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158 THE CONDOR Vol. XX In two of the sets the eggs were aH individually embedded in the baked earth to a depth of one-eighth to one-fourth of an inch, evidently having set- tled when the surface of the ground was reduced to soft mud by rain-water col- lecting in the slight depressions. As the ground dried the eggs were fixed in a perfect mould or matrix, from which they could not roll. In fact they could hardly be disturbed at all by the sitting birds. The only nesting material was a small quantity of fine, dry rootlets and dead "crowns" of gramma grass, the eggs in some instances being slightly embedded in this lining. As it is also present in aH other depressions on the prairie it is highly probable that here as elsewhere it was deposited about the eggs by the wind and not through the agency of the birds themselves. (See figure 25.) The protective coloration of Fig. 25. EGGS AND NEST OF MOUNTAIN PLOVER, AS PHOTOGRAPHED MAY Z0, 1917, AROt,T TWF, NTY MILEIS EAIST OF DENVER, COLORADO. EACH EGG HAD ?SETTLED IN THE SOFT MUI} VIIICtI VHEN DRIED FORMED A PERFECT ?fOULD OR CA?T FROM WHICH IT COULD NOT ROLL. the nest and eggs, as well as of the rear view of the birds themselves, even when in motion, is unsurpassed. In no instance, except one hereinafter noted, was tire bird seen to leave the nest, nor was any nest found except in the im- mediate vicinity of moving birds. The site of the first pair of birds located and worked on May 13, 1917, was visited and carefully searched on three subsequent trips, always revealing one or both birds in practically the same spot, but never the nest. On May 20, during a rain storm, we noticed two birds running at a dist- ance of about thirty yards ?rom the road. Stopping, four of us spent more than