On 30th July on the left side the central Rectrix and the first and second posterior coverts were still growing, on the right side the central Rectrix was also growing, but the first and second posterior coverts had ceased growth and formed their quills.
"Hormones and Heredity"
J. T. Cunningham
On 2nd September the left central Rectrix was almost at the end of its growth, the right had ceased to grow a little before.
"Hormones and Heredity"
J. T. Cunningham