are essential points
of difference in the habits of the two species. The guanacos are
dwellers among the rocks, and are most at home when bounding from cliff
to cliff, and ledge to ledge. They make but a poor run upon the level
grassy plain, and their singular contorted hoofs seem to be adapted for
their favourite haunts. The vicunas, on the contrary, prefer the smooth
turf of the table plains, over which they dart with the swiftness of the
deer. Both are of the same family of quadrupeds, but with this very
essential difference--the one is a dweller of the level plain, the other
of the rocky declivity; and nature has adapted each to its respective
_habitat_."

Here the narrator was interrupted by the hunter-naturalist, who stated
that he had observed this curious fact in relation to other animals of a
very different genus, and belonging to the _fauna_ of North America.
"The animals I speak of," said he, "are indigenous to the region of the
Rocky Mountains, and well-known to our trapper friends here. They are
the big horn (_Ovis montana_) and the prong-horned antelope (_A.
furcifer_). The big horn is usually denominated a sheep, though it
possesses far more of the characteristics of the deer and antelope
families. Like the chamois, it is a dweller among the rocky cliffs and
declivities, and only there does it feel at home, and in the full
enjoyment of its faculties for security. Place it upon a level plain,
and you deprive it of confidence, and render its capture comparatively
easy. At the base of these very cliffs on which the _Ovis montana_
disports itself, roams the prong-horn, not very dissimilar either in
form, colour, or habits; and yet this creature, trusting to its heels
for safety, feels at home and secure only on the wide open plain where
it can see the horizon around it! Such is the difference in the mode of
life of two species of animals almost cogenerie, and I am not surprised
to hear you state that a somewhat like difference exists between the
guanaco and vicuna."

The hunter-naturalist was again silent, and the narrator continued.

"A few more strides up the mountain pass brought us to the edge of the
plain, where we expected to see the vicunas. We were not disappointed.
A herd was feeding upon it, though at a good distance off. A beautiful
sight they were, quite equalling in grace and stateliness the lordly
deer. In fact, they might have passed for the latter to an unpractised
eye, particu