eae Dwicut, Moult of Quatls and Grouse. ISI 
postjuvenal and postnuptial moults, such feathers appearing upen 
the sternal bands at a later period, namely, at the supplementary 
postjuvenal and supplementary postnuptial moults. There is no 
theory about any of these matters, —the facts are patent only 
they have not been understood. Nor is it an easy matter to under- 
stand them without following them in detail, but this is just what I 
propose to do, and I am glad to say the series I have examined 
forms a complete chain of plumages in which even the intermedi- 
ate links of moult are not missing. It is only by tracing the 
development of the successive ‘ generations’ of feathers peculiar 
to each feather tract and studying their relation to each other, 
that we may arrive at the true explanation of the apparently hope- 
less confusion of variously colored feathers found upon the Ptar- 
migans during the summer months. Instead of confusion we find 
each tract and each feather governed by the usual laws of feather 
growth, and the only confusion discoverable is that existing in 
the minds of those who have not grasped the facts. What these 
facts are I have already endeavored to sum up, but they will 
become still clearer if the reader will follow me through the pages 
which follow. As with the other Grouse and Quail the sequence 
of plumages and moults is illustrated by specimens studied in the 
natural order in which the plumages have developed. We will 
begin with Lagopus lagopus. 
Natal Down.— Downy chicks are mottled above with rusty 
brown and dull black, the crown is chestnut and a dark line runs 
behind the eye; below they are a pale buff yellow. This down, 
shown in Plate V, from a photomicrograph by Dr. Edward 
Leaming, varies little upon different parts of the body or in 
different species of the Tetraonide. Fig. 1 represents it 
attached to the apex of a juvenal feather of Lagopus lagopus 
and Fig. 2 shows it similarly attached to a juvenal feather of 
Colinus virginianus, the former plucked from the humeral tract, the 
latter from the chin where the down is shorter. It is found not 
only at the apices of the body feathers but at those of the flight- 
feathers and of the rectrices, being practically continuous with 
the barbs of the succeeding feathers, the tips often breaking away 
with the confining band which gathers them into a bundle. 
A downy chick (Amer. Mus. No. 26178, Labrador, July 1, 
