The country has been judiciously divided into three zones, which are, proceeding from north to south, the Tundra (or Arctic Moss) Zone, the Great Forest Zone, and lastly the Agricultural Zone; the south and south-west of the last-named includes the steppes, as well as the Altai and Sayan Mountains. It would be impossible to trace a line of exact demarcation between these different zones, for the transition is extremely gradual; but, speaking generally, the land situated north of 63° and 64° latitude is barren of all vegetation excepting mosses and lichens. The subsoil is eternally frozen, but the surface thaws in summer very slightly, thereby turning the country into one vast marsh. The rivers remain frozen during nine months of the year. Under these circumstances, cultivation is out of the question. To the south-western limit of this zone, at Beriozof on the Obi, the medium temperature all the year round is 5° C. below zero, and in winter it goes down to 23°. The average in summer is 13·5°, and that of the hottest month 18°, which is about the same as the heat in Paris in July; but the warm weather lasts so short a time as to be useless for agricultural purposes. To the east the climate becomes rapidly severe, and at Verkhoyansk, a village situated in the Yakutsk district, latitude 67°, one of the coldest regions in our hemisphere is reached. The average throughout the year is 17° C. below zero; during the three winter months it is 47°, and in January 49°. The minimum is about 68° below zero. What characterizes this dreadful region is that to the extreme cold in winter succeeds a very short but relatively warm summer. The medium thermometrical reading during the warm season is 13°, which rises to 15° for the month of July, during which the mercury sometimes rises to 25° in the shade. The difference between the temperature of the warmest and the coldest months of the year is about 64°, that is to say, four times what it is in Paris. It is very remarkable that in whatever direction you go from Verkhoyansk, even northward, the climate becomes less rigorous, thanks to the comparative mildness of the winter. As to the summer, it scarcely merits the name, falling to 9° and even to 3° C. on the borders of the Arctic Ocean.