The color of the natal downs of both species is similar. Dwight (1900:190), who saw newly hatched nestlings only of the Sharp-tailed Sparrow, described the color as grayish wood-brown. A series of white neossoptiles is present at the posterior end of the ventral tract in both species. These feathers are more numerous in the Seaside Sparrow. Dwight (1900:98) saw no neossoptiles on the underparts of any of the passerines he examined. Seaside Sparrows have a mid-dorsal row of downs in the dorsal tract near the uropygium. These feathers are lacking in the Sharp-tailed Sparrow and constitute the major difference, in this plumage, between the two species. The neossoptiles of three Seaside Sparrows and one Sharp-tailed Sparrow were counted. These counts were checked on the young birds studied in the field. The number and placement of these feathers appear in plate five. There appears to be a consistently greater number of natal downs in Seaside Sparrows, when compared with Sharp-tailed Sparrows. TABLE 1--DAILY WEIGHT IN GRAMS OF NESTLING SEASIDE SPARROWS AND SHARP-TAILED SPARROWS FROM LAVALLETTE, OCEAN CO., NEW JERSEY. ======+================================================================+ Day | _Ammospiza maritima_ | Average | ------+---------+------+---------+------+------+------+------+---------+ 0 | ... | 2.2 | 2.3 | ... | ... | 2.2 | 1.8 | 2.1 | 1 | 3.0 | 3.3 | 3.5 | 3.7 | 3.3 | 2.6 | 2.1 | 3.1 | 2 | 4.6 | 5.0 | 5.2 | 5.0 | 4.8 | 3.7 | 3.0 | 4.5 | 3 | 7.0 | 5.5 | 7.2 | 6.9 | 6.9 | 5.9 | 4.7 | 6.3 | 4 | 9.4 | 8.1 | 10.6 | 9.1 | 9.1 | 7.6 | 6.4 | 8.6 | 5 | 12.5 | 11.1 | 12.3 | 11.4 | 11.1 | 9.9 | 8.7 | 11.0 | 6 | 14.6 | 13.1 | [1]11.1 | 13.9 | 13.7 | 12.6 | 9.6 | 13.0 | 7 | [1]11.6 | 13.9 | 12.1 | 15.1 | 14.8 | 14.3 | 11.8 | 13.7 | 8 | 14.9 | 15.5 | 13.4 | 14.9 | 14.8 | 14.6 | 12.4 | 14.4 | 9 | 15.2 | 15.8 | 13.8 | 16.2 | 16.1 | 16.0 | 14.4 | 15.4 | 10 | ... | ... | ... | ... | 15.9 | 15.5 | 14.3 | 15.2 | ------+---------+------+---------+------+------+------+------+---------+