“In the heat of summer these huge animals ... often graze on the low grounds of the prairies, where there is a little stagnant water lying amongst the grass, and the ground underneath, being saturated with it, is soft, into which the enormous bull, lowered down upon one knee, will plunge his horns and at last his head ... soon making an excavation in the ground, into which the water filters from among the grass, forming for him in a few moments, a cool and comfortable bath.... By this operation, which is done perhaps in the space of half an hour, a circular excavation of fifteen or twenty feet in diameter, and two feet in depth is completed, and left for the water to run into, which soon fills it to the level of the ground.... To these sinks, the waters lying on the surface of the prairies are continually draining and lodging in them their vegetable deposits, which, after a lapse of years, fill them up to the surface with a rich soil, which throws up an unusual growth of grass and herbage, forming conspicuous circles which arrest the eye of the traveler.” Mr. C. farther adds that “these strange circles often occur in groups, and of different sizes.”—_Catlin’s N. A. Indians_, Vol. I. p. 249. NOTE JJ. ÆCIDIUM, page 255. Æcidium is a genus of minute parasitic plants, belonging to the order of Fungi. They are found upon the leaves, the bark, and even upon the flowers of living plants, but are altogether distinct from the cuticle of the vegetable on which they have their growth. They are always tubular in their form. On the weeds and trees of northern countries they are very common, and a great many species have attracted the attention of botanists, while to the careless eye, they often appear like the nests of some small insect. The common fancy among farmers that the barberry-bush is injurious to wheat, producing rust in the grain, is owing to an æcidium growing on the barberry, which covers its leaves with a bright, orange powder. The only resemblance, however, between the rust of wheat and the barberry blight lies in the color. The rust in wheat, is in fact another, and a wholly different species of this same genus æcidium; it is called by botanists, _Puccinia graminis_. Another common æcidium is that of the pear-tree, which has received the name of _Peridia_. NOTE KK. POLLARDING TREES, page 267.