These most singular plants are interesting on several accounts, particularly the regular expansion of their large and beautiful flowers towards the evening of several successive days. In the morning the long and slender petals, and the petal-like nectaries, which compose the flower, are found accurately closed upon each other, forming a cone of about an inch in length. In this situation they remain, if the weather be clear, until about sunset, when they gradually expand. If the weather be dark and cloudy, with a humid atmosphere, they are awakened from their slumbers at an earlier hour. We have, in some instances, seen them fully expanded early in the afternoon; but this has always been in stormy or cloudy weather. In this particular the Bartonia bears some resemblance to the great night-flowering cereus, to which it is closely allied; but the gaudy petals of the cereus, once unfolded, fall into a state of irretrievable collapse, whereas, the Bartonia closes and expands its flowers for many days in succession.[132] [132] Other plants were collected about this encampment, among which we distinguished an interesting species of ranunculus, having a flower somewhat larger than that of R. fluviatilis with which it grows, often extending, however, to some distance about the margins of the pools in which it is principally found. R. _amphibius_; slender, floating or decumbent, leaves reniform, four or five lobed, divisions cuneate, oblong, margin crenate, petioles long and alternate. The submersed leaves are, in every respect, similar to the floating ones. Pentstemon _erianthera_, N., Poa _quinquefida_, Potentilla _anserina_, Scrophularia _lanceolata_, Myosotis _glomerata_, N.? &c. were also seen here.—JAMES. A number of young magpies were seen in the bushes about the river; also the nests and young of the mockingbird, (turdus orpheus, Vieil.) The prairie-dog villages we had observed to become more frequent and more extensive as we approached the mountains; and we had now constant opportunities of contrasting the stupendous elevations of the Andes with the humble mounds cast up by this interesting little animal. We observed in the {183} numerous burrows an appearance of greater antiquity than in those more remote from the mountains. Many of the mounds occupy an extent of several yards in diameter, though of but inconsiderable elevation, and with the exception of the present entrance, overgrown with a scanty herbage, which always marks the area of the prairie-dog villages. Indeed we have observed several large villages, with scarce a trace of vegetation about them. The food of the marmot consisting of grasses and herbaceous plants, it is not perhaps easy to assign a reason for the preference which, in selecting the site of his habitation, he always shows for the most barren places, unless it be that he may enjoy an unobstructed view of the surrounding country, in order to be seasonably warned of the approach of wolves, or other enemies.