I obtained from the Sioux some very carefully moulded pyramidal-shaped pieces of the blue and green clays from the valley of the St. Peter's, which they employ in painting their pipe-stems and persons. The coloring matter of these appears to be carbonate of copper. It is brought from the Blue Earth River. I also obtained from the Indians very small and carefully tied leathern bags of the red oxide of iron, which they obtain in the state of a dry, powdery mass, on the prairies near the Big Stone. The Indians brought me, from the same region, crystals of salt, scraped up from the margin of certain waters on the prairies, of a dark cast, mixed with impurities. The tendency of these crystals to assume a cubic form was quite distinct. The most interesting development, in the mineralogical way, consisted of small lumps of native copper, which I obtained on an eminence on the banks of the Mississippi, directly opposite the influx of the St. Peter's. They occupy, geologically, a diluvial position, being at the bottom of the prairie-drift stratum, and immediately above the superior limestone. In the luxurious kitchen gardens of Camp Leavenworth, great depredations have been made by a small quadruped of a burrowing character, called gopher. By patient watching, gun in hand, one of these was killed, and its skin preserved and prepared. The animal is ten inches long to the termination of the tail, with a body very much the size and color of a large wharf-rat. It has five prominent claws, and two broad cutting teeth, but its most striking peculiarity is a duplicature of the cheek, which permits it to carry earth to the mouth of its burrow. It has been called the pouched rat. Sir Francis Drake found a similar animal in his visit to the Gulf of California, in 1587. The distribution of this species, of which this seems to be the northern limit, is very wide through Atlantic America, and it is known to be destructive to vegetation throughout Alabama, Georgia, and the Carolinas. I had, two years ago, been led to notice its ravages in Missouri and Arkansas. But the animal called gopher, in the southern country, is a burrowing tortoise, and the name is improperly applied to this species, which is the _Pseudostoma pinetorum_. A peculiar species of squirrel was observed in this vicinity, which is also found to be a destructive visitor to the military gardens. In appearance, this species resembles the common striped squirrel, but it has a more elongated body, and shorter legs. The body has six black stripes, with the same number of intervening lines of spots, on a reddish-brown skin. This Minnesota squirrel has, since the return of the Expedition, been named, by the late Dr. Samuel L. Mitchell, _sciurus tredeceum_.