In passing up this valley, an almost never-failing object of interest was furnished by the univalve shells found along its banks, and by the variety in size, shape, and color which they exhibited. Of these, the late Mr. Barnes has described, from my duplicates, the U. plicatus, U. verrucosus, U. ventricosus, U. planus, U. obliqua, and U. gracilis.[120] We frequently observed the scolipax minor, the plover, the A. alcyon, a small yellow bird, and C. vociferus, along its sandy shores; and, in other positions, the brant, the grouse, the A. sponsa, and the summer duck, and F. melodia. A range of hills extends from the Mississippi, on each shore, to within twenty miles of the Portage, where it ceases, on the south side, but continues on the north--receding, however, a considerable distance. This section is called the Highlands of the Wisconsin. The stratification is exclusively sandstone and limestone, in the usual order of the metalliferous series of the West, and lying in horizontal positions. [120] American Journal of Science, vol. vi. p. 120, &c. There are two kinds of rattlesnake in the Valley of the Wisconsin. The larger, or barred crotalis, is confined to the hills, and attains a large size. I killed one of this species at the mouth of a small cave on the summit of a cliff to which I ascended, which measured four feet in length, and had nine rattles. Its great thickness attracted notice. Attaching a twig to its neck, I drew it down into the valley as a present to our Indians, knowing that they regard the reptile in a peculiar manner. They found it a female, having eleven young, who had taken shelter in their maternal abdominal-covering. The Ottowas carefully took off the skin, and brought it with them. The second kind of this reptile is called prairie rattlesnake, is confined to the plains, and does not exceed fifteen or twenty inches in length. The Indians had reported localities of lead, copper, and silver at various places, but always failed, as we ascended, to reveal anything of more value than detached pieces of sulphuret of iron, or brown iron-stone. When we reached the portage, a Winnebago, who had been the chief person in making these reports, came with great ceremony to present a specimen of his reported silver. On taking off the envelop it turned out to be a small mass of light-colored glistening folia of mica. We had found the horizontal rocks along the stream thus far, but the primitive shows itself, within a mile north of the portage, in orbicular masses in situ, coming through the prairies.