Gilmore 1931 Microrus (3) In evidence. Everyone in a while, as one walks over the tundra, a circular built-up mound of grass is encountered. These grassmounds may be the winter rests of the microrus, who build them under the snow. The height of the mounds is 6-8" and the diameter 5-6" while a nest-like depression is evident on the top. Now are inhabited now. The mice live in all kinds of associations visited except the centers of huge rocky areas near the cliffs. Their run- ways course thru grass, tundra, along the sand & gravel of the beach, among the rocks at the edges of cliffs etc. & thru shallow seepage water. In these latter places where the water is standing on the surface of the ground, every high tussock down 1s a foot or so in diameter is riddled with tunnels. These "high" areas are probably the present homes in this marshy gro type of ground. So numerous are these mice that a dozen or so may be