104 Trans. Acad. Sci. of St. Louis 
appeared on back, wings and head, fourth day. On the fifth 
day primary quills were 1.5 mm. long; breast quills .7 mm. long. 
On the sixth day primaries were 7.5 mm. long; feathers of the 
head, back and breast began to unsheath. Down began to shed 
on the seventh day, when primaries were 1.2 cm. long and un- 
sheathing at the tip. Down was rapidly disappearing on the 
eighth day; the tail feathers protruded .15 cm. beyond the end 
of the body ; longest primaries were 1.6 cm. long and unsheathed 
cont iseters 
u 
Figure 14 
“ / ; 7 Sl ee era 
pk 2 8 ‘ 8 ‘ ? @ ° ” 
Fig. 14. Growth in length of a May set of Prairie Horned Lark nest- 
lings (nest C,, May 6 to 15, inclusive, Ithaca, N. Y., 1927). 
-30 cm. On the ninth day a few bits of down still remained; the 
longest primary was 2.4 em. and unsheathed .8 em.; tail was - 
em. On the tenth day the longest primary was 2.88 em., ope? 
‘9 cm.; the tail was 1.12 em. long. The plumage was n0W 
essentially that of the matured juvenile: down practically off, 
plumage of upper surface black, each feather with a curious 
triangle of brown at its tip. The lower surface was white except 
the throat. A fifteen-day-old Lark, captured by strenuous run- 
