58 
HISTORY OF 
these birds is much lighter than that of Larus ; they generally 
feed on the edge of the water, sometimes wading, for which 
their partially naked thighs peculiarly adapt them. 
Of the four sub genera into which we propose to divide the 
Gulls, perhaps that of Rissa, Leach, containing the Kittiwake, 
comes nearest to Lestris. We shall therefore place it first, 
and Xema, Leach, last, as coming nearest to the Terns, (Genus 
Sterna, Linn.) The subdivisions of the genus Larus, therefore, 
will stand thus : — 
Sid) gen. 1. Rissa, Leach. 
Wanting the hind toe; tarsi, moderate. 
2. Larus, Stephens. 
Hind toe, perfect ; tarsi, strong ; thighs, fea- 
thered, nearly to the joints; head, white in 
the summer and winter plumage ; tail, 
rounded. 
3. Chroicocephalus, Nobis. 
Hind toe, perfect ; tarsi, slender ; thighs, much 
denuded ; tail, rounded ; head, dark coloured 
in the summer plumage. 
4. Xema, Leach. 
Tail, forked. 
