootes might be seen at midnight of the summer solstice, standing upright on the northern horizon, his head reaching nearly to the Pole of the Heavens. Never since that date has he held so commanding a position in the sky, nor at any more southern latitude could his whole figure have been represented as standing on the horizon.