Polar seas (see Blue band);
fresh water, [162].
Poles, Martian, determination of, [36].
Pons Hectoris, [78].
Portus Sigaeus, nicks in the coastline, [207], [266], [267];
embouchure to Phison and Euphrates, [218].
Precipitation, [51], [79], [154], [155];
effect on glaciation, [52].
Presentation, a, defined, [287], [288].
Probability, law of, [160].