Mr. Harlow (1914) found that in one instance the drilling of the nesting cavity was in progress in March and was continued “all during March and April.” The female worked alone, and the male continued near by. This nest, an unusually early one, contained, on April 30, three eggs. In the Northern States the eggs commonly are laid early in May. Incubation continues, according to Burns (1915), for 18 days. The young leave the nest about the middle of June. The range of date in nesting is illustrated by two records that come from Centre County, Pa. (Scoville, 1920; Burleigh, 1931). One is of a set of eggs that hatched on May 11. These eggs must have been laid before April 23. The other record is of a set collected May 11 and found to be practically fresh. The interval at which these two cases stand apart is about 25 days. Scoville (1920) quotes Harlow, a collector whose experience was chiefly in Centre County, to the effect that “May 10 is the standard date for a full clutch of eggs.” Records of nests are at hand from Maine, New Hampshire, New York, Pennsylvania, Ohio, and Wisconsin. The total body of data, however, is small; and it is not possible to discover what the difference may be in mean nesting date from south to north within the region covered. There is a record from Maine, for instance (Morrell, 1901), of a set of eggs found to be heavily incubated as early as May 13. _Eggs._--The eggs are white, with a gleaming smoothness and translucence of shell. They rest at the bottom of the cavity, on the bare bed of finely splintered wood. Three eggs often complete the set, but more commonly four. Of 17 recorded sets, 4 are sets of three, and 13 are sets of four. Some of the earlier writers (Wilson, for instance, 1811) said the number of eggs might be five or even six; but no specific record of so large a number has been found. The eggs are of ovate outline. The measurements of 51 eggs average 33.16 by 25.21 millimeters; the eggs showing the four extremes measure =38.2= by =27.1=, =30.2= by 25.2, and 33.05 by =23.75= millimeters. There are cases on record in which a pair of these birds, robbed of their eggs, have laid again (and in the same cavity); with this qualification, there is but a single brood in a season.