repay close study. The dance could hardly be a
mating performance since Mac saw it in late May and by that time the
young had already been born.

One morning at the "Marmot Camp," as we named the one where we first
began real collecting, Yvette saw six or seven young animals on top
of a mound in the green grass. We went there later with a gun and
found the little fellows playing like kittens, chasing each other
about and rolling over and over. It was hard to make myself bring
tragedy into their lives, but we needed them for specimens. A group
showing an entire marmot family would be interesting for the Museum;
especially so in view of their reported connection with the
pneumonic plague. We collected a dozen others before the summer was
over to show the complete transition from the first yellow coat to
the gray-brown of winter.

Like most rodents, the marmots grow rapidly and have so many young
in every litter that they will not soon be exterminated in Mongolia
unless the native hunters obtain American steel traps. Even then it
would take some years to make a really alarming impression upon the
millions which spread over all the plains of northern Mongolia and
Manchuria.

Since these marmots are a distinctly northern animal they are a
great help in determining the life zones of this part of Asia. We
found that their southern limit is at Turin, one hundred and
seventy-five miles from Urga. A few scattered families live there,
but the real marmot country begins about twenty-five miles farther
north.

The first hunting camp was eighty miles south of Urga, after we had
passed a succession of low hills and reached what, in prehistoric
times, was probably a great lake basin. When our tents were pitched
beside the well they seemed pitifully small in the vastness of the
plain. The land rolled in placid waves to the far horizon on every
hand. It was like a calm sea which is disturbed only by the lazy
progress of the ocean swell. Two _yurts_, like the sails of
hull-down ships, showed black against the sky-rim where it met the
earth. The plain itself seemed at first as flat as a table, for the
swells merged indistinguishably into a level whole. It was only when
approaching horsemen dipped for a little out of sight and the
depressions swallowed them up that we realized the unevenness of the
land.

Camp was hardly made before our Mongol neighbors began to pay their
formal calls. A picturesque fellow, blazing with color, woul