Mr. R. F. Tomes on White’s Thrush. 
387 
even more so than in that species. The lateral notches enter into 
the bone for half its length, and are proportionally broad; while 
the side processes are so short that their outer angle reaches 
scarcely further in a forward direction than two-thirds of the 
entire length of the sternum, taken along the line of the keel. 
Wishing, if possible, to ascertain more exactly the importance 
of this character, and knowing that the adult plumage of Oreo- 
cincla represents the immature plumage of some of the more 
typical Thrushes, I obtained for examination some of the latter 
when in that stage of plumage which most nearly resembles that 
of the Oreocincla . The results were satisfactory. I select as 
an example the Missel-thrush. In a mature bird the hinder 
margin of the sternum is transverse and but slightly rounded,— 
the notches on either side being of moderate size, and almost 
closed posteriorly. In a young bird, full-grown but retaining the 
spotted nesting-plumage, the hinder margin of the sternum is 
more rounded, and its lateral incisions are deep and open—in 
a word, very much like that part of the sternum of the Oreo¬ 
cincla aurea. The same differences in the sternum at different 
ages obtain also in the Ring-ousel, probably also in many other 
species. 
Through the great kindness of Mr. Alfred Newton I am 
enabled to add a few notes on the sternum of some other 
Turdidce :— 
1. Turdus migratorius .—Form typical, sternum indicating a 
state of development similar to those of the Fieldfare and Ring- 
ousel. 
2. T. fuscatus, Vieill. West Indies.—Two sterna of this 
species, sent by Mr. Newton, differ somewhat in the size and 
openness of the notch in the hinder part, but in both they are 
of moderate size. In one they are very like those in the ster¬ 
num of the adult Missel-thrush; but in the other they are so 
much closed posteriorly as to present the appearance of two oval 
foramina. In general outline, too, the sternum of this species 
and the Missel-thrush bear considerable resemblance to each 
other. 
3. Monticola cyanea .—The first thing noticeable in the sternum 
of this species is its small size compared with that of the Redwing 
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