RARER BRITISH BIRDS. 
89 
position, as in C. Bewickii ; and, before reaching the external 
aperture by which it entered the sternum, is suddenly elevated 
about two inches above the line of the superior surface of the 
keel. Mr. Yarrell’s paper on this bird was read before the 
Linnaean Society, March 20, 1832, and published in the “ Tran- 
sactions” of that Society ; to which we must refer our readers 
for further particulars. 
The Swan commonly seen on our pools, in a half wild state, 
is an introduced species, and does not properly belong to our 
Fauna. Its trachea does not penetrate the sternum. 
During the winter 1829-30, many specimens of Cygnus 
Bewickii were obtained in the British Isles. Mr. Yarrell pur- 
chased five examples in the London market, and we were 
fortunate enough to obtain four from the Cambridgeshire fens. 
We have also observed a specimen in the Birmingham Museum. 
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