252 LARINJE CETOSPARACTES. RHOBOSTETHIA. 
nearly straight scutella, laterally and behind with very 
small prominent scales ; hind toe very small, little elevated, 
with a stout decurved claw ; fore toes short, longer than the 
tarsus ; membranes emarginate, strongly crenulate, the outer 
with a sinus ; claws moderate, strong, well-curved, rather 
acute. Plumage very full, close, soft ; wings very long, 
rather broad, pointed ; the outer two primaries with a sinus 
on the inner web near the obtuse tip ; tail of moderate 
length, a little rounded, of twelve broad feathers. 
309. Cetosparactes eburneus. Ivory Whale-bird. 
Bill stout, an inch and a third in length, half an inch high 
at the knob ; tarsus rough behind, an inch and a half long. 
Adult with the bill greenish-grey, yellow tinged with red be- 
yond the nostrils ; feet black ; plumage white, slightly tinged 
with yellow. Young with the bill dusky, pale yellow at the 
end ; feet black ; plumage white, variegated with brownish- 
black, each feather having a large round spot toward the end ; 
forehead and loral spaces bluish-grey. 
Male, 20, 42, 14^, l x %, 1 T ^, 1 1 3 ^? t 5 2 *» 
This bird inhabits the Arctic regions of both continents, 
and in particular the coasts of Spitzbergen and Greenland, 
on the cliffs of which it breeds. It is said to be less shy than 
gulls generally are, being nearly as fearless as the Fulmar, 
with which it associates while feeding on dead whales ; to 
have a strong and harsh voice ; and, unless when engagedin 
breeding, to be usually met with on the open sea. Yeryfew 
instances of its visiting Britain have been recorded. The first 
of these came under the observation of Dr Lawrence Edmond- 
ston, who, in the fourth volume of the Memoirs of the Wer- 
nerian Society, has described a young individual shot in Balta 
Sound, Shetland, on the 13th December 1822. It has also 
been shot in the Frith of Clyde and on the west coast of Ire- 
land. 
Ivory Gull. White Gull. Senator. 
Larus eburneus, Gmel. Syst. Nat. i. 596. — Larus eburneus, 
Lath. Ind. Ornith, ii. 816. — Larus ebmneus, Teram. Man. 
d’Ornith. ii. 769, iii. 474. Cetosparactes eburneus, Ivory 
Whale-bird, MacGillivray, Brit. Birds, v. 
GENUS CLIII. RHODOSTETHIA. ROSY-GULL. 
A small gull, singular from the cuneated form of its tail, 
and remarkable in other respects, has, not improperly, I 
