Note 40 — Chapter VII · Prairies in Minnesota and Iowa.—Boulders.—Glacial Drift.—Wild Rice.—Snow Storm.—Nebraska.—The Pawnees.—Human Sacrifices.—Note on Indian Customs in War and Cannibalism.—Prairie Fires.—Prairie-Dog Villages.—Rattlesnakes.—Variations in the succession of growths of Trees.—Causes of absence of Trees upon Prairies.—Shoshone Indians on the Western Deserts.—Note upon Ute Indians and Fuegians.

When I was at the village of San Domingo del Palenque in Central America, Dr. Coller, a resident there, told me he had carried out, during several years, a series of investigations to ascertain the reasons for the existence of large green savannahs in the heart of the adjacent forests. He had formed the conclusion that those open spaces were caused by the exceptional character of the ground which, he said, differed from that upon which the trees grew. The similar openings amongst the forests in Ceylon called patenas, are, I believe, also supposed to be the effect of the nature or poverty of the land.

It is noticeable that the forests usually skirt or surround savannahs in sharp well-defined outlines like an enclosing barrier, in the same manner as the meadows, formed by the consequences of the action of beavers, occur in Michigan.