52 Proceedings of the Royal Physical Society. 
Canada goose. The following are the particulars in which it 
differs : — 
In colour. — In the Canada goose the white cravat does not 
extend downwards along the under side of the neck, but is 
quite abruptly defined, and cut off ; in B. leucolcema it does, so 
as to give the appearance not only of a white cravat under 
its chin, but also a white frill or shirt appearing in front down 
its black waistcoat. In the Canada goose the white cravat is 
flecked more or less with blackish specks ; in leucolcema it is 
wholly white. In the Canada goose, the black head in front of, 
and above the white cravat, is wholly black ; in leucolcema it is 
flecked with an occasional white speck, and most so where it 
joins the upper mandible both in front and on each side. In the 
Canada goose the space betw^een the rami of the lower man- 
dible is black or blackish ; in leucolceina it is pure white. The 
white on the lower eyelid is comparatively broad and distinct 
in leucolcema; in the Canada goose it is a mere line like a 
thread. 
The general tone of the plumage of the body, both above 
and below, is considerably paler m leucolcema than in the 
Canada goose — the black primaries having become brown, the 
brown back having become somewhat fawn-coloured, and the 
fawn-coloured under side having become dirty white, with a 
pale bluish or lavender-coloured broad band stretching across 
the belly between the two thighs. 
The black on the neck extends rather a shorter distance 
down in leucolcema than in the Canada goose. 
The legs are yellowish-brown, and the interdigital spaces 
bright yellow in leucolcema^ instead of being black as in the 
Canada goose. I believe that in some species of geese the 
colour of the leg changes according to the age ; but this would 
not appear to be the case in the Canada goose, because Cap- 
tain Ord informs me that the colour is constantly black, 
both in old birds and young broods, which he has reared since 
1852. 
There are also some differences in the relative proportions, 
which I shall tabulate for the sake of brevity and easier refe- 
rence, and shall include in the comparison the proportions of 
the following species supposed to be B, Hutchinsii. The mea- 
