BLACKBIRD. 215 
coloured spots; belly, sides, and under tail-coverts, hair- 
brown. 
The young have the upper parts blackish brown, darker 
in the males, each feather having a central spot or streak of 
pale rufous: under parts light rufous brown, with terminal 
dark spots, generally more distinct in the males. 
Young males having completed their first autumn moult, 
are intermediate in the general colour of their plumage be- 
tween that of the adult female and adult male, the yellow 
also beginning to appear at the poimt of the beak. 
Having stated at page 166 some of the laws which appear 
to govern the assumption and changes of colour in the 
plumage of birds, I may here add a few remarks on the 
disposition and situation of the feathers themselves. It is 
not, however, my intention to attempt to describe the 
structure and growth of a feather, one of the most com- 
plicated of all the various productions of the skin in 
animals ; such minute anatomical details would be out of 
place im a work intended to be popular, but the reader 
who is inclined to pursue this part of the subject may con- 
sult with advantage the “ Developement of Feathers,” by 
F. Cuvier, in the Mémoires du Museum, tom xiii; or the 
article “‘ Aves,” in the first volume of the Cyclopedia of 
Anatomy and Physiology by Professor Owen. 
In young birds the first feathers are preceded in their 
passage through the skin by filaments of down ; but after 
the first plumage, at the regular period of moulting, each 
old feather is the pioneer of that which is to follow. 
The natural moult proceeds by degrees, and the large 
quill-feathers of the wings and tail are generally shed by 
pairs. 
“ Although the feathers of birds appear to be an entire 
and uniform covering, they do not arise equally from every 
