killed, and these four were dragged from the field by their companions."

Just above the site of the city of Yankton, and near what is still known
as Bon Homme Island, Captain Clark explored a singular earth formation
in a bend of the river. This had all the appearance of an ancient
fortification, stretching across the bend and furnished with redoubts
and other features of a great fort. In the journal is given a glowing
account of the work and an elaborate map of the same. Modern research,
however, has proved that this strange arrangement of walls and parapets
is only a series of sand ridges formed by the currents of the river and
driftings of sand. Many of these so-called earthworks are situated on
the west bank of the Upper Missouri, in North Dakota and South Dakota.

A few days later, the party saw a species of animal which they described
as "goats,"--very fleet, with short pronged horns inclining backward,
and with grayish hair, marked with white on the rump. This creature,
however, was the American antelope, then unknown to science, and first
described by Lewis and Clark. While visiting a strange dome-shaped
mountain, "resembling a cupola," and now known as "the Tower," the
explorers found the abode of another animal, heretofore unknown to them.
"About four acres of ground," says the journal, "was covered with small
holes." The account continues: "These are the residence of a little
animal, called by the French petit chien (little dog), which sit erect
near the mouth, and make a whistling noise, but, when alarmed, take
refuge in their holes. In order to bring them out we poured into one of
the holes five barrels of water without filling it, but we dislodged and
caught the owner. After digging down another of the holes for six feet,
we found, on running a pole into it, that we had not yet dug half-way to
the bottom: we discovered, however, two frogs in the hole, and near it
we killed a dark rattlesnake, which had swallowed a small prairie dog.